Multiple microRNAs within the 14q32 cluster target the mRNAs of major type 1 diabetes autoantigens IA-2, IA-2β, and GAD65

A set of circulating microRNAs belonging to the 14q32 chromosome locus identifies two subgroups of individuals with recent-onset type 1 diabetes

Circulating microRNAs (miRNAs) are linked to the onset and progression of type 1 diabetes mellitus (T1DM), thus representing potential disease biomarkers. In this study, we employed a multiplatform sequencing approach to analyze circulating miRNAs in an extended cohort of prospectively evaluated recent-onset T1DM individuals from the INNODIA consortium. Our findings reveal that a set of miRNAs located within T1DM susceptibility chromosomal locus 14q32 distinguishes two subgroups of individuals. To validate our results, we conducted additional analyses on a second cohort of T1DM individuals, confirming the identification of these subgroups, which we have named cluster A and cluster B. Remarkably, cluster B T1DM individuals, who exhibit increased expression of a set of 14q32 miRNAs, show better glycemic control and display a different blood immunomics profile. Our findings suggest that this set of circulating miRNAs can identify two different T1DM subgroups with distinct blood immunomics at baseline and clinical outcomes during follow-up.

Hereditable variants of classical protein tyrosine phosphatase genes: Will they prove innocent or guilty?

Protein tyrosine phosphatases, together with protein tyrosine kinases, control many molecular signaling steps that control life at cellular and organismal levels. Impairing alterations in the genes encoding the involved proteins is expected to profoundly affect the quality of life-if compatible with life at all. Here, we review the current knowledge on the effects of germline variants that have been reported for genes encoding a subset of the protein tyrosine phosphatase superfamily; that of the thirty seven classical members. The conclusion must be that the newest genome research tools produced an avalanche of data that suggest 'guilt by association' for individual genes to specific disorders. Future research should face the challenge to investigate these accusations thoroughly and convincingly, to reach a mature genotype-phenotype map for this intriguing protein family.

Genetic Indices Relationship to Hyperglycemia-associated Biomarkers: Consistency with miRNA Expression in Egyptian Children with T1DM

OBJECTIVE

Micro RNAs (miRNAs) are gaining acceptance as novel biomarkers for the autoimmune disorders. However, miRNA profiles have not been investigated in individuals at risk of or diagnosed with type 1 diabetes mellitus (T1DM). To study the expression pattern of miRNAs in plasma obtained from patients with T1DM and compare with matched healthy controls.

METHODS

Equal numbers of patients with T1DM (90) and healthy-matched control children (90) were assessed for the expression profile of plasma miRNAs including miRNA-101-5p, miRNA-146-5p, miRNA-21-5p, miRNA-375, miRNA-126, and Let7a-5p using reverse transcriptase polymerase chain reaction methodology and quantitative real-time testing.

RESULTS

Analysis showed that miRNA-101, miRNA-21 and miRNA-375 were highly expressed, whereas, miRNA-146-5p, miRNA-126, and miRNA-Let7a-5p showed significantly low levels of expression in T1DM patients compared to controls (p<0.05). In addition, miRNA-101 and miRNA-146 correlated with age at diagnosis of T1DM and disease duration, respectively. Furthermore, multivariate analysis showed that miRNA-126 and Let7a-5p had a significant negative correlation with mean hemoglobin A1c (HbA1c) values.

CONCLUSION

Dysregulation of the six miRNAs analyzed suggested a possible role as biomarkers in T1DM. miRNA-101 was correlated with age at diagnosis while miRNA-146 correlated with disease duration. Two further miRNAs correlated with the existing biomarker, HbA1c.

Honey polyphenolic fraction inhibits cyclooxygenase-2 expression via upregulation of microRNA-26a-5p expression in pancreatic islets

Objectives

Honey total polyphenolic fraction (HTPF) is reported to have anti-disease potential, however the role of HTPF in the regulation of microRNAs (miRNAs) has never been investigated. This study was undertaken to investigate the potential of HTPF against inflammation via regulation of miRNAs in pancreatic islets of Langerhans.

Methods

Pancreatic islets were isolated from C57BL/6 mice and HTPF was purified from honey. Bioinformatics algorithms were used to determine miRNA target genes. Expression of miRNA and mRNA was determined using their specific taqman assays. Pairing between miRNA and 3′ untranslated region (3′UTR) of mRNA was confirmed using luciferase reporter clone containing the 3′UTR of mRNA sequences and results were verified by transfection of mouse pancreatic β-cell line Min6 with miRNA inhibitors.

