Dynamic transcriptional regulation of autocrine/paracrine igfbp1, 2, 3, 4, 5, and 6 in the skeletal muscle of the fine flounder during different nutritional statuses

Abstract

The IGF-binding proteins (IGFBPs) play a dual role in the regulation of the activity and bioavailability of IGFs in different tissues. Diverse evidence has shown that IGFBPs can inhibit and/or potentiate IGF actions. In this study, igfbp1, 2, 3, 4, 5, and 6 were isolated in the fine flounder, a flat fish species that shows slow growth and inherent Gh resistance in muscle. Subsequently, the expression of all igfbps was assessed in the skeletal muscle of flounder that underwent different nutritional statuses. igfbp1 was not expressed in muscle during any of the nutritional conditions, whereas igfbp3 and igfbp5 were the lowest and the highest igfbps expressed respectively. A dynamic expression pattern was found in all the igfbps expressed in skeletal muscle, which depended on the nutritional status and sampling period. During the fasting period, igfbp2, 4, and 5 were downregulated, whereas igfbp3 was upregulated during part of the fasting period. The restoration of food modulated the expression of the igfbps dynamically, showing significant changes during both the long-and short-term refeeding. igfbp3 and igfbp6 were downregulated during short-term refeeding, whereas igfbp5 was upregulated, and igfbp2 and igfbp4 remained stable. During long-term refeeding, the expression of igfbp2, 4, 5, and 6 increased, while igfbp3 remained unchanged. In conclusion, this study shows for the first time the isolation of all igfbps in a single fish species, in addition to describing a dynamic nutritional and time-dependent response in the expression of igfbps in the skeletal muscle of a nonmammalian species.

Effects of phytoestrogens on growth-related and lipogenic genes in rainbow trout (Oncorhynchus mykiss)

“…Conversely, effects of genistein on expression of igfbps likely reflect regulation by estrogen receptor-independent mechanisms since the pattern of regulation does not reflect treatment estrogenicity. Although roles of IGFBPs in fish muscle remain to be fully characterized, increased expression of igfbp4 and igfbp5b1 are correlated with periods of refeeding and growth (Gabillard et al, 2006;Bower et al, 2008;Safian et al, 2012;Cleveland and Weber, 2014b) or anabolic conditions in cell culture (Bower and Johnston, 2010b), suggesting these proteins promote anabolic activity in salmonid muscle. In mammals the growthpromoting effects of IGFBP5 are attributed to its high binding affinity for the extracellular matrix, which reduces its affinity for IGF1 and IGF2 by approximately 15-fold, possibly potentiating the binding of the IGF peptides to IGF receptors on the cell surface (Clemmons, 1998;Duan and Xu, 2005).…”

Molecular characterization and expression patterns of insulin-like growth factor-binding protein genes in postnatal Nanjiang brown goats

“…In addition, IGFBP-4 knockout mice show reduced prenatal growth (Ning et al, 2008). More recent studies have shown that IGFBP-5 plays a key role in muscle growth and differentiation (Mukherjee et al, 2008;Duan et al, 2010;Safian et al, 2012). However, IGFBP-5 knockout mice had no obvious abnormalities in muscle development, probably due to the compensatory effects of other IGFBPs (Ning et al, 2007).…”

Cloning, molecular characterization and expression analysis of insulin-like growth factor binding protein-2 (IGFBP-2) cDNA in goldfish, Carassius auratus

“…However, in rainbow trout, IGFBP-2 displayed no effect of starvation followed by a peak of mRNA abundance after 7 days of refeeding in liver, whereas starvation led to a decrease of the IGFBP-2 mRNA level in muscle (Gabillard et al 2006). Recently, the similar result was observed in the muscle of fine flounder, IGFBP-2 mRNA levels decreasing during fasting and returning to basal level during long-term refeeding (Safian et al 2012). To better understand the actions of IGFBP-2 in fish growing axis, in the present study, we investigated the mRNA expression levels of goldfish IGFBP-2 in hypothalamus, pituitary and liver tissues of goldfish under the condition of feeding, fasting and refeeding, respectively.…”

“…Over the past few years, IGFBP-2 cDNA had been cloned and characterized in many fish species, including zebra fish (Danio rerio) (Duan et al 1999;Zhou et al 2008), goby (Gillichthys mirabilis) (Gracey et al 2001), gilthead sea bream (Sparus aurata) (Funkenstein et al 2002), common carp (Cyprinus carpio) ), yellowtail (Seriola quinqueradiata) (Pedroso et al 2009), orange-spotted grouper (Epinephelus coioides) (Chen et al 2010), chinook salmon (Oncorhynchus tshawytscha) (Shimizu et al 2011), Atlantic croaker (Micropogonias undulatus) (Rahman and Thomas 2011), fine flounder (Paralichthys adspersus) (Safian et al 2012) and Japanese flounder (Paralichthys olivaceus) (Zhang et al 2013). Together these results, it shows that the structure of fish IGFBP-2 is conserved with highly degree to their mammalian counterparts, suggesting its conserved functions.…”

“…In primary cultured common carp hepatocytes, GH could also reduce IGFBP-2 mRNA expression in involving the MAPK and PI3kinase-signaling pathways ). However, in fine flounder, it showed that IGFBP-2 mRNA expression was downregulated during the fasting period in the skeletal muscle (Safian et al 2012). In fish and other vertebrates, somatic growth is mainly under the control of the growing axis (hypothalamus-pituitary-liver axis).…”