Hepatic Nuclear Factor 4alpha Research Articles

Hepatic nuclear factor 4 alpha promotes the ferroptosis of lung adenocarcinoma via transcriptional activation of cytochrome P450 oxidoreductase.

Lung adenocarcinoma is one of the most prevalent cancers while ferroptosis is crucial for cancer therapies. This study aims to investigate the function and mechanism of hepatic nuclear factor 4 alpha (HNF4A) in lung adenocarcinomas' ferroptosis. HNF4A expression in ferroptotic A549 cells was detected. Then HNF4A was knocked down in A549 cells while overexpressed in H23 cells. Cells with changed HNF4A expression were tested for cytotoxicity and the level of cellular lipid peroxidation. The expression of cytochrome P450 oxidoreductase (POR) expression was examined after HNF4A was knocked down or overexpressed. Chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR) and dual-luciferase assays were performed to validate the regulation of HNF4A on POR. Finally, POR was restored in HNF4A-altered cells to check whether it restores the effect of HNF4A on ferroptosis. We found that HNF4A expression significantly decreased in the ferroptosis of A549 cells, and this change can be blocked by deferoxamine, an inhibitor of ferroptosis. Knockdown of HNF4A inhibited ferroptosis in A549 cells while overexpression of HNF4A promoted ferroptosis in H23 cells. We identified a key ferroptosis-related gene, POR serves as a potential target gene of HNF4A, whose expression was significantly changed in lung adenocarcinoma cells knocking down or overexpressing HNF4A. We demonstrated that HNF4A was bound to the POR's promoter to enhance POR expression, and identified the binding sites via ChIP-qPCR and luciferase assays. Restoration of POR expression blocked the promoting effect of HNF4A on ferroptosis in lung adenocarcinoma. HNF4A promotes POR expression through binding to the POR's promoter, and subsequently promotes the ferroptosis of lung adenocarcinoma.

Fruit and Vegetable Consumption Interacts With HNF1A Variants on the C-Reactive Protein.

Epidemiological studies have demonstrated the inverse association between the intake of fruits and vegetables and inflammation. However, the mechanisms by which inflammation-related genes interact with fruit and vegetable intake and the role of these combinations in inflammation remain unclear. Therefore, we assessed the effect of interactions between fruit and vegetable intake and the hepatic nuclear factor 1 alpha (HNF1A) genetic variants on the C-reactive protein (CRP) levels. Baseline data from the Ansan and Ansung Cohort Study of the Korean Genome and Epidemiology Study (KoGES) were used. A total of 7,634 participants (3,700 men and 3,934 women) were included in the analyses. Fruit and vegetable intake was assessed using semi-quantitative food frequency questionnaire data. Genotyping information for HNF1A was extracted from the Affymetrix Genome-Wide Human SNP array 5.0. Inflammation was determined after overnight fasting by measuring CRP levels using automated analyzers. Multivariable logistic regression was used to estimate the adjusted odds ratio (AOR) with a 95% confidence interval (CI). In the fully adjusted model, men and women with the GG genotype of HNF1A rs2393791 and high fruit intake had lower odds of elevated CRP levels compared to those with the AA genotype and low fruit intake (AOR 0.50, 95% CI 0.38–0.67; AOR 0.73, 95% CI 0.55–0.97, respectively). Men and women with the rs2393791 GG genotype and high vegetable intake had lower odds of having elevated CRP levels compared to those with the AA genotype and low fruit intake (AOR 0.57, 95% CI 0.43–0.75; AOR 0.65, 95% CI 0.49–0.86, respectively). Men and women with the GG genotype and high total fruit and vegetable intake had lower odds of having elevated CRP levels. These findings indicate that fruit and vegetable intake interacts with HNF1A genetic polymorphisms, consequently influencing the inflammation levels.

Hepatic adenomatosis in a young woman with non-familial maturity-onset diabetes of the young type 3

Hepatic adenomatosis (HA) is a rare condition in which multiple adenomas exist in an otherwise healthy liver. The most common subtype (H-HA) is associated with bi-allelic, somatic hepatic nuclear factor 1-alpha (HNF1A) mutations. Maturity-onset diabetes of the young type 3 (MODY3) is most often seen in young individuals with heterozygous, germline mutations in HNF1A. In this report, we describe a 17-year-old woman with H-HA and non-familial MODY3.

