THYROTROPIN-RELEASING-HORMONE (TRH) GENE-EXPRESSION IN THE ANTERIOR-PITUITARY .1. PRESENCE OF PRO-TRH MESSENGER-RIBONUCLEIC-ACID AND PRO-TRH-DERIVED PEPTIDE IN A SUBPOPULATION OF SOMATOTROPHS

被引:33
作者
BRUHN, TO [1 ]
RONDEEL, JMM [1 ]
BOLDUC, TG [1 ]
JACKSON, IMD [1 ]
机构
[1] BROWN UNIV, RHODE ISL HOSP, DEPT MED, DIV ENDOCRINOL, PROVIDENCE, RI 02903 USA
关键词
D O I
10.1210/en.134.2.815
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
We have previously reported the presence of authentic pro-TRH-derived peptides in cultured anterior pituitary (AP) cells. The present studies were undertaken to determine whether pro-TRH mRNA could be demonstrated in the AP and to elucidate the cell type expressing pro-TRH. AP cells were cultured for up to 18 days, during which time the content of both TRH and prepro-TRH-(25-50) rose significantly (P<0.01). In contrast, the cellular contents of LH, FSH, TSH, and ACTH fell significantly (P<0.01), whereas that of GH increased by 45.9% (P<0.05). Northern blot analysis revealed that the levels of pro-TRH mRNA extracted from AP cells (18 days in culture) were similar to those in hypothalamic tissue from adult male rats, indicating a high relative abundance of this mRNA in the AP. In situ. hybridization experiments showed a dense accumulation of silver grains over a subpopulation of cultured AP cells. A combination of in situ hybridization for pro-TRH mRNA and immunocytochemistry for pituitary hormones revealed colocalization of pro-TRH mRNA and GH in a subpopulation of somatotrophs. No colocalization with LH-, TSH-, PRL-, or beta-endorphin-containing cells was observed. Immunocytochemistry at the electron microscopic level demonstrated that prepro-TRH-(25-50) was contained in a subpopulation of secretory granules in AP cells expressing this pro-TRH-derived sequence. These studies demonstrate that pro-TRH mRNA is present in cultured AP cells in high concentration and that the pro-TRH gene is expressed within a subpopulation of somatotrophs.
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页码:815 / 820
页数:6
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