Project description:Our previous study had shown that chronic corticosterone (CORT) exposure causes excessive fat deposition in chicken liver, yet it remains unknown whether it is associated with inflammation and fibrosis. In general, heat shock proteins (HSPs) are activated in response to acute stress to play a cytoprotective role, and this activation is associated with m<sup>6</sup>A-mediated post-transcriptional regulation. However, changes of HSPs and the m<sup>6</sup>A methylation on their mRNAs in response to chronic CORT treatment in chicken liver have not been reported. In this study, chronic CORT exposure induced inflammation and fibrosis in chicken liver, associated with significantly modulated expression of HSPs that was significantly upregulated at mRNA level yet downregulated at protein level. Concurrently, m<sup>6</sup>A methyltransferases METTL3 content was upregulated together with the level of m<sup>6</sup>A methylation on HSPs transcripts. The m<sup>6</sup>A-seq analysis revealed 2-6 significantly (P < 0.05) hypermethylated m<sup>6</sup>A peaks in the mRNA of 4 different species of HSPs in CORT-treated chicken liver. HSP90B1 transcript had 6 differentially methylated m<sup>6</sup>A peaks among which peaks on exon 16 and exon 17 showed 3.14- and 4.72-fold of increase, respectively. Mutation of the 8 predicted m<sup>6</sup>A sites on exon 16 and exon 17 resulted in a significant (P < 0.05) increase in eGFP-fused content of HSP90B1 exon 16 and exon 17 fragment in 293 T cells, indicating a possible role of m<sup>6</sup>A in post-transcriptional regulation of HSPs. In conclusion, chronic CORT exposure induces inflammation and fibrosis in chicken liver along with an increase in the levels and m6A methylation of several HSPs mRNAs; HSPs levels were however reduced under the indicated conditions. Results presented suggest that the reduction in HSPs levels may be associated with m6A methylation in CORT-exposed chickens.
Project description:High-throughput RNA sequencing (RNA-Seq) studies demonstrate that Alter-native Splicing (AS) is a widespread mechanism that enhances transcriptome diversity, particularly in plants exposed to environmental stress. In an attempt to determine the transcriptome and AS patterns of cabbage inbred line "HO" under Heat Stress (HS), RNA-Seq was carried out using HS-treated and con-trol samples. Genome-wide analysis indicated that AS is differentially regulated in response to HS. The number of AS events markedly increased in HS-treated samples compared to the control.We identified 1,864 genes, including Heat shock transcription factor (Hsf) and heat shock protein (Hsp) genes, that exhibited >4-fold changes in expression upon exposure to HS. The enriched Gene Ontology (GO) terms of the 1,864 genes included 'response to stress/abiotic stimulus/chemical stimulus', among, which the genes most highly induced by HS encode small Hsps and Hsf proteins. The heat-induced genes also showed an increased number of AS events under HS conditions. In addi-tion, the distribution of AS types was altered under HS conditions, as the level of Intron Retention (IR) decreased, whereas other types of AS increased, under these conditions. Severe HS-induced AS was al-so observed in Hsfs and Hsps, which play crucial roles in regulating heat tolerance. Our results support the notion that AS of HS-related genes, such as HsfA2 and HsfB2a, are important for heat stress adapta-tion in cabbage.
Project description:Heat stress triggers an evolutionarily conserved set of responses in cells. The transcriptome responds to hyperthermia by altering expression of genes to adapt the cell or organism to survive the heat challenge. RNA-seq technology allows rapid identification of environmentally responsive genes on a large scale. In this study, we have used RNA-seq to identify heat stress responsive genes in the chicken male white leghorn hepatocellular (LMH) cell line. The transcripts of 812 genes were responsive to heat stress (p < 0.01) with 235 genes upregulated and 577 downregulated following 2.5 h of heat stress. Among the upregulated were genes whose products function as chaperones, along with genes affecting collagen synthesis and deposition, transcription factors, chromatin remodelers, and genes modulating the WNT and TGF-beta pathways. Predominant among the downregulated genes were ones that affect DNA replication and repair along with chromosomal segregation. Many of the genes identified in this study have not been previously implicated in the heat stress response. These data extend our understanding of the transcriptome response to heat stress with many of the identified biological processes and pathways likely to function in adapting cells and organisms to hyperthermic stress. Furthermore, this study should provide important insight to future efforts attempting to improve species abilities to withstand heat stress through genome-wide association studies and breeding.
