Induction of tyrosine hydroxylase and dopamine beta-hydroxylase in cultured mouse neuroblastoma by 8Br-cAMP. Involvement of RNA and protein synthesis

Waymire, J.C.; Gilmer-Waymire, K.; Noritake, D.; Gibson, G.; Kitayama, D.; Haycock, J.W.

Molecular Pharmacology 15(1): 78-85


ISSN/ISBN: 0026-895X
PMID: 34092
Accession: 068518595

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8Br-c) activities in neuroblastoma clone NBD-2 from the mouse C-1300 tumor. The increase in activities was associated with a 5-10 fold increase in the Vmax of both enzymes for both substrate and cofactor. Immunoprecipitation of tyrosine hydroxylase in control and treated cells demonstrated that more immunoprecipitable enzyme was present in the treated samples. Maximal elevation of both tyrosine hydroxylase and dopamine .beta.-hydroxylase occurred after 48 h of treatment with 1.0 mM 8Br-cAMP. Actinomycin D (0.1 .mu.g/ml), cycloheximide (2.0 .mu.g/ml) and lysine-deficient medium prevented the 8Br-cAMP elevation of enzyme activity. Removal of cycloheximide or subsequent addition of lysine (even with simultaneous addition of actinomycin D) allowed the subsequent elevation of enzyme activity. The rate of increase in enzyme activity did not exhibit the lag period typically observed in cells treated only with 8Br-cAMP. cAMP apparently elevates the level of tyrosine hydroxylase and dopamine .beta.-hydroxylase protein. An increased production of mRNA may be 1 of the steps necessary for these effects.