Yunpi Heluo decoction attenuates insulin resistance by regulating liver miR-29a-3p in Zucker diabetic fatty rats

MicroRNAs in metabolic dysfunction-associated diseases: Pathogenesis and therapeutic opportunities

Metabolic dysfunction-associated diseases often refer to various diseases caused by metabolic problems such as glucose and lipid metabolism disorders. With the improvement of living standards, the increasing prevalence of metabolic diseases has become a severe public health problem, including metabolic dysfunction-associated steatotic liver disease (MASLD), alcohol-related liver disease (ALD), diabetes and obesity. These diseases are both independent and interdependent, with complex and diverse molecular mechanisms. Therefore, it is urgent to explore the molecular mechanisms and find effective therapeutic targets of these diseases. MicroRNAs (miRNAs) have emerged as key regulators of metabolic homoeostasis due to their multitargets and network regulatory properties within the past few decades. In this review, we discussed the latest progress in the roles of miRNA-mediated regulatory networks in the development and progression of MASLD, ALD, diabetes and obesity.

Exosomes: New Insights into the Pathogenesis of Metabolic Syndrome

Exosomes are a subtype of extracellular vesicles (EVs) with a diameter of 30~150 nm (averaging ~100 nm) that are primarily produced through the endosomal pathway, and carry various components such as lipids, proteins, RNA, and other small molecular substances. Exosomes can mediate intercellular communication through the bioactive substances they carry, thus participating in different physiological activities. Metabolic syndrome (MS) is a disease caused by disturbances in the body's metabolism, mainly including insulin resistance (IR), diabetes, obesity, non-alcoholic fatty liver disease (NAFLD), hyperlipidemia, and atherosclerosis (AS). Recent studies have shown that exosomes are closely related to the occurrence and development of MS. Exosomes can act as messengers to mediate signaling transductions between metabolic cells in the organism and play a bidirectional regulatory role in the MS process. This paper mainly reviews the components, biogenesis, biological functions and potential applications of exosomes, and exosomes involved in the pathogenesis of MS as well as their clinical significance in MS diagnosis.

Yunpi Heluo decoction reduces ectopic deposition of lipids by regulating the SIRT1-FoxO1 autophagy pathway in diabetic rats

CONTEXT

Yunpi Heluo (YPHL) decoction is a Chinese herbal formula with particular advantages for treating type 2 diabetes. Yet, its exact mechanism of action is not fully understood.

OBJECTIVE

To examine the therapeutic effect of YPHL on ectopic lipid deposition (EDL) in Zucker diabetic fatty (ZDF) rats and the underlying mechanism.

MATERIALS AND METHODS

The ZDF Rats were randomized into five groups, including model, YPHL (200 mg/kg/d for 10 weeks), SIRT1-overexpression (injected with HBAAV2/9-r-SIRT1-3'-flag-GFP), NC (injected with HBAAV2/9-CMV-GFP as blank control) and control group. Pancreatic β-cells obtained from high-lipid-high-glucose fed rats were treated with YPHL (10 mg/mL) for 48 h. Lipid deposition and autophagosomes were analyzed by transmission electron microscopy. Intracellular H₂O₂ and ROS concentrations were measured by flow cytometry. SIRT1, FOXO1, LC3 and P62 mRNA and protein levels were analyzed using qRT-PCR and Western blots.

RESULTS

Compared with the model group, blood glucose levels in YPHL and si-SIRT1 groups were reduced by 19.3% and 27.9%, respectively. In high-lipid-high-glucose cells treated with YPHL, lipid droplets were reduced and decrease in apoptosis rate (38.6%), H₂O₂ (31.2%) and ROS (44.5%) levels were observed. After YPHL intervention or SIRT1 overexpression, LC3 and p62 expression increased. Protein expression of SIRT1 and LC3 in model, si-SIRT1, si-NC and si-SIRT1 + YPHL groups was lower than those in control group, while FoxO1 expression was increased. All of these protein level alterations were reversed in the si-NC + YPHL group.

DISCUSSION AND CONCLUSIONS

YPHL reduced EDL by regulating the SIRT1-FoxO1 autophagy pathway in diabetic rats, which could lead to future perspectives for the treatment of diabetes.

