HNF-1alpha Gene Research Articles

Comprehensive Molecular Evaluation of HNF-1 Alpha, miR-27a, and miR-146 Gene Variants and Their Link with Predisposition and Progression in Type 2 Diabetes Patients.

Type 2 diabetes (T2D) is a metabolic condition induced by insulin resistance and pancreatic beta cell dysfunction. MicroRNAs (miRNAs) have biological significance because they regulate processes such as the molecular signaling pathways involved in the pathophysiology of diabetes mellitus. The hepatocyte nuclear factor-1 alpha (HNF-1 alpha) is a transcription factor found in hepatocytes and the pancreas. Mutations in the HNF-1 alpha gene were reportedly associated with maturity-onset diabetes of the young (MODY). The objective of the present study was to examine the associations between MiR-27a, MiR-146, and HNF-1 alpha single-nucleotide variations (SNVs) with T2D risk in the Saudi population. We evaluated the association of SNVs of miR-27a rs895819 A>G, 146a-rs2910164 C>G, and HNF-1 alpha rs1169288 G>T (I27L) with the risk of T2D in Saudi patients with the Amplification Refractory Mutation System PCR (ARMS-PCR). For the miR-27a SNVs, we used 115 cases (82 males, 33 females) and 117 matched healthy controls (HCs); for the Mir-146 SNVs, we used 103 cases (70 males, 33 females) and 108 matched HCs; and for the HNF-1 alpha, we employed 110 patients (80 males, 30 females) and 110 HCs. The blood biochemistry of the participants was essayed using commercial kits, and the methods of statistical analysis used were the Chi-square test, the Fisher exact test, and a multivariate analysis based on logistic regression, like the odds ratio (OD) and risk ratio (RR), with 95% confidence intervals (CIs). The MiR-27a rs895819 AG genotype was linked to increased T2D susceptibility, with OR = 2.01 and p-value = 0.011, and the miR-146 rs2910164 CG genotype and C allele were linked to an elevated risk of T2D, with OR = 2.75, p-value < 0.0016, OR = 1.77, and p-value = 0.004. The results also showed that the GT genotype and T allele of the HNF-1 alpha (rs1169288) G>T is linked to T2D, with OR = 2.18, p-value = 0.0061, and 1.77, p-value = 0.0059. The SNVs in miR-27a, miR-146, and HNF-1 alpha can be potential loci for T2D risk. The limitations of this study include the relatively small sample size and the fact that it was a cross-sectional study. To our knowledge, this is the first study to highlight the association between miR-27a, miR-146, and HNF-1 alpha SNVs and the risk of T2D in the Saudi population. Future large-scale case-control studies, as well as studies on the functions of the proteins and protein interaction studies for HNF-1 alpha, are required to verify our findings. Furthermore, these findings can be used for the identification and stratification of at-risk populations via genetic testing for T2D-prevention strategies.

A MOLECULAR STUDY OF HNF-1ALPHA GENE MUTATIONS IN MODY3 EGYPTIAN PATIENTS

Maturity onset diabetes of the young type 3 (MODY3) is a heterogeneous monogenic form of diabetes mellitus caused by mutations in the gene of ''hepatocyte nuclear factor-1alpha'' (HNF-1alpha) which result in poor insulin secretion in response to glucose. The aim of the present study is to detect, for the first time in Egypt, the mutations in the HNF-1alpha gene in the Egyptian patients, and to compare the results for the Egyptian patients with those in other regions. This study included eight Egyptian patients diagnosed with MODY3; their ages were between 12 and 17 years old. DNA extraction was carried out from the blood samples, which were collected from the patients. Then, the polymerase chain reaction (PCR) was applied, in each sample, on exons 6, 7, 8, 9 and 10 and on promoter 1 of MODY3 gene (HNF-1alpha). Exon 9 was not amplified in all the attempts. The direct sequence analyses of the promoter 1 and the preceding exons of HNF-1alpha gene were detected. The obtained results of the sequences were aligned with the normal ones which were obtained from NCBI reference sequence database with the accession number NM_000545.5. The results yielded single nucleotide polymorphism (SNP), of which are the missense and silent mutations. The maximum number of variants was that of SNPs. The results of the present study showed that about 20 different SNPs were detected in the promoter 1. The obtained results of the exons were: (i) one novel missense mutation c.1304T>A obtained in the exon 6, (ii) two SNPs c.1501+7G>A (IVS7+7G>A) and c.1769-24T>C (IVS9-24T>C) detected in intron 7 and intron 9, respectively, (iii) two silent mutations, c.1375C>T and c.1545G>A found in the exon 7 and the exon 8, respectively; and (iv) one missense mutation c.1460G>A detected in the exon 7. The variants ii, iii and iv were previously recorded in other populations. Thus, from these results we can suggest that the mutations in the HNF-1alpha gene can contribute to MODY3 disease in the Egyptian population.

