The role of microRNAs in islet β-cell development

Targeted Resequencing Identifies Novel MAFB Variants Associated With Nonsyndromic Cleft Lip With or Without Cleft Palate

ObjectivesNonsyndromic cleft lip with or without palate (NSCL/P) is one of the most prevalent congenital orofacial defects. It arises from a combination of genetic and environmental factors. This study aims to identify new risk loci around the musculoaponeurotic fibrosarcoma oncogene family, protein B (MAFB) gene in NSCL/P patients from the Western Han Chinese population.DesignA targeted region sequencing approach was employed to examine the MAFB gene in 159 NSCL/P cases. We conducted both single-variant association and gene-based burden analyses.SettingThe study was conducted in a stomatological hospital.Patients, participantsOne hundred and fifty-nine NSCL/P cases were analyzed.InterventionsBlood samples were collected.Main outcome measuresTo explore the association analysis between variants at MAFB and NSCL/P in Western Han Chinese population.ResultsWe identified a cluster of significant common variants near the 3' end of MAFB. Notably, rs6029223 showed significantly associated with NSCL/P (P = 3.82E-09, odds ration [OR] = 0.29, 95% confidence interval [CI]: 0.18-0.46), nonsyndromic cleft lip and palate (NSCLP) (P = 5.31E-08, OR = 0.25, 95% CI: 0.14-0.44) and nonsyndromic cleft lip only (NSCLO) (P = 1.3E-04, OR = 0.34, 95%CI: 0.19-0.62). In Addition, rs79836852 and rs200392238 were significantly associated with both NSCL/P and NSCLP.ConclusionsOur study revealed that single nucleotide polymorphisms near the 3' end of the MAFB gene are risk factors for NSCL/P and NSCLP in the Western Han Chinese population. Our findings reinforce the notion that MAFB is a susceptibility gene for NSCL/P.

Insights into the development of insulin-producing cells: Precursors correlated involvement of microRNA panels

Type 1 diabetes (T1D) is a chronic autoimmune condition characterized by the destruction of pancreatic β cells, recently estimated to affect approximately 8.75 million individuals worldwide. At variance with conventional management of T1D, which relies on exogenous insulin replacement and insulinotropic drugs, emerging therapeutic strategies include transplantation of insulin-producing cells (IPCs) derived from stem cells or fully reprogrammed differentiated cells. Through the in-depth analysis of the microRNAs (miRNAs) involved in the differentiation of human embryonic stem cells (ESCs), mesenchymal stem cells (MSCs), and induced pluripotent stem cells (iPSCs), into insulin-producing cells, this review provides a comprehensive overview of the molecular mechanisms orchestrating the transformation of precursors to cells producing insulin. In addition to miR-375, involved in all differentiation processes, and to miR-7, mir-145 and miR-9, common to the generation of insulin-producing cells from at least two different sources, the literature reveals panels of miRNAs closely related to precursor cells and associated with specific events of the physiological β cell maturation. Since the forced modulation of miRNAs can direct cells development towards insