title: Regulation of the formation of osteoclastic actin rings by proline-rich tyrosine kinase 2 interacting with gelsolin.
abstract: Osteoclast activation is important for bone remodeling and is altered in multiple bone disorders. This process requires cell adhesion and extensive actin cytoskeletal reorganization. Proline-rich tyrosine kinase 2 (PYK2), a major cell adhesion-activated tyrosine kinase in osteoclasts, plays an important role in regulating this event. The mechanisms by which PYK2 regulates actin cytoskeletal organization and osteoclastic activation remain largely unknown. In this paper, we provide evidence that PYK2 directly interacts with gelsolin, an actin binding, severing, and capping protein essential for osteoclastic actin cytoskeletal organization. The interaction is mediated via the focal adhesion-targeting domain of PYK2 and an LD motif in gelsolin's COOH terminus. PYK2 phosphorylates gelsolin at tyrosine residues and regulates gelsolin bioactivity, including decreasing gelsolin binding to actin monomer and increasing gelsolin binding to phosphatidylinositol lipids. In addition, PYK2 increases actin polymerization at the fibroblastic cell periphery. Finally, PYK2 interacts with gelsolin in osteoclasts, where PYK2 activation is required for the formation of actin rings. Together, our results suggest that PYK2 is a regulator of gelsolin, revealing a novel PYK2-gelsolin pathway in regulating actin cytoskeletal organization in multiple cells, including osteoclasts.
authors.affiliation: Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
authors.forename: Yi
authors.initials: Y
authors.lastname: Xie
authors.forename: Quan-Sheng
authors.initials: QS
authors.lastname: Du
authors.forename: Xiao-Jun
authors.initials: XJ
authors.lastname: Wu
authors.forename: Xu
authors.initials: X
authors.lastname: Feng
authors.forename: Lin
authors.initials: L
authors.lastname: Mei
authors.forename: Jay M
authors.initials: JM
authors.lastname: McDonald
authors.forename: Wen-Cheng
authors.initials: WC
authors.lastname: Xiong
mesh_terms: D000199:Actins / Q000378:metabolism*; D020816:Amino Acid Motifs; D000818:Animals; D002448:Cell Adhesion / Q000502:physiology; D002460:Cell Line; D003599:Cytoskeleton / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D005456:Fluorescent Dyes / Q000378:metabolism; D051418:Focal Adhesion Kinase 2; D018260:Gelsolin / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D010010:Osteoclasts / Q000166:cytology / Q000502:physiology*; D010590:Phalloidine / Q000378:metabolism; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020798:Two-Hybrid System Techniques
chemical_list: D000199:Actins; D005456:Fluorescent Dyes; D018260:Gelsolin; D019269:Phosphatidylinositol 4,5-Diphosphate; D011993:Recombinant Fusion Proteins; D010590:Phalloidine; D011505:Protein-Tyrosine Kinases; D051418:Focal Adhesion Kinase 2; C496053:Ptk2b protein, mouse