Results

The data showed that mmu-miR-26a-5p is a direct regulator of cyclooxygenase-2 (COX-2) expression and HTPF inhibits COX-2 expression or prostaglandin E2 (PGE2) production via up-regulating mmu-miR-26a-5p expression. Transfection of islets with anti-miR-26a-5p significantly enhanced COX-2 expression and PGE2 production ( p < .01), while HTPF treatment significantly inhibited anti-miR-26a-5p transfection-induced COX-2 expression or PGE2 production ( p < .05). These findings were further verified in pancreatic β-cells Min6. Moreover, the data also determined that HTPF also inhibits glucose-induced nuclear transcription factor (NF)-κB activity.

Conclusion

HTPF suppresses glucose-induced PGE2 production and activation of NF-κB via negative regulation of COX-2 and mmu-miR26a-5p. These novel pharmacological actions of HTPF on glucose-stimulated pancreatic islets provide new suggestions that HTPF or HTPF-derived compounds inhibit glucose induced inflammation in pancreas by up-regulating the expression of microRNAs.

Global miRNA expression reveals novel nuclear and mitochondrial interactions in Type 1 diabetes mellitus

BACKGROUND

Considering the potential role of miRNAs as biomarkers and their interaction with both nuclear and mitochondrial genes, we investigated the miRNA expression profile in type 1 diabetes (T1DM) patients, including the pathways in which they are involved considering both nuclear and mitochondrial functions.

METHODS

We analyzed samples of T1DM patients and control individuals (normal glucose tolerance) by high throughput miRNA sequencing (miRNome). Next, five miRNAs - hsa-miR-26b-5p, hsa-let-7i-5p, hsa-miR-143-3p, hsa-miR-501-3p and hsa-miR-100-5p - were validated by RT-qPCR. The identification of target genes was extracted from miRTarBase and mitoXplorer database. We also performed receiver operating characteristic (ROC) curves and miRNAs that had an AUC > 0.85 were considered potential biomarkers.

RESULTS

Overall, 41 miRNAs were differentially expressed in T1DM patients compared to control. Hsa-miR-21-5p had the highest number of predicted target genes and was associated with several pathways, including insulin signaling and apoptosis. 34.1% (14/41) of the differentially expressed miRNAs also targeted mitochondrial genes, and 80.5% (33/41) of them targeted nuclear genes involved in the mitochondrial metabolism. All five validated miRNAs were upregulated in T1DM. Among them, hsa-miR-26b-5p showed AUC>0.85, being suggested as potential biomarker to T1DM.

CONCLUSION

Our results demonstrated 41 DE miRNAs that had a great accuracy in discriminating T1DM and control group. Furthermore, we demonstrate the influence of these miRNAs on numerous metabolic pathways, including mitochondrial metabolism. Hsa-miR-26b-5p and hsa-miR-21-5p were highlighted in our results, possibly acting on nuclear and mitochondrial dysfunction and, subsequently, T1DM dysregulation.

Micro-RNA Implications in Type-1 Diabetes Mellitus: A Review of Literature

Type-1 diabetes mellitus (T1DM) is one of the most well-defined and complex metabolic disorders, characterized by hyperglycemia, with a constantly increasing incidence in children and adolescents. While current knowledge regarding the molecules related to the pathogenesis and diagnosis of T1DM is vast, the discovery of new molecules, such as micro ribonucleic acids (micro-RNAs, miRNAs), as well as their interactions with T1DM, has spurred novel prospects in the diagnosis of the disease. This review aims at summarizing current knowledge regarding miRNAs' biosynthesis and action pathways and their role as gene expression regulators in T1DM. MiRNAs follow a complex biosynthesis pathway, including cleaving and transport from nucleus to cytoplasm. After assembly of their final form, they inhibit translation or cause messenger RNA (mRNA) degradation, resulting in the obstruction of protein synthesis. Many studies have reported miRNA involvement in T1DM pathogenesis, mainly through interference with pancreatic b-cell function, insulin production and secretion. They are also found to contribute to β-cell destruction, as they aid in the production of autoreactive agents. Due to their elevated accumulation in various biological specimens, as well as their involvement in T1DM pathogenesis, their role as biomarkers in early preclinical T1DM diagnosis is widely hypothesized, with future studies concerning their diagnostic value deemed a necessity.

