Obesity-Induced Upregulation of ZBTB7A Promotes Lipid Accumulation through SREBP1

Mechanism of Metabolic Dysfunction-associated Steatotic Liver Disease: Important role of lipid metabolism

Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as non-alcoholic fatty liver disease, has a high global prevalence and can progress to metabolic dysfunction-associated steatohepatitis, cirrhosis, and hepatocellular carcinoma. The pathogenesis of MASLD is primarily driven by disturbances in hepatic lipid metabolism, involving six key processes: increased hepatic fatty acid uptake, enhanced fatty acid synthesis, reduced oxidative degradation of fatty acids, increased cholesterol uptake, elevated cholesterol synthesis, and increased bile acid synthesis. Consequently, maintaining hepatic lipid metabolic homeostasis is essential for effective MASLD management. Numerous novel molecules and Chinese proprietary medicines have demonstrated promising therapeutic potential in treating MASLD, primarily by inhibiting lipid synthesis and promoting lipid oxidation. In this review, we summarized recent research on MASLD, elucidated the molecular mechanisms by which lipid metabolism disorders contribute to MASLD pathogenesis, and discussed various lipid metabolism-targeted therapeutic approaches for MASLD.

CD36 restricts lipid-associated macrophages accumulation in white adipose tissues during atherogenesis

Visceral white adipose tissues (WAT) regulate systemic lipid metabolism and inflammation. Dysfunctional WAT drive chronic inflammation and facilitate atherosclerosis. Adipose tissue-associated macrophages (ATM) are the predominant immune cells in WAT, but their heterogeneity and phenotypes are poorly defined during atherogenesis. The scavenger receptor CD36 mediates ATM crosstalk with other adipose tissue cells, driving chronic inflammation. Here, we combined the single-cell RNA sequencing technique with cell metabolic and functional assays on major WAT ATM subpopulations using a diet-induced atherosclerosis mouse model (Apoe-null). We also examined the role of CD36 using Apoe/Cd36 double-null mice. Based on transcriptomics data and differential gene expression analysis, we identified a previously undefined group of ATM displaying low viability and high lipid metabolism and labeled them as "unhealthy macrophages". Their phenotypes suggest a subpopulation of ATM under lipid stress. We also identified lipid-associated macrophages (LAM), which were previously described in obesity. Interestingly, LAM increased 8.4-fold in Apoe/Cd36 double-null mice on an atherogenic diet, but not in Apoe-null mice. The increase in LAM was accompanied by more ATM lipid uptake, reduced adipocyte hypertrophy, and less inflammation. In conclusion, CD36 mediates a delicate balance between lipid metabolism and inflammation in visceral adipose tissues. Under atherogenic conditions, CD36 deficiency reduces inflammation and increases lipid metabolism in WAT by promoting LAM accumulation.

The inhibitory effects of Xiao-Gao-Jiang-Zhuo-containing serum on adipogenesis in 3T3-L1 preadipocytes

BACKGROUND

Obesity and related metabolic diseases are becoming a worldwide epidemic, leading to increased mortality and heavy medical costs. Our Chinese herbal formula Xiao-Gao-Jiang-Zhuo (XGJZ) has remarkable effects on curing obese patients in the clinic, but the cellular and molecular basis remains unknown. This study aimed to reveal the molecular mechanism involved in adipogenesis in vitro.

METHODS

Chinese herbal formula XGJZ-containing serum was prepared from XGJZ-treated obesity model rats. The function of XGJZ-containing serum was validated in 3T3-L1 preadipocytes. Oil O staining was performed to determine intracellular lipid accumulation in differentiated 3T3-L1 cells. The expression of pro-adipogenic transcription factors was measured to further validate the adipogenesis of 3T3-L1 adipocytes. The contents of triglyceride (TG), free fatty acid (FFA), and glycerin, along with the activities of lipid metabolism-related enzymes (including FAT, FATP1, DGAT, GPAT, ATGL, and HSL) were measured to study the lipogenesis in 3T3-L1 adipocytes.

RESULTS

XGJZ-containing serum inhibited 3T3-L1 differentiation, decreased intracellular lipid accumulation, and suppressed the expression of pro-adipogenic transcription factors in differentiated 3T3-L1 cells. The contents of TG, FFA, and glycerin were decreased when treated with XGJZ-containing serum, which also modulated lipid metabolism-related enzyme activities. The activities of fatty acid transporters (FAT, FATP1) and lipid mobilization enzymes (ATGL, HSL) were promoted, while activities of triglyceride biosynthesis enzymes (DGAT, GPAT) were attenuated in differentiated 3T3-L1 cells.