111-OR: MODY3 Diagnosis from Deidentified Pancreatic Tissue Leads to Variant Identification in Living Relatives

As part of studies to understand human pancreatic islet pathophysiology in type 1 diabetes (T1D), we discovered normal β cell mass in a 33-year-old deceased organ donor with T1D for 17 years. Further analysis revealed the donor’s diabetes resulted from a causative variant in hepatic nuclear factor 1-alpha (HNF1A), associated with Maturity-onset Diabetes of the Young-3 (MODY3) (J Clin Invest 129:246, 2019), which can be treated with sulfonylureas. Review of the donor’s redacted medical chart suggested a family history of diabetes consistent with the known autosomal dominant pattern of inheritance of MODY3. With this clinically-actionable information, we desired to inform the donor’s family. However, de-identified samples are not considered “human subject” research by Institutional Review Boards (IRB), so the family’s identity was unknown with no defined pathway for communicating these findings. Working with a Human Tissue and Organ Research Resource and an organ procurement organization, we developed a new, IRB-approved communication path between those involved in tissue collection, scientific investigation, and the donor’s family and physician. This allowed targeted genetic testing of potentially affected family members, which revealed five living relatives of the donor who carried the HNF1A variant: three adults diagnosed with diabetes before the age of 25 currently treated with insulin and two children (ages 6 months and 3 years) who did not have clinical diabetes. Since none of the identified individuals were known to have MODY3, they will likely benefit from appropriate clinical care and surveillance. This experience demonstrates the need for the scientific community to develop guidelines to address handling, reporting, and use of research findings from de-identified tissue collected for research. Defining ethical avenues for donor family-investigator communications will benefit for both organ donor families and scientific research. Disclosure D. Sparling: None. R. Haliyur: None. J. Lindner: None. L. Weber: None. A. Ramirez: None. M. Brissova: None. A.C. Powers: None.

MON-LB120 MODY3 With Insulin Coding Gene Mutation and Craniofacial Microsomia: A Case Report

Background: Maturity onset diabetes in young 3 (MODY 3) is caused by mutation of the hepatic nuclear factor 1 alpha (HNF-1A) gene. Craniofacial macrosomia (CFM) is associated with an abnormal development of craniofacial structures during the embryonic period. Maternal diabetes and genetic predisposition have been associated with CFM1. There are rare reports about an association of MODY 3 and CFM. Clinical case: An 11-year-old male patient presented with right side CFM (mild mandibular hypoplasia, internal auditory canal absence, severe pinna hypoplasia, abnormal orbital size and location, O3.M0.E3.N0.S02) noted at 8 months of age. Preoperative examination revealed A1c at 10.9%. After short term intensive insulin therapy, he had standard bread meal test: fasting glucose 8.11 mmol/L, insulin 13.9 mIU/L (3-25), C-peptide 1.25 ng/ml (0.81-3.85); 1 hour glucose 10.05 mmol/L, insulin 27 mIU/L, C-peptide 2.42 ng/ml; 2 hour glucose 8.17 mmol/L, insulin 16.09 mIU/L, C-peptide 2.11 ng/ml. GADA, IAA and ICA were negative. The mother was diagnosed diabetes at age 27years, when the patient was 8-month-old, and received insulin therapy. The mother was blind by age 35years due to diabetic retinopathy and died of DKA at 38-years-old. The patient’s 16-year-old brother had left side CFM (O2.M1.E2.N0.S0) and his OGTT was normal. The father was diagnosed with impaired glucose tolerance. The family had whole genome sequencing by Sanger technique, and resequenced the mutation with side primers. The CGA to CAA mutation was present at the 686 loci of exon 3 of HNF1A gene in the patient and mother. The HNF1A exon 3 mutation of CGA to CAA resulted in the change of arginine to glutamine which by the HGMA database is recognized as a reported MODY3 gene mutation. There was a mutation of G to A in the 4 loci of exon 1 of the insulin coding region in chromosome 11 in both the patient and elder brother. Neither elder brother nor father had the CGA mutation of HNF1A. Conclusion: There has not been a previous report of a relationship between HNF1A and CFM. In this case, the elder brother had CFM without a HNF1A mutation which does not support a connection between CFM and HNF1A. The two brothers both had CFM and insulin coding gene mutations which would represent a new association not previously described. Further testing is needed to confirm a relationship between the two. Reference: 1. Chen Q, Zhao Y, Shen G, Dai J. Etiology and Pathogenesis of Hemifacial Microsomia. J Dent Res 2018; 97(12): 1297-305. 2. Gougoutas AJ, Singh DJ, Low DW, Bartlett SP. Hemifacial microsomia: clinical features and pictographic representations of the OMENS classification system. Plast Reconstr Surg 2007; 120(7): 112e-20e.

