Transcriptomic Prediction of Pig Functions in a Liver Cell Line.

The newly identified liver-enriched gene 1 () encodes a protein with a characteristic domain of unknown function 781 (DUF781/LEG1), constituting a protein family with only one member in mammals. A functional study in zebrafish suggested that genes are involved in liver development, while the platypus homolog, Monotreme Lactation Protein (), which is enriched in the mammary gland and milk, acts as an antibacterial substance. However, no functional studies on eutherian have been published to date. Thus, we here report the first functional prediction study at the cellular level. As previously reported, eutherian can be classified into three paralogous groups. Pigs have all three genes (), while humans and mice have retained only . Hence, might represent an ideal model for studying gene functions. RNA-seq was performed by the overexpression of and platypus in HepG2 cells. Enrichment analysis showed that and might exhibit little function in liver cells; however, is probably involved in the endoplasmic reticulum (ER) stress response and protein folding. Additionally, gene set enrichment analysis revealed that platypus shows antibacterial activity, confirming the functional study in platypus. Therefore, our study showed from the transcriptomic perspective that mammalian have different functions in liver cells due to the subfunctionalization of paralogous genes.