Detection and localization of the thyroid hormone receptor beta mRNA in the immature olfactory receptor neurons of chum salmon.

ABSTRACT: Thyroid hormone (TH) plays an important role in regulating multiple cellular and metabolic processes, including cell proliferation, cell death, and energy metabolism, in various organs and tissues of vertebrates. It is generally accepted that anadromous Pacific salmon (Oncorhynchus spp.) imprint odorants from their natal stream during their seaward migration, and they then use olfaction to discriminate their natal stream during the spawning migration. Both serum TH levels and the specific binding values of TH in the salmon olfactory epithelium were markedly increased during the seaward migration. However, thyroid hormone receptor (TR) expression in the olfactory epithelium has not been confirmed in vertebrates. We investigated gene expression of TR isoforms in chum salmon (O. keta) by both molecular biological and histochemical techniques. Expression of TR? mRNA was detected in the olfactory epithelium by reverse transcriptase polymerase chain reaction (RT-PCR). Nucleotide sequencing demonstrated the existence of a remarkable homology between the RT-PCR product and part of the ligand-binding domain of other teleost TR? isoforms. By in situ hybridization using a digoxygenin-labeled salmon olfactory TR? cRNA probe, signals for salmon olfactory TR? mRNA were observed preferentially in the perinuclear regions of immature olfactory receptor neurons (ORNs), as protein gene product 9.5 (PGP9.5)-immunopositive ORNs. Our results provide the first detection of TR? gene expression in the olfactory epithelium, and suggested the possibility that TR? may be involved in cell maturation and/or cell differentiation of the ORNs in Pacific salmon.

SUBMITTER: Kudo H 

PROVIDER: S-EPMC6106697 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature