Structural and functional studies of integrin receptors in cultured human keratinocytes.
In human keratinocytes cultured in conditions which allow differentiation and stratification and which are suitable to reconstitute a fully functional epidermis, the integrin alpha 6 beta 4 and two members of the beta 1 integrin family (alpha 2 beta 1 and alpha 3 beta 1) were polarized to the basal and lateral domains of the plasma membrane both in growing colonies and in the reconstituted epidermis. Conversely, alpha v beta 5 integrin was expressed at the basal surface in growing and migrating but not in stationary keratinocytes. The integrin alpha 6 beta 4 was organized in patches and spots corresponding to F-actin-free submembraneous areas and did not colocalize to focal contacts; moreover, alpha 6 beta 4 colocalized with patches of laminin deposited underneath the ventral membrane of individual cells. The two beta 1 laminin receptor integrins (alpha 2 beta 1 and alpha 3 beta 1) were never found in the basal domain but matched the lateral position of vinculin (but not talin), cingulin and desmoplakins. Only the integrin complex alpha v beta 5 was associated with talin- and vinculin-containing focal adhesions mostly in the peripheral cells of expanding keratinocyte colonies and in coincidence with fibronectin strands. The topography of beta 1 and beta 4 integrins reflects a functional role in adhesion and in the maintenance of the state of aggregation of cultured keratinocytes since lateral aggregation was impaired by antibodies to beta 1 whereas antibodies to beta 4 prevented cell-matrix adhesion.
Marchisio
P C
PC
Dipartimento di Scienze Biomediche e Oncologia Umana, Università di Torino, Italy.
Cancedda
R
R
De Luca
M
M
D002118:Calcium / Q000494:pharmacology; D002448:Cell Adhesion; D002449:Cell Aggregation; D002454:Cell Differentiation; D002478:Cells, Cultured; D016326:Extracellular Matrix Proteins / Q000032:analysis*; D005455:Fluorescent Antibody Technique; D006801:Humans; D016023:Integrins / Q000032:analysis* / Q000502:physiology; D015603:Keratinocytes / Q000737:chemistry* / Q000166:cytology; D008565:Membrane Proteins / Q000032:analysis; D011971:Receptors, Immunologic / Q000032:analysis; D017474:Receptors, Laminin
D016326:Extracellular Matrix Proteins; D016023:Integrins; D008565:Membrane Proteins; D011971:Receptors, Immunologic; D017474:Receptors, Laminin; D002118:Calcium