Genome-wide analysis of the heat stress response in dermal fibroblasts of zebu and crossbred cattle

The molecular mechanism underlying the physiology of heat stress in the cattle remains undefined. The present study sought to evaluate mRNA expression profiles in the cultured dermal fibroblast of zebu and crossbred cattle in response to heat stress. In this study, gene expression profiling by micro-array was done in dermal fibroblast of zebu (Tharparkar, n=4) and crossbred (Karan-Fries, n=4) cattle in response to heat stress (44°C, 3 h). Present micro-array platform contains 51338 synthesized oligonucleotide probes corresponding to at least 36713 unigenes. Total 11183 and 8126 genes were deferentially expressed with fold change 2; in detailed 3918 and 3458 genes were up regulated; whereas 7265 and 4668 genes were down regulated in Tharparkar and Karan-Fries, respectively. Randomly selected real-time validation showed that 75.02% correlation with micro-array data. Functional annotation and pathway study of the DEGs reveals that, up-regulated genes significantly (P<0.05) affect the protein processing, NOD like receptor pathways (NLRs), apoptosis and melanogenesis while down regulated genes were significantly (P<0.05) found to associated with apoptosis and cellular homeostasis. Bioinformatics' analysis identified temperature-regulated biological processes and pathways. Biological processes over-represented among the earliest genes induced by temperature stress include regulation of transcription, nucleosome assembly, chromatin organization and protein folding. Gene expression changes include activation of heat shock transcription factors (HSFs), increased expression of heat shock proteins (HSPs) and decreased expression and synthesis of other proteins, immune system activation via extra-cellular secretion of HSPs. These findings may provide insights into the underlying mechanism of physiology of heat stress in zebu and crossbred cattle. In conclusion, the present study showed that heat stress deferentially affects expression of significant number of genes in dermal fibroblast of zebu and crossbred cattle. Further analysis is required to understand their functional role in zebu and crossbred cattle.

Keyword: cDNA micro-array, Dermal fibroblast, Heat stress, Karan-Fries, Tharparkar