Role of the Sp Family of Transcription Factors in the Ontogeny of Growth Hormone Receptor Gene Expression

Abstract

The growth hormone (GH) receptor is essential for the actions of growth hormone on postnatal growth and metabolism. GH receptor transcripts are characterized by the presence of disparate 5′-untranslated exons. Factors regulating the expression of the GC rich L2 transcript of the murine GH receptor gene have hitherto remained unidentified. To characterize the mechanisms regulating expression of the L2 transcript, primer extension and ribonuclease protection assays were used to identify transcription start sites in RNA from liver of adult mice. Transient transfection experiments revealed that 2.0 kilobase pairs of the L2 5′-flanking sequence exhibited promoter activity in BNL CL.2 (mouse liver) cells, CV-1 (monkey kidney) cells, and HRP.1 trophoblasts. Deletional analysis localized a major regulatory region to within 75 base pairs of the 5′ transcription start site. Sequence analysis revealed that the region contained consensus binding sites for the Sp family of transcription factors. Standard gel shift and supershift analysis using liver nuclear extracts established that Sp1 and Sp3 bound this regulatory element. Transfection of wild type but not mutant decoy oligonucleotides into BNL CL.2 cells decreased the activity of the L2 promoter. Overexpression of Sp1 and Sp3 protein in Drosophila Schneider cells established that Sp3 is more potent than Sp1 in transactivating the L2 promoter. Co-transfection experiments further established that Sp1 antagonizes the activity of Sp3 to transactivate the L2 promoter. Western blot analysis of liver nuclear extracts revealed that the levels of Sp3 increase significantly after birth, suggesting a role for the Sp family of transcription factors in controlling the fetal to postnatal increase in GH receptor gene expression. The growth hormone (GH) receptor is essential for the actions of growth hormone on postnatal growth and metabolism. GH receptor transcripts are characterized by the presence of disparate 5′-untranslated exons. Factors regulating the expression of the GC rich L2 transcript of the murine GH receptor gene have hitherto remained unidentified. To characterize the mechanisms regulating expression of the L2 transcript, primer extension and ribonuclease protection assays were used to identify transcription start sites in RNA from liver of adult mice. Transient transfection experiments revealed that 2.0 kilobase pairs of the L2 5′-flanking sequence exhibited promoter activity in BNL CL.2 (mouse liver) cells, CV-1 (monkey kidney) cells, and HRP.1 trophoblasts. Deletional analysis localized a major regulatory region to within 75 base pairs of the 5′ transcription start site. Sequence analysis revealed that the region contained consensus binding sites for the Sp family of transcription factors. Standard gel shift and supershift analysis using liver nuclear extracts established that Sp1 and Sp3 bound this regulatory element. Transfection of wild type but not mutant decoy oligonucleotides into BNL CL.2 cells decreased the activity of the L2 promoter. Overexpression of Sp1 and Sp3 protein in Drosophila Schneider cells established that Sp3 is more potent than Sp1 in transactivating the L2 promoter. Co-transfection experiments further established that Sp1 antagonizes the activity of Sp3 to transactivate the L2 promoter. Western blot analysis of liver nuclear extracts revealed that the levels of Sp3 increase significantly after birth, suggesting a role for the Sp family of transcription factors in controlling the fetal to postnatal increase in GH receptor gene expression. growth hormone GH receptor kilobase pair(s) base pair(s) 3-(cyclohexylamino)propanesulfonic acid electrophoretic mobility shift assay 1,4, piperazine-diethanesulfonic acid untranslated region Rous sarcoma virus Pituitary GH1 is essential for postnatal growth and regulation of metabolism of fat, carbohydrate, and protein in animals. At the tissue level these pleiotropic actions of GH result from the interaction of GH with the GH receptor. Hence, regulating the expression of and modulating the function of the GH receptor is critical for the action of GH in the intact animal. The promoter-regulatory regions of the murine (1Menon R.K. Cheng H. Singh M. Mol. Endocrinol. 1997; 11: 1291-1304Crossref PubMed Scopus (11) Google Scholar, 2Zou L. Menon R.K. Endocrinology. 1995; 136: 5236-5239Crossref PubMed Google Scholar, 3Schwartzbauer G. Yu J.H. Cheng H. Menon R.K. J. Biol. Chem. 1998; 273: 24760-24769Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar, 4Schwartzbauer G. Menon R.K. Mol. Genet. Metab. 