Differential Role of Hepatocyte Nuclear Factor-1 in the Regulation of Glucose-6-phosphatase Catalytic Subunit Gene Transcription by cAMP in Liver- and Kidney-derived Cell Lines

Abstract

In liver and kidney, the terminal step in gluconeogenesis is catalyzed by glucose-6-phosphatase. To examine the effect of the cAMP signal transduction pathway on transcription of the gene encoding the catalytic subunit of glucose-6-phosphatase (G6Pase), G6Pase-chloramphenicol acetyltransferase (CAT) fusion genes were transiently transfected into either the liver-derived HepG2 or kidney-derived LLC-PK cell line. Co-transfection of an expression vector encoding the catalytic subunit of cAMP-dependent protein kinase (PKA) markedly stimulated G6Pase-CAT fusion gene expression, and mutational analysis of the G6Pase promoter revealed that multiple regions are required for this PKA response in both the HepG2 and LLC-PK cell lines. A sequence in the G6Pase promoter that resembles a cAMP response element is required for the full PKA response in both HepG2 and LLC-PK cells. However, in LLC-PK cells, but not in HepG2 cells, a hepatocyte nuclear factor-1 (HNF-1) binding site was critical for the full induction of G6Pase-CAT expression by PKA. Changing this HNF-1 motif to that for the yeast transcription factor GAL4 reduces the PKA response in LLC-PK cells to the same degree as deleting the HNF-1 site. However, co-transfection of this mutated construct with chimeric proteins comprising the GAL4-DNA binding domain ligated to the coding sequence for HNF-1α, HNF-1β, HNF-3, or HNF-4 completely restored the PKA response. Thus, we hypothesize that, in LLC-PK cells, HNF-1 is acting as an accessory factor to enhance PKA signaling through the cAMP response element by altering G6Pase promoter conformation or accessibility rather than specifically affecting some component of the PKA signal transduction pathway. In liver and kidney, the terminal step in gluconeogenesis is catalyzed by glucose-6-phosphatase. To examine the effect of the cAMP signal transduction pathway on transcription of the gene encoding the catalytic subunit of glucose-6-phosphatase (G6Pase), G6Pase-chloramphenicol acetyltransferase (CAT) fusion genes were transiently transfected into either the liver-derived HepG2 or kidney-derived LLC-PK cell line. Co-transfection of an expression vector encoding the catalytic subunit of cAMP-dependent protein kinase (PKA) markedly stimulated G6Pase-CAT fusion gene expression, and mutational analysis of the G6Pase promoter revealed that multiple regions are required for this PKA response in both the HepG2 and LLC-PK cell lines. A sequence in the G6Pase promoter that resembles a cAMP response element is required for the full PKA response in both HepG2 and LLC-PK cells. However, in LLC-PK cells, but not in HepG2 cells, a hepatocyte nuclear factor-1 (HNF-1) binding site was critical for the full induction of G6Pase-CAT expression by PKA. Changing this HNF-1 motif to that for the yeast transcription factor GAL4 reduces the PKA response in LLC-PK cells to the same degree as deleting the HNF-1 site. However, co-transfection of this mutated construct with chimeric proteins comprising the GAL4-DNA binding domain ligated to the coding sequence for HNF-1α, HNF-1β, HNF-3, or HNF-4 completely restored the PKA response. Thus, we hypothesize that, in LLC-PK cells, HNF-1 is acting as an accessory factor to enhance PKA signaling through the cAMP response element by altering G6Pase promoter conformation or accessibility rather than specifically affecting some component of the PKA signal transduction pathway. glucose-6-phosphatase catalytic subunit chloramphenicol acetyltransferase catalytic subunit of