Schistosoma mansoni (Platyhelminthes, Trematoda) nuclear receptors: Sixteen new members and a novel subfamily

Nuclear Receptor Genes: Evolution

“…This domain has maintained nearly 50% homology between all the superfamily members and over 90% homology between paralogous receptors (paralogous receptors are genes which have arisen by duplication within an ancestral species, for example, retinoic acid receptor alpha (RARA), retinoic acid receptor beta (RARB) and retinoic acid receptor gamma (RARG); Figure 2; also classified as NR1B1, NR1B2 and NR1B3 respectively; Nuclear Receptors Committee, 1999). As alluded to earlier, the genome of the Platyhelminthe Schistosoma mansoni contains three NRs that each contain two tandem DBDs (2DBD) (Sm2DBDa, Sm2DBDb and Sm2DBDg) (Wu et al, 2006). By database mining, 2DBD-containing NR genes were identified from the other flatworm species, Schmidtea mediterranea and Dugesia japonica, from mollusks (Lottia gigantean) and from arthropods (Daphnia pulex).…”

The evolution of the ligand/receptor couple: A long road from comparative endocrinology to comparative genomics

“…In fact the observation that an estrogen receptor orthologous gene is present in several mollusks (Thornton et al, 2003, Keay et al, 2006 as well as in cephalochordates (Paris et al, 2008b) shows that it is in fact much more ancient than expected and that the gene was lost independently in ecdysozoans and urochordates (Bertrand et al, 2004;Escriva et al, 2004). A very similar situation was found for the thyroid hormone receptor (Bertrand et al, 2004., Wu et al, 2006, Wu et al, 2007. It is now widely accepted that no conclusion can be reached on the presence or absence of a given gene in the common ancestor of all bilaterians if data from the three main lineages of metazoans (that is lophotrochozoans, ecdysozoans and deuterostomes) are not available.…”

Nuclear receptors in nematode development: Natural experiments made by a phylum

“…Exceptionally, NRs with two DBD domains are found in some species, e.g. in Platyhelminthes Schistosoma mansoni [5], Schmidtea mediterranea, Dugesia japonica, in the mollusk Lottia gigantea, and in the arthropod Daphnia pulex [6]. Another exception is represented by TLX, whose DBD differs from other NRs and forms a longer signature with additional cysteines [7].…”

“…2) that are divided into seven classes including (A) thyroid hormone receptors α and β (TRα, β) (NR1A1-2), (B) retinoic acid receptors α, β and γ (RARα, β, γ) (NR1B1-3), (C) peroxisome proliferators activated receptors α/β, δ and γ (PPARα/β, δ, γ) (NR1C1-3), (D) RevErbA α and β (NR1D1-2), (F) −ROR α, β and γ (NR1F1-3), (H) −LXR α and β, and FXR (NR1H3,2,4), (I) VDR, PXR, and CAR (NR1I1-3). Platyhelminths NR1 subfamily members that contain 2 DBDs are classified as NR1X [5,6].…”