Chromosomally Unstable Gastric Cancers Overexpressing Claudin-6 Disclose Cross-Talk between HNF1A and HNF4A, and Upregulated Cholesterol Metabolism.

(1) Abnormally increased expression of claudin-6 in gastric cancer is considered a prognostic marker of the chromosomal unstable molecular subtype. However, a detailed molecular profile analysis of differentially expressed genes and affected pathways associated with claudin-6 increased (Cldn6high) expression has not been assessed. (2) The TCGA Stomach Adenocarcinoma Pan-Cancer Atlas Data was evaluated using Cytoscape's Gene Mania, MCODE, and Cytohubba bioinformatic software. (3) 96.88% of Cldn6high gastric cancer tumors belonging to the chromosomal unstable molecular subtype are associated with a worse prognosis. Cldn6expression coincided with higher mutations in TP53, MIEN1, STARD3, PGAP3, and CCNE1 genes compared to Cldn6low expression. In Cldn6high cancers, 1316 genes were highly expressed. Cholesterol metabolism was the most affected pathway as APOA1, APOA2, APOH, APOC2, APOC3, APOB-100, LDL receptor-related protein 1/2, Sterol O-acyltransferase, STARD3, MAGEA-2, -3, -4, -6, -9B, and -12 genes were overexpressed in Cldn6high gastric cancers; interestingly, APOA2 and MAGEA9b were identified as top hub genes. Functional enrichment of DEGs linked HNF-4α and HNF-1α genes as highly expressed in Cldn6high gastric cancer. (4) Our results suggest that APOA2 and MAGEA9b could be considered as prognostic markers for Cldn6high gastric cancers.

PPARα/RXRα downregulates amino acid catabolism in the liver via interaction with HNF4α promoting its proteasomal degradation.

The preservation of body proteins is essential to guarantee their functions in organisms. Therefore, the utilization of amino acids as energy substrates is regulated by a precise fine-tuned mechanism. Recent evidence suggests that the transcription factors peroxisome proliferator-activated receptor alpha (PPARα) and hepatocyte nuclear factor 4 alpha (HNF4α) are involved in this regulatory mechanism. Thus, the aim of this study was to determine how these transcription factors interact to regulate the expression of amino acid catabolism genes. In vivo studies using PPARα-knockout mice (Pparα-null) fed different amounts of dietary protein showed that in the absence of PPARα, there was a significant increase in HNF4α abundance in the liver, which corresponded with an increase in amino acid catabolizing enzyme (AACE) expression and the generation of increased amounts of postprandial urea. Moreover, this effect was proportional to the increase in dietary protein consumed. Chromatin immunoprecipitation assays showed that HNF4α can bind to the promoter of AACE serine dehydratase (SDS), an effect that was potentiated by dietary protein in the Pparα-null mice. The mechanistic studies revealed that the presence of retinoid X receptor alpha (RXRα) is essential to repress HNF4α activity in the presence of PPARα, and this interaction accelerates HNF4α degradation via the proteasome pathway. These results showed that PPARα can downregulate liver amino acid catabolism in the presence of RXRα by inhibiting HNF4α activity.

Association of the T130I Variant of the HNF4A Gene with Metabolic Syndrome and Its Components in Mexican Children.

Background: Metabolic syndrome (MetS), a cluster of risk factors, leads to cardiovascular disease (CVD) and type 2 diabetes (T2D). The second leading cause of mortality in Mexico is T2D. Genetic factors participate in the pathogenesis of MetS. The HNFA gene encodes a transcription factor that plays a crucial role in energy homeostasis by regulating the metabolism of glucose and lipids. This study aimed to investigate the association of the T130I variant of the HNF4A gene in Mexican children with MetS and its constituent components. Methods: The study was performed in 477 children from elementary schools. MetS was classified according to the de Ferranti definition. Biochemical parameters were measured and genotyping was performed. Logistic regression under a dominant genetic model was used to analyze the association of the T130I variant of the HNF4A gene with MetS and with its components separately. Results: The prevalence of MetS was 25.4%, and 18.9% in children who presented insulin resistance. Interestingly, this is the first time that a significant association between the T130I variant of the HNF4A gene and MetS has been reported [odds ratios (OR) = 2.31; 95% confidence interval (CI) 1.10-4.83; P = 0.026]. Moreover, carriers of the risk allele show higher abdominal obesity (OR = 1.20; 95% CI 1.09-4.50; P = 0.029). These findings highlight the active role of genetic variants in the pathogenesis of MetS in Mexican children. Conclusions: The high prevalence of children with MetS and insulin resistance places this population at an elevated risk of early CVD and T2D. The Clinical Trial Registration Number is HJM2315/14C.