Pancreatic lipid content is not associated with beta cell dysfunction in youth-onset type 2 diabetes.

To determine whether pancreatic lipid content is associated with type 2 diabetes and beta cell function in Indigenous and Caucasian adolescents. This was a cross-sectional study comparing (1)H-magnetic resonance spectroscopy-derived pancreatic triglyceride content in adolescents 13 to 18 years of age with type 2 diabetes (n=20) and body mass index-matched normoglycemic controls (n=34). Beta cell function was measured by the acute insulin response and disposition index derived from intravenous glucose tolerance tests. Pancreatic lipid content was not significantly different in youth with type 2 diabetes and their normoglycemic body mass index-matched peers (2.41 [95% CI: 0.63, 5.60] vs. 1.22 [0.08, 5.93]; p=0.27). Pancreatic triglyceride levels were not associated with measures of beta cell function in the cohort. In subgroup analyses, pancreatic lipid content was ∼4-fold higher in youth with type 2 diabetes who were carriers of the G319S mutation in the HNF-1alpha gene (7.45 [2.85, 26.8] vs. 2.20 [0.350, 3.30] % Fat to Water Ratio F/W; p=0.032). Pancreatic lipid content is not elevated in Indigenous or Caucasian youth with type 2 diabetes compared to normoglycemic youth, nor is it associated with beta cell function. The presence of the G319S mutation in the HNF-1alpha gene in Indigenous youth with type 2 diabetes is associated with higher pancreatic lipid content. Further research is needed to understand the mechanisms that explain beta cell failure in overweight youth with type 2 diabetes.

MALDI-TOF mass spectrometry screening of cholelithiasis risk markers in the gene of HNF1alpha

In recent years MALDI-TOF MS gained importance for high-throughput DNA analysis. In the present study this technique was used for the pathogenetic analysis of gallstone disease. The intestinal apical sodium-dependent bile acid transporter (ASBT) shows a genetic association with gallstone disease. ASBT has 3 binding sites in its 5'UTR for hepatocyte nuclear factor 1alpha (HNF1alpha). We hypothesized that genetic alterations in the HNF1alpha gene could influence ASBT expression. The gene HNF1alpha was sequenced in 46 Stuttgart random samples, composed of 16 controls and 30 gallstone patients. Subsequently, two independent cohorts (Stuttgart: 67 gallstones carriers, 109 controls, Leutkirch: 112 gallstone carriers, 99 controls) were screened by MALDI-TOF MS. The subjects were further divided by gender and weight. 24 known polymorphisms and two novel SNPs in the 3'UTR of HNF1alpha were detected (c.*220G>A and c.*1151G>A). After gender-specific sub-division of the pooled cohorts, 4 SNPs resulted in significant differences between male gallstone carriers and male controls (Stuttgart/Leutkirch: rs2255531 OR=2.78; p=0.006, rs1169288 OR=2.13; p=0.032, rs7310409 OR=2.34; p=0.025 and rs1169294 OR=2.13; p=0.031). Two novel variants in the 3'UTR of HNF1alpha were detected and four SNPs of HNF1alpha show a significant association to cholelithiasis in male gallstone patients. This article is part of a Special Section entitled: Understanding genome regulation and genetic diversity by mass spectrometry.

