Comparative gene expression profiling of milk somatic cells of Sahiwal cattle and Murrah buffaloes.

India is the world's largest milk producing country because of massive contribution made by cattle and buffaloes. In the present investigation, comprehensive comparative profiling of transcriptomic landscape of milk somatic cells of Sahiwal cattle and Murrah buffaloes was carried out. Genes with highest transcript abundance in both species were enriched for biological processes such as lactation, immune response, cellular oxidant detoxification and response to hormones. Analysis of differential expression identified 377 significantly up-regulated and 847 significantly down-regulated genes with fold change >1.5 in Murrah buffaloes as compared to Sahiwal cattle (p <0.05). Marked enrichment of innate and adaptive immune response related GO terms and higher expression of genes for various host defense peptides such as lysozyme, defensin β and granzymes were evident in buffaloes. Genes related to ECM-receptor interaction, complement and coagulation cascades, cytokine-cytokine receptor interaction and keratinization pathway showed more abundant expression in cattle. Network analysis of the up-regulated genes delineated highly connected genes representing immunity and haematopoietic cell lineage (CBL, CD28, CD247, PECAM1 and ITGA4). For the down-regulated dataset, genes with highest interactions were KRT18, FGFR1, GPR183, ITGB3 and DKK3. Our results lend support to more robust immune mechanisms in buffaloes, possibly explaining lower susceptibility to mammary infections as compared to cattle.