Hepatocyte Nuclear Factor 4α Research Articles

Dendrobium nobile Lindl. alkaloids improve lipid metabolism by increasing LDL uptake through regulation of the LXRα/IDOL/LDLR pathway and inhibition of PCSK9 expression in HepG2 cells.

Dendrobium nobile Lindl. alkaloids (DNLA) are active ingredients that can be extracted from the traditional Chinese herb Dendrobium Nobile Lindl. DNLA exhibits hypoglycemic and antihyperlipidemia effects. However, to the best of our knowledge, the specific molecular mechanism by which DNLA can regulate lipid metabolism remains unclear. The aim of the present study was to investigate the effect of DNLA on lipopolysaccharide (LPS)-induced lipid metabolism in HepG2 cells and its potential mechanism. HepG2 cells were treated with LPS with or without different concentrations of DNLA (0, 0.035, 0.35 and 3.5 µg/ml) for 48 h. Cell viability was then detected using the Cell Counting Kit-8 assay. The 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanideperchlorate-low-density lipoprotein (LDL) uptake assay was used to examine LDL uptake. In addition, possible mechanisms were explored using western blot analysis. The effect of the combination of DNLA with rosuvastatin calcium on the expression levels of the LDL receptor (LDLR) and proprotein convertase subtilisin/Kexin type 9 (PCSK9) was examined. The results indicated that LPS stimulation reduced the uptake of LDL by HepG2 cells, decreased the intracellular LDLR content, and increased the expression levels of inducible degrader of the LDLR (IDOL) and liver X receptor (LXR)α. DNLA intervention reversed all of the aforementioned LPS-induced effects in HepG2 cells. Additional mechanistic experiments revealed that DNLA exerted its effects mainly by regulating the LXRα/IDOL/LDLR pathway. It was shown that DNLA also reduced the expression levels of PCSK9, sterol regulatory element binding protein 2 and hepatocyte nuclear factor 1α. In addition, DNLA decreased the expression levels of PCSK9 in rosuvastatin calcium-induced HepG2 cells. Notably, DNLA was able to decrease 3-hydroxy-3-methylglutaryl-coenzyme A reductase and increase cytochrome p450 7A1 expression at the protein level, which are rate-limiting enzymes in cholesterol synthesis and metabolism. Collectively, these data suggested that DNLA could enhance LDL uptake of HepG2 cells by increasing LDLR expression through the LXRα/IDOL/LDLR pathway to alleviate the effects induced by LPS, suggesting the potential benefit of DNLA in improving lipid metabolism disorders.

Hepatocyte nuclear factor 4α as a sensitive marker for uterine endocervical adenocarcinomas and their precursors.

Hepatocyte nuclear factor (HNF)-4α is a marker of gastrointestinal tumor differentiation; however, its expression in endocervical tumors remains unclear. We aimed to assess the utility of HNF4α expression as a marker for endocervical adenocarcinomas (ECAs) and adenocarcinoma in situs (AISs), and to establish a minimal panel for distinguishing them from nonneoplastic endocervical glandular lesions and metastases. HNF4α expression was analyzed immunohistochemically (positive, H-score ≥10) in 323 tissue samples: 57 endocervical neoplasms including 35 glandular neoplasms and 22 squamous neoplasms, 144 nonneoplastic endocervical lesions, and 122 tumors from other organs. The panel for distinguishing endocervical glandular neoplasms from nonneoplastic glands and from metastases comprised HNF4α, p16, CDX2, and SATB2; staining was assessed. HNF4α was expressed significantly in ECAs and AISs, both HPV-independent and -associated types, but not in nonneoplastic glandular and squamous lesions (p<0.05). The immunohistochemical detection sensitivity and specificity for endocervical ECA and AIS were 77% and 95%, respectively. For AIS alone, these were 79% and 94%, and for ECA alone, 75% and 94%, respectively. Either HNF4α(+) or p16(+) or double positive identified endocervical gland and squamous neoplasms (sensitivity, 96%; specificity, 76%). HNF4α(+) and SATB2(-) and CDX2(-) profiles suggested ECAs (sensitivity, 69%; specificity, 88%). HNF4α(+) and SATB2(+) or CDX2(+) profiles suggested adenocarcinomas of the gastrointestinal or genital tract (sensitivity, 81%; specificity, 88%). HNF4α is a promising marker for detecting both HPV-independent and -associated ECAs and AIS with high accuracy. Its combination with p16, CDX2, and SATB2 has potential use in diagnostic panels.