Genome-wide 5-hydroxymethylcytosine (5hmC) emerges at early stage of in vitro differentiation of a putative hepatocyte progenitor.

A basic question linked to differential patterns of gene expression is how cells reach different fates despite using the same DNA template. Since 5-hydroxymethylcytosine (5hmC) emerged as an intermediate metabolite in active DNA demethylation, there have been increasing efforts to elucidate its function as a stable modification of the genome, including a role in establishing such tissue-specific patterns of expression. Recently we described TET1-mediated enrichment of 5hmC on the promoter region of the master regulator of hepatocyte identity, HNF4A, which precedes differentiation of liver adult progenitor cells in vitro. Here, we studied the genome-wide distribution of 5hmC at early in vitro differentiation of human hepatocyte-like cells. We found a global increase in 5hmC as well as a drop in 5-methylcytosine after one week of in vitro differentiation from bipotent progenitors, at a time when the liver transcript program is already established. 5hmC was overall higher at the bodies of overexpressed genes. Furthermore, by modifying the metabolic environment, an adenosine derivative prevents 5hmC enrichment and impairs the acquisition of hepatic identity markers. These results suggest that 5hmC could be a marker of cell identity, as well as a useful biomarker in conditions associated with cell de-differentiation such as liver malignancies.

More than kin, less than kind: one family and the many faces of diabetes in youth

SUMMARY Identification of the correct etiology of diabetes brings important implications for clinical management. In this report, we describe a case of a 4-year old asymptomatic girl with diabetes since age 2, along with several individuals in her family with different etiologies for hyperglycemia identified in youth. Genetic analyses were made by Sanger sequencing, laboratory measurements included HbA1c, lipid profile, fasting C-peptide, pancreatic auto-antibodies (glutamic acid decarboxylase [GAD], Islet Antigen 2 [IA-2], and anti-insulin). We found a Gly178Ala substitution in exon 5 of GCK gene in three individuals co-segregating with diabetes, and type 1 diabetes was identified in two other individuals based on clinical and laboratory data. One individual with previous gestational diabetes and other with prediabetes were also described. We discuss difficulties in defining etiology of hyperglycemia in youth in clinical practice, especially monogenic forms of diabetes, in spite of the availability of several genetic, laboratory, and clinical tools.

Susceptibility background for type 2 diabetes in eleven Mexican Indigenous populations: HNF4A gene analysis.

The genetic risk of developing type 2 diabetes (T2D) increases in parallel with the proportion of Native American ancestry. Mestizo Mexicans have a 70% Native Amerindian genetic background. The T130I polymorphism in the HNF4A gene has been associated with early-onset T2D in mestizo Mexicans. Thus, the aim of the present study was to evaluate the frequency and relationship of the T130I variant in the HNF4A gene with risk factors for developing T2D in eleven indigenous groups from Mexico. In two groups, all exons of the HNF4A gene were directly sequenced; in the remaining the T130I polymorphism was analyzed by restriction fragment length polymorphism. Ancestry informative markers were assessed to confirm the Amerindian component. An additional analysis of EHH was carried out. Interestingly, HNF4A gene screening revealed only the presence of the T130I polymorphism. The range frequency of the risk allele (T) in the indigenous groups was from 2.7 to 16%. Genotypic frequencies (T130I/I130I) were higher and significantly different from those of all of the populations included in the HapMap Project (P < 0.005). EHH scores suggest a positive selection for T130I polymorphism. Metabolic traits indicate a relationship between the T130I/I130I genotypes with high triglyceride concentrations in the indigenous groups (P < 0.005). These results strongly suggest that the high frequency of the T130I polymorphism and its biological relationship with dysfunction in lipid metabolism in Mexican indigenous groups is a risk factor for the developing of T2D in Mexicans.

