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Gao S.,University of Michigan | Gao S.,Institute of Evolution and Marine Biodiversity | Lu L.,Ocean University of China | Bai Y.,University of Michigan | And 3 more authors.
FASEB Journal | Year: 2014

Hypoxia-inducible factors (HIFs) are master regulators of the transcriptional response to hypoxia. To gain insight into the structural and functional evolution of the HIF family, we characterized the HIFα gene from amphioxus, an invertebrate chordate, and identified several alternatively spliced HIFα isoforms. Whereas HIFα Ia, the full-length isoform, contained a complete oxygen-dependent degradation (ODD) domain, the isoforms Ib, Ic, and Id had 1 or 2 deletions in the ODD domain. When tagged with GFP and tested in mammalian cells, the amphioxus HIFα Ia protein level increased in response to hypoxia or CoCl2 treatment, whereas HIFα Ib, Ic, and Id showed reduced or no hypoxia regulation. Deletion of the ODD sequence in HIFα Ia up-regulated the HIFα Ia levels under normoxia. Gene expression analysis revealed HIFα Ic to be the predominant isoform in embryos and larvae, whereas isoform Ia was the most abundant form in the adult stage. The expression levels of Ib and Id were very low. Hypoxia treatment of adults had no effect on the mRNA levels of these HIFα isoforms. Functional analyses in mammalian cells showed all 4 HIFα isoforms capable of entering the nucleus and activating hypoxia response element-dependent reporter gene expression. The functional nuclear location signal (NLS) mapped to 3 clusters of basic residues. 775KKARL functioned as the primary NLS, but 737KRK and 754KK also contributed to the nuclear localization. All amphioxus HIFα isoforms had 2 functional transactivation domains (TADs). Its C-terminal transactivation (C-TAD) shared high sequence identity with the human HIF-1α and HIF-2α C-TAD. This domain contained a conserved asparagine, and its mutation resulted in an increase in transcriptional activity. These findings reveal many ancient features of the HIFα family and provide novel insights into the evolution of the HIFα family. © FASEB.


Li L.,Institute of Evolution and Marine Biodiversity | Li L.,Ocean University of China | Ji D.,Institute of Evolution and Marine Biodiversity | Ji D.,Ocean University of China | And 5 more authors.
Gene | Year: 2015

Snake venom neurotoxins and lymphocyte antigen-6 (Ly6) family members identified in many metazoans possess conserved LU domain containing eight or ten conserved cysteine residues which form 4 to 5 conserved disulfide bonds. They are found to execute a wide variety of biological effects, but information regarding Ly6 superfamily in zebrafish remains rather limited. Here we identified a novel Ly6 gene located on the chromosome 15 in zebrafish, and named it lypc highlighting its predominant expression in the pigment cells. Both homology modeling and sequence comparison revealed that lypc has features typical of Ly6 family members. Whole mount in situ hybridization showed that lypc was expressed in the trunk pigment cells and retinal pigment cells. Moreover, real-time quantitative PCR demonstrated that the expression of lypc was subjected to diurnal variation regulation, i.e. the expression of lypc displays a clear rhythmic pattern, and dark exposure apparently stimulated its expression. Collectively, these data indicate that lypc is a novel dark-inducible Ly6 member with a predominant expression in the pigment cells of zebrafish, laying a foundation for further elucidation of its functions. © 2015 Elsevier B.V.


Liu S.,Institute of Evolution and Marine Biodiversity | Liu S.,Ocean University of China | Hu G.,Institute of Evolution and Marine Biodiversity | Hu G.,Ocean University of China | And 4 more authors.
Fish and Shellfish Immunology | Year: 2013

Galectins are a family of Ca2+-independent soluble lectins characterized by their affinity to β-galactosides. Mammalian galectins have been shown to play a defense role against certain bacteria, fungi and viruses. However, the immunological functions of galectins in fish is poorly characterized. Here we demonstrated that the expression of galectin-1 gene from the flounder Paralichthys olivaceus was decreased in the initial 8h after challenge with poly I:C, then increased markedly from 24h onwards, and the recombinant galectin-1 was able to neutralize the lymphocystis disease virus (LCDV), inhibiting the formation of cytopathic effects. In addition, the recombinant galectin had apotential anti-inflammatory activity against infection by LCDV, and was able to restrain the overexpression of the anti-viral protein gene mx against virus infection. These results indicate that flounder galectin-1 has an anti-viral activity, capable of reducing LCDV pathogenicity. •We describe the expression of Japanese flounder galectin-1in head kidney after injection with poly I:C.•Recombinant fGLec-1 possesses the capacity to reduce LCDV pathogenicity.•Recombinant fGLec-1 has an anti-inflammatory activity against infection by LCDV. © 2013 Elsevier Ltd.


Li M.,Institute of Evolution and Marine Biodiversity | Li M.,Ocean University of China | Gao Z.,Institute of Evolution and Marine Biodiversity | Gao Z.,Ocean University of China | And 4 more authors.
Endocrinology | Year: 2014

Amphioxus belongs to the subphylum cephalochordata, an extant representative of the most basal chordates. Despite many studies on the endocrine system of amphioxus, no evidence showed the presence of pituitary hormones. In this study,we clearly demonstrated the existence of a functional GH-like hormone in amphioxus, which is able to bind purified GH receptors, stimulate IGF-I expression, promote growth rate of fish, and rescue embryonic defects caused by a shortage of GH. We also showed the presence of a GH/prolactin-like-binding protein containing the entire hormone binding domain of GH/prolactin receptors in amphioxus, which is widely expressed among tissues, and interacts with the GH-like hormone. It is clear from these results that the GH/GH receptor-like system is present in amphioxus and, hence, in all classes of chordates. Notably, the GH-like hormone appears to be the only member of the vertebrate pituitary hormones family in amphioxus, suggesting that the hormone is the ancestral peptide that originated first in the molecular evolution of the pituitary hormones family in chordates. These data collectively suggest that a vertebrate-like neuroendocrine axis setting has already emerged in amphioxus, which lays a foundation for subsequent formation of hypothalamic-pituitary system in vertebrates. Copyright © 2014 by the Endocrine Society

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