Dissociation of Crk-associated substrate from the vimentin network is regulated by p21-activated kinase on ACh activation of airway smooth muscle.
The intermediate filament protein vimentin has been shown to be required for smooth muscle contraction. The adapter protein p130 Crk-associated substrate (CAS) participates in the signaling processes that regulate force development in smooth muscle. However, the interaction of vimentin filaments with CAS has not been well elucidated. In the present study, ACh stimulation of tracheal smooth muscle strips increased the ratio of soluble to insoluble vimentin (an index of vimentin disassembly) in association with force development. ACh activation also induced vimentin phosphorylation at Ser(56) as assessed by immunoblot analysis. More importantly, CAS was found in the cytoskeletal vimentin fraction, and the amount of CAS in cytoskeletal vimentin was reduced in smooth muscle strips on contractile stimulation. CAS redistributed from the myoplasm to the periphery during ACh activation of smooth muscle cells. The ACh-elicited decrease in CAS distribution in cytoskeletal vimentin was attenuated by the downregulation of p21-activated kinase (PAK) 1 with antisense oligodeoxynucleotides. Vimentin phosphorylation at this residue, the ratio of soluble to insoluble vimentin, and active force in smooth muscle strips induced by ACh were also reduced in PAK-depleted tissues. These results suggest that PAK may regulate CAS release from the vimentin intermediate filaments by mediating vimentin phosphorylation at Ser(56) and the transition of cytoskeletal vimentin to soluble vimentin. The PAK-mediated dissociation of CAS from the vimentin network may participate in the cellular processes that affect active force development during ACh activation of tracheal smooth muscle tissues.
Wang
Ruping
R
Center for Cardiovascular Sciences, Albany Medical College, 47 New Scotland Ave., MC-8, Albany, NY 12208, USA.
Li
Qing-Fen
QF
Anfinogenova
Yana
Y
Tang
Dale D
DD
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D001483:Base Sequence; D050719:Crk-Associated Substrate Protein / Q000378:metabolism*; D004285:Dogs; D066298:In Vitro Techniques; D008954:Models, Biological; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism*; D020319:Oligodeoxyribonucleotides, Antisense / Q000235:genetics; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D012995:Solubility; D014132:Trachea / Q000187:drug effects* / Q000378:metabolism*; D014746:Vimentin / Q000378:metabolism*; D054462:p21-Activated Kinases
D050719:Crk-Associated Substrate Protein; D020319:Oligodeoxyribonucleotides, Antisense; D014746:Vimentin; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases; D000109:Acetylcholine