Project description:To study the effect of chronic heat stress on producing laying type hens, RNA-Seq was performed on liver samples during a 4-week heat stress experiment. RNA-Seq samples were collected 3-hour, 2-weeks, and 4-weeks post heat from both control (unheated) and treatment (heated) birds. RNA was extracted from the tissues with mirVana miRNA Isolation Kit, treated with DNase, and mRNA cDNA libary were prepared with Illumina TrueSeq Stranded mRNA Library Prep Kit. Sequencing was done on 4 lanes with 12 libraries per lane on Illumina HiSeq 3000 platform.
Project description:Two environmental factors, Newcastle disease and heat stress, are concurrently negatively impacting poultry worldwide and warrant greater attention into developing genetic resistance within chickens. Using two genetically distinct and highly inbred layer lines, Fayoumi and Leghorn, we explored how different genetic backgrounds affect the bursal response to a treatment of simultaneous Newcastle disease virus (NDV) infection at 6 days postinfection (dpi) while under chronic heat stress. The bursa is a primary lymphoid organ within birds and is crucial for the development of B cells. We performed RNA-seq and ChIP-seq targeting histone modifications on bursa tissue. Differential gene expression revealed that Leghorn, compared to Fayoumi, had significant down-regulation in genes involved in cell proliferation, cell cycle, and cell division. Interestingly, we also found greater differences in histone modification levels in response to treatment in Leghorns than Fayoumis, and biological processes enriched in associated target genes of H3K27ac and H3K4me1 were similarly associated with cell cycle and receptor signaling of lymphocytes. Lastly, we found candidate variants between the two genetic lines within exons of differentially expressed genes and regulatory elements with differential histone modification enrichment between the lines, which provides a strong foundation for understanding the effects of genetic variation on NDV resistance under heat stress. This study provides further understanding of the cellular mechanisms affected by NDV infection under heat stress in chicken bursa and identified potential genes and regulatory regions that may be targets for developing genetic resistance within chickens.
Project description:Chicken products are the most consumed animal-sourced foods at a global level across greatly diverse cultures, traditions, and religions. The consumption of chicken meat has increased rapidly in the past few decades and chicken meat is the main animal protein source in developing countries. Heat stress is one of the environmental factors which decreases the productive performance of poultry and meat quality. Heat stress produces the over-expression of heat shock factors and heat shock proteins in chicken tissues. Heat shock proteins regulate several molecular pathways in cells in response to stress conditions, changing the homeostasis of cells and tissues. These changes can affect the physiology of the tissue and hence the production ability of chickens. Indeed, commercial chicken strains can reach a high production level, but their body metabolism, being comparatively accelerated, has poor thermoregulation. In contrast, native backyard chickens are more adapted to the environments in which they live, with a robustness that allows them to survive and reproduce constantly. In the past few years, new molecular tools have been developed, such as RNA-Seq, Single Nucleotide Polymorphisms (SNPs), and bioinformatics approaches such as Genome-Wide Association Study (GWAS). Based on these genetic tools, many studies have detected the main pathways involved in cellular response mechanisms. In this context, it is necessary to clarify all the genetic and molecular mechanisms involved in heat stress response. Hence, this paper aims to review the ability of the new generation of genetic tools to clarify the molecular pathways associated with heat stress in chickens, offering new perspectives for the use of these findings in the animal breeding field.