Molecular Characterization of PGC-1β (PPAR Gamma Coactivator 1β) and its Roles in Mitochondrial Biogenesis in Blunt Snout Bream (Megalobrama amblycephala)

Kangle Lu,Tomas Policar,Samad Rahimnejad,Xiaojun Song

doi:10.3390/ijms21061935

Abstract

This study aimed at achieving the molecular characterization of peroxisome proliferator-activated receptor-gamma coactivator 1β (PGC-1β) and exploring its modulatory roles in mitochondria biogenesis in blunt snout bream (Megalobrama amblycephala). A full-length cDNA of PGC-1β was cloned from liver which covered 3110 bp encoding 859 amino acids. The conserved motifs of PGC-1β family proteins were gained by MEME software, and the phylogenetic analyses showed motif loss and rearrangement of PGC-1β in fish. The function of PGC-1β was evaluated through overexpression and knockdown of PGC-1β in primary hepatocytes of blunt snout bream. We observed overexpression of PGC-1β along with enhanced mitochondrial transcription factor A (TFAM) expression and mtDNA copies in hepatocytes, and its knockdown led to slightly reduced NRF1 expression. However, knockdown of PGC-1β did not significantly influence TFAM expression or mtDNA copies. The alterations in mitochondria biogenesis were assessed following high-fat intake, and the results showed that it induces downregulation of PGC-1β. Furthermore, significant decreases in mitochondrial respiratory chain activities and mitochondria biogenesis were observed by high-fat intake. Our findings demonstrated that overexpression of PGC-1β induces the enhancement of TFAM expression and mtDNA amount but not NRF-1. Therefore, it could be concluded that PGC-1β is involved in mitochondrial biogenesis in blunt snout bream but not through PGC-1β/NRF-1 pathway.

Highlights

The peroxisome proliferator-activated receptor-gamma coactivator 1 (PGC-1) family including PGC-1α, proliferator-activated receptor-gamma coactivator 1β (PGC-1β), and PRC are critical transcriptional coactivators regulating mitochondrial biogenesis and energy metabolism in mammals [1]
The objectives of the present research were to (1) achieve the molecular characterization of PGC-1β and (2) to assess the role of PGC-1β in the regulation of mitochondria biogenesis and bioenergetics in blunt snout bream (Megalobrama amblycephala), which is a popular candidate for aquaculture industry in China due to its rapid growth, tender flesh, and high disease resistance
Given the PGC-1 family members contain a conserved RNA recognition motif domain in the C-terminal part, using SMART software, we found that the M. amblycephala PGC-1β protein contains an RRM domain in C-terminal

Summary

Introduction

The peroxisome proliferator-activated receptor-gamma coactivator 1 (PGC-1) family including PGC-1α, PGC-1β, and PRC are critical transcriptional coactivators regulating mitochondrial biogenesis and energy metabolism in mammals [1]. PGC-1α was firstly characterized as a stimulator of thermogenin in mice [2], and later PGC-1β and PRC were discovered by searching for PGC1α homologues through database [3] Among these three family members, PGC-1α has been studied mostly and is known to exert an array of well-defined roles in mammals [4]. Despite the establishment of PGC-1α/NRF-1/TFAM pathway in mammals, this axis has been rarely studied in lower vertebrates including fish [5,6] It has been reported by several authors that the changes of PGC-1α in the temperature- and nutrition-induced mitochondrial remodeling in fish are inconsistent with its central role as a master regulator [6,7]. It has been pointed out that the PGC-1α/NRF-1 pathway is probably disrupted in fish because of fish PGC1α orthologs insertion in the region severing as NRF-1 binding domain in mammals [8,9]

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Methods

Results