Depletion of E-Cadherin Disrupts Establishment but Not Maintenance of Cell Junctions in Madin-Darby Canine Kidney Epithelial Cells

Capaldo, Christopher; Macara, Ian G.

doi:10.1091/mbc.e06-05-0471

Cited by 233 publications

(232 citation statements)

References 56 publications

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“…Surprisingly, depletion of E-cadherin did not disrupt simple polarity in MDCK cells (7,53). In agreement with this finding, clonal HepG2 cells lacking AJs nonetheless formed intercellular pseudocanaliculi with TJs (i.e., hepatic polarity) in the absence of E-cadherin and ␤-catenin at the cell surface.…”

Section: What Does Simple 3 Hepatic Maturation Require?supporting

confidence: 77%

JAM-A is both essential and inhibitory to development of hepatic polarity in WIF-B cells

Braiterman¹,

Heffernan²,

Nyasae³

et al. 2008

American Journal of Physiology-Gastrointestinal and Liver Physi

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Junctional adhesion molecule (JAM) is involved in tight junction (TJ) formation in epithelial cells. Three JAMs (A, B, and C) are expressed in rat hepatocytes, but only rat JAM-A is present in polarized WIF-B cells, a rat-human hepatic line. We used knockdown (KD) and overexpression in WIF-B cells to determine the role of JAM-A in the development of hepatic polarity. Expression of rat JAM-A short hairpin RNA resulted in ϳ50% KD of JAM-A and substantial loss of hepatic polarity, as measured by the absence of apical cysts formed by adjacent cells and sealed by TJ belts. When inhibitory RNA-resistant human JAM-A (huWT) was expressed in KD cells, hepatic polarity was restored. In contrast, expression of JAM-A that either lacked its PDZ-binding motif (hu⌬C-term) or harbored a point mutation (T273A) did not complement, indicating that multiple sites within JAM-A's cytoplasmic tail are required for the development of hepatic polarity. Overexpression of huWT in normal WIF-B cells unexpectedly blocked WIF-B maturation to the hepatic phenotype, as did expression of three huJAM-A constructs with single point mutations in putative phosphorylation sites. In contrast, hu⌬C-term was without effect, and the T273A mutant only partially blocked maturation. Our results show that JAM-A is essential for the development of polarity in cultured hepatic cells via its possible phosphorylation and recruitment of relevant PDZ proteins and that hepatic polarity is achieved within a narrow range of JAM-A expression levels. Importantly, formation/ maintenance of TJs and the apical domain in hepatic cells are linked, unlike simple epithelia.partitioning-defective polarity protein/atypical protein kinase C complex

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Section: What Does Simple 3 Hepatic Maturation Require?supporting

confidence: 77%

JAM-A is both essential and inhibitory to development of hepatic polarity in WIF-B cells

Braiterman¹,

Heffernan²,

Nyasae³

et al. 2008

American Journal of Physiology-Gastrointestinal and Liver Physi

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“…By removing cadherins in vivo, subsequent to intercellular junction formation, we have uncovered a dependency of TJs on classical cadherins that has not been evident from in vitro studies (24,25). In addition, even though Dms formed, the Dm-keratin IF network appeared no longer able to provide mechanical integrity.…”

Section: Discussionmentioning

confidence: 87%

New insights into cadherin function in epidermal sheet formation and maintenance of tissue integrity