Novel variants in the hepatocyte nuclear factor-1-alpha gene in MODY and early onset NIDDM: Evidence for a mutational hotspot in exon 5

The disorder, Maturity Onset of Diabetes of the young (MODY) is a monogenic form of Non-Insulin dependent Diabetes Mellitus (NIDDM), characterized by autosomal dominant mode of inheritance and onset is usually before 25 years of age. Clinical studies of subjects with the different forms of MODY indicate that each is associated with a different defect in the normal pattern of glucose stimulated insulin secretion. MODY can result from mutations in any one of the six different genes, one of which encodes the glycolytic enzyme Glucokinase, associated with MO-DY2 and the other five encode transcription factors HNF4-alpha associated with MODY 1, HNF1-alpha associated with MODY 3, IPF with MODY 4, HNF1-Beta with MODY 5 and NeuroD1 with MO-DY6. Studies related to mutations in the MODY genes have led to a better understanding of the genetic causes of the Beta cell dysfunction as genetic factors plays a great role in this disorder. Objective: To investigate the mutation pattern in the different transcription factor genes with special reference to HNF1-alpha which are highly penetrant with 63% mutation carriers manifesting clinical diabetes by the age of 25 years. Hence study of mutation pattern in this gene is essential in our population i.e. Eastern Indian population. Our study is focused on HNF1-alpha related to MODY 3, which is the most common one. Methods: In our study enzyme amplification (PCR) of the 10 target exons of the said gene with simultaneous mutation detection in them by PCR-SSCP (Polymerase chain reaction-single strand conformational polymorphism) reaction analysis method was attempted by screening of exon 1 - 10 with respect to normal healthy controls without Diabetes Mellitus. The nature of the specific mutations was also determined by sequencing. Result: It was observed that maximum number of variations exist in exon 5 of HNF1-alpha gene which may be referred to as “Mutational Hotspot” in our Eastern Indian population. Conclusions: Since maximum number of variations exists in exon 5 of the said gene, hence one can initially go for exon5 followed by other exons, while screening for pathogenic MODY 3 mutations in the responsible gene by PCR-SSCP method.

HNF4alpha Dysfunction as a Molecular Rational for Cyclosporine Induced Hypertension

Induction of tolerance against grafted organs is achieved by the immunosuppressive agent cyclosporine, a prominent member of the calcineurin inhibitors. Unfortunately, its lifetime use is associated with hypertension and nephrotoxicity. Several mechanism for cyclosporine induced hypertension have been proposed, i.e. activation of the sympathetic nervous system, endothelin-mediated systemic vasoconstriction, impaired vasodilatation secondary to reduction in prostaglandin and nitric oxide, altered cytosolic calcium translocation, and activation of the renin-angiotensin system (RAS). In this regard the molecular basis for undue RAS activation and an increased signaling of the vasoactive oligopeptide angiotensin II (AngII) remain elusive. Notably, angiotensinogen (AGT) is the precursor of AngII and transcriptional regulation of AGT is controlled by the hepatic nuclear factor HNF4alpha. To better understand the molecular events associated with cyclosporine induced hypertension, we investigated the effect of cyclosporine on HNF4alpha expression and activity and searched for novel HNF4alpha target genes among members of the RAS cascade. Using bioinformatic algorithm and EMSA bandshift assays we identified angiotensin II receptor type 1 (AGTR1), angiotensin I converting enzyme (ACE), and angiotensin I converting enzyme 2 (ACE2) as genes targeted by HNF4alpha. Notably, cyclosporine represses HNF4alpha gene and protein expression and its DNA-binding activity at consensus sequences to AGT, AGTR1, ACE, and ACE2. Consequently, the gene expression of AGT, AGTR1, and ACE2 was significantly reduced as evidenced by quantitative real-time RT-PCR. While RAS is composed of a sophisticated interplay between multiple factors we propose a decrease of ACE2 to enforce AngII signaling via AGTR1 to ultimately result in vasoconstriction and hypertension. Taken collectively we demonstrate cyclosporine to repress HNF4alpha activity through calcineurin inhibitor mediated inhibition of nuclear factor of activation of T-cells (NFAT) which in turn represses HNF4alpha that leads to a disturbed balance of RAS.

