Decreased expression of alpha3 and beta1 integrin subunits is responsible for differentiation-associated changes in cells behavior in terminally differentiated human oral keratinocytes.
Primary normal human oral keratinocytes (NHOKs) terminally differentiate in serial subculture. To investigate whether this subculture-induced differentiation of NHOKs affects integrin expression and cell-matrix interaction, we studied the expression levels of integrin subunits and cellular response to the extracellular matrix (ECM) proteins in NHOKs at different population doublings. The phosphorylation statuses of focal adhesion kinase (FAK), extracellular signal regulated kinase (ERK), p38, and c-Jun amino-terminal kinase (JNK) were also determined in NHOK cells cultured on ECM proteins, to evaluate the functions of integrins with respect to cellular responses to ECM proteins. The expression levels of alpha3 and beta1 integrin subunits progressively decreased in NHOKs undergoing terminal differentiation. The ability of NHOKs to spread upon laminin and type I collagen significantly decreased in terminally differentiated oral keratinocytes. Keratinocyte migration was significantly increased on type I collagen for terminally differentiated NHOKs. Similar results were seen following preincubation of rapidly proliferating NHOKs with function-blocking antibodies to alpha3 or beta1 integrin subunit. In contrast, fibronectin had no effect on cellular responses in NHOKs, which were almost negligible in the expression levels of alpha5 integrin subunits. The extent of FAK phosphorylation in terminally differentiated NHOKs was notably lower than that of rapidly proliferating cells, but was enhanced in terminally differentiated cells that were cultured on type I collagen. Our results indicate that decreased expression of alpha3 and beta1 integrin subunits is responsible for differentiation-associated changes in cells behavior in terminally differentiated oral keratinocytes. Our data also show that the abrogation of the alpha5beta1 integrin function caused by omitting alpha5 subunit is linked to the loss of a cell-fibronectin interaction in human oral keratinocytes.
Oh
Ju-Eun
JE
Departments of Oral Biochemistry, Dental Research Institute, IBEC, College of Dentistry, Seoul National University, Seoul, Korea.
Park
Kyung-Hee
KH
Noh
Hyung Kil
HK
Kim
Jin-Man
JM
Chung
Chong-Pyoung
CP
Min
Byung-Moo
BM
D000911:Antibodies, Monoclonal; D002448:Cell Adhesion / Q000502:physiology; D002454:Cell Differentiation / Q000502:physiology*; D002465:Cell Movement / Q000502:physiology*; D002478:Cells, Cultured; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis; D005434:Flow Cytometry; D006801:Humans; D039422:Integrin alpha3 / Q000096:biosynthesis*; D019012:Integrin beta1 / Q000096:biosynthesis*; D039661:Integrin beta3 / Q000096:biosynthesis; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009061:Mouth Mucosa / Q000166:cytology / Q000378:metabolism; D010766:Phosphorylation; D010770:Phosphotransferases / Q000378:metabolism
D000911:Antibodies, Monoclonal; D016326:Extracellular Matrix Proteins; D039422:Integrin alpha3; D019012:Integrin beta1; D039661:Integrin beta3; D010770:Phosphotransferases; D020928:Mitogen-Activated Protein Kinases