scholarly journals The G115S mutation associated with maturity-onset diabetes of the young impairs hepatocyte nuclear factor 4α activities and introduces a PKA phosphorylation site in its DNA-binding domain

2004 ◽  
Vol 383 (3) ◽  
pp. 573-580 ◽  
Author(s):  
Bénédicte OXOMBRE ◽  
Mostafa KOUACH ◽  
Ericka MOERMAN ◽  
Pierre FORMSTECHER ◽  
Bernard LAINE
Keyword(s):  
Transcription Factor ◽  
Dna Binding ◽  
Transcriptional Activity ◽  
Phosphorylation Site ◽  
Binding Domain ◽  
Nuclear Factor ◽  
Dna Binding Domain ◽  
Maturity Onset Diabetes ◽  
Hepatocyte Nuclear Factor ◽  
Hepatocyte Nuclear Factor 4Α

HNF4α (hepatocyte nuclear factor 4α) belongs to a complex transcription factor network that is crucial for the function of hepatocytes and pancreatic β-cells. In these cells, it activates the expression of a very large number of genes, including genes involved in the transport and metabolism of glucose and lipids. Mutations in the HNF4α gene correlate with MODY1 (maturity-onset diabetes of the young 1), a form of type II diabetes characterized by an impaired glucose-induced insulin secretion. The MODY1 G115S (Gly115→Ser) HNF4α mutation is located in the DNA-binding domain of this nuclear receptor. We show here that the G115S mutation failed to affect HNF4α-mediated transcription on apolipoprotein promoters in HepG2 cells. Conversely, in pancreatic β-cell lines, this mutation resulted in strong impairments of HNF4α transcriptional activity on the promoters of LPK (liver pyruvate kinase) and HNF1α, with this transcription factor playing a key role in endocrine pancreas. We show as well that the G115S mutation creates a PKA (protein kinase A) phosphorylation site, and that PKA-mediated phosphorylation results in a decreased transcriptional activity of the mutant. Moreover, the G115E (Gly115→Glu) mutation mimicking phosphorylation reduced HNF4α DNA-binding and transcriptional activities. Our results may account for the 100% penetrance of diabetes in human carriers of this mutation. In addition, they suggest that introduction of a phosphorylation site in the DNA-binding domain may represent a new mechanism by which a MODY1 mutation leads to loss of HNF4α function.

scholarly journals Maturity-Onset Diabetes of the Young Type 1 (MODY1)-Associated Mutations R154X and E276Q in Hepatocyte Nuclear Factor 4α (HNF4α) Gene Impair Recruitment of p300, a Key Transcriptional Coactivator

2001 ◽  
Vol 15 (7) ◽  
pp. 1200-1210 ◽  
Author(s):  
Jérôme Eeckhoute ◽  
Pierre Formstecher ◽  
Bernard Laine
Keyword(s):  
Transcription Factor ◽  
Transcriptional Activity ◽  
Cell Function ◽  
Nuclear Factor ◽  
Maturity Onset Diabetes ◽  
Hepatocyte Nuclear Factor ◽  
Β Cell ◽  
Β Cell Function ◽  
Hepatocyte Nuclear Factor 4Α

Abstract Hepatocyte nuclear factor 4α (HNF4α) is a nuclear receptor involved in glucose homeostasis and is required for normal β-cell function. Mutations in the HNF4α gene are associated with maturity-onset diabetes of the young type 1. E276Q and R154X mutations were previously shown to impair intrinsic transcriptional activity (without exogenously supplied coactivators) of HNF4α. Given that transcriptional partners of HNF4α modulate its intrinsic transcriptional activity and play crucial roles in HNF4α function, we investigated the effects of these mutations on potentiation of HNF4α activity by p300, a key coactivator for HNF4α. We show here that loss of HNF4α function by both mutations is increased through impaired physical interaction and functional cooperation between HNF4α and p300. Impairment of p300-mediated potentiation of HNF4α transcriptional activity is of particular importance for the E276Q mutant since its intrinsic transcriptional activity is moderately affected. Together with previous results obtained with chicken ovalbumin upstream promoter-transcription factor II, our results highlight that impairment of recruitment of transcriptional partners represents an important mechanism leading to abnormal HNF4α function resulting from the MODY1 E276Q mutation. The impaired potentiations of HNF4α activity were observed on the promoter of HNF1α, a transcription factor involved in a transcriptional network and required for β-cell function. Given its involvement in a regulatory signaling cascade, loss of HNF4α function may cause reduced β-cell function secondary to defective HNF1α expression. Our results also shed light on a better structure-function relationship of HNF4α and on p300 sequences involved in the interaction with HNF4α.

Transcriptional activity of the zinc finger protein NGFI-A is influenced by its interaction with a cellular factor

1993 ◽  
Vol 13 (11) ◽  
pp. 6858-6865
Author(s):  
M W Russo ◽  
C Matheny ◽  
J Milbrandt
Keyword(s):  
Transcription Factor ◽  
Dna Binding ◽  
Transcriptional Activity ◽  
Zinc Fingers ◽  
Fold Increase ◽  
Binding Domain ◽  
Dna Binding Domain ◽  
Activation Domains ◽  
Cellular Factor ◽  
Inhibitory Domain

NGFI-A is an immediate-early gene that encodes a transcription factor whose DNA-binding domain is composed of three zinc fingers. To define the domains responsible for its transcriptional activity, a mutational analysis was conducted with an NGFI-A molecule in which the zinc fingers were replaced by the GAL4 DNA-binding domain. In a cotransfection assay, four activation domains were found within NGFI-A. Three of the activation domains are similar to those characterized previously: one contains a large number of acidic residues, another is enriched in proline and glutamine residues, and another has some sequence homology to a domain found in Krox-20. The fourth bears no resemblance to previously described activation domains. NGFI-A also contains an inhibitory domain whose removal resulted in a 15-fold increase in NGFI-A activity. This increase in activity occurred in all mammalian cell types tested but not in Drosophila S2 cells. Competition experiments in which increasing amounts of the inhibitory domain were cotransfected along with NGFI-A demonstrated a dose-dependent increase in NGFI-A activity. A point mutation within the inhibitory domain of the competitor (I293F) abolished this property. When the analogous mutation was introduced into native NGFI-A, a 17-fold increase in activity was observed. The inhibitory effect therefore appears to be the result of an interaction between this domain and a titratable cellular factor which is weakened by this mutation. Downmodulation of transcription factor activity through interaction with a cellular factor has been observed in several other systems, including the regulation of transcription factor E2F by retinoblastoma protein, and in studies of c-Jun.

scholarly journals Promoter-Specific Repression of Hepatocyte Nuclear Factor (HNF)-1β and HNF-1α Transcriptional Activity by an HNF-1β Missense Mutant Associated with Type 5 Maturity-Onset Diabetes of the Young with Hepatic and Biliary Manifestations

2004 ◽  
Vol 89 (3) ◽  
pp. 1369-1378 ◽  
Author(s):  
Sachiko Kitanaka ◽  
Yuko Miki ◽  
Yasuhide Hayashi ◽  
Takashi Igarashi
Keyword(s):  
Functional Analysis ◽  
Dna Binding ◽  
Transcriptional Activity ◽  
Target Genes ◽  
Dominant Negative ◽  
Nuclear Factor ◽  
Maturity Onset Diabetes ◽  
Hepatocyte Nuclear Factor ◽  
Onset Diabetes ◽  
Repressive Effect

Abstract Mutations in the hepatocyte nuclear factor (HNF)-1β lead to type 5 maturity-onset diabetes of the young (MODY5). HNF-1β forms a homodimer or a heterodimer with HNF-1α and regulates various target genes. HNF-1β mutations are rare, and no functional analysis has been performed in conjunction with HNF-1α. HNF-1β is expressed in the liver and biliary system and controls liver-specific and bile acid-related genes. Moreover, liver-specific Hnf-1β knockout mice present with severe jaundice. However, no patients with HNF-1β mutations have biliary manifestations. In this report, we found a novel missense mutation in the HNF-1β gene in a patient with neonatal cholestasis and liver dysfunction together with the common features of MODY5. Functional analysis revealed that the mutant HNF-1β had diminished transcriptional activity by loss of the DNA binding activity. The mutant had a promoter-specific dominant-negative transcriptional effect on wild-type HNF-1β and inhibited its DNA binding. Moreover, the mutant had a promoter- and cell-specific transcriptional repressive effect on HNF-1α and a promoter-specific inhibitory effect on HNF-1α DNA binding. From these results, we considered that the different phenotype of patients with HNF-1β mutations might be caused by the different HNF-1β activity in conjunction with the different repression of HNF-1α activity in selected promoters and tissues.

scholarly journals Transcriptional activity of the zinc finger protein NGFI-A is influenced by its interaction with a cellular factor.

1993 ◽  
Vol 13 (11) ◽  
pp. 6858-6865 ◽  
Author(s):  
M W Russo ◽  
C Matheny ◽  
J Milbrandt
Keyword(s):  
Transcription Factor ◽  
Dna Binding ◽  
Transcriptional Activity ◽  
Zinc Fingers ◽  
Fold Increase ◽  
Binding Domain ◽  
Dna Binding Domain ◽  
Activation Domains ◽  
Cellular Factor ◽  
Inhibitory Domain

