Regulation of two c-erbA messenger ribonucleic acids in rat GH3 cells by thyroid hormone.
There is recent evidence suggesting that c-erbA is the thyroid hormone nuclear receptor, and that there may be multiple c-erbA genes. We investigated the effect of T3 on two c-erbA mRNAs present in GH3 cells. A partial cDNA was isolated from rat GH3 cells which is nearly identical (99.6% nucleotide identity) to rat c-erbA alpha, except for a unique 3'-region corresponding to the carboxyl terminal region of the predicted protein sequence. This cDNA (c-erbA alpha-2), like rat c-erbA alpha, hybridizes to a 2.6 kilobase (kb) mRNA which is distinct from a 6.2 kb species that hybridizes to c-erbA beta. Since nuclear T3-binding is down-regulated by T3, we hypothesized that one or both c-erbA mRNAs might be regulated by T3. GH3 cells were treated with 10 nM T3 for up to 24 h, a manipulation known to decrease nuclear T3 binding by approximately 2-fold in GH cells. Both the 6.2 kb and 2.6 kb mRNA species decreased to nearly 50% of control values at 24 h. These data indicate that these two c-erbA mRNAs are regulated by T3 and suggest that the T3 effect on T3 binding-activity in GH cells may be mediated, in part, by down-regulation of c-erbA mRNA levels.
D000236:Adenoma / Q000032:analysis / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D004274:DNA, Recombinant; D005786:Gene Expression Regulation / Q000187:drug effects*; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D018774:Oncogene Proteins v-erbA; D010911:Pituitary Neoplasms / Q000032:analysis / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics*; D051381:Rats; D011988:Receptors, Thyroid Hormone / Q000235:genetics / Q000378:metabolism; D012191:Retroviridae Proteins / Q000235:genetics*; D014284:Triiodothyronine / Q000378:metabolism / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D004274:DNA, Recombinant; D018774:Oncogene Proteins v-erbA; D012333:RNA, Messenger; D011988:Receptors, Thyroid Hormone; D012191:Retroviridae Proteins; D014284:Triiodothyronine; D004247:DNA