P47. NPR-A is essential for embryonic stem cell self-renewal and pluripotency

Abstract

The self-renewal and pluripotency of embryonic stem (ES) cells are maintained by several signaling cascades and by expression of intrinsic factors, such as Oct4, Nanog and Sox2. The mechanism that regulates these signaling cascades in ES cells is of great interest. We have recently showed that natriuretic peptide receptor A (NPR-A), which is a specific receptor for atrial and brain natriuretic peptide (ANP and BNP), is expressed in preimplantation embryos and in murine ES cells. In this study, we examined whether NPR-A is involved in the maintenance of ES cell pluripotency. Targeting of NPR-A with short interfering RNA (siRNA) resulted in phenotypic changes indicative of differentiation, downregulation of self-renewal and pluripotency factors (Oct4, Nanog and Sox2), and upregulation of differentiation genes. NPR-A knockdown also resulted in a marked downregulation of phosphorylated Akt, which is essential for ES cell self-renewal. Furthermore, NPR-A knockdown induced accumulation of ES cells in the G1-phase of the cell cycle. Interestingly, we found that ANP was expressed in self-renewing ES cells, whereas its level was reduced after ES cell differentiation by the withdrawal of leukemia inhibitory factor. Treatment of ES cells with exogenous ANP upregulated the expression of Oct4 and Nanog, and this upregulation depended on NPR-A signaling, because it was completely reversed by pretreatment with NPR-A antagonist or cGMP-dependent protein kinase inhibitor. Also, ANP increased the expression level of phosphorylated Akt. These findings provide a novel role for NPR-A in the maintenance of self-renewal and pluripotency of ES cells.