Structural and functional characterization of AMPK-α subunit in Litopenaeus vannamei: A function modulator of lipid metabolism, oxidative stress, and immune response

Environmental stressors can induce oxidative stress and lead to oxidative damage in Litopenaeus vannamei . Under oxidative stress, the antioxidant system of shrimp is activated to resist oxidative stress and alleviate oxidative damage. Oxidative stress can also lead to energy metabolism disorders in shrimp. Maintaining energy metabolism homeostasis plays a vital role in defending against oxidative stress. AMP-activated protein kinase (AMPK) is a pivotal regulator of cellular energy homeostasis. AMPK-α is a subunit which plays a crucial role as the catalytic core in the AMPK complex. Here, the role of AMPK-α on high-fat feeding, oxidative stress and immunity of Litopenaeus vannamei were studied. Through a comparative analysis of conserved structural regions, it was found that AMPK-α was highly conserved in crustaceans and teleost fish. AMPK-α was expressed in all tissues of L. vannamei , especially in the hepatopancreas, epidermis and gill. A high fat diet could induce a significant increase in AMPK-α expression in the hepatopancreas and muscle. Ammonia nitrogen exposure, poly (I:C) and V. harveyi stimulation could also lead to AMPK-α changes in the hepatopancreas, gill and intestine in a time-dependent manner. Knockdown of AMPK-α downregulated energy metabolism-related genes ( GLUT1 , CS , mTOR , ATPΣ , COII , and PFKFB2 ), antioxidant-related genes ( Nrf2, NQO1 , and SOD ) and autophagy-related gene ( p62 ), while upregulating mTOR in the hepatopancreas, gill and intestine. Furthermore, compared to stimulation with V. harveyi in L. vannamei alone, stimulation with V. harveyi after knockdown of AMPK-α downregulated energy metabolism-, antioxidant-, and autophagy-related genes in L. vannamei . Meanwhile, knockdown of AMPK-α could induce vacuolization of the hepatopancreatic tubules and apoptosis of hepatopancreatic cells, and aggravate hepatopancreatic injury induced by V. harveyi , such as obvious thinning of tubule walls and vacuolation. These results indicate that AMPK-α is involved in energy metabolism, oxidative stress and the immune response of L. vannamei , which further demonstrates the important role of AMPK-α in shrimp. • AMPK-α expression is strongly induced by a high-fat diet, ammonia nitrogen exposure, poly (I:C) and Vibrio harveyi. • AMPK-α knockdown suppresses key functional genes and triggers hepatopancreatic damage and apoptosis. • Knockdown of AMPK-α aggravated the damage and apoptosis of the hepatopancreas of L . vannamei infected with Vibrio harveyi.