In silico Methods for Modeling of Genomic Regions for Immunological and Metabolic Gene Modulating to Stress Response in Chicken: Where We Are?

Iranian Journal of Applied Animal Science

مقاله 1، دوره 12، شماره 3، آذر 2022، صفحه 415-432   

نوع مقاله: Review Article

نویسندگان

M.S. Ekhtiyari¹؛ A.S. Sadr^{* 2}؛ M. Shirali³؛ A. Javanmard^{* 4}

¹Department of Biochemistry, Faculty of Veterinary Medicine, University of Tabriz, Tabriz, Iran

²Aquaculture Research Center-South of Iran, Iranian Fisheries Science Research Institute, Agricultural Research Education and Extension Organization (AREEO), Ahvaz, Iran

³Agri-Food and Biosciences Institute, Hillsborough, BT26 6DR, United Kingdom

⁴Department of Animal Science, Faculty of Agriculture, University of Tabriz, Tabriz, Iran

چکیده

Traditionally, commercial broilers are not well adapted and currently subjected to a variety of environmental challenges. In recent years, researchers have shown an increased interest in stress as one of the greatest environmental challenges to the profitability of sustainable intensive poultry production. In this scenario, understanding the complexity of the molecular basis and genomics of the stress response is critical to successful breeding programs for climate-adapted chickens. Recently, numerous popular studies have attempted to identify candidate genes that control stress responses in chickens. However, a number of questions regarding the choice of stress response remain unanswered or inadequately answered regarding the number of lead candidate genes that control components of the non-infectious and infectious stress response. With this motivation, 89 journal articles were collected for the primary investigation and those with low validity were excluded from further analysis. In short, we used three types of information sources, namely: text-based systematic review, in silico modeling, and both network and pathway approaches, to introduce more effective and bio-indicators of gene-controlling stress responses in chickens through older literature. Gene ontology (GO) and pathway networking of candidate gene associated with stress was loaded into Cytoscape for analysis. The result provides additional evidence and highlights, including nearly 9 candidate genes. According to published studies, CRYAB, HSP90AA1, IL6, HSPA2, HSF2, HSPB1, HSF3, PLK1, BAG3 are mostly associated with non-infectious and infectious stressors and may deserve further attention. String database analysis illustrated role of highlighted gene in multiple cellular task and functionally such as ATPase activity, cellular processes, including protection of the proteome from stress, folding and transport of newly synthesized polypeptides, activation of proteolysis of misfold proteins and the formation and dissociation of protein complexes. Obtained information from Animal QTL database indicated important role of chromosomes numbers 2, 3, 4, 5, 12, 14 and 24 associated with stress resistance and susceptibility. On this basis, this report attempts to find out which genomic regions control homeostasis and promote cell survival, molecular transport and cell signaling.

کلیدواژه‌ها

controlling homeostasis؛ gene networking؛ genomics؛ stress response

اصل مقاله

INTRODUCTION

Traditionally, commercial broilers are not well adapted and currently subjected to a variety of environmental challenges. One of the greatest environmental challenges to the profitability of sustainable intensive poultry production is stress. Stress can be defined as a state of threatened homeostasis (Virden and Kidd, 2009). Research into the etiology of stress and environmental problems in poultry farming has a long history. Stress can have negative effects on the health and performance of chickens (Bogusławska-Tryk et al. 2012) as well as on human nutrition (Takeda et al. 2004). Stress is a huge umbrella term that can encompass a complex reaction of chicken cells in the chemical-immunological, metabolic and genetic response to threatening conditions (Liu et al. 2019). A considerable amount of literature has recently appeared on environmental factors influencing physiological homeostasis, genomics of adaptation, and immunological and metabolic factors influencing stress response in chicken breeds (Soleimani et al. 2011; Sohn et al. 2015). There have been numerous surveys to study chickens' response to threatening conditions that highlighted environmental components of non-infectious and infectious stressors such as: physical factors (heat, cold, relative humidity, and changes in oxygen tension with altitude (Bessei, 2006), housing conditions, group sizes, nutritional factors (nutritional deficiency, feed restrictions, change in feed composition) (Waldenstedt, 2006), physiological factors (body pH, body temperature), glucose level and oxygen tension, muscle building (changes in the muscle composition of protein, fat, potassium, magnesium, calcium and sodium) as well as metabolic and infectious microbial and viral diseases (Nidamanuri et al. 2017). There is a considerable body of literature on type responses and complex and multi-layered mechanisms of the chicken body's response to stressors, which can be briefly divided into: behavior, changes in the autonomic nervous system, abnormal behavior, physiological and endocrine systems, metabolic and assisted immunological responses can identify who is susceptible and resistant to stressful conditions (Khan et al. 2021). Upon heat stress, heat loss is increased through radiation, convection, conduction and evaporation. While it is generally accepted that poultry farming can be achieved between 10 and 27 ˚C, maximum yield is achieved in the narrower temperature range: around 18-22 ˚C for broilers in Growing at 19-22 ˚C for layers (Figure 1). Birds raised under heat stress conditions showed signs of panting and flapping wings, body temperature, lower feed consumption, higher feed conversion rate, and lower body weight gain (Hafeez et al. 2021). The link between quantitative and molecular genetics has provided invaluable advantages in identifying the molecular basis of the stress response and the gene networking of genomic regions for gene modulating the stress response in chickens. Although the molecular basis and polygenic genetic architecture of the stress response have been extensively researched, candidate gene polymorphism, gene expression profiling, QTL mapping, epigenetic programming, post-transcriptional changes in signal genes, GWAS and RNA-Seq studies of the stress response are few studies that systematically examine the contribution of key genes to networking alone in stress response variation, and more systematic and theoretical analysis is required to understand the complexity of cellular signaling pathways and associated cell signaling (Perini et al. 2020).

 

The regular review of articles

Systematic reviews can be seen as useful tools for developing concepts and identifying knowledge gaps and prioritizing areas for future research on the genomics of stress in chickens. For this reason, the PRISMA protocol has been used as a framework for a systematic study of key candidate genes that affect stress in chickens (Piray and Foroutanifar, 2021). A total of 124 articles were collected and later checked for duplicates, 89 articles were included for further analysis. The articles contain 24 different factors on different chromosomes that are most closely related to stress. The raw material for this report was provided using search engines, Science Direct, PubMed, SCIRUS, Oxford Journals, Cambridge Journals, Springer Journals and the Wiley Library, the NCBI website and Google Scholar. Most of the keywords were chosen to find the target papers: stress in chickens, candidate gene, QTL mapping, gene expression, networking and genetic ontology, GWAS and RNA-Seq profile. The search was limited to chicken species and most articles were in English and Endnote software was used to remove duplicates and sort papers. A brief list of the key genes for stress in chickens is then provided to readers. Criteria for networking were assessed: between centrality, attributes, co-expression, predicted genetic interactions, signaling pathways, physical interactions, common protein domains and co-locations. A brief list of the key genes for stress in chickens is then provided to readers. Criteria for networking were assessed: between centrality, attributes, co-expression, predicted genetic interactions, signaling pathways, physical interactions, common protein domains and co-locations. Finally, to better understand the relationship between the genes obtained in this study, a network was created using the STRING tool (http://string-db.org) and 24 candidate genes as input.