Hepatocyte-Derived FGF1 Alleviates Isoniazid and Rifampicin-Induced Liver Injury by Regulating HNF4α-Mediated Bile Acids Synthesis.

Isoniazid and rifampicin co-therapy are the main causes of anti-tuberculosis drug-induced liver injury (ATB-DILI) and acute liver failure, seriously threatening human health. However, its pathophysiology is not fully elucidated. Growing evidences have shown that fibroblast growth factors (FGFs) play a critical role in diverse aspects of liver pathophysiology. The aim of this study is to investigate the role of FGFs in the pathogenesis of isoniazid (INH) and rifampicin (RIF)-induced liver injury. Through systematic screening, this study finds that hepatic FGF1 expression is significantly downregulated in both mouse model and human patients challenged with INH and RIF. Hepatocyte-specific Fgf1 deficiency exacerbates INH and RIF-induced liver injury resulted from elevated bile acids (BAs) synthases and aberrant BAs accumulation. Conversely, pharmacological administration of the non-mitogenic FGF1 analog - FGF1ΔHBS significantly alleviated INH and RIF-induced liver injury via restoring BAs homeostasis. Mechanically, FGF1 repressed hepatocyte nuclear factor 4α (Hnf4α) transcription via activating FGF receptor 4 (FGFR4)-ERK1/2 signaling pathway, thus reducing BAs synthase. The findings demonstrate hepatic FGF1 functions as a negative regulator of BAs biosynthesis to protect against INH and RIF-induced liver injury via normalizing hepatic BAs homeostasis, providing novel mechanistic insights into the pathogenesis of ATB-DILI and potential therapeutic strategies for treatment of ATB-DILI.

Study on the molecular mechanisms of rifaximin in the treatment of non‑alcoholic steatohepatitis based on the Helicobacter‑DCA‑Fxr‑Hnf1α signalling pathway.

Non‑alcoholic steatohepatitis (NASH), the more progressive form of non‑alcoholic fatty liver disease, has become a major cause of cirrhosis and liver cancer. The aim of the present study was to investigate the anti‑NASH effect of the nonabsorbable antibiotic rifaximin and its specific molecular mechanisms. A methionine‑choline deficient (MCD) diet was used to induce NASH formation in mice. The mice with NASH were treated with rifaximin to observe its effects on liver fat deposition, hepatocyte inflammation and liver fibrosis. Furthermore, the intestinal microbiota of mice with NASH was analysed by 16S rRNA sequencing and terminal ileal bile acid levels were assessed using liquid chromatography‑electrospray ionization‑tandem mass spectrometry analysis. Furthermore, the correlation between the intestinal microflora and bile acid levels in the terminal ileum was investigated, and the effects of rifaximin on the intestinal Helicobacter‑deoxycholic acid (DCA)‑farnesoid X receptor (Fxr)‑hepatocyte nuclear factor 1α (Hnf1α) signalling pathway were examined. Moreover, analyses of mice after intestinal decontamination with broad‑spectrum antibiotics and of hepatocyte‑specific Hnf1α knockout (Hnf1αH‑KO) mice were used to elucidate the molecular mechanisms by which rifaximin improves NASH. Notably, treatment with rifaximin markedly ameliorated liver steatosis, hepatocyte inflammation and liver fibrosis in mice with MCD diet‑induced NASH. Rifaximin modulated the gut microbiota, especially Helicobacter hepaticus, in mice with NASH. In addition, rifaximin inhibited the intestinal Helicobacter‑DCA‑Fxr‑Hnf1α signalling pathway in mice with NASH. By contrast, rifaximin did not exert an anti‑NASH effect on decontamination‑treated mice or Hnf1αH‑KO mice. Taken together, these results indicated that rifaximin can ameliorate NASH in mice by modulating the Helicobacter‑DCA‑Fxr‑Hnf1α signalling pathway, providing a theoretical basis for the clinical treatment of patients with NASH with rifaximin.

Combined effects and potential mechanisms of phthalate metabolites on serum sex hormones among reproductive-aged women: An integrated epidemiology and computational toxicology study