Tinkle

Pasolli

Stokes

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

118

138

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Co-expression and gene linkage have hampered elucidating the physiological relevance of cadherins in mammalian tissues. Here, we combine conditional gene ablation and transgenic RNA interference to uncover new roles for E-and P-cadherins in epidermal sheet formation in vitro and maintenance of epidermal integrity in vivo. By devising skin-specific RNAi technology, we demonstrate that cadherin inhibition in vivo impairs junction formation and intercellular adhesion and increases apoptosis. These defects compromise epidermal barrier function and tissue integrity. In vitro, with only E-cadherin missing, epidermal sheet formation is delayed, but when both cadherins are suppressed, defects extend to adherens junctions, desmosomes, tight junctions and cortical actin dynamics. Using different rescue strategies, we show that cadherin level rather than subtype is critical. Finally, by comparing conditional loss-of-function studies of epidermal catenins and cadherins, we dissect cadherin-dependent and independent roles of adherens junction components in tissue physiology.adherens junctions ͉ epidermis ͉ intercellular adhesion ͉ tissue specific shRNA delivery A dherens junctions (AJs) function in the dynamic regulation of intercellular adhesion (1). The epithelial AJ transmembrane core is composed of E-cadherin (Ecad), whose ectodomain binds Ca 2ϩ to mediate transcadherin interactions between neighboring cells (2, 3). Its intracellular domain binds directly to p120-catenin and ␤-catenin, which in turn binds to ␣-catenin. Together, catenins regulate cadherin stability and coordinate associated actin dynamics to ensure efficient cell adhesion (1, 4).E-cadherin, P-cadherin, ␣-catenin, p120-catenin and ␤-catenin have all been conditionally targeted for ablation in mouse epidermis, making it an excellent system to probe the physiological importance of AJ components (5-11). Given the wellestablished connection between cadherin/catenin mutations and cancers, it was not initially surprising to find that loss of AJ components predisposed skin to cancers. Curiously, however, obvious disruptions of intercellular adhesion are not always among the most striking defects arising from catenin deficiencies in skin (5,6,8,12,13). Thus, although loss of ␣-catenin disrupts epidermal adhesion, the hyperproliferation and inflammation associated with this loss do not rely upon the severing of junctions, but rather on perturbations in Ras-MAPK and NF-B signaling. Moreover, epidermal adhesion is seemingly unaltered when ␤-catenin or p120-catenin is absent, and instead, respective defects in Wnt signaling and inflammation prevail.Ascertaining classical cadherin function(s) in epidermis has been complicated by the up-regulation of P-cadherin (Pcad) in the basal layer when Ecad is absent, the tight linkage of Ecad and Pcad genes, and the presence of cadherin-catenin complexes at cell borders in the other AJ mutant mouse models (10, 11). Using a combined knockout/RNAi strategy, we have now overcome these difficulties and uncovered defects not present ...

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“…Thus, one important consequence of sorting in the RE is the exclusive targeting of E-cadherin to the basolateral membrane to engage epithelial polarity from early stages and to ensure morphogenesis is on track thereafter. Recent studies suggest an essential role for E-cadherin early on in establishing cell polarity (7,30), and one that can be independent of cell-cell adhesion (9). Cells in these situations often retained cell-cell contacts.…”

Section: Discussionmentioning

confidence: 99%

Active Rab11 and functional recycling endosome are required for E-cadherin trafficking and lumen formation during epithelial morphogenesis

Desclozeaux

Venturato²,

Wylie³

et al. 2008

American Journal of Physiology-Cell Physiology

134

141

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herin (E-cadherin) is a major determinant for the acquisition of epithelial cell polarity and for the maintenance of epithelial integrity. The compartments and trafficking components required to sort and transport Ecadherin to the basolateral cell surface remain to be fully defined. On the basis of previous data, we know that E-cadherin is trafficked via the recycling endosome (RE) in nonpolarized and newly polarized cells. Here we explore the role of the RE throughout epithelial morphogenesis in MDCK monolayers and cysts. Time-lapse microscopy in live cells, altering RE function biochemically, and expressing a dominant-negative form of Rab11 (DN-Rab11), each showed that the RE is always requisite for E-cadherin sorting and trafficking. The RE remained important for E-cadherin trafficking in MDCK cells from a nonpolarized state through to fully formed, polarized epithelial monolayers. During the development of epithelial cysts, DN-Rab11 disrupted E-cadherin targeting and trafficking, the subapical localization of pERM and actin, and cyst lumen formation. This final effect demonstrated an early and critical interdependence of Rab11 and the RE for E-cadherin targeting, apical membrane formation, and cell polarity in cysts.

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Depletion of E-Cadherin Disrupts Establishment but Not Maintenance of Cell Junctions in Madin-Darby Canine Kidney Epithelial Cells

Cited by 233 publications

References 56 publications

JAM-A is both essential and inhibitory to development of hepatic polarity in WIF-B cells

JAM-A is both essential and inhibitory to development of hepatic polarity in WIF-B cells

New insights into cadherin function in epidermal sheet formation and maintenance of tissue integrity

Active Rab11 and functional recycling endosome are required for E-cadherin trafficking and lumen formation during epithelial morphogenesis

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