Aquaculture America 2024

February 18 - 21, 2024

San Antonio, Texas

CHAPERONE-MEDIATED AUTOPHAGY REGULATES NUTRIENT METABOLISM, ENERGY BALANCE, AND OXIDATIVE STRESS IN RAINBOW TROUT

Beth Cleveland*, Lisa Radler, Karine Dias, Vincent Veron, Iban Seiliez

 

 USDA National Center for Cool and Cold Water Aquaculture

Kearneysville, WV 25430

Beth.cleveland@usda.gov

 



Chaperone-mediated autophagy (CMA) is a lysosomal-dependent proteolytic pathway recognized in mammals as significant for maintenance of cellular homeostasis during physiological  and metabolic stress . The CMA mechanism has only recently been described as present  in fish, thus its biological function  is not well understood in these species.  The objective of this study was to characterize the  role of CMA as a metabolic regulator in rainbow trout through a loss-of-function approach.  Chaperone-mediated autophagy was disrupted  by CRISPR/Cas9-induced excision of  the 9a exon within the lamp2a gene , thereby inhibiting the  CMA  rate-limiting process of  protein  substrate binding to the lysosomal membrane. Growth and nutrient metabolism and partitioning were characterized in wild type controls and lamp2a knockout (KO) rainbow trout during a high-carbohydrate nutritional challenge.

At 23 weeks post-hatch , KOs exhibited  20% greater body weight than controls ;  this value increased to a 30%  body weight difference  after 7 weeks of consuming a high carbohydrate diet (Fig 1) .  Gene expression analysis in brain suggested an increased appetite contributed to faster growth in KOs (P<0.05). Hepatic lipid profil e was also affected, with increased monounsaturated fatty acids and decreased polyunsaturated fatty acids  in KOs relative to controls (P<0.01). Elevated expression of genes associated with lipid metabolism (P<0.05) suggesting an increased capacity for lipid synthesis in KOs .  Hepatic proteome analysis  indicated lamp2a KO affected  the  abundance of  proteins linked with glucose, lipid, and glutathione metabolism, as well as mitochondrial respiration and proteasome activity (Fig 2,3).

 Findings indicate that CMA  is a central mechanism regulating growth , metabolism,  energy production,  and oxidative stress in rainbow trout.  Further characterizing how CMA responds to metabolic, environmental, and  immunological stressors will reveal how fish regulate cellular homeosta sis under metabolic stress and contribute to development of strategies that improve production efficiency.