Lipid phosphatases identified by screening a mouse phosphatase shRNA library regulate T-cell differentiation and Protein kinase B AKT signaling

Abstract

Screening a complete mouse phosphatase lentiviral shRNA library using high-throughput sequencing revealed several phosphatases that regulate CD4 T-cell differentiation.We concentrated on twolipid phosphatases, the myotubularin-related protein (MTMR)9 and -7. Silencing MTMR9 by shRNA or siRNA resulted in enhanced T-helper (Th)1 differentiation and increased Th1 protein kinase B (PKB)/AKT phosphorylation while silencing MTMR7 caused increased Th2 and Th17 differentiation and increased AKT phosphorylation in these cells. Irradiated mice reconstituted with MTMR9 shRNA-transduced bonemarrow cells had an elevated proportion of T-box transcription factor T-bet expressors among their CD4 T cells. After adoptive transfer of naive cells fromsuch reconstituted mice, immunization resulted in a greater proportion of T-box transcription factor T-bet-expressing cells. Thus, myotubularin-related proteins have a role in controlling in vitro and in vivo Th-cell differentiation, possibly through regulation of phosphatidylinositol [3,4,5]-trisphosphate activity.