protein kinase A cAMP response element hepatocyte nuclear factor endoplasmic reticulum glycogen storage disease 8-bromoadenosine-3′:5′-monophosphate, cyclic 8-(4-chlorophenylthio)-adenosine-3′:5′-monophosphate, cyclic DNA binding domain cAMP response unit phosphoenolpyruvate carboxykinase polymerase chain reaction base pair(s) Glucose-6-phosphatase is a multicomponent system located in the endoplasmic reticulum (ER) that catalyzes the terminal step in gluconeogenesis and hepatic glycogenolysis (1.Nordlie R.C. Foster J.D. Lange A.J. Annu. Rev. Nutr. 1999; 19: 379-406Crossref PubMed Scopus (422) Google Scholar, 2.Mithieux G. Eur. J. Endocrinol. 1997; 136: 137-145Crossref PubMed Scopus (101) Google Scholar, 3.Foster J.D. Pederson B.A. Nordlie R.C. Proc. Soc. Exp. Biol. Med. 1997; 215: 314-332Crossref PubMed Scopus (98) Google Scholar, 4.Burchell A. Allan B.B. Hume Biol. PubMed Scopus Google site of the catalytic subunit of glucose-6-phosphatase is located the of the (1.Nordlie R.C. Foster J.D. Lange A.J. Annu. Rev. Nutr. 1999; 19: 379-406Crossref PubMed Scopus (422) Google Scholar, 2.Mithieux G. Eur. J. Endocrinol. 1997; 136: 137-145Crossref PubMed Scopus (101) Google Scholar, 3.Foster J.D. Pederson B.A. Nordlie R.C. Proc. Soc. Exp. Biol. Med. 1997; 215: 314-332Crossref PubMed Scopus (98) Google Scholar, 4.Burchell A. Allan B.B. Hume Biol. PubMed Scopus Google of the glucose-6-phosphatase system as proteins to both and the (1.Nordlie R.C. Foster J.D. Lange A.J. Annu. Rev. Nutr. 1999; 19: 379-406Crossref PubMed Scopus (422) Google Scholar, 2.Mithieux G. Eur. J. Endocrinol. 1997; 136: 137-145Crossref PubMed Scopus (101) Google Scholar, 3.Foster J.D. Pederson B.A. Nordlie R.C. Proc. Soc. Exp. Biol. Med. 1997; 215: 314-332Crossref PubMed Scopus (98) Google Scholar, 4.Burchell A. Allan B.B. Hume Biol. PubMed Scopus Google a an and a and (1.Nordlie R.C. Foster J.D. Lange A.J. Annu. Rev. Nutr. 1999; 19: 379-406Crossref PubMed Scopus (422) Google Scholar, 2.Mithieux G. Eur. J. Endocrinol. 1997; 136: 137-145Crossref PubMed Scopus (101) Google Scholar, 3.Foster J.D. Pederson B.A. Nordlie R.C. Proc. Soc. Exp. Biol. Med. 1997; 215: 314-332Crossref PubMed Scopus (98) Google Scholar, 4.Burchell A. Allan B.B. Hume Biol. PubMed Scopus Google Scholar, 1997; PubMed Scopus Google and by a protein A. J. PubMed Scopus Google Scholar, Nordlie R.C. 1999; PubMed Scopus Google Scholar, A. A. A. 1999; PubMed Scopus Google of component of the glucose-6-phosphatase system is the of glycogen storage disease are by the and and in or glucose-6-phosphatase 1997; PubMed Scopus Google Scholar, A. J. PubMed Scopus Google Scholar, Endocrinol. 1999; PubMed Scopus Google Scholar, J. Biol. 1999; PubMed Scopus Google is by in the and Endocrinol. 1999; PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, PubMed Scopus Google In are to as hepatic and hepatic and Endocrinol. 1999; PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, Eur. J. PubMed Scopus Google is by in and hepatic R.C. PubMed Scopus Google hepatic is a of an of rather than glycogenolysis A. PubMed Scopus Google that expression of as to the in hepatic PubMed Scopus Google Scholar, Rev. PubMed Scopus Google Scholar, Annu. Rev. PubMed Scopus Google with this G6Pase is in of Lange A.J. PubMed Google Scholar, PubMed Scopus Google Scholar, B.A. A. J. PubMed Scopus Google Scholar, J. Biol. PubMed Scopus Google Scholar, G. PubMed Scopus Google and Lange A.J. J. Biol. PubMed Scopus Google that a of G6Pase in liver in and is in the liver and the of the with in the of (1.Nordlie R.C. Foster J.D. Lange A.J. Annu. Rev. Nutr. 1999; 19: 379-406Crossref PubMed Scopus (422) Google Scholar, 2.Mithieux G. Eur. J. Endocrinol. 