Tcf7l2 in hepatocytes regulates de novo lipogenesis in diet-induced non-alcoholic fatty liver disease in mice

TCF7l2 Regulates Fatty Acid Chain Elongase HACD3 during Lipid-Induced Stress

The transcriptional regulation of metabolic genes is crucial for maintaining metabolic homeostasis under cellular stress conditions. Transcription factor 7-like 2 (TCF7l2 or TCF4) is associated with type 2 diabetes (T2D) and functions as a transcription factor for various gluconeogenic genes. T2D often coexists with metabolic dysfunction-associated steatotic liver disease (MASLD) due to common underlying mechanisms and shared risk factors such as insulin resistance and obesity. This study demonstrates the transcriptional regulation of one of the important fatty acid chain elongases implicated in T2D, HACD3 (encoded by PTPLAD1 gene), under palmitic acid (PA)-induced stress conditions. We observed that TCF7l2 is associated with histone H3K4me3-binder protein TCF19 and is corecruited to the promoter of PTPLAD1. Upon PA treatment, the TCF19-TCF7l2 complex dissociates from the lipid chain elongase gene due to the reduced level of H3K4me3 enrichment, leading to PTPLAD1 activation. Remarkably, gene expression analysis from the PA-injected mice and NAFLD patients indicates an anticorrelation whereby reduced TCF7l2 expression enhances HACD3-mediated chain elongation and triglyceride production, thereby promoting the development of MASLD. Our findings delineate that the epigenetic mechanism of activation of lipid chain elongase genes mediated by TCF7l2 in concert with TCF19 has important implications in metabolic disorders.

The Spatial Transcriptional Activity of Hepatic TCF7L2 Regulates Zonated Metabolic Pathways that Contribute to Liver Fibrosis

The molecular mechanisms regulating the zonal distribution of metabolism in liver are incompletely understood. Here we use single nuclei genomics techniques to examine the spatial transcriptional function of transcription factor 7-like 2 (TCF7L2) in mouse liver, and determine the consequences of TCF7L2 transcriptional inactivation on the metabolic architecture of the liver and the function of zonated metabolic pathways. We report that while Tcf7l2 mRNA expression is ubiquitous across the liver lobule, accessibility of the consensus TCF/LEF DNA binding motif is restricted to pericentral (PC) hepatocytes in zone 3. In mice expressing functionally inactive TCF7L2 in liver, PC hepatocyte-specific gene expression is absent, which we demonstrate promotes hepatic cholesterol accumulation, impaired bile acid synthesis, disruption to glutamine/glutamate homeostasis and pronounced dietary-induced hepatic fibrosis. In summary, TCF7L2 is a key regulator of hepatic zonal gene expression and regulates several zonated metabolic pathways that may contribute to the development of fibrotic liver disease.

Resveratrol improves gasdermin D-mediated pyroptosis of vascular endothelial cells induced by a high-fat diet and palmitic acid possibly via the SIRT1-p66Shc-NLRP3 pathway

Resveratrol (RSV) ameliorates endothelial dysfunction (ED) primarily through sirtuin 1 (SIRT1). Increasing evidence shows pyroptosis as a novel mechanism in palmitic acid (PA)-induced ED. p66Shc is an adaptor protein involved in oxidative stress. However, whether RSV attenuates the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome via p66Shc remains elusive. This study aims to evaluate whether the antipyroptotic effect of RSV and the SIRT1 inhibitor EX527 are related to p66Shc. High-fat diet (HFD) induced obesity in mice, and RSV was administered intragastrically with 400mg/kg/d for 22 successive weeks. The serum levels of interleukin-1β (IL-1β) and IL-18 were analyzed, and the expression of related proteins were assayed with immunohistochemistry in the thoracic aorta. human umbilical vein endothelial cells (HUVECs) were induced by PA, then treated with RSV and EX527 respectively, lactate dehydrogenase (LDH) release, reactive oxygen species (ROS) levels, mitochondrial membrane potential (MMP) and expression of p66Shc, NLRP3, GSDMD and pyroptosis-related genes were assayed. RSV administration ameliorated endothelial cell pyroptosis by decreasing serum IL-1β and IL-18, the expression of NLRP3, p66Shc, and gasdermin D (GSDMD), and increasing the expression of SIRT1 in the HFD-treated thoracic aorta. PA promoted GSDMD-mediated endothelial cell pyroptosis by ROS production, LDH release, decreased MMP and SIRT1 expression, increased expression of p66Shc and activation of the NLRP3 inflammasome in a dose-dependent manner. RSV attenuated PA-induced pyroptosis, whereas EX527 reversed the antipyroptotic effect of RSV in PA-treated HUVECs. Our results suggested a new mechanism that RSV improves PA-induced pyroptosis in endothelial cells via the SIRT1-p66Shc-NLRP3 pathway.