HNF1 alpha gene coding regions mutations screening, in a Caucasian population clinically characterized as MODY from Argentina

Introduction There are at least six subtypes of Maturity Onset Diabetes of the Young (MODY) with distinctive genetic causes. MODY 3 is caused by mutations in HNF1A gene, an insulin transcription factor, so mutations in this gene are associated with impaired insulin secretion. MODY 3 prevalence differs according to the population analyzed, but it is one of the most frequent subtypes. Therefore, our aims in this work were to find mutations present in the HNF1A gene and provide information on their prevalence. Material and methods Mutations screening was done in a group of 80 unrelated patients (average age 17.1 years) selected by clinical characterization of MODY, by SSCP electrophoresis followed by sequenciation. Results We found eight mutations, of which six were novel and four sequence variants, which were all novel. Therefore the prevalence of MODY 3 in this group was 10%. Compared clinical data between the non-MODY 3 patients and the MODY 3 diagnosed patients did not show any significant difference. Discussion Eight patients were diagnosed as MODY 3 and new data about the prevalence of that subtype is provided. Our results contribute to reveal novel mutations, providing new data about the prevalence of that subtype.

Developmental and Tissue-Specific Regulation of Hepatocyte Nuclear Factor 4-α (HNF4-α) Isoforms in Rodents

Hepatocyte nuclear factor 4-alpha (HNF4-alpha) regulates expression of a number of genes in several metabolic organs. The HNF4-alpha gene has two promoters and encodes at least nine isoforms through differential splicing. In mouse liver, transcription initiates at promoter 2 (P2) during fetal life, but switches to P1 at birth. Developmental and tissue-specific expression of HNF4-alpha in other organs is largely unknown. Here, we examined expression of P1- and P2-derived transcripts in a number of mouse and rat tissues. Both P1 and P2 were active in mouse fetal liver, but P2-derived isoforms were detected 50% more abundantly than P1 transcripts. Conversely, the adult mouse liver expressed significantly higher levels of P1- than P2-derived mRNA. In contrast, in the rat, P1 was used more predominantly in both fetal and adult liver. Exposure of fetal rats to the synthetic glucocorticoid dexamethasone caused suppression of P2 while enhancing hepatic expression of transcripts from P1. This was associated with increased expression of erythropoietin and phosphoenolpyruvate carboxykinase, which are key HNF4-alpha targets in the liver. Unlike liver, the kidney and stomach used promoters more selectively, so that only P1-derived isoforms were detected in fetal and adult kidneys in mice or rats, whereas the stomach in both species expressed P2-derived transcripts exclusively. No significant HNF4-alpha mRNA was detected in the spleen. These data reveal striking developmental and tissue-specific variation in expression of HNF4-alpha, and indicate that this can be influenced by environmental factors (such as exposure to glucocorticoid excess), with potential pathophysiological consequences.

Distinct Regulation of Hepatic Nuclear Factor 1α by NKX6.1 in Pancreatic Beta Cells

Hepatic nuclear factor 1alpha (HNF1alpha) is a key regulator of development and function in pancreatic beta cells and is specifically involved in regulation of glycolysis and glucose-stimulated insulin secretion. Abnormal expression of HNF1alpha leads to development of MODY3 (maturity-onset diabetes of the young 3). We report that NK6 homeodomain 1 (NKX6.1) binds to a cis-regulatory element in the HNF1alpha promoter and is a major regulator of this gene in beta cells. We identified an NKX6.1 recognition sequence in the distal region of the HNF1alpha promoter and demonstrated specific binding of NKX6.1 in beta cells by electrophoretic mobility shift and chromatin immunoprecipitation assays. Site-directed mutagenesis of the NKX6.1 core-binding sequence eliminated NKX6.1-mediated activation and substantially decreased activity of the HNF1alpha promoter in beta cells. Overexpression or small interfering RNA-mediated knockdown of the Nkx6.1 gene resulted in increased or diminished HNF1alpha gene expression, respectively, in beta cells. We conclude that NKX6.1 is a novel regulator of HNF1alpha in pancreatic beta cells. This novel regulatory mechanism for HNF1alpha in beta cells may provide new molecular targets for the diagnosis of MODY3.

