New advances of adiponectin in regulating obesity and related metabolic syndromes

Exercise-promoted adiponectin secretion activates autolysosomes to protect the liver of ApoE-/- mice from a high-fat diet

Fat is a "double-edged sword": while it is a necessary substance for the body, the long-term intake of excessive fat will cause obesity, with the liver subjected to lipotoxicity as it accumulates. It will then continue to deteriorate, eventually leading to liver failure, which is a negative impact of high-fat food intake. Research has shown that exercise can reverse the side effects of a chronic high-fat diet and help the body to mitigate the harmful effects of lipotoxicity. In our study, it was found that moderate-intensity cardio-training (MICT) and high-intensity interval exercise (HIIT) effectively protected the livers of high-fat diet (HFD) ApoE-/- mice against lipotoxicity. Previous results demonstrated that 12 weeks of HFD resulted in a significant elevation of CD36 in the livers of C57BL/6J mice, while knockdown of CD36 did not reduce the accumulation of fat in the liver. Therefore, we used ApoE-/- mice as experimental subjects. Although HFD caused the development of hyperlipidemia and atherosclerosis, it is interesting to note that, due to the knockdown of ApoE, the livers of ApoE-/- mice in the non-exercise group did not show significant lipid deposition; however, after 12 weeks of MICT and HIIT, the livers of ApoE-/- mice showed significant lipid deposition. After we analyzed the lipid metabolism in their livers, we found that this was caused by the promotion of transport of peripheral fat into the liver due to exercise. Moreover, 12 weeks of exercise effectively reduced atherosclerosis, and the livers of ApoE-/- mice in the exercise group were not damaged by lipotoxicity. The results showed that a 12-week exercise treatment activated AMPK in the livers of HFD ApoE-/- mice through the APN-AdipoR1 signaling pathway, improved hepatic lipid metabolism disorders, and promoted the nuclear translocation of TFEB to enhance autophagic-lysosomal lipid scavenging. After the peripheral lipid is input into the liver due to exercise, the energy generated through gluconeogenesis can be used to replenish the energy consumed by exercise and maintain the normal operation of various functions in the liver, based on which the high autophagic flux in the liver can be maintained and the lipid clearance rate can be enhanced to protect the liver from lipotoxicity.

Roles of Lysine Methylation in Glucose and Lipid Metabolism: Functions, Regulatory Mechanisms, and Therapeutic Implications

Glucose and lipid metabolism are essential energy sources for the body. Dysregulation in these metabolic pathways is a significant risk factor for numerous acute and chronic diseases, including type 2 diabetes (T2DM), Alzheimer's disease (AD), obesity, and cancer. Post-translational modifications (PTMs), which regulate protein structure, localization, function, and activity, play a crucial role in managing cellular glucose and lipid metabolism. Among these PTMs, lysine methylation stands out as a key dynamic modification vital for the epigenetic regulation of gene transcription. Emerging evidence indicates that lysine methylation significantly impacts glucose and lipid metabolism by modifying key enzymes and proteins. This review summarizes the current understanding of lysine methylation's role and regulatory mechanisms in glucose and lipid metabolism. We highlight the involvement of methyltransferases (KMTs) and demethylases (KDMs) in generating abnormal methylation signals affecting these metabolic pathways. Additionally, we discuss the chemical biology and pharmacology of KMT and KDM inhibitors and targeted protein degraders, emphasizing their clinical implications for diseases such as diabetes, obesity, neurodegenerative disorders, and cancers. This review suggests that targeting lysine methylation in glucose and lipid metabolism could be an ideal therapeutic strategy for treating these diseases.

Changes in the Expression of Inflammatory Genes Induced by Chronic Exercise in the Adipose Tissue: Differences by Sex

The impact of obesity on adipose tissue function is well acknowledged, but the role of physical exercise in regulating inflammatory markers and gene expression in obese individuals remains uncertain. This study aims to investigate the effects of chronic exercise on inflammatory gene expression in adipose tissue and to explore sex differences in response to exercise. The study involved 29 obese participants (13 men, 16 women) aged 38 to 54 years with a mean BMI of 36.05 ± 4.99 kg/m2. Participants underwent an 8-week concurrent training program comprising three weekly sessions of ~60 min each. The sessions included joint mobility exercises, cardiovascular activation, and cardiorespiratory resistance exercises at medium to low intensity. A fine-needle aspiration biopsy of abdominal subcutaneous adipose tissue was performed for gene expression analysis using quantitative polymerase chain reaction (qPCR). The study demonstrated that chronic exercise modulates the expression of pro-inflammatory genes in subcutaneous adipose tissue, particularly ADIPOR2 (p = 0.028), leptin (p = 0.041), and IFNg (p = 0.040) (downregulated). Interestingly, regardless of sex, the exercise programs had an independent effect on pro-inflammatory genes. Overall, this study provides insight into the role of chronic exercise in modulating adipose tissue gene expression in obese individuals. Further research involving both sexes is recommended to tailor exercise interventions for better outcomes.

Reevaluating Adiponectin's impact on obesity hypertension: a Chinese case-control study

BACKGROUND

Obesity and hypertension are major risk factors for cardiovascular diseases that affect millions of people worldwide. Both conditions are associated with chronic low-grade inflammation, which is mediated by adipokines such as adiponectin. Adiponectin is the most abundant adipokine that has a beneficial impact on metabolic and vascular biology, while high serum concentrations are associated with some syndromes. This "adiponectin paradox" still needs to be clarified in obesity-associated hypertension. The aim of this study was to investigate how adiponectin affects blood pressure, inflammation, and metabolic function in obesity hypertension using a Chinese adult case-control study.

METHODS

A case-control study that had finished recruiting 153 subjects divided as four characteristic groups. Adiponectin serum levels were tested by ELISA in these subjects among these four characteristic Chinese adult physical examination groups. Waist circumference (WC), body mass index (BMI), systolic blood pressure (SB), diastolic blood pressure (DB), and other clinical laboratory data were collected. Analyzation of correlations between the research index and differences between groups was done by SPSS.

RESULTS

Serum adiponectin levels in the| normal healthy group (NH group) were significantly higher than those in the newly diagnosed untreated just-obesity group (JO group), and negatively correlated with the visceral adiposity index. With multiple linear egression analysis, it was found that, for serum adiponectin, gender, serum albumin (ALB), alanine aminotransferase (ALT) and high-density lipoprotein cholesterol (HDLC) were the significant independent correlates, and for SB, age and HDLC were the significant independent correlates, and for DB, alkaline phosphatase (ALP) was the significant independent correlate. The other variables did not reach significance in the model.

CONCLUSIONS

Our study reveals that adiponectin's role in obesity-hypertension is multifaceted and is influenced by the systemic metabolic homeostasis signaling axis. In obesity-related hypertension, compensatory effects, adiponectin resistance, and reduced adiponectin clearance from impaired kidneys and liver all contribute to the "adiponectin paradox".