Phosphorylation of Nephrin Triggers Ca2+ Signaling by Recruitment and Activation of Phospholipase C-{gamma}1.

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Citation

Harita Y, Kurihara H, Kosako H, Tezuka T, Sekine T, Igarashi T, Ohsawa I, Ohta S, Hattori S

Phosphorylation of Nephrin Triggers Ca2+ Signaling by Recruitment and Activation of Phospholipase C-{gamma}1.

J Biol Chem. 2009 Mar 27;284(13):8951-62. doi: 10.1074/jbc.M806851200. Epub 2009 Jan 29.

PubMed ID
19179337 [ View in PubMed
]
Abstract

A specialized intercellular junction between podocytes, known as the slit diaphragm (SD), forms the essential structural frame-work for glomerular filtration in the kidney. In addition, mounting evidence demonstrates that the SD also plays a crucial role as a signaling platform in physiological and pathological states. Nephrin, the major component of the SD, is tyrosine-phosphorylated by a Src family tyrosine kinase, Fyn, in developing or injured podocytes, recruiting Nck to Nephrin via its Src homology 2 domain to regulate dynamic actin remodeling. Dysregulated Ca(2+) homeostasis has also been implicated in podocyte damage, but the mechanism of how podocytes respond to injury is largely unknown. Here we have identified phospholipase C-gamma1 (PLC-gamma1) as a novel phospho-Nephrin-binding protein. When HEK293T cells expressing a chimeric protein consisting of CD8 and Nephrin cytoplasmic domain (CD) were treated with anti-CD8 and anti-mouse antibodies, clustering of Nephrin and phosphorylation of Nephrin-CD were induced. Upon this clustering, PLC-gamma1 was bound to phosphorylated Nephrin Tyr-1204, which induced translocation of PLC-gamma1 from cytoplasm to the CD8/Nephrin cluster on the plasma membrane. The recruitment of PLC-gamma1 to Nephrin activated PLC-gamma1, as detected by phosphorylation of PLC-gamma1 Tyr-783 and increase in inositol 1,4,5-trisphosphate level. We also found that Nephrin Tyr-1204 phosphorylation triggers the Ca(2+) response in a PLC-gamma1-dependent fashion. Furthermore, PLC-gamma1 is significantly phosphorylated in injured podocytes in vivo. Given the profound effect of PLC-gamma in diverse cellular functions, regulation of the Ca(2+) signaling by Nephrin may be important in modulating the glomerular filtration barrier function.

DrugBank Data that Cites this Article

Polypeptides
NameUniProt ID
Tyrosine-protein kinase FynP06241Details