The reproductive age is a crucial stage for women to bear offspring. However, reproductive-aged women are simultaneously exposed to various phthalates, which may pose a threat to their reproductive health. This study employed generalized linear regression and weighted quantile sum (WQS) regression to explore the associations between monoesters of phthalates (MPAEs) and sex hormones in 913 reproductive-aged women in the National Health and Nutrition Examination Survey. Key risk factors driving hormone disruption were identified based on the weights of the WQS models. Interaction models were used to unravel the synergistic or antagonistic effects between MPAEs. The potential toxicological targets of MPAEs interfering with sex hormone-binding globulin (SHBG) levels were revealed based on prior knowledge and molecular docking of hepatocyte nuclear factor 4α (HNF4α). Compared with the first quartile, mono-benzyl phthalate (MBZP) in the second quartile exhibited a decrease in total testosterone (TT) and TT/E2 (estradiol) ratio. Mono-2-ethyl-5-carboxypentyl phthalate (MECPP) in the fourth quartile showed a decrease in SHBG and TT/E2. Additionally, mono-(carboxyoctyl) phthalate and mono-(carboxynonyl) phthalate (MCNP) were negatively associated with SHBG. Each unit increase in the WQS index of MPAE mixtures was associated with 6.73 % lower SHBG levels (95 %CI: −12.80 %, −0.24 %) with mono-(3-carboxypropyl) phthalate, MCNP, MBZP, and MECPP identified as major risk factors. Interaction analyses revealed that the effects of high-risk MPAEs on SHBG were predominantly antagonistic. Molecular docking suggested that MPAEs might compete to bind tryptophan residues of HNF4α. This study provides key information to help develop the most effective phthalate interventions and improve the reproductive health of reproductive-aged women.

A whole-animal phenotypic drug screen identifies suppressors of atherogenic lipoproteins.

Lipoproteins are essential for lipid transport in all bilaterians. A single Apolipoprotein B (ApoB) molecule is the inseparable structural scaffold of each ApoB-containing lipoprotein (B-lps), which are responsible for transporting lipids to peripheral tissues. The cellular mechanisms that regulate ApoB and B-lp production, secretion, transport, and degradation remain to be fully defined. In humans, elevated levels of vascular B-lps play a causative role in cardiovascular disease. Previously, we have detailed that human B-lp biology is remarkably conserved in the zebrafish using an in vivo chemiluminescent reporter of ApoB (LipoGlo) that does not disrupt ApoB function. Thus, the LipoGlo model is an ideal system for identifying novel mechanisms of ApoB modulation and, due to the ability of zebrafish to generate many progeny, is particularly amenable to large-scale phenotypic drug screening. Here, we report a screen of roughly 3000 compounds that identified 49 unique ApoB-lowering hits. Nineteen hits passed orthogonal screening criteria. A licorice root component, enoxolone, significantly lowered B-lps only in animals that express a functional allele of the nuclear hormone receptor Hepatocyte Nuclear Factor 4α (HNF4α). Consistent with this result, inhibitors of HNF4α also reduce B-lp levels. These data demonstrate that mechanism(s) of action can be rapidly determined from a whole animal zebrafish phenotypic screen. Given the well documented role of HNF4α in human B-lp biology, these data validate the LipoGlo screening platform for identifying small molecule modulators of B-lps that play a critical role in a leading cause of worldwide mortality.

HNF4α-CDKL3 axis restricts MASLD progression by targeting FoxO1 via noncanonical phosphorylation.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a worldwide disease with a broad spectrum of symptoms. Though mild in early stages, further development of MASLD causes steatohepatitis, cirrhosis, liver cancers, and accompanied diabetes. Discovery of the critical regulators in MASLD progression hold great values in both basic and translational medicine. Herein, we identified cyclin-dependent kinase-like 3 (CDKL3) as a primary guardian against MASLD progression. Mice with liver-specific Cdkl3 ablation developed severe MASLD-related hepatic inflammation, fibrosis, and diabetes. Mechanism-wise, CDKL3 directly phosphorylates forkhead box O (FoxO)1 on an unconventional site for the ubiquitination-dependent degradation of FoxO1, thereby remarkably alleviating glycogen and lipid accumulation and essentially preventing the onset of higher MASLD stages. Moreover, hepatic CDKL3 is a direct target gene of Hepatocyte nuclear factor 4α (HNF4α). HNF4α is inhibited during MASLD, which leads to diminished CDKL3 expression. The CDKL3-mediated cross talk of HNF4α and FoxO1 hence forms a feedback loop in MASLD progression. We unearthed an alternative but critical regulatory path of FoxO1 by the HNF4α-CDKL3 axis. CDKL3 serves as a guardian against MASLD and also may function as a prognosis indicator of FoxO1 inhibitor in MASLD treatment.

