Inositol 1, 3, 4, 5-tetrakisphosphate controls proapoptotic Bim gene expression and survival in B cells

Y Maréchal, X Pesesse, Y Jia… - Proceedings of the …, 2007 - National Acad Sciences
Y Maréchal, X Pesesse, Y Jia, V Pouillon, D Pérez-Morga, J Daniel, S Izui, PJ Cullen, O Leo
Proceedings of the National Academy of Sciences, 2007National Acad Sciences
The contribution of the B isoform of inositol 1, 4, 5-trisphosphate [Ins (1, 4, 5) P 3] 3-kinase
(or Itpkb) and inositol 1, 3, 4, 5-tetrakisphosphate [Ins (1, 3, 4, 5) P 4], its reaction product, to
B cell function and development remains unknown. Here, we show that mice deficient in
Itpkb have defects in B cell survival leading to specific and intrinsic developmental
alterations in the B cell lineage and antigen unresponsiveness in vivo. The decreased B cell
survival is associated with a decreased phosphorylation of Erk1/2 and increased Bim gene …
The contribution of the B isoform of inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] 3-kinase (or Itpkb) and inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P4], its reaction product, to B cell function and development remains unknown. Here, we show that mice deficient in Itpkb have defects in B cell survival leading to specific and intrinsic developmental alterations in the B cell lineage and antigen unresponsiveness in vivo. The decreased B cell survival is associated with a decreased phosphorylation of Erk1/2 and increased Bim gene expression. B cell survival, development, and antigen responsiveness are normalized in parallel to reduced expression of Bim in Itpkb−/− Bim+/− mice. Analysis of the signaling pathway downstream of Itpkb revealed that Ins(1,3,4,5)P4 regulates subcellular distribution of Rasa3, a Ras GTPase-activating protein acting as an Ins(1,3,4,5)P4 receptor. Together, our results indicate that Itpkb and Ins(1,3,4,5)P4 mediate a survival signal in B cells via a Rasa3–Erk signaling pathway controlling proapoptotic Bim gene expression.
National Acad Sciences