The terminal differentiation of epithelial keratinocytes has been proposed to be a specialized form of programmed cell death (apoptosis). We examined the time correlation of apoptosis and terminal differentiation by human ectocervical keratinocytes in a suspension culture that induces either of these events in epithelial cells. We found that a loss of cell anchorage did not result in the immedi...

The skin is susceptible to different injuries and diseases. One major obstacle in skin tissue engineering is how to develop functional three-dimensional (3D) substitute for damaged skin. Previous studies have proved a 3D dynamic simulated microgravity (SMG) culture system as a "stimulatory" environment for the proliferation and differentiation of stem cells. Here, we employed the NASA-approved ...

Rap1 is a small GTP-binding protein (SMG) that exists in two 95% homologous isoforms, rap1A and rap1B. The functions of the rap1 proteins are not well understood. In this report we examined expression and function of rap1 in primary (HOKs) and immortalized (IHOKs) human oral keratinocytes under different growth conditions. In HOKs, rap1 increased with passage number, suggesting a role in differ...

Human epidermal keratinocytes, immortalized by the intToduction of SV40-adenovirus recombinants {9). were maintained in a low calcium <e.I5 mM) defined medium. When differentiation was induced by a higher extracellular calcium concentration {I.5 mM), these cells altered in shape and developed stratification with forrnation of desmosornes, while they demons(rated limited terminal keratinization....

The evolution of the anthropoid involucrin gene has resulted largely from a process of vectorial addition of short tandem repeats. The coding region of the involucrin gene of the gibbon (Hylobates lar), including the segment of repeats, has been cloned and sequenced, and its repeat structure can now be compared with that of the other hominoids. In the gibbon, as in the others, repeat additions ...

In the evolutionary line leading to the higher primates, the coding region of the involucrin gene evolved a segment consisting of numerous repeats of a 10-codon sequence. Additions to this segment of repeats have been made successively, thus generating regions that can be defined as early, middle, and late. The involucrin gene of the orangutan (Pongo pygmaeus abelii) possesses a segment of repe...

Materials and methods: Gingival epithelial cells were seeded and cultured at 10−3 G in a three-dimensional clinostat to simulate microgravity (group CL) or in normal gravity (group C) for 10 days. Cell proliferation was analyzed by counting the numbers of cells. Real-time polymerase chain reaction was performed to amplify the krt 5, krt 13 and involucrin genes. Additionally, total protein was i...

Cultures of human epidermal keratinocytes provide a useful experimental model with which to study the factors that regulate cell proliferation and terminal differentiation. One situation that is known to trigger premature terminal differentiation is suspension culture, when keratinocytes are deprived of substratum and intercellular contact. We have now investigated whether area of substratum co...