CC Genotype at TCF7L2 Diabetes Risk Locus rs7903146 Directs a Coordinated Fatty Acid Response to a Mediterranean Diet Intervention: A Randomized Controlled Trial

INTRODUCTION

Previous studies identified genetic links between the TCF7L2 C/T variant rs7903146, type 2 diabetes (T2D), and obesity. We wished to deepen our understanding of how specific diets interact with this variant to affect blood metabolites, an aspect not previously investigated. Hence, we conducted a controlled study where individuals with different genotypes followed a Mediterranean (Med) or low-fat (LF) diet for 1 week.

METHODS

Participants were recruited from the Boston, MA (USA) area. Anthropometric and clinical measures were taken. Genotypes at rs7903146 were ascertained, with homozygous carriers of the more common and protective CC or risk TT genotype invited to participate. Participants followed both diets (LF or Med) for 1 week with ∼10 days' washout between diets. Blood samples taken at the beginning and end of each diet period underwent metabolomics analysis using nuclear magnetic resonance spectroscopy. We evaluated how the diet affected different metabolites based on genetic profile.

RESULTS

The cohort of 35 persons was 43% female, aged 18-70 y, with BMI between 26.4 and 33.9 kg/m2. Focusing on fatty acids (FAs) and other lipid metabolic factors (n = 23), we observed a greater number and stronger correlations among these factors in the CC genotype-Med diet group than in the other three genotype-diet combinations. An aggregate of 11 factors, each negatively correlating with delta-saturated fatty acids (SFA), showed a significant genotype-Med diet interaction on delta-SFA in CC individuals on the Med diet (p = 0.0046). A similar genotype-Med diet interaction was observed for delta-monounsaturated fatty acids (p = 0.0078). These interactions were not statistically significant at the end of the LF intervention.

CONCLUSION

Our findings suggest that the Med diet has a stronger influence on regulating lipid factors in individuals with the CC genotype at the TCF7L2 variant rs7903146. This diet-genotype interaction may have significant implications for understanding the inter-individual variation of metabolic response on specific dietary regimens.

The transcription factor TCF4 regulates the miR-494-3p/THBS1 axis in the fibrosis of pathologic scars

BACKGROUND

The fibrosis of pathologic scar (PS) is formed by the excessive deposition of extracellular matrix, resulting in an abnormal scar. Recent clinical tests have indicated that the regulation of PS fibroblast cells (PSF cells) proliferation can serve as an intervention measure for PS. Our work aimed to elucidate the specific mechanism of action of TCF4 on the progression of PS fibrosis.

METHODS

Our study used qRT-PCR and Western blot to search for the expression of key proteins in PS clinical samples and cells. Transwell, CCK-8, and wound scratch assays were employed to analyze the proliferation and migration of PSF cells. CHIP, dual-luciferase reporter experiments, and bio-informatics analysis were used to analyze the interactions between molecules.

RESULTS

The analysis of PS clinical samples confirmed a positive correlation between TCF4 and miR-494-3p. This regulatory mechanism was related to the progression of PS. We verified that the overexpression of miR-494-3p or the knockdown of THBS1 both suppressed the proliferation and migration of PSF cells. Furthermore, we also confirmed the binding relationships between TCF4, miR-494-3p, and THBS1. Simultaneously, we verified the existence of the TCF4/miR-494-3p/THBS1 regulatory network in PS. This regulatory process affects the development of PS fibrosis.

CONCLUSION

Our study results indicate that TCF4, miR-494-3p, and THBS1 are abnormally expressed in PS. TCF4 increases the proliferation and migration ability of PSF cells through the miR-494-3p/THBS1 signaling pathway, which promotes the fibrosis of PS.

De novo lipid synthesis in cardiovascular tissue and disease

Most tissues have the capacity for endogenous lipid synthesis. A crucial foundational pathway for lipid synthesis is de novo lipid synthesis (DNL), a ubiquitous and complex metabolic process that occurs at high levels in the liver, adipose and brain tissue. Under normal physiological conditions, DNL is vital in converting excess carbohydrates into fatty acids. DNL is linked to other pathways, including the endogenous synthesis of phospholipids and sphingolipids. However, abnormal lipid synthesis can contribute to various pathologies and clinical conditions. Experimental studies involving dietary restriction and in vivo genetic modifications provide compelling evidence demonstrating the significance of lipid synthesis in maintaining normal cardiovascular tissue function. Similarly, clinical investigations suggest altered lipid synthesis can harm cardiac and arterial tissues, thereby influencing cardiovascular disease (CVD) development and progression. Consequently, there is increased interest in exploring pharmacological interventions that target lipid synthesis metabolic pathways as potential strategies to alleviate CVD. Here we review the physiological and pathological impact of endogenous lipid synthesis and its implications for CVD. Since lipid synthesis can be targeted pharmacologically, enhancing our understanding of the molecular and biochemical mechanisms underlying lipid generation and cardiovascular function may prompt new insights into CVD and its treatment.

Single-nucleus transcriptional profiling reveals TCF7L2 as a key regulator in adipogenesis in goat skeletal muscle development

Intramuscular adipogenesis plays an important role in muscle development, which determines the quality of goat meat. However, its underlying cellular and molecular mechanisms remain poorly understood. In this study, we provided detailed cellular atlases of goat longissimus dorsi during muscle development at single-nucleus resolution, and identified the subpopulations of fibroblasts/fibro-adipogenic progenitors (FAPs) and muscle satellite cell (MuSC), as well as the differentiation trajectory of FAPs subpopulations. Cellular ligand-receptor interaction analysis revealed enriched BMP and IGF pathways implicated in within-tissue crosstalk centered around FAPs. Through single-nucleus gene regulatory network analysis and in vitro interference verification, we found that TCF7L2 was a critical transcriptional factor (TF) in early adipogenesis in skeletal muscle. Overall, our work reveals the cellular intricacies and diversity of goat longissimus dorsi during muscle development, implementing insights into the critical roles of BMP, IGF pathways and TCF7L2 TF in intramuscular adipogenesis.

Transcription factor 7 like 2 promotes metastasis in hepatocellular carcinoma via NEDD9-mediated activation of AKT/mTOR signaling pathway

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors of the digestive system, and the exact mechanism of HCC is still unclear. Transcription factor 7 like 2 (TCF7L2) plays a pivotal role in cell proliferation and stemness maintenance. However, the exact mechanism of TCF7L2 in HCC remains unclear.

METHODS

Clinical samples and public databases were used to analyze the expression and prognosis of TCF7L2 in HCC. The function of TCF7L2 in HCC was studied in vitro and in vivo. ChIP and luciferase assays were used to explore the molecular mechanism of TCF7L2. The relationship between TCF7L2 and NEDD9 was verified in HCC clinical samples by tissue microarrays.

RESULTS

The expression of TCF7L2 was upregulated in HCC, and high expression of TCF7L2 was associated with poor prognosis of HCC patients. Overexpression of TCF7L2 promoted the metastasis of HCC in vitro and in vivo, while Knockdown of TCF7L2 showed the opposite effect. Mechanically, TCF7L2 activated neural precursor cell expressed developmentally downregulated protein 9 (NEDD9) transcription by binding to the -1522/-1509 site of the NEDD9 promoter region, thereby increasing the phosphorylation levels of AKT and mTOR. The combination of TCF7L2 and NEDD9 could distinguish the survival of HCC patients.

CONCLUSIONS

This study demonstrated that TCF7L2 promotes HCC metastasis by activating AKT/mTOR pathway in a NEDD9-dependent manner, suggesting that potential of TCF7L2 and NEDD9 as prognostic markers and therapeutic targets for HCC.

Genetic variation is a key determinant of chromatin accessibility and drives differences in the regulatory landscape of C57BL/6J and 129S1/SvImJ mice

Most common genetic variants associated with disease are located in non-coding regions of the genome. One mechanism by which they function is through altering transcription factor (TF) binding. In this study, we explore how genetic variation is connected to differences in the regulatory landscape of livers from C57BL/6J and 129S1/SvImJ mice fed either chow or a high-fat diet. To identify sites where regulatory variation affects TF binding and nearby gene expression, we employed an integrative analysis of H3K27ac ChIP-seq (active enhancers), ATAC-seq (chromatin accessibility) and RNA-seq (gene expression). We show that, across all these assays, the genetically driven (i.e. strain-specific) differences in the regulatory landscape are more pronounced than those modified by diet. Most notably, our analysis revealed that differentially accessible regions (DARs, N = 29635, FDR < 0.01 and fold change > 50%) are almost always strain-specific and enriched with genetic variation. Moreover, proximal DARs are highly correlated with differentially expressed genes. We also show that TF binding is affected by genetic variation, which we validate experimentally using ChIP-seq for TCF7L2 and CTCF. This study provides detailed insights into how non-coding genetic variation alters the gene regulatory landscape, and demonstrates how this can be used to study the regulatory variation influencing TF binding.