CONCLUSION

XGJZ-containing serum has inhibitory effects on adipogenesis in 3T3-L1 preadipocytes, affirming the effect of XGJZ in treating obesity. It provides evidence for the mechanism of obesity.

Sterol regulatory element binding transcription factor 1 promotes proliferation and migration in head and neck squamous cell carcinoma

Background

Sterol-regulatory element-binding protein 1 (SREBP1) is a transcription factor involved in lipid metabolism that is encoded by sterol regulatory element binding transcription factor 1(SREBF1). SREBP1 overexpression is associated with the progression of several human tumors; however, the role of SREBP1 in head and neck squamous cell carcinoma (HNSC) remains unclear.

Methods

SREBF1 expression in pan-cancer was analyzed using the Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) data, and the association between SREBF1 expression and clinical characteristics of HNSC patients was examined using the UALCAN database. Enrichment analysis of SREBF1-related genes was performed using the Cluster Profiler R package. TCGA database was used to investigate the relationship between immune cell infiltration and SREBF1 expression. CCK-8, flow cytometry, and wound healing assays were performed to investigate the effect of SREBF1 knockdown on the proliferation and migration of HNSC cells.

Results

SREBF1 was significantly upregulated in several tumor tissues, including HNSC, and SREBF1 overexpression was positively correlated with sample type, cancer stage, tumor grade, and lymph node stage in HNSC patients. Gene enrichment analysis revealed that SREBF1 is associated with DNA replication and homologous recombination. SREBF1 upregulation was positively correlated with the infiltration of cytotoxic cells, B cells, T cells, T helper cells, and NK CD56 bright cells in HNSC. Knockdown of SREBF1 inhibited the proliferation and migration of HNSC cells (Hep2 and TU212) and induced apoptosis by downregulating the expression of steroidogenic acute regulatory protein-related lipid transfer 4 (STARD4).

Conclusions

SREBF1 may promote HNSC proliferation, migration and inhibit apoptosis by upregulating STARD4 and affecting the level of immune cell infiltration.

Target Deconvolution of Fenofibrate in Nonalcoholic Fatty Liver Disease Using Bioinformatics Analysis

Background

Nonalcoholic fatty liver disease (NAFLD) is a prevalent form of liver damage, affecting ~25% of the global population. NAFLD comprises a spectrum of liver pathologies, from hepatic steatosis to nonalcoholic steatohepatitis (NASH), and may progress to liver fibrosis and cirrhosis. The presence of NAFLD correlates with metabolic disorders such as hyperlipidemia, obesity, blood hypertension, cardiovascular, and insulin resistance. Fenofibrate is an agonist drug for peroxisome proliferator-activated receptor alpha (PPARα), used principally for treatment of hyperlipidemia. However, fenofibrate has recently been investigated in clinical trials for treatment of other metabolic disorders such as diabetes, cardiovascular disease, and NAFLD. The evidence to date indicates that fenofibrate could improve NAFLD. While PPARα is considered to be the main target of fenofibrate, fenofibrate may exert its effect through impact on other genes and pathways thereby alleviating, and possibly reversing, NAFLD. In this study, using bioinformatics tools and gene-drug, gene-diseases databases, we sought to explore possible targets, interactions, and pathways involved in fenofibrate and NAFLD.

Methods

We first determined significant protein interactions with fenofibrate in the STITCH database with high confidence (0.7). Next, we investigated the identified proteins on curated targets in two databases, including the DisGeNET and DISEASES databases, to determine their association with NAFLD. We finally constructed a Venn diagram for these two collections (curated genes-NAFLD and fenofibrate-STITCH) to uncover possible primary targets of fenofibrate. Then, Gene Ontology (GO) and KEGG were analyzed to detect the significantly involved targets in molecular function, biological process, cellular component, and biological pathways. A P value < 0.01 was considered the cut-off criterion. We also estimated the specificity of targets with NAFLD by investigating them in disease-gene associations (STRING) and EnrichR (DisGeNET). Finally, we verified our findings in the scientific literature.