N-3 Fatty Acids Abrogate Dyslipidemia-Induced Changes in Bile Acid Uptake, Synthesis, and Transport in Young and Aged Dyslipidemic Rats.

In this study, the effect of n-3 fatty acids (FA) [α-linolenic acid (ALA) and eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA)] on the intestinal bile acid (BA) uptake, hepatic BA synthesis, and enterohepatic bile acid transporters (BAT) was assessed in young and aged dyslipidemic rats. Dyslipidemia was induced in young and aged rats by feeding a high-fat (HF) diet. Experimental groups received diets containing canola oil (HF + CNO) and fish oil (HF + FO) as a source of ALA and EPA + DHA, respectively. After 60 days of feeding, intestinal BA uptake and expression of apical sodium-dependent bile acid transporter (Asbt), organic solute transporter-alpha/beta (Osta/b) messenger RNA (mRNA), and hepatic expression of Na+ taurocholate cotransporting polypeptide (Ntcp), bile salt export pump (Bsep), cholesterol 7-α hydroxylase A1 (Cyp7a1), Farnesoid X receptor (Fxr), small heterodimer partner-1 (Shp), liver receptor homolog-1 (Lrh-1), and hepatic nuclear factor-4 alpha (Hnf4a) mRNA were measured. Hepatic 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase activity and total BA in serum, liver, and feces were assessed. The dyslipidemic HF group had: (1) increased intestinal BA uptake and Asbt and Osta/b mRNA expression, (2) increased BA in serum, (3) decreased hepatic expression of Ntcp, Bsep, and Cyp7a1 mRNA, (4) increased activity of HMG-CoA reductase, (5) increased hepatic expression of Fxr and Shp mRNA, (6) decreased hepatic expression of Lrh-1 and Hnf4a mRNA, and (7) decreased BA in feces, when compared to control, HF + CNO, and HF + FO groups. Immunostaining revealed increased expression of intestinal Asbt and hepatic Ntcp protein in the HF group when compared to control, HF + CNO, and HF + FO groups. n-3 FA abrogated dyslipidemia-induced changes in the intestinal uptake, hepatic synthesis, and enterohepatic transporters of BA in both young and aged rats. EPA + DHA was more effective than ALA in modulating dyslipidemia-induced changes.

Traditional clinical criteria outperform high-sensitivity C-reactive protein for the screening of hepatic nuclear factor 1 alpha maturity-onset diabetes of the young among young Asians with diabetes.

Young adults with diabetes in Asia represent a heterogeneous group. Using traditional clinical criteria to preselect individuals for testing for maturity-onset diabetes of the young (MODY) may exclude a large proportion from testing. High-sensitivity C-reactive protein (hs-CRP) has shown promise as a biomarker to differentiate hepatic nuclear factor 1 alpha (HNF1A)-MODY from type 2 diabetes. We aimed to compare the use of hs-CRP as a biomarker versus traditional criteria, to guide testing for HNF1A-MODY among a cohort of young adults with diabetes in Singapore. A total of 252 adults (age of onset ⩽45 years) and 20 children with diabetes were recruited. Using traditional criteria (family history of diabetes and onset of diabetes ⩽25 years) and an hs-CRP cut off of ⩽0.5 mg/l, 125 and 37 adults, respectively, were identified for HNF1A gene testing. All children underwent HNF1A gene testing. Five adults (5/143, 3.5%) with HNF1A-MODY were identified. There were no HNF1A gene mutations among the children. Traditional criteria correctly identified all five HNF1A-MODY individuals (5/125, 4%), while applying an hs-CRP level of ⩽0.5 mg/l selected just 1 of these 5 for HNF1A gene testing (1/37, 2.7%). None of those with a positive GAD antibody or undetectable C-peptide level had HNF1A-MODY. The use of hs-CRP to guide screening for HNF1A-MODY among Asian young adults with diabetes did not improve the diagnostic yield. Applying a combination of age of onset of diabetes under 25 years and a family history of diabetes alone could guide targeted HNF1A-MODY screening in Asians, with an expected yield of 4% diagnosed with HNF1A-MODY among those screened.

