Abstract
The proteins CITED belong to a family of non-DNA-binding transcriptional co-regulators involved in the regulation of various transcriptional responses. Previous studies suggest that members of CITED family may function in response to hypoxia in mammals. however, the molecular and functional information on CITED genes in aquaculture fish is unclear. Here, we characterized and examined the transcriptional patterns of CITED1 and CITED2 genes in the hypoxia-sensitive blunt snout bream (Megalobrama amblycephala). Blunt snout bream CITED1 and CITED2 genes shared a relatively low sequence identity of 45%. CITED1 and CITED2 mRNAs were widely transcribed in adult tissues. During embryogenesis, CITED1 mRNA was significantly transcribed at 4, 24, 28, 40, and 44 hpf, whereas CITED2 mRNA levels fluctuated from the zygote to 44 hpf larval stage. Whole-mount in situ hybridization demonstrated that CITED1 and CITED2 mRNAs were detected in the brain at 12 hpf, brain and gut at 24 hpf, and brain at 36 hpf. In addition, low expression of CITED1 mRNA was detected in the tailbud at 24 hpf. The results of acute hypoxia experiment showed that CITED1 and CITED2 mRNAs were markedly upregulated in the kidney and downregulated in the liver, brain, gill, and heart under hypoxia. Embryos in hypoxic conditions at different developmental stages showed a significant increase in mRNA levels of CITED1 and CITED2. These results provide a new insight into the divergence of CITED1 and CITED2 genes and their transcriptional responses to hypoxia.
Highlights
The proteins CITED, cAMP-responsive element-binding protein (CBP)/p300-interacting transactivator with glutamic acid (E) and aspartic acid (D)-rich C-terminal domain, are involved in the modulation of a variety of cellular and developmental processes and responses to environmental stimuli at the transcriptional level in mammals (Dunwoodie et al, 1998; Yahata et al, 2001).CITED1/-2 Genes Under HypoxiaTo date, four different homologs (CITED1-4) have been reported in vertebrates (Bhattacharya et al, 1999)
Multiple alignments suggest that both CITED1 and CITED2 peptides from blunt snout bream were predicted to consist of CR1 and CR2 domains displaying a leucine-rich nuclear-export signal (Leu-rich NES), as observed in other species. (Figure 1)
The phylogenetic tree demonstrated that CITED1 and CITED2 of blunt snout bream are well clustered with their orthologs in other species (Figure 2)
Summary
The proteins CITED, cAMP-responsive element-binding protein (CBP)/p300-interacting transactivator with glutamic acid (E) and aspartic acid (D)-rich C-terminal domain, are involved in the modulation of a variety of cellular and developmental processes and responses to environmental stimuli at the transcriptional level in mammals (Dunwoodie et al, 1998; Yahata et al, 2001).CITED1/-2 Genes Under HypoxiaTo date, four different homologs (CITED1-4) have been reported in vertebrates (Bhattacharya et al, 1999). The proteins CITED, cAMP-responsive element-binding protein (CBP)/p300-interacting transactivator with glutamic acid (E) and aspartic acid (D)-rich C-terminal domain, are involved in the modulation of a variety of cellular and developmental processes and responses to environmental stimuli at the transcriptional level in mammals (Dunwoodie et al, 1998; Yahata et al, 2001). CITED2, originally called as MRG1 (MSG1-related gene 1) shares transcription-activating CR1 (14 amino acid residues) and CR2 (∼50 amino acid residues) domains with CITED1 (Shioda et al, 1997). Members of CITED family may bind to CBP/p300 with a strong affinity and negatively regulate HIF-1 transactivation (Bhattacharya et al, 1999; Ng et al, 2010)
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