 

The ACTC1 gene-gene ID: 423298

Actin Alpha Cardiac Muscle 1 (ACTC1) is a highly conserved protein that plays an important role in premature muscle and fetus growth (McNally and Dellefave, 2009), and the decreased expression of ACTC1 is a potential biomarker that plays a key role in the innate heart. The disease and the atrial septum play a defect. This candidate gene was found in chromosome 5 in the chicken genome and has 7 exons and 377 amino acids (Jiang et al. 2010; Matsson et al. 2008).

 

Figure 1 Optimum zone for performance and health in chicken physiology

 

Cheung et al. 2017 showed that the cardiac form of actin ACTC1 is continuously regulated in the skeletal muscle of males and mice. This is most likely regulated by an intermediate androgen receptor pathway mediated as ACTC1 by dihydrotestosterone (DHT) in the gastrocnemius muscles of rodents (Cheung et al. 2017). ACTC1 is also involved in small molecule biochemistry, molecular transport and molecular transport, lipid metabolism, and small molecule biochemistry (Nam et al. 2012; Wu et al. 2013). Many research studies (Nam et al. 2012) have shown that the ACTC1 gene is involved in muscle growth and meat quality. ACTC1 is upregulated under heat stress and during heat stress its convolution changed from 1.51 to 15.14 (Gaudet et al. 2011).

 

The ADRA2C gene-gene ID: 428799

The A-adrenergic receptor gene 2C (ADRA2C) is located in chromosome 4 chicken genome and consists of a single 1229 bp exon, starting at chromosome 4: 84590769, transcribed from 3 to 5, located at 10769 bp and with 446 amino acid residues. This gene is an effective gene to show stress-induced domestication behavior in animals and is fully associated with flight combat and reaction as well as stress-related behavior. This ADRA2C protein is absent in mammals and crocodiles. It is common in the central nervous system and kidneys and also plays a key role in regulating the release of adrenaline from the adrenal medulla. ADRA2C functions as an autoreceptor in presynaptic sympathetic nerve cells and is involved in the regulation of noradrenaline secretion with a negative feedback loop (Brede et al. 2003). ADRA2C is expressed in the CNS, where it cooperates with ADRA2A in a negative feedback loop prior to the synapse in releasing norepinephrine. ADRA2A controls potential excitation frequencies with high power and ADRA2C does the same for excitation frequencies with low potential. Low fears and high stress thresholds should be essential traits for animals during early domestication. ADRA2C is a major regulator of epinephrine secretion from the adrenal gland and can therefore be a good target for domestication remodeling (Elfwing et al. 2014).

 

The ApoB gene- gene ID: 396535

The apolipoprotein B (ApoB) gene plays a regulatory role in cholesterol homeostasis, cholesterol metabolism, cholesterol transport, lipid transport, lipoprotein transport pathways and was found in chromosome 3 chicken genome and exon number is 29 and also consists of 4631 amino acids. Chronic heat stress can increase fat synthesis in broilers, and excess triglycerides (TG) formed in the liver must be transported into the extrahepatic tissue through very low density lipoprotein tissue (VLDL). Otherwise, it will accumulate in the liver, which can even lead to liver steatosis. ApoB is an essential part of VLDL from the liver. One study reported that ApoB gene expression is stable without estrogen stimulation, and ApoB secretion is post-translational because it controls VLDL. By measuring the ApoB level using an immunoassay, it was found that exposure to chronic heat at the level of the ApoB level does not affect the liver (Lu et al. 2019). Therefore, broilers exposed to chronic heat stress may be the main cause of fat accumulation in liver tissue, lack of stimulation of ApoB against heat stress (Ginsberg et al. 2005). Computer analysis showed that chickens 4/631 amino acids encoded by ApoB are predicted with 20 amino acids as a signal peptide with a molecular mass of 524 kDa and an isoelectric point of 8.49. A sequence comparison showed that the sequence of the amino acids from the ApoB gene from chickens is 49% identical to that of humans (Gen-Bank No. NM 000384) and 38% identical to the muscle of Mus (GenBank No.XM 137955). Analysis by SMART showed that N-terminal regions (45-597) of ApoB chickens included the N-terminal region of lipoprotein (LPD-N). The N-terminal domain of ApoB is structurally homologous to that of lipovitellin and the microsomal triglyceride transfer protein (Segrest et al. 1999). High expression levels were observed in the kidneys, liver and intestines, while low expression levels were observed in the heart, spleen, gizzard, belly fat, brain and leg muscles. ApoB has two isoforms in the bone marrow called Apo100 and Apo48, which are expressed in the liver and intestine, but so far only the Apo100 isoform has been described in chickens (Zhang et al. 2007).

 

The ARRDC3 gene-gene ID: 427107

The arrestin domain, which contains the 3 (ARRDC3) gene, encodes a member of the arrestin family of proteins that regulate G-protein mediated signaling, and this gene is also a potent regulator of PPAR signal and the endosomal functions. In the chicken genome, this candidate gene was in chromosome? The Z and exon number for this gene is 8 and consists of 414 amino acids. Studies were performed with the arrestin domain-containing 3 (ARRDC3) gene located between 947 kb and 888 kb and below the 2nd and 3rd markers. This gene codes for the human protein arrestin domain-containing protein (www.uniprot.org). Writings show that the expression of the ARRDC3 gene in the male amputum (intra-abdominal fat) increases with increasing body mass index and body volume. In this regard, the adipose tissue detached from the rat ARRDC3-NULL system shows that adrenergic visual acuity has increased dramatically. In fact, stimulating adrenaline by increasing CAMP signaling will increase fat loss. ARRDC3 causes obesity resistance, which is usually associated with aging. However, the physiological poison of obesity resistance in the rat ARRDC3-NULL system has been adjusted by increasing the signal through the beta-3 adrenergic receptor (B3-AR) required for non-vibration and heat production. There is evidence that this effect is due to increased heat production in both white and brown adipose tissue at the molecular level through the interaction between ARRDC3 and beta-adrenergic receptors, which limits the body's response to catecholamines. Therefore, with high ARRDC3 values, the energy consumption is low, which reduces the heat production in the body. This evidence suggests that these signals, which regulate ARRDC3 expression, make the bird resistant to rising temperatures (Patwari et al. 2011). Based on the above, and since this gene has similar functions in humans, mice and chickens, it can be said that this gene can increase the birds' resistance to temperature rise by reducing body heat production and raising the temperature tolerance threshold in birds (www.uniprot.org).

