Molecular Endocrinology, Vol 6, 2059-2070, Copyright © 1992 by Endocrine Society

ARTICLES

Cyclic adenosine 3',5'-monophosphate activation of the rat prolactin promoter is restricted to the pituitary-specific cell type

CA Keech, SM Jackson, SK Siddiqui, KW Ocran and A Gutierrez-Hartmann
Department of Medicine and Biochemistry, University of Colorado Health Sciences Center, Denver 80262.

Pituitary lactotroph cell function and PRL gene expression are highly regulated by the cAMP-protein kinase-A (PKA) pathway. To further our understanding of the molecular mechanisms by which cAMP/PKA regulates rat (r) PRL promoter activity and to determine whether cAMP regulation is cell type specific, we 1) transected intact (-425), internal and 5'- deletion, and site-specific mutants of the rPRL promoter ligated to the firefly luciferase reporter gene into both pituitary and nonpituitary cell lines; and 2) assessed the role of the cAMP-cAMP response element- binding protein (CREB) pathway in GH4 rat pituitary cells. The data show that deleting the rPRL promoter from -425 to -116 did not abolish cAMP regulation, implying that proximal elements, such as the basal transcription element (-112/-80) or the pituitary-specific footprint (FP) I (-67/-45), mediate the cAMP response. However, nucleotide changes within FP I or FP II (-130/-120) did not alter the rPRL promoter response to 1 microM forskolin (FSK), despite the 77% and 26% reductions in basal rPRL promoter activity caused by these mutations, respectively. Furthermore, internal deletion of either the basal transcription element of FP I element also failed to affect cAMP regulation of the rPRL promoter, again despite the 90% and 93% reductions in basal promoter activity by these deletions, respectively. Since these internal deletion constructs otherwise contain rPRL promoter sequences from -425 to +73, including the up-stream pituitary- specific FPs III and IV, the data suggest that any one of these cell- specific elements is capable of imparting cAMP regulation to the proximal rPRL promoter. To directly test the implication that the cAMP response of the rPRL promoter is restricted to the pituitary-specific cell type, we took advantage of a 5'-deletion mutant truncated at position -116 and a FP II site-specific mutant, since constructs containing these rPRL promoters are active in nonpituitary cells. Despite the 6.6- and 18.5-fold stimulations over wild-type rPRL promoter activity in nonpituitary cells, respectively, these mutations remained completely unresponsive to FSK treatment. To document that the cAMP-CREB pathway was functional in GC/GH4 rat pituitary cells, CREB was affinity purified from GC rat pituitary cells, and DNase-I protection studies showed that it does not bind to the proximal rPRL promoter. Also, the human glycoprotein alpha-subunit promoter was induced 10-fold by FSK in GH4 rat pituitary cells.(ABSTRACT TRUNCATED AT 400 WORDS)

This article has been cited by other articles:

				M. Ishida, T. Mitsui, K. Yamakawa, N. Sugiyama, W. Takahashi, H. Shimura, T. Endo, T. Kobayashi, and J. Arita Involvement of cAMP response element-binding protein in the regulation of cell proliferation and the prolactin promoter of lactotrophs in primary culture Am J Physiol Endocrinol Metab, December 1, 2007; 293(6): E1529 - E1537. [Abstract] [Full Text] [PDF]

				R A Sporici, J S Hodskins, D M Locasto, L B Meszaros, A L Ferry, A M Weidner, C A Rinehart, J C Bailey, I M Mains, and S E Diamond Repression of the prolactin promoter: a functional consequence of the heterodimerization between Pit-1 and Pit-1 {beta} J. Mol. Endocrinol., October 1, 2005; 35(2): 317 - 331. [Abstract] [Full Text] [PDF]

				A L Ferry, D M Locasto, L B Meszaros, J C Bailey, M D Jonsen, K Brodsky, C J Hoon, A Gutierrez-Hartmann, and S E Diamond Pit-1{beta} reduces transcription and CREB-binding protein recruitment in a DNA context-dependent manner J. Endocrinol., April 1, 2005; 185(1): 173 - 185. [Abstract] [Full Text] [PDF]

