Cortactin has an essential and specific role in osteoclast actin assembly

Shandiz Tehrani, Roberta Faccio, Indra Chandrasekar, F. Patrick Ross, John A. Cooper

Research output: Contribution to journalArticle

98 Scopus citations

Abstract

Osteoclasts are essential for bone dynamics and calcium homeostasis. The cells form a tight seal on the bone surface, onto which they secrete acid and proteases to resorb bone. The seal is associated with a ring of actin filaments. Cortactin, a c-Src substrate known to promote Arp2/3-mediated actin assembly in vitro, is expressed in osteoclasts and localizes to the sealing ring. To address the role of cortactin and actin assembly in osteoclasts, we depleted cortactin by RNA interference. Cortactin-depleted osteoclasts displayed a complete loss of bone resorption with no formation of sealing zones. On nonosteoid surfaces, osteoclasts flatten with a dynamic, actin-rich peripheral edge that contains podosomes, filopodia, and lamellipodia. Cortactin depletion led to a specific loss of podosomes, revealing a tight spatial compartmentalization of actin assembly. Podosome formation was restored in cortactin-depleted cells by expression of wild-type cortactin or a Src homology 3 point mutant of cortactin. In contrast, expression of a cortactin mutant lacking tyrosine residues phosphorylated by Src did not restore podosome formation. Cortactin was found to be an early component of the nascent podosome belt, along with dynamin, supporting a role for cortactin in actin assembly.

Original languageEnglish (US)
Pages (from-to)2882-2895
Number of pages14
JournalMolecular Biology of the Cell
Volume17
Issue number7
DOIs
Publication statusPublished - Jul 2006
Externally publishedYes

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ASJC Scopus subject areas

  • Molecular Biology
  • Genetics
  • Cell Biology

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