Essential Role of the 14q32 Encoded miRNAs in Endocrine Tumors

BACKGROUND

The 14q32 cluster is among the largest polycistronic miRNA clusters. miRNAs encoded here have been implicated in tumorigenesis of multiple organs including endocrine glands.

METHODS

Critical review of miRNA studies performed in endocrine tumors have been performed. The potential relevance of 14q32 miRNAs through investigating their targets, and integrating the knowledge provided by literature data and bioinformatics predictions have been indicated.

RESULTS

Pituitary adenoma, papillary thyroid cancer and a particular subset of pheochromocytoma and adrenocortical cancer are characterized by the downregulation of miRNAs encoded by the 14q32 cluster. Pancreas neuroendocrine tumors, most of the adrenocortical cancer and medullary thyroid cancer are particularly distinct, as 14q32 miRNAs were overexpressed. In pheochromocytoma and growth-hormone producing pituitary adenoma, however, both increased and decreased expression of 14q32 miRNAs cluster members were observed. In the background of this phenomenon methodological, technical and biological factors are hypothesized and discussed. The functions of 14q32 miRNAs were also revealed by bioinformatics and literature data mining.

CONCLUSIONS

14q32 miRNAs have a significant role in the tumorigenesis of endocrine organs. Regarding their stable expression in the circulation of healthy individuals, further investigation of 14q32 miRNAs could provide a potential for use as biomarkers (diagnostic or prognostic) in endocrine neoplasms.

Assessment of differentially methylated loci in individuals with end-stage kidney disease attributed to diabetic kidney disease: an exploratory study

BACKGROUND

A subset of individuals with type 1 diabetes mellitus (T1DM) are predisposed to developing diabetic kidney disease (DKD), the most common cause globally of end-stage kidney disease (ESKD). Emerging evidence suggests epigenetic changes in DNA methylation may have a causal role in both T1DM and DKD. The aim of this exploratory investigation was to assess differences in blood-derived DNA methylation patterns between individuals with T1DM-ESKD and individuals with long-duration T1DM but no evidence of kidney disease upon repeated testing to identify potential blood-based biomarkers. Blood-derived DNA from individuals (107 cases, 253 controls and 14 experimental controls) were bisulphite treated before DNA methylation patterns from both groups were generated and analysed using Illumina's Infinium MethylationEPIC BeadChip arrays (n = 862,927 sites). Differentially methylated CpG sites (dmCpGs) were identified (false discovery rate adjusted p ≤ × 10^-8 and fold change ± 2) by comparing methylation levels between ESKD cases and T1DM controls at single site resolution. Gene annotation and functionality was investigated to enrich and rank methylated regions associated with ESKD in T1DM.

RESULTS

Top-ranked genes within which several dmCpGs were located and supported by functional data with methylation look-ups in other cohorts include: AFF3, ARID5B, CUX1, ELMO1, FKBP5, HDAC4, ITGAL, LY9, PIM1, RUNX3, SEPTIN9 and UPF3A. Top-ranked enrichment pathways included pathways in cancer, TGF-β signalling and Th17 cell differentiation.

CONCLUSIONS

Epigenetic alterations provide a dynamic link between an individual's genetic background and their environmental exposures. This robust evaluation of DNA methylation in carefully phenotyped individuals has identified biomarkers associated with ESKD, revealing several genes and implicated key pathways associated with ESKD in individuals with T1DM.

Baseline Assessment of Circulating MicroRNAs Near Diagnosis of Type 1 Diabetes Predicts Future Stimulated Insulin Secretion

Type 1 diabetes is an autoimmune disease resulting in severely impaired insulin secretion. We investigated whether circulating microRNAs (miRNAs) are associated with residual insulin secretion at diagnosis and predict the severity of its future decline. We studied 53 newly diagnosed subjects enrolled in placebo groups of TrialNet clinical trials. We measured serum levels of 2,083 miRNAs, using RNA sequencing technology, in fasting samples from the baseline visit (<100 days from diagnosis), during which residual insulin secretion was measured with a mixed meal tolerance test (MMTT). Area under the curve (AUC) C-peptide and peak C-peptide were stratified by quartiles of expression of 31 miRNAs. After adjustment for baseline C-peptide, age, BMI, and sex, baseline levels of miR-3187-3p, miR-4302, and the miRNA combination of miR-3187-3p/miR-103a-3p predicted differences in MMTT C-peptide AUC/peak levels at the 12-month visit; the combination miR-3187-3p/miR-4723-5p predicted proportions of subjects above/below the 200 pmol/L clinical trial eligibility threshold at the 12-month visit. Thus, miRNA assessment at baseline identifies associations with C-peptide and stratifies subjects for future severity of C-peptide loss after 1 year. We suggest that miRNAs may be useful in predicting future C-peptide decline for improved subject stratification in clinical trials.

