Role of regulatory micro RNAs in type 2 diabetes mellitus-related inflammation

Plasma miR-193b-3p Is Elevated in Type 2 Diabetes and Could Impair Glucose Metabolism

OBJECTIVE

To explore differentially expressed miRNAs in type 2 diabetes and their potential cellular functions.

METHODS

We screened plasma miRNAs by miRNA array analysis and validated them by TaqMan real-time PCR in 113 newly diagnosed, untreated type 2 diabetes cases and 113 healthy controls. Low-abundance plasma proteins encoded by miR-193b-3p target genes were explored in this study population. We further investigated the potential cellular functions of the differentially expressed miRNAs in HepG2 cells.

RESULTS

miR-193b-3p was differentially expressed in type 2 diabetes cases compared to healthy controls (fold change = 2.01, P = 0.006). Plasma levels of triosephosphate isomerase (TPI1, a protein involved in the glycolytic pathway) decreased in type 2 diabetes cases (fold change = 1.37, P = 0.002). The effect of miR-193b-3p on TPI1 was verified by transfection of miR-193b-3p into HepG2 cells. miR-193b-3p inhibited the expression of YWHAZ/14-3-3ζ in the PI3K-AKT pathway, subsequently altering the expression of FOXO1 and PCK1. After transfection, cells were incubated in glucose-free medium for another 4 h. Glucose levels in medium from cells with elevated miR-193b-3p levels were significantly higher than those in medium from negative control cells (P = 0.016). In addition, elevated miR-193b-3p reduced glucose uptake by inhibiting insulin receptor (IR) and GLUT2 expression.

CONCLUSION

Plasma miR-193b-3p levels increased in type 2 diabetes cases, and TPI1 levels decreased in both plasma and HepG2 cells with increased miR-193b-3p levels, while extracellular lactate levels did not significantly changed. Moreover, miR-193b-3p may affect glucose metabolism by directly targeting YWHAZ/14-3-3ζ and upregulating the transcription factor FOXO1 downstream of the PI3K-AKT pathway.

Periodontal Pathogens and Neuropsychiatric Health

Increasing evidence incriminates low-grade inflammation in cardiovascular, metabolic diseases, and neuropsychiatric clinical conditions, all important causes of morbidity and mortality. One of the upstream and modifiable precipitants and perpetrators of inflammation is chronic periodontitis, a polymicrobial infection with Porphyromonas gingivalis (P. gingivalis) playing a central role in the disease pathogenesis. We review the association between P. gingivalis and cardiovascular, metabolic, and neuropsychiatric illness, and the molecular mechanisms potentially implicated in immune upregulation as well as downregulation induced by the pathogen. In addition to inflammation, translocation of the pathogens to the coronary and peripheral arteries, including brain vasculature, and gut and liver vasculature has important pathophysiological consequences. Distant effects via translocation rely on virulence factors of P. gingivalis such as gingipains, on its synergistic interactions with other pathogens, and on its capability to manipulate the immune system via several mechanisms, including its capacity to induce production of immune-downregulating micro-RNAs. Possible targets for intervention and drug development to manage distal consequences of infection with P. gingivalis are also reviewed.

Identification of stress-related microRNA biomarkers in type 2 diabetes mellitus: A systematic review and meta-analysis

BACKGROUND

Many studies have investigated microRNAs (miRNAs) in the detection of type 2 diabetes mellitus (T2DM). Herein, the dysregulated direction of stress-related miRNAs used as biomarkers of T2DM are summarized and analyzed.

METHODS

PubMed, EMBASE, ISI Web of Science, and three Chinese databases were searched for case-control miRNA profiling studies about T2DM. A meta-analysis under a random effect was performed. Subgroup analysis was conducted based on different tissues and species. Sensitivity analysis was conducted to confirm the robustness among studies. The effect size was pooled using ln odds ratios (ORs), 95% confidence intervals (95% CIs), and P-values.