1998; 63: 243-253Crossref PubMed Scopus (68) Google Scholar), ovine (5O'Mahoney J.V. Brandon M.R. Adams T.E. Mol. Cell. Endocrinol. 1994; 101: 129-139Crossref PubMed Scopus (54) Google Scholar, 6Adams T.E. Baker L. Fiddes R.J. Brandon M.R. Mol. Cell. Endocrinol. 1990; 73: 135-145Crossref PubMed Scopus (106) Google Scholar), bovine (7Jiang H. Okamura C.S. Lucy M.C. J. Biol. Chem. 1999; 274: 7893-7900Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar), and human (8Zou L. Burmeister L. Sperling M.A. Endocrinology. 1997; 138: 1771-1774Crossref PubMed Scopus (32) Google Scholar) GH receptor genes have been partially characterized. A feature that is common to the GH receptor transcripts from these different species is the heterogeneity in the 5′-untranslated region (9Edens A. Talamantes F. Endocr. Rev. 1998; 19: 559-582Crossref PubMed Scopus (125) Google Scholar). This heterogeneity in the 5′-UTR results from splicing of the various exon 1 fragments to a common splice site located 11 bp upstream of the initiating ATG. Whereas the number of 5′-untranslated exons varies among species, in all examples the location of the splice site from the initiating ATG is constant. In the human liver there are at with the common GH receptor (9Edens A. Talamantes F. Endocr. Rev. 1998; 19: 559-582Crossref PubMed Scopus (125) Google Scholar). The and of the 5′-untranslated exons in of the in expression of GH receptor and are of GH and are In the have been F. H. Biol. 1995; PubMed Scopus Google Scholar, Endocrinology. 1995; 136: PubMed Google Scholar). The of RNA the is in is more in than in and is Endocrinology. 1995; 136: PubMed Google Scholar). In the have been (5O'Mahoney J.V. Brandon M.R. Adams T.E. Mol. Cell. Endocrinol. 1994; 101: 129-139Crossref PubMed Scopus (54) Google Scholar, 6Adams T.E. Baker L. Fiddes R.J. Brandon M.R. Mol. Cell. Endocrinol. 1990; 73: 135-145Crossref PubMed Scopus (106) Google Scholar). is a transcript and is to the human exon a GC of and is to the human and In the and have been (7Jiang H. Okamura C.S. Lucy M.C. J. Biol. Chem. 1999; 274: 7893-7900Abstract Full Text Full Text PDF PubMed Scopus (53) Google Scholar). In the and have been characterized G. Menon R.K. Mol. Genet. Metab. 1998; 63: 243-253Crossref PubMed Scopus (68) Google Scholar). of the and L2 transcripts is in a and The receptor transcript is in liver G. Yu J.H. Cheng H. Menon R.K. J. Biol. Chem. 1998; 273: 24760-24769Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar, L. Talamantes F. Endocrinology. 1995; 136: PubMed Google Scholar). liver and and L2 L. Talamantes F. Endocrinology. 1995; 136: PubMed Google Scholar). In the are more than the factors regulating expression of the different is at to that for the and regulatory a sequence G. Menon R.K. Mol. Genet. Metab. 1998; 63: 243-253Crossref PubMed Scopus (68) Google Scholar). located upstream from the transcription start site of the transcript with the transcription in cells L. Menon R.K. Endocrinology. 1995; 136: 5236-5239Crossref PubMed Google Scholar). The to in the promoter is located 5′ to the transcription start and and the activity of the promoter interaction with G. Yu J.H. Cheng H. Menon R.K. J. Biol. Chem. 1998; 273: 24760-24769Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar). the of the protein in the liver a role for this in the expression of the G. Yu J.H. Cheng H. Menon R.K. J. Biol. Chem. 1998; 273: 24760-24769Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar). In to the transcript, there is a of and factors regulating expression of the L2 transcript of the murine GH receptor The the and of the promoter-regulatory region of the L2 transcript of the murine GH receptor In this that the location of the transcription start promoter activity in the 5′-flanking region of the L2 transcript of the murine GH receptor that the Sp family of expression of the L2 transcript, and to that in the levels of the Sp a role in of GH receptor gene expression in the The oligonucleotides were used in these experiments in the mutant are in oligonucleotides were by of oligonucleotides with the with of adult RNA with to a of the L2 transcript of the GH receptor The is by of upstream from the start site of the GH receptor J. Talamantes F. Mol. Endocrinol. PubMed Scopus Google Scholar). The primer using and with RNA in 1 and 1 The extension by the of of murine virus and to for at of the the were by gel The of the extension were by on the gel and by a To the transcription start site of the primer extension experiments were with RNA from cells and a primer to the sequence of the A the upstream region of the L2 transcript into the to established sequence from this and the that contained bp of exon to bp of the upstream of the transcription start site for the L2 protection assay with of RNA and RNA by transcription of the with RNA in the presence of The a that to the L2 transcript and a to a of exon of the GH receptor and is common to the and L2 at and with were to the with the were on a gel and by and using a of the of the for the number of in the extracts from liver were R.K. Singh M. L. J. Biol. Chem. 1995; PubMed Scopus Google Scholar). 