Innate Viral Sensor MDA5 and Coxsackievirus Interplay in Type 1 Diabetes Development

Type 1 diabetes (T1D) is a polygenic autoimmune disease characterized by immune-mediated destruction of insulin-producing β-cells. The concordance rate for T1D in monozygotic twins is ≈30-50%, indicating that environmental factors also play a role in T1D development. Previous studies have demonstrated that enterovirus infections such as coxsackievirus type B (CVB) are associated with triggering T1D. Prior to autoantibody development in T1D, viral RNA and antibodies against CVB can be detected within the blood, stool, and pancreata. An innate pathogen recognition receptor, melanoma differentiation-associated protein 5 (MDA5), which is encoded by the IFIH1 gene, has been associated with T1D onset. It is unclear how single nucleotide polymorphisms in IFIH1 alter the structure and function of MDA5 that may lead to exacerbated antiviral responses contributing to increased T1D-susceptibility. Binding of viral dsRNA via MDA5 induces synthesis of antiviral proteins such as interferon-alpha and -beta (IFN-α/β). Viral infection and subsequent IFN-α/β synthesis can lead to ER stress within insulin-producing β-cells causing neo-epitope generation, activation of β-cell-specific autoreactive T cells, and β-cell destruction. Therefore, an interplay between genetics, enteroviral infections, and antiviral responses may be critical for T1D development.

miR-409-3p is reduced in plasma and islet immune infiltrates of NOD diabetic mice and is differentially expressed in people with type 1 diabetes

AIMS/HYPOTHESIS

MicroRNAs (miRNAs) are a novel class of potential biomarkers emerging in many diseases, including type 1 diabetes. Here, we aim to analyse a panel of circulating miRNAs in non-obese diabetic (NOD) mice and individuals with type 1 diabetes.

METHODS

We adopted standardised methodologies for extracting miRNAs from small sample volumes to evaluate a profiling panel of mature miRNAs in paired plasma and laser-captured microdissected immune-infiltrated islets of recently diabetic and normoglycaemic NOD mice. Moreover, we validated the findings during disease progression and remission after anti-CD3 therapy in NOD mice, as well as in individuals with type 1 diabetes.

RESULTS

Plasma levels of five miRNAs were downregulated in diabetic vs normoglycaemic mice. Of those, miR-409-3p was also downregulated in situ in the immune islet infiltrates of diabetic mice, suggesting an association with disease pathogenesis. Target-prediction tools linked miR-409-3p to immune- and metabolism-related signalling molecules. In situ miR-409-3p expression correlated with insulitis severity, and CD8⁺ central memory T cells were found to be enriched in miR-409-3p. Plasma miR-409-3p levels gradually decreased during diabetes development and improved with disease remission after anti-CD3 antibody therapy. Finally, plasma miR-409-3p levels were lower in people recently diagnosed with type 1 diabetes compared with a non-diabetic control group, and levels were inversely correlated with HbA_1c levels.

CONCLUSIONS/INTERPRETATION

We propose that miR-409-3p may represent a new circulating biomarker of islet inflammation and type 1 diabetes severity.

Omics-based biomarkers in the diagnosis of diabetes

Diabetes mellitus (DM) is a group of metabolic diseases related to the dysfunction of insulin, causing hyperglycaemia and life-threatening complications. Current early screening and diagnostic tests for DM are based on changes in glucose levels and autoantibody detection. This review evaluates recent studies on biomarker candidates in diagnosing type 1, type 2 and gestational DM based on omics classification, whilst highlighting the relationship of these biomarkers with the development of diabetes, diagnostic accuracy, challenges and future prospects. In addition, it also focuses on possible non-invasive biomarker candidates besides common blood biomarkers.

MicroRNAs: markers of β-cell stress and autoimmunity

PURPOSE OF REVIEW

We discuss current knowledge about microRNAs (miRNAs) in type 1 diabetes (T1D), an autoimmune disease leading to severe loss of pancreatic β-cells. We describe: the role of cellular miRNAs in regulating immune functions and pathways impacting insulin secretion and β-cell survival; circulating miRNAs as disease biomarkers.