Results

We constructed two collections, one with 80 protein-drug interactions and the other with 95 genes associated with NAFLD. Using the Venn diagram, we identified 11 significant targets including LEP, SIRT1, ADIPOQ, PPARA, SREBF1, LDLR, GSTP1, VLDLR, SCARB1, MMP1, and APOC3 and then evaluated their biological pathways. Based on Gene Ontology, most of the targets are involved in lipid metabolism, and KEGG enrichment pathways showed the PPAR signaling pathway, AMPK signaling pathway, and NAFLD as the most significant pathways. The interrogation of those targets on authentic disease databases showed they were more specific to both steatosis and steatohepatitis liver injury than to any other diseases in these databases. Finally, we identified three significant genes, APOC3, PPARA, and SREBF1, that showed robust drug interaction with fenofibrate.

Conclusion

Fenofibrate may exert its effect directly or indirectly, via modulation of several key targets and pathways, in the treatment of NAFLD.

Investigation of candidate genes and mechanisms underlying obesity associated type 2 diabetes mellitus using bioinformatics analysis and screening of small drug molecules

BACKGROUND

Obesity associated type 2 diabetes mellitus is a metabolic disorder ; however, the etiology of obesity associated type 2 diabetes mellitus remains largely unknown. There is an urgent need to further broaden the understanding of the molecular mechanism associated in obesity associated type 2 diabetes mellitus.

METHODS

To screen the differentially expressed genes (DEGs) that might play essential roles in obesity associated type 2 diabetes mellitus, the publicly available expression profiling by high throughput sequencing data (GSE143319) was downloaded and screened for DEGs. Then, Gene Ontology (GO) and REACTOME pathway enrichment analysis were performed. The protein - protein interaction network, miRNA - target genes regulatory network and TF-target gene regulatory network were constructed and analyzed for identification of hub and target genes. The hub genes were validated by receiver operating characteristic (ROC) curve analysis and RT- PCR analysis. Finally, a molecular docking study was performed on over expressed proteins to predict the target small drug molecules.

RESULTS

A total of 820 DEGs were identified between healthy obese and metabolically unhealthy obese, among 409 up regulated and 411 down regulated genes. The GO enrichment analysis results showed that these DEGs were significantly enriched in ion transmembrane transport, intrinsic component of plasma membrane, transferase activity, transferring phosphorus-containing groups, cell adhesion, integral component of plasma membrane and signaling receptor binding, whereas, the REACTOME pathway enrichment analysis results showed that these DEGs were significantly enriched in integration of energy metabolism and extracellular matrix organization. The hub genes CEBPD, TP73, ESR2, TAB1, MAP 3K5, FN1, UBD, RUNX1, PIK3R2 and TNF, which might play an essential role in obesity associated type 2 diabetes mellitus was further screened.

CONCLUSIONS

The present study could deepen the understanding of the molecular mechanism of obesity associated type 2 diabetes mellitus, which could be useful in developing therapeutic targets for obesity associated type 2 diabetes mellitus.

Upregulated lncRNA HCG18 in Patients with Non-Alcoholic Fatty Liver Disease and Its Regulatory Effect on Insulin Resistance

PURPOSE

Non-alcoholic fatty liver disease (NAFLD) is a disease associated with genetic-environmental-metabolic stress, which severely damages the liver function of patients. This study aimed to explore the significance and probable functions of HCG18 in NAFLD.

PATIENTS AND METHODS

The expression of HCG18 and miR-197-3p was tested by qRT-PCR. The clinical signification of HCG18 was provided by the ROC curve and Pearson correlation. The corresponding mechanism was punctuated by the luciferase reporter assay and HFD-managed mice.

RESULTS

HCG18 expression was higher in the patients with NAFLD than in controls and in individuals with HOMA-IR score ≥2.5 than those with HOMA-IR score <2.5. HCG18 expression in NAFLD patients was related to BMI, HOMA-IR, ALT, FBG, TC, and TG. HCG18 showed satisfactory predictive accuracy in differentiating NAFLD patients and patients with HOMA-IR ≥2.5. Besides, HCG18 had protective impacts on blood glucose and fat deposition but not on body weight. MiR-197-3p is a direct gene of HCG18, and a reverse correlation was found between miR-197-3p and HCG18. Furthermore, miR-197-3p regulated the influence of HCG18 on insulin resistance and lipid accumulation.

CONCLUSION

Increased levels of HCG18 might be an alternate indicator for NAFLD patients. The HCG18-miR-197-3p axis exerted effects on the progression of fat sedimentation and glucose disorder in NAFLD.