Absence of lutropin (LH) receptor mRNA in the rat thyroid: further evidence for specificity cross-over at the thyroid-stimulating hormone receptor level.
Chorionic gonadotropin (CG) and purified lutropin (LH) activate intact thyroid tissue and isolated thyroid cells. A recent report has suggested that the presence of aberrant LH/CG receptors in human and rat thyroid tissue may interact with gonadotropin thus explaining the mechanisms of thyroid cell stimulation. To detect putative thyroidal LH receptor mRNA, a segment of the transmembrane region containing domains 3 through 6 of the rat (r) LH receptor was targeted for amplification using the polymerase chain reaction (PCR). cDNA prepared from a rLH receptor-positive control tissue (testis) was efficiently amplified under stringent annealing conditions giving a 486 bp product as predicted. However, cDNAs from thyroidal tissue and from the thyroid-stimulating hormone (TSH)- and hCG-responsive 1B-6 subclone of Fisher rat thyroid cells (FRTL-5) yielded no detectable 486 bp product. A smaller (non-LH) fragment amplified to similar extents from both testis and thyroidal cDNAs provided a useful internal control for amplification. This allowed the conclusion that specificity cross-over between LH/CG and TSH occurs at the TSH receptor and that the LH/CG receptor gene is transcriptionally silent in rat thyroidal cells.
Department of Medicine, Mount Sinai School of Medicine, New York, NY 10029.
P N
PN
Graves
T F
TF
Davies
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002478:Cells, Cultured; D004247:DNA / Q000235:genetics; D008297:Male; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D009928:Organ Specificity; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics*; D051381:Rats; D011974:Receptors, LH / Q000032:analysis / Q000235:genetics*; D011989:Receptors, Thyrotropin / Q000235:genetics*; D011994:Recombinant Proteins / Q000032:analysis; D015183:Restriction Mapping; D013737:Testis / Q000502:physiology; D013961:Thyroid Gland / Q000502:physiology*
D009838:Oligodeoxyribonucleotides; D012333:RNA, Messenger; D011974:Receptors, LH; D011989:Receptors, Thyrotropin; D011994:Recombinant Proteins; D004247:DNA