Isolation of two functional retinoid X receptor subtypes from the Ixodid tick, Amblyomma americanum (L.)

Guo, Xiaohu; Xu, Qing; Harmon, Margaret A.; Jin, Xiaojing; Laudet, Vincent; Mangelsdorf, David J.; Palmer, Melanie J.

doi:10.1016/s0303-7207(98)00073-2

Cited by 61 publications

(42 citation statements)

References 54 publications

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“…Although the resulting sequence terminated with a poly A tail, the absence of a consensus polyadenylation signal (AAG AAA instead of AATAAA) suggested that the 3 UTR, as well as the 5 UTR, was incomplete. No variant transcripts were identified during RACE-PCR experiments, suggesting that the BgRXR gene does not produce alternatively spliced or truncated forms of the mRNA encoding protein isoforms, although this phenomenon has been described for RXRs in other organisms (Guo et al 1998, Kostrouch et al 1998.…”

Section: Isolation Of Bgrxr From the Mollusk B Glabratamentioning

confidence: 84%

“…3). However, the RXR/USPs from the former group do not activate transcription in the presence of either 9-cis RA or a synthetic retinoid (Guo et al 1998). It is clear that vertebrate-like RXRs are absent from both Drosophila (Adams et al 2000) and the nematode Caenorhabditis elegans (Sluder et al 1999), and the latter even lacks a USP homolog, although one is present in the parasitic nematode Dirofilaria immitis (Sluder & Maina 2001, Shea et al 2004.…”

Section: Discussionmentioning

confidence: 99%

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A conserved retinoid X receptor (RXR) from the mollusk Biomphalaria glabrata transactivates transcription in the presence of retinoids

Bouton¹,

Escrivà²,

Mendonça³

et al. 2005

Journal of Molecular Endocrinology

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Retinoid X receptors (RXR) are members of the nuclear receptor superfamily of ligand-activated transcription factors that have been characterized in a wide variety of metazoan phyla. They act as heterodimer partners of other nuclear receptors, and in vertebrates also activate transcription as homodimers in the presence of a ligand, 9-cis retinoic acid. In order to test the hypothesis that retinoic acid signaling pathways involving RXRs are present in the Lophotrochozoa, we have sought to isolate conserved members of this family from the platyhelminth parasite Schistosoma mansoni and its intermediate host, the mollusk Biomphalaria glabrata. Here we report that an RXR ortholog from B. glabrata (BgRXR) is better conserved, compared with mouse RXR , both in the DNA-binding domain (89% identity) and in the ligand-binding domain (LBD) (81% identity), than are arthropod homologs. In EMSA, BgRXR binds to the direct repeat response element DR1 as a homodimer or as a heterodimer with mammalian RAR , LXR, FXR or PPAR . When transfected alone into mammalian cell lines, BgRXR transactivated transcription of a reporter gene from the Apo-A1 promoter in the presence of 9-cis retinoic acid or DHA. Constructs with the Gal4 DNA binding domain fused to the hinge and LBDs of BgRXR were used to show that ligand-dependent activation of transcription by BgRXR required its intact AF-2 activation domain, and that the LBD can form homodimers. Finally, the binding of 9-cis retinoic acid preferentially protected the LBD of BgRXR from degradation by trypsin in a proteolysis protection assay. Our results show that BgRXR binds and is activated by retinoids and suggest that retinoid signaling pathways are conserved in the Lophotrochozoa. The nucleotide sequence reported in this paper has been submitted to the GenBank/EBI Data Bank with accession no. AY048663.

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Section: Isolation Of Bgrxr From the Mollusk B Glabratamentioning

confidence: 84%

Section: Discussionmentioning

confidence: 99%

A conserved retinoid X receptor (RXR) from the mollusk Biomphalaria glabrata transactivates transcription in the presence of retinoids

Bouton¹,

Escrivà²,

Mendonça³

et al. 2005

Journal of Molecular Endocrinology

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“…All the identified RXR homologs have similar domains, but they vary in the association of those domains (Bonneton et al 2003). RXR homologs have deduced LBD sequences that are more similar to the invertebrates, such as locusts (Hayward et al 1999), ticks (Guo et al 1998), cockroaches (Maestro et al 2005), and vertebrate RXR (data not shown). RXRa (human) is well conserved in that of crustacean RXR's, implying that crustacean RXRs might be more similar to vertebrate RXR than to insect USP in ligand binding (Billas et al 2001, Carmichael et al 2005.…”