Effects of catechin-rich green tea on gene expression of gluconeogenic enzymes in rat hepatoma H4IIE cells

Rat hepatoma H4IIE cells were stimulated with dexamethasone and dibutyryl cAMP to increase gene expressions of gluconeogenic enzymes, glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK). Inclusion of catechin-rich green tea beverage (GTB) in the culture medium reduced the up-regulation of these genes as well as that of hepatocyte nuclear factor 4 alpha (HNF4alpha) gene. GTB was fractionated into chloroform-soluble (Fraction I), ethyl acetatesoluble (Fraction II), methanol-soluble (Fraction III) and residual (Fraction IV) fractions. Fractions II and III containing catechins caused an attenuation of the up-regulated expression of these genes as well as the down-regulation of HNF4alpha gene expression. Fraction IV had a synergistic effect on the up-regulation by dexamethasone/dibutyryl cAMP of the PEPCK gene expression and upregulated HNF4alpha gene expression. These results suggest that GTB down-regulated the expression of the HNF4alpha gene to cause the down-regulated gene expression of gluconeogenic enzymes. One reason why GTB did not down-regulate hepatic PEPCK gene expression in previous animal experiments may be that the component(s) acting to up-regulate PEPCK gene expression was more effective in vivo than in cultured cells.

Loss of Hepatocyte-Nuclear-Factor-4α Affects Colonic Ion Transport and Causes Chronic Inflammation Resembling Inflammatory Bowel Disease in Mice

BackgroundHnf4α, an epithelial specific transcriptional regulator, is decreased in inflammatory bowel disease and protects against chemically-induced colitis in mice. However, the precise role of this factor in maintaining normal inflammatory homeostasis of the intestine remains unclear. The aim of this study was to evaluate the sole role of epithelial Hnf4α in the maintenance of gut inflammatory homeostasis in mice.Methodology/Principal FindingsWe show here that specific epithelial deletion of Hnf4α in mice causes spontaneous chronic intestinal inflammation leading to focal areas of crypt dropout, increased cytokines and chemokines secretion, immune cell infiltrates and crypt hyperplasia. A gene profiling analysis in diseased Hnf4α null colon confirms profound genetic changes in cell death and proliferative behaviour related to cancer. Among the genes involved in the immune protection through epithelial barrier function, we identify the ion transporter claudin-15 to be down-modulated early in the colon of Hnf4α mutants. This coincides with a significant decrease of mucosal ion transport but not of barrier permeability in young animals prior to the manifestation of the disease. We confirm that claudin-15 is a direct Hnf4α gene target in the intestinal epithelial context and is down-modulated in mouse experimental colitis and inflammatory bowel disease.ConclusionOur results highlight the critical role of Hnf4α to maintain intestinal inflammatory homeostasis during mouse adult life and uncover a novel function for Hnf4α in the regulation of claudin-15 expression. This establishes Hnf4α as a mediator of ion epithelial transport, an important process for the maintenance of gut inflammatory homeostasis.

HNF4alpha and HNF1alpha Dysfunction as a Molecular Rational for Cyclosporine Induced Posttransplantation Diabetes Mellitus

Posttransplantation diabetes mellitus (PTDM) is a frequent complication in immunosuppressive therapy. To better understand the molecular events associated with PTDM we investigated the effect of cyclosporine on expression and activity of hepatic nuclear factor (HNF)1alpha and 4alpha and on genes coding for glucose metabolism in cultures of the rat insulinoma cell line INS-1E, the human epithelial cell line Caco-2 and with Zucker diabetic fatty (ZDF) rats. In the pancreas of untreated but diabetic animals expression of HNF4alpha, insulin1, insulin2 and of phosphoenolpyruvate carboxykinase was significantly repressed. Furthermore, cyclosporine treatment of the insulinoma-1E cell line resulted in remarkable reduction in HNF4alpha protein and INS1 as well as INS2 gene expression, while transcript expression of HNF4alpha, apolipoprotein C2, glycerolkinase, pyruvatekinase and aldolase B was repressed in treated Caco-2 cells. Furthermore, with nuclear extracts of cyclosporine treated cell lines protein expression and DNA binding activity of hepatic nuclear factors was significantly repressed. As cyclosporine inhibits the calcineurin dependent dephosphorylation of nuclear factor of activated T-cells (NFAT) we also searched for binding sites for NFAT in the pancreas specific P2 promoter of HNF4alpha. Notably, we observed repressed NFAT binding to a novel DNA binding site in the P2 promoter of HNF4alpha. Thus, cyclosporine caused inhibition of DNA binding of two important regulators for insulin signaling, i.e. NFAT and HNF4alpha. We further investigated HNF4alpha transcript expression and observed >200-fold differences in abundance in n = 14 patients. Such variability in expression might help to identify individuals at risk for developing PTDM. We propose cyclosporine to repress HNF4alpha gene and protein expression, DNA-binding to targeted promoters and subsequent regulation of genes coding for glucose metabolism and of pancreatic beta-cell function.