Diabetes consequences in the fetus liver of the non-obese diabetic mice

DM type 1 (T1D) incidence is increasing around 3% every year and represents risks for maternal and fetal health. The objective of this study was to explore the effects of diabetes on fetus liver cells in non-obese diabetic (NOD) mice. Hyperglycemic NOD (HNOD), normoglycemic NOD (NNOD) and BALB/c females were used for mating, and the fetus livers were collected at 19.5 gestation day (gd). HNOD group had reduced fetal weight (989.5±68.32 vs 1290±57.39 mg BALB/c, P<0.05) at 19.5 gd and higher glycemia (516.66±28.86 mg dl−1, P<0.001) at both 0.5 gd and 19.5 gd compared to other groups. The protein expression of albumin (ALB) was significantly reduced in HNOD group (0.9±0.2 vs 3.36±0.36 NNOD P<0.01, vs 14.1±0.49 BALB/c P<0.001). Reduced gene expression of ALB (1.34±0.12 vs 5.53±0.89 NNOD and 5.23±0.71 BALB/c, P<0.05), Hepatic Nuclear Factor-4 alpha (HNF-4α) (0.69±0.1 vs 3.66±0.36 NNOD, P<0.05) and miR-122 (0.27±0,10 vs 0.88±0.15 NNOD, P<0.05) was present in HNOD group. No difference for alpha-Fetoprotein (AFP) and gene expression was observed. In conclusion, our findings show the impacts of T1D on the expression of ALB, AFP, HNF-4α and miR-122 in fetus liver cells by using NNOD and HNOD mice.

MiRNA-Based Regulation of Hemostatic Factors through Hepatic Nuclear Factor-4 Alpha.

MiRNAs have been reported as CIS-acting elements of several hemostatic factors, however, their mechanism as TRANS-acting elements mediated by a transcription factor is little known and could have important effects. HNF4α has a direct and important role in the regulation of multiple hepatic coagulation genes. Previous in vitro studies have demonstrated that miR-24-3p and miR-34a-5p regulate HNF4A expression. Here we aimed to investigate the molecular mechanisms of miR-24 and miR-34a on coagulation through HNF4A. Transfections with miR-24 and miR-34a in HepG2 cells decreased not only HNF4A but also F10, F12, SERPINC1, PROS1, PROC, and PROZ transcripts levels. Positive and significant correlations were observed between levels of HNF4A and several hemostatic factors (F5, F8, F9, F11, F12, SERPINC1, PROC, and PROS1) in human liver samples (N = 104). However, miR-24 and miR-34a levels of the low (10th) and high (90th) percentiles of those liver samples were inversely correlated with HNF4A and almost all hemostatic factors expression levels. These outcomes suggest that miR-24 and miR-34a might be two indirect elements of regulation of several hemostatic factors. Additionally, variations in miRNA expression profiles could justify, at least in part, changes in HNF4A expression levels and its downstream targets of coagulation.

Abstract 461: Hepatic Nuclear Factor 4 Alpha as a Regulator of Alanine: Glyoxylate Aminotransferase 2 Expression and Systemic Levels of Endogenous Methylarginines

Introduction: Endogenous methylarginines have been proposed as markers and potentially mediators of cardiovascular diseases. Alanine:glyoxylate aminotransferase 2 (AGXT2) is the only enzyme capable of regulation of plasma levels of all three endogenous methylarginines. It has also been demonstrated that AGXT2 and its alternative substrate beta-aminoisobutyric acid (BAIB) can play an important modulatory role in lipid metabolism. Using bioinformatic analysis we identified a highly conserved putative binding site for the diabetes-associated transcription factor hepatic nuclear factor 4 alpha (HNF4A) in the mammalian AGXT2 promoter region. The aim of this study was to test the hypothesis that HNF4a is the major regulator of AGXT2 expression and activity. Methods and results: We introduced several point mutations in the putative HNF4A binding site and investigated their influence on activity of the murine Agxt2 promoter using luciferase reporter assay. The mutated constructs decreased the activity of the reporter gene by 75% as compared to the native promoter sequence. We showed direct binding of HNF4a to Agxt2 promoter using chromatin immunoprecipitation. We were able to demonstrate that siRNA-mediated knockdown of HNF4a leads to 50% reduction of Agxt2 expression in the murine hepatic cell line Hepa 1-6. In the in-vivo part of the project we showed that liver-specific Hnf4a knockout mice have a 90% reduction in liver Agxt2 mRNA levels, a 85% decrease in liver AGXT2 activity and significantly increased plasma levels of endogenous methylarginines and BAIB. Conclusions: In the current study we showed direct binding of HNF4a to the mammalian AGXT2 promoter region. We also demonstrated using in-vitro and in-vivo approaches that HNF4A is the major regulator of Agxt2 expression and has direct influence on systemic levels of endogenous methylarginines and BAIB. These findings suggest a novel link between NO-mediated impairment of vascular and renal function and lipid metabolism.