Section: Discussionmentioning

confidence: 96%

Molecular cloning and sequence of retinoid X receptor in the green crab Carcinus maenas: a possible role in female reproduction

Nagaraju

Rajitha

Borst³

2011

Journal of Endocrinology

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Retinoid X receptor (RXR) belongs to an ancient superfamily of nuclear hormone receptors, and plays an important role in reproduction of vertebrates. However, the reproductive role of RXR has not been clarified in crustaceans. In this investigation, we first report the cloning of two alternative splice variants of RXR cDNA from green crab ovarian RNA. RXR mRNA levels were quantified in different vitellogenic stages of the crab hepatopancreas (HP) and ovary. The expression of RXR mRNA relative to the arginine kinase mRNA was significantly increased in the HP of vitellogenic crabs in a stage-dependent manner. The relative levels of RXR mRNA in the ovary were significantly lower in vitellogenic stage III crabs than in crabs in the other three stages. These data indicate that the HP and ovary of the crab are capable of expressing RXR, which may regulate, in part, vitellogenesis in the crab. We also examined the effects of methyl farnesoate (MF) and RXR-dsRNA treatments on vitellogenin and RXR gene expression. Vitellogenin and RXR mRNA levels in HP and ovarian fragments incubated in MF were significantly (P!0 . 001) higher than in control tissue fragments prepared from the same animal. Treatment of crabs with RXR-dsRNA significantly (P!0 . 001) reduced mRNA levels for RXR and for vitellogenin as well as MF levels in hemolymph. These results indicate that, MF and RXR form a complex (MF-RXR) directly and together stimulate ovarian development in these green crabs. This interaction of RXR, MF, and ovary development axis is a novel finding and is the first report to the best of our knowledge.

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“…The jRXR has higher homology with the human RXR (78% homology in the DBD and an astonishing 79% homology in the LBD) than with the Drosophila RXR homologue USP (figs 3, 4). The arthropod ixodid tick possesses two RXR isoforms which have a DBD closer to that of USP yet have LBDs closer to vertebrate RXRs suggesting that the LBD of the RXR has been well conserved from cnidarians to vertebrates and through the early branch that gives rise to the arthropod lineage [82] (figs 3, 4). Neither the USP, nor the tick RXRs, are thought to bind the ligand 9-cis-retinoic acid, while the jRXR is capable of binding this compound with higher affinity than the mammalian RXR [71].…”

Section: The Ligand-binding Domainmentioning

confidence: 99%

Origins and evolutionary diversification of the nuclear receptor superfamily

Owen

Zelent

2000

Cellular and Molecular Life Sciences (CMLS)

103

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Nuclear receptors (NRs), which include those for steroid and thyroid hormones as well as retinoids, are encoded by a large gene superfamily that has evolved to regulate nearly every facet of metazoan life, from development to basic metabolism. This article reviews the conservation in structure and function of distinct receptors across different species and attempts to draw conclusions as to the evolution of this gene superfamily. Although sequences related to NRs can be found in plants and yeast, gene sequence analyses suggest that the NR ancestor(s) first appeared in the early metazoans and subsequently diversified into the six receptor sub-families, which were already recognisable at the time of the Arthropoda-Chordata split over 700 million years ago. At the time when a primitive NR emerged, the basic components of the transcription regulatory machinery, which are conserved from yeast to vertebrates, were already in place and the ancestral NR must have evolved with the ability to communicate with them. The first such NRs likely acted as monomers and in a ligand-independent fashion. As members of the NR superfamily acquired the ability to hetero- and homodimerise, and to bind and be regulated by ligands, the functional complexity of the NR superfamily increased. This exponentially increasing complexity subsequently provided a potential driving force for evolution of higher organisms by supplying a sophisticated regulatory gene network that could control complex physiological processes during development and in adult organisms.

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Isolation of two functional retinoid X receptor subtypes from the Ixodid tick, Amblyomma americanum (L.)

Cited by 61 publications

References 54 publications

A conserved retinoid X receptor (RXR) from the mollusk Biomphalaria glabrata transactivates transcription in the presence of retinoids

A conserved retinoid X receptor (RXR) from the mollusk Biomphalaria glabrata transactivates transcription in the presence of retinoids

Molecular cloning and sequence of retinoid X receptor in the green crab Carcinus maenas: a possible role in female reproduction

Origins and evolutionary diversification of the nuclear receptor superfamily

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