Molecular characterization and expression analysis of five different elongation factor 1 alpha genes in the flatfish Senegalese sole (Solea senegalensis Kaup): Differential gene expression and thyroid hormones dependence during metamorphosis

Abstract

BackgroundEukaryotic elongation factor 1 alpha (eEF1A) is one of the four subunits composing eukaryotic translation elongation factor 1. It catalyzes the binding of aminoacyl-tRNA to the A-site of the ribosome in a GTP-dependent manner during protein synthesis, although it also seems to play a role in other non-translational processes. Currently, little information is still available about its expression profile and regulation during flatfish metamorphosis. With regard to this, Senegalese sole (Solea senegalensis) is a commercially important flatfish in which eEF1A gene remains to be characterized.ResultsThe development of large-scale genomics of Senegalese sole has facilitated the identification of five different eEF1A genes, referred to as SseEF1A1, SseEF1A2, SseEF1A3, SseEF1A4, and Sse42Sp50. Main characteristics and sequence identities with other fish and mammalian eEF1As are described. Phylogenetic and tissue expression analyses allowed for the identification of SseEF1A1 and SseEF1A2 as the Senegalese sole counterparts of mammalian eEF1A1 and eEF1A2, respectively, and of Sse42Sp50 as the ortholog of Xenopus laevis and teleost 42Sp50 gene. The other two elongation factors, SseEF1A3 and SseEF1A4, represent novel genes that are mainly expressed in gills and skin. The expression profile of the five genes was also studied during larval development, revealing different behaviours. To study the possible regulation of SseEF1A gene expressions by thyroid hormones (THs), larvae were exposed to the goitrogen thiourea (TU). TU-treated larvae exhibited lower SseEF1A4 mRNA levels than untreated controls at both 11 and 15 days after treatment, whereas transcripts of the other four genes remained relatively unchanged. Moreover, addition of exogenous T4 hormone to TU-treated larvae increased significantly the steady-state levels of SseEF1A4 with respect to untreated controls, demonstrating that its expression is up-regulated by THs.ConclusionWe have identified five different eEF1A genes in the Senegalese sole, referred to as SseEF1A1, SseEF1A2, SseEF1A3, SseEF1A4, and Sse42Sp50. The five genes exhibit different expression patterns in tissues and during larval development. TU and T4 treatments demonstrate that SseEF1A4 is up-regulated by THs, suggesting a role in the translational regulation of the factors involved in the dramatic changes that occurs during Senegalese sole metamorphosis.

Molecular cloning and characterization of the matricellular protein Sparc/osteonectin in flatfish, Scophthalmus maximus, and its developmental stage-dependent transcriptional regulation during metamorphosis

“…Although turbot metamorphosis is currently well described and the central role of thyroid hormone (THs) in this process is well established (Power et al, 2008;Infante et al, 2008;Roberto et al, 2009), there is no evidence for a putative regulatory role of THs on sparc expression. However, a number of different factors, such as parathyroid hormone (PTH; Nakajima et al, 2002) and dexamethasone (Sawhney, 2002), have been shown to regulate sparc and indicate that it might be an important intermediate in hormone action.…”

“…This metamorphic remodeling is characterized by several drastic physiological changes that involve a high active remodeling in different organs, such as skin (Campinho et al, 2007), the musculo-skeletal system (Saele et al, 2006), nervous system (Graf and Baker, 1990) and intestinal system (Tanaka et al, 1996). Although, turbot metamorphosis is now well described and the central role of thyroid hormone in this process is well established (Power et al, 2008;Infante et al, 2008;Roberto et al, 2009), few data are available concerning the regulation of potential specific target genes in the context of the gene network responsible for metamorphic remodeling of larval tissues. During metamorphosis, a significant number of transcription factors and developmental genes have a regulated expression, and it has specifically been shown that in the late stages of remodeling, genes that are necessary for cell proliferation, signal transduction, and cell-cell signaling are significantly upregulated (Kulkarni and Buchholz, 2013).…”

Identification of copper-responsive genes in an early life stage of the fathead minnow Pimephales promelas

“…These include the 40S ribosomal protein S15, the 60S ribosomal proteins L4, L5b, L12, L18, L21, L27, basic helix-loop-helix transcription factor, CCAAT/enhancer binding protein, translation elongation factors 1a and 1c, and translation initiation factor 2c. Five different elongation factors have been described in the metamorphoses of the Senegalese sole, suggesting that the larval stage may require tissue specific translation mechanisms (Infante et al 2008). Ribosome biogenesis in mice is known to be regulated by the mTOR pathway (Hannan et al 2003).…”

Deiodinases and thyroid metabolism disruption in teleost fish

“…deiodination (Heijlen et al, 2013;Infante et al, 2008;Itoh et al, 2010). Consequently, IDs are sensitive to T4/T3 concentrations ratio.…”