Lupin protein exerts cholesterol-lowering effects targeting PCSK9: From clinical evidences to elucidation of the in vitro molecular mechanism using HepG2 cells

PCSK9 inhibition is a novel approach for cholesterol reduction because of its crucial pathophysiological role in cholesterol metabolism. This work aimed at evaluating whether lupin protein/peptides may modulate PCSK9 production. Mild hypercholesterolaemic subjects consumed lupin protein or casein (30 g/day) for 4 weeks. The final level of circulating PCSK9, measured by ELISA, was reduced by 8.5% (p = 0.0454) versus baseline value, whereas it remained unchanged in the control group (casein). For investigating the mechanism of action, HepG2 cells were treated with peptic and tryptic peptides from lupin protein: reductions of PCSK9 production and secretion were observed as well as a decrease of hepatic nuclear factor 1-alpha (HNF1-alpha). For the first time, this work provides evidences that lupin protein/peptides may modulate the PCSK9 protein level production and secretion, contributing to explain the beneficial effects observed in animal and human studies and opening a completely new area of investigation on plant proteins.

The Metabolic Phenotype of Youth Onset Type 2 Diabetes: The Role of Pregestational Diabetes Exposure and the Hepatic Nuclear Factor 1Alpha G319S Polymorphism.

The influence of exposure to diabetes in utero and the HNF-1α G319S polymorphism on the metabolic phenotype of youth with T2DM at diagnosis is unknown. The objective of this study is to describe the metabolic phenotype at diagnosis of youth with T2DM: a) by exposure to gestational or pregestational diabetes and b) by HNF-1α G319S genotype. A cross-sectional retrospective chart review of youth with T2DM diagnosed between 2006 and 2011 seen at a single centre was performed. The primary variables of interest and selected clinical and biochemical characteristics at birth and at diagnosis of diabetes were extracted. Descriptive statistics and regression analyses were undertaken. One hundred eighty-four youth were included. Youth exposed to pregestational diabetes were younger at diagnosis (-1.26 years, p<0.001), had a shorter gestation (-1.73 weeks, p<0.001) and a lower waist z-score (-2.77, p<0.001) compared to those not exposed to diabetes in utero. Youth homozygous for the HNF-1α G319S polymorphism were younger (-1.77 years p<0.001), had a lower BMI z-score (-0.32, p=0.04), waist z-score (-1.91, p=0.04), HbA1c (-1.73%; 18.9 mmol/mol, p<0.01), triglycerides (-90.3 mg/dl; -1.02 mmol/L, p=0.04) and higher HDL-c (8.88 mg/dl; 0.23 mmol/L, p=0.001) compared to wild-type youth at diagnosis. Homozygote youth were less likely to have hypertension or acanthosis nigricans at diagnosis (OR 0.27, p=0.03; OR 0.32, p=0.04 respectively). Differences in the metabolic phenotype of subgroups of youth with T2DM suggest differences in the pathophysiology of diabetes. An understanding of specific phenotypes is necessary to plan and inform both prevention and intervention strategies.

Abstract MP74: Hnf1a Variant, Energy-reduced Diets, Weight Loss and Insulin Resistance: The Pounds Lost and Direct Trials

