Junctional recruitment of mammalian Scribble relies on E-cadherin engagement

Abstract

Members of the LAP protein family, LET-413 inCaenorhabditis elegans, Scribble in Drosophila melanogaster, and Erbin, Lano, Densin-180 and hScrib in mammals, have conserved structural features. LET-413 and Scribble are junctional proteins involved in establishing and maintaining epithelial cell polarity. scribble also behaves as a neoplastic tumor suppressor gene. We show here that, in epithelial cells, hScrib is recruited at cell-cell junctions in an E-cadherin-dependent manner as shown by calcium switch assays in MDCK cells, re-expression of E-cadherin in MDA-231 cells treated by 5-Aza-2 0 -deoxycytidine (5Aza), and siRNA experiments. hScrib is restricted at the basolateral membrane of epithelial cells by its LRR domain, and is enriched in Triton X-100-insoluble fractions. In breast cancers, most lobular tumors did not express hScrib and E-cadherin while ductal tumors had a less frequent downregulation of hScrib. Our data provide additional insights on the modalities of recruitment of hScrib at the cell-cell junctions, and establish a potential link between the E-cadherin and hScrib tumor suppressors.

The tumour-suppressor Scribble dictates cell polarity during directed epithelial migration: regulation of Rho GTPase recruitment to the leading edge

“…Under these culture conditions Scribble KD cells formed spherical clonal acini that were morphologically indistinguishable from parental and cells expressing a control hairpin targeting EGFP (shEGFP) control acini ( Figure 1c). As reported for Madin-Darby canine kidney (MDCK) epithelial cells (Dow et al, 2003;Navarro et al, 2005), Scribble was localized to points of cell-cell contact in MCF10A DNA hScrib…”

“…Studies in a number of different human cancers have now shown that loss of Scribble and Dlg is associated with more invasive and aggressive malignancies (Watson et al, 2002;Boussioutas et al, 2003;Cavatorta et al, 2004;Lin et al, 2004;Nakagawa et al, 2004;Navarro et al, 2005;Gardiol et al, 2006). It is now clear that Scribble plays a critical role in the regulation of directed cell migration during development and tissue homeostasis (e.g.…”

“…While in this context Scribble serves to negatively regulate cell motility and invasion, during Drosophila development Scribble is required to positively regulate the migration of epithelial sheets during dorsal closure of the embryo (Bilder et al, 2003), implying the role of Scribble in controlling cell movement may be cell type and/or context dependent. The single human homologue of Scribble is highly concentrated at epithelial cell junctions and expression of Scribble can rescue the polarity and overgrowth defects of Drosophila scribble mutants suggesting that Scribble may function as a tumour suppressor and regulate polarity in mammalian cells (Dow et al, 2003;Navarro et al, 2005). The recent identification and analysis of mouse Scribble (scrb1) as the gene mutated in the mouse circletail (Crc) (Murdoch et al, 2003) and rumpelstilzchen (rumz) (Zarbalis et al, 2004) mutants have indicated an important role for Scribble in mammalian development and planar cell polarity, however, the neonatal lethality of these mutants has so far precluded detailed analysis of Scribble function in epithelia.…”

Asymmetric Localization of Vangl2 and Fz3 Indicate Novel Mechanisms for Planar Cell Polarity in Mammals

“…In addition, the protein was localized along the basolateral membranes of HCs and SCs (Fig. 4 B), as reported previously (Navarro et al, 2005). In MDCK cells, endogenous Scrb1 is strongly expressed at the cell membranes, in which Vangl2 is targeted when overexpressed (Navarro et al, 2005;Qin et al, 2005).…”

Aberrant Overexpression of the Cell Polarity Module Scribble in Human Cancer

“…2 Experimental evidence, first collected in Drosophila melanogaster 3 and later extended to mammalian cells, 4 implicates Scrib as a general regulator of directional cell motility, largely via the assembly of multiprotein complexes and the activation of small GTPase signaling at the leading edge of migrating cells. 5,6 Accordingly, loss-of-function Scrib mutants 7 or depletion of Scrib 4 has disrupted apical-basal polarity 8 and has cooperated with oncogenic signals 9 to enhance tumor cell migration, invasion, and survival.…”