MicroRNA-145 regulates disabled-2 and Wnt3a expression in cardiomyocytes under hyperglycaemia

Start small, think big: MicroRNAs in diabetes mellitus and relevant cardiorenal-liver metabolic health spectrum

Diabetes mellitus (DM), co-existing with metabolic disorder of cardio-renal-liver, is one of the most difficult problems in medicine that attracts global concern with high mortality. MicroRNAs (miRNAs) are a class of small non-coding RNA molecules that negatively regulates gene expression and exerts active against a large proportion of the transcriptome, due to their high evolutionary conservation. Emerging evidence prove that miRNAs are involved in the pathogenesis of DM and associated metabolic disorders, manifested by their variable alteration in the blood, urine, tissues, or organs, principally contributing to modulate the interconnections between DM and cardio-renal-liver metabolism. Mechanistically, miRNAs regulate various biological processes, such as metabolism of insulin, lipid, glucose, inflammatory response, fibrosis, oxidative stress, apoptosis, and angiogenesis, etc. This review emphasizes the function of miRNAs and highlights the physiopathological regulation of miRNA in DM and related complications, especially the dysfunction of cardiovascular system, kidneys, and liver, with the aim of providing promising biomarkers for assisting early diagnosis of DM with cardio-renal-liver- specific metabolic disorders, as well as for the development of miRNA-targeting agents.

The Role of Wnt3a/β-Catenin/TCF7L2 Pathway in Diabetes and Cardiorenal Complications

BACKGROUND

Diabetes mellitus is a prevalent chronic disease that is becoming increasingly common worldwide and can lead to a number of dangerous complications. The Wnt signaling pathway is important for the onset and progression of diabetes. Wnt3a is a typical Wnt ligand that can increase the stability of β-catenin, control TCF7L2 expression, promote β-cell proliferation, and reduce apoptosis.

SUMMARY

The involvement of the Wnt3a/β-catenin/TCF7L2 signaling pathway in the development of diabetes and associated problems related to the kidneys is reviewed in this article.

KEY MESSAGE

We believe that a thorough comprehension of the molecular connections between diabetes and signaling pathways will eventually lead to improved diabetes management.

Genetic polymorphism of the Dab2 gene and its association with Type 2 Diabetes Mellitus in the Chinese Uyghur population

Objective

The human Disabled-2 (Dab2) protein is an endocytic adaptor protein, which plays an essential role in endocytosis of transmembrane cargo, including low-density lipoprotein cholesterol (LDL-C). As a candidate gene for dyslipidemia, Dab2 is also involved in the development of type 2 diabetes mellitus(T2DM). The aim of this study was to investigate the effects of genetic variants of the Dab2 gene on the related risk of T2DM in the Uygur and Han populations of Xinjiang, China.

Methods

A total of 2,157 age- and sex-matched individuals (528 T2DM patients and 1,629 controls) were included in this case-control study. Four high frequency SNPs (rs1050903, rs2255280, rs2855512 and rs11959928) of the Dab2 gene were genotyped using an improved multiplex ligation detection reaction (iMLDR) genotyping assay, and the forecast value of the SNP for T2DM was assessed by statistical analysis of clinical data profiles and gene frequencies.

Results

We found that in the Uygur population studied, for both rs2255280 and rs2855512, there were significant differences in the distribution of genotypes (AA/CA/CC), and the recessive model (CC vs. CA + AA) between T2DM patients and the controls (P < 0.05). After adjusting for confounders, the recessive model (CC vs. CA + AA) of both rs2255280 and rs2855512 remained significantly associated with T2DM in this population (rs2255280: OR = 5.303, 95% CI [1.236 to -22.755], P = 0.025; rs2855512: OR = 4.892, 95% CI [1.136 to -21.013], P = 0.033). The genotypes (AA/CA/CC) and recessive models (CC vs. CA + AA) of rs2855512 and rs2255280 were also associated with the plasma glucose and HbA1c levels (all P < 0.05) in this population. There were no significant differences in genotypes, all genetic models, or allele frequencies between the T2DM and control group in the Han population group (all P > 0.05).

Conclusions

The present study suggests that the variation of the Dab2 gene loci rs2255280 and rs2855512 is related to the incidence of T2DM in the Uygur population, but not in the Han population. In this study, these variations in Dab2 were an independent predictor for T2DM in the Uygur population of Xinjiang, China.