HNF4A expression as a potential diagnostic tool to discriminate primary gastric cancer from breast cancer metastasis in a Brazilian cohort.

BACKGROUND: Among the many challenges in cancer diagnosis is the early distinction between metastatic cancer and a secondary tumor. This difficulty stems from the lack of markers that offer high sensitivity and specificity and can be easily applied in routine laboratory work. An example of this challenge is distinguishing gastric metastases originating from breast cancer from a gastric primary tumor. Hepatocyte nuclear factor 4 alpha (HNF4A) has been suggested as a potential marker in these cases. The aim of this study was to analyze the expression of HNF4A, estrogen receptor (ER), progesterone receptor (PR) and gross cystic disease fluid protein 15 (GCDFP-15) in a Brazilian cohort. METHODS: We performed immunohistochemistry analysis of HNF4A, ER, PR and GCDFP-15 in 126 patients divided into three cohorts: primary breast cancer, primary gastric cancer and both types of tumors. RESULTS: Our data confirmed the sensitivity and specificity of the HNF4A marker compared to other currently used clinical markers. CONCLUSION: HNF4A alone could be a gold standard marker for distinguishing primary gastric cancer from breast metastasis, thus validating its potential clinical use, especially in populations with high genetic diversity.

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.

Effect of Cis-palmitoleic acid supplementation on inflammation and expression of HNF4γ, HNF4α and IL6 in patients with ulcerative colitis.

BACKGROUND: Cis-palmitoleic acid (Omega-7 fatty acid) is a monounsaturated fatty acid (MUFA) associated with anti-inflammatory process through specific protein interactions such as HNF4γ and HNF4α, these two genes are related to the immune response in ulcerative colitis (UC) they may act as a mediator of anti-inflammatory action. The aim of this study was to evaluate the effect of Cis-palmitoleic acid supplementation on inflammatory activity and the expression of genes HNF4γ, HNF4α and IL6 in the colonic mucosa of patients with active UC. METHODS: A double-blind, randomized, placebo-controlled pilot study was conducted in 20 patients with UC. A dose of 720 mg/day of Cis-palmitoleic acid was orally administered during 8 weeks and Mayo Clinic score was used for the assessment of clinical activity in UC before and after treatment with Cis-palmitoleic acid and placebo. RESULTS: A total of 20 patients with UC were randomized to receive Cis-palmitoleic acid or placebo. Significant changes in the biochemical markers of inflammation were found in UC patients before and after treatment with Cis-palmitoleic acid vs. placebo such as total protein (P=0.02), hs-CRP (P=0.04) and ESR (P<0.05). The gene expression of HNF4γ and HNF4α were found to be increased in the Cis-palmitoleic acid group compared to placebo group (P=0.05 and P=0.07 respectively) as well as significant reduction upon IL6 expression in the Cis-palmitoleic acid group (P=0.005). CONCLUSIONS: Cis-palmitoleic acid as co-adjuvant therapy for 8 weeks seems to decrease the inflammatory activity through the increased expression of HNF4α and HNF4γ in patients with UC.

More than kin, less than kind: one family and the many faces of diabetes in youth.

Identification of the correct etiology of diabetes brings important implications for clinical management. In this report, we describe a case of a 4-year old asymptomatic girl with diabetes since age 2, along with several individuals in her family with different etiologies for hyperglycemia identified in youth. Genetic analyses were made by Sanger sequencing, laboratory measurements included HbA1c, lipid profile, fasting C-peptide, pancreatic auto-antibodies (glutamic acid decarboxylase [GAD], Islet Antigen 2 [IA-2], and anti-insulin). We found a Gly178Ala substitution in exon 5 of GCK gene in three individuals co-segregating with diabetes, and type 1 diabetes was identified in two other individuals based on clinical and laboratory data. One individual with previous gestational diabetes and other with prediabetes were also described. We discuss difficulties in defining etiology of hyperglycemia in youth in clinical practice, especially monogenic forms of diabetes, in spite of the availability of several genetic, laboratory, and clinical tools.