RECENT FINDINGS

Studies examined miRNAs in experimental models and patients, including analysis of tissues from organ donors, peripheral blood cells, and circulating miRNAs in serum, plasma, and exosomes. Studies employed diverse designs and methodologies to detect miRNAs and measure their levels. Selected miRNAs have been linked to the regulation of key biological pathways and disease pathogenesis; several circulating miRNAs are associated with having T1D, islet autoimmunity, disease progression, and immune and metabolic functions, for example, C-peptide secretion, in multiple studies.

SUMMARY

A growing literature reveals multiple roles of miRNAs in T1D, provide new clues into the regulation of disease mechanisms, and identify reproducible associations. Yet challenges remain, and the field will benefit from joint efforts to analyze results, compare methodologies, formally test the robustness of miRNA associations, and ultimately move towards validating robust miRNA biomarkers.

MicroRNA expression profile in plasma from type 1 diabetic patients: Case-control study and bioinformatic analysis

AIMS

To investigate a miRNA expression profile in plasma of type 1 diabetes (T1DM) patients and control subjects and analyze the putative pathways involved.

METHODS

Expressions of 48 miRNAs were analyzed in plasma of 33 T1DM patients and 26 age-and-gender-matched controls using Stem-loop RT-PreAmp PCR and TaqMan Low Density Arrays (Thermo Fisher Scientific). Five dysregulated miRNAs were then chosen for validation in an independent sample of 27 T1DM patients and 14 controls, using RT-qPCR. Bioinformatic analyses were performed to determine in which pathways these miRNAs are involved.

RESULTS

Nine miRNAs were differentially expressed between recently-diagnosed T1DM patients (<5 years of diagnosis) and controls. No differences were observed between patients with ≥5 years of diagnosis and controls. After validation in an independent sample of T1DM patients, miR-103a-3p, miR-155-5p, miR-200a-3p, and miR-210-3p were confirmed as being upregulated in recently-diagnosed T1DM patients compared with controls or patients with ≥5 years of diagnosis. Moreover, miR-146a-5p was downregulated in recently-diagnosed T1DM patients compared with the other groups. These five miRNAs regulate several genes from innate immune system-, MAPK-, apoptosis-, insulin- and cancer-related pathways.

CONCLUSION

Five miRNAs are dysregulated in recently-diagnosed T1DM patients and target several genes involved in pathways related to T1DM pathogenesis, thus representing potential T1DM biomarkers.

Expression of miR-155, miR-146a, and miR-326 in T1D patients from Chile: relationship with autoimmunity and inflammatory markers

Objective The aim of this research was to analyze the expression profile of miR-155, miR-146a, and miR-326 in peripheral blood mononuclear cells (PBMC) of 47 patients with type 1 diabetes mellitus (T1D) and 39 control subjects, as well as the possible association with autoimmune or inflammatory markers. Subjects and methods Expression profile of miRs by means of qPCR using TaqMan probes. Autoantibodies and inflammatory markers by ELISA. Statistical analysis using bivariate correlation. Results The analysis of the results shows an increase in the expression of miR-155 in T1D patients in basal conditions compared to the controls (p < 0.001) and a decreased expression level of miR-326 (p < 0.01) and miR-146a (p < 0.05) compared T1D patients to the controls. miR-155 was the only miRs associated with autoinmmunity (ZnT8) and inflammatory status (vCAM). Conclusion Our data show a possible role of miR-155 related to autoimmunity and inflammation in Chilean patients with T1D.

Clustered miRNAs and their role in biological functions and diseases

MicroRNAs (miRNAs) are endogenous, small non-coding RNAs known to regulate expression of protein-coding genes. A large proportion of miRNAs are highly conserved, localized as clusters in the genome, transcribed together from physically adjacent miRNAs and show similar expression profiles. Since a single miRNA can target multiple genes and miRNA clusters contain multiple miRNAs, it is important to understand their regulation, effects and various biological functions. Like protein-coding genes, miRNA clusters are also regulated by genetic and epigenetic events. These clusters can potentially regulate every aspect of cellular function including growth, proliferation, differentiation, development, metabolism, infection, immunity, cell death, organellar biogenesis, messenger signalling, DNA repair and self-renewal, among others. Dysregulation of miRNA clusters leading to altered biological functions is key to the pathogenesis of many diseases including carcinogenesis. Here, we review recent advances in miRNA cluster research and discuss their regulation and biological functions in pathological conditions.

