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Proc Natl Acad Sci U S A. 2014 May 27;111(21):7689-94. doi: 10.1073/pnas.1407351111. Epub 2014 May 14.

Polarized deposition of basement membrane proteins depends on Phosphatidylinositol synthase and the levels of Phosphatidylinositol 4,5-bisphosphate.

Author information

  • 1Howard Hughes Medical Institute and Department of Molecular Biology, Princeton University, Princeton, NJ 08544.
  • 2Howard Hughes Medical Institute and Department of Molecular Biology, Princeton University, Princeton, NJ 08544 schupbac@princeton.edu.

Abstract

The basement membrane (BM), a specialized sheet of the extracellular matrix contacting the basal side of epithelial tissues, plays an important role in the control of the polarized structure of epithelial cells. However, little is known about how BM proteins themselves achieve a polarized distribution. Here, we identify phosphatidylinositol 4,5-bisphosphate (PIP2) as a critical regulator of the polarized secretion of BM proteins. A decrease of PIP2 levels, in particular through mutations in Phosphatidylinositol synthase (Pis) and other members of the phosphoinositide pathway, leads to the aberrant accumulation of BM components at the apical side of the cell without primarily affecting the distribution of apical and basolateral polarity proteins. In addition, PIP2 controls the apical and lateral localization of Crag (Calmodulin-binding protein related to a Rab3 GDP/GTP exchange protein), a factor specifically required to prevent aberrant apical secretion of BM. We propose that PIP2, through the control of Crag's subcellular localization, restricts the secretion of BM proteins to the basal side.

KEYWORDS:

Drosophila; PIK; PTEN; cell polarity; oogenesis

PMID:
24828534
[PubMed - in process]
PMCID:
PMC4040573
[Available on 2014/11/27]

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