 

The BAG3 gene-gene ID: 423931

BCL2-associated athanogen 3 (BAG3) maybe candidate genes for thermotolerance in roosters and may be dramatically altered in heat-stressed chickens. This gene has a negative regulatory effect on apoptosis and can be used to reduce apoptosis in chickens exposed to heat stress. This candidate gene was in chromosome 6 chicken genome and consisted of 4 exons and 560 amino acids. BAG3 is the only member of the BAG family that can be caused by heat-stressed. BAG3 has been reported to be associated with apoptosis, development, protein breakdown, and skeletal organization. In heat-stressed chickens, the antibody-associated genes BAG3 and SERPINB2 are re-regulated. Adapted BAG3 can be linked to the breakdown of antibodies and proteins to alleviate the damage caused by acute heat stress in chicken testicles. In the animal model, a deficiency or a mutation of BAG3 leads to a myopathic phenotype (Wang et al. 2013). The BAG3 gene responds to stress from heat shock factor 1. Although BAG3 is widespread in many tissues, it is more pronounced in the skeletal and heart muscles, where it is located on the Z-disk of the sarcoma. The BAG3 protein modulates the ATP turnover and the folding activity of the HSP70 protein (induced) and the HSC70 protein (constitutive) as a co-chaperone. It also interacts with a separate family of chaperones, small thermal shock proteins (HSPB genes), and combines the power of the HSP70 and HSPB families. The BAG3-HSP70-HSPB complex regulates autophagy pathways in human cells and is also effective in the breakdown and regulation of ubiquitinated proteins by proteasomes (Judge et al. 2017).

 

The BCL2 gene-gene ID: 396282

B-cell lymphoma 2 (Bcl-2) proteins exist at the height of apoptosis after the onset of cellular stress, and this candidate gene modulates ROS-mediated programmed cell death. This gene was taken up in chromosome 2 chicken genomes and the exon number of this gene is 2 and consists of 233 amino acids. This genetic ontology and connection is B-cell homeostasis, commitment to the B-cell line, B-cell proliferation, B-cell receptor signaling pathway, CD8 positive, commitment to the alpha-beta T-cell line, T-cell differentiation into thymus, T-cell homeostasis, actin filament organization, axon regeneration, axonogenesis, behavioral anxiety reaction, cell aging, cell-cell adhesion, cellular response to glucose deficiency, cellular response to hypoxia, cellular response to organic substances and defense reaction to viruses. Mitochondria play an important role in apoptosis and autophagy and are the main site of oxidative stress. Mitochondrial dynamics (fusion and splitting) play a key role in maintaining their shape, size, number, and function. Moll reported that p53 could interact with the X protein associated with Bcl-2 (Bax) and Bcl-2 at the mitochondrial level and has the ability to stop cell proliferation and stimulate apoptosis (Liu et al. 2019). Studies have shown that after exposure to the endoplasmic reticulum (ER), apoptosis can co-operate with autophagy (a mechanism that kills the second cell) (Mihara et al. 2003). Qin et al. (1997) report that during treatment for T lymphocyte leukemia with As2O3, they activated apoptosis and autophagy by upregulating Beclin-1, resulting in cell death and tumor remission. Beclin-1, a BH3 protein, can bind to Bcl-2 to form the Beclin-1-Bcl-2 complex, which inhibits Beclin-1-mediated autophagy. However, the high expression of the Bcl-2-associated X protein (Bax) can separate the Beclin-1-Bcl-2 complex, resulting in autophagy and apoptotically sensitive cells. The results of the analysis, which according to previous studies show that the interaction between Bcl-2 and Beclin-1 could be between autophagy and intermediate apoptosis (Huang et al. 2013; Liu et al. 2019). Bcl-2 protects cells from apoptosis by various stress factors and is mainly expressed in the outer membrane of the mitochondria. The Bcl-2 family can be divided into two groups: antiapoptotic (similar to the Bcl-2 proteins such as Bcl-2 and Bcl-X L) and apoptotic stimulants (such as Bax-like and BH3-only protein). Proteins that promote apoptosis release cytochrome C from the mitochondria into the cytoplasm. However, Bcl-2-like proteins can prevent Bax-induced cell death by preventing the release of the cytochrome C content, which causes the release of cytochrome C and the onset of apoptosis in the spleen (Figure 2) (Huang et al. 2013).

 

The CALB1 gene-gene ID: 396519

Calbindin 1 (CALB1) is a 27 kDa protein and belongs to the superfamily of calcium-binding proteins. It was found that the CALB1 transcript level in the heat stress group of the hens was increased by 34.2-fold compared to the controls. This candidate gene was in chromosome 2 and consists of 11 exons and genetic ontology and pathway analysis show that this gene has calcium ion transport, cellular calcium ion homeostasis, cellular response to organic substances, locomotor behavior, long-term memory, metanephric manifold development, metanephric connection, tubular development, anephric distal tubule development and sensory pain perception. This gene consisted of 262 amino acids. Calcium transfer in uterine fluids includes TRPV6 or other calcium channels to penetrate the cells of the uterine gland, calbindin D 28k (CALB1: function= Ca+2 transporter (intracellular)) for intracellular transport, and calcium excretion occurs through calcium converters Na⁺/Ca^{+ 2} or Ca^{+ 2}/H⁺. As an intracellular transporter, calbindin 1 (CALB1) is able to transport Ca⁺² through the cell and acts as a Ca⁺² sensor and buffer for cytoplasmic Ca ⁺² buffers, causing the intracellular Ca ⁺² concentration to be toxic level is prevented. CALB1 is commonly expressed in various tissues such as the uterus, retina, brain, kidneys, intestines, bones, and pancreas. This protein is an important factor in egg formation and significantly increases uterine expression during egg shell calcification. However, CALB1 maintains low intracellular calcium ions in various cells to prevent cell death and apoptosis (Adji et al. 2019). An increase in CALB1 in prostate cancer cells has been observed during heat stress (Li et al. 2011a), which may be related to its compensatory and protective effects against abnormal mineralization and apoptosis. A positive association between egg quality and CALB1 was confirmed in the uterine cavity. Studies have shown that the release of many hormones such as estrogen, glucocorticoids, and catecholamines is associated with changes in heat stress. These hormones can differentiate the expression of the CALB1 gene in tissues (Ebeid et al. 2012).

