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bioRxiv · 10.1101/2021.06.22.449474

PI(4,5)P2 controls slit diaphragm formation and endocytosis in Drosophila nephrocytes

Gass, M.·Borkowsky, S.·Lotz, M.-L.·Schroeter, R.·Nedvetsky, P.·Luschnig, S.·Rohlmann, A.·Missler, M.·Krahn, M. P.
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Abstract

Drosophila nephrocytes are an emerging model system for mammalian podocytes and podocyte-associated diseases. Like podocytes, nephrocytes exhibit characteristics of epithelial cells, but the role of phospholipids in polarization of these cells is yet unclear. In epithelia phosphatidylinositol(4,5)bisphosphate (PI(4,5)P2) and phosphatidylinositol(3,4,5)-trisphosphate (PI(3,4,5)P3) are asymmetrically distributed in the plasma membrane and determine apical-basal polarity. Here we demonstrate that both phospholipids are present in the plasma membrane of nephrocytes, but only PI(4,5)P2 accumulates at slit diaphragms. Knockdown of Skittles, a phosphatidylinositol(4)phosphate 5-kinase, which produces PI(4,5)P2, abolished slit diaphragm formation and led to strongly reduced endocytosis. Notably, reduction in PI(3,4,5)P3 by overexpression of PTEN or expression of a dominant-negative phosphatidylinositol-3-Kinase did not affect nephrocyte function, whereas enhanced formation of PI(3,4,5)P3 by constitutively active phosphatidylinositol-3-Kinase resulted in strong slit diaphragm and endocytosis defects by ectopic activation of the Akt/mTOR pathway. Thus, PI(4,5)P2 but not PI(3,4,5)P3 is essential for slit diaphragm formation and nephrocyte function. However, PI(3,4,5)P3 has to be tightly controlled to ensure nephrocyte development.

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Gass, M., Borkowsky, S., Lotz, M.-L., Schroeter, R., Nedvetsky, P., Luschnig, S., Rohlmann, A., Missler, M., Krahn, M. P.. 2021-06-22. PI(4,5)P2 controls slit diaphragm formation and endocytosis in Drosophila nephrocytes. https://doi.org/10.1101/2021.06.22.449474

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