Molecular characterization of LC3, Beclin-1 and P62 and their response patterns under low temperature and copper ion exposure in Takifugu fasciatus

In recent years, excessive human activities and climate deterioration have led to changes in the aquatic environment, causing frequent diseases in Takifugu fasciatus and huge economic losses. However, it is not clear whether the liver, an important immune organ for fish, can activate autophagy in response to stress caused by environmental changes (e.g., low temperature and Cu2+). Microtubule-associated proteins light chain 3 (lc3), beclin-1 and sequestosome 1 (p62) are important markers of mitochondrial autophagy. In this study, lc3, beclin-1 and p62 were cloned and analyzed for their molecular characteristics, homology and evolutionary relationships with other species using T. fasciatus as the study target. In addition, this experiment also studied the expression and distribution of lc3, beclin-1 and p62 genes in the brain, muscle, intestine, spleen, gill, heart, kidney and liver, and the expression levels in the liver under Cu2+ and a low-temperature environment. Cu2+ and water temperature were able to activate the mRNA and protein expression of lc3, beclin-1 and p62, and beclin-1 was more sensitive than lc3 and p62 in their livers in response to Cu2+ and the low-temperature environment. This study can help to elucidate the molecular mechanism of mitochondrial autophagy genes of T. fasciatus in response to Cu2+ and low-temperature environments, and provide a theoretical basis for guiding the culture of T. fasciatus.