1997; 136: 137-145Crossref PubMed Scopus (101) Google Scholar, 3.Foster J.D. Pederson B.A. Nordlie R.C. Proc. Soc. Exp. Biol. Med. 1997; 215: 314-332Crossref PubMed Scopus (98) Google Scholar, 4.Burchell A. Allan B.B. Hume Biol. PubMed Scopus Google and are to hepatic G6Pase gene Thus, and Lange A.J. PubMed Google Scholar, J. Biol. PubMed Scopus Google Scholar, A.J. PubMed Scopus Google Scholar, 1997; PubMed Google Scholar, J. Biol. PubMed Scopus Google Scholar, Lange A.J. J. Biol. 1997; PubMed Scopus Google Scholar, J. G. PubMed Scopus Google and G6Pase gene expression Lange A.J. PubMed Google A.J. PubMed Scopus Google Scholar, J. J. 1997; PubMed Google Scholar, 1997; PubMed Scopus Google Scholar, Proc. A. PubMed Scopus Google Scholar, J. Biol. 1997; PubMed Scopus Google Scholar, Allan B.B. A. PubMed Scopus Google is to the of and Lange A.J. PubMed Google Scholar, J. Biol. PubMed Scopus Google Scholar, A.J. PubMed Scopus Google J. Biol. PubMed Scopus Google Scholar, J. G. PubMed Scopus Google Scholar, J. Biol. 1997; PubMed Scopus Google Scholar, Allan B.B. A. PubMed Scopus Google is the of G6Pase in the and G. PubMed Scopus Google Scholar, G. PubMed Scopus Google that G6Pase expression and both a a with in the of multiple cAMP G. PubMed Scopus Google In acting glucose-6-phosphatase PubMed Scopus Google and 1997; PubMed Scopus Google that a of the G6Pase promoter the sequence and was required for the effect of cAMP on G6Pase fusion gene expression in HepG2 cells. and Allan B.B. A. J. 1999; PubMed Scopus Google that in cells the G6Pase promoter sequence located and was critical for the of cAMP and was to a cAMP response element on the of this sequence to cAMP on the expression of a fusion gene Allan B.B. A. J. 1999; PubMed Scopus Google for this is in the we the effect of the cAMP signal transduction pathway on the of G6Pase gene transcription in both the liver-derived HepG2 and kidney-derived LLC-PK cell lines. that the of G6Pase fusion gene transcription by cAMP is than 1997; PubMed Scopus Google Scholar, Allan B.B. A. J. 1999; PubMed Scopus Google we that multiple promoter are required for the effect of cAMP on G6Pase fusion gene transcription in both HepG2 and LLC-PK cells. However, the of in the cell hepatocyte nuclear an in the induction of G6Pase fusion gene transcription by cAMP in LLC-PK cells, but not in HepG2 the the liver is to for of with the the A. J. 1999; PubMed Scopus Google However, some that the as as J. 1999; PubMed Scopus Google Scholar, J. J. 1999; PubMed Google that as and the to a in the of A. 1997; PubMed Scopus Google the of the in of is the In the we the of G6Pase gene transcription by the cAMP pathway in both the kidney-derived LLC-PK and the liver-derived HepG2 cell lines. that multiple are required for the full effect of cAMP on G6Pase-CAT gene expression and of promoter is a response unit Annu. Rev. PubMed Scopus Google or in this a cAMP response unit of and 1997; PubMed Scopus Google and and Allan B.B. A. J. 1999; PubMed Scopus Google both the of in the cAMP response. for this is to the of the PKA co-transfection in rather than the of cAMP 1997; PubMed Scopus Google Scholar, Allan B.B. A. J. 1999; PubMed Scopus Google induction of G6Pase-CAT fusion gene expression by the PKA co-transfection is critical for the of a multiple component a is required for the full effect of cAMP on G6Pase gene transcription in both the HepG2 and LLC-PK cell is that the of the that this in the cell lines. In or of the HNF-1 site in the G6Pase promoter reduces G6Pase-CAT gene expression by in LLC-PK cells this same is in HepG2 cells on G6Pase gene expression are to of and J. Biol. PubMed Google were the to the PKA co-transfection to a in a that of