title: Role of the polarity protein Scribble for podocyte differentiation and maintenance.
abstract: The kidney filter represents a unique assembly of podocyte epithelial cells that tightly enwrap the glomerular capillaries with their complex foot process network. While deficiency of the polarity proteins Crumbs and aPKC result in impaired podocyte foot process architecture, the function of basolateral polarity proteins for podocyte differentiation and maintenance remained unclear. Here we report, that Scribble is expressed in developing podocytes, where it translocates from the lateral aspects of immature podocytes to the basal cell membrane and foot processes of mature podocytes. Immunogold electron microscopy reveals membrane associated localisation of Scribble predominantly at the basolateral site of foot processes. To further study the role of Scribble for podocyte differentiation Scribble(flox/flox) mice were generated by introducing loxP-sites into the Scribble introns 1 and 8 and these mice were crossed to NPHS2.Cre mice and Cre deleter mice. Podocyte-specific Scribble knockout mice develop normally and display no histological, ultrastructural or clinical abnormalities up to 12 months of age. In addition, no increased susceptibility to glomerular stress could be detected in these mice. In contrast, constitutive Scribble knockout animals die during embryonic development indicating the fundamental importance of Scribble for embryogenesis. Like in podocyte-specific Scribble knockout mice, the development of podocyte foot processes and the slit diaphragm was unaffected in kidney cultures from constitutive Scribble knockout animals. In summary these results indicate that basolateral polarity signaling via Scribble is dispensable for podocyte function, highlighting the unique feature of podocyte development with its significant apical membrane expansions being dominated by apical polarity complexes rather than by basolateral polarity signaling.
authors.affiliation: Renal Division, University Hospital Freiburg, Freiburg, Germany.
authors.forename: Björn
authors.initials: B
authors.lastname: Hartleben
authors.forename: Eugen
authors.initials: E
authors.lastname: Widmeier
authors.forename: Nicola
authors.initials: N
authors.lastname: Wanner
authors.forename: Miriam
authors.initials: M
authors.lastname: Schmidts
authors.forename: Sung Tae
authors.initials: ST
authors.lastname: Kim
authors.forename: Lisa
authors.initials: L
authors.lastname: Schneider
authors.forename: Britta
authors.initials: B
authors.lastname: Mayer
authors.forename: Dontscho
authors.initials: D
authors.lastname: Kerjaschki
authors.forename: Jeffrey H
authors.initials: JH
authors.lastname: Miner
authors.forename: Gerd
authors.initials: G
authors.lastname: Walz
authors.forename: Tobias B
authors.initials: TB
authors.lastname: Huber
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D002478:Cells, Cultured; D047108:Embryonic Development / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D007678:Kidney Glomerulus / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure; D051379:Mice; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins; D050199:Podocytes / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure; D051381:Rats; D017208:Rats, Wistar; D012795:Sialoglycoproteins / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D012795:Sialoglycoproteins; C472451:Pard3 protein, rat; C001643:podocalyxin; C508433:scrib protein, mouse