1 and were in the used to the nuclear fragments used were by The with and of to 1 of nuclear 1 of Sp1 protein in a of 1 of bovine 1 and 1 at for were by at gel with The were and to with at experiments the of fragments to the In experiments nuclear extracts were with the of Sp1 Sp3 for at to the binding by the of F. A. PubMed Scopus Google Scholar) using the 2.0 the were to the sites the site of the were to established The sequence were using the sequence analysis gene were to various of the GH receptor 5′-flanking of the receptor 5′-flanking region were from the of of at the 5′-flanking region and bp into the L2 into the site in the of to of with by in the of and and were by using the of these were by the oligonucleotides and by the in the into using were the to and The used for tissue experiments were from BNL CL.2 cells were in essential and fetal with and cells were on to of using the the experiments decoy of oligonucleotides wild type site sequence were with of of the cells were with and with for to for of activity the were with and the cells were by the of of a the by at for at of the were for of and activity using a were in Transfection by of of the the in expression is by the Rous sarcoma promoter The results of the assay are in for transfection of the using the protein assay were by analysis of to than were Schneider Drosophila cells were in in with fetal The cells were to to a of to of transfection of using the transfection To the role of Sp1 and Sp3 in regulating the activity of the GH receptor of the the GH receptor promoter fragments were with of Sp1 Sp3 expression of a in transfection to of transfection The cells were to the for to and for assays for of and activity of nuclear protein from liver were for at in and The protein were a gel in and and were the were to by in for 1 The were at in and and with the protein using the to the were for different of and from the by with for at The used were extension using after to RNA from The extension of in major and of and in 1 To the transcription start sites in the 5′-untranslated ribonuclease protection assays were from the of to RNA from liver and with A and The major were and in 1 The to exon and the to the major transcription start site by the primer extension at bp upstream of the initiating ATG. of the in the revealed that in the liver RNA from 1 the L2 GH receptor for of the GH receptor the of the in the GH receptor In in liver RNA from of the in the in the L2 The sequence upstream of the transcription start site is to bp from transcription start with the transcription base H. A. 1998; Scopus Google Scholar) to consensus for a in the upstream region from the transcription start sites The role of the 5′-flanking region in the regulation of transcription of the GH receptor gene by to expression of the gene in a transfection A of the 5′-flanking region of the GH receptor bp of exon upstream of the gene contained in the expression This exhibited activity into BNL CL.2 liver cells In transfection the expression of using than the with the and to that with the that the promoter. extension experiments with RNA from the cells that the transcription start site by the L2 promoter to the major start site in RNA from liver tissue Hence, that the 5′-flanking region of the L2 transcript of the murine GH receptor gene promoter activity and that expression of the gene at a site to that used by the GH receptor gene in liver of transcription site in expression of the of a primer extension with primer to the sequence of the and of RNA from BNL CL.2 cells with The of the by and To regulating transcription of the GH receptor fragments of GH receptor and the expression of these in BNL CL.2 cells by transfection Whereas of bp not result in a in the expression of the of the bp in of promoter results that the sequence bp and bp upstream of the transcription start site is essential for activity of the GH receptor To type of the GH receptor for the L2 transcript, the of the various gene were in CV-1 (monkey kidney) and HRP.1 not The expression of these various to that in BNL CL.2 cells with the to region for in CV-1 cells there a increase in activity from to the presence of a regulatory in this results that the promoter regulating expression of the L2 transcript of the GH receptor is in a of a with the expression of the L2 transcript in L. Talamantes F. Endocrinology. 