Disabled-2 (DAB2): A Key Regulator of Anti- and Pro-Tumorigenic Pathways

Disabled-2 (DAB2), a key adaptor protein in clathrin mediated endocytosis, is implicated in the regulation of key signalling pathways involved in homeostasis, cell positioning and epithelial to mesenchymal transition (EMT). It was initially identified as a tumour suppressor implicated in the initiation of ovarian cancer, but was subsequently linked to many other cancer types. DAB2 contains key functional domains which allow it to negatively regulate key signalling pathways including the mitogen activated protein kinase (MAPK), wingless/integrated (Wnt) and transforming growth factor beta (TGFβ) pathways. Loss of DAB2 is primarily associated with activation of these pathways and tumour progression, however this review also explores studies which demonstrate the complex nature of DAB2 function with pro-tumorigenic effects. A recent strong interest in microRNAs (miRNA) in cancer has identified DAB2 as a common target. This has reignited an interest in DAB2 research in cancer. Transcriptomics of tumour associated macrophages (TAMs) has also identified a pro-metastatic role of DAB2 in the tumour microenvironment. This review will cover the broad depth literature on the tumour suppressor role of DAB2, highlighting its complex relationships with different pathways. Furthermore, it will explore recent findings which suggest DAB2 has a more complex role in cancer than initially thought.

In Vivo Treatment with a Standardized Green Tea Extract Restores Cardiomyocyte Contractility in Diabetic Rats by Improving Mitochondrial Function through SIRT1 Activation

Background. Green tea catechins are known to promote mitochondrial function, and to modulate gene expression and signalling pathways that are altered in the diabetic heart. We thus evaluated the effectiveness of the in vivo administration of a standardized green tea extract (GTE) in restoring cardiac performance, in a rat model of early streptozotocin-induced diabetes, with a focus on the underlying mechanisms. Methods. Twenty-five male adult Wistar rats were studied: the control (n = 9), untreated diabetic animals (n = 7) and diabetic rats subjected to daily GTE administration for 28 days (n = 9). Isolated ventricular cardiomyocytes were used for ex vivo measurements of cell mechanics and calcium transients, and molecular assays, including the analysis of functional protein and specific miRNA expression. Results. GTE treatment induced an almost complete recovery of cardiomyocyte contractility that was markedly impaired in the diabetic cells, by preserving mitochondrial function and energy availability, and modulating the expression of the sarcoplasmic reticulum calcium ATPase and phospholamban. Increased Sirtuin 1 (SIRT1) expression and activity substantially contributed to the observed cardioprotective effects. Conclusions. The data supported the hypothesis that green tea dietary polyphenols, by targeting SIRT1, can constitute an adjuvant strategy for counteracting the initial damage of the diabetic heart, before the occurrence of diabetic cardiomyopathy.

The effect of eight weeks of moderate and high intensity aerobic training on the gene expression of Mir-145, Wnt3a and Dab2 in the heart tissue of type 2 diabetic rats

Purpose

Pathological hypertrophy of heart tissue has been attributed to changes in some microRNAs and their target genes in heart tissue. This study intended to study the effects of eight weeks of moderate and high intensity aerobic training (MIT&HIT) on the mRNA of Mir-145, Wnt3a, and Dab2 in heart tissue of type 2 diabetic rats.

Methods

To implement this experimental research, 60 male Wistar rats were randomly divided into 6 groups, including Healthy-control (HC), Diabetic-control (DC), Moderate intensity training (MIT), Diabetes-MIT (DMIT), high intensity training (HIT) and Diabetes-HIT (DHIT). The aerobic training was conducted with moderate (50-60% VO2max) and high (85-90% VO2max) intensity, 5 days a week, for 8 weeks. The Mir-145, Wnt3a and Dab2 gene expression in the heart tissue samples was measured by Real Time PCR. Data were analyzed by one-way ANOVA and Tukey post hoc test at the P < 0.05.

Results

Moderate and high intensity aerobic training was associated with non-significant increase in Mir-145 mRNA of Heart tissue in type 2 diabetic rats than the diabetic control group(P < 0.05). Moderate and high intensity aerobic training was associated with significant increase in Wnt3a mRNA (P = 0.001) and significant decrease in Dab-2 mRNA (P = 0.001) of Heart tissue in type 2 diabetic rats than the diabetic control group. The Dab-2 mRNA was significantly lower of heart tissue in the diabetes- high intensity training group than the diabetes- moderate intensity training group (P = 0.001).

Conclusion

It seems that moderate and high intensity aerobic exercise can help regulate the genes of the physiological hypertrophy pathway of the heart tissue in diabetes.

The complex role of Wnt ligands in type 2 diabetes mellitus and related complications

Type 2 diabetes mellitus (T2DM) is one of the major chronic diseases, whose prevalence is increasing dramatically worldwide and can lead to a range of serious complications. Wnt ligands (Wnts) and their activating Wnt signalling pathways are closely involved in the regulation of various processes that are important for the occurrence and progression of T2DM and related complications. However, our understanding of their roles in these diseases is quite rudimentary due to the numerous family members of Wnts and conflicting effects via activating the canonical and/or non-canonical Wnt signalling pathways. In this review, we summarize the current findings on the expression pattern and exact role of each human Wnt in T2DM and related complications, including Wnt1, Wnt2, Wnt2b, Wnt3, Wnt3a, Wnt4, Wnt5a, Wnt5b, Wnt6, Wnt7a, Wnt7b, Wnt8a, Wnt8b, Wnt9a, Wnt9b, Wnt10a, Wnt10b, Wnt11 and Wnt16. Moreover, the role of main antagonists (sFRPs and WIF-1) and coreceptor (LRP6) of Wnts in T2DM and related complications and main challenges in designing Wnt-based therapeutic approaches for these diseases are discussed. We hope a deep understanding of the mechanistic links between Wnt signalling pathways and diabetic-related diseases will ultimately result in a better management of these diseases.

