Investigating microRNAs in diabetic cardiomyopathy as tools for early detection and therapeutics

Mechanistic insight into the role of cardiac-enriched microRNAs in diabetic heart injury

Cardiovascular complications, particularly diabetic cardiomyopathy (DCM), are the primary causes of morbidity and mortality among individuals with diabetes. Hyperglycemia associated with diabetes leads to cardiomyocyte hypertrophy, apoptosis, and myocardial fibrosis, culminating in heart failure (HF). Patients with diabetes face a 2-4 times greater risk of developing HF compared with those without diabetes. Consequently, there is a growing interest in exploring the molecular mechanisms that contribute to the development of DCM. MicroRNAs (miRNAs) are short, single-stranded, noncoding RNA molecules that participate in the maintenance of physiological homeostasis through the regulation of essential processes such as metabolism, cell proliferation, and apoptosis. At the posttranscriptional level, miRNAs modulate gene expression by binding directly to genes' mRNAs. Multiple cardiac-enriched miRNAs were reported to be dysregulated under diabetic conditions. Different studies revealed the role of specific miRNAs in the pathogenesis of diabetes and related cardiovascular complications, including cardiomyocyte hypertrophy and fibrosis, mitochondrial dysfunction, metabolic impairment, inflammatory response, or cardiomyocyte death. Circulating miRNAs have been shown to represent the potential biomarkers for early detection of diabetic heart injury. A deeper understanding of miRNAs and their role in diabetes-related pathophysiological processes could lead to new therapeutic strategies for addressing cardiac complications associated with diabetes.

Advances of research in diabetic cardiomyopathy: diagnosis and the emerging application of sequencing

Diabetic cardiomyopathy (DCM) is one of the most prevalent and severe complications associated with diabetes mellitus (DM). The onset of DCM is insidious, with the symptoms being obvious only in the late stage. Consequently, the early diagnosis of DCM is a formidable challenge which significantly influences the treatment and prognosis of DCM. Thus, it becomes imperative to uncover innovative approaches to facilitate the prompt identification and diagnosis of DCM. On the traditional clinical side, we tend to use serum biomarkers as well as imaging as the most common means of diagnosing diseases because of their convenience as well as affordability. As we delve deeper into the mechanisms of DCM, a wide variety of biomarkers are becoming competitive diagnostic indicators. Meanwhile, the application of multiple imaging techniques has also made efforts to promote the diagnosis of DCM. Besides, the spurt in sequencing technology has made it possible to give hints about disease diagnosis from the genome as well as the transcriptome, making diagnosis less difficult, more sensitive, and more predictive. Overall, sequencing technology is expected to be the superior choice of plasma biomarkers for detecting lesions at an earlier stage than imaging, and its judicious utilization combined with imaging technologies will lead to a more sensitive diagnosis of DCM in the future. Therefore, this review meticulously consolidates the progress and utilization of various biomarkers, imaging methods, and sequencing technologies in the realm of DCM diagnosis, with the aim of furnishing novel theoretical foundation and guide future research endeavors towards enhancing the diagnostic and therapeutic landscape of DCM.

MiR-503-5p alleviates peripheral neuropathy-induced neuropathic pain in T2DM mice by regulating SEPT9 to inhibit astrocyte activation

