Emerging roles of autophagy in hepatic tumorigenesis and therapeutic strategies in glycogen storage disease type Ia: A review

Glycogen storage disease type Ia (GSD-Ia) is an inherited metabolic disease caused by a deficiency in glucose-6-phosphatase-α (G6Pase-α or G6PC) which plays a critical role in blood glucose homeostasis by catalyzing the hydrolysis of glucose-6-phosphate (G6P) to glucose and phosphate in the terminal step of glycogenolysis and gluconeogenesis. Patients with GSD-Ia manifest life-threatening fasting hypoglycemia along with the excessive accumulation of hepatic glycogen and triglycerides which results in hepatomegaly and a risk of long-term complications such as hepatocellular adenoma and carcinoma (HCA/HCC). The etiology of HCA/HCC development in GSD-Ia, however, is unknown. Recent studies have shown that the livers in model animals of GSD-Ia display impairment of autophagy, a cellular recycling process which is critical for energy metabolism and cellular homeostasis. However, molecular mechanisms of autophagy impairment and its involvement in pathogenesis in GSD-Ia are still under investigation. Here, we summarize the latest advances for signaling pathways implicated in hepatic autophagy impairment and the roles of autophagy in hepatic tumorigenesis in GSD-Ia. In addition, recent evidence has illustrated that autophagy plays an important role in hepatic metabolism and liver-directed gene therapy mediated by recombinant adeno-associated virus (rAAV). Therefore, we highlight the possible role of hepatic autophagy in metabolic control and rAAV-mediated gene therapy for GSD-Ia. In this review, we also provide potential therapeutic strategies for GSD-Ia on the basis of molecular mechanisms underlying hepatic autophagy impairment in GSD-Ia.