OASIS overexpression in murine podocyte cell line

Podocyte injury is involved in the onset and progression of various kidney diseases. We previously demonstrated that the transcription factor, old astrocyte specifically induced substance (OASIS) in myofibroblasts, contributes to kidney fibrosis, as a novel role of OASIS in the kidneys. Importantly, we found that OASIS is also expressed in podocytes; however, the pathophysiological significance of OASIS in podocytes remains unknown. Upon lipopolysaccharide (LPS) treatment, there is an increase in OASIS in murine podocytes. Enhanced serum creatinine levels and tubular injury, but not albuminuria and podocyte injury, are attenuated upon podocyte-restricted OASIS knockout in LPS-treated mice, as well as diabetic mice. The protective effects of podocyte-specific OASIS deficiency on tubular injury are mediated by protein kinase C iota (PRKCI/PKCι), which is negatively regulated by OASIS in podocytes. Furthermore, podocyte-restricted OASIS transgenic mice show tubular injury and tubulointerstitial fibrosis, with severe albuminuria and podocyte degeneration. Finally, there is an increase in OASIS-positive podocytes in the glomeruli of patients with minimal change nephrotic syndrome and diabetic nephropathy. Taken together, OASIS in podocytes contributes to podocyte and/or tubular injury, in part through decreased PRKCI. The induction of OASIS in podocytes is a critical event for the disturbance of kidney homeostasis. We searched for genes whose expression is induced by the transcription factor OASIS in podocytes. Murine cultured podocytes were transfected with a lentivirus expressing the active form of Oasis/Creb3l1 or venus for 24 h. Post the lentiviral infection, the medium was changed to RPMI-1640 with 10% FBS. Forty-eight hours after treatment with the lentiviral vectors, total RNA was extracted from the OASIS-overexpressing podocytes, using the RNeasy® mini kit (Qiagen, Venlo, Netherlands). Gene expression was analyzed using the SurePrint G3 Mouse GE v2 8×60K Microarray (Agilent Technologies, Santa Clara, CA, USA).