NGFI-A is an immediate-early gene that encodes a transcription factor whose DNA-binding domain is composed of three zinc fingers. To define the domains responsible for its transcriptional activity, a mutational analysis was conducted with an NGFI-A molecule in which the zinc fingers were replaced by the GAL4 DNA-binding domain. In a cotransfection assay, four activation domains were found within NGFI-A. Three of the activation domains are similar to those characterized previously: one contains a large number of acidic residues, another is enriched in proline and glutamine residues, and another has some sequence homology to a domain found in Krox-20. The fourth bears no resemblance to previously described activation domains. NGFI-A also contains an inhibitory domain whose removal resulted in a 15-fold increase in NGFI-A activity. This increase in activity occurred in all mammalian cell types tested but not in Drosophila S2 cells. Competition experiments in which increasing amounts of the inhibitory domain were cotransfected along with NGFI-A demonstrated a dose-dependent increase in NGFI-A activity. A point mutation within the inhibitory domain of the competitor (I293F) abolished this property. When the analogous mutation was introduced into native NGFI-A, a 17-fold increase in activity was observed. The inhibitory effect therefore appears to be the result of an interaction between this domain and a titratable cellular factor which is weakened by this mutation. Downmodulation of transcription factor activity through interaction with a cellular factor has been observed in several other systems, including the regulation of transcription factor E2F by retinoblastoma protein, and in studies of c-Jun.

Crystallization and Preliminary X-Ray Studies of the DNA-Binding Domain of Hepatocyte Nuclear Factor-6α Complexed with DNA

2006 ◽  
Vol 13 (5) ◽  
pp. 531-533 ◽  
Author(s):  
Daisuke Iyaguchi ◽  
Min Yao ◽  
Nobuhisa Watanabe ◽  
Jun Nishihira ◽  
Isao Tanaka
Keyword(s):  
Dna Binding ◽  
Binding Domain ◽  
Nuclear Factor ◽  
Dna Binding Domain ◽  
Hepatocyte Nuclear Factor ◽  
X Ray

scholarly journals Association between Hepatocyte Nuclear Factor 6 (HNF-6) and FoxA2 DNA Binding Domains Stimulates FoxA2 Transcriptional Activity but Inhibits HNF-6 DNA Binding

2003 ◽  
Vol 23 (2) ◽  
pp. 437-449 ◽  
Author(s):  
Francisco M. Rausa ◽  
Yongjun Tan ◽  
Robert H. Costa
Keyword(s):  
Transcription Factor ◽  
Dna Binding ◽  
Transcriptional Activation ◽  
Transcriptional Activity ◽  
Nuclear Factor ◽  
Hepatocyte Nuclear Factor ◽  
Binding Assays ◽  
Dna Binding Domains ◽  
Binding Domains ◽  
Coactivator Protein

ABSTRACT In previous studies we used transgenic mice or recombinant adenovirus infection to increase hepatic expression of forkhead box A2 (FoxA2, previously called hepatocyte nuclear factor 3β [HNF-3β]), which caused diminished hepatocyte glycogen levels and reduced expression of glucose homeostasis genes. Because this diminished expression of FoxA2 target genes was associated with reduced levels of the Cut-Homeodomain HNF-6 transcription factor, we conducted the present study to determine whether there is a functional interaction between HNF-6 and FoxA2. Human hepatoma (HepG2) cotransfection assays demonstrated that HNF-6 synergistically stimulated FoxA2 but not FoxA1 or FoxA3 transcriptional activity, and protein-binding assays showed that this protein interaction required the HNF-6 Cut-Homeodomain and FoxA2 winged-helix DNA binding domains. Furthermore, we show that the HNF-6 Cut-Homeodomain sequences were sufficient to synergistically stimulate FoxA2 transcriptional activation by recruiting the p300/CBP coactivator proteins. This was supported by the fact that FoxA2 transcriptional synergy with HNF-6 was dependent on retention of the HNF-6 Cut domain LXXLL sequence, which mediated recruitment of the p300/CBP proteins. Moreover, cotransfection and DNA binding assays demonstrated that increased FoxA2 levels caused a decrease in HNF-6 transcriptional activation of the glucose transporter 2 (Glut-2) promoter by interfering with the binding of HNF-6 to its target DNA sequence. These data suggest that at a FoxA-specific site, HNF-6 serves as a coactivator protein to enhance FoxA2 transcription, whereas at an HNF-6-specific site, FoxA2 represses HNF-6 transcription by inhibiting HNF-6 DNA binding activity. This is the first reported example of a liver-enriched transcription factor (HNF-6) functioning as a coactivator protein to potentiate the transcriptional activity of another liver factor, FoxA2.

NMR Structure of Transcription Factor Sp1 DNA Binding Domain†,‡

Biochemistry ◽  
2004 ◽  
Vol 43 (51) ◽  
pp. 16027-16035 ◽  
Author(s):  
Shinichiro Oka ◽  
Yasuhisa Shiraishi ◽  
Takuya Yoshida ◽  
Tadayasu Ohkubo ◽  
Yukio Sugiura ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Dna Binding ◽  
Binding Domain ◽  
Nmr Structure ◽  
Dna Binding Domain ◽  
Transcription Factor Sp1
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