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Maturity-onset diabetes of the young type 3 (MODY3) is a non-ketotic form of diabetes associated with poor insulin secretion. Over the past years, several studies have reported the association of missense mutations in the Hepatocyte Nuclear Factor 1 Alpha (HNF1A) with MODY3. Missense mutations in the POU homeodomain (POUH) of HNF1A hinder binding to the DNA, thereby leading to a dysfunctional protein. Missense mutations of the HNF1A were retrieved from public databases and subjected to a three-step computational mutational analysis to identify the underlying mechanism. First, the pathogenicity and stability of the mutations were analyzed to determine whether they alter protein structure and function. Second, the sequence conservation and DNA-binding sites of the mutant positions were assessed; as HNF1A protein is a transcription factor. Finally, the biochemical properties of the biological system were validated using molecular dynamic simulations in Gromacs 4.6.3 package. Two arginine residues (131 and 203) in the HNF1A protein are highly conserved residues and contribute to the function of the protein. Furthermore, the R131W, R131Q, and R203C mutations were predicted to be highly deleterious by in silico tools and showed lower binding affinity with DNA when compared to the native protein using the molecular docking analysis. Triplicate runs of molecular dynamic (MD) simulations (50ns) revealed smaller changes in patterns of deviation, fluctuation, and compactness, in complexes containing the R131Q and R131W mutations, compared to complexes containing the R203C mutant complex. We observed reduction in the number of intermolecular hydrogen bonds, compactness, and electrostatic potential, as well as the loss of salt bridges, in the R203C mutant complex. Substitution of arginine with cysteine at position 203 decreases the affinity of the protein for DNA, thereby destabilizing the protein. Based on our current findings, the MD approach is an important tool for elucidating the impact and affinity of mutations in DNA-protein interactions and understanding their function.

Maturity-onset diabetes of the young type 3 (MODY3) disorder is characterized by an autosomal dominant type of inheritance and highly heterogeneous clinical phenotype influenced by type and position of mutation in the HNF1A gene. We reprogrammed dermal fibroblasts derived from a patient with MODY3 carrying a heterozygous mutation in the site encoding the transactivation domain of the HNF1A protein (с. 864delGinsCC, p.Gly292ArgfsTer25) into iPSCs using transfection with self-replicating RNA vector. Obtained iPSCs (ERCi004‑A line) proliferate in dense monolayer cell colonies, have a normal karyotype (46,XX), express pluripotency markers (OCT4, SOX2, TRA-1-60). The functional pluripotency of iPSCs was confirmed by their ability to form embryoid bodies and differentiate into the three germ layers (ecto-, endo-, and mesoderm). Sanger sequencing of iPSCs confirmed the presence of pathogenic heterozygous mutation in the HNF1A gene. This cell line could be useful to modeling of MODY3 pathology to improve understanding of the mechanism of the transactivation domain mutation, as well as a potential source for autologous cell-based therapy.

Mutations in hepatocyte nuclear factor (HNF)1A gene cause the most common form of Maturity-onset diabetes of the young (MODY), a monogenic subtype of diabetes mellitus. Functional characterization of mutant proteins reveals that mutations may disrupt DNA binding capacity, transactivation ability and nuclear localization of HNF1A depending on the position of the mutation. Previously identified Arg271Trp and Ser345Tyr mutations in HNF1A were found to be defective in nuclear localization. Arg271 residue resides in a region similar to classical nuclear localization signal (NLS) motif, while Ser345 does not. Importin α family members recognize NLS motifs on cargo proteins and subsequently translocate them into nucleus. Here, we first investigated the nuclear localization mechanism of wild type HNF1A protein. For this purpose, we analyzed the interaction of HNF1A with three mouse homolog importin α proteins (KPNA2, KPNA4 and KPNA6) by co-immunoprecipitation assay and molecular docking simulation. Hereby, KPNA6 was identified as the main import receptor, which is responsible for the transport of HNF1A into the nucleus. Immunolocalization studies in mouse pancreatic cells (Min6) also confirmed the co-localization of HNF1A and KPNA6 in the cytoplasm. Secondly, the interaction between KPNA6 and mutant HNF1A proteins (Arg271Trp and Ser345Tyr) was assessed. Co-immunoprecipitation studies revealed a reduced interaction compared to wild type HNF1A. Our study demonstrated for the first time that HNF1A transcription factor is recognized and transported by importin/karyopherin import family, and mutations in NLS motifs may disrupt the interaction leading to nuclear localization abnormalities and MODY phenotype.