Mechanisms and Physiological Roles of Polymorphisms in Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) is a significant pregnancy complication linked to perinatal complications and an elevated risk of future metabolic disorders for both mothers and their children. GDM is diagnosed when women without prior diabetes develop chronic hyperglycemia due to β-cell dysfunction during gestation. Global research focuses on the association between GDM and single nucleotide polymorphisms (SNPs) and aims to enhance our understanding of GDM's pathogenesis, predict its risk, and guide patient management. This review offers a summary of various SNPs linked to a heightened risk of GDM and explores their biological mechanisms within the tissues implicated in the development of the condition.

Association between nonalcoholic fatty liver disease and increased glucose-to-albumin ratio in adults without diabetes

Background

Nonalcoholic fatty liver disease (NAFLD) affects approximately 30% of individuals globally. Both serum glucose and albumin were demonstrated to be potential markers for the development of NAFLD. We hypothesized that the risk of NAFLD may be proportional to the glucose-to-albumin ratio (GAR).

Methods

Based on information from the National Health and Nutrition Examination Survey (NHANES) 1999-2018, it was determined that GAR was associated with an increased risk of NAFLD and liver fibrosis utilizing weighted multivariable logistic regression. Participants with a fatty liver index (FLI) over 60 were identified with NAFLD, and those with an NAFLD fibrosis score (NFS) >0.676 with evidence of NAFLD were labeled with advanced hepatic fibrosis (AHF). The liver biopsy was utilized to verify the relationship between GAR and FLD in our center cohort. Mendelian randomization analysis investigated the genetic relationship between GAR and NAFLD.

Results

Of 15,534 eligible participants, 36.4% of participants were identified as NAFLD without AHF. GAR was positively correlated with the probability of NAFLD following full adjustment for possible variables (OR = 1.53, 95% CI: 1.39-1.67). It was confirmed that patients with NAFLD and AHF had an inferior prognosis. The relationship between GAR and NFS was favorable (R = 0.46, P< 0.0001), and NAFLD patients with a higher GAR tended to develop poor survival. In our center cohort, the association between GAR and NAFLD was verified.

Conclusion

Among participants without diabetes, greater GAR was linked to higher risks of NAFLD. In addition, NAFLD patients with higher GAR tended to develop liver fibrosis and adverse outcomes.

Cellular heterogeneity and plasticity during NAFLD progression

Nonalcoholic fatty liver disease (NAFLD) is a progressive liver disease that can progress to nonalcoholic steatohepatitis (NASH), NASH-related cirrhosis, and hepatocellular carcinoma (HCC). NAFLD ranges from simple steatosis (or nonalcoholic fatty liver [NAFL]) to NASH as a progressive form of NAFL, which is characterized by steatosis, lobular inflammation, and hepatocellular ballooning with or without fibrosis. Because of the complex pathophysiological mechanism and the heterogeneity of NAFLD, including its wide spectrum of clinical and histological characteristics, no specific therapeutic drugs have been approved for NAFLD. The heterogeneity of NAFLD is closely associated with cellular plasticity, which describes the ability of cells to acquire new identities or change their phenotypes in response to environmental stimuli. The liver consists of parenchymal cells including hepatocytes and cholangiocytes and nonparenchymal cells including Kupffer cells, hepatic stellate cells, and endothelial cells, all of which have specialized functions. This heterogeneous cell population has cellular plasticity to adapt to environmental changes. During NAFLD progression, these cells can exert diverse and complex responses at multiple levels following exposure to a variety of stimuli, including fatty acids, inflammation, and oxidative stress. Therefore, this review provides insights into NAFLD heterogeneity by addressing the cellular plasticity and metabolic adaptation of hepatocytes, cholangiocytes, hepatic stellate cells, and Kupffer cells during NAFLD progression.