title: Notch promotes dynamin-dependent endocytosis of nephrin.
abstract: Notch signaling in podocytes causes proteinuria and glomerulosclerosis in humans and rodents, but the underlying mechanism remains unknown. Here, we analyzed morphologic, molecular, and cellular events before the onset of proteinuria in newborn transgenic mice that express activated Notch in podocytes. Immunohistochemistry revealed a loss of the slit diaphragm protein nephrin exclusively in podocytes expressing activated Notch. Podocyte-specific deletion of Rbpj, which is essential for canonical Notch signaling, prevented this loss of nephrin. Overexpression of activated Notch decreased cell surface nephrin and increased cytoplasmic nephrin in transfected HEK293T cells; pharmacologic inhibition of dynamin, but not depletion of cholesterol, blocked these effects on nephrin, suggesting that Notch promotes dynamin-dependent, raft-independent endocytosis of nephrin. Supporting an association between Notch signaling and nephrin trafficking, electron microscopy revealed shortened podocyte foot processes and fewer slit diaphragms among the transgenic mice compared with controls. These data suggest that Notch signaling induces endocytosis of nephrin, thereby triggering the onset of proteinuria.
authors: The Hospital for Sick Children, Division of Nephrology, Toronto Medical Discover Tower, East Tower, 13-706 101 College Street, Toronto, Ontario M5G 17L, Canada.
authors: Aoife M
authors: AM
authors: Waters
authors: Megan Yi Jun
authors: MY
authors: Wu
authors: Yi-Wei
authors: YW
authors: Huang
authors: Guang Ying
authors: GY
authors: Liu
authors: Doug
authors: D
authors: Holmyard
authors: Tuncer
authors: T
authors: Onay
authors: Nina
authors: N
authors: Jones
authors: Sean E
authors: SE
authors: Egan
authors: Lisa A
authors: LA
authors: Robinson
authors: Tino D
authors: TD
authors: Piscione
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D034281:Dynamins / Q000378:metabolism; D004705:Endocytosis; D057809:HEK293 Cells; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D050199:Podocytes / Q000378:metabolism* / Q000648:ultrastructure; D011507:Proteinuria / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D051880:Receptors, Notch / Q000378:metabolism*; D015398:Signal Transduction; D047392:beta-Cyclodextrins
chemical_list: D008565:Membrane Proteins; D051880:Receptors, Notch; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; C113267:nephrin; D034281:Dynamins