Novel Regulatory Mechanisms for Expression of Drug Metabolism-related Factors

Interindividual differences in the expression and activity of drug-metabolizing enzymes, including cytochrome P450, UDP-glucuronosyltransferase, and esterases, cause variability of therapeutic effectiveness and side effects during drug treatment. Conventional research has focused on transcriptional regulation by transcription factors and nuclear receptors such as aryl hydrocarbon receptor, pregnane X receptor (PXR), constitutive androstane receptor, and hepatocyte nuclear factor 4α, as the major mechanisms causing the differences in the expression of drug-metabolizing enzymes. Recently, we have revealed that adenosine-to-inosine RNA editing and methylation of adenosine at the N6 position on RNA, two major types of posttranscriptional modification, play a pivotal role in the regulation of drug metabolism. In addition, switch/sucrose non-fermentable complex, a chromatin remodeler, is required for PXR-mediated transcriptional regulation of drug-metabolizing enzymes. This review article introduces the significance of these epitranscriptomic and epigenetic regulations as factors in determining drug metabolism potency. Further research on this link is expected to lead to a deeper understanding of interindividual differences in the therapeutic effectiveness and side effects of medicines.

Extracellular matrix protein 1 binds to connective tissue growth factor against liver fibrosis and ductular reaction.

Extracellular matrix protein 1 (ECM1) can inhibit TGFβ activation, but its antifibrotic action remains largely unknown. This study aims to investigate ECM1 function and its physical interaction with the profibrotic connective tissue growth factor (CTGF) in fibrosis and ductular reaction (DR). Ecm1 knockouts or animals that ectopically expressed this gene were subjected to induction of liver fibrosis and DR by feeding 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) or α-naphthyl-isothiocyanate (ANIT). ECM1 and CTGF were also examined in the livers of patients with alcohol-associated liver disease (ALD) or ethanol-exposed animals that were fed the western diet for 4 months in the WDA model with liver pathology resembing ALD in patients. ECM1 bound to CTGF in yeast two-hybrid systems, cultured liver cells, and cholestatic livers damaged by DDC or α-naphthyl-isothiocyanate. This interaction blocked integrin αvβ6-mediated TGFβ activation, thereby reducing fibrotic responses in vitro. ECM1 downregulation was associated with biliary CTGF induction during human ALD progression. In experimental models, Ecm1 loss enhanced susceptibility to DDC-induced cholestasis with upregulation of Ctgf, αvβ6, alpha-smooth muscle actin, procollagen type I, serum transaminase, and total bilirubin levels in germline knockouts, whereas forced expression of this gene significantly attenuated DR and biliary fibrosis after the feeding of DDC or α-naphthyl-isothiocyanate containing diets. Moreover, ectopic Ecm1 inhibited not only alcohol-associated fibrosis but also TGFβ-mediated deregulation of hepatocyte nuclear factor 4α, preventing the production of the fetal p2 promoter-driven isoforms in the WDA model. We uncover a novel antifibrotic action by ECM1 that binds CTGF and inhibits integrin αvβ6-mediated TGFβ activation. Targeting its loss has therapeutic potential for the treatment of DR and liver fibrosis in chronic conditions, such as cholangiopathy and ALD.

Is the HNF4A gene variant paradoxically associated with better prognostic in CAD patients?

Abstract Background The Hepatocyte nuclear factor 4 A (HNF4A) gene was considered to be associated with susceptibility to atherosclerosis and coronary artery disease (CAD). It encodes a protein HNF4α, a genetic transcription factor regulating the genetic expression of thousands of genes playing essential roles in glucose and lipid metabolism. Its abnormal expression is emerging as a critical factor in diabetes, dyslipidemia, and cancer. Loss of function of specific mutations could attenuate its role in CAD pathogenesis and the progression of atherosclerosis. Aim To investigate whether a genetic variant (HNF4α rs1884613 C&amp;gt;G) could be associated with a low genetic function and, paradoxically, a better prognostic in CAD patients. Methods A cohort of 1,718 patients with coronary angiography (&amp;gt;70% stenosis of at least one main coronary vessel) from the GENEMACOR Study was investigated. Thirty-three genetic variants were genotyped using TaqMan assay methodology and HNF4A rs1884613 C&amp;gt;G genotype models were individually studied regarding the occurrence of Major Adverse Cardiovascular Events (MACEs). We used bivariate analysis to evaluate genotypic and allelic differences. Multivariate Cox regression analysis estimated variables independently associated with MACE, and Kaplan-Meier estimate methodology assessed the survival. Results Of the 1,718 CAD patients with the CC wild type, 73.4% had MACE, compared with 66.5% without. CG had 25.2% compared with 30.5% without. Finally, in the GG genotype, only 1.4% had events compared with 3.0% without (p=0.004). Cox regression analysis showed that GG genotype (mutated) is significantly and independently associated with 56% of MACE protection with a hazard ratio (HR) of 0.436; p=0.014. Physical inactivity and type-2 Diabetes remained independently associated with MACE occurrence (Fig.1). Kaplan-Meier cumulative event analysis disclosed that the carriers of the GG genotype were significantly associated with a better event-free time, and CC discloses a worse event-free time (Breslow test, p=0.001) (Fig.2). Conclusions The rs1884613 genetic variant of HNF4A is associated with a better CAD prognosis. This variant could probably induce gene downregulation and HNF4A gene function loss. Modifying and modulating hepatic lipase and lipid metabolism positively affected atherosclerosis progression. Future bioactive modulators for HNF4A variants could raise the possibility that diseases involving diabetes, lipid disorders, and cancer might be amenable to pharmacologic intervention.

