Adenylate cyclases in keratinocytes: FRSK cells express types I, II, III, IV, VI and VIII, and 1,25(OH)2D3, retinoic acid and TPA augment forskolin-induced cyclic AMP accumulation in the absence of altered isozyme expression.

Molecular cloning analysis has detected at least nine adenylate cyclase isozymes in mammalian tissues. Using fetal rat skin keratinocytes (FRSK), we investigated adenylate cyclase expression and its modulation by 1,25-dihydroxyvitamin D 3 (1,25(OH) 2 D 3 ), a retinoid (Ro10-1670), and 12-O-tetradecanoylphorbol-13-acetate (TPA). Reverse transcription polymerase chain reaction (RT-PCR) indicated that FRSK contain adenylate cyclases I, II, III, IV, VI and VIII. Treatment with 1,25(OH) 2 D 3 (1 x 10 -7 M), Ro10-1670 (1 x 10 -6 M), and TPA (100 ng/ml) resulted in increased forskolin-induced cyclic AMP accumulation by FRSK cells and normal human keratinocytes (NHK). Quantitative RT-PCR and Western blot analysis, however, detected no alteration in mRNA and protein levels of each adenylate cyclase isozyme for at least 48 h. These results indicate that FRSK contain at least six (I, II, III, IV, VI and VIII) adenylate cyclase isozyme mRNAs, suggesting a complex regulatory mechanism of cyclic AMP generation in keratinocytes. Although 1,25(OH) 2 D 3 , Ro10-1670, and TPA augmented forskolin-induced cyclic AMP accumulation, they do not seem to affect the expression of specific adenylate cyclase isozymes by FRSK cells.