phosphoenolpyruvate carboxykinase that the and were required for fusion gene transcription in the HepG2 cell that were in Biol. Google HNF-1 to the site in the promoter but is not required for gene expression in HepG2 cells Biol. Google However, as with HNF-1 a in the induction of gene expression by cAMP in the J. PubMed Google by and A. J. Biol. PubMed Scopus Google Scholar, Biol. PubMed Scopus Google on the promoter that HNF-1 as an accessory factor to enhance the effect of the cAMP signal transduction pathway on gene expression rather than acting as a of PKA Thus, that an HNF-1 site in the promoter was required for the full cAMP response A. J. Biol. PubMed Scopus Google Scholar, Biol. PubMed Scopus Google that was of with and in both a and a a to the accessory factor of HNF-1 Biol. PubMed Scopus Google In and Biol. PubMed Scopus Google that was not by PKA in or in LLC-PK cells with HNF-1 a PKA response. to is by but is PKA site located the both and HNF-4 for HNF-1 and as accessory to enhance the effect of PKA this that HNF-1 is a in the G6Pase acting by altering DNA conformation or rather than affecting some component of the cAMP signal transduction pathway. HNF-1 as an accessory factor to enhance the of both Proc. A. PubMed Scopus Google and Endocrinol. 1997; PubMed Scopus Google on gene an of in glucose-6-phosphatase is either or to the with a of and Endocrinol. 1999; PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, Eur. J. PubMed Scopus Google in and Endocrinol. 1999; PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, Eur. J. PubMed Scopus Google with are with a by and PubMed Scopus Google and J. A. PubMed Scopus Google that are by a in with the of HNF-1 to G6Pase gene expression in response to the cAMP to that of G6Pase gene expression in to the with is that the of the kidney, the site of G6Pase gene expression, both and HNF-1β, the LLC-PK cell in this cell is the J.D. J. PubMed Scopus Google is that both and enhance the of the cAMP signal transduction pathway on G6Pase-CAT gene expression in the LLC-PK cell regions of the G6Pase we and for to for the effect of cAMP on G6Pase fusion gene transcription 1997; PubMed Scopus Google Scholar, Allan B.B. A. J. 1999; PubMed Scopus Google and are in the induction of G6Pase gene transcription by the cAMP pathway in LLC-PK cells However, in LLC-PK cells and not a the is to a effect of PKA on the expression of a fusion gene that in LLC-PK cells the cAMP pathway the the as an accessory factor binding site to enhance the cAMP effect through sequence of the to a but and 1997; PubMed Scopus Google that the of the G6Pase promoter with a binding site 1997; PubMed Scopus Google in that was into the motif to is that HNF-3, is in the 1997; Google is the factor that is the accessory element of as with to as an accessory factor to enhance the effect of on gene transcription Endocrinol. 1999; Google the in this is that of G6Pase gene transcription by the cAMP signal transduction pathway is through a in multiple promoter are required for the full In to cells, we that an HNF-1 binding site in the G6Pase promoter is critical for the of G6Pase gene transcription by the cAMP pathway in the LLC-PK cell line. we that regions of the G6Pase promoter as in cell are by the cAMP signal transduction pathway in LLC-PK cells as of is a in LLC-PK cells. Glucose-6-phosphatase is a multicomponent system located in the endoplasmic reticulum (ER) that catalyzes the terminal step in gluconeogenesis and hepatic glycogenolysis (1.Nordlie R.C. Foster J.D. Lange A.J. Annu. Rev. Nutr. 1999; 19: 379-406Crossref PubMed Scopus (422) Google Scholar, 2.Mithieux G. Eur. J. Endocrinol. 