Gaa, also known as acid alpha-1,4-glucosidase, is a gene encoding an enzyme that catalyzes the hydrolysis of α-1,4 and α-1,6-glucosidic bonds of glycogen. It is involved in the lysosomal breakdown of glycogen, which is crucial for normal cellular function. Mutations in the Gaa gene are associated with Pompe disease, an autosomal recessive disorder [1].

In a mouse model of Pompe disease, the Gaa-/-mouse, Gaa deficiency leads to glycogen accumulation in distal airway cells, disrupting surfactant homeostasis and contributing to respiratory impairments. Histological analysis showed increased accumulation of lysosomal-associated membrane protein 1 in the lungs, ultrastructural examination revealed intracytoplasmic vacuoles enlargement and lamellar body engorgement, and transcriptomic analysis demonstrated dysregulation of surfactant proteins in alveolar type 2 cells [2]. Also, knockdown experiments in zebrafish and human umbilical vein endothelial cells (HUVECs) showed that Gaa deficiency promotes angiogenesis. The mechanism is related to autophagy disorder, which causes up-regulation of Rac1, a small GTPase [3].

In conclusion, Gaa is essential for normal glycogen metabolism. Studies using Gaa-deficient mouse models have revealed its significance in respiratory function and angiogenesis, providing insights into the pathogenesis of Pompe disease. Understanding the role of Gaa in these biological processes may contribute to the development of new treatment strategies for Pompe disease and related conditions.