Molecular Characterization of the Lipid Genome-Wide Association Study Signal on Chromosome 18q11.2 Implicates HNF4A-Mediated Regulation of the TMEM241 Gene.

OBJECTIVE: We recently identified a locus on chromosome 18q11.2 for high serum triglycerides in Mexicans. We hypothesize that the lead genome-wide association study single-nucleotide polymorphism rs9949617, or its linkage disequilibrium proxies, regulates 1 of the 5 genes in the triglyceride-associated region. APPROACH AND RESULTS: We performed a linkage disequilibrium analysis and found 9 additional variants in linkage disequilibrium (r(2)>0.7) with the lead single-nucleotide polymorphism. To select the variants for functional analyses, we annotated the 10 variants using DNase I hypersensitive sites, transcription factor and chromatin states and identified rs17259126 as the lead candidate variant for functional in vitro validation. Using luciferase transcriptional reporter assay in liver HepG2 cells, we found that the G allele exhibits a significantly lower effect on transcription (P<0.05). The electrophoretic mobility shift and ChIPqPCR (chromatin immunoprecipitation coupled with quantitative polymerase chain reaction) assays confirmed that the minor G allele of rs17259126 disrupts an hepatocyte nuclear factor 4 α-binding site. To find the regional candidate gene, we performed a local expression quantitative trait locus analysis and found that rs17259126 and its linkage disequilibrium proxies alter expression of the regional transmembrane protein 241 (TMEM241) gene in 795 adipose RNAs from the Metabolic Syndrome In Men (METSIM) cohort (P=6.11×10(-07)-5.80×10(-04)). These results were replicated in expression profiles of TMEM241 from the Multiple Tissue Human Expression Resource (MuTHER; n=856). CONCLUSIONS: The Mexican genome-wide association study signal for high serum triglycerides on chromosome 18q11.2 harbors a regulatory single-nucleotide polymorphism, rs17259126, which disrupts normal hepatocyte nuclear factor 4 α binding and decreases the expression of the regional TMEM241 gene. Our data suggest that decreased transcript levels of TMEM241 contribute to increased triglyceride levels in Mexicans.

CUL4B, NEDD4, and UGT1As involve in the TGF-ß signalling in hepatocellular carcinoma.

UNLABELLED:  Introduction and Aim. TGF-ß signalling is involved in pathogenesis and progress of hepatocellular carcinoma (HCC). This bioinformatics study consequently aims to determine the underlying molecular mechanism of TGF- ß activation in HCC cells. MATERIAL AND METHODS: Dataset GSE10393 was downloaded from Gene Expression Omnibus, including 2 Huh-7 (HCC cell line) samples treated by TGF- ß (100 pmol/L, 48 h) and 2 untreated samples. Differentially expressed genes (DEGs) were screened using Limma package (false discovery rate < 0.05 and |log2 fold change| > 1.5), and then enrichment analyses of function, pathway, and disease were performed. In addition, protein-protein interaction (PPI) network was constructed based on the PPI data from multiple databases including INACT, MINT, BioGRID, UniProt, BIND, BindingDB, and SPIKE databases. Transcription factor (TF)-DEG pairs (Bonferroni adjusted p-value < 0.01) from ChEA database and DEG-DEG pairs were used to construct TF-DEG regulatory network. Furthermore, TF-pathway-DEG complex network was constructed by integrating DEG-DEG pairs, TF-DEG pairs, and DEG-pathway pairs. RESULTS: Totally, 209 DEGs and 30 TFs were identified. The DEGs were significantly enriched in adhesion-related functions. PPI network indicted hub genes such as CUL4B and NEDD4. According to the TF-DEG regulatory network, the two hub genes were targeted by SMAD2, SMAD3, and HNF4A. Besides, the 11 pathways in TF-pathway-DEG network were mainly enriched by UGT1A family and CYP3A7, which were predicted to be regulated by SMAD2, SMAD3, SOX2, TP63, and HNF4A. CONCLUSIONS: TGF- ß might influence biological processes of HCC cells via SMAD2/SMAD3-NEDD4, HNF4A-CUL4B/NEDD4, SOX2/TP63/HNF4A-CYP3A7, and SMAD2/SMAD3/SOX2/TP63/HNF4A-UGT1As regulatory pathways.