MicroRNAs in type 1 diabetes: new research progress and potential directions

MicroRNAs (miRNAs) are a class of noncoding single-stranded RNA molecules encoded by endogenous genes of about 22 nucleotides, which are involved in post-transcriptional gene expression regulation in animals and plants. Type 1 diabetes (T1D) is an autoimmune disease that is clinically silent until the majority of β cells are destroyed, and a large number of studies have shown that miRNAs are involved in the pathological mechanism of T1D. In this review, we searched the related research in recent years and summarized the important roles of miRNAs in T1D diagnosis and treatment. Furthermore, we summarized the current understanding of miRNA-mediated regulation mechanisms of gene expression in the T1D pathogenesis as well as related signaling pathways with a focus on the important roles of miRNAs and their antagonists in T1D pathogenesis, and brought insight into the potential therapeutic value of miRNAs for T1D patients. In view of the important roles of miRNAs in T1D pathology, disordered miRNAs may be important diagnostic markers and therapeutic targets for patients with T1D.

DICER1 gene mutations in endocrine tumors

In this review, the importance of the DICER1 gene in the function of endocrine cells is discussed. There is conclusive evidence that DICER1 mutations play a crucial role in the development, progression, cell proliferation, therapeutic responsiveness and behavior of several endocrine tumors. We review the literature of DICER1 gene mutations in thyroid, parathyroid, pituitary, pineal gland, endocrine pancreas, paragangliomas, medullary, adrenocortical, ovarian and testicular tumors. Although significant progress has been made during the last few years, much more work is needed to fully understand the significance of DICER1 mutations.

Serum miRNA levels are related to glucose homeostasis and islet autoantibodies in children with high risk for type 1 diabetes

Micro RNAs (miRNAs) are promising disease biomarkers due to their high stability. Their expression in serum is altered in type 1 diabetes, but whether deviations exist in individuals with high risk for type 1 diabetes remains unexplored. We therefore assessed serum miRNAs in high-risk individuals (n = 21) positive for multiple islet autoantibodies, age-matched healthy children (n = 17) and recent-onset type 1 diabetes patients (n = 8), using Serum/Plasma Focus microRNA PCR Panels from Exiqon. The miRNA levels in the high-risk group were similar to healthy controls, and no specific miRNA profile was identified for the high-risk group. However, serum miRNAs appeared to reflect glycemic status and ongoing islet autoimmunity in high-risk individuals, since several miRNAs were associated to glucose homeostasis and autoantibody titers. High-risk individuals progressing to clinical disease after the sampling could not be clearly distinguished from non-progressors, while miRNA expression in the type 1 diabetes group deviated significantly from high-risk individuals and healthy controls, perhaps explained by major metabolic disturbances around the time of diagnosis.

MicroRNA expression profiles and type 1 diabetes mellitus: systematic review and bioinformatic analysis

Growing evidence indicates that microRNAs (miRNAs) have a key role in processes involved in type 1 diabetes mellitus (T1DM) pathogenesis, including immune system functions and beta-cell metabolism and death. Although dysregulated miRNA profiles have been identified in T1DM patients, results are inconclusive; with only few miRNAs being consistently dysregulated among studies. Thus, we performed a systematic review of the literature on the subject, followed by bioinformatic analysis, to point out which miRNAs are dysregulated in T1DM-related tissues and in which pathways they act. PubMed and EMBASE were searched to identify all studies that compared miRNA expressions between T1DM patients and non-diabetic controls. Search was completed in August, 2017. Those miRNAs consistently dysregulated in T1DM-related tissues were submitted to bioinformatic analysis, using six databases of miRNA-target gene interactions to retrieve their putative targets and identify potentially affected pathways under their regulation. Thirty-three studies were included in the systematic review: 19 of them reported miRNA expressions in human samples, 13 in murine models and one in both human and murine samples. Among 278 dysregulated miRNAs reported in these studies, 25.9% were reported in at least 2 studies; however, only 48 of them were analyzed in tissues directly related to T1DM pathogenesis (serum/plasma, pancreas and peripheral blood mononuclear cells (PBMCs)). Regarding circulating miRNAs, 11 were consistently dysregulated in T1DM patients compared to controls: miR-21-5p, miR-24-3p, miR-100-5p, miR-146a-5p, miR-148a-3p, miR-150-5p, miR-181a-5p, miR-210-5p, miR-342-3p, miR-375 and miR-1275. The bioinformatic analysis retrieved a total of 5867 validated and 2979 predicted miRNA-target interactions for human miRNAs. In functional enrichment analysis of miRNA target genes, 77 KEGG terms were enriched for more than one miRNA. These miRNAs are involved in pathways related to immune system function, cell survival, cell proliferation and insulin biosynthesis and secretion. In conclusion, eleven circulating miRNAs seem to be dysregulated in T1DM patients in different studies, being potential circulating biomarkers of this disease.

