Wnt5a Control of Cell Polarity and Directional Movement by Polarized Redistribution of Adhesion Receptors

Abstract

Mechanisms by which Wnt pathways integrate the organization of receptors, organelles, and cytoskeletal proteins to confer cell polarity and directional cell movement are incompletely understood. We show that acute responses to Wnt5a involve recruitment of actin, myosin IIB, Frizzled 3, and melanoma cell adhesion molecule into an intracellular structure in a melanoma cell line. In the presence of a chemokine gradient, this Wnt-mediated receptor-actin-myosin polarity (W-RAMP) structure accumulates asymmetrically at the cell periphery, where it triggers membrane contractility and nuclear movement in the direction of membrane retraction. The process requires endosome trafficking, is associated with multivesicular bodies, and is regulated by Wnt5a through the small guanosine triphosphatases Rab4 and RhoB. Thus, cell-autonomous mechanisms allow Wnt5a to control cell orientation, polarity, and directional movement in response to positional cues from chemokine gradients.Wnt signaling controls cell polarity and directional cell movement in developmental systems, as well as cell invasion in certain cancers. Features shared between noncanonical Wnt pathways include recruitment of Frizzled (Fz) receptors to the posterior end of cells, and asymmetric distribution of atypical cell adhesion molecules, often associated with Fz (1, 2). Thus, receptors redistribute, in response to Wnt, to define an axis of asymmetry. In developmental systems, these processes can be regulated by interactions with adjacent cells, which confer orientation with respect to surrounding tissues (1, 3). For example, during endoderm specification in Caenorhabditis elegans, the division plane in the four-cell blastomere is determined by a positional Wnt signal from a near-by P 2 cell (4). In contrast, Wnt pathway mutations in C. elegans that disrupt neuronal cell migration and polarity can be rescued by Wnt overexpression without requiring a localized source of ligand (5, 6). This suggests that directional presentation of Wnt to cells is not always needed for cell polarization, rather that Wnt ligands act permissively to allow cells to respond to environmental cues for longitudinal guidance and directional movement. In such cases, WM239A cells treated with Wnt5a were immunostained for melanoma cell adhesion molecule (MCAM, also known as MUC18 and CD146), an immunoglobulin G-family cell adhesion receptor implicated in melanoma tumorigenesis and metastasis (9). In untreated cells, MCAM was distributed uniformly. However, treatment of cells with Wnt5a for 30 min led to redistribution of MCAM into a polarized structure, which we call the Wnt5a-mediated receptor-actin-myosin polarity (W-RAMP) structure, for reasons described below (Fig. 1, A and B). The W-RAMP structure was also observed in some untreated cells, but this was suppressed by depleting Wnt5a with RNA interference (RNAi) (Fig. 1B), which indicated that the basal signal results from autocrine responses to endogeneous ligand. Similar W-RAMP structures were observed in WM1789 melanoma cells, as...

Recognition of CD146 as an ERM-binding protein offers novel mechanisms for melanoma cell migration

“…This notion is supported by recent discoveries that upon a gradient of CXCL12 concentrations CD146 could be polarly redistributed to mediate Wnt5a-controlled melanoma cell polarity and directional movement (Witze et al, 2008). A similar CD146-actin-myosin polarity structure was also found asym- CD146 interacts with ERM in cell migration Y Luo et al metrically accumulated in the cell periphery under the treatment of CXCL12 gradient.…”

Sonic Hedgehog Regulates Integrin Activity, Cadherin Contacts, and Cell Polarity to Orchestrate Neural Tube Morphogenesis

“…These observations suggest that Rho GTPases are involved in cytoskeleton stabilization during epithelial morphogenesis (Van Aelst and Symons, 2002). Moreover, Rho GTPases cooperate with Daam1 in the regulation of planar cell polarity (Zallen, 2007) and Daam1 and RhoB have also been implicated in the endocytosis of adhesion receptors and growth factors (Kida et al, 2007;Witze et al, 2008). Upregulation of both genes on Shh misexpression in the dorsal neural tube suggests that reducing matrix adhesion and increasing cell cohesion by SHH signaling also contributes to reinforcement of cell polarity.…”

Wnt5a uses CD146 as a receptor to regulate cell motility and convergent extension

“…Results suggest that in the presence of Wnt5a, the subcellular localization of CD146 is altered. CD146 was accumulated on the cell membrane, in a specific region, thus displaying a polarized enrichment of actin filaments as reported 28 . However, alteration in localization of Ror2, Fz5 or Fz7 was not observed in the presence of Wnt5a (Supplementary Fig.…”

“…The subcellular localization of CD146 was altered in the presence of Wnt5a, which accumulates in the cell membrane, at a specific region that displays a polarized enrichment of actin filaments ( Supplementary Fig. S12) 28 . However, a change in localization in the presence of Wnt5a has not been observed for Ror2, Fz5 or Fz7 (Supplementary Fig.…”