Hepatocyte nuclear factor-4α, a multifunctional nuclear receptor associated with cardiovascular disease and cholesterol catabolism.

Cardiovascular diseases (CVDs), the leading cause of death worldwide, are associated with high plasma cholesterol levels. The conversion of cholesterol to bile acids (BAs) accounts for about 50% of total cholesterol elimination from the body. This phenomenon occurs in the liver and is regulated by nuclear receptors such as hepatocyte nuclear factor-4α (HNF-4α). Therefore, special emphasis is given to HNF-4α properties and its multifunctional role, particularly in the conversion of cholesterol to BAs. HNF-4α is a highly conserved transcription factor that has the potential capacity to transactivate a vast number of genes, including CYP7 which codes for cholesterol 7α-hydroxylase (CYP7A1; EC 1.14.13.17), the rate-limiting enzyme of BA biosynthesis. The fact that HNF-4α transactivation potential can be modulated via phosporylation is of particular interest. Additional findings on structural and functional characteristics of HNF-4α may eventually present alternatives to control the levels of cholesterol in the body and consequently reduce the risk of CVDs.

Association of genetic variants in the HNF4A and HNF1B genes with early onset Type 2 diabetes mellitus in the Indo and Afro-Trinidadian populations

OBJECTIVE: To determine if variation in HNF4A, HNF1B and PAX4 genes is associated with increased risk of early onset Type 2 diabetes mellitus (T2DM) in Indo and Afro-Trinidadians. DESIGN AND METHODS: The promoter, exons and flanking intronic regions of the HFN4A, HNF1B and PAX4 genes were sequenced in 167 T2DM and 61 non-diabetic subjects of South Asian Indian ancestry, and 66 T2DM and 59 non- diabetic subjects of African ancestry. Differences in SNP allele and haplotype frequency between T2DM patients and non-diabetic subjects were calculated, and pairwise linkage disequilibrium was also assessed for regions within these genes. RESULTS: Three variants identified in intron 4 of the HNF4A gene, demonstrated association with early onset T2DM in the Indo-Trinidadian population, rs11574739, P = 0.0032, OR 2.99 (95% CI 1.44-6.22), rs3212194, P = 0.02, OR 2.57 (95% CI 1.17-5.65), rs321219, P = 0.0083, OR 2.72 (95% CI 1.29-5.71). In the HNF1B gene, an intron 7 SNP, rs2269842, was associated with early onset T2DM in both the Indo and Afro-Trinidadian groups, P = 0.012, OR 0.42 (95% CI 0.20-0.87) and, P = 0.012, OR 0.44(95% CI 0.23-0.86) respectively. Both findings are previously unreported. No association was demonstrated with variants typed within the PAX4 gene. CONCLUSIONS: Variants in the HNF4A and HNF1B genes may contribute to increased risk of early onset T2DM in Indo-Trinidadians. HNF1B variants may similarly influence diabetes susceptibility in Afro-Trinidadians. However, further studies are required to fully elucidate the contribution of such variants to the prevalence of diabetes in the Trinidadian population.

Exercise training decreases mitogen-activated protein kinase phosphatase-3 expression and suppresses hepatic gluconeogenesis in obese mice.

