AUTHOR=Sun Yuan , Guo Hong-Hong , Guo Dan-Dan , Jiang Xia-Yun , Zou Shu-Ming 

TITLE=Divergence of Genes Encoding CITED1 and CITED2 in Blunt Snout Bream (Megalobrama amblycephala) and Their Transcriptional Responses to Hypoxia

JOURNAL=Frontiers in Physiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2018.00186

DOI=10.3389/fphys.2018.00186

ISSN=1664-042X

ABSTRACT=<p>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 <italic>CITED</italic> genes in aquaculture fish is unclear. Here, we characterized and examined the transcriptional patterns of <italic>CITED1</italic> and <italic>CITED2</italic> genes in the hypoxia-sensitive blunt snout bream (<italic>Megalobrama amblycephala</italic>). Blunt snout bream <italic>CITED1</italic> and <italic>CITED2</italic> genes shared a relatively low sequence identity of 45%. <italic>CITED1</italic> and <italic>CITED2</italic> mRNAs were widely transcribed in adult tissues. During embryogenesis, <italic>CITED1</italic> mRNA was significantly transcribed at 4, 24, 28, 40, and 44 hpf, whereas <italic>CITED2</italic> mRNA levels fluctuated from the zygote to 44 hpf larval stage. Whole-mount <italic>in situ</italic> hybridization demonstrated that <italic>CITED1</italic> and <italic>CITED2</italic> 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 <italic>CITED1</italic> mRNA was detected in the tailbud at 24 hpf. The results of acute hypoxia experiment showed that <italic>CITED1</italic> and <italic>CITED2</italic> 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 <italic>CITED1</italic> and <italic>CITED2</italic>. These results provide a new insight into the divergence of <italic>CITED1</italic> and <italic>CITED2</italic> genes and their transcriptional responses to hypoxia.</p>