1997; 136: 137-145Crossref PubMed Scopus (101) Google Scholar, 3.Foster J.D. Pederson B.A. Nordlie R.C. Proc. Soc. Exp. Biol. Med. 1997; 215: 314-332Crossref PubMed Scopus (98) Google Scholar, 4.Burchell A. Allan B.B. Hume Biol. PubMed Scopus Google site of the catalytic subunit of glucose-6-phosphatase is located the of the (1.Nordlie R.C. Foster J.D. Lange A.J. Annu. Rev. Nutr. 1999; 19: 379-406Crossref PubMed Scopus (422) Google Scholar, 2.Mithieux G. Eur. J. Endocrinol. 1997; 136: 137-145Crossref PubMed Scopus (101) Google Scholar, 3.Foster J.D. Pederson B.A. Nordlie R.C. Proc. Soc. Exp. Biol. Med. 1997; 215: 314-332Crossref PubMed Scopus (98) Google Scholar, 4.Burchell A. Allan B.B. Hume Biol. PubMed Scopus Google of the glucose-6-phosphatase system as proteins to both and the (1.Nordlie R.C. Foster J.D. Lange A.J. Annu. Rev. Nutr. 1999; 19: 379-406Crossref PubMed Scopus (422) Google Scholar, 2.Mithieux G. Eur. J. Endocrinol. 1997; 136: 137-145Crossref PubMed Scopus (101) Google Scholar, 3.Foster J.D. Pederson B.A. Nordlie R.C. Proc. Soc. Exp. Biol. Med. 1997; 215: 314-332Crossref PubMed Scopus (98) Google Scholar, 4.Burchell A. Allan B.B. Hume Biol. PubMed Scopus Google a an and a and (1.Nordlie R.C. Foster J.D. Lange A.J. Annu. Rev. Nutr. 1999; 19: 379-406Crossref PubMed Scopus (422) Google Scholar, 2.Mithieux G. Eur. J. Endocrinol. 1997; 136: 137-145Crossref PubMed Scopus (101) Google Scholar, 3.Foster J.D. Pederson B.A. Nordlie R.C. Proc. Soc. Exp. Biol. Med. 1997; 215: 314-332Crossref PubMed Scopus (98) Google Scholar, 4.Burchell A. Allan B.B. Hume Biol. PubMed Scopus Google Scholar, 1997; PubMed Scopus Google and by a protein A. J. PubMed Scopus Google Scholar, Nordlie R.C. 1999; PubMed Scopus Google Scholar, A. A. A. 1999; PubMed Scopus Google of component of the glucose-6-phosphatase system is the of glycogen storage disease are by the and and in or glucose-6-phosphatase 1997; PubMed Scopus Google Scholar, A. J. PubMed Scopus Google Scholar, Endocrinol. 1999; PubMed Scopus Google Scholar, J. Biol. 1999; PubMed Scopus Google is by in the and Endocrinol. 1999; PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, PubMed Scopus Google In are to as hepatic and hepatic and Endocrinol. 1999; PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, Eur. J. PubMed Scopus Google is by in and hepatic R.C. PubMed Scopus Google hepatic is a of an of rather than glycogenolysis A. PubMed Scopus Google that expression of as to the in hepatic PubMed Scopus Google Scholar, Rev. PubMed Scopus Google Scholar, Annu. Rev. PubMed Scopus Google with this G6Pase is in of Lange A.J. PubMed Google Scholar, PubMed Scopus Google Scholar, B.A. A. J. PubMed Scopus Google Scholar, J. Biol. PubMed Scopus Google Scholar, G. PubMed Scopus Google and Lange A.J. J. Biol. PubMed Scopus Google that a of G6Pase in liver in and G6Pase is in the liver and the of the with in the of (1.Nordlie R.C. Foster J.D. Lange A.J. Annu. Rev. Nutr. 1999; 19: 379-406Crossref PubMed Scopus (422) Google Scholar, 2.Mithieux G. Eur. J. Endocrinol. 1997; 136: 137-145Crossref PubMed Scopus (101) Google Scholar, 3.Foster J.D. Pederson B.A. Nordlie R.C. Proc. Soc. Exp. Biol. Med. 1997; 215: 314-332Crossref PubMed Scopus (98) Google Scholar, 4.Burchell A. Allan B.B. Hume Biol. PubMed Scopus Google and are to hepatic G6Pase gene Thus, and Lange A.J. PubMed Google Scholar, J. Biol. PubMed Scopus Google Scholar, A.J. PubMed Scopus Google Scholar, 1997; PubMed Google Scholar, J. Biol. PubMed Scopus Google Scholar, Lange A.J. J. Biol. 1997; PubMed Scopus Google Scholar, J. G. PubMed Scopus Google and G6Pase gene expression Lange A.J. PubMed Google A.J. PubMed Scopus Google Scholar, J. J. 1997; PubMed Google Scholar, 1997; PubMed Scopus Google Scholar, Proc. A. PubMed