Down-Regulation of Hepatic HNF4α Gene Expression during Hyperinsulinemia via SREBPs

Mutations in the coding region of hepatocyte nuclear factor 4alpha (HNF4alpha), and its upstream promoter (P2) that drives expression in the pancreas, are known to lead to maturity-onset diabetes of the young 1 (MODY1). HNF4alpha also controls gluconeogenesis and lipid metabolism in the liver, where the proximal promoter (P1) predominates. However, very little is known about the role of hepatic HNF4alpha in diabetes. Here, we examine the expression of hepatic HNF4alpha in two diabetic mouse models, db/db mice (type 2, insulin resistant) and streptozotocin-treated mice (type 1, insulin deficient). We found that the level of HNF4alpha protein and mRNA was decreased in the liver of db/db mice but increased in streptozotocin-treated mice. Because insulin increases the activity of sterol regulatory element-binding proteins (SREBP)-1c and -2, we also examined the effect of SREBPs on hepatic HNF4alpha gene expression and found that, like insulin, ectopic expression of SREBPs decreases the level of hepatic HNF4alpha protein and mRNA both in vitro in primary hepatocytes and in vivo in the liver of C57BL/6 mice. Finally, we use gel shift, chromatin immunoprecipitation, small interfering RNA, and reporter gene analysis to show that SREBP2 binds the human HNF4alpha P1 promoter and negatively regulates its expression. These data indicate that hyperinsulinemia down-regulates HNF4alpha in the liver through the up-regulation of SREBPs, thereby establishing a link between these two critical transcription factor pathways that regulate lipid and glucose metabolism in the liver. These findings also provide new insights into diabetes-associated complications such as fatty liver disease.

Diabetes de comienzo en la infancia tratada con sulfonilureas

MODY 3 type diabetes belongs to the group of monogenic diabetes and is caused by mutations in the gene for hepatocyte nuclear factor 1-alpha (HNF1-alpha). Although MODY 2 type diabetes is the most frequent form of MODY diabetes in childhood, type 3 is the most frequent in the general population. We report the case of a 12 year old child with basal and post-prandrial hyperglycaemia. No cardinal symptoms of type 1 diabetes mellitus were present. There are numerous cases of diabetes in his family. C-Peptide was 1.13 ng/ml and pancreatic autoimmunity markers were negative. HNF-1alpha gene mutation was found in the patient as well as in his father and sister. Treatment with glibenclamide was started at a dose of 2.5 mg/day in order to reduce the risk of microvascular disease, as this as high in MODY 3 type diabetes as in type 1 diabetes mellitus. Blood glucose returned to normal and glycosylated haemoglobin was maintained between 4.9 and 5.6 %. Side-effects were not observed except some mild hypoglycaemias.

The A98V Single Nucleotide Polymorphism (SNP) in Hepatic Nuclear Factor 1 α (HNF-1α) is Associated with Insulin Sensitivity and β-Cell Function