Hepatocyte nuclear factor 4α is a critical factor for the production of complement components in the liver.

The complement system plays an important role in biological defense as an effector to eliminate microorganisms that invade an organism and it is composed of more than 50 proteins, most of which are produced in the liver. Of these proteins, the mRNA expression of C3 and Cfb is known to be positively regulated by the nuclear receptor HNF4α. To investigate whether HNF4α regulates the complement system, we analyzed the hepatic expression of genes involved in the complement activation pathway and membrane attack complex (MAC) formation within the complement system using liver-specific Hnf4a-null mice (Hnf4aΔHep mice) and tamoxifen-induced liver-specific Hnf4a-null mice (Hnf4af/f;AlbERT2cre mice). We found that hepatic expression of many complement genes including C8a, C8b, C8g, and C9 that are involved in formation of the MAC was markedly decreased in Hnf4aΔHep mice and Hnf4af/f;AlbERT2cre mice. Furthermore, expression of C8A, C8B, and C8G was also decreased in human hepatoma cell lines in which the expression of HNF4α was suppressed, and expression of C8G and C9 was induced in a human immortalized hepatocyte cell line with forced expression of HNF4α. Transactivation of C8g and C9 was dependent on HNF4α expression of HNF4α binding sites, indicating that C8g and C9 are novel target genes of HNF4α. The results suggest that hepatic HNF4α plays an important role in regulation of the complement system, mainly MAC formation.

Low C-Reactive Protein Alleles in Hepatocyte Nuclear Factor 1A Are Associated With an Increased Risk of Cardiovascular Disease.

Rare variants in HNF1A cause both maturity onset diabetes of the young 3 (HNF1A-MODY) and reduced serum C-reactive protein (CRP) levels. Common variants of HNF1A are associated with serum CRP and type 2 diabetes mellitus (T2DM), but inconsistently with cardiovascular disease (CVD). Our study aimed to investigate the association of low CRP alleles in HNF1A with CVD and indirectly evaluate the CVD risk of HNF1A-MODY patients because of unavailability of enough cases to study their clinical outcomes. A literature search was performed using PubMed, Embase, and Cochrane Library databases from inception to December 2023. All relevant studies concerning the association of HNF1A with CRP, CVD, lipids, and T2DM were included. Odds ratios (ORs), 95% CIs, and study characteristics were extracted. Three common coding variants of HNF1A (rs1169288, rs2464196, and rs1169289) were examined. The minor alleles of these variants correlated with low CRP levels (OR 0.89; 95% CI, 0.86-0.91; OR 0.89; 95% CI, 0.88-0.91; OR 0.89; 95% CI, 0.88-0.91, respectively). Their low CRP alleles were associated with increased risk of CVD (OR 1.03; 95% CI, 1.03-1.04), higher low-density lipoprotein cholesterol levels (OR 1.07; 95% CI, 1.04-1.10), and elevated risk of T2DM (OR 1.04; 95%, CI 1.01-1.08). Our study revealed an association between low CRP alleles in HNF1A and a high CVD risk, which indicated that antidiabetic drugs with CV benefits such as glucagon-like peptide-1 receptor agonists should be recommended as a first-line choice for HNF1A-MODY.

Methyltransferase Like-3-Mediated N6-Methyladenosine Modification of Long Noncoding RNA Hepatocyte Nuclear Factor 1a Antisense RNA 1/Hepatocyte Nuclear Factor 4a Antisense RNA 1 Regulates Cytochrome P450 Enzyme Expression.

