Glucose-6-phosphate dehydrogenase in blunt snout bream Megalobrama amblycephala: molecular characterization, tissue distribution, and the responsiveness to dietary carbohydrate levels

Abstract

This study aimed to characterize the full-length cDNA of glucose-6-phosphate dehydrogenase (G6PD) from Megalobrama amblycephala with its responses to dietary carbohydrate levels characterized. The cDNA obtained covered 2768 bp with an open reading frame of 1572 bp. Sequence alignment and phylogenetic analysis revealed a high degree of conservation (77-97%) among most fish and other higher vertebrates. The highest transcription of G6PD was observed in kidney followed by liver, whereas relatively low abundance was detected in eye. Then, the transcriptions and activities of G6PD as well as lipid contents were determined in the liver, muscle, and the adipose tissue of fish fed two dietary carbohydrate levels (30 and 42%) for 12 weeks. Hepatic transcriptions of fatty acid synthetase (FAS), acetyl-CoA carboxylase α (ACCα), sterol regulatory element-binding protein-1 (SREBP1), and peroxisome proliferator-activated receptor γ (PPARγ) were also measured to corroborate the lipogenesis derived from carbohydrates. The G6PD expressions and activities in both liver and the adipose tissue as well as the lipid contents in whole-body, liver, and the adipose tissue all increased significantly after high-carbohydrate feeding. Hepatic transcriptions of FAS, ACCα, SREBP1, and PPARγ were also up-regulated remarkably by the intake of a high-carbohydrate diet. These results indicated that the G6PD of M. amblycephala shared a high similarity with that of other vertebrates. Its expressions and activities in tissues were both highly inducible by high-carbohydrate feeding, as also held true for the transcriptions of other enzymes and/or transcription factors involved in lipogenesis, evidencing an enhanced lipogenesis by high dietary carbohydrate levels.

Sequential Activations of ChREBP and SREBP1 Signals Regulate the High-Carbohydrate Diet-Induced Hepatic Lipid Deposition in Gibel Carp (Carassius gibelio)

“…We further showed the excessive lipid deposition mainly resulted from the supraphysiological lipogenesis but not decreased lipolysis in the liver of gibel carp. These results are similar to the previous studies in various of fish species [37][38][39]. In the present study, the lipolysis level even elevated at 6 th and 8 th week.…”

“…However, the activation and contribution mode of SREBP1 in HCD-induced lipogenesis have not been deciphered in the previous studies. In the present study, the expression and activation level of SREBP1 were elevated by HCD, those were consisted with previous studies in fish [10,37,42]. Notably, we found that the SREBP1 signal showed an obvious decrease from 6 th week to 8 th week, when we compared the dynamic changes of expression and activation level of SREBP1 within HCD group.…”

Metabolic responses of hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ E. lanceolatus ) induced by different feeding modes: Effects on growth, serum biochemical indices, intestinal digestion and hepatic metabolism of glucose and lipid

“…Due to nutritional or hormone conditions change, organism would regulate fatty acid synthesis rate. ACC plays a necessary role in this regulation (Jiang et al, 2018; Shiau & Chin, 1999). As a regulatory factor that catalyses the key steps of lipid synthesis, FAS catalyses the synthesis of fatty acids from acetyl‐CoA and malonyl‐CoA (Zuo et al, 2017).…”

Effect of Dietary Lipid Level on Growth Performance, Body Composition, and Physiometabolic Responses of Genetically Improved Farmed Tilapia (GIFT) Juveniles Reared in Inland Ground Saline Water

“…Glucose-6-phosphate dehydrogenase (G6PDH) is a key enzyme in catalyzing nicotinamide adenine dinucleotide phosphate hydrogen (NADPH) production, essential for hepatic fatty acid biosynthesis [ 79 ]. In the present study, the G6PDH activities of the liver in relation to increasing dietary lipid exhibited a reducing trend from lower lipid to high-lipid diets.…”