 

The PLK1 gene-gene ID: 416575

Serine / threonine protein kinase PLK1, also known as polo-like kinase 1 (PLK-1) or serine / threonine protein kinase 13 (STPK13), is an enzyme that temporarily interacts with mitotic structures such as the spindle apparatus, kinetochores, and centrosomes. This candidate gene was located in the chromosome 14 chicken genome and has a number of 10 exons and also consisted of 595 amino acids. PLK1 pro-tein activity is required for cell cycle progression regulate several aspects of cell division including centrosome maturation (Javadi Esfehani, 2014). PLK proteins are important regulators of the cell cycle. This gene plays an important and key role in activating and regulating the activity of these proteins by stimulating and interacting with enzymes of the PLK family, particularly PLK1 and PLK4 (Casenghi et al. 2003). PLK1 substrates contain several proteins involved in mitosis, including APC, CDC25C, and CLYNB, which regulate the rate of dephosphorylation of tyrosine by CDKs (Asteriti et al. 2010). Studies have shown that through the phosphorylation of HSF-1 in serine 419 by PLK1 and the interaction between HSF-1 and PLK1 under thermal stress, an interaction between PLK1 and HSF-1 proteins exists in the body and this is strengthened and effective at the regulation of the thermal load.

 

Figure 2 Beclin 1 complex: multiple, mechanisms regulating autophagy/apoptosis toggle switch (inhibition: ┤, activation: →)

 

The results show that mutations in serine 419 to alanine and the inhibition of thermal stress are due to HSF-1 nuclear transfer and that HSF-1 phosphorylation by PLK1 is an essential step for HSF-1 activity under thermal stress (Kim et al. 2005). As a result, PLK1 plays an important role in the activation and regulation of HSF-1 protein activity under thermal stress. In normal cells, HSF-1 is largely concentrated in the cytoplasm as an inactive monomer. Hemothyroidism (essential for HSF-1 activity) is altered and transferred into the nucleus to bind to DNA. Thereafter, HSF-1 binds to the elements or elements of thermal shock (HSES), which are repetitive reverse structures of 5 nucleotide motifs in the promoter region of HSP genes, thereby increasing the expression of HSP genes, including HSP70 and HSP90. In various organisms, the regulation of HSP protein expression in response to stress is primarily dependent on the HSF-1 transcript (Kim et al. 2005). In fact, the activity of HSF-1 proteins increases the cellular level of heat shock proteins (HSPs), which are used as molecular protection to denature and reduce these proteins as well as protect the cell (Fink, 1999).

 

The CRH gene-gene ID: 404297

Corticotropin-releasing hormone (CRH) affects resistance or susceptibility to heat stress, and a peptide hormone involved in the stress response has the main function of stimulating pituitary synthesis of ACTH as part of the HPA axis. This gene was found in chromosome 2 Gallus gallus and has two exons and 167 amino acids. In fish, the corticotropin-releasing hormone (CRH) is the dominant hypothalamic hormone that controls the stress axis. CRH is derived from a 160 amino acid of the preprohormone, which is broken down into a mature bioactive peptide of 41 amino acids. With recent efforts at the full genome sequence, two family members such as CRH have been identified to date, urocortin-II and -III. These peptides signal via seven-helix G protein-coupled receptors. UII appears to use its own receptor, but the two receptors for CRH and UcnI (CRH-R1 and CRH-R2) overlap the ligand properties. CRH-R1 has the same affinity for CRH and UcnI/UI in catfish and mammals, while CRH-R2 has a higher affinity for Ucn than CRH. CRH, CRH-R1, and CRH-BP are some of the key molecules that regulate the response to vertebral stress. For each of the three proteins described there are two very similar genes (0.95% amino acid identity) (Huising et al. 2004). In the pituitary gland of chickens, CRH-R2 was clearly expressed by thyrotropes, indicating that it is involved in the secretion of CRH stimulant for TSH release. ACTH after binding to CRH-R1, while CRH-induced TSH secretion is mediated by CRH-R2 on thyrotropies. This mechanism allows the pituitary action of CRH to be fine-tuned. Depending on requirements, CRH can preferentially release ACTH, TSH or both via various regulated receptors (Figure 3) (De Groef et al. 2003).

 

Figure 3 CRH pathway (the stress response begins in the brain; the function of the hypothalamus is very similar to that of the command center, which triggers a cascade that eventually leads to the secretion of cortisol, which in turn stimulates the immune system)

 

The CRYAB gene-gene ID: 396089

Crystallin Alpha B (CRYAB) belongs to the family of small heat shock proteins (sHSP) and lowers the cellular CRYAB level through heat stress. CRYAB is a member of the sHSP family (HSPB1HSPB10) that acts as a chaperone and occurs in several organs and could also play an important role in heart cells. This candidate gene was in chromosome 24 the genome of chickens, and their exon numbers are 3 and consist of 174 amino acids. Gene ontology and signal path analysis showed their regulatory role in the following signal pathways: apoptotic process that is involved in morphogenesis, cellular reaction to gamma radiation, lens development in the camera eye, muscle organ development, negative regulation of intracellular transport, negative regulation of the protein complex structure, negative regulation of transcription, DNA Template, protein stabilization, response to hydrogen peroxide, response to hypoxia and tubulin complex formation. The small heat shock protein B-crystallin (CryAB, HSPB5, 20 kg Dalton) belongs to the family of sHSP and reacts in most organisms to different types of stress (e.g. cell protection (Li et al. 2011b). CryAB has also been shown to have anti-apoptotic properties because in conditions such as stroke it can prevent cell death by preserving the skeletal structure of cells. Mechanically, CryAB is localized in the I-band and M-line region in myofibrils and plays a stabilizing role in vitro for myofibrils in cardiomyocytes (Wieske et al. 2001). It is now believed that the pleiotropic functions of CryABs are the result of their multiple interactions with a variety of different proteins. Previous research has shown the expression and localization of CryAB and has shown that it plays a protective role against heat stress in mice in vivo and in vitro. However, the performance of CryABs is poor compared to other members of the sHSP family. The cytoskeleton plays a key role in maintaining the body shape of heart cells, protecting against stress from the endoplasmic reticulum (ER), and maintaining mitochondrial function in vivo and in vitro (Figure 4) (Tang et al. 2016; Zhang et al. 2019).

