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Expression of a retinoic acid receptor (RAR)‐like protein in the embryonic and adult nervous system of a protostome species
Author(s) -
Carter Christopher J.,
Rand Christopher,
Mohammad Imtiaz,
Lepp Amanda,
Vesprini Nicholas,
Wiebe Olivia,
Carlone Robert,
Spencer Gaynor E.
Publication year - 2015
Publication title -
journal of experimental zoology part b: molecular and developmental evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.823
H-Index - 63
eISSN - 1552-5015
pISSN - 1552-5007
DOI - 10.1002/jez.b.22604
Subject(s) - biology , retinoic acid , vertebrate , microbiology and biotechnology , retinoic acid receptor , retinoid , retinoid x receptor gamma , lymnaea stagnalis , retinoid x receptor , retinoic acid inducible orphan g protein coupled receptor , receptor , nervous system , nuclear receptor , genetics , neuroscience , snail , transcription factor , cell culture , gene , ecology
The vitamin A metabolite, retinoic acid, is an important molecule in nervous system development and regeneration in vertebrates. Retinoic acid signaling in vertebrates is mediated by two classes of nuclear receptors, the retinoid X receptors (RXRs) and the retinoic acid receptors (RARs). Recently, evidence has emerged to suggest that many effects of retinoic acid are conserved between vertebrate and invertebrate nervous systems, even though the RARs were previously thought to be a vertebrate innovation and to not exist in non‐chordates. We have cloned a full‐length putative RAR from the CNS of the mollusc Lymnaea stagnalis ( Lym RAR). Immunoreactivity for the RAR protein was found in axons of adult neurons in the central nervous system and in growth cones of regenerating neurons in vitro. A vertebrate RAR antagonist blocked growth cone turning induced by exogenous all‐ trans retinoic acid, possibly suggesting a role for this receptor in axon guidance. We also provide immunostaining evidence for the presence of RAR protein in the developing, embryonic CNS, where it is also found in axonal processes. Using qPCR, we determined that Lym RAR mRNA is detectable in the early veliger stage embryo and that mRNA levels increase significantly during embryonic development. Putative disruption of retinoid signaling in Lymnaea embryos using vertebrate RAR antagonists resulted in abnormal eye and shell development and in some instances completely halted development, resembling the effects of all‐ trans retinoic acid. This study provides evidence for RAR functioning in a protostome species. J. Exp. Zool. (Mol. Dev. Evol.) 324B: 51–67, 2015 . © 2014 Wiley Periodicals, Inc.