Myosin 2 Is a Key Rho Kinase Target Necessary for the Local Concentration of E-Cadherin at Cell–Cell Contacts

Abstract

Classical cadherins accumulate at cell-cell contacts as a characteristic response to productive adhesive ligation. Such local accumulation of cadherins is a developmentally regulated process that supports cell adhesiveness and cell-cell cohesion. Yet the molecular effectors responsible for cadherin accumulation remain incompletely understood. We now report that Myosin 2 is critical for cells to concentrate E-cadherin at cell-cell contacts. Myosin 2 is found at cadherin-based cell-cell contacts and its recruitment requires E-cadherin activity. Indeed, both Myosin 2 recruitment and its activation were stimulated by E-cadherin homophilic ligation alone. Inhibition of Myosin 2 activity by blebbistatin or ML-7 rapidly impaired the ability of cells to concentrate E-cadherin at adhesive contacts, accompanied by decreased cadherin-based cell adhesiveness. The total surface expression of cadherins was unaffected, suggesting that Myosin 2 principally regulates the regional distribution of cadherins at the cell surface. The recruitment of Myosin 2 to cadherin contacts, and its activation, required Rho kinase; furthermore, inhibition of Rho kinase signaling effectively phenocopied the effects of Myosin 2 inhibition. We propose that Myosin 2 is a key effector of Rho-Rho kinase signaling that regulates cell-cell adhesion by determining the ability of cells to concentrate cadherins at contacts in response to homophilic ligation.

ZO-1- and ZO-2-Dependent Integration of Myosin-2 to Epithelial Zonula Adherens

“…As a result, we found that Y27632 dissociated myosin-2 from the ZA, consistent with a previous report on MCF7 cells (Shewan et al, 2005). Phosphorylation of myosin-2 is reportedly a downstream event in the ROCK pathway.…”

Coronin 1B supports RhoA signaling at cell-cell junctions through Myosin II

“…20 We then examined the localization of non-muscle myosin II in MCF-7 cells depleted of Coronin 1B, as E-cadherin and F-actin have been shown to influence the recruitment of non-muscle myosin II to junctions. 4,6,19 As previously described, 4,6,19 NMIIA and NMIIB concentrated prominently at the zonulae adherente of control MCF-7 monolayers (Fig. 1D, E).…”

“…Since NMIIA was more stable at the ZA than in other regions of cell-cell junctions, this defined where the junctional RhoA zone was established. 7 In addition to activation by RhoA-ROCK signaling 2,19 , the junctional localization of NMIIA can also be influenced by the F-actin networks with which it associates. 20,21 Actin regulators comprise actin polymerization factors as well as regulators of F-actin architecture.…”

Loss of Cell Adhesion Causes Hydrocephalus in Nonmuscle Myosin II-B–ablated and Mutated Mice

“…Nonmuscle myosin (NM) II, one of the major cytoskeletal motor proteins, plays an important role in cell migration (Svitkina et al, 1997;Ma et al, 2004;Even-Ram et al, 2007;Vicente-Manzanares et al, 2007), cell-cell adhesion Shewan et al, 2005;Giannone et al, 2007), and cell division (De Lozanne and Spudich, 1987;Takeda et al, 2003;Bao et al, 2005). The molecular structure of NM II is a hexamer consisting of a pair of myosin heavy chains (200 kDa) and two pairs of light chains (20 and 17 kDa).…”

“…The defect may be accompanied by an obstructed aqueduct of Sylvius, the narrow channel connecting the third and fourth brain ventricles (noncommunicating hydrocephalus), or by a normal aqueduct (communicating hydrocephalus). The pathogenesis of most cases of communicating hydrocephalus is largely unknown (for reviews, see Perez-Figares et al, 2001;Crews et al, 2004).Nonmuscle myosin (NM) II, one of the major cytoskeletal motor proteins, plays an important role in cell migration (Svitkina et al, 1997;Ma et al, 2004;Even-Ram et al, 2007;Vicente-Manzanares et al, 2007), cell-cell adhesion Shewan et al, 2005;Giannone et al, 2007), and cell division (De Lozanne and Spudich, 1987;Takeda et al, 2003;Bao et al, 2005). The molecular structure of NM II is a hexamer consisting of a pair of myosin heavy chains (200 kDa) and two pairs of light chains (20 and 17 kDa).…”