Interindividual variations in the expression and activity of cytochrome P450 enzymes (CYPs) led to lower therapeutic efficacy or adverse drug events. We previously demonstrated that CYPs are regulated by the long noncoding RNAs (lncRNAs) hepatocyte nuclear factor 1a antisense RNA 1 (HNF1A-AS1) and HNF4A-AS1 via transcription factors (TFs) including hepatocyte nuclear factor 1a (HNF1A), hepatocyte nuclear factor 4a (HNF4A), and pregnane X receptor (PXR). However, the upstream mechanisms regulating HNF1A-AS1 and HNF4A-AS1 are poorly understood. N6-methyladenosine (m6A) is a prevalent epitranscriptomic modification in mammalian RNA. Therefore, the aim of this study was to investigate whether m6A modification regulates the expression of HNF1A-AS1 and HNF4A-AS1 and affects CYP expression in HepG2 and Huh7 cells. The methyltransferase-like 3 (METTL3) inhibitor, STM2457, significantly suppressed the expression of HNF1A-AS1 and induced HNF4A-AS1 expression. Consistent with this, a loss-of-function assay of METTL3 in the cell lines resulted in the downregulation of HNF1A-AS1 and its downstream HNF1A, PXR, and CYPs at the RNA level, as well as the downregulation of some CYPs proteins, and upregulation of HNF4A-AS1. The results of gain-of-function experiments showed the opposite trend. Mechanistically, subsequent RNA stability experiments confirmed that METTL3 affected the stability of both lncRNAs, but in opposite ways; that is, METTL3 reduced HNF1A-AS1 stability and increased HNF4A-AS1 stability. Rescue experiments confirmed that the regulation of METTL3 on TFs and CYPs may require the involvement of these two lncRNAs. Altogether, our study demonstrates that METTL3 is involved in TFs-mediated CYP expression by affecting HNF1A-AS1/HNF4A-AS1 stability. SIGNIFICANCE STATEMENT: Although the impact of long noncoding RNAs (lncRNAs) including hepatocyte nuclear factor 1a antisense RNA 1 (HNF1A-AS1) and hepatocyte nuclear factor 4a antisense RNA 1 (HNF4A-AS1) on the downstream transcription factor (TF) and cytochrome P450 enzyme (CYP) expression is well studied, the upstream regulation of these two lncRNAs by methyltransferase-like 3 (METTL3) remains unexplored. This study reveals that METTL3 is involved in the regulation of lncRNA-TF-CYP expression by affecting the stability of HNF1A-AS1 and HNF4A-AS1 in HepG2 and Huh7 cells.

The biochemistry of melanogenesis: an insight into the function and mechanism of melanogenesis-related proteins.

Melanin is an amino acid derivative produced by melanocyte through a series of enzymatic reactions using tyrosinase as substrate. Human skin and hair color is also closely related to melanin, so understanding the mechanisms and proteins that produce melanin is very important. There are many proteins involved in the process of melanin expression, For example, proteins involved in melanin formation such as p53, HNF-1α (Hepatocyte nuclear factor 1α), SOX10 (Sry-related HMg-Box gene 10) and pax3 (paired box gene 3), MC1R(Melanocortin 1 Receptor), MITF (Microphthalmia-associated transcription factor), TYR (tyrosinase), TYRP1 (tyrosinase-related protein-1), TYRP2 (tyrosinase-related protein-2), and can be regulated by changing their content to control the production rate of melanin. Others, such as OA1 (ocular albinism type 1), Par-2 (protease-activated receptor 2) and Mlph (Melanophilin), have been found to control the transfer rate of melanosomes from melanocytes to keratinocytes, and regulate the amount of human epidermal melanin to control the depth of human skin color. In addition to the above proteins, there are other protein families also involved in the process of melanin expression, such as BLOC, Rab and Rho. This article reviews the origin of melanocytes, the related proteins affecting melanin and the basic causes of related gene mutations. In addition, we also summarized the active ingredients of 5 popular whitening cosmetics and their mechanisms of action.

Bifunctional silver-metal organic gels with catalytic and electrochemiluminescence properties applied for ratio detection of I27L gene

