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J Cell Biol. 2010 Aug 9;190(3):407-25. doi: 10.1083/jcb.200911020.

Drosophila Mtm and class II PI3K coregulate a PI(3)P pool with cortical and endolysosomal functions.

Author information

1
Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093, USA.

Erratum in

  • J Cell Biol. 2010 Sep 6;190(5):941.

Abstract

Reversible phosphoinositide phosphorylation provides a dynamic membrane code that balances opposing cell functions. However, in vivo regulatory relationships between specific kinases, phosphatases, and phosphoinositide subpools are not clear. We identified myotubularin (mtm), a Drosophila melanogaster MTM1/MTMR2 phosphoinositide phosphatase, as necessary and sufficient for immune cell protrusion formation and recruitment to wounds. Mtm-mediated turnover of endosomal phosphatidylinositol 3-phosphate (PI(3)P) pools generated by both class II and III phosphatidylinositol 3-kinases (Pi3K68D and Vps34, respectively) is needed to down-regulate membrane influx, promote efflux, and maintain endolysosomal homeostasis. Endocytosis, but not endolysosomal size, contributes to cortical remodeling by mtm function. We propose that Mtm-dependent regulation of an endosomal PI(3)P pool has separable consequences for endolysosomal homeostasis and cortical remodeling. Pi3K68D depletion (but not Vps34) rescues protrusion and distribution defects in mtm-deficient immune cells and restores functions in other tissues essential for viability. The broad interactions between mtm and class II Pi3K68D suggest a novel strategy for rebalancing PI(3)P-mediated cell functions in MTM-related human disease.

PMID:
20696708
PMCID:
PMC2922644
DOI:
10.1083/jcb.200911020
[Indexed for MEDLINE]
Free PMC Article

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