				K. N. Farrow, A. P. Bradford, J. J. Tentler, and A. Gutierrez-Hartmann Structural and Functional Analysis of the Differential Effects of c-Jun and v-Jun on Prolactin Gene Expression Mol. Endocrinol., October 1, 2004; 18(10): 2479 - 2490. [Abstract] [Full Text] [PDF]

				D. L. Duval and A. Gutierrez-Hartmann Editorial: PRL-Releasing Peptide Stimulation of PRL Gene Transcription--Enter AKT Endocrinology, January 1, 2002; 143(1): 11 - 12. [Full Text] [PDF]

				J. Hayakawa, M. Ohmichi, K. Tasaka, Y. Kanda, K. Adachi, Y. Nishio, K. Hisamoto, S. Mabuchi, S. Hinuma, and Y. Murata Regulation of the PRL Promoter by Akt through cAMP Response Element Binding Protein Endocrinology, January 1, 2002; 143(1): 13 - 22. [Abstract] [Full Text] [PDF]

				P. Kievit, J. D. Lauten, and R. A. Maurer Analysis of the Role of the Mitogen-Activated Protein Kinase in Mediating Cyclic-Adenosine 3',5'-Monophosphate Effects on Prolactin Promoter Activity Mol. Endocrinol., April 1, 2001; 15(4): 614 - 624. [Abstract] [Full Text]

				R. E. Schweppe and A. Gutierrez-Hartmann Pituitary Ets-1 and GABP bind to the growth factor regulatory sites of the rat prolactin promoter Nucleic Acids Res., March 1, 2001; 29(5): 1251 - 1260. [Abstract] [Full Text] [PDF]

				K. K. Jacob and F. M. Stanley CCAAT/Enhancer-Binding Protein {alpha} Is a Physiological Regulator of Prolactin Gene Expression Endocrinology, October 1, 1999; 140(10): 4542 - 4550. [Abstract] [Full Text]

				W. R. Duan, J. L. Shin, and J. L. Jameson Estradiol Suppresses Phosphorylation of Cyclic Adenosine 3',5'-Monophosphate Response Element Binding Protein (CREB) in the Pituitary: Evidence for Indirect Action via Gonadotropin-Releasing Hormone Mol. Endocrinol., August 1, 1999; 13(8): 1338 - 1352. [Abstract] [Full Text]

				S. E. Diamond, M. Chiono, and A. Gutierrez-Hartmann Reconstitution of the Protein Kinase A Response of the Rat Prolactin Promoter: Differential Effects of Distinct Pit-1 Isoforms and Functional Interaction with Oct-1 Mol. Endocrinol., February 1, 1999; 13(2): 228 - 238. [Abstract] [Full Text]

				K. Zanger, L. E. Cohen, K. Hashimoto, S. Radovick, and F. E. Wondisford A Novel Mechanism for Cyclic Adenosine 3',5'-Monophosphate Regulation of Gene Expression by CREB-Binding Protein Mol. Endocrinol., February 1, 1999; 13(2): 268 - 275. [Abstract] [Full Text]

				R. N. Day, J. Liu, V. Sundmark, M. Kawecki, D. Berry, and H. P. Elsholtz Selective Inhibition of Prolactin Gene Transcription by the ETS-2 Repressor Factor J. Biol. Chem., November 27, 1998; 273(48): 31909 - 31915. [Abstract] [Full Text] [PDF]

				K. N. Farrow, N. Manning, F. Schaufele, and A. Gutierrez-Hartmann The c-Jun delta -Domain Inhibits Neuroendocrine Promoter Activity in a DNA Sequence- and Pituitary-specific Manner J. Biol. Chem., July 19, 1996; 271(29): 17139 - 17146. [Abstract] [Full Text] [PDF]

				P. W. Howard and R. A. Maurer A Composite Ets/Pit-1 Binding Site in the Prolactin Gene Can Mediate Transcriptional Responses to Multiple Signal Transduction Pathways J. Biol. Chem., September 8, 1995; 270(36): 20930 - 20936. [Abstract] [Full Text] [PDF]