Comparative transcriptomic analysis reveals the important role of hepatic fatty acid metabolism in the acute heat stress response in chickens

Abstract

Background: Heat stress poses a major challenge to global poultry production, but the molecular mechanisms driving the acute heat stress response in multiple organs of chickens remain poorly understood. The present study aimed to elucidate these mechanisms by establishing an acute heat stress chicken model and analyzing the multi-tissue transcriptome and physiological responses.

Results: Exposure to 36℃ for 6 h induced marked physiological changes, including elevated rectal temperatures, severe multi-organ damage, and disrupted energy metabolism (increased serum glucose [GLU] and decreased triglycerides [TG] and total cholesterol [TCHO]). Comparative transcriptomic analysis of heart, liver, spleen, lung, and kidney tissues revealed tissue-specific differential gene expression, with the liver and heart showing the highest number of differentially expressed genes (DEGs). KEGG enrichment analyses identified lipid metabolism pathways that are key to the multi-tissue acute heat stress response. Weighted gene co-expression network analysis (WGCNA) further identified 58 differentially modularized hub genes (DMHGs), of which 42 were hepatic differentially expressed genes, and most of these DMHGs were significantly enriched for fatty acid metabolic pathways. Fatty acid metabolic pathway-associated DMHGs were significantly correlated with rectal temperature, serum GLU, TG, lactate dehydrogenase (LDH), and aspartate aminotransferase (AST). Functional validation in primary hepatocytes demonstrated that overexpression of FASN attenuated heat stress-induced reductions in triglyceride levels.

Conclusions: The critical role of hepatic fatty acid metabolism in mediating the acute heat stress response in chickens was revealed by a multi-tissue comparative transcriptome, and it was determined that FASN provides actionable insights into improving heat tolerance in poultry through metabolic interventions.

Keywords: Chicken; Fatty acid metabolism; Fatty acid synthase; Heat stress; Transcriptomics.

Fig. 1

Effects of acute heat stress on physiological parameters and organ histopathology in chickens. A Rectal temperature. B Representative histopathological images of major organs (heart, liver, spleen, lungs and kidneys) of chickens from control (ambient temperature) and heat-stressed groups (36 ℃, 6 h). C Serum indicators of tissue damage: creatine kinase (CK), lactate dehydrogenase (LDH) and aspartate aminotransferase (AST). D Serum metabolic indicators: glucose (GLU), total protein (TP), triglyceride (TG) and total cholesterol (TCHO). * P < 0.05; ** P < 0.01

Fig. 2

Transcriptome analysis of chicken tissues to acute heat stress. A Principal component analysis plot of RNA-seq data from heart, liver, spleen, lung and kidney tissues of control and heat-stressed chickens. B Number of differentially expressed genes (DEGs) in each tissue of control and heat-stressed chickens. C Venn diagram of the overlap of DEGs among different tissues

Fig. 3

Functional enrichment analysis of differentially expressed genes in chicken tissues in response to acute heat stress. A Top 10 significantly enriched gene ontology (GO) terms in heart, liver and kidney tissue bioprocesses. B KEGG secondary classification chart in heart, liver, kidney and spleen tissues

Fig. 4

Weighted gene co-expression network analysis (WGCNA) and functional enrichment of key genes in acute heat-stressed chicken tissues. A Heat map of correlation between co-expressed gene modules and tissue heat stress status. B KEGG pathway enrichment analysis of differential module hub genes (DMHGs). C Heatmap of correlation between DMHGs expression levels (FPKM values) and physiological parameters in liver. *P < 0.05, **P < 0.01. D qPCR validation of RNA-seq results of DMHGs (n = 5 per group). E RT-qPCR analysis of FASN expression in control and heat-stressed primary hepatocytes. F Effect of FASN overexpression on LDH, TG, AST and ALT levels in supernatants of control and heat-stressed primary hepatocyte cultures. Data are expressed as mean ± SEM (n = 3 per group). *P < 0.05, **P < 0.01. Different letters indicate significant differences between treatments (P < 0.05)