Transcriptional and post-transcriptional regulation of tyrosine hydroxylase gene by protein kinase C.
The role played by protein kinase C (PKC) in TH gene regulation was investigated at transcriptional and post-transcriptional levels using PC12 cells. The cells were treated with the phorbol ester TPA, which not only activates PKC but also causes down-regulation. PKC levels were monitored by [3H]PDBU binding assay and by using an anti-PKC antibody that detected intact PKC (79 kd) as well as its catalytic and regulatory domains. The [3H]PDBU binding to the membrane-associated PKC increased within 15-30 min of TPA treatment; thereafter total cellular [3H]PDBU binding decreased to a minimum of 20% of the control at 8 h. The rate of decrease in binding was greater than the decrease in the intensity of the staining of PKC holo enzyme visualized by anti-PKC antibody. TH mRNA levels, measured over the same time period, rose within 15 min of TPA treatment to peak at 4 h and subsequently declined below control level, paralleling the depletion of PKC. If cells depleted of PKC were reincubated in the normal medium, a recovery in PKC level was seen and, in parallel, TH mRNA levels increased to above control level. Furthermore, if down-regulation of PKC was prevented by incubating the cells with the protease inhibitor leupeptin, a decrease beyond control level in TH mRNA was not observed. TPA rapidly induced TH gene transcription; a maximal increase of two-fold was observed at 15 min, but the transcriptional rate then declined although it did not decrease beyond control values after 8 and 24 h of TPA treatment.(ABSTRACT TRUNCATED AT 250 WORDS)
Vyas
S
S
Laboratoire de Neurobiologie Cellulaire et Moleculaire, Centre National de la Recherche Scientifique Gif/Yvette, France.
Faucon Biguet
N
N
Mallet
J
J
D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D015152:Blotting, Northern; D002460:Cell Line; D003609:Dactinomycin / Q000494:pharmacology; D015870:Gene Expression; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D011493:Protein Kinase C / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014158:Transcription, Genetic; D014446:Tyrosine 3-Monooxygenase / Q000235:genetics*
D000470:Alkaloids; D012333:RNA, Messenger; D003609:Dactinomycin; D014446:Tyrosine 3-Monooxygenase; D011493:Protein Kinase C; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate