Novel regulatory actions of 1α,25-dihydroxyvitamin D3 on the metabolism of polyphosphoinositides in murine epidermal keratinocytes

✍ Scribed by Wilson Tang; Vincent A. Ziboh; R. Rivkah Isseroff; D. Martinez

• Publisher: John Wiley and Sons
• Year: 1987
• Tongue: English
• Weight: 570 KB
• Volume: 132
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.1041320118

✦ Synopsis

The in vitro incubation of murine keratinocytes in the presence of 1a,25dihydroxyvitamin D3 enhanced t h e rapid hydrolysis of the prelabeled keratinocyte polyphosphoinositides (polyPtdlns) when compared to untreated cells. The rapid hydrolysis of the polyPtdlns and the release of the inositol phosphosphates (particularly InsP3 and InsP2) precede the onset of differentiation of these cells. These data therefore suggest that la,25-didydroxyvitamin D3 functions in vitro to initiate the rapid generation of InsP3 from cellular poly-Ptdlns; this in turn may mobilize intracellular Ca2+, thus providing the signal which program the murine keratinocytes from a proliferating mode into a differentiating mode.

MATERIALS AND METHODS

Cell culture conditions

Primary keratinocyte cultures were prepared from mouse epidermis according to the procedure of . Briefly, single cell suspension was obtained through overnight trypsinization of the epidermis at 4°C with 0.25% trypsin in Hank's balanced salt solution. Isolated celIs (6 x 106/60 mm plate) were plated and labeled overnight with 0.4 pCi of my~-[U-~~C]-inosi-to1 (53.3 mCi/mmol, Amersham, Arlington Heights, IL) in Dulbecco's Modified Eagles' Medium (DMEM) (Flow Laboratories, Inglewood, VA) supplemented with 10% fetal calf serum (FCS) (Irvine Scientific, Irvine, CA) at 37°C with 5% C02.