Scopus Google Scholar, J. Biol. 1997; PubMed Scopus Google Scholar, Allan B.B. A. PubMed Scopus Google is to the of and Lange A.J. PubMed Google Scholar, J. Biol. PubMed Scopus Google Scholar, A.J. PubMed Scopus Google J. Biol. PubMed Scopus Google Scholar, J. G. PubMed Scopus Google Scholar, J. Biol. 1997; PubMed Scopus Google Scholar, Allan B.B. A. PubMed Scopus Google is the of G6Pase in the and G. PubMed Scopus Google Scholar, G. PubMed Scopus Google that G6Pase expression and both a a with in the of multiple cAMP G. PubMed Scopus Google In acting glucose-6-phosphatase PubMed Scopus Google and 1997; PubMed Scopus Google that a of the G6Pase promoter the sequence and was required for the effect of cAMP on G6Pase fusion gene expression in HepG2 cells. and Allan B.B. A. J. 1999; PubMed Scopus Google that in cells the G6Pase promoter sequence located and was critical for the of cAMP and was to a cAMP response element on the of this sequence to cAMP on the expression of a fusion gene Allan B.B. A. J. 1999; PubMed Scopus Google for this is in the we the effect of the cAMP signal transduction pathway on the of G6Pase gene transcription in both the liver-derived HepG2 and kidney-derived LLC-PK cell lines. that the of G6Pase fusion gene transcription by cAMP is than 1997; PubMed Scopus Google Scholar, Allan B.B. A. J. 1999; PubMed Scopus Google we that multiple promoter are required for the effect of cAMP on G6Pase fusion gene transcription in both HepG2 and LLC-PK cells. However, the of in the cell hepatocyte nuclear an in the induction of G6Pase fusion gene transcription by cAMP in LLC-PK cells, but not in HepG2 cells. the the liver is to for of with the the A. J. 1999; PubMed Scopus Google However, some that the as as J. 1999; PubMed Scopus Google Scholar, J. J. 1999; PubMed Google that as and the to a in the of A. 1997; PubMed Scopus Google the of the in of is the In the we the of G6Pase gene transcription by the cAMP pathway in both the kidney-derived LLC-PK and the liver-derived HepG2 cell lines. that multiple are required for the full effect of cAMP on G6Pase-CAT gene expression and of promoter is a response unit Annu. Rev. PubMed Scopus Google or in this a cAMP response unit of and 1997; PubMed Scopus Google and and Allan B.B. A. J. 1999; PubMed Scopus Google both the of in the cAMP response. for this is to the of the PKA co-transfection in rather than the of cAMP 1997; PubMed Scopus Google Scholar, Allan B.B. A. J. 1999; PubMed Scopus Google induction of G6Pase-CAT fusion gene expression by the PKA co-transfection is critical for the of a multiple component a is required for the full effect of cAMP on G6Pase gene transcription in both the HepG2 and LLC-PK cell is that the of the that this in the cell lines. In or of the HNF-1 site in the G6Pase promoter reduces G6Pase-CAT gene expression by in LLC-PK cells this same is in HepG2 cells on G6Pase gene expression are to of and J. Biol. PubMed Google were the to the PKA co-transfection to a in a that of phosphoenolpyruvate carboxykinase that the and were required for fusion gene transcription in the HepG2 cell that were in Biol. Google HNF-1 to the site in the promoter but is not required for gene expression in HepG2 cells Biol. Google However, as with HNF-1 a in the induction of gene expression by cAMP in the J. PubMed Google by and A. J. Biol. PubMed Scopus Google Scholar, Biol. PubMed Scopus Google on the promoter that HNF-1 as an accessory factor to enhance the effect of the cAMP signal transduction pathway on gene expression rather than acting as a of PKA Thus, that an HNF-1 site in the promoter was required for the full cAMP response A. J. Biol. PubMed Scopus Google Scholar, Biol. PubMed Scopus