 

The FABP1 gene-gene ID: 374015

Fatty acid binding protein (FABP1) is highly transcribed in liver cells and this protein affects lipid metabolism by regulating PPARalpha and L-BABP in chicken hepatocytes. This gene was located in the chromosome 4 chicken genome and consisted of 4 exons and 127 amino acids. This suggests that free radical production was linked to L-FABP production during cold stress. Cold stress provokes the body to produce additional free radicals, which are suppressed by unsaturated fatty acids from the biomembrane membranes. Hence, it destroys the integrity of the cell membrane and causes severe damage to the cell membrane. It has been reported that L-FABP has a high affinity for unsaturated fatty acids and lipid peroxides, which can support cell membranes by preventing the oxidation of unsaturated fatty acids and damage to cell membranes by lipid peroxides. In addition, by simply releasing it, L-FABP can transport fatty acids into the mitochondria or endoplasmic reticulum so that homeostasis regulates the liver's lipid metabolism. Lipid synthesis for energy storage can be the first response to prolonged cold stress. In addition, the binding of L-FABP to fatty acids can generate energy through oxidation. It's esterified to produce phospholipids to resist cell membrane damage or to produce triglycerides to complete fat loss (Chen et al. 2015).

 

The HSF1 gene-gene ID: 420362

Heat shock factor 1 (HSF1) is a stress-inducible and DNA-binding transcription factor that plays a central role in the transcriptional activation of the heat shock response. HSF1 is the main regulator of heat shock genes. HSF1 is activated at lower temperatures than HSF3, while HSF3 binds and is activated at higher and longer temperatures. The heat shock factors (HSF) and heat shock proteins (HSP) are the main mechanisms of cell protection against environmental heat stress. This candidate gene was found in the chr. 2 chicken genome and has 11 exons and 491 amino acids (aa). The genetic ontology and pathway analysis of this candidate gene showed its role in the following pathways: DNA binding, DNA binding, DNA binding transcription factor activity, RNA polymerase II promoter sequence-specific DNA binding, chromatin-DNA binding, core-promoter sequence-specific DNA binding, heat shock protein binding, promoter-specific chromatin binding, protein homodimerizing activity, protein self-association and sequence-specific DNA binding. The HSF1 trimmer and HSF3 dimmer can be connected to the HSPs heat shock element (HSE) to make HSPs. HSF1 was involved in the further synthesis of HSPs, while HSF3 was only required in avian species for HSR (the heat shock reaction). In addition, some research suggests that HSF3 plays an important role in the induction of HSPs 70 in chickens compared to HSF1. The results showed that the expression of the HSF1 and HSF3 genes can be adjusted by heat stress in the chicken heart. These results suggest that HSF1 and HSF3 may play an important role in the re-regulation of HSP70 (Fujimoto et al. 2010). Both HSF1 and HSF3 are available as a monomer form under normal conditions, and when the cell is under stress, the HSF1 trimmer and HSF3 dimmer can be combined with the HSE to mediate expression of thermal shock proteins. Therefore, the formation of HSF polymers was a prerequisite for the expression of thermal shock proteins, the results on the native side showed that the expression of total HSF1 and HSF3 was regulated under thermal stress, HSF1 trimmer formation and HSF3 dimmer also decreased under heat stress (Figure 5) (Xu et al. 2019a).

 

The HSF2 gene gene ID: 421724

Heat shock transcription factor 2 (HSF2) modulates the expression of heat shock genes by interacting directly with HSF1 or heat shock factor 4 (HSF4). This gene was found in chromosome 13 chicken genome and has 13 exons and 563 amino acids. In vertebrates, four members of the HSF family (HSF1, HSF2, HSF3 and HSF4) are bound to the thermal shock element (HSE), which is the inverse repeat of the consensus nGAAn sequence. HSF1 and HSF3 retain the DNA binding activity, both are transferred into the cell nucleus during thermal shock, while HSF2 does this only to a small extent. In addition, HSF1 mammals or HSF3 birds, but not HSF2, are necessary and sufficient to express HSP. Consequently, HSF1 significantly suppresses mouse models of protein misbinding diseases such as Huntington's disease and prion disease (Steele et al. 2008), e.g. single HSF in Caenorhabditis elegans. Since HSF2 is expressed abundantly and ubiquitously so that it can spread to vertebrate cells to express HSP, its growth patterns have been extensively analyzed. HSF2 has been shown to be important for brain development and reproduction (Chang et al. 2006). HSF2 is a short-term protein that is heavily regulated by the ubiquitin-proteasome pathway. Blocking the protease activates HSF2 and HSF1. HSF1, but not HSF2, is necessary for the upregulation of HSP expression during proteinase inhibition. Therefore, HSF2 is unlikely to be an important factor in the regulator of HSP expression. Instead, HSF2 is partially involved in the inductive expression of HSPs by interacting directly with HSF1 or by tagging the HSP gene during mitosis. HSF2 is turned on during heat shock, and its deficiency increases the sensitivity of vertebrate cells to heat shock. Heat shock leads to cell death through apoptosis and necrosis. However, the path of cell death and the primarily imperfect factors can vary depending on the temperature and duration of the heat shock. Indeed, HSF2 deficiency in mouse embryonic fibroblast (MEF) cells, unlike HSF1, has little effect on survival rates when exposed to extreme temperatures or heat. This significantly reduces the survival rate in the event of heat shock at high temperatures. Similarly, stress-related cell death phenotypes have been shown in HSF2-deficient mice. A unique need for HSF2 for cell survival, particularly under stable heat shock conditions, that is evolutionarily sustained in mammalian and poultry species. 

 

Figure 4 Schematic diagram of CRYAB protein involved in the regulation of apoptosis (inhibition: ┤, activation: →)

 

Figure 5 HSP25 overexpression in Dox-treated failing hearts of mice

 

HSF2 deficiency increases the accumulation of cellular proteins during sustained mild heat shock, suggesting that HSF2 reduces protein misfolding or destroys misfolded proteins. HSF2 regulates both folding and degradation pathways via B-crystallin expression. HSF2 deficiency, required for the expression of non-HSP proteins, increases the expression of HSPs by accelerating the activation of HSF1 rats or HSF3 chickens in mild hours (Åkerfelt et al. 2007).

