PYK2 in osteoclasts is an adhesion kinase, localized in the sealing zone, activated by ligation of alpha(v)beta3 integrin, and phosphorylated by src kinase

Osteoclast activation is initiated by adhesion to the bone surface, followed by cytoskeletal rearrangement, the formation of the sealing zone, and a polarized ruffled membrane. This study shows that PYK2/CAKbeta/RAFTK, a cytoplasmic kinase related to the focal adhesion kinase, is highly expressed in...

Full description

Saved in:
Bibliographic Details
Published in:The Journal of clinical investigation 1998-09, Vol.102 (5), p.881-892
Main Authors: Duong, L T, Lakkakorpi, P T, Nakamura, I, Machwate, M, Nagy, R M, Rodan, G A
Format: Article
Language:English
Subjects:
Animals
Bone Marrow Cells - metabolism
Bone Resorption - metabolism
Cell Adhesion - physiology
Cell Adhesion Molecules - physiology
Cell Line
Cholecalciferol - pharmacology
Coculture Techniques
Enzyme Activation - physiology
Extracellular Matrix Proteins - metabolism
Focal Adhesion Kinase 1
Focal Adhesion Kinase 2
Focal Adhesion Protein-Tyrosine Kinases
Gene Expression Regulation - genetics
Immunohistochemistry
Mice
Osteoclasts - enzymology
Phosphorylation
Protein-Tyrosine Kinases - physiology
Receptors, Vitronectin - metabolism
RNA, Messenger - metabolism
src Homology Domains - physiology
src-Family Kinases - metabolism
Tyrosine - metabolism
Citations: Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Osteoclast activation is initiated by adhesion to the bone surface, followed by cytoskeletal rearrangement, the formation of the sealing zone, and a polarized ruffled membrane. This study shows that PYK2/CAKbeta/RAFTK, a cytoplasmic kinase related to the focal adhesion kinase, is highly expressed in rat osteoclasts in vivo. Using murine osteoclast-like cells (OCLs) or their mononuclear precursors (pOCs), generated in a coculture of bone marrow and osteoblastic MB1.8 cells, we show: (a) tyrosine phosphorylation of PYK2 upon ligation of beta3 integrins or adhesion of pOCs to serum, vitronectin, osteopontin, or fibronectin but not to laminin or collagen; (b) coimmunoprecipitation of PYK2 and c-Src from OCLs; (c) PYK2 binding to the SH2 domains of Src; (d) marked reduction in tyrosine phosphorylation and kinase activity of PYK2 in OCLs derived from Src (-/-) mice, which do not form actin rings and do not resorb bone; (e) PYK2 phosphorylation by exogeneous c-Src; (f) translocation of PYK2 to the Triton X-100 insoluble cytoskeletal fraction upon adhesion; (g) localization of PYK2 in podosomes and the ring-like structures in OCLs plated on glass and in the sealing zone in OCLs plated on bone; and (h) activation of PYK2, in the presence of MB1.8 cells, parallels the formation of sealing zones and pit resorption in vitro and is reduced by echistatin or calcitonin and cytochalasin D. Taken together, these findings suggest that Src-dependent tyrosine phosphorylation of PYK2 is involved in the adhesion-induced formation of the sealing zone, required for osteoclastic bone resorption.
ISSN:0021-9738
1558-8238
DOI:10.1172/jci3212