1995; 136: PubMed Google Scholar). the results with the CV-1 cells that promoter upstream in the 5′-flanking region of the L2 a role in the regulation of expression of the L2 GH receptor The of expression on of the region located and bp upstream of the transcription start site the presence of regulatory within this analysis of the sequence of this region the presence of a site within this region that the and protein binding activity by of nuclear from liver to in the of and To the sequence of these experiments were Whereas a of the of all with sequence not the binding at a these results that these are To the of the binding to this regulatory experiments with a consensus binding site for the Sp family of the of of with consensus binding site for Sp1 the of all of with in the site to the of the the of the sequence to Sp1 experiments with Sp1 to revealed that the sequence to Sp1 protein In to the binding of Sp1 protein to and to the consensus Sp1 binding sequence not results that the binding to binding to of the Sp1 family of of Sp1 protein to the site in the promoter of the L2 transcript of the murine GH receptor Sp1 consensus were in the of 1 and presence of Sp1 protein and adult liver nuclear extracts and and to and Sp1 consensus and and oligonucleotides at of and and is The and and the are of of Sp1 protein and Sp1 consensus The Sp1 gene family at but transcription To the of the binding to supershift assays with for different Sp The of for Sp3 in and liver nuclear extracts the mobility of and In experiments of for Sp1 in supershift of and the of the significantly than with the Sp3 In and not the mobility of and and of the Sp the mobility of the results the presence of and to a in the and with liver nuclear and the established that Sp1 and Sp3 the the role of these in regulating the activity of the L2 promoter. of the site within the in of activity in transfection assays the of the binding of the Sp factors to the element. The levels of Sp1 expression in the of to role in regulating the activity of a promoter element. Hence, the of using Drosophila Schneider cells that have been to of Sp1 and Sp3 In the cells, not activity with the of Sp3 in these cells in increase in the activity of This increase in activity to the of Sp3 into the cells with the with 1 of Sp3 expression In the to of activity in these cells not results that Sp3 the activity of the L2 of the GH receptor gene and that this is on the region and bp upstream of the transcription start site. the of of Sp1 protein on the activity of the GH receptor promoter in the In with the results with Sp3 by Sp1 significantly with the of with of Sp1 results that Sp1 is to the activity of the GH receptor promoter is potent that Sp3 in to this promoter. the levels of Sp1 protein not to the of of Sp on the activity of the experiments to the levels of Sp in BNL CL.2 cells and the of this on the activity of the L2 promoter. this by the decoy In this of a the for the transcription of is into the with the This decoy with the site in the promoter and result in a in the protein to to the promoter element. This of the levels of protein been used to the role of Sp1 F. F. Endocrinology. 1999; PubMed Scopus Google Scholar) and transcription factors and M. L. A. 1995; PubMed Scopus Google Scholar). in of oligonucleotides with the wild type sequence a consensus site in a in the activity of the This to the of the with a and in activity with and In oligonucleotides that not Sp1 consensus binding site with in the site of the sequence the consensus Sp1 to significantly the activity of the from these experiments that Sp1 and Sp3 the activity of the and this regulation is on the presence of the element. have that Sp1 and Sp3 with to activity at site J. Biol. Chem. 1997; Full Text Full Text PDF PubMed Scopus Google Scholar, G. M. G. J. 1994; PubMed Scopus Google Scholar, 1997; PubMed Scopus Google Scholar, J.H. J. Biol. Chem. 1999; 274: Full Text Full Text PDF PubMed Scopus Google Scholar). that Sp1 and Sp3 to and the activity of the in the 5′-flanking region of the murine GH receptor there is a interaction Sp1 