Insulin plays an important role in the control of hepatic glucose production. Insulin resistant states are commonly associated with excessive hepatic glucose production, which contributes to both fasting hyperglycaemia and exaggerated postprandial hyperglycaemia. In this regard, increased activity of phosphatases may contribute to the dysregulation of gluconeogenesis. Mitogen-activated protein kinase phosphatase-3 (MKP-3) is a key protein involved in the control of gluconeogenesis. MKP-3-mediated dephosphorylation activates FoxO1 (a member of the forkhead family of transcription factors) and subsequently promotes its nuclear translocation and binding to the promoters of gluconeogenic genes such as phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase). In this study, we investigated the effects of exercise training on the expression of MKP-3 and its interaction with FoxO1 in the livers of obese animals. We found that exercised obese mice had a lower expression of MKP-3 and FoxO1/MKP-3 association in the liver. Further, the exercise training decreased FoxO1 phosphorylation and protein levels of Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and gluconeogenic enzymes (PEPCK and G6Pase). These molecular results were accompanied by physiological changes, including increased insulin sensitivity and reduced hyperglycaemia, which were not caused by reductions in total body mass. Similar results were also observed with oligonucleotide antisense (ASO) treatment. However, our results showed that only exercise training could reduce an obesity-induced increase in HNF-4α protein levels while ASO treatment alone had no effect. These findings could explain, at least in part, why additive effects of exercise training treatment and ASO treatment were not observed. Finally, the suppressive effects of exercise training on MKP-3 protein levels appear to be related, at least in part, to the reduced phosphorylation of Extracellular signal-regulated kinases (ERK) in the livers of obese mice.

Thr130Ile polymorphism of HNF4A gene is associated with gestational diabetes mellitus in Mexican population.

Hepatocyte nuclear factor 4α (HNF4A) is a transcription factor that regulates the expression of genes in the liver, pancreas, kidney, intestine, and other tissues. Previous studies in the Mexican population have shown a high frequency of the Thr130Ile polymorphism and have suggested its important role in the pathogenesis of early-onset type 2 diabetes. The aim of the present study was to determine whether this variant also contributes to gestational diabetes mellitus (GDM) in a Mexican population. We studied 213 unrelated postpartum women and their neonates, who were divided into 2 groups: control and GDM. The control group was formed by 108 healthy postpartum women and their neonates, and the GDM group was formed by 105 postpartum women diagnosed with GDM and their neonates. All subjects were genotyped for the Thr130Ile polymorphism in HNF4A by Taqman allelic discrimination assays and sequencing. Our results showed a higher frequency of the minor allele of the Thr130Ile polymorphism in the GDM group compared with the control group (P = 0.0452; odds ratio, 2.59; 95% confidence interval, 1.02-6.59). With respect to offspring, the frequency of the polymorphism was higher in the offspring of the GDM group than in the offspring of the control group; however, no significant differences between the groups were observed (P = 0.2551; odds ratio, 1.90; 95% confidence interval, 0.99-3.64). The findings suggest that the Thr130Ile polymorphism is associated with GDM in the studied Mexican population.

Hepatocyte nuclear factors 1α/4α and forkhead box A2 regulate the solute carrier 2A2 (Slc2a2) gene expression in the liver and kidney of diabetic rats.

AIMS: Solute carrier 2a2 (Slc2a2) gene codifies the glucose transporter GLUT2, a key protein for glucose flux in hepatocytes and renal epithelial cells of proximal tubule. In diabetes mellitus, hepatic and tubular glucose output has been related to Slc2a2/GLUT2 overexpression; and controlling the expression of this gene may be an important adjuvant way to improve glycemic homeostasis. Thus, the present study investigated transcriptional mechanisms involved in the diabetes-induced overexpression of the Slc2a2 gene. MAIN METHODS: Hepatocyte nuclear factors 1α and 4α (HNF-1α and HNF-4α), forkhead box A2 (FOXA2), sterol regulatory element binding protein-1c (SREBP-1c) and the CCAAT-enhancer-binding protein (C/EBPß) mRNA expression (RT-PCR) and binding activity into the Slc2a2 promoter (electrophoretic mobility assay) were analyzed in the liver and kidney of diabetic and 6-day insulin-treated diabetic rats. KEY FINDINGS: Slc2a2/GLUT2 expression increased by more than 50% (P<0.001) in the liver and kidney of diabetic rats, and 6-day insulin treatment restores these values to those observed in non-diabetic animals. Similarly, the mRNA expression and the binding activity of HNF-1α, HNF-4α and FOXA2 increased by 50 to 100% (P<0.05 to P<0.001), also returning to values of non-diabetic rats after insulin treatment. Neither the Srebf1 and Cebpb mRNA expression, nor the SREBP-1c and C/EBP-ß binding activity was altered in diabetic rats. SIGNIFICANCE: HNF-1α, HNF-4α and FOXA2 transcriptional factors are involved in diabetes-induced overexpression of Slc2a2 gene in the liver and kidney. These data point out that these transcriptional factors are important targets to control GLUT2 expression in these tissues, which can contribute to glycemic homeostasis in diabetes.