 

The HSF3 gene-gene ID: 422169

The heat shock transcription factor 3 (HSF3) is stronger than HSF1 for the thermally induced expression of HSP genes. This candidate gene was in chromosome 4 and has 14 exon counts and 551 AA protein. The genetic ontology and signal path analysis of this gene showed that its key roles lie in the following signal pathways: DNA binding, DNA-binding transcription factor activity, RNA polymerase II promoter sequence-specific DNA binding, nuclear promoter sequence-specific DNA binding, Protein binding, protein homodimerizing activity, and sequence-specific DNA binding. HSPs are regulated by transcription factors called heat shock factors, 4 of which (HSF1, HSF2, HSF3 and HSF4) play key roles in stress biology (Zhang et al. 2014). Fujimoto and Nakai (2010) found that HSF1 is the most important HSP gene in mammals, while HSF3 is the most important HSP gene in poultry (Fujimoto et al. 2010). The binding of HSF1 to the HSP70 gene shock promoter is important in HSP70 transcription. HSPs are regulated by HSF1 during the stress response (Yasuhara et al. 2011). In chickens, at high temperatures, HSF1 affects the nucleus of the brain cells, causing them to express HSP. However, HSF3 is expressed in mild, moderate, and severely elevated temperatures in the brain and blood. The mRNA expression of HSF3 gene expression tissue is associated with different tissue requirements. 6 hours after the start of heat treatment, HSF3 mRNA expression in the heart increased further, while HSP70 mRNA expression decreased. HSP70 and HSF3 mRNA expression levels in Lingshan chicken tissue (LSC) are different from those of White Recessive Rock (WRR) chicken tissue under heat treatment, which reflects species characteristics (Zhang et al. 2014).

 

The HSPA2 (HSP70) gene-gene ID: 423504

Heat Shock Protein Family A (HSP70) Member 2 (HSPA2) is a 70 kDa protein that has been correlated with levels of mRNA expression and heat tolerance, which have been considered an effective marker for the selection of heat tolerant chickens. This gene was in chromosome 5 chicken genome and has 1 exon and has 634 aa. Genetic ontology and pathway analysis of this gene functionally indicated: ATP binding, ATPase activity, heat shock protein binding, misfolded protein binding, progesterone receptor binding, protein binding, protein binding involved in protein folding and unfolded protein binding. Some genes of the HSP family or their cochaperones are regulated in the testes of heat-stressed roosters, for example HSP70, HSP90AA1, HSPB8, HSPA5, DNAJB6, HSPA8, HSPB1, HSPA4, AHS2. FKBP4 and ST13 (Wang et al. 2013). The HSP70 family binds to newly synthesized polypeptides, preventing aggregation and promoting folding, while HSP90 interacts with customer proteins in the end-stage of folding and modifies their configuration. The duration and intensity of heat stress can also affect the expression pattern of HSPs. In broilers, acute heat stress leads to the expression of the HSP70 gene in the liver, lungs, heart, kidney, blood vessels and HSP 90 in the heart, liver and kidney (Mazzi et al. 2003). Increased expression of the mRNA expression of the HSP70 gene is associated with the simultaneous induction of the HSP70 protein, indicating that the induction of HSP70 is active at both the translational and transcriptional levels. High testosterone and corticosteroids appear to affect the protein HSP70 and HSP70 mRNA during heat stress. Among these HSPs, HSP70 is the best association with acquired thermometer, and this was confirmed by observations that the competitive inhibition of the expression of the HSP70 gene increased with increasing temperature. Mammalian cells cannot survive extreme heat stress when anti-HSP70 antibodies are used. In contrast, microinjection of HSP70 mRNA increases thermal cell resistance in mammalian oocytes (Wang and Edens, 1994; Ciocca et al. 2015). The expression of HSP70 varies between different genotypes or combinations of different haplotypes under normal conditions and heat stress. Heterozygous genotypes appear to be associated with a higher base level of homozygous genotypes than HSP70 in both liver and muscle tissue, but this does not apply to stress caused by stress in liver and brain tissue (Zhen et al. 2006). The HSP70 and HSP90 genes are the best-studied family of HSPs, and each has different functions. HSP70 binds to newly synthesized proteins, prevents their accumulation and helps with wrinkles.

 

The HSP90AA1 gene-gene ID: 423463

Heat shock protein HSP 90-alpha. The gene (HSP90aa1) is the stress-inducible isoform of the molecular chaperone HSP90 and this protein is a rich and ubiquitous molecular chaperone that plays an essential role in many cell biological processes. This gene was found in chromosome 5 chick genome and has 10 exon counts and consisted of 728 AA protein. Gene ontology and signal path analysis This gene showed contributions to the following signal pathways: HSP90 protein binding, TPR domain binding, chaperone binding, disordered domain-specific binding, estrogen receptor binding, heat shock protein binding, identical protein binding, nitric oxide synthase-regulatory activity, progesterone terminator binding and protein binding, protein C-terminal binding and protein binding. Some reports exposed broilers to heat stress and recorded large differences in HSP90 expression. The mechanism of HSP90 is such that it preserves the function of proteins through the formation of certain complexes including kinase proteins and steroid receptors (Csermely et al. 1993). In the presence of stressors, these proteins are more strongly expressed and synthesized than other proteins (Zhao et al. 2017). The anti-stress performance of HSP90 is achieved in two ways: 1- Support of the refolding structure 2- Suppression of non-specific protein accumulation. In addition, the function of HSP90 in hepatitis B has been shown to be related to reverse transcription. Hence, HSP90 control mechanisms in various tissues may be important as they are related to stressors. For example, there is a special relationship between HSF1 and this protein under stress conditions that can change, and HSF1 is separated from the mass and forms trimmers and invades the nucleus and controls the expression of HSP. More recent studies have shown that the expression of HSP90 is influenced by the interleukin-6 and Interferon-G signaling pathways, multifunctional cytokines. During physiological stress, the level of catecholamines secreted by the hypothalamic-pituitary-adrenal axis increases and increases the expression of HSP90. When stressed, calcium builds up in the muscles to which both alpha and beta 90 HSP are bound. It is noteworthy that in region B there is no diversity in the balance of the different species and the greatest difference is between fish and poultry compared to mammals. This region is very important for HSP90 mechanisms, mechanisms such as the regulation of the N-terminal chaperone functions and the tendency towards N-terminal binding to denatured proteins (Pepin et al. 2001; Åkerfelt et al. 2010).

