Trichoplax adhaerens reveals an endocrine-like network sensitive to 9-cis-retinoic acid at the base of metazoan evolution
- Published
- Accepted
- Subject Areas
- Evolutionary Studies, Genomics, Molecular Biology, Diabetes and Endocrinology
- Keywords
- Trichoplax adhaerens, RXR, 9-cis retinoic acid, food, ERR, HNF4, COUP, nuclear receptor
- Copyright
- © 2017 Novotný et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2017. Trichoplax adhaerens reveals an endocrine-like network sensitive to 9-cis-retinoic acid at the base of metazoan evolution. PeerJ Preprints 5:e2945v1 https://doi.org/10.7287/peerj.preprints.2945v1
Abstract
Trichoplax adhaerens, the only known species of Placozoa is likely to be closely related to an early metazoan that preceded branching of Cnidaria and Bilateria. This animal species is surprisingly well adapted to free life in the World Ocean inhabiting tidal costal zones of oceans and seas with warm to moderate temperatures and shallow waters. The genome of T. adhaerens (sp. Grell) includes four nuclear receptors, namely homologues of RXR (NR2B), HNF4 (NR2A), COUP (NR2F) and ERR (NR3B) that show a high degree of similarity with human homologues. In the case of RXR, the sequence identity to human RXR alpha reaches 81% in the DNA binding domain and 70 % in the ligand binding domain. We show that T. adhaerens RXR (TaRXR) binds 9-cis retinoic acid (9-cis-RA) with high affinity, as well as high specificity and that exposure of T. adhaerens to 9-cis-RA regulates the expression of the putative T. adhaerens homologue of vertebrate L-malate-NADP+ oxidoreductase (EC 1.1.1.40) which in vertebrates is regulated by a heterodimer of RXR and thyroid hormone receptor. Treatment by 9-cis-RA alters the relative expression profile of T. adhaerens nuclear receptors, suggesting the existence of natural ligands. Keeping with this, algal food composition has profound effect on T. adhaerens growth and appearance. Our results uncover an endocrine-like network of nuclear receptors sensitive to 9-cis-RA in T. adhaerens and support the existence of a ligand-sensitive network of nuclear receptors at the base of metazoan evolution.
Author Comment
This is a submission to PeerJ for review.
Supplemental Information
Supplementary file S1
Sequences for ClustalO alignment of RXR sequences from selected species shown in Fig.1.
Supplementary file S2. Alignments of HNF4, COUP and ERR sequences from selected species
ClustalO alignments of HNF4, COUP and ERR sequences from selected species.
Supplementary file S3. Identification of T. adhaerens predicted L-malate-NADP+ oxidoreductase)
Identification of T. adhaerens predicted L-malate-NADP+ oxidoreductase).
Supplementary file S4. qRT-PCR and ddPCR data
Raw data obtained for quantitative analysis of the relative expression of T. adhaerens NRs and expression of the T. adhaerens homologue of EC 1.1.1.40.
Supplementary file S5 - part A. Images of T. adhaerens incubated with specific algal food
Images of T. adhaerens that were incubated with specific algal food, copied to one assembled figure which was used for analysis using ImageJ program. Images were saved in JPG format and divided to two parts in order to comply with maximum space allowed for Supplementary files. Incubation of T. adhaerens with food composed of all three tested algae was done in duplicate. The second duplicate is provided in Part B.
Supplementary file S5 - part B. Images of T. adhaerens incubated with specific algal food
Images of T. adhaerens that were incubated with specific algal food, copied to one assembled figure which was used for analysis using ImageJ program. Images were saved in JPG format and divided to two parts in order to comply with maximum space allowed for Supplementary files. Part B is showing the images of T. adhaerens fed with food composed of all three tested algae that was done in duplicate. All other images are shown in Part A.
Supplementary file S6. Image analysis of T. adhaerens cultures fed with different algal foods
Raw data for the analysis shown in Fig. 8.