Thyrotropin releasing hormone stimulates transient phosphorylation of the tissue-specific transcription factor, Pit-1

Paul W. Howard, Richard Maurer

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

The hypothalamic hormone, thyrotropin releasing hormone (TRH), stimulates prolactin (PRL) secretion and gene transcription in the GH3 pituitary cell line. Several studies have provided indirect evidence that phosphorylation of the pituitary-specific transcription factor Pit-1 may mediate TRH effects on PRL transcription. In the present study we have investigated the ability of TRH to alter the phosphorylation of Pit-1. In vivo 32P labeling experiments demonstrated that TRH stimulated a transient phosphorylation of Pit-1, reaching a maximum in 5 min and returning to basal levels within 30 min. Phosphopeptide mapping experiments demonstrated that TRH induced the transient phosphorylation of specific sites in Pit-1. TRH-stimulated phosphorylation of Pit-1 was blocked by treatments that deplete the cellular content of protein kinase C. Metabolic labeling and Western blot analysis demonstrate that TRH does not alter the total cellular content or nuclear concentration of Pit-1. TRH-mediated stimulation of a PRL promoter-luciferase fusion gene occurred under conditions that blocked the transient phosphorylation of Pit-1. These studies suggest that phosphorylation of Pit- 1 may not be necessary for TRH mediated enhancement of PRL gene transcription.

Original languageEnglish (US)
Pages (from-to)28662-28669
Number of pages8
JournalJournal of Biological Chemistry
Volume269
Issue number46
StatePublished - Nov 18 1994

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Transcription Factor Pit-1
Phosphorylation
Thyrotropin-Releasing Hormone
Tissue
Prolactin
Transcription
Genes
Labeling
Hypothalamic Hormones
Phosphopeptides
Gene Fusion
Luciferases
Protein Kinase C
Fusion reactions
Western Blotting
Experiments

ASJC Scopus subject areas

  • Biochemistry

Cite this

Thyrotropin releasing hormone stimulates transient phosphorylation of the tissue-specific transcription factor, Pit-1. / Howard, Paul W.; Maurer, Richard.

In: Journal of Biological Chemistry, Vol. 269, No. 46, 18.11.1994, p. 28662-28669.

Research output: Contribution to journalArticle

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