title: Dissecting the roles of ROCK isoforms in stress-induced cell detachment.
abstract: The homologous Rho kinases, ROCK1 and ROCK2, are involved in stress fiber assembly and cell adhesion and are assumed to be functionally redundant. Using mouse embryonic fibroblasts (MEFs) derived from ROCK1(-/-) and ROCK2(-/-) mice, we have recently reported that they play different roles in regulating doxorubicin-induced stress fiber disassembly and cell detachment: ROCK1 is involved in destabilizing the actin cytoskeleton and cell detachment, whereas ROCK2 is required for stabilizing the actin cytoskeleton and cell adhesion. Here, we present additional insights into the roles of ROCK1 and ROCK2 in regulating stress-induced impairment of cell-matrix and cell-cell adhesion. In response to doxorubicin, ROCK1(-/-) MEFs showed significant preservation of both focal adhesions and adherens junctions, while ROCK2(-/-) MEFs exhibited impaired focal adhesions but preserved adherens junctions compared with the wild-type MEFs. Additionally, inhibition of focal adhesion or adherens junction formations by chemical inhibitors abolished the anti-detachment effects of ROCK1 deletion. Finally, ROCK1(-/-) MEFs, but not ROCK2(-/-) MEFs, also exhibited preserved central stress fibers and reduced cell detachment in response to serum starvation. These results add new insights into a novel mechanism underlying the anti-detachment effects of ROCK1 deletion mediated by reduced peripheral actomyosin contraction and increased actin stabilization to promote cell-cell and cell-matrix adhesion. Our studies further support the differential roles of ROCK isoforms in regulating stress-induced loss of central stress fibers and focal adhesions as well as cell detachment.
authors.affiliation: Riley Heart Research Center, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: Jianjian
authors.initials: J
authors.lastname: Shi
authors.forename: Michelle
authors.initials: M
authors.lastname: Surma
authors.forename: Lumin
authors.initials: L
authors.lastname: Zhang
authors.forename: Lei
authors.initials: L
authors.lastname: Wei
mesh_terms: D008841:Actin Cytoskeleton / Q000187:drug effects; D022005:Adherens Junctions / Q000187:drug effects; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D051338:Cofilin 1 / Q000378:metabolism; D004317:Doxorubicin / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D022001:Focal Adhesions / Q000187:drug effects; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D010766:Phosphorylation; D022502:Stress Fibers / Q000187:drug effects; D054460:rho-Associated Kinases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*
chemical_list: D000903:Antibiotics, Antineoplastic; D051338:Cofilin 1; D008565:Membrane Proteins; C498927:Mlc1 protein, mouse; D004533:Egtazic Acid; D004317:Doxorubicin; C515854:Rock1 protein, mouse; C515855:Rock2 protein, mouse; D054460:rho-Associated Kinases
keywords: Rho kinase; actin cytoskeleton; cell-matrix and cell-cell adhesion; detachment; doxorubicin; isoform; serum starvation; stress fibers