NSF Award
8819918
Tyrosine hydroxylase (TH) is the enzyme which catalyzes the rate limiting step in the biosynthesis of catecholamines. TH is subject to both short-term and long-term regulation. Regulation of TH is influenced by steroids, growth factors, increased neuronal activity, cold and immolization stress, treatment with protein kinases and drug treatment. The short-term activation of TH (within minutes) involves phosphorylation of the enzyme. Four phosphorylation sites have been localized on the N-terminal regulatory alteration of mRNA levels. This research project will study the mechanism for long-term regulation of TH activity, protein and mRNA levels by treatment with elevated potassium, which depolarizes the neurons and is a model for sustained neuronal activity. A full-length cDNA for this enzyme will be cloned and expressed in a tissue culture cell which does not normally make tyrosine hydroxylase. This will be a first step to begin to change specific phosphorylation sites in the cDNA and determine the activation of the enzyme. The study should lead to valuable information in understanding the molecular basis for the complex regulation of catecholamine biosynthesis.