RESULTS

The present meta-analysis included 39 case-control studies with a total of 494 miRNAs. Only 33 miRNAs were reported in three or more studies and, of these, 18 were inconsistent in their direction of dysregulation. Two significantly dysregulated miRNAs (let-7 g and miR-155) were identified in the meta-analysis. Four miRNAs (miR-142-3p, miR-155, miR-21, and miR-34c-5p) were dysregulated in patients with T2DM, whereas five miRNAs (miR-146a, miR-199a-3p, miR-200b, miR-29b and miR-30e) were dysregulated in animal models of diabetes. In addition, two dysregulated miRNAs (miR-146a and miR-21) were highly cornea specific and heart specific. In sensitivity analysis, only miR-155 was still significantly dysregulated after removing studies with small sample sizes.

CONCLUSIONS

The present meta-analysis revealed that 16 stress-related miRNAs were significantly dysregulated in T2DM. MiR-148b, miR-223, miR-130a, miR-19a, miR-26b and miR-27b were selected as potential circulating biomarkers of T2DM. In addition, miR-146a and miR-21 were identified as potential tissue biomarkers of T2DM.

Differential Regulatory Roles of MicroRNAs in Porcine Intramuscular and Subcutaneous Adipocytes

The deposition of intramuscular (IM) and subcutaneous (SC) fat is an important trait influencing pork quality. Understanding the genetic differences between these two types of adipose tissues is consequently of great importance for pig breeding. Here, we established primary cultures of IM and SC adipocytes from Jiaxing black pigs. The microRNA (miRNA) expression profiles of the two types of adipocytes were obtained by RNA-seq. A total of 741 miRNAs were identified in IM and SC adipocytes, including 155 significant differentially expressed (SDE) miRNAs. According to gene ontology and Kyoto Encyclopedia of Genes analysis, the target genes of the SDE miRNAs were enriched in categories and pathways related to transcriptional regulation, fatty acid biosynthesis, as well as the MAPK and PI3K/Akt pathways. Notably, miR-206 expression was 36-fold higher in IM adipocytes than in SC adipocytes. The overexpression of miR-206 in IM and SC adipocytes decreased cell proliferation and triglyceride accumulation. Luciferase activity assays and quantitative polymerase chain reaction confirmed that miR-206 regulates adipocyte proliferation by targeting STARD7 and inhibits adipogenesis by repressing Krüppel-like factor 4 (KLF4) expression. Accordingly, the effect of miR-206 mimics was attenuated by the overexpression of KLF4 in adipocytes. Taken together, we identified the expression profiles of miRNAs in adipocytes, which revealed that miR-206 acts as a suppressor of adipogenesis.

Tanshinone IIA improves diabetes mellitus via the NF-κB-induced AMPK signal pathway

Diabetes mellitus (DM) is a systemic metabolic disease. Tanshinone IIA (Tan-IIA) presents potential benefits for DM. The purpose of this study was to investigate the efficacy of Tan-IIA in type 2 DM rats and explore its potential mechanism in renal cells. A type 2 DM rat model was established and administered with Tan-IIA or PBS. It was demonstrated that Tan-IIA treatment significantly reduced levels of total cholesterol, non-esterified fatty acids, total triglyceride and low-density lipoprotein cholesterol in experimental DM rats compared with the control group. The results indicated that Tan-IIA treatment significantly decreased levels of interleukin (IL)-8, tumor necrosis factor-α, C-reactive protein and IL-6. It was identified that Tan-IIA treatment significantly decreased nuclear factor-κB levels and significantly elevated 5' adenosine monophosphate-activated protein kinase levels. Western blot analysis indicated that Tan-IIA elevated immunocyte precipitation in renal cells. Furthermore, Tan-IIA treatment improved lipid metabolism, glucose metabolism, insulin resistance and body weight of type 2 DM rats. In conclusion, Tan-IIA administration may inhibit inflammatory cytokines and alleviate type 2 DM symptoms in experimental rats.

MicroRNA-216b actively modulates diabetic angiopathy through inverse regulation on FZD5

BACKGROUND

In this work, we examined the angiogenic function of microRNA-216b in an in vitro rat diabetic model of myocardial microvascular endothelial cells (MMECs).

