α-Actinin-4/FSGS1 is required for Arp2/3-dependent actin assembly at the adherens junction

Research output: Contribution to journalArticle

Abstract

We have developed an in vitro assay to study actin assembly at cadherin-enriched cell junctions. Using this assay, we demonstrate that cadherin-enriched junctions can polymerize new actin filaments but cannot capture preexisting filaments, suggesting a mechanism involving de novo synthesis. In agreement with this hypothesis, inhibition of Arp2/3-dependent nucleation abolished actin assembly at cell-cell junctions. Reconstitution biochemistry using the in vitro actin assembly assay identified α-actinin-4/focal segmental glomerulosclerosis 1 (FSGS1) as an essential factor. α-Actinin-4 specifically localized to sites of actin incorporation on purified membranes and at apical junctions in Madin-Darby canine kidney cells. Knockdown of α-actinin-4 decreased total junctional actin and inhibited actin assembly at the apical junction. Furthermore, a point mutation of α-actinin-4 (K255E) associated with FSGS failed to support actin assembly and acted as a dominant negative to disrupt actin dynamics at junctional complexes. These findings demonstrate that α-actinin-4 plays an important role in coupling actin nucleation to assembly at cadherin-based cell-cell adhesive contacts.

Original languageEnglish (US)
Pages (from-to)115-130
Number of pages16
JournalJournal of Cell Biology
Volume196
Issue number1
DOIs
StatePublished - Jan 1 2012

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Actinin
Adherens Junctions
Actins
Cadherins
Intercellular Junctions
Segmental glomerulosclerosis
Madin Darby Canine Kidney Cells
Actin Cytoskeleton
Point Mutation
Adhesives
Biochemistry

ASJC Scopus subject areas

  • Cell Biology

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α-Actinin-4/FSGS1 is required for Arp2/3-dependent actin assembly at the adherens junction. / Tang, Vivian W.; Brieher, William M.

In: Journal of Cell Biology, Vol. 196, No. 1, 01.01.2012, p. 115-130.

Research output: Contribution to journalArticle

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