title: Deletion of Calponin 2 in Mouse Fibroblasts Increases Myosin II-Dependent Cell Traction Force.
abstract: Cell traction force (CTF) plays a critical role in controlling cell shape, permitting cell motility, and maintaining cellular homeostasis in many biological processes such as angiogenesis, development, wound healing, and cancer metastasis. Calponin is an actin filament-associated cytoskeletal protein in smooth muscles and multiple types of non-muscle cells. An established biochemical function of calponin is the inhibition of myosin ATPase in smooth muscle cells. Vertebrates have three calponin isoforms. Among them, calponin 2 is expressed in epithelial cells, endothelial cells, macrophages, myoblasts, and fibroblasts and plays a role in regulating cytoskeleton activities such as cell adhesion, migration, and cytokinesis. Knockout (KO) of the gene encoding calponin 2 (Cnn2) in mice increased cell motility, suggesting a function of calponin 2 in modulating CTF. In this study, we examined fibroblasts isolated from Cnn2 KO and wild-type (WT) mice using CTF microscopy. Primary mouse fibroblasts were cultured on polyacrylamide gel substrates embedded with fluorescent beads to measure root-mean-square traction, total strain energy, and net contractile movement. The results showed that calponin 2-null fibroblasts exhibit traction force greater than that of WT cells. Adherent calponin 2-null fibroblasts de-adhered faster than the WT control during mild trypsin treatment, consistent with an increased CTF. Blebbistatin, an inhibitor of myosin II ATPase, is more effective upon an alteration in cell morphology when calponin 2 is present in WT fibroblasts than that on Cnn2 KO cells, indicating their additive effects in inhibiting myosin motor activity. The novel finding that calponin 2 regulates myosin-dependent CTF in non-muscle cells demonstrates a mechanism for controlling cell motility-based functions.
authors.affiliation: Department of Physiology, Wayne State University School of Medicine , Detroit, Michigan 48201, United States.
authors.forename: M Moazzem
authors.initials: MM
authors.lastname: Hossain
authors.affiliation: Departments of Orthopedic Surgery and Bioengineering, University of Pittsburgh , Pittsburgh, Pennsylvania 15213, United States.
authors.forename: Guangyi
authors.initials: G
authors.lastname: Zhao
authors.affiliation: Department of Physiology, Wayne State University School of Medicine , Detroit, Michigan 48201, United States.
authors.forename: Moon-Sook
authors.initials: MS
authors.lastname: Woo
authors.affiliation: Departments of Orthopedic Surgery and Bioengineering, University of Pittsburgh , Pittsburgh, Pennsylvania 15213, United States.
authors.forename: James H-C
authors.initials: JH
authors.lastname: Wang
authors.affiliation: Department of Physiology, Wayne State University School of Medicine , Detroit, Michigan 48201, United States.
authors.forename: Jian-Ping
authors.initials: JP
authors.lastname: Jin
mesh_terms: D000818:Animals; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002478:Cells, Cultured; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008840:Microfilament Proteins / Q000378:metabolism*; D024462:Myosin Type II / Q000378:metabolism*; D000096985:Calponins
chemical_list: D002135:Calcium-Binding Proteins; D008840:Microfilament Proteins; D024462:Myosin Type II; D000096985:Calponins