METHODS

MMECs were extracted from Wistar rats (MMEC(WI)) or diabetic Goto-Kakizaki (GK) rats (MMEC(GK)) and cultured in vitro. QRT-PCR was applied to compare miR-216b between MMEC(WI) and MMEC(GK). MiR-216b was downregulated in MMEC(GK). Its effects on angiogenic development, including invasion and proliferation, were evaluated. In MMEC(GK), putative miR-216b downstream target gene, frizzled class receptor 5 (FZD5), was evaluated by dual-luciferase reporter, qRT-PCR and western blot assays, respectively. FZD5 was further downregulated in MMEC(GK) with stable miR-216b downregulation to evaluate its functional role in regulating diabetic angiogenesis.

RESULTS

MiR-216b was markedly overexpressed in MMEC(GK). MiR-216b downregulation significantly enhanced angiogenesis in MMEC(GK) by promoting invasion and proliferation. FZD5 was inversely upregulated in miR-216b-downregulated MMEC(GK). Subsequently, FZD5 downregulation suppressed angiogenic development, by inhibiting invasion and proliferation in miR-216b-downregulated MMEC(GK).

CONCLUSION

MicroRNA-216b was overexposed in diabetic MMECs and its downregulation may actively enhance angiogenesis in diabetic angiopathy through inverse regulation on FZD5.

Identification of Potential MicroRNA Biomarkers by Meta-analysis

Meta-analysis statistically assesses the results (e.g., effect sizes) across independent studies that are conducted in accordance with similar protocols and objectives. Current genomic meta-analysis studies do not perform extensive re-analysis on raw data because full data access would not be commonplace, although the best practice of open research for sharing well-formed data have been actively advocated. This chapter describes a simple and easy-to-follow method for conducting meta-analysis of multiple studies without using raw data. Examples for meta-analysis of microRNAs (miRNAs) are provided to illustrate the method. MiRNAs are potential biomarkers for early diagnosis and epigenetic monitoring of diseases. A number of miRNAs have been identified to be differentially expressed, i.e., overexpressed or underexpressed, under diseased states but only a small fraction would be highly effective biomarkers or therapeutic targets of diseases. The meta-analysis method as described in this chapter aims to identify the miRNAs that are consistently found dysregulated across independent studies as biomarkers.

A Systematic Study of Dysregulated MicroRNA in Type 2 Diabetes Mellitus

MicroRNAs (miRNAs) are small noncoding RNAs that modulate the cellular transcriptome at the post-transcriptional level. miRNA plays important roles in different disease manifestation, including type 2 diabetes mellitus (T2DM). Many studies have characterized the changes of miRNAs in T2DM, a complex systematic disease; however, few studies have integrated these findings and explored the functional effects of the dysregulated miRNAs identified. To investigate the involvement of miRNAs in T2DM, we obtained and analyzed all relevant studies published prior to 18 October 2016 from various literature databases. From 59 independent studies that met the inclusion criteria, we identified 158 dysregulated miRNAs in seven different major sample types. To understand the functional impact of these deregulated miRNAs, we performed targets prediction and pathway enrichment analysis. Results from our analysis suggested that the altered miRNAs are involved in the core processes associated with T2DM, such as carbohydrate and lipid metabolisms, insulin signaling pathway and the adipocytokine signaling pathway. This systematic survey of dysregulated miRNAs provides molecular insights on the effect of deregulated miRNAs in different tissues during the development of diabetes. Some of these miRNAs and their mRNA targets may have diagnostic and/or therapeutic utilities in T2DM.

