The E3 ubiquitin ligase specificity subunit ASB2α targets filamins for proteasomal degradation by interacting with the filamin actin-binding domain

Ziba Razinia, Massimiliano Baldassarre, Mohamed Bouaouina, Isabelle Lamsoul, Pierre G. Lutz, David A. Calderwood

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Filamins are an important family of actin-binding and crosslinking proteins that mediate remodeling of the actin cytoskeleton and maintain extracellular matrix connections by anchoring transmembrane proteins to actin filaments and linking them to intracellular signaling cascades. We recently found that filamins are targeted for proteasomal degradation by the E3 ubiquitin ligase specificity subunit ASBα and that acute degradation of filamins through this ubiquitin-proteasome pathway correlates with cell differentiation. Specifically, in myeloid leukemia cells retinoic-acid-induced expression of ASB2α triggers filamin degradation and recapitulates early events crucial for cell differentiation. ASB2α is thought to link substrates to the ubiquitin transferase machinery; however, the mechanism by which ASB2α interacts with filamin to induce degradation remained unknown. Here, we use cell-based and biochemical assays to show that the subcellular localization of ASB2α to actin-rich structures is dependent on filamin and that the actin-binding domain (ABD) of filamin mediates the interaction with ASB2α. Furthermore, we show that the ABD is necessary and sufficient for ASB2α-mediated filamin degradation. We propose that ASB2α exerts its effect by binding the ABD and mediating its polyubiquitylation, so targeting filamins for degradation. These studies provide the molecular basis for ASB2α-mediated filamin degradation and unravel an important mechanism by which filamin levels can be acutely regulated.
Original languageEnglish
Pages (from-to)2631-2641
Number of pages11
JournalJournal of Cell Science
Volume124
Issue number15
Early online date12 Jul 2011
DOIs
Publication statusPublished - 1 Aug 2011

Keywords

  • animals
  • CHO cells
  • cell line, tumor
  • cells, cultured
  • contractile proteins
  • cricetinae
  • cricetulus
  • fluorescent antibody technique
  • HeLa cells
  • humans
  • immunoblotting
  • mice
  • microfilament proteins
  • proteasome endopeptidase complex
  • protein binding
  • ubiquitin-protein ligases

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