Association of serum microRNAs with islet autoimmunity, disease progression and metabolic impairment in relatives at risk of type 1 diabetes

AIMS/HYPOTHESIS

MicroRNAs (miRNAs) are key regulators of gene expression and novel biomarkers for many diseases. We investigated the hypothesis that serum levels of some miRNAs would be associated with islet autoimmunity and/or progression to type 1 diabetes.

METHODS

We measured levels of 93 miRNAs most commonly detected in serum. This retrospective cohort study included 150 autoantibody-positive and 150 autoantibody-negative family-matched siblings enrolled in the TrialNet Pathway to Prevention Study. This was a young cohort (mean age = 11 years), and most autoantibody-positive relatives were at high risk because they had multiple autoantibodies, with 39/150 (26%, progressors) developing type 1 diabetes within an average 8.7 months of follow-up. We analysed miRNA levels in relation to autoantibody status, future development of diabetes and OGTT C-peptide and glucose indices of disease progression.

RESULTS

Fifteen miRNAs were differentially expressed when comparing autoantibody-positive/negative siblings (range -2.5 to 1.3-fold). But receiver operating characteristic (ROC) analysis indicated low specificity and sensitivity. Seven additional miRNAs were differentially expressed among autoantibody-positive relatives according to disease progression; ROC returned significant AUC values and identified miRNA cut-off levels associated with an increased risk of disease in both cross-sectional and survival analyses. Levels of several miRNAs showed significant correlations (r values range 0.22-0.55) with OGTT outcomes. miR-21-3p, miR-29a-3p and miR-424-5p had the most robust associations.

CONCLUSIONS/INTERPRETATION

Serum levels of selected miRNAs are associated with disease progression and confer additional risk of the development of type 1 diabetes in young autoantibody-positive relatives. Further studies, including longitudinal assessments, are warranted to further define miRNA biomarkers for prediction of disease risk and progression.

Association Analysis of Single Nucleotide Polymorphisms in C1QTNF6, RAC2, and an Intergenic Region at 14q32.2 with Graves' Disease in Chinese Han Population

BACKGROUND

Variation within the C1QTNF6 gene at 22q12.3, the RAC2 gene at 22q13.1, and an intergenic region at 14q32.2 were found to be associated with risk to Graves' disease (GD) in a recent study. We aimed to validate these associations with GD in an independent sample set of Han Chinese population.

METHODS

We investigated these associations by genotyping the most significantly associated single nucleotide polymorphisms (SNPs) located in these three regions. Rs1456988 within the intergenic region at 14q32.2, rs229527 within C1QTNF6 at 22q12.3, and rs2284038 within RAC2 at 22q13.1 were selected for genotyping. These three SNPs were genotyped using a case-control study that included 2382 GD patients and 3092 unrelated healthy controls from Northern Han Chinese ancestry. The genotyping was performed using TaqMan assays on the ABI7900 platform.

RESULTS

We found both the rs229527 allele within C1QTNF6 (odds ratio [OR] = 1.23, confidence interval [95% CI]: 1.12-1.33, pAllelic = 4.60 × 10-6) and the rs2284038 allele within RAC2 (OR = 1.10, 95% CI: 1.01-0.19, pAllelic = 3.00 × 10-2) showed significant associations with GD susceptibility. However, rs1456988 located in 14q32.2 (OR = 1.08, 95% CI: 0.99-1.16, pAllelic = 7.01 × 10-2) showed no association. Analysis of models of inheritance suggested that both the dominant and recessive models showed significant associations for rs229527 (OR = 1.24, 95% CI: 1.13-1.38, pDominant = 9.90 × 10-5; OR = 1.49, 95% CI: 1.19-1.86, pRecessive = 3.90 × 10-4), with the dominant model being preferred. For rs2284038, the recessive model was preferred (OR = 1.18, 95% CI: 1.00-1.40, pRecessive = 4.76 × 10-2), whereas analysis of dominant model showed no association (OR = 1.10, 95% CI: 0.98-1.22, pDominant = 0.10).

