Dataset Information

The avian vitamin D receptors: primary structures and their origins.

ABSTRACT: cDNA clones encoding Japanese quail chorioallantoic membrane and chicken kidney 1,25-dihydroxyvitamin D3 receptors were isolated and the total 448-amino acid (aa) sequence was deduced. The sequences of the chicken and quail receptors are identical. The nucleotide and deduced amino acid sequences of the avian receptors are similar but not identical to the reported rat or human receptor sequences. There is a 78% similarity in the nucleotide sequences and 98.5% and 87.5% similarities in the amino acid sequences of the DNA-binding and ligand-binding domains, respectively. Two avian receptor proteins (58 and 60 kDa) arise from a single mRNA transcript by alternate initiation of translation. The avian 1,25-dihydroxyvitamin D3 receptors were produced using a bacterial expression system. Form A receptor was expressed from a cloned cDNA that contains the first translation signal (ATG) and corresponds with the 60-kDa avian receptor protein, and form B receptor was initiated from the third ATG on the same mRNA transcript to give rise to the 58-kDa protein. The cysteine-rich DNA-binding domain is almost conserved among human, rat, and avian receptors. The position of the nine cysteines was conserved in all three sequences. The avian receptor differs in the second zinc finger domain, where a methionine replaces a leucine, a serine replaces an asparagine, and a lysine replaces an arginine at aa 77, 83, and 87, respectively, of the avian sequence. The increased length of the avian receptor results from a 20-aa extension of the N-terminal region. RNA hybridization indicates there is a single mRNA species of approximately 2700 bp for both the chicken and quail receptors compared to 4400 bp for the rat transcript. Surprisingly, the translated avian sequence is larger (448 aa) than the 423-aa rat receptor protein. Therefore, our results confirm that despite the difference in molecular mass between different receptor proteins, there is a similarity in gene organization such that the DNA-binding and hormone-binding domains are positionally conserved from the C terminus.

SUBMITTER: Elaroussi MA

PROVIDER: S-EPMC45278 | biostudies-other | 1994 Nov

REPOSITORIES: biostudies-other

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The avian vitamin D receptors: primary structures and their origins.

Elaroussi M A MA Prahl J M JM DeLuca H F HF

Proceedings of the National Academy of Sciences of the United States of America 19941101 24

cDNA clones encoding Japanese quail chorioallantoic membrane and chicken kidney 1,25-dihydroxyvitamin D3 receptors were isolated and the total 448-amino acid (aa) sequence was deduced. The sequences of the chicken and quail receptors are identical. The nucleotide and deduced amino acid sequences of the avian receptors are similar but not identical to the reported rat or human receptor sequences. There is a 78% similarity in the nucleotide sequences and 98.5% and 87.5% similarities in the amino a ...[more]

PMID: 7972109

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Project description:BACKGROUND: Important knowledge about the role of vitamin A in vertebrate heart development has been obtained using the vitamin A-deficient avian in ovo model which enables the in vivo examination of very early stages of vertebrate heart morphogenesis. These studies have revealed the critical role of the vitamin A-active form, retinoic acid (RA) in the regulation of several developmental genes, including the important growth regulatory factor, transforming growth factor-beta2 (TGF?2), involved in early events of heart morphogenesis. However, this in ovo model is not readily available for elucidating details of molecular mechanisms determining RA activity, thus limiting further examination of RA-regulated early heart morphogenesis. In order to obtain insights into RA-regulated gene expression during these early events, a reliable in vitro model is needed. Here we describe a cell culture that closely reproduces the in ovo observed regulatory effects of RA on TGF?2 and on several developmental genes linked to TGF? signaling during heart morphogenesis. RESULTS: We have developed an avian heart forming region (HFR) cell based in vitro model that displays the characteristics associated with vertebrate early heart morphogenesis, i.e. the expression of Nkx2.5 and GATA4, the cardiogenesis genes, of vascular endothelial growth factor (VEGF-A), the vasculogenesis gene and of fibronectin (FN1), an essential component in building the heart, and the expression of the multifunctional genes TGF?2 and neogenin (NEO). Importantly, we established that the HFR cell culture is a valid model to study RA-regulated molecular events during heart morphogenesis and that the expression of TGF?2 as well as the expression of several TGF?2-linked developmental genes is regulated by RA. CONCLUSIONS: Our findings reported here offer a biologically relevant experimental in vitro system for the elucidation of RA-regulated expression of TGF?2 and other genes involved in vertebrate early cardiovascular morphogenesis.

Project description:The eukaryotic blood parasite genus Trypanosoma includes several important pathogens of humans and livestock, but has been understudied in wildlife broadly. The trypanosomes that infect birds are in particular need of increased attention, as these parasites are abundant and globally distributed, yet few studies have addressed their evolutionary origins and diversity using modern molecular and analytical approaches. Of specific interest are the deep evolutionary relationships of the avian trypanosomes relative to the trypanosome species that are pathogenic in humans, as well as their species level diversity in regions where they have been understudied such as North America. Here, we address these unresolved areas of study using phylogenomic data for two species of avian trypanosomes that were isolated as "bycatch" from host transcriptome assemblies, as well as a large 18S DNA barcode sequence dataset that includes 143 novel avian Trypanosoma 18S sequences from North America. Using a phylogenomic approach, we find that the avian trypanosomes are nested within a clade of primarily mammalian trypanosomes that includes the human pathogen Trypanosoma cruzi, and are paraphyletic with respect to the ruminant trypanosome Trypanosoma theileri. DNA barcode sequences showed that T. avium and an unidentified small, non-striated trypanosome that was morphologically similar to T. everetti are each represented by highly abundant and divergent 18S haplotypes in North America. Community-level sampling revealed that additional species-level Trypanosoma lineages exist in this region. We compared the newly sequenced DNA barcodes from North America to a global database, and found that avian Trypanosoma 18S haplotypes generally exhibited a marked lack of host specificity with at least one T. avium haplotype having an intercontinental distribution. This highly abundant T. avium haplotype appears to have a remarkably high dispersal ability and cosmopolitan capacity to evade avian host immune defenses, which warrant further study.

Dataset Information

The avian vitamin D receptors: primary structures and their origins.

Publications

The avian vitamin D receptors: primary structures and their origins.

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