Abstract
Keratinocyte adhesion to basal lamina and lateral interactions among basal epidermal cells are mediated, besides other molecules, by integrin receptors that are sorted to defined membrane domains. The hemidesmosome-associated integrin α 6 β 4 is sharply localized to the basal surface of basal cells while α 2 β 1 and α 3 β 1 are enriched laterally. This integrin sorting pattern is perfectly reproducible in vitro by cultured keratinocytes and takes place progressively in primary or secondary culture in the presence of 1.8 m M Ca 2+. The polarized topography of integrins is gradually lost with higher passage numbers and between passage 5 and passage 7 there is a complete pericellular redistribution of the above integrins. Along with the decreased basal adhesive value of α 6 β 4 there is a marked increase in the number of focal contacts in high-passage keratinocyte colonies. A similar loss of polarized topography of integrins occurs under low-Ca 2+ culture conditions. Increasing the number of culture passages beyond the fifth induces the appearance of the fibronectin receptor α 5 β 1 on the surface of keratinocytes, particularly at intercellular junctions and in some focal contacts. The receptor α 5 β 1 is not detectably exposed by low-passage cells. We propose that forcing keratinocytes into more frequent cell cycles by continuous passaging may perturb the polarized topography of integrins and the adhesion mechanisms of keratinocytes. Then, low-passage keratinocytes are, in our opinion, the most reliable in vitro models for studying the physiology of epidermal cells.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.