CONCLUSIONS

Our findings confirmed that chromosome 22q12.3 and 22q13.1 variants are associated with GD in an independent Han Chinese population; however, 14q32.2 showed no association with GD.

miRNAs: novel regulators of autoimmunity-mediated pancreatic β-cell destruction in type 1 diabetes

MicroRNAs (miRNAs) are a series of conserved, short, non-coding RNAs that modulate gene expression in a posttranscriptional manner. miRNAs are involved in almost every physiological and pathological process. Type 1 diabetes (T1D) is an autoimmune disease that is the result of selective destruction of pancreatic β-cells driven by the immune system. miRNAs are also important participants in T1D pathogenesis. Herein, we review the most recent data on the potential involvement of miRNAs in T1D. Specifically, we focus on two aspects: the roles of miRNAs in maintaining immune homeostasis and regulating β-cell survival and/or functions in T1D. We also discuss circulating miRNAs as potent biomarkers for the diagnosis and prediction of T1D and investigate potential therapeutic approaches for this disease.

MicroRNA expression profiles of human iPSCs differentiation into insulin-producing cells

AIMS

MicroRNAs are a class of small noncoding RNAs, which control gene expression by inhibition of mRNA translation. MicroRNAs are involved in the control of biological processes including cell differentiation. Here, we aim at characterizing microRNA expression profiles during differentiation of human induced pluripotent stem cells (hiPSCs) into insulin-producing cells.

METHODS

We differentiated hiPSCs toward endocrine pancreatic lineage following a 18-day protocol. We analyzed genes and microRNA expression levels using RT real-time PCR and TaqMan microRNA arrays followed by bioinformatic functional analysis.

RESULTS

MicroRNA expression profiles analysis of undifferentiated hiPSCs during pancreatic differentiation revealed that 347/768 microRNAs were expressed at least in one time point of all samples. We observed 18 microRNAs differentially expressed: 11 were upregulated (miR-9-5p, miR-9-3p, miR-10a, miR-99a-3p, miR-124a, miR-135a, miR-138, miR-149, miR-211, miR-342-3p and miR-375) and 7 downregulated (miR-31, miR-127, miR-143, miR-302c-3p, miR-373, miR-518b and miR-520c-3p) during differentiation into insulin-producing cells. Selected microRNAs were further evaluated during differentiation of Sendai-virus-reprogrammed hiPSCs using an improved endocrine pancreatic beta cell derivation protocol and, moreover, in differentiated NKX6.1⁺ sorted cells. Following Targetscan7.0 analysis of target genes of differentially expressed microRNAs and gene ontology classification, we found that such target genes belong to categories of major significance in pancreas organogenesis and development or exocytosis.

CONCLUSIONS

We detected a specific hiPSCs microRNAs signature during differentiation into insulin-producing cells and demonstrated that differentially expressed microRNAs target several genes involved in pancreas organogenesis.

Small cell lung cancer growth is inhibited by miR-342 through its effect of the target gene IA-2

Background

Small cell lung cancers (SCLC) are tumors of neuroendocrine origin. Previous in vitro studies from our laboratory showed that SCLC expresses high levels of the transmembrane dense core vesicle protein IA-2 (islet cell antigen-2) as compared to normal lung cells. IA-2, through its effect on dense core vesicles (DCVs), is known to be involved in the secretion of hormones and neurotransmitters. It is believed that the dysregulated release of the neurotransmitter Acetylcholine (ACh) by DCVs has an autocrine effect on SCLC cell growth. Recently, we found that IA-2 is a target of the microRNA miR-342 and that miR-342 mimics suppress the expression of IA-2. The present experiments were initiated to see whether IA-2 and/or miR-342 affect the growth of SCLC.

Methods

SCLC cell growth was evaluated following the knockdown of endogenous IA-2 with RNAi or by overexpressing miR-342 with a mimic. The secretion and content of ACh in SCLC cells was analyzed using a human acetylcholine ELISA (enzyme-linked immunosorbent assay) kit.

Results

The knockdown of endogenous IA-2 by RNAi reduced SCLC cell growth within 4 days by 40 % or more. Similar results were obtained when these cell lines were transfected with a miR-342 mimic. The knockdown of IA-2 by RNAi or miR-342 with a mimic also resulted in a significant decrease in the secretion of ACh, one of the autocrine hormones secreted by SCLC. Further studies revealed that the growth of SCLC cell lines that had been treated with the miR-342 mimic was restored to nearly normal levels by treatment with ACh.

Conclusion

Our studies show for the first time that both miR-342 and its target gene IA-2 are involved in the growth process of SCLC cells and act by their effect on autocrine secretion. These findings point to possible new therapeutic approaches for the treatment of autocrine-induced tumor proliferation.