Mutations in the hepatic nuclear factor-1-alpha ( HNF-1alpha) gene is considered as a candidate for the aetiology of type 2 diabetes. The aims of the study was to determine whether two single nucleotide polymorphisms (SNPs) ile27-to-leu and ala98-to-val in the HNF-1alpha gene associate with diabetes, insulin sensitivity as well as beta-cell function. 1 479 subjects of a volunteer sample with increased risk of type 2 diabetes were investigated. They underwent a 75 g oral glucose tolerance test (OGTT) with measurements of plasma glucose, insulin and C-peptide at fasting and at 30, 60, 90 and 120 minutes after the glucose challenge. The HNF-1alpha SNPs, I27L and A98V were genotyped. Patients harbouring the V98 allele exhibited higher serum insulin and C-peptide levels. The heterozygote variant was also associated with decrease in beta-cell function but better insulin sensitivity. No significant differences of any clinical parameters were found for I27L gene variants. Significant associations between the heterozygote A98V genotype and clinical parameters of insulin metabolism were reported but no relationship with type 2 diabetes was obtained. This may be explained by a balancing negative effect on insulin secretion and concomitant positive effect on insulin resistance in Val allele carriers.

Differentiation therapy of hepatocellular carcinoma in mice with recombinant adenovirus carrying hepatocyte nuclear factor-4α gene

Previous studies have shown that hepatocyte nuclear factor-4alpha (HNF4alpha) is a central regulator of differentiated hepatocyte phenotype and forced expression of HNF4alpha could promote reversion of tumors toward a less invasive phenotype. However, the effect of HNF4alpha on cancer stem cells (CSCs) and the treatment of hepatocellular carcinoma (HCC) with HNF4alpha have not been reported. In this study, an adenovirus-mediated gene delivery system, which could efficiently transfer and express HNF4alpha, was generated to determine its effect on hepatoma cells (Hep3B and HepG2) in vitro and investigate the anti-tumor effect of HNF4alpha in mice. Our results demonstrated that forced re-expression of HNF4alpha induced the differentiation of hepatoma cells into hepatocytes, dramatically decreased "stemness" gene expression and the percentage of CD133(+) and CD90(+) cells, which are considered as cancer stem cells in HCC. Meanwhile, HNF4alpha reduced cell viability through inducing apparent apoptosis in Hep3B, while it induced cell cycle arrest and cellular senescence in HepG2. Moreover, infection of hepatoma cells by HNF4alpha abolished their tumorigenesis in mice. Most interestingly, systemic administration of adenovirus carrying the HNF4alpha gene protected mice from liver metastatic tumor formation, and intratumoral injection of HNF4alpha also displayed significant antitumor effects on transplanted tumor models. The striking suppression effect of HNF4alpha on tumorigenesis and tumor development is attained by inducing the differentiation of hepatoma cells--especially CSCs--into mature hepatocytes, suggesting that differentiation therapy with HNF4alpha may be an effective treatment for HCC patients. Our study also implies that differentiation therapy may present as one of the best strategies for cancer treatment through the induction of cell differentiation by key transcription factors.

Can complement factors 5 and 8 and transthyretin be used as biomarkers for MODY 1 (HNF4A‐MODY) and MODY 3 (HNF1A‐MODY)?

Genetic testing is needed for the formal diagnosis of maturity-onset diabetes of the young (MODY), but this is not widely available. If any MODY biomarkers were known, these could possibly be used as an alternative. Hepatocyte nuclear factor (HNF)-1alpha and HNF-4alpha regulate transcription of genes encoding complement 5 (C5), complement 8 (C8) and transthyretin (TTR), suggesting that these could be potential biomarkers for the disease. We therefore set out to determine whether serum concentrations of C5, C8 and TTR can be used as biomarkers for patients with HNF4A-MODY and HNF1A-MODY. The serum concentrations of C5, C8 and TTR were analysed in patients with mutations in the HNF-1alpha (n=29) and HNF-4alpha (N=13) genes. Type 2 diabetic (n = 14) and healthy subjects (n = 20), matched for body mass index (BMI), served as diabetic and non-diabetic control groups, respectively. Type 2 diabetic patients had markedly increased levels of C5 and C8 compared with healthy control subjects. Levels of C5 and C8 correlated with glycated haemoglobin (C5: r = 0.48, P = 0.019). After adjustment for BMI, glycated haemoglobin, age and gender, HNF4A-MODY and HNF1A patients had reduced levels of C5 and C8 compared with Type 2 diabetic patients (C5: P = 0.001; C8: P = 0.004). In addition, patients with HNF4A-MODY, but not those with HNF1A-MODY, had decreased TTR compared with diabetic patients (P = 0.038). Serum concentrations of C5 and C8 seem to distinguish HNF4A and HNF1A-MODY from other forms of diabetes. However, hyperglycaemia per se increases the serum concentrations, thereby attenuating their potential role as biomarkers for MODY.