Background: Macronutrients regulate the gene expression of hepatic nuclear factor 1 alpha (HNF1A) which plays a key role in in the normal function of pancreatic beta cells and development of insulin resistance. Objective: We aimed to determine whether weight loss diets varying in macronutrients modulate the effect of HNF1A genetic variant on weight loss and improvement of insulin resistance. Methods: We analyzed the interaction between a diabetes-associated common variant in the HNF1A gene (rs7957197) and weight-loss diets on body weight and insulin resistance among 722 overweight/obese adults from a 2-year randomized weight-loss trial (POUNDS Lost). We then sought to validate the findings in an independent 2-year weight-loss trial (Dietary Intervention Randomized Controlled Trial; DIRECT), which involved 280 different overweight/obese adults. Results: In the POUNDS LOST, we found fat diet significantly modified the genetic effect of HNF1A such that greater decreases in body weight and waist were observed in participants with the T allele than others among high-fat diet group (P &lt;0.04 for both, P for interaction &lt;0.006, We observed borderline significant interactions for improvement of fasting insulin and insulin resistance (P for interaction=0.07 and 0.06, respectively). We found similar gene-fat interactions in the DIRECT. Conclusions: The consistent findings from two independent randomized intervention trials provide strong evidence that individuals with the HNF1A rs7957197 T allele may experience enhanced weight loss and improved insulin sensitivity as a result of hypocaloric, high-fat diets.

Variability in hepatic expression of organic anion transporter 7/SLC22A9, a novel pravastatin uptake transporter: impact of genetic and regulatory factors

Human organic anion transporter 7 (OAT7, SLC22A9) is a hepatic transport protein poorly characterized so far. We therefore sought to identify novel OAT7 substrates and factors contributing to variable hepatic OAT7 expression. Using OAT7-expressing cells, pravastatin was identified as a substrate. Hepatic SLC22A9/OAT7 mRNA and protein expression varied 28-fold and 15-fold, respectively, in 126 Caucasian liver samples. Twenty-four variants in SLC22A9 were genotyped, including three rare missense variants (rs377211288, rs61742518, rs146027075), which occurred only heterozygously. No variant significantly affected hepatic SLC22A9/OAT7 expression. The three missense variants, however, showed functional consequences when expressed in vitro. Hepatic nuclear factor 4-alpha (HNF4α) emerged as a major transcriptional regulator of SLC22A9 by a series of in silico and in vitro analyses. In conclusion, pravastatin is the first identified OAT7 drug substrate. Substantial inter-individual variability in hepatic OAT7 expression, majorly driven by HNF4α, may contribute to pravastatin drug disposition and might affect response.The Pharmacogenomics Journal advance online publication, 4 August 2015; doi:10.1038/tpj.2015.55.

Abstract 551: Deficiency of Hepatic Nuclear Factor 4 Alpha Results in Impaired Metabolism of Endogenous Methylarginines and Beta-aminoisobutiric Acid - A Novel Mechanism of Cardiovascular Complications in Patients With Type 2 Diabetes?

Introduction: Alanine-glyoxylate aminotransferase 2 (AGXT2) is the only known enzyme capable of degradation of all three endogenous methylarginines, which serve as markers and potentially mediators of cardiovascular disease. Recent studies also suggest that AGXT2 and its alternative substrate beta-aminoisobutyric acid (BAIB) play important role in lipid metabolism. The predicted core promoter region of mammalian AGXT2 promoter contains a highly conserved putative binding site for hepatic nuclear factor 4 alpha (HNF4A). Patients with severe deficiency in HNF4a develop maturity onset diabetes of young 1. Furthermore, polymorphisms of HNF4A are associated with increased risk of diabetes type 2. The aim of this study was to test the hypothesis that HNF4A is a major regulator of AGXT2 expression and activity. Methods and results: We demonstrated direct binding of HNF4A to the Agxt2 promoter region in hepatic cell line Hepa 1-6 using chromatin immunoprecipitation assays. Then we showed that mutations of the predicted HNF4A binding site in the Agxt2 core promoter result in up to 80% decrease in the promoter activity as assessed by luciferase reporter assays (p&lt;0.001). We used siRNA-mediated knockdown of HNF4A to determine whether this factor is required for basal Agxt2 expression in Hepa 1-6 cells. Knockdown of HNF4A led to almost 50% reduction in Agxt2 mRNA levels compared to controls (p&lt;0.01). We took advantage of the previously characterized inducible liver-specific Hnf4a knockout (KO) mice to determine whether HNF4A regulates Agxt2 expression in vivo and showed a 90% (p&lt;0.001) decrease in liver Agxt2 expression and a 85% (p&lt;0.01) decrease in liver AGXT2 activity towards methylarginines in Hnf4a KO mice compared with the wild-type littermates. Finaly, on a functional level, Hnf4a KO mice had significant amounts of BAIB present in plasma, whereas BAIB was not detectable in the plasma of the wild-type littermates. Conclusions: In our study we identified HNF4A as the major regulator of Agxt2 gene expression. This finding suggests that diabetic patients with HNF4A deficiency might have a unique mechanism for development of cardiovascular complication via AGXT2-dependent impairment of lipid metabolism and methylarginines-mediated vascular dysfunction.