Maternal high-fat intake during pregnancy programs metabolic-syndrome-related phenotypes through liver mitochondrial DNA copy number and transcriptional activity of liver PPARGC1A.

UNLABELLED: In this study, we contrasted the hypothesis that maternal diet during pregnancy has an impact on fetal metabolic programming through changes in liver mitochondrial DNA (mtDNA) content and transcriptional activity of Ppargc1a and that these effects are sex specific. METHODS: Rats were fed either high-fat (HFD) or standard chow diet (SCD) during gestation and lactation. The resulting adult male and female offspring were fed either HFD or SCD for an 18-week period, generating eight experimental groups. RESULTS: Maternal HFD feeding during pregnancy is associated with a decreased liver mtDNA copy number (P<.008). This effect was independent of the offspring sex or diet, and was significantly associated with fatty liver when dams were fed HFD (P<.05, adjusted by homeostasis model assessment of insulin resistance, HOMA-IR). We also found that maternal HFD feeding results in a male-specific significant reduction of the liver abundance of Ppargc1a mRNA (P<.004), which significantly impacted peripheral insulin resistance. Liver expression of Ppargc1a was inversely correlated with HOMA-IR (R=-0.53, P<.0003). Only male offspring exposed to a chronic metabolic insult in adult life were insulin resistant and hyperleptinemic, and showed abnormal liver and abdominal fat accumulation. Liver abundance of Tfam, Nrf1, Hnf4a, Pepck and Ppparg mRNA was not associated with maternal programming. In conclusion, maternal high-fat diet feeding during pregnancy programs liver mtDNA content and the transcriptional activity of Ppargc1a, which strongly modulates, in a sex-specific manner, glucose homeostasis and organ fat accumulation in adult life after exposure to a nutritional insult.

Acute exercise reduces hepatic glucose production through inhibition of the Foxo1/HNF-4alpha pathway in insulin resistant mice.

Protein hepatocyte nuclear factor 4alpha (HNF-4alpha) is atypically activated in the liver of diabetic rodents and contributes to hepatic glucose production. HNF-4alpha and Foxo1 can physically interact with each other and represent an important signal transduction pathway that regulates the synthesis of glucose in the liver. Foxo1 and HNF-4alpha interact with their own binding sites in the phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) promoters, and this binding is required for their effects on those promoters. However, the effect of physical activity on the HNF-4alpha/Foxo1 pathway is currently unknown. Here, we investigate the protein levels of HNF-4alpha and the HNF-4alpha/Foxo1 pathway in the liver of leptin-deficient (ob/ob) and diet-induced obese Swiss (DIO) mice after acute exercise. The ob/ob and DIO mice swam for four 30 min periods, with 5 min rest intervals for a total swimming time of 2h. Eight hours after the acute exercise protocol, the mice were submitted to an insulin tolerance test (ITT) and determination of biochemical and molecular parameters. Acute exercise improved insulin signalling, increasing insulin-stimulated Akt and Foxo1 phosphorylation and decreasing HNF-4alpha protein levels in the liver of DIO and ob/ob mice under fasting conditions. These phenomena were accompanied by a reduction in the expression of gluconeogenesis genes, such as PEPCK and G6Pase. Importantly, the PI3K inhibitor LY292004 reversed the acute effect of exercise on fasting hyperglycaemia, confirming the involvement of the PI3K pathway. The present study shows that exercise acutely improves the action of insulin in the liver of animal models of obesity and diabetes, resulting in increased phosphorylation and nuclear exclusion of Foxo1, and a reduction in the Foxo1/HNF-4alpha pathway. Since nuclear localization and the association of these proteins is involved in the activation of PEPCK and G6Pase, we believe that the regulation of Foxo1 and HNF-4alpha activities are important mechanisms involved in exercise-induced improvement of glucose homeostasis in insulin resistant states.