and Sp3 at the site. this of Sp1 and a of Sp3 were into cells, and the activity of the in these results that Sp1 the activity of Sp3 in a The of the of Sp3 by Sp1 at of Sp1 and in a in the of Sp3 to of that with Sp3 is that this in the of Sp3 not to decreased expression of Sp3 to of Sp1 from these results that Sp1 antagonizes the of Sp3 to transactivate the GH receptor L2 promoter. The expression of the L2 transcript of the murine GH receptor gene significantly after To in the levels of Sp3 a role in this of GH receptor the levels of Sp3 expression in of fetal and adult by Western blot and in Western blot analysis of liver nuclear extracts from adult revealed that to the of Sp3 1997; PubMed Scopus Google Scholar). In to the adult liver nuclear the levels of Sp3 protein were in the fetal liver nuclear The in levels of Sp3 in the fetal liver and not of the nuclear in the fetal nuclear the of the nuclear protein not results were by supershift with in the binding of Sp1 but not that of Sp3 in fetal liver nuclear that the Sp1 to the electrophoretic mobility of a of the This result the binding of GC factors and the of these to is at the this of binding of Sp factors to the is in to with adult liver nuclear extracts binding of Sp3 to the more than the binding of Sp1 from these results that the levels of Sp3 increase in the liver after in the 5′-untranslated regions of the GH receptor transcripts is a feature common to the GH receptor gene from different species (9Edens A. Talamantes F. Endocr. Rev. 1998; 19: 559-582Crossref PubMed Scopus (125) Google Scholar). In the transcripts and L2 have been have on the factors regulating expression of the transcript of the GH receptor gene (1Menon R.K. Cheng H. Singh M. Mol. Endocrinol. 1997; 11: 1291-1304Crossref PubMed Scopus (11) Google Scholar, 2Zou L. Menon R.K. Endocrinology. 1995; 136: 5236-5239Crossref PubMed Google Scholar, 3Schwartzbauer G. Yu J.H. Cheng H. Menon R.K. J. Biol. Chem. 1998; 273: 24760-24769Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar, R.K. Singh M. L. J. Biol. Chem. 1995; PubMed Scopus Google Scholar). The to identify and and factors that expression of the L2 transcript of the murine GH receptor In this the location of the transcription start that the 5′-flanking region of the L2 transcript of the murine GH receptor gene promoter identify the that the Sp family of expression of the L2 transcript, and to that in the levels of the Sp a role in of GH receptor gene expression in the results using ribonuclease protection assay with a for the L2 that of the GH receptor in the liver The and in with the that is not in liver G. Yu J.H. Cheng H. Menon R.K. J. Biol. Chem. 1998; 273: 24760-24769Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar) the presence of hitherto results are in with of analysis of liver of that of the contained the L2 transcript not The of the contained that have to characterized. The of for the murine GH receptor gene been in a A. Talamantes F. of the Scholar). In to the transcript that is not and a R.K. Singh M. L. J. Biol. Chem. 1995; PubMed Scopus Google Scholar), the L2 transcript is and is of a In are to a for regulation by transcription factors. have been to to regulation by the Sp family of a transcription for gene is nuclear protein that the transcription of a of and genes L. J. Biol. 1997; PubMed Scopus Google Scholar). of this protein by the of a family of transcription factors and and L. J. Biol. 1997; PubMed Scopus Google Scholar). of the binding that and with and that are to of In GC with significantly than the of the Sp family is that the of Sp1 to with of the and the of Sp1 from the protein to transcription to the by in of the transcription This of Sp family of transcription factors to is in the of the L2 transcript of the GH receptor results of the analysis that the sequence and bp is essential for activity of the L2 promoter and the promoter. analysis of the sequence revealed the presence of a binding site for the Sp family of experiments established that the Sp consensus bound Sp1 protein and nuclear from adult the various Sp in supershift results that the Sp3 and to a Sp1 the not Whereas Sp1 and Sp3 are in various expression to to of the To the of binding to the the result of the of protein in liver nuclear for binding to the with nuclear In results to that with liver nuclear binding of Sp1 and Sp3 and not that of with nuclear extracts not suggesting that the Sp protein binding of the not by the of the nuclear extracts In were with and liver nuclear Whereas were to that Sp3 and Sp1 were in the the of