Effect of cAMP-dependent Phosphodiesterase Activity on NTH1 Gene Expression and Reserve Carbohydrate Metabolism

Abstract

Protein kinase A signaling pathway is regulated by cAMP. PKA activity is inhibited by the cAMP phosphodiesterases. PDE1 and PDE2 genes encode two phosphodiesterases with low and high affinity for cAMP, respectively. NTH1 gene encodes the neutral trehalase enzyme, which is responsible for the stress-accumulated trehalose degradation. This study aimed to investigate the effect of PDE1 and PDE2 gene products on the expression of the NTH1 gene and reserve carbohydrate metabolism in response to a stressful environment and during a replenishment phase. The expression of the NTH1 gene was shown to be lower than that of the wild-type under normal conditions, heat stress, nitrogen starvation, and also during the replenishment period in pde1∆ and pde1∆ yeast cells. The accumulation of trehalose and glycogen was shown to be dramatically enhanced in pde1∆ yeast cells. However, deletion of the PDE2 gene did not lead to a significant change in trehalose and glycogen accumulation comparable to that found in the wild type. These results indicate that the PDE1 gene product is required for downregulation of reserve carbohydrate metabolism. Consequently, the Pde1 protein is considered to exert yet-unidentified regulatory control over the Pde2 protein.