MicroRNA Regulation of Epithelial to Mesenchymal Transition

Epithelial to mesenchymal transition (EMT) is a central regulatory program that is similar in many aspects to several steps of embryonic morphogenesis. In addition to its physiological role in tissue repair and wound healing, EMT contributes to chemo resistance, metastatic dissemination and fibrosis, amongst others. Classically, the morphological change from epithelial to mesenchymal phenotype is characterized by the appearance or loss of a group of proteins which have come to be recognized as markers of the EMT process. As with all proteins, these molecules are controlled at the transcriptional and translational level by transcription factors and microRNAs, respectively. A group of developmental transcription factors form the backbone of the EMT cascade and a large body of evidence shows that microRNAs are heavily involved in the successful coordination of mesenchymal transformation and vice versa, either by suppressing the expression of different groups of transcription factors, or otherwise acting as their functional mediators in orchestrating EMT. This article dissects the contribution of microRNAs to EMT and analyzes the molecular basis for their roles in this cellular process. Here, we emphasize their interaction with core transcription factors like the zinc finger enhancer (E)-box binding homeobox (ZEB), Snail and Twist families as well as some pluripotency transcription factors.

Patients With Neurogenic Lower Urinary Tract Dysfunction Following Spinal Cord Injury Are at Increased Risk of Developing Type 2 Diabetes Mellitus: A Population-Based Cohort Study

To investigate whether patients with neurogenic lower urinary tract dysfunction (NLUTD) following spinal cord injury (SCI) are at increased risk of developing type 2 diabetes mellitus (T2DM).The retrospective cohort study used a subset of the Taiwan National Health Insurance Research Database (NHIRD) comprising information on 2 million beneficiaries randomly sampled from the general population. A total of 3515 patients with newly diagnosed SCI were identified during the period of 2001 to 2008. Among them, 170 developed NLUTD following SCI. The control group was consisted of 656 patients without NLUTD over the study period randomly selected by matching NLUTD cases on the date of NLUTD incidence, age, sex, and duration since diagnosis of SCI. The study groups were then followed to the end of 2009. T2DM was the end-point.The incidence rate ratios of T2DM were higher in the NLUTD group than in the control group (4.94 vs. 2.61 per 10,000 person-years), representing an adjusted hazard ratio (AHR) of 1.70 (95% confidence interval [CI] 1.11-2.61). Age-specific AHR was significantly elevated only in patients aged > = 60 years (AHR = 2.52 (95% CI 1.35-4.70)).This study showed that the NLUTD following SCI may significantly increase the risk of developing T2DM.

Inhibition of microRNA-9-3p reduces lipid accumulation in HepG2 cells by targeting the expression of sirtuin type 1

Type 2 diabetes mellitus (T2DM) is a complex metabolic disorder caused by the interaction of environmental factors and multiple genes. The genetic background of T2DM is complex and remains to be fully elucidated. MicroRNAs (miRNAs) are negative regulators of gene expression and several miRNAs are associated with the development of T2DM. However, the expression and biological function of miRNA‑9‑3p in lipid metabolism of patients with T2DM remain to be fully elucidated. The predominant aim of the present study was to examine the effect of miRNA‑9‑3p on lipid accumulation in HepG2 cells. To investigate this, an MTT assay was used to determine cell proliferation, and the effects of miRNA‑9‑3p on triglycerides (TG) and total cholesterol (TC) in the HepG2 cells were also examined. Reverse transcription‑quantitative polymerase chain reaction and western blot analyses were used to measure the expression levels of SIRT1 at the gene and protein levels, respectively. The date revealed that downregulation of miRNA‑9‑3p inhibited the proliferation of HepG2 cells, and significantly reduced the accumulation of lipids, and decreased TG and TC content. In addition, the present study demonstrated that inhibition of miRNA‑9‑3p increased the protein expression of sirtuin type 1 (SIRT1), but had no effects on the gene expression of SIRT1. Therefore, these findings demonstrated that the inhibition of miRNA‑9‑3p reduced the proliferation of HepG2 cells and lipid accumulation by upregulating the expression of SIRT1, indicating its potential as a therapeutic target.

Polymorphism in microRNA-binding site in HNF1B influences the susceptibility of type 2 diabetes mellitus: a population based case-control study

Background

Recent genome-wide association studies (GWAS) have identified many SNPs associated with type 2 diabetes mellitus (T2DM). However, the functional roles for most of the SNPs have not been elucidated. MicroRNAs (miRNAs) are key regulators of gene expression involved in the development and progression of various diseases including T2DM. In this study, we investigated whether commonly occurring SNPs modulate miRNA-directed regulation of gene expression, and whether such SNPs in miRNA-binding sites are associated with the susceptibility for T2DM.