Familial renal glycosuria and modifications of glucose renal excretion

Under physiological conditions, the kidneys contribute to glucose homoeostasis by producing glucose by gluconeogenesis and preventing glucose loss in urine. The glucose filtered by the glomeruli is completely reabsorbed in the renal proximal tubule. Renal gluconeogenesis produces 25% of the circulating glucose in the postabsorptive state, while the amount of glucose reabsorbed by the kidneys largely exceeds the quantity synthesized by kidney gluconeogenesis. Sodium-glucose cotransporter type 2 (SGLT-2) and glucose transporter 2 (GLUT2) carry out more than 90% of renal glucose uptake. In diabetes, both gluconeogenesis and renal glucose reabsorption are increased. The augmentation of glucose uptake in diabetes is due to the overexpression of renal glucose transporters SGLT-2 and GLUT2 in response to the increase in expression of transcription activator hepatic nuclear factor 1-alpha (HNF1α). The rise in glucose uptake contributes to hyperglycaemia and induces glomerular hyperfiltration by increasing sodium and water reabsorption in the proximal tubule that, in turn, modifies urine flux at the macula densa. SGLT-2 inhibitors improve glycaemic control and prevent renal hyperfiltration in diabetes. Loss of SGLT-2 transporter function is a benign state characterized by glycosuria. In contrast, mutations of other glucose transporters expressed in the kidney are responsible for severe disorders.

A new susceptibility locus for myocardial infarction, hypertension, type 2 diabetes mellitus, and dyslipidemia on chromosome 12q24.

We examined the role of hepatic nuclear factor-1 alpha (HNF1a) gene polymorphism on coronary artery disease (CAD) traits in 4631 Saudi angiographed individuals (2419 CAD versus 2212 controls) using TaqMan assay on ABI Prism 7900HT sequence detection system. Following adjustment for confounders, the rs2259820_CC (1.19 (1.01–1.42); P = 0.041), rs2464196_TT (1.19 (1.00–1.40); P = 0.045), and rs2259816_T (1.13 (1.01–1.26); P = 0.031) were associated with MI. The rs2259820_T (1.14 (1.03–1.26); P = 0.011) and rs2464196_C (1.12 (1.02–1.24); P = 0.024) were associated with type 2 diabetes mellitus (T2DM), while the rs2393791_T (1.14 (1.01–1.28); P = 0.032), rs7310409_G (1.16 (1.03–1.30); P = 0.013), and rs2464196_AG+GG (1.25 (1.05–1.49); P = 0.012) were implicated in hypertension. Hypertriglyceridemia was linked to the rs2393791_T (1.14 (1.02–1.27); P = 0.018), rs7310409_G (1.12 (1.01–1.25); P = 0.031), rs1169310_G (1.15 (1.04–1.28); P = 0.010), and rs1169313_CT+TT (1.24 (1.06–1.45); P = 0.008) and high low density lipoprotein-cholesterol levels were associated with rs2259820_T (1.23 (1.07–1.41); P = 0.004), rs2464196_T (1.22 (1.06–1.39); P = 0.004), and rs2259816_T (1.18 (1.02–1.36); P = 0.023). A 7-mer haplotype CATATAC (χ 2 = 7.50; P = 0.0062), constructed from the studied SNPs, was associated with MI, and CATATA implicated in T2DM (χ 2 = 3.94; P = 0.047). Hypertriglyceridemia was linked to TGCGGG (χ 2 = 4.26; P = 0.039), and obesity to ACGGGT (χ 2 = 5.04; P = 0.025). Our results suggest that the HNF1a is a common susceptibility gene for MI, T2DM, hypertension, and dyslipidemia.

