Strategy of Hepatic Metabolic Defects Induced by beclin1 Heterozygosity in Adult Zebrafish

Abstract

Hepatic disorders have been increasing in recent years because of high carbohydrate diets. Hepatocytes depend mainly on the basal autophagy to maintain hepatic glucose/lipid homeostasis in mammals. However, the regulatory mechanisms of autophagy in hepatic energy metabolism are still unknown in fish species. Accordingly, mutant zebrafish lines of autophagy-related genes beclin1 and atg7 were generated by CRISPR/Cas9 gene-editing technology. Interestingly, unlike atg7+/−, male beclin1+/− zebrafish displayed liver defects in the morphology and histology, including abnormal hepatocyte proliferation, hemorrhagic and inflammatory phenotypes. A significant decrease in hepatocyte glycogen and an increase in hepatocyte lipids were detected in the histological assay that coincidence with the hepatic gene expression. Meanwhile, loss of heterozygosity for beclin1 creates a suitable microenvironment for hepatic tumorigenesis via phosphorylation of Akt kinase, which in turn affects liver autophagy. The reduction in autophagy activity in male beclin1+/− liver leads to a disturbance in the glucose/lipid metabolism and negatively regulates apoptosis accompanied by the induction of cellular proliferation and acute inflammatory response. Our findings highlight an important role of beclin1 in zebrafish liver development and energy metabolism, suggesting the crucial role of autophagy in maintaining homeostasis of the nutrient metabolism in fish species.

Zinc Oxide Nanoparticles (ZnO-NPs) Suppress Fertility by Activating Autophagy, Apoptosis, and Oxidative Stress in the Developing Oocytes of Female Zebrafish

“…After centrifugation at 12,000× g round per minute (RPM) for 20 min at 4 °C, the supernatant was collected carefully. The procedure was managed according to previous reports [ 37 ]. After electrophoresis and electrotransfer, Nylon Fluoride (PVDF) membranes (Millipore, Burlington, MA, USA) were cut, blocked against Bovine Serum Albumin (5% BSA, AUG pharma, Giza, Egypt), resolved in Tris Buffered Saline with Tween (TBST) before one hour and then blotted with primary antibodies all night.…”

Antigen Presentation and Autophagy in Teleost Adaptive Immunity

“…Zebrafish mutant lines have shown that becn1 is essential for autophagy, as knock-out mutants for this gene die at the larval stage [100]. In addition, mutants in becn1 and atg7 have outlined the importance of becn1 for maintaining homeostasis of nutrient metabolism and in liver development [101].…”

Exposure of zebrafish to a cold environment triggered cellular autophagy in zebrafish liver

“…Studies in mice with liver‐specific knockout of autophagy found that autophagy is essential for maintaining blood glucose and amino acid levels (Ezaki et al., 2011). In adult zebrafish, impaired autophagy in the liver leads to a disturbance in glucose/lipid metabolism and negatively regulates apoptosis accompanied by the induction of cellular proliferation and an acute inflammatory response (Mawed et al., 2020). However, the regulatory mechanisms of autophagy in hepatic energy metabolism are still obscure in fish species.…”