Methods

Genotypes of eleven 3′ untranslated region (UTR) SNPs of seven susceptibility genes for T2DM were determined in 353 T2DM patients and 448 control subjects. In addition, the interactions of miRNAs with the 3′UTR in the hepatocyte nuclear factor 1β (HNF1B) gene were investigated using luciferase reporter assays.

Results

One 3′UTR SNP (rs2229295) in the HNF1B gene was significantly associated with T2DM, and the frequency of an A allele (rs2229295) in T2DM patients was decreased compared with that in controls. Luciferase reporter assays showed that the SNP (rs2229295) altered the binding of two miRNAs (hsa-miR-214-5p and hsa-miR-550a-5p).

Conclusions

We have detected the interactions of hsa-miR-214-5p/hsa-miR-550a-5p and the 3′UTR SNP of the HNF1B gene by in vitro luciferase reporter assays, and propose that the binding of such miRNAs regulates the expression of the HNF1B gene and the susceptibility of T2DM.

Electronic supplementary material

The online version of this article (doi:10.1186/s12881-015-0219-5) contains supplementary material, which is available to authorized users.

Identification of microRNA biomarkers in type 2 diabetes: a meta-analysis of controlled profiling studies

AIMS/HYPOTHESIS

The aim was to identify potential microRNA (miRNA) biomarkers of type 2 diabetes.

METHODS

Controlled studies were retrieved from PubMed to compare miRNA expression profiles of type 2 diabetes and nondiabetic control samples. Meta-analysis under a random effects model was conducted. Subgroup analyses examined tissue specificity and species specificity. Sensitivity analyses were also performed to explain the heterogeneity among studies. Results were represented as log odds ratios (logOR), 95% confidence intervals (CI) and p values after Bonferroni correction.

RESULTS

Among 343 differentially expressed miRNAs in 38 miRNA expression profiling studies published between 1993 and March 2014, only 151 miRNAs were tested by multiple studies, out of which 102 miRNAs were reported to be upregulated or downregulated. Meta-analysis identified 51 significantly dysregulated miRNAs. The top upregulated miRNA was miR-142-3p (logOR 6.4721; 95% CI 4.9537, 7.9904; adjusted p = 4.60 × 10(-16)). The top downregulated miRNA was miR-126a (logOR 7.5237; 95% CI 4.7159, 10.3316; adjusted p = 3.01 × 10(-07)). The dysregulation of two miRNAs (miR-199a-3p and miR-223) was highly pancreas-specific and liver-specific. miR-30e was downregulated in patients with type 2 diabetes, while miR-92a was downregulated in animal models of diabetes. In sensitivity analysis, 40 out of 47 miRNAs (85%) were robustly and consistently dysregulated.

CONCLUSIONS/INTERPRETATION

This meta-analysis confirms that 40 miRNAs are significantly dysregulated in type 2 diabetes. miR-29a, miR-34a, miR-375, miR-103, miR-107, miR-132, miR-142-3p and miR-144 are potential circulating biomarkers of type 2 diabetes. In addition, miR-199a-3p and miR-223 are potential tissue biomarkers of type 2 diabetes.

Insulin promotes glucose consumption via regulation of miR-99a/mTOR/PKM2 pathway

Insulin is known to regulate multiple cellular functions and is used for the treatment of diabetes. MicroRNAs have been demonstrated to be involved in many human diseases, including Type 2 diabetes. In this study, we showed that insulin decreased miR-99a expression levels, but induced glucose consumption and lactate production, and increased the expression of mTOR, HIF-1α and PKM2 in HepG2 and HL7702 cells. Forced expression of miR-99a or rapamycin treatment blocked insulin-induced PKM2 and HIF-1α expression, and glucose consumption and lactate production. Meanwhile, knockdown of HIF-1α inhibited PKM2 expression and insulin-induced glucose consumption. Taken together, these findings will reveal the role and mechanism of insulin in regulating glycolytic activities via miR-99a/mTOR.