Upregulation of miR-34a-5p, miR-20a-3p and miR-29a-3p by Onconase in A375 Melanoma Cells Correlates with the Downregulation of Specific Onco-Proteins

Onconase (ONC) is an amphibian secretory ribonuclease displaying cytostatic and cytotoxic activities against many mammalian tumors, including melanoma. ONC principally damages tRNA species, but also other non-coding RNAs, although its precise targets are not known. We investigated the ONC ability to modulate the expression of 16 onco-suppressor microRNAs (miRNAs) in the A375 BRAF-mutated melanoma cell line. RT-PCR and immunoblots were used to measure the expression levels of miRNAs and their regulated proteins, respectively. In silico study was carried out to verify the relations between miRNAs and their mRNA targets. A375 cell transfection with miR-20a-3p and miR-34a-5p mimics or inhibitors was performed. The onco-suppressors miR-20a-3p, miR-29a-3p and miR-34a-5p were highly expressed in 48-h ONC-treated A375 cells. The cytostatic effect of ONC in A375 cells was mechanistically explained by the sharp inhibition of cyclins D1 and A2 expression level, as well as by downregulation of retinoblastoma protein and cyclin-dependent-kinase-2 activities. Remarkably, the expression of kinases ERK1/2 and Akt, as well as of the hypoxia inducible factor-1α, was inhibited by ONC. All these proteins control pro-survival pathways. Finally, many crucial proteins involved in migration, invasion and metastatic potential were downregulated by ONC. Results obtained from transfection of miR-20a-3p and miR-34a-5p inhibitors in the presence of ONC show that these miRNAs may participate in the antitumor effects of ONC in the A375 cell line. In conclusion, we identified many intracellular downregulated proteins involved in melanoma cell proliferation, metabolism and progression. All mRNAs coding these proteins may be targets of miR-20a-3p, miR-29a-3p and/or miR-34a-5p, which are in turn upregulated by ONC. Data suggest that several known ONC anti-proliferative and anti-metastatic activities in A375 melanoma cells might depend on the upregulation of onco-suppressor miRNAs. Notably, miRNAs stability depends on the upstream regulation by long-non-coding-RNAs or circular-RNAs that can, in turn, be damaged by ONC ribonucleolytic activity.

Yunpi Heluo decoction attenuates insulin resistance by regulating SIRT1-FoxO1 autophagy pathway in skeletal muscle of Zucker diabetic fatty rats

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetes is a serious chronic metabolic disorder, and type 2 diabetes mellitus (T2DM) accounts for more than 90% of all diabetes cases. Insulin resistance (IR) is an early symptom, typical feature and main pathogenesis of T2DM due to the combined effects of genetic and environmental factors. Current evidence shows that IR is mainly caused by nutrient overload, systemic fatty acid excess, fatty tissue inflammation, endoplasmic reticulum stress, oxidative stress and abnormal autophagy. Autophagy plays an important role in the development of IR and decreased autophagy activity can cause IR through various ways.

AIM OF THE STUDY

Yunpiheluo (YPHL) decoction is a Chinese herbal formula with unique advantages for the treatment of T2DM. The aim of the present study was to investigate the regulatory mechanism of YPHL on the autophagy pathway in the skeletal muscle of IR Zucker diabetic fatty (ZDF) rats.

METHODS

T2DM ZDF rats were treated with YPHL or transfected with SIRT1 adeno-associated virus. Serum total cholesterol (TC), triglyceride (TG), high-density lipoprotein (HDL), low-density lipoprotein (LDL), insulin resistance index (IRI) and skeletal muscle TG levels were detected in a T2DM ZDF rat model. The skeletal muscle morphology was observed by histological analysis and Oil Red O Staining. Autophagosomes were observed by transmission electron microscopy (TEM). The skeletal muscle morphology and fat deposition were observed by histological examination and Oil Red O Staining. A rat skeletal muscle IR cell model was established and transfected with SIRT1 overexpression plasmids. Cell apoptosis was observed by DAPI staining. SIRT1 levels in skeletal muscle tissues and cells were detected by qRT-PCR. The protein expressions of SIRT1, FOXo1, LC3B and P62 were detected by Western blotting.

RESULTS

Large numbers of lipid droplets and swollen mitochondria were observed in the skeletal muscle in both model group and negative control (NC) group receiving blank plasmid. Autophagosomes were seen in the skeletal muscle of YPHL and SIRT1 groups, with no significant structural abnormality. In addition, the protein expression of LC3B was decreased and the protein expression of p62 was increased significantly in the model group as compared with the NC group. After intervention with YPHL and SIRT1 overexpression, the protein expression of LC3B was significantly increased and p62 was significantly decreased. However, there was no significant difference in cell apoptosis between the two groups.

CONCLUSION

The SIRT1-FoxO1 autophagy pathway may play a significant role in the pathogenesis of IR. YPHL could increase the autophagy level by regulating the SIRT1-FoxO1 signaling pathway in the skeletal muscle and improving the lipid metabolism, thereby attenuating IR.