Cloning of cDNAs encoding retinoic acid receptors RARγ1, RARγ2, and a new splicing variant, RARγ3, from Ambystoma mexicanum and characterization of their expression during early development

• Published in: Biochimica et biophysica acta. Gene structure and expression 2000-06, Vol.1492 (1), p.81-93
• Main Authors: Wirtanen, Liz, Séguin, Carl
• Format: Article
• Language: English
• Subjects: Axolotl; Developmental expression pattern; Embryogenesis; Nuclear receptor; Retinoic acid receptor; RT-PCR
• ISSN: 0167-4781; 1879-2634
• DOI: 10.1016/S0167-4781(00)00081-6

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 RARα (NR1B1), aRARγ1 (NR1B3a), aRARγ2 (NR1B3b), and a new splicing variant of aRARγ2, aRARγ3 (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 RARγ isoforms was established by RT-PCR using total RNA from embryos of different stages. The expression of aRARγ2 coincides with neurulation and is enhanced in the extremities of the embryo’s anteroposterior axis. The aRARγ3 is specifically expressed during gastrulation and early neurulation, whereas aRARγ1 is expressed later during organogenesis. Global aRARγ2 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 RARγ variant.