Microtubule disruption in keratinocytes induces cell-cell adhesion through activation of endogenous E-cadherin.
The association of the cytoskeleton with the cadherin--catenin complex is essential for strong cell-cell adhesion in epithelial cells. In this study, we have investigated the effect of microtubule organization on cell-cell adhesion in differentiating keratinocytes. When microtubules of normal human epidermal keratinocytes (NHEKs) grown in low calcium media (0.05 mM) were disrupted with nocodazole or colcemid, cell-cell adhesion was induced through relocalization of the E-cadherin-catenin-actin complex to the cell periphery. This was accompanied by actin polymerization. Also, it was found that microtubule disruption-induced cell-cell adhesion was significantly reduced in more advanced differentiated keratinocytes. For example, when NHEK cells cultured under high calcium (1.2 mM) for 8 d and then in low calcium for 1 d were treated with nocodazole, there was no induction of cell-cell adhesion. Also long-term treatment of a phorbol ester for 48 h inhibited nocodazole-induced cell-cell adhesion of NHEK. Furthermore, this nocodazole-induced cell-cell adhesion could be observed in squamous cancer cell lines (A431 and SCC-5, -9, and -25) under low calcium condition, but not in the keratinocyte cell lines derived from normal epidermis (HaCaT, RHEK). On the other hand, HaCaT cells continuously cultivated in low calcium media regained a less differentiated phenotype such as decreased expression of cytokeratin 10, and increased K5; these changes were accompanied with inducibility of cell-cell adhesion by nocodazole. Together, our results suggest that microtubule disruption can induce the cell-cell adhesion via activation of endogenous E-cadherin in non- or early differentiating keratinocytes. However, this is no longer possible in advanced terminally differentiating keratinocytes, possibly due to irreversible changes effected by cell envelope barrier formation.
Kee
S H
SH
Laboratory of Skin Biology, National Institute of Arthritis, Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland 20892-2752, USA.
Steinert
P M
PM
D015820:Cadherins / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000378:metabolism; D000078404:Epidermal Cells; D006801:Humans; D007365:Intercellular Junctions / Q000378:metabolism; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D008870:Microtubules / Q000187:drug effects / Q000502:physiology*; D015739:Nocodazole / Q000494:pharmacology; D014176:Protein Biosynthesis; D011493:Protein Kinase C / Q000378:metabolism; D015534:Trans-Activators; D014407:Tumor Cells, Cultured; D051176:beta Catenin
C495270:CTNNB1 protein, human; D015820:Cadherins; D003598:Cytoskeletal Proteins; D015534:Trans-Activators; D051176:beta Catenin; D011493:Protein Kinase C; D015739:Nocodazole; D002118:Calcium