Long non-coding RNA MEG3 serves as a ceRNA for microRNA-145 to induce apoptosis of AC16 cardiomyocytes under high glucose condition

Diabetic cardiomyopathy (DCM) is one of the most serious complications of diabetes, but its pathogenesis remains largely unclear. In the present study, we aimed to explore the potential role of long non-coding RNA (lncRNA) maternally expressed gene 3 (MEG3) and to investigate the underlying mechanisms in human AC16 cardiomyocytes under high glucose (HG) condition. The results demonstrated that MEG3 was overexpressed in HG-treated AC16 cells, and MEG3 knockdown suppressed the HG-induced apoptosis in AC16 cells. Mechanistically, MEG3 directly binds to miR-145 in AC16 cells, thereby up-regulating the expression of PDCD4. Rescue experiments showed that the role of MEG3 in HG-treated AC16 cells was partly dependent on its suppression on miR-145. In summary, our findings suggested that the role of MEG3 in HG-treated human cardiomyocytes is to serve as a competing endogenous RNA (ceRNA), which negatively regulates miR-145. These findings may provide a valuable and promising therapeutic target for the treatment of DCM in the future.

Hyperglycemia inhibition of endothelial miR-140-3p mediates angiogenic dysfunction in diabetes mellitus

OBJECTIVE

MicroRNAs (miRNAs) have emerged as promising regulators of diabetes mellitus (DM)-induced angiogenic dysfunction in endothelial cells (ECs), but information vis-à-vis the functional roles of distinct miRNAs remain surprisingly scarce. The current study was designed to elucidate the expression and function of miR-140-3p in diabetic ECs.

METHODS

miR-140-3p expression was evaluated in DM mouse model and in human ECs using RT-qPCR, Northern blot and RNA fluorescent in situ hybridization. Effects of miR-140-3p manipulation on ECs function were evaluated using cell proliferation, migration and in vitro tube formation assay. Regulation of FOXK2 transcription by miR-140-3p was determined by luciferase reporter assay and site-directed mutagenesis.

RESULTS

miR-140-3p expression was significantly down-regulated in high glucose-challenged ECs. Under normal conditions, miR-140-3p knockdown impaired endothelial proliferation and migration, and endothelial tube formation. Mechanistically, miR-140-3p exhibited its proangiogenic effects through directly inhibiting the expression of the forkhead transcription factor FOXK2. From a therapeutic standpoint, shRNA-mediated stable inhibition of FOXK2 effectively corrected miR-140-3p deficiency-induced impairment of ECs proliferation and in vitro angiogenesis.

CONCLUSION

Endothelial miR-140-3p positive regulates ECs function by directly targeting FOXK2 signaling. Deregulation of miR-140-3p/FOXK2 cascade by hyperglycemia thus serves as an important contributor to angiogenic dysfunction in DM.

MicroRNA-377 Inhibits Atherosclerosis by Regulating Triglyceride Metabolism Through the DNA Methyltransferase 1 in Apolipoprotein E-Knockout Mice

BACKGROUND

Lipoprotein lipase (LPL) plays an important role in triglyceride metabolism. It is translocated across endothelial cells to reach the luminal surface of capillaries by glycosylphosphatidylinositol-anchored high-density lipoprotein binding protein 1 (GPIHBP1), where it hydrolyzes triglycerides in lipoproteins. MicroRNA 377 (miR-377) is highly associated with lipid levels. However, how miR-377 regulates triglyceride metabolism and whether it is involved in the development of atherosclerosis remain largely unexplored.

METHODS AND RESULTS

The clinical examination displayed that miR-377 expression was markedly lower in plasma from patients with hypertriglyceridemia compared with non-hypertriglyceridemic subjects. Bioinformatics analyses and a luciferase reporter assay showed that DNA methyltransferase 1 (DNMT1) was a target gene of miR-377. Moreover, miR-377 increased LPL binding to GPIHBP1 by directly targeting DNMT1 in human umbilical vein endothelial cells (HUVECs) and apolipoprotein E (ApoE)-knockout (KO) mice aorta endothelial cells (MAECs). In vivo, hematoxylin-eosin (H&E), Oil Red O and Masson's trichrome staining showed that ApoE-KO mice treated with miR-377 developed less atherosclerotic plaques, accompanied by reduced plasma triglyceride levels.

CONCLUSIONS

It is concluded that miR-377 upregulates GPIHBP1 expression, increases the LPL binding to GPIHBP1, and reduces plasma triglyceride levels, likely through targeting DNMT1, inhibiting atherosclerosis in ApoE-KO mice.