An increase in intracellular free calcium is an early event during differentiation of cultured human keratinocytes

Abstract

The effect of [Ca²⁺]_o on [Ca²⁺]_i in cultured human keratinocytes was studied using dual-wavelength microspectrofluorometric techniques. The results show that increasing [Ca²⁺]_o from 70 μM to 1 mM causes an early rise in [Ca²⁺]_i complete by 2 h. Heterogeneity within cultures was demonstrated.The [Ca²⁺]_i in spontaneously differentiated cells of low Ca²⁺ cultures was similar to that of Ca²⁺ induced differentiated cells. The increase in [Ca²⁺]_i preceded the morphological changes and growth inhibition induced by increasing [Ca²⁺]_o. These observations are consistent with an increase in [Ca²⁺]_i mediating differentiation of human keratinocytes.