Google that was of with and in both a and a a to the accessory factor of HNF-1 Biol. PubMed Scopus Google In and Biol. PubMed Scopus Google that was not by PKA in or in LLC-PK cells with HNF-1 a PKA response. to is by but is PKA site located the both and HNF-4 for HNF-1 and as accessory to enhance the effect of PKA this that HNF-1 is a in the G6Pase acting by altering DNA conformation or rather than affecting some component of the cAMP signal transduction pathway. HNF-1 as an accessory factor to enhance the of both Proc. A. PubMed Scopus Google and Endocrinol. 1997; PubMed Scopus Google on gene an of in glucose-6-phosphatase is either or to the with a of and Endocrinol. 1999; PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, Eur. J. PubMed Scopus Google in and Endocrinol. 1999; PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, Eur. J. PubMed Scopus Google with are with a by and PubMed Scopus Google and J. A. PubMed Scopus Google that are by a in with the of HNF-1 to G6Pase gene expression in response to the cAMP to that of G6Pase gene expression in to the with is that the of the kidney, the site of G6Pase gene expression, both and HNF-1β, the LLC-PK cell in this cell is the J.D. J. PubMed Scopus Google is that both and enhance the of the cAMP signal transduction pathway on G6Pase-CAT gene expression in the LLC-PK cell regions of the G6Pase we and for to for the effect of cAMP on G6Pase fusion gene transcription 1997; PubMed Scopus Google Scholar, Allan B.B. A. J. 1999; PubMed Scopus Google and are in the induction of G6Pase gene transcription by the cAMP pathway in LLC-PK cells However, in LLC-PK cells and not a the is to a effect of PKA on the expression of a fusion gene that in LLC-PK cells the cAMP pathway the the as an accessory factor binding site to enhance the cAMP effect through sequence of the to a but and 1997; PubMed Scopus Google that the of the G6Pase promoter with a binding site 1997; PubMed Scopus Google in that was into the motif to is that HNF-3, is in the 1997; Google is the factor that is the accessory element of as with to as an accessory factor to enhance the effect of on gene transcription Endocrinol. 1999; Google the in this is that of G6Pase gene transcription by the cAMP signal transduction pathway is through a in multiple promoter are required for the full In to cells, we that an HNF-1 binding site in the G6Pase promoter is critical for the of G6Pase gene transcription by the cAMP pathway in the LLC-PK cell line. we that regions of the G6Pase promoter as in cell are by the cAMP signal transduction pathway in LLC-PK cells as of is a in LLC-PK cells. In the the liver is to for of with the the A. J. 1999; PubMed Scopus Google However, some that the as as J. 1999; PubMed Scopus Google Scholar, J. J. 1999; PubMed Google that as and the to a in the of A. 1997; PubMed Scopus Google the of the in of is the In the we the of G6Pase gene transcription by the cAMP pathway in both the kidney-derived LLC-PK and the liver-derived HepG2 cell lines. that multiple are required for the full effect of cAMP on G6Pase-CAT gene expression and of promoter is a response unit Annu. Rev. PubMed Scopus Google or in this a cAMP response unit of and 1997; PubMed Scopus Google and and Allan B.B. A. J. 1999; PubMed Scopus Google both the of in the cAMP response. for this is to the of the PKA co-transfection in rather than the of cAMP 1997; PubMed Scopus Google Scholar, Allan B.B. A. J. 1999; PubMed Scopus Google induction of G6Pase-CAT fusion gene expression by the PKA co-transfection is critical for the of a multiple component a is required for the full effect of cAMP on G6Pase gene transcription in both the HepG2 and LLC-PK cell is that