Process formation of podocytes: Morphogenetic activity of microtubules and regulation by protein serine/threonine phosphatase PP2A

Naoto Kobayashi, Jochen Reiser, Karin Schwarz, Tatsuo Sakai, Wilhelm Kriz, Peter Mundel

Research output: Contribution to journalArticlepeer-review

40 Scopus citations

Abstract

Podocytes possess major processes containing microtubules (MTs) and intermediate filaments and foot processes containing actin filaments (AFs) as core cytoskeletal elements. Although the importance of these cytoskeletal elements for maintaining podocyte processes was previously shown, so far no data are available concerning the developmental regulation of podocyte process formation. A conditionally immortalized mouse podocyte cell line, which can be induced to develop processes similar to those found in vivo, was treated with various reagents to disrupt cytoskeletal elements or to inhibit protein phosphatases. MTs colocalized with vimentin intermediate filaments but not with AFs. After AF disassembly, major processes were maintained, whereas after depolymerization of MTs, podocytes lost their processes, rounded up, and maintained only actin-based peripheral projections. Suppression of MT elongation by nanomolar vinblastine or inhibition of serine/threonine phosphatase PP2A with okadaic acid abolished process formation. PP2A was expressed in undifferentiated but not in differentiated podocytes. One- and two-dimensional western blot analyses revealed a dose-dependent increase in serine/threonine phosphorylation after okadaic acid treatment. Hence, morphogenetic activity of MTs induces podocyte process formation via serine/threonine protein dephosphorylation by PP2A. These results may open new avenues for understanding the signaling mechanism underlying podocyte cytoskeleton alterations during development and in glomerular diseases.

Original languageEnglish (US)
Pages (from-to)255-266
Number of pages12
JournalHistochemistry and Cell Biology
Volume115
Issue number3
DOIs
StatePublished - 2001
Externally publishedYes

Keywords

  • Cytoskeleton
  • Microtubules
  • Podocyte (glomerular epithelial cell)
  • Protein phosphatase type 2A (PP2A)
  • Protein phosphorylation

ASJC Scopus subject areas

  • Histology
  • Molecular Biology
  • Medical Laboratory Technology
  • Cell Biology

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