Whole genome level analysis of the DEATH protein superfamily in sheep (Ovis aries) and their coordination relationship in regulating lactation

Abstract

Background Sheep milk is a nutritional and health-promoting food source for humans. The DEATH superfamily is a conserved protein family, and some of its members are closely related to lactation. Systematic studies of the members of the DEATH superfamily are important for further understanding its functions in the mammary gland during lactation; however, there studies are currently lacking. Results Herein, 74 members of the DEATH superfamily were identified in sheep, and phylogenetic analyses indicated that four subfamilies were strongly correlated in evolution. The Ka/Ks calculations demonstrated that negative selection was the primary pressure acting on DEATH members; however, the immune-related gene IFI203 was undergoing strong positive selection in sheep. Furthermore, in the late pregnancy and lactation period, these DEATH genes exhibited similar expression patterns under different nutritional conditions in the mammary gland, and four subfamilies were positively correlated in expression patterns. Additionally, half or more DEATH genes were upregulated in the lactation period, which implied their crucial roles in the lactation of sheep. Conclusions The current research contributes to a better understanding of the evolutionary characteristics of the DEATH superfamily and their roles in sheep lactation, and it also provides potential target genes for the molecular breeding of dairy sheep. Graphical Abstract