Background and objectives: Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a new target for lowering serum cholesterol levels. PCSK9 inhibition retards degradation of low-density lipoprotein receptor (LDLR), resulting in enhancement of LDL-cholesterol uptake in the liver. Daily intake of foodstuffs containing compounds which inhibit PCSK9 activity is expected to prevent hypercholesterolemia. Methods: We constructed a food extracts library and screened for PCSK9 inhibition. A human hepatocellular cell line (HepG2) was treated with test samples and cultured for one day. Secreted mature PCSK9 proteins from the culture medium were determined by western blotting. Active compounds in the food extracts responsible for PCSK9 inhibition were separated and isolated by chromatography. Chemical structures of the compounds were determined by LC-Q-TOF-MS and NMR analyses. To investigate the mechanisms of PCSK9 inhibition in the food items, HepG2 cells were transfected with the siRNA of PCSK9 regulators and then treated with the active compound. Results: Female hop cones (Humulus lupulus L.) and lemon peel showed PCSK9 inhibitory activity. The active compounds responsible for inhibition of PCSK9 were identified as lupulone and 5-geranyloxy-7-methoxycoumarin from hop and lemon, respectively. The active compounds contained an isoprenoid side-chain and prenyl and geranyl moieties. We also found PCSK9 inhibitors in natural products: xanthohumol, bergamottin and a-mangostin, all of which contained an isoprenoid side-chain. It is likely that isoprenoid side-chain contributes to PCSK9 inhibition because the basic skeletons of the active compounds are different (phloroglucinol derivative, coumarin, flavonoid, xanthonoid). Of the compounds tested, lupulone showed the strongest PCSK9 inhibitory activity. RNAi experiments showed that knock down of hepatocyte nuclear factor 1a (HNF1a), a positive regulator of PCSK9, impaired the PCSK9 inhibitory activity of lupulone. Furthermore, lupulone decreased HNF1a protein expression in HepG2, suggesting that lupulone inhibits PCSK9 expression through HNF1a downregulation. Conclusions: We isolated and identified PCSK9 inhibitors from food and natural products and suggest HNF1a is involved in the PCSK9 inhibitory mechanisms of lupulone.

BackgroundHNF1A gene regulates liver‐specific genes, and genes that have a role in glucose metabolism, transport, and secretion of insulin. HNF1A gene mutations are frequently associated with type 2 diabetes. HNF1A protein has three domains: the dimerization domain, the DNA‐binding domain, and the trans‐activation domain. Some mutations in the dimerization or DNA‐binding domains have no influence on the normal allele, while others have dominant negative effects. The I27L, A98V, and S487N polymorphisms are common variants of the HNF1A gene; they have been found in T2D and non‐diabetic subjects.Methods and ResultsWe searched for mutations in the first three exons of the HNF1A gen in an Amerindian population of 71 diabetic patients. DNA sequencing revealed the previously reported I27L polymorphism (c.79A>C) in 53% of diabetic patients and in 67% of the control group. Thus, the I27L/L27L polymorphism might be a marker of Amerindians. In addition, we found the c.422_423InsT mutation in the HNF1A gene of one patient, which had not been previously reported. This mutation resulted in a frame shift of the open reading frame and a new translation stop in codon 187, leading to a truncated polypeptide of 186 amino acids (Q141Hfs*47). This novel mutation affects the DNA‐binding capacity of the mutant HNF1A protein by EMSA; its intracellular localization by fluorescence and confocal microscopy, and a dominant‐negative effect affecting the DNA‐binding capacity of the normal HNF1A by EMSA. We also studied the homology modeling structure to understand the effect of this mutation on its DNA‐binding capacity and its dominant negative effect.ConclusionThe HNF1A Q141Hfs*47 mutant polypeptide has no DNA‐binding capacity and exerts a dominant negative effect on the HNF1A protein. Therefore, it might produce severe phenotypic effects on the expression levels of a set of β‐cell genes. Consequently, its screening should be included in the genetic analysis of diabetic patients after more functional studies are performed.

Maturity-onset diabetes of the young type 3 (MODY3) disorder is characterized by an autosomal dominant type of inheritance and highly heterogeneous clinical phenotype influenced by type and position of mutation in the HNF1A gene. We reprogrammed dermal fibroblasts derived from a patient with MODY3 carrying a heterozygous mutation in the site encoding the transactivation domain of the HNF1A protein (c. 864delGinsCC, p.Gly292ArgfsTer25) into iPSCs using transfection with self-replicating RNA vector. Obtained iPSCs (ERCi004-A line) proliferate in dense monolayer cell colonies, have a normal karyotype (46,XX), express pluripotency markers (OCT4, SOX2, TRA-1-60). The functional pluripotency of iPSCs was confirmed by their ability to form embryoid bodies and differentiate into the three germ layers (ecto-, endo-, and mesoderm). Sanger sequencing of iPSCs confirmed the presence of pathogenic heterozygous mutation in the HNF1A gene. This cell line could be useful to modeling of MODY3 pathology to improve understanding of the mechanism of the transactivation domain mutation, as well as a potential source for autologous cell-based therapy.Competing Interest StatementThe authors have declared no competing interest.

Maturity-onset diabetes of the young (MODY) is a genetically heterogeneous group of monogenic endocrine disorders that is characterised by autosomal dominant inheritance and pancreatic β-cell dysfunction. These patients are commonly misdiagnosed with type 1 or type 2 diabetes, as the clinical symptoms largely overlap. Even though several biomarkers have been tested none of which could be used as single clinical discriminator. The correct diagnosis for individuals with MODY is of utmost importance, as the applied treatment depends on the gene mutation or is subtype-specific. Moreover, in patients with HNF1A-MODY, additional clinical monitoring can be included due to the high incidence of vascular complications observed in these patients. Finally, stratification of MODY patients will enable better and newer treatment options for MODY patients, once the disease pathology for each patient group is better understood. In the current review the clinical characteristics and the known disease-related abnormalities of the most common MODY subtypes are discussed, together with the up-to-date applied diagnostic criteria and treatment options. Additionally, the usage of pluripotent stem cells together with CRISPR/Cas9 gene editing for disease modelling with the possibility to reveal new pathophysiological mechanisms in MODY is discussed.

Understanding the genetic factors of diabetes is essential for addressing the global increase in type 2 diabetes. HNF1A mutations cause a monogenic form of diabetes called maturity-onset diabetes of the young (MODY), and HNF1A single-nucleotide polymorphisms are associated with the development of type 2 diabetes. Numerous studies have been conducted, mainly using genetically modified mice, to explore the molecular basis for the development of diabetes caused by HNF1A mutations, and to reveal the roles of HNF1A in multiple organs, including insulin secretion from pancreatic beta cells, lipid metabolism and protein synthesis in the liver, and urinary glucose reabsorption in the kidneys. Recent studies using human stem cells that mimic MODY have provided new insights into beta cell dysfunction. In this article, we discuss the involvement of HNF1A in beta cell dysfunction by reviewing previous studies using genetically modified mice and recent findings in human stem cell-derived beta cells.

There is growing evidence of the role of long non-coding RNAs (lncRNAs) in cervical cancer (CC). The objective was to discuss whether exosomal lncRNA HNF1A-AS1 impacted drug resistance in CC via binding to microRNA-34b (miR-34b) and regulating TUFT1 expression. The expression of HNF1A-AS1 in normal cervical epithelial cells, cisplatin (DDP)-sensitive cell line (HeLa/S) and DDP-resistant cell line (HeLa/DDP) cells were detected. HeLa/S and HeLa/DDP cells were interfered with HNF1A-AS1 to determine IC , proliferation, colony formation and apoptosis of CC cells. The exosomes were isolated and identified. Subcellular localization of HNF1A-AS1, expression of miR-34b and TUFT1 in receptor cells were also verified. The binding site between HNF1A-AS1 and miR-34b, together with miR-34b and TUFT1 were confirmed. Tumorigenic ability of cells in nude mice was also detected. HNF1A-AS1 was upregulated in DDP-resistant cell line HeLa/DDP. Silencing HNF1A-AS1 suppressed CC cell proliferation and promoted its apoptosis. HNF1A-AS1 was found to act as a competing endogenous RNA (ceRNA) of miR-34b to promote the expression of TUFT1. Exosomes shuttled HNF1A-AS1 promoted the proliferation and drug resistance of CC cells and inhibited their apoptosis by upregulating the expression of TUFT1 and downregulating miR-34b. Furthermore, suppressed exosomal HNF1A-AS1 in combination with DDP inhibited tumor growth in nude mice. Our study provides evidence that CC-secreted exosomes carrying HNF1A-AS1 as a ceRNA of miR-34b to promote the expression of TUFT1, thereby promoting the DDP resistance in CC cells.

Background Pancreatic cancer is poorly characterized at genetic and non-genetic levels. The current study evaluates in a large cohort of patients the prognostic relevance of molecular subtypes and key transcription factors in pancreatic ductal adenocarcinoma (PDAC). Methods We performed gene expression analysis of whole-tumor tissue obtained from 118 surgically resected PDAC and 13 histologically normal pancreatic tissue samples. Cox regression models were used to study the effect on survival of molecular subtypes and 16 clinicopathological prognostic factors. In order to better understand the biology of PDAC we used iRegulon to identify transcription factors (TFs) as master regulators of PDAC and its subtypes. Results We confirmed the PDAssign gene signature as classifier of PDAC in molecular subtypes with prognostic relevance. We found molecular subtypes, but not clinicopathological factors, as independent predictors of survival. Regulatory network analysis predicted that HNF1A/B are among thousand TFs the top enriched master regulators of the genes expressed in the normal pancreatic tissue compared to the PDAC regulatory network. On immunohistochemistry staining of PDAC samples, we observed low expression of HNF1B in well differentiated towards no expression in poorly differentiated PDAC samples. We predicted IRF/STAT, AP-1, and ETS-family members as key transcription factors in gene signatures downstream of mutated KRAS. Conclusions PDAC can be classified in molecular subtypes that independently predict survival. HNF1A/B seem to be good candidates as master regulators of pancreatic differentiation, which at the protein level loses its expression in malignant ductal cells of the pancreas, suggesting its putative role as tumor suppressor in pancreatic cancer. Trial registration The study was registered at ClinicalTrials.gov under the number NCT01116791 (May 3, 2010).