The rate of maturity-onset diabetes of the young (MODY) is significantly increased by the common I27L gene variant of the hepatocyte nuclear factor-1α (HNF1A), hence achieving sensitive and precise I27L gene detection is the focus of early monitoring and diagnosis of HNF1A-MODY. In this study, we developed a silver-metal organic gels (Ag MOGs)/ K2S2O8-O2 system-based electrochemiluminescence resonance energy transfer (ECL-RET) ratio biosensor for detecting the I27L gene. The novel Ag MOGs were synthesized by simply mixing Ag+ and Luminol at ambient temperature. On the one hand, Ag MOGs could generate excellent anodic ECL signals in phosphate buffer without requiring exogenous co-reactants, which were derived from the Luminol ligand. On the other hand, Ag MOGs facilitated the electrocatalytic reduction of K2S2O8 by providing stable catalytic active sites and enhancing electron transfer rates, thereby leading to enhanced cathodic ECL emission from K2S2O8-O2. We constructed an ECL-RET ratio biosensor utilizing a DNA walker cycle amplification strategy. The biosensor leveraged the anodic ECL emission from the Ag MOGs/K2S2O8-O2 system as a donor and Atto 425 as a receptor, achieving ultra-sensitive detection of the I27L gene within a linear range of 100 amol/L to 100 pmol/L, and featuring a detection limit of 72 amol/L. Therefore, a direct synthesis technique of bifunctional materials with catalysis and electrochemiluminescence has been developed. Additionally, the ECL-RET ratio biosensor provided a universal platform for the detection of diabetes subtypes.

The cholesterol-lowering effects and mechanisms of novel milk casein-derived peptides in hyperlipidemia and hypercholesterol mice

Food-derived cholesterol-lowering peptides have the practical benefit of inhibiting lipid absorption and regulating systemic cholesterol homeostasis. This work aimed to explore the antihyperlipidemia function of milk casein-derived peptides Leu-Gln-Pro-Glu (LQPE), Val-Leu-Pro-Val-Pro-Gln (VLPVPQ), and Val-Ala-Pro-Phe-Pro-Glu (VAPFPE) and investigated whether the function of these peptides affected the gut microbiome. According to the experimental findings, lipid metabolism disorder in hyperlipidemia mice was improved to various degrees by all three peptides, which dramatically lowered the levels of low-density lipoprotein cholesterol (LDL-C) and triglyceride (TG) in the serum and inhibited the buildup of lipids in the liver and the development of steatosis. VAPFPE was found to reduce intestinal cholesterol absorption and the formation of cholesterol esters by inhibiting hepatocyte nuclear factor 4α (HNF4α), niemann-pick C1-like 1 (NPC1L1), and acetyl coenzyme A acetyltransferase 2 (ACAT2) expression and increase intestinal cholesterol efflux through up-regulation of ATP-binding cassette transporter G8 (ABCG8). VAPFPE also maintained cholesterol homeostasis by up-regulating liver low-density lipoprotein receptor (LDL-R) expression. The 16S rRNA analysis revealed that all three peptides improve the gut microbial composition, and VAPFPE specifically encouraged a rise in the proportional abundance of Bifidobacterium. The results shed light on the potential applications of bioactive peptides as functional health foods for lowering cholesterol.

A novel heterozygous likely pathogenic SLC5A2 variant in a diabetic patient with glucosuria and aminoaciduria.

Familial renal glucosuria (FRG) is a rare renal tubular disorder characterized by increased urinary glucose excretion despite normoglycemia. It is most commonly caused by pathogenic variants in the solute carrier family V member 2 (SLC5A2) gene. This gene encodes the sodium-glucose cotransporter 2, crucial for glucose reabsorption. We report the case of a 44-year-old male referred to the endocrinology outpatient clinic for unexplained glucosuria despite well-controlled diabetes mellitus with metformin and gliclazide therapy. His main complaints were nocturia and an unintentional 5 kg weight loss in 1 year. A 24-h urinary collection revealed overt glucosuria (23.3 g/1.73 m2/24 h), generalized aminoaciduria, and increased uric acid excretion (fractional excretion: 6.4%). Whole-exome sequencing revealed a novel heterozygous c.469-1G>A likely pathogenic variant in the SLC5A2 gene. Specific analysis of the maturity-onset diabetes of the young type (MODY) gene panel showed no pathogenic variants in the hepatocyte nuclear factor-1A (HNF-1A; MODY3) nor in other MODY-associated genes. We assume that the association of glucosuria, aminoaciduria, and increased uric acid excretion can be explained by the combination of diabetes and the likely pathogenic SLC5A2 variant in this patient. In conclusion, we describe a well-controlled diabetic patient with FRG, associated with a novel heterozygous c.469-1G>A likely pathogenic variant in the SLC5A2 gene. The diagnosis of a renal tubular disorder should be considered in patients with unexplained glucosuria and diabetes mellitus, especially if the latter is well controlled. FRG usually presents with glucosuria but may be associated with generalized aminoaciduria and hyperuricosuria. Genetic analysis should be considered in patients with young-onset diabetes and glucosuria, particularly with a positive family history.

Novel role of MHC class II transactivator in hepatitis B virus replication and viral counteraction.

