1,25-dihydroxyvitamin D3 stimulates the assembly of adherens junctions in keratinocytes: involvement of protein kinase C.
Signaling via intercellular junctions plays an important role in the regulation of growth and differentiation of epithelial cells. Loss of cell-cell contacts has been implicated in carcinogenesis, tumor progression, and metastasis. Here, we investigated whether 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] was able to stimulate the assembly of adherens junctions and/or desmosomes in cultured human keratinocytes. After 4-day incubation, 1,25-(OH)2D3 caused assembly of adherens junctions, but not desmosomes. The adherens junctions were identified upon known ultrastructural criteria and evidence of the translocation of specific junctional proteins (E-cadherin, P-cadherin, alpha-catenin, and vinculin) to the cell-cell borders. The presence of alpha-catenin and vinculin at cell-cell borders indicated that the adherens junctions were functional. This was further supported by showing that anti E-cadherin antibody inhibited the 1,25-(OH)2D3-induced keratinocyte stratification. A relation between protein kinase C and adherens junction regulation was noticed. 1,25-(OH)2D3-dependent formation of junctions was blocked by the inhibitors of protein kinase C, bisindolylmaleimide and 1-(5-isoquinolinylsulfonyl)-2-methyl-piperazine (H-7), and treatment of keratinocytes with 1,25-(OH)2D3 caused a rapid activation of protein kinase C and its translocation to the membranes. Formation of intercellular contacts may be an important mechanism of 1,25-(OH)2D3 action in hyperproliferative and neoplastic diseases.
Gniadecki
R
R
Department of Dermatological Research, Leo Pharmaceutical Products, Ballerup, Denmark.
Gajkowska
B
B
Hansen
M
M
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000494:pharmacology; D000704:Analysis of Variance; D015820:Cadherins / Q000502:physiology; D002117:Calcitriol / Q000494:pharmacology*; D002448:Cell Adhesion; D002462:Cell Membrane / Q000201:enzymology; D002478:Cells, Cultured; D015925:Cryopreservation; D003600:Cytosol / Q000201:enzymology; D003896:Desmosomes / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D006801:Humans; D007231:Infant, Newborn; D007365:Intercellular Junctions / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D008854:Microscopy, Electron; D011493:Protein Kinase C / Q000378:metabolism*
D015820:Cadherins; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D011493:Protein Kinase C; D002117:Calcitriol