Diabetic peripheral neuropathy (DPN) is a common complication of type 2 diabetes mellitus (T2DM) that causes peripheral and autonomic nervous system dysfunction. Dysregulation of miRNAs plays a crucial role in DPN development. However, the role of miR-503-5p in DPN remains unknown. Herein, T2DM mice (db/db) were used as a DPN model in vivo, and astrocytes isolated from db/db mice were induced with high glucose levels as a DPN model in vitro. MiR-503-5p expression was analyzed using qRT-PCR. GFAP, MCP-1, and SEPT9 protein levels were analyzed using western blotting and immunofluorescence. Luciferase assays were performed to investigate the interaction between miR-503-5p and SEPT9. We found that miR-503-5p expression decreased in the spinal cord of DPN model mice and astrocytes treated with high glucose (HG). The db/db mice displayed higher body weight and blood glucose, lower mechanical withdrawal threshold and thermal withdrawal latency, and higher GFAP and MCP-1 protein levels than db/m mice. However, tail vein injection of agomiR-503-5p remarkably reversed these parameters, whereas antigomiR-503-5p enhanced them. HG markedly facilitated GFAP and MCP-1 protein expression in astrocytes, whereas miR-503-5p mimic or inhibitor transfection markedly blocked or elevated GFAP and MCP-1 protein expression, respectively, in astrocytes with HG. SEPT9 was a target of miR-503-5p. In addition, SEPT9 protein levels were found to be elevated in db/db mice and astrocytes treated with HG. Treatment with agomiR-503-5p and miR-503-5p mimic was able to reduce SEPT9 protein levels, whereas treatment with antigomiR-503-5p and miR-503-5p inhibitor led to inhibition of the protein. Furthermore, SEPT9 overexpression suppressed the depressing effect of miR-503-5p overexpression in astrocytes subjected to HG doses. In conclusion, miR-503-5p was found to alleviate peripheral neuropathy-induced neuropathic pain in T2DM mice by regulating SEPT9 expression.

MALAT1/miR-185-5p mediated high glucose-induced oxidative stress, mitochondrial injury and cardiomyocyte apoptosis via the RhoA/ROCK pathway

To explore the underlying mechanism of lncRNA MALAT1 in the pathogenesis of diabetic cardiomyopathy (DCM). DCM models were confirmed in db/db mice. MiRNAs in myocardium were detected by miRNA sequencing. The interactions of miR-185-5p with MALAT1 and RhoA were validated by dual-luciferase reporter assays. Primary neonatal cardiomyocytes were cultured with 5.5 or 30 mmol/L D-glucose (HG) in the presence or absence of MALAT1-shRNA and fasudil, a ROCK inhibitor. MALAT1 and miR-185-5p expression were determined by real-time quantitative PCR. The apoptotic cardiomyocytes were evaluated using flow cytometry and TUNEL staining. SOD activity and MDA contents were measured. The ROCK activity, phosphorylation of Drp1S616 , mitofusin 2 and apoptosis-related proteins were analysed by Western blotting. Mitochondrial membrane potential was examined by JC-1. MALAT1 was significantly up-regulated while miR-185-5p was down-regulated in myocardium of db/db mice and HG-induced cardiomyocytes. MALAT1 regulated RhoA/ROCK pathway via sponging miR-185-5p in cardiomyocytes in HG. Knockdown of MALAT1 and fasudil all inhibited HG-induced oxidative stress, and alleviated imbalance of mitochondrial dynamics and mitochondrial dysfunction, accompanied by reduced cardiomyocyte apoptosis. MALAT1 activated the RhoA/ROCK pathway via sponging miR-185-5p and mediated HG-induced oxidative stress, mitochondrial damage and apoptosis of cardiomyocytes in mice.

Mitochondrial transplantation: opportunities and challenges in the treatment of obesity, diabetes, and nonalcoholic fatty liver disease

Metabolic diseases, including obesity, diabetes, and nonalcoholic fatty liver disease (NAFLD), are rising in both incidence and prevalence and remain a major global health and socioeconomic burden in the twenty-first century. Despite an increasing understanding of these diseases, the lack of effective treatments remains an ongoing challenge. Mitochondria are key players in intracellular energy production, calcium homeostasis, signaling, and apoptosis. Emerging evidence shows that mitochondrial dysfunction participates in the pathogeneses of metabolic diseases. Exogenous supplementation with healthy mitochondria is emerging as a promising therapeutic approach to treating these diseases. This article reviews recent advances in the use of mitochondrial transplantation therapy (MRT) in such treatment.