Proteasomal proteolysis in the adrenergic induction of arylalkylamine-N-acetyltransferase in rat pinealocytes.

In this study, we investigated the effect of proteasomal inhibition on the induction of arylalkylamine-N-acetyltransferase (AA-NAT) enzyme in cultured rat pinealocytes, using two proteasome inhibitors, MG132 and clastolactacystin beta-lactone (c-lact). Addition of c-lact or MG132 3 h after norepinephrine (NE) stimulation produced a significant increase in AA-NAT protein level and enzyme activity. However, when the proteasome inhibitors were added before or together with NE, significant reductions of the NE-induced aa-nat mRNA, protein, and enzyme activity were observed.