 

The HSPB1 gene-gene ID: 396227

Heat shock protein beta-1 (also called heat shock protein 27) plays a role in stress resistance and actin organization. This gene was found in chromosome 19 in the chicken genome and has exon number 3 and consisted of 193 aa. The genetic ontology and pathway analysis of this gene revealed its key regulatory role in the following cellular signaling pathways: identical protein binding, protein binding involved in protein folding, protein homodimerization activity, protein kinase C-binding protein kinase C, and inhibitory activity. HSPB1 or HSP27 has been shown to be implicated in a variety of stress resistance without limb features. HSPB1 has also been reported to provide greater protection when attached to the cytoskeleton as large oligomers or by phosphorylation as monomers, thereby further protecting HSPs cells. As long as there is heat stress in this experiment, there are stronger signals in the core of HSPB1 than in the cytoplasm of myocardial cells (De Graauw et al. 2005). As an oligomer, HSPB1 has two different approaches to stressors (Rogalla et al. 1999), and it is believed that non-phosphorylated HSPB1 could stabilize skeletal components such as actin with its chaperone function. Under certain conditions, this HSPB1 oligomer is separated into phosphorylated diameters. Phosphorylated HSPB1, which may be involved in cell death signaling pathways, is a potential anti-apoptotic molecule. Heat stress or ATP depletion cause HSPB1 to form insoluble structures in the core of large detergents (6106 kDa), which are visible as granules and also contain heat-repellent proteins. Therefore, the protective role of HSPB1 is also regulated by phosphorylation and transfer (Creagh et al. 2000; Paulat, 2016; Tang et al. 2016)

 

The HSPB9 gene-gene ID: 428310

Heat Shock Protein Family B (Small) Member 9 (HSPB9) is a constitutive protection against environmental pollution during blastoderm dormancy. This gene was in chromosome 27 chicken genome and has 1 exon and 171 aa. Luo et al. (2014) investigated the gene expression of chickens under heat stress with the profile chip technology and found significant differences in the expression of the HSPB9 (HSP25) gene in various tissues such as the brain, liver and leg muscles. The HSPB9 gene is located on chromosome 27, which has 993 open pairs, and its mRNA sequence consists of 194 amino acids (the NCBI Gallus gallus genome database). Normally, HSPB9 is not expressed and is only induced in all embryonic tissues of the chicken under thermal stress. These HSPs behave differently than other HSPs and bind to non-native proteins, protecting them from heat stress and preparing them for use with the HSP70 system (Lee and Vierling, 2000). In simulation studies on the expression of HSPB9, it was found that moderate amounts of this HSP play a repressive role against HSPB1 and HSPA2, which could explain why HSPB9 is preferentially associated with non-native proteins. One of the properties that causes the rapid expression of this HSP under stressful conditions is the lack of internogenesis.

 

The IL6 gene-gene ID: 395337

Interleukin (6IL6) is a protein that is a candidate gene for stress because it shows the protective immunological response to heat stress by increasing the expression of interleukin-6 (IL-6) and modulating the expression of genes. This gene was found in chromosome 2 chick genome and has 3 exon counts and consisted of 241 aa. Genetic ontology and pathway analysis highlighted their key roles in the following cellular pathways: cytokine activity, growth factor activity, and interleukin-6 receptor binding. In response to chronic heat stress (CHS), an increase in the expression of pro-inflammatory cytokine interleukin 6 (IL-6) and heat shock proteins of 70 KDa (HSP70) has been reported (Al-Zghoul et al. 2019). Cytokines are immune signal proteins that strengthen the cellular protective mechanisms against heat stress-induced inflammation (Hietbrink et al. 2006). IL-6 and IL-1 are anti-inflammatory cytokines that are produced during periods of stress and regulate the acute phase response (APR) to stress. IL-1 produces IL-6 (Weber et al. 2010). IL-6 has proven to be a very important regulator of systemic and localized acute inflammation, mainly through the modulation of non-inflammatory cytokines (Al-Zghoul et al. 2019). Activation of IL-6 improves tissue repair by activating the cytokine IL-8, which plays an important role in wound healing (Wigley and Kaiser, 2003). During stressful periods, IL-6 expression can be induced in various ways. First, damaged cells release HSP70 when exposed to heat stress or when secreted by specialized cells. HSP70 in combination with TLR2 and TLR4 triggers the signal waterfall and peaks when the core factor transcription factor Kappa-B (NF-B) is activated, the latter causing IL-6 expression. The second way of IL-6 induction involves activation of NF-B by regulating the regulation of TNF and IL-1 cytokines. Finally, HSF3 was identified as the third IL-6 induction mechanism due to exposure to environmental stressors. Of course, it should be noted that final IL-6 activation occurs only in poultry. According to some reports, IL-6, which is activated by HSF3 due to heat stress, acts as a heat shock gene in chickens (Al-Zghoul et al. 2019).

 

The KLF2 gene-gene ID: 420148

Kruppel-Like Factor 2 (KLF2), a flow-responsive gene, is a known member of this family that is activated by fluid shear stress in cultured endothelial cells, where it regulates a large number of vasoactive endothelial genes. This gene is placed in chromosome 28 chicken genome and exon counts are 3 and 354 aa. In the venous clip model, there is close communication between the activation of phosphatidylinositol-3-kinase (PI3K), histone esterification, KLF2 transcription and NOS-3 induction (Groenendijk et al. 2007). KLF2 can induce NOS-3 expression and enzymatic activity as described by Sen Banerjee et al. (2004) who also showed that KLF2 regulates endothelial activation in response to proinflammatory stimuli. In addition, some reports showed that KLF2 reduced ET-1 expression and KLF2 also induced NOS-3 expression. It recognizes KLF2 as an inductive molecule between NO and ET-1 production in places with high shear stress. In addition, KLF2 deficiency can be avoided through the use of phenylephrine, which increases vascular tone. KLF2 contains a MEF2 compound in its promoter. The MEF2 family is one of the best properties of extracellular signal regulated kinase 5 (ERK5) and a potent flow-induced factor. In this way, KLF2 expression can be induced.

 

The MEF2C gene-gene ID: 769007

Myocyte Enhancer Factor 2C (MEF2C) is a protein that belongs to the myocyte-specific Enhancer-Binding Factor 2 (MEF2) protein family, which is involved in the development and differentiation of skeletal muscles in vertebrates. This large gene was in the chromosome Z chicken genome and has 17 exon counts and 473 aa. The human MEF2C gene codes for the myocyte-specific enhancer factor 2C protein (Leifer et al. 1993). This protein is a transcription factor in the MEF2 family (Molkentin et al. 1996). Nebreda and Porras (2000) has shown that this gene affects MAPK activity and that phosphorylation and regulation of MEF2C protein activity are influenced by MAPK protein kinases. These kinase proteins are specific for the amino acids serine, threonine and tyrosine and control and direct cellular responses to various stimuli, such as mitogen (mitogen is a chemical that stimulates the cell to initiate cell division and mitosis), osmotic stress, thermal shock and pre-inflammatory cytokines are involved as well as the regulation of cell function, including proliferation, gene expression, differentiation, lung cell survival and apoptosis (Pearson et al. 2001). Typically, two specific events of cellular responses to different types of stress include activation of heat shock drugs (HSFs) and transcriptional activators of these genes and the other activation of JNKs and P38-MAPKinase, known collectively as protein kinases, to be active during stress (Pearson et al. 2001).