the of the that this in the cell lines. In or of the HNF-1 site in the G6Pase promoter reduces G6Pase-CAT gene expression by in LLC-PK cells this same is in HepG2 cells on G6Pase gene expression are to of and J. Biol. PubMed Google were the to the PKA co-transfection to a in a that of phosphoenolpyruvate carboxykinase that the and were required for fusion gene transcription in the HepG2 cell that were in Biol. Google HNF-1 to the site in the promoter but is not required for gene expression in HepG2 cells Biol. Google However, as with HNF-1 a in the induction of gene expression by cAMP in the J. PubMed Google by and A. J. Biol. PubMed Scopus Google Scholar, Biol. PubMed Scopus Google on the promoter that HNF-1 as an accessory factor to enhance the effect of the cAMP signal transduction pathway on gene expression rather than acting as a of PKA Thus, that an HNF-1 site in the promoter was required for the full cAMP response A. J. Biol. PubMed Scopus Google Scholar, Biol. PubMed Scopus Google that was of with and in both a and a a to the accessory factor of HNF-1 Biol. PubMed Scopus Google In and Biol. PubMed Scopus Google that was not by PKA in or in LLC-PK cells with HNF-1 a PKA response. to is by but is PKA site located the both and HNF-4 for HNF-1 and as accessory to enhance the effect of PKA this that HNF-1 is a in the G6Pase acting by altering DNA conformation or rather than affecting some component of the cAMP signal transduction pathway. HNF-1 as an accessory factor to enhance the of both Proc. A. PubMed Scopus Google and Endocrinol. 1997; PubMed Scopus Google on gene an of in glucose-6-phosphatase is either or to the with a of and Endocrinol. 1999; PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, Eur. J. PubMed Scopus Google in and Endocrinol. 1999; PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, Eur. J. PubMed Scopus Google with are with a by and PubMed Scopus Google and J. A. PubMed Scopus Google that are by a in with the of HNF-1 to G6Pase gene expression in response to the cAMP to that of G6Pase gene expression in to the with is that the of the kidney, the site of G6Pase gene expression, both and HNF-1β, the LLC-PK cell in this cell is the J.D. J. PubMed Scopus Google is that both and enhance the of the cAMP signal transduction pathway on G6Pase-CAT gene expression in the LLC-PK cell regions of the G6Pase we and for to for the effect of cAMP on G6Pase fusion gene transcription 1997; PubMed Scopus Google Scholar, Allan B.B. A. J. 1999; PubMed Scopus Google and are in the induction of G6Pase gene transcription by the cAMP pathway in LLC-PK cells However, in LLC-PK cells and not a the is to a effect of PKA on the expression of a fusion gene that in LLC-PK cells the cAMP pathway the the as an accessory factor binding site to enhance the cAMP effect through sequence of the to a but and 1997; PubMed Scopus Google that the of the G6Pase promoter with a binding site 1997; PubMed Scopus Google in that was into the motif to is that HNF-3, is in the 1997; Google is the factor that is the accessory element of as with to as an accessory factor to enhance the effect of on gene transcription Endocrinol. 1999; Google the in this is that of G6Pase gene transcription by the cAMP signal transduction pathway is through a in multiple promoter are required for the full In to cells, we that an HNF-1 binding site in the G6Pase promoter is critical for the of G6Pase gene transcription by the cAMP pathway in the LLC-PK cell line. we that regions of the G6Pase promoter as in cell are by the cAMP signal transduction pathway in LLC-PK cells as of is a in LLC-PK cells. and for the and GAL4 and HNF-4 expression for analysis was in through the of the by of and