the in the with the electrophoretic mobility The results of the experiments with Sp consensus sequence oligonucleotides that the binding of this is to that of the Sp family of protein is a protein of than Sp1 with binding to that of a protein the protein the with the element. The role of the in the of this protein have to the of this In Sp1 and function In Sp3 is a protein with that and transcription with the Sp3 function the promoter and the L. J. Biol. Chem. 1997; Full Text Full Text PDF PubMed Scopus Google Scholar). The of Sp3 is of Sp3 transcription the Sp1 Sp1 and Sp3 have region that a The Sp3 been to a acid region to the L. J. Biol. Chem. 1997; Full Text Full Text PDF PubMed Scopus Google Scholar, J. M. G. J. PubMed Scopus Google Scholar). In been that the Sp3 gene at by different transcription have revealed that the of and are in a of and these a role in Sp3 to the function of of transcription 1997; PubMed Scopus Google Scholar). results that Sp1 and Sp3 of the L2 promoter of the GH receptor there is of the L2 promoter to these with Sp3 a potent and Sp1 a Sp1 and Sp3 have been to with to the of protein with Sp3 the of Sp1 J. Biol. Chem. 1997; Full Text Full Text PDF PubMed Scopus Google Scholar, G. M. G. J. 1994; PubMed Scopus Google Scholar, 1997; PubMed Scopus Google Scholar, J.H. J. Biol. Chem. 1999; 274: Full Text Full Text PDF PubMed Scopus Google Scholar). results that Sp1 antagonizes the of Sp3 to transactivate the L2 promoter. In to for and are mechanisms that the of transcription factors on gene expression. Sp1 is a of L2 promoter expression in cells, is to the of Sp1 on Sp3 of the L2 promoter. that with of of Sp1 and Sp3 on the 1997; PubMed Scopus Google Scholar), G. M. G. J. 1994; PubMed Scopus Google Scholar), G. G. L. 1994; PubMed Scopus Google Scholar), and G. L. 1995; Google Scholar) the Sp1 of Sp3 of the L2 promoter is by for binding at the site of the L2 promoter. not the of a role in this interaction Sp1 and Sp3 The Sp are to protein and L. J. Biol. 1997; PubMed Scopus Google Scholar). The role of in regulating the actions of Sp on the GH receptor L2 promoter is not is to a major role in the of Sp factors to to the of activity by acid not the binding activity of the not GH receptor gene expression a with expression in the and significantly after G. Menon R.K. Mol. Genet. Metab. 1998; 63: 243-253Crossref PubMed Scopus (68) Google Scholar). The of GH receptor fetal with the in that growth for the in Scholar). The mechanisms controlling this expression of the GH receptor A from a in the promoter-regulatory region of the transcript of the murine GH receptor gene R.K. Singh M. L. J. Biol. Chem. 1995; PubMed Scopus Google Scholar). is that the expression of G. Yu J.H. Cheng H. Menon R.K. J. Biol. Chem. 1998; 273: 24760-24769Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar, L. Talamantes F. Endocrinology. 1995; 136: PubMed Google Scholar), is that this and factors G. Yu J.H. Cheng H. Menon R.K. J. Biol. Chem. 1998; 273: 24760-24769Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar) a role in the fetal to postnatal of expression of the GH receptor from the ribonuclease protection assays that of the transcripts in the adult liver the L2 This for factors regulating the expression of the L2 transcript to a role in the regulating the increase in expression of the GH receptor results that the L2 promoter of the GH receptor gene is by Sp3 and that levels of Sp3 in the liver increase significantly after these results with a Sp3 the increase of expression of the GH receptor gene role for Sp1 in the fetal to postnatal of GH receptor gene expression. is that levels of Sp1 are in fetal liver with the adult liver Mol. Biol. 11: PubMed Scopus Google Scholar). Whereas by Sp1 is a of the L2 results that Sp1 with Sp3 to the of Sp3 on the L2 promoter. the of Sp3 and Sp1 the from fetal to postnatal a role for these in regulating the fetal to postnatal increase in GH receptor gene expression In this and partially the promoter-regulatory region controlling expression of the L2 transcript of the murine GH receptor that the 5′-flanking region of the L2 transcript of the murine GH receptor gene promoter activity and the of the promoter for transcription of the L2 GH receptor identify and characterize a regulatory in the L2 promoter that with the Sp family of A role for the Sp family of in the of GH receptor gene expression in the liver is by the interaction of Sp1 and Sp3 at the L2 promoter and the of expression of Sp1 and Sp3 in fetal and adult the and by A. The of F. Talamantes and G. in the is