 

The SYK gene-gene ID: 427272

Spleen-associated tyrosine kinase (SYK) is essential for platelet activation, which is based on the immune receptor tyrosine-based activation motif (ITAM). This gene was in chromosome Z-Chicken and its exon number is 15 and consisted of 613 aa. Genontology and signaling pathway analyzes showed a remarkable role of this candidate gene in the following cellular signaling: B-cell receptor signaling pathway, B-cell receptor signaling pathway, adaptive immune response, adaptive immune response, blood vessel morphogenesis, cell differentiation, cellular response to hydrogen peroxide, cellular response to Molecules of fungal origin, defense reaction against bacteria, innate immune response, integrin-mediated signaling pathway and leukocyte-cell-cell adhesion. Specific cellular stress such as oxidative stress are powerful activators of the PTKs of the splenic tyrosine kinase (SYK) family in lymphocytes. Stimulus stress can also activate SYK in B cells as well as in humans and chickens (Qin et al. 1997). Spleen Tyrosine Kinase (SYK) (72 kDa protein tyrosine kinase) is an N-terminal tandem pair of SH2 domains separated by a C-terminal catalytic domain.

 

The TRH gene-Gene ID: 414344

The thyrotropin-releasing hormone (TRH) synthesized and secreted by the hypothalamus not only regulates the corresponding hormonal secretion of the pituitary, adrenal and thyroid glands, but also plays an important role in many physiological regulations. The gene architecture for this protein consisted of 7 exons and this candidate gene was located in the chr.12 chicken genome and comprised 260 aa.

 

Table 1 Lists the genes that affect stress and their involved biological pathways

 

Continued Table 1 Lists the genes that affect stress and their involved biological pathways

 

 

Genontology and pathway analysis have highlighted their key roles in the following processes: eating behavior, histamine metabolism, hormone-mediated signaling pathway, negative regulation of glutamate secretion, positive regulation of gamma-aminobutyric acid secretion and positive regulation of insulin secretion. The results show that cold stress can alter TRH mRNA levels in the hypothalamus of broilers (Joseph-Bravo et al. 2016). Cold exposure significantly activates the HPT axis, with increased thyrotropin-releasing hormone (TRH) synthesis, thyroid-stimulating hormone (Rage et al. 1994; Wu et al. 2013). This suggests that cold stress can regulate TRH gene expression at the translational level or after translation. In regulating the expression of TRH gene mRNA expression in the hypothalamus, most studies have shown that negative feedback from thyroid hormones is the most important regulatory mechanism (Kim et al. 1996).

 

The VPS13A gene-gene ID: 427050

The human VPS13A gene codes for the vacuolar protein sorting-associated protein 13A (Rampoldi et al. 2001). The gene also codes for chorein as a key regulator of platelet secretion and accumulation and plays an important role in the production and regulation of platelets (Schmidt et al. 2013). This gain gene was in chromosome Z chicken genome and exon number is 74 exons and 3206 AA. The chorein protein is obtained from a large number of human tissue cells as well as from primary skin fibroblasts and red blood cells. In humans, the platelet count also affects the overall viscosity of the blood. Because thermal stress increases total platelet counts and blood viscosity, which in turn increases physiological damage and the risk of brain and coronary thrombosis, the VPS13A gene may play an important role in coding for chorein. It plays a role in the production and regulation of platelets during heat stress, thereby increasing the body's resistance to heat (DobsonStone et al. 2004). Exposure to acute heat stress also affects birds' behavior by affecting the secretion of stress hormones.

 

Gene ontology (GO) and networking

Gene ontology (GO) and pathway networking of candidate gene associated with stress was loaded into Cytoscape for analysis. String database analysis illustrated role of highlighted gene in multiple cellular task and functionally and pathways.

 

CONCLUSION

Previous research has shown that the effects of stress are observed in a variety of biological pathways. For example, in one of the test chickens, the heat stressed chickens, three hundred and nine different genes were expressed in the testes of chickens with acute heat stress. These various factors were mainly involved in the response to stimuli or stress, metabolism, signal transmission, transcription, transport, and protein metabolic processes. An application network and a qRT-PCR analysis showed that HSP genes and BAP3 antibodies, co-cochaperones (HSP25, HSP90AA1, HSP70 and DNAJA4), SERPINB2 and BAG3 genes are regulated in pressure testicular chicks). Another study used global gene expression analysis to examine the genetic structure of the hypothalamus of chickens exposed to natural temperatures, heat stress and temperature recovery. The expression of heat shock protein families has also shown some changes, particularly in HSPCB and DNAJC13 (Sun et al. 2015). Also, a study in the rate of change in expression of heat shock protein transcription factors after induction of acute and chronic heat stress in laying hens showed that acute and chronic heat stroke causes various oxidative damage and changes in the HSP and HSF genes in the liver, heart and muscles of laying hens. Some work has shown changes in HSP expression in the heart, liver, kidneys, blood, and fleshy muscles. It is important that, in addition to the genes directly or indirectly related to thermal stress in chickens (Table 1), further studies are conducted with these genetic groups in order to establish molecular profiles related to thermal stress and other genes of the HSF and HSP. According to published studies, CRYAB, HSP90AA1, IL6, HSPA2, HSF2, HSPB1, HSF3, PLK1, BAG3 are mostly associated with non-infectious and infectious stressors and may deserve further attention. String database analysis illustrated role of highlighted gene in multiple cellular task and functionally such as ATPase activity, cellular processes, including protection of the proteome from stress, folding and transport of newly synthesized polypeptides, activation of proteolysis of misfolded proteins and the formation and dissociation of protein complexes. Obtained information from Animal QTL database indicated important role of chromosomes 2, 3, 4, 5, 12, 14 and 24 associated with stress resistance and susceptibility. Since these genes are expressed at the beginning of stress-related metabolic pathways, genes play a key role in the development of stress and protective pathways. On this basis, this report seeks to examine most of the genomic regions that control homeostasis and promote cell survival, molecular transport, and cell signaling. Future research is needed to validate the kind of conclusions that can be drawn from this study.

 

ACKNOWLEDGEMENT

We would like to thank Reviewers for taking the necessary time and effort to review the manuscript.

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