Expression of HNF4α variants in pancreatic islets and Ins‐1 β cells

Hepatocyte nuclear factor (HNF4alpha) is a nuclear receptor essential for endodermal differentiation and cell functions in the adult pancreas, liver, and other tissues. Mutations in the HNF4A gene cause MODY1. Up to nine protein variants arise from two developmentally regulated promoters. Because some variants lack the N-terminal activation function 1 (AF-1) and/or C-terminal inhibitory F domain, defining their tissue-specific regulation and function is important for understanding pancreatic beta cell behaviour. Expression of HNF4alpha variants in islets, rat Ins-1 insulinoma cells, and human Hep3B hepatocellular carcinoma cells was assessed using a long-range reverse transcription-polymerase chain reaction (RT-PCR) strategy capable of recognizing each combination of mRNA termini. Protein expression was verified by immuno-blotting with terminus-specific antibodies and DNA-binding assays. Mouse islets and both cell lines express HNF4alpha9, which lacks both AF-1 and the F domain. Islets also expressed the HNF4alpha P1 promoter variants HNF4alpha1/alpha2, and Hep3B cells expressed HNF4alpha3. When ectopically expressed in COS-7 cells, HNF4alpha1, alpha3, alpha7, and alpha9 each stimulated an HNF4alpha-dependent promoter. Variants containing exon 1B (HNF4alpha4 - alpha6) were not detected. Lack of canonical splicing signals and species conservation argues against exon 1B usage. This is the first report of HNF4alpha9 expression in any tissue. Our findings extend our understanding of HNF4alpha gene transcription and function. This knowledge may be useful in efforts to recover or establish regulated insulin secretion.

Zinc Supplementation Enhances Hepatic Regeneration by Preserving Hepatocyte Nuclear Factor-4α in Mice Subjected to Long-Term Ethanol Administration

Alcoholic liver disease is associated with sustained liver damage and impaired regeneration, as well as significant zinc deficiency. This study was undertaken to examine whether dietary zinc supplementation could improve liver regeneration by increasing the expression of genes involved in hepatic cellular proliferation in a mouse model of alcoholic liver disease. Adult 129S6 mice fed an ethanol-containing liquid diet for 6 months developed alcoholic liver disease as measured by serum alanine transferase activity and histopathological changes. Zinc supplementation to ethanol-exposed mice enhanced liver regeneration as indicated by increased numbers of proliferation cell nuclear antigen (PCNA)-positive and bromodeoxyuridine (BrdU)-labeled hepatocytes. Zinc-enhanced liver regeneration was associated with an increase in hepatocyte nuclear factor-4alpha (HNF-4alpha), a liver-enriched, zinc-finger transcription factor. Studies using cultured HepG2 cells showed that zinc deficiency suppressed cell proliferation and cell proliferation-related proteins, including hepatocyte growth factor (HGF), insulin-like growth factor I (IGF-I), insulin-like growth factor binding protein 1 (IGFBP1), metallothionein (MT), and cyclin D1, as well as HNF-4alpha. HNF-4alpha gene silencing inhibited cell proliferation in association with decreased protein levels of IGF-I, IGFBP1, MT, and cyclin D1. The present study provides evidence that zinc supplementation enhances liver regeneration at least in part by HNF-4alpha through the up-regulation of cell proliferation-related proteins, suggesting that dietary zinc supplementation may have beneficial effects in alcoholic liver disease.

Acidocétose diabétique d’évolution fatale : serait-ce un MODY3 (maturity-onset diabetes of the young de type 3) ?

Ketoacidotic coma is one of the possible diabetes mellitus first symptoms. It results from complete or relative lack of insuline and is often associated with type 1 diabetes. The authors report a case of a 45-years old woman with inaugural diabetes of which atypical features have motivated the study of MODY gene (maturity-onset diabetes of the young). Gly574ser polymorphism in the HNF-1alpha gene was found, in homozygous state, and the question of the responsibility of this polymorphism in this diabete is asked.