Abstract
The autophagy-lysosome pathway, which involves many crucial genes and proteins, plays crucial roles in the maintenance of intracellular homeostasis by the degradation of damaged components. At present, some of these genes and proteins have been identified but their specific functions are largely unknown. This study was performed to clone and characterize the full-length cDNA sequences of nine key autolysosome-related genes (vps11, vps16, vps18, vps33b, vps41, lamp1, mcoln1, ctsd1 and tfeb) from yellow catfish Pelteobagrus fulvidraco. The expression of these genes and the transcriptional responses to a high-fat diet and fatty acids (FAs) (palmitic acid (PA) and oleic acid (OA)) were investigated. The mRNAs of these genes could be detected in heart, liver, muscle, spleen, brain, mesenteric adipose tissue, intestine, kidney and ovary, but varied with the tissues. In the liver, the mRNA levels of the nine autolysosome-related genes were lower in fish fed a high-fat diet than those fed the control, indicating that a high-fat diet inhibited formation of autolysosomes. Palmitic acid (a saturated FA) significantly inhibited the formation of autolysosomes at 12 h, 24 h and 48 h incubation. In contrast, oleic acid (an unsaturated FA) significantly induced the formation of autolysosomes at 12 h, but inhibited them at 24 h. At 48 h, the effects of OA incubation on autolysosomes were OA concentration-dependent in primary hepatocytes of P. fulvidraco. The results of flow cytometry and laser confocal observations confirmed these results. PA and OA incubation also increased intracellular non-esterified fatty acid (NEFA) concentration at 12 h, 24 h and 48 h, and influenced mRNA levels of fatty acid binding protein (fabp) and fatty acid transport protein 4 (fatp4) which facilitate FA transport in primary hepatocytes of P. fulvidraco. The present study demonstrated the molecular characterization of the nine autolysosome-related genes and their transcriptional responses to fat and FAs in fish, which provides the basis for further exploring their regulatory mechanism in vertebrates.
Highlights
Autophagy is significantly conserved during evolution and plays important regulatory roles in the degradation of intracellular components through the lysosomes [1,2]
The autophagy–lysosomal pathway was considered to play essential roles in maintaining metabolic homeostasis and regulating lipid metabolism [29], but whether fat and fatty acids (FAs) can regulate the activity of the autophagosome–lysosome pathway remains unknown
We identified nine genes involved in the autophagosome–lysosome pathway from P. fulvidraco, and explored their tissue distribution profiles and transcriptional responses to a high-fat diet
Summary
Autophagy is significantly conserved during evolution and plays important regulatory roles in the degradation of intracellular components through the lysosomes [1,2]. The autophagy–lysosome pathway plays crucial roles in the maintenance of intracellular homeostasis by the degradation of damaged components. The important pathway involve many crucial genes and proteins, some of which have been identified but their specific functions are largely unknown. Genes 2019, 10, 751 endosome tethering) and HOPS (homotypic fusion and protein sorting) belong to the members of the. HOPS controls the membrane fusion at the vacuolar lysosomes [5]. Class C Vps members include vacuolar protein sorting-associated protein (Vps) 11 (Vps11), Vps, Vps and
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