Evaluation of the HNF1a gene as a risk factor for metabolic syndrome in the Saudi population

The hepatic nuclear factor 1 alpha (HNF1a) is found predominantly in the liver and pancreatic islet cells where it regulates tissue specific expression of several genes involved in metabolic syndrome pathways. While the HNF1a has been associated with type 2 diabetes mellitus and elevated susceptibility to coronary artery disease, its role in the onset and development of the latter is yet to be clearly explained. We selected 7 familial SNPs to evaluate the role of the HNF1a gene in metabolic risk factors, such as type 2 diabetes mellitus (T2DM), hypertension, obesity and dyslipidaemia. The rs2259820 T [1.10(1.01–1.20); p=0.024] and its dominant mode of inheritance rs2259820 (CT+TT) [1.18(1.03–1.35); p=0.020] conferred risk for T2DM (2550 cases vs 2081 controls). The rs1169310 G [1.10(1.00–1.22); p=0.045] and rs1169313 T [1.11(11.01–1.22); p=0.038] conferred risk for hypertriglyceridaemia (hTG; 1160 vs 3156). On the other hand, rs2464196 T [0.92(0.84–1.00); p=0.039], and rs2464196 TT [0.86(0.75–0.99); p=0.030] were protective against acquiring the disease. Furthermore, the rs7310409 (AG+GG) (p=0.023) and rs2393791 (CT+TT) (p=0.041) were protective against acquiring hypercholesterolaemia, and rs1169310 G (p=0.045) against hTG. Our data suggests that NHF1a is a risk factor for metabolic syndrome.

High-purity Hepatic Lineage Differentiated from Dental Pulp Stem Cells in Serum-free Medium

IntroductionWe have previously differentiated hepatocyte like cells from deciduous tooth pulp stem and extracted third molar pulp stem cells with a protocol that used fetal bovine serum, but it showed high contaminations of nondifferentiated cells. Both the lower purity of hepatically differentiated cells and usage of serum are obstacles for application of cell therapy or regenerative medicine. Objective of this study was to investigate the capacity for and purity of hepatocyte-like differentiation of CD117-positive dental pulp stem cells without serum. MethodsMesenchymal cells from human deciduous and extracted third molar pulp were isolated and expanded in vitro. We separated CD117-positive cells by using a magnetic-activated cell sorter. The cells were characterized immunofluorescently by using known stem cell markers. For hepatic differentiation, the media were supplemented with hepatic growth factor, insulin-transferrin-selenium-x, dexamethasone, and oncostatin M. Expression of hepatic markers alpha fetoprotein, albumin, hepatic nuclear factor-4 alpha, insulin-like growth factor-1, and carbamoyl phosphate synthetase was examined immunofluorescently after differentiation. The amount of differentiated cells was assessed by using flow cytometry. Glycogen storage and urea concentration in the medium were defined. ResultsBoth cell cultures demonstrated a number of cells positive for all tested hepatic markers after differentiation, ie, albumin-positive cells were almost 90% of differentiated deciduous pulp cells. The concentration of urea in the media increased significantly after differentiation. Significant amount of cytoplasmic glycogen storage was found in the cells. ConclusionsWithout serum both cell types differentiated into high-purity hepatocyte-like cells. These cells offer a source for hepatocyte lineage differentiation for transplantation in the future.

Studies in mice, hamsters, and rats demonstrate that repression of hepatic apoA-I expression by taurocholic acid in mice is not mediated by the farnesoid-X-receptor

It is claimed that apoA-I expression is repressed in mice by cholic acid (CA) and its taurine conjugate, taurocholic acid (TCA) via farnesoid X receptor (FXR) activation. We measured apoA-I expression in mice, hamsters, and rats treated with highly potent and selective synthetic FXR agonists or with TCA. All of the synthetic agonists bound to FXR with high affinity in a scintillation proximity assay. However, TCA did not compete with the radioligand up to the highest concentration used (100 μM). The C-site regulatory region of apoA-I, through which FXR has been reported to regulate its expression, is completely conserved across the species investigated. In both male and female human apoA-I-transgenic mice, we reproduced the previously reported strong inhibition of human apoA-I expression upon treatment with the typical supraphysiological dose of TCA used in such studies. However, in contrast to some previous reports, TCA did not repress murine apoA-I expression in the same mice. Also, more-potent and -selective FXR agonists did not affect human or murine apoA-I expression in this model. In LDL receptor-deficient mice and Golden Syrian hamsters, selective FXR agonists did not affect apoA-I expression, whereas in Wistar rats, some even increased apoA-I expression. In conclusion, selective FXR agonists do not repress apoA-I expression in rodents. Repression of human apoA-I expression by TCA in transgenic mice is probably mediated through FXR-independent mechanisms.