1,25-Dihydroxyvitamin D production and receptor binding in human keratinocytes varies with differentiation.

S Pillai,D D Bikle,P M Elias

doi:10.1016/s0021-9258(18)60729-x

S Pillai, D D Bikle + Show 1 more

Open Access

https://doi.org/10.1016/s0021-9258(18)60729-x

Copy DOI

Abstract

Human foreskin keratinocytes in culture produce 1,25-dihydroxycholecalciferol (1,25-(OH)2D3) and 24,25-dihydroxycholecalciferol (24,25-(OH)2D3) from 25-hydroxycholecalciferol (25-(OH)D3). The production of 1,25-(OH)2D3 by these cells correlated with the early events of differentiation such as expression of transglutaminase activity and the levels of a precursor protein for the cornified envelopes, involucrin. In contrast, the increased production of 24,25-(OH)2D3, as 1,25-(OH)2D3 production declined, correlated with the terminal differentiation marker, cornified envelope formation. Exogenous 1,25-(OH)2D3 (10(-11)-10(-9) M) inhibited the 1-alpha-hydroxylase at all stages of growth of these cells. Keratinocytes in culture expressed receptors for 1,25-(OH)2D3 which had similar sedimentation behavior in sucrose density gradients as chick intestinal cytosol receptors. Cells in early stages of growth (preconfluent and confluent) contained higher numbers of receptors (26-27 fmol/mg protein) than post-confluent cells. The dissociation constant (237-278 pM) of these receptors for 1,25-(OH)2D3 was not consistently altered by differentiation. Since 1,25-(OH)2D3 is a potent stimulator of cell differentiation in a variety of systems including the epidermis, our results suggest the possibility that endogenous 1,25-(OH)2D3 production may participate in the differentiation of keratinocytes in culture and, perhaps, in vivo.

Highlights

26-hydroxycholecalciferol(26-(OH)D3).Theproduc- (OH)D, [15] in a hormonally regulated fashion [16].As a first tion of l,26-(OH)zD3by thesecells correlatedwith the approach to determining whether endogenous production of early events of differentiation such as expression of 1,25-(OH)*D3could affect differentiation, we investigated transglutaminaseactivity and thelevels of a precursor protein for the cornified envelopes, involucrIin.contrast, the increased production of 24,25-(OH),Ds, as 1,26-(OH)zD3production declined, correlatedwith the terminaldifferentiationmarker,cornifiedenvelope whether basal and hormonally regulated 1,25-(OH)zD3production by these cells was linked to differentiation, and whether the change in hormonal regulation of differentiation could be explained by a change in the 1,25-(OH),D3receptors
Keratinocyte Culture behavior in sucrose density gradients as chick intes- Human keratinocytes were isolated from human newborn foreskins tinal cytosol receptors
Human foreskin keratinocytes maintained in culture differentiate sequentially in a manner analogous to normal epidermis, generating islands of stratifying squamous cells that