Beta ig-h3 induces keratinocyte differentiation via modulation of involucrin and transglutaminase expression through the integrin alpha3beta1 and the phosphatidylinositol 3-kinase/Akt signaling pathway.
Beta ig-h3 is an extracellular matrix protein whose expression is highly induced by transforming growth factor (TGF)-beta1. Whereas beta ig-h3 is known to mediate keratinocyte adhesion and migration, its effects on keratinocyte differentiation remain unclear. In the present study, it was demonstrated that expression of both beta ig-h3 and TGF-beta1 was enhanced during keratinocyte differentiation and that expression of the former was strongly induced by that of the latter. This study also asked whether changes in beta-h3 expression would affect keratinocyte differentiation. Indeed, down-regulation of beta ig-h3 by transfection with antisense beta ig-h3 cDNA constructs effectively inhibited keratinocyte differentiation by decreasing the promoter activities and thus expression of involucrin and transglutaminase. The result was an approximately 2-fold increase in mitotic capacity of the cells. Conversely, overexpression of beta ig-h3, either by transfection with beta ig-h3 expression plasmids or by exposure to recombinant beta ig-h3, enhanced keratinocyte differentiation by inhibiting cell proliferation and concomitantly increasing involucrin and transglutaminase expression. Recombinant beta ig-h3 also promoted keratinocyte adhesion through interaction with integrin alpha3beta1. Changes in beta ig-h3 expression did not affect intracellular calcium levels. Subsequent analysis revealed not only induction of Akt phosphorylation by recombinant beta ig-h3 but also blockage of Akt phosphorylation by LY294002, an inhibitor of phosphatidylinositol 3-kinase. Taken together, these findings indicate that enhanced beta ig-h3, induced by enhanced TGF-beta during keratinocyte differentiation, provoked cell differentiation by enhancing involucrin and transglutaminase expression through the integrin alpha3beta1 and phosphatidylinositol 3-kinase/Akt signaling pathway. Lastly, it was observed that beta ig-h3-mediated keratinocyte differentiation was caused by promotion of cell adhesion and not by calcium regulation.
Oh
Ju-Eun
JE
Department of Oral Biochemistry and Craniomaxillofacial Reconstructive Sciences, Dental Research Institute, and BK21 HLS, Seoul National University College of Dentistry, Seoul 110-749, Korea.
Kook
Joong-Ki
JK
Min
Byung-Moo
BM
D000328:Adult; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D002448:Cell Adhesion; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D018076:DNA, Complementary / Q000378:metabolism; D015536:Down-Regulation; D016326:Extracellular Matrix Proteins / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D039201:Integrin alpha3beta1 / Q000378:metabolism*; D015603:Keratinocytes / Q000166:cytology* / Q000378:metabolism; D008858:Microscopy, Phase-Contrast; D008938:Mitosis; D008954:Models, Biological; D009025:Morpholines / Q000494:pharmacology; D016376:Oligonucleotides, Antisense / Q000737:chemistry; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011498:Protein Precursors / Q000096:biosynthesis*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000378:metabolism / Q000502:physiology*; D011503:Transglutaminases / Q000096:biosynthesis*; D000099222:betaIG-H3 Protein
D002118:Calcium; D002867:Chromones; D018076:DNA, Complementary; D016326:Extracellular Matrix Proteins; D039201:Integrin alpha3beta1; D009025:Morpholines; D016376:Oligonucleotides, Antisense; D019869:Phosphatidylinositol 3-Kinases; D011498:Protein Precursors; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; D011503:Transglutaminases; D000099222:betaIG-H3 Protein; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C032253:involucrin