Widespread distribution of immunoreactive thyroid hormone beta 2 receptor (TR beta 2) in the nuclei of extrapituitary rat tissues.
Messenger RNA for thyroid hormone receptor (TR) isoforms alpha 1 and beta 1 are widely distributed in rat tissues. Until recently, TR beta 2 mRNA was believed to be limited to the pituitary and the assumption was made that TR beta 2 protein was similarly restricted. We determined the distribution of TR beta 2 protein in selected adult and fetal rat tissues using three anti-TR beta 2 antisera directed to different amino acid sequences of the distinctive A/B domain of TR beta 2. The proportion of total nuclear binding capacity cleared by each antiserum was determined by saturation analysis. 10-20% of total binding capacity in adult brain, liver, kidney, and heart was immunoprecipitated by each antiserum. Use of specific antibodies to TR beta 1 and TR alpha 1 showed these isoforms accounted for the remainder of total T3 binding. Fetal liver and brain, however, contained only TR alpha 1. Immunohistochemical analysis of the adult tissues showed TR beta 2 present in nuclei. Reverse transcription polymerase chain reaction detected low levels of TR beta 2 mRNA in the adult tissues. We infer that TR beta 2 accounts for a significant fraction of TR in adult rat tissues despite the low levels of its mRNA.
Schwartz
H L
HL
Department of Medicine, University of Minnesota, Minneapolis 55455.
Lazar
M A
MA
Oppenheimer
J H
JH
D000818:Animals; D001483:Base Sequence; D002467:Cell Nucleus / Q000737:chemistry*; D005260:Female; D007074:Immunoglobulin G / Q000276:immunology; D008297:Male; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D011988:Receptors, Thyroid Hormone / Q000032:analysis* / Q000235:genetics / Q000276:immunology
D007074:Immunoglobulin G; D012333:RNA, Messenger; D011988:Receptors, Thyroid Hormone