Food restriction increase the expression of mTORC1 complex genes in the skeletal muscle of juvenile pacu (Piaractus mesopotamicus)

Abstract

Skeletal muscle is capable of phenotypic adaptation to environmental factors, such as nutrient availability, by altering the balance between muscle catabolism and anabolism that in turn coordinates muscle growth. Small noncoding RNAs, known as microRNAs (miRNAs), repress the expression of target mRNAs, and many studies have demonstrated that miRNAs regulate the mRNAs of catabolic and anabolic genes. We evaluated muscle morphology, gene expression of components involved in catabolism, anabolism and energetic metabolism and miRNAs expression in both the fast and slow muscle of juvenile pacu (Piaractus mesopotamicus) during food restriction and refeeding. Our analysis revealed that short periods of food restriction followed by refeeding predominantly affected fast muscle, with changes in muscle fiber diameter and miRNAs expression. There was an increase in the mRNA levels of catabolic pathways components (FBXO25, ATG12, BCL2) and energetic metabolism-related genes (PGC1α and SDHA), together with a decrease in PPARβ/δ mRNA levels. Interestingly, an increase in mRNA levels of anabolic genes (PI3K and mTORC1 complex: mTOR, mLST8 and RAPTOR) was also observed during food restriction. After refeeding, muscle morphology showed similar patterns of the control group; the majority of genes were slightly up- or down-regulated in fast and slow muscle, respectively; the levels of all miRNAs increased in fast muscle and some of them decreased in slow muscle. Our findings demonstrated that a short period of food restriction in juvenile pacu had a considerable impact on fast muscle, increasing the expression of anabolic (PI3K and mTORC1 complex: mTOR, mLST8 and RAPTOR) and energetic metabolism genes. The miRNAs (miR-1, miR-206, miR-199 and miR-23a) were more expressed during refeeding and while their target genes (IGF-1, mTOR, PGC1α and MAFbx), presented a decreased expression. The alterations in mTORC1 complex observed during fasting may have influenced the rates of protein synthesis by using amino acids from protein degradation as an alternative mechanism to preserve muscle phenotype and metabolic demand maintenance.

Fishing Into the MicroRNA Transcriptome

“…The pacu ( Piaractus mesopotamicus ), which is characterized by hardiness, fast growth, adaptation to artificial feeding and flavorsome meat (Castagnolli and Cyrino, 1986 ), is a valuable resource in Brazilian aquaculture (Urbinati and Gonçalves, 2005 ). Duran et al ( 2015 ) and Paula et al ( 2017 ) studied the role of skeletal muscle miRNAs in this Neotropical fish during development and under food restriction, respectively. Duran et al ( 2015 ) analyzed the impact of the miRNA-target interactions of miR-1/ hdac4 , miR-133-a/b/ srf , miR-206/ pax7 , and miR-499/ sox6 in fast- and slow-twitch skeletal muscles during growth.…”

Integrative MicroRNAome Analysis of Skeletal Muscle of Colossoma Macropomum (Tambaqui), Piaractus Mesopotamicus (Pacu), and the Hybrid Tambacu, based on Next-generation Sequencing Data.

“…Previous studies in our group have also analyzed the function of some miRNAs in the skeletal muscle of sh involving fasting and re-feeding treatments and muscle development [16], [17]. The authors observed that some miRNAs (miR-1, miR-133, miR-155, miR-206, and miR-499) presented a possible role in the regulation of factors related to muscle cell proliferation and differentiation and with muscle performance and metabolism, modulating the rate of protein synthesis and degradation.…”

Dietary histidine requirement of grow-out Nile tilapia (Oreochromis niloticus), based on growth performance, muscle development, expression of muscle-growth-related genes, and blood parameters

“…Dietary histidine requirement of grow-out Nile tilapia (Oreochromis niloticus), based on growth performance... Zaminhan-Hassemer et al Fish recruits new muscle fibers throughout their lifetime (Rowlerson and Veggetti, 2001), and hypertrophic and hyperplasic muscle growth may be influenced by nutrition (Dal Pai et al, 2000). Genomics assays have been used to better understand how nutrients can affect muscle-growth-related genes and metabolic responses in fish (Alami-Durante et al, 2010;De Paula et al, 2017). Muscle growth processes are regulated by the activation and proliferation of satellite cells and myogenic regulatory factors (MRF), such as MyoD and myogenin, and MyoD regulates myogenic activity in cell differentiation (Watabe, 1999).…”