Altered processing of integrin receptors during keratinocyte activation.
We used monoclonal antibodies against specific integrin subunits to examine the role of integrin receptors in keratinocyte activation. We found that before activation, beta 1 subunits in keratinocytes showed a diffuse distribution, whereas after activation, keratinocytes organized beta 1 receptors into marginal adhesion plaques. In immunoprecipitation experiments with antibodies against beta 1 integrin subunits, we found mostly immature subunits synthesized in keratinocytes freshly harvested from skin. Moreover, integrin receptor complexes immunoprecipitated from these cells by monoclonal antibodies against alpha 2, alpha 3, or alpha 5 subunits contained only immature beta 1 subunits. With keratinocytes cultured 4-7 days, anti-beta 1 antibodies immunoprecipitated mostly mature beta 1 subunits, and integrin complexes immunoprecipitated from cultured cells by anti-alpha subunit antibodies contained mostly mature beta 1 subunits. Antibodies directed against beta 1 subunits also inhibited keratinocyte migration. Based on these results, we suggest that up-regulation of migration by activated keratinocytes depends on changes in processing of pre-beta 1 subunits to mature beta 1 subunits. We also studied the distribution of integrin subunits in skin and on keratinocytes migrating out of skin explants. Whereas beta 1, alpha 2, and alpha 3 subunits were detected in keratinocytes in skin and migrating out of explants, alpha 5 subunits were observed only in migrating cells.
Guo
M
M
Department of Cell Biology and Neuroscience, UT Southwestern Medical Center, Dallas 75235.
Kim
L T
LT
Akiyama
S K
SK
Gralnick
H R
HR
Yamada
K M
KM
Grinnell
F
F
D002454:Cell Differentiation; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D005455:Fluorescent Antibody Technique; D006801:Humans; D016023:Integrins / Q000378:metabolism*; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism*; D011233:Precipitin Tests; D011499:Protein Processing, Post-Translational; D012867:Skin / Q000166:cytology / Q000378:metabolism; D015854:Up-Regulation
D016023:Integrins