Silencing the Chicken Seven Transmembrane (Ch-7TM) Receptor Leads to Apoptosis in Chicken Mononuclear Phagocytes

Abstract Background The seven-transmembrane (7TM) receptors are the largest superfamily of cell-surface receptors and are involved in various physiological processes of vertebrate species. In our previous study, a new chicken 7TM receptor (Ch-7TM) was discovered in mononuclear phagocytes (MNPs) derived from chicken peripheral blood mononuclear cells (PBMCs). To explore the functions of Ch-7TM, RNA interference (RNAi) was used to silence the Ch-7TM messenger RNA (mRNA) of MNPs, using small interface RNA (siRNA) designed with BLOCK-iT™ RNAi Designer. Results Herein we demonstrated that silencing of the Ch-7TM mRNA induced apoptosis of MNPs, suggesting that Ch-7TM contributed to the survival of MNPs. Moreover, chicken sera could inhibit the Ch-7TM-silencing-induced apoptosis in MNPs. The survival factor presented in fraction 16 (F16) of chicken sera was highly protective against the Ch-7TM-silencing-induced apoptosis in MNPs. The proteins from fraction 16 (F16) were identified as vitamin D-binding protein and apolipoprotein A-IV (ApoA-IV), which might be potential candidates for survival factors. Conclusions The protective effect of vitamin D and ApoA-IV indicated that Ch-7TM might involve the intracellular oxidation–reduction balance, although more evidence is needed to confirm this function. The siRNA screening serves as an excellent model for studying the functions of chicken MNPs receptors.