Cloning of cDNAs encoding retinoic acid receptors RAR gamma 1, RAR gamma 2, and a new splicing variant, RAR gamma 3, from Aambystoma mexicanum and characterization of their expression during early development.
To analyze retinoic acid (RA) receptor (RAR) expression during early development in the urodele embryo, we have isolated cDNAs for four members of the axolotl (Ambystoma mexicanum) RAR family, namely RAR alpha (NR1B1), aRAR gamma 1 (NR1B3a), aRAR gamma 2 (NR1B3b), and a new splicing variant of aRAR gamma 2, aRAR gamma 3 (NR1B3c), which contains an insertion of five hydrophobic amino acids in the C-terminal region of the DNA binding domain. The temporal expression pattern of the RAR gamma isoforms was established by RT-PCR using total RNA from embryos of different stages. The expression of aRAR gamma 2 coincides with neurulation and is enhanced in the extremities of the embryo's anteroposterior axis. The aRAR gamma 3 is specifically expressed during gastrulation and early neurulation, whereas aRAR gamma 1 is expressed later during organogenesis. Global aRAR gamma 2 mRNA levels, as well as their spatio-temporal expression pattern in the neurula, were not affected by treatment with RA. These results show that several RARs are expressed in the axolotl embryo during early development, and reveal the existence of a new RAR gamma variant.
Wirtanen
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Centre de Recherche en Cancérologie de l'Université Laval, Québec, Québec, Canada.
Séguin
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D017398:Alternative Splicing; D000558:Ambystoma mexicanum; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000032:analysis; D018507:Gene Expression Regulation, Developmental; D008969:Molecular Sequence Data; D018168:Receptors, Retinoic Acid / Q000235:genetics*; D000072482:Retinoic Acid Receptor alpha; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D000097768:Retinoic Acid Receptor gamma
D018076:DNA, Complementary; D018168:Receptors, Retinoic Acid; D000072482:Retinoic Acid Receptor alpha; D000097768:Retinoic Acid Receptor gamma