The major histocompatibility class II (MHC II) transactivator, known as CIITA, is induced by Interferon gamma (IFN-γ) and plays a well-established role in regulating the expression of class II MHC molecules in antigen-presenting cells. Primary human hepatocytes (PHH) were isolated via therapeutic hepatectomy from two donors. The hepatocellular carcinoma (HCC) cell lines HepG2 and Huh7 were used for the mechanistic study, and HBV infection was performed in HepG2-NTCP cells. HBV DNA replication intermediates and secreted antigen levels were measured using Southern blotting and ELISA, respectively. We identified a non-canonical function of CIITA in the inhibition of hepatitis B virus (HBV) replication in both HCC cells and patient-derived PHH. Notably, in vivo experiments demonstrated that HBV DNA and secreted antigen levels were significantly decreased in mice injected with the CIITA construct. Mechanistically, CIITA inhibited HBV transcription and replication by suppressing the activity of HBV-specific enhancers/promoters. Indeed, CIITA exerts antiviral activity in hepatocytes through ERK1/2-mediated down-regulation of the expression of hepatocyte nuclear factor 1α (HNF1α) and HNF4α, which are essential factors for virus replication. In addition, silencing of CIITA significantly abolished the IFN-γ-mediated anti-HBV activity, suggesting that CIITA mediates the anti-HBV activity of IFN-γ to some extent. HBV X protein (HBx) counteracts the antiviral activity of CIITA via direct binding and impairing its function. Our findings reveal a novel antiviral mechanism of CIITA that involves the modulation of the ERK pathway to restrict HBV transcription. Additionally, our results suggest the possibility of a new immune avoidance mechanism involving HBx.

Tripartite motif 8 promotes the progression of hepatocellular carcinoma via mediating ubiquitination of HNF1α

Tripartite motif 8 (TRIM8) is an E3 ligase that plays dual roles in various tumor types. The biological effects and underlying mechanism of TRIM8 in hepatocellular carcinoma (HCC) remain unknown. Hepatocyte nuclear factor 1α (HNF1α) is a key transcriptional factor that plays a significant role in regulating hepatocyte differentiation and liver function. The reduced expression of HNF1α is a critical event in the development of HCC, but the underlying mechanism for its degradation remains elusive. In this study, we discovered that the expression of TRIM8 was upregulated in HCC tissues, and was positively correlated with aggressive tumor behavior of HCC and shorter survival of HCC patients. Overexpression of TRIM8 promoted the proliferation, colony formation, invasion, and migration of HCC cells, while TRIM8 knockdown or knockout exerted the opposite effects. RNA sequencing revealed that TRIM8 knockout suppresses several cancer-related pathways, including Wnt/β-catenin and TGF-β signaling in HepG2 cells. TRIM8 directly interacts with HNF1α, promoting its degradation by catalyzing polyubiquitination on lysine 197 in HCC cells. Moreover, the cancer-promoting effects of TRIM8 in HCC were abolished by the HNF1α-K197R mutant in vitro and in vivo. These data demonstrated that TRIM8 plays an oncogenic role in HCC progression through mediating the ubiquitination of HNF1α and promoting its protein degradation, and suggests targeting TRIM8-HNF1α may provide a promising therapeutic strategy of HCC.

Molecular mechanism of HNF-1A-mediated HNF4A gene regulation and promoter-driven HNF4A-MODY diabetes.

Monogenic diabetes is a gateway to precision medicine through molecular mechanistic insight. Hepatocyte nuclear factor 1A (HNF-1A) and HNF-4A are transcription factors that engage in crossregulatory gene transcription networks to maintain glucose-stimulated insulin secretion in pancreatic β cells. Variants in the HNF1A and HNF4A genes are associated with maturity-onset diabetes of the young (MODY). Here, we explored 4 variants in the P2-HNF4A promoter region: 3 in the HNF-1A binding site and 1 close to the site, which were identified in 63 individuals from 21 families of different MODY disease registries across Europe. Our goal was to study the disease causality for these variants and to investigate diabetes mechanisms on the molecular level. We solved a crystal structure of HNF-1A bound to the P2-HNF4A promoter and established a set of techniques to probe HNF-1A binding and transcriptional activity toward different promoter variants. We used isothermal titration calorimetry, biolayer interferometry, x-ray crystallography, and transactivation assays, which revealed changes in HNF-1A binding or transcriptional activities for all 4 P2-HNF4A variants. Our results suggest distinct disease mechanisms of the promoter variants, which can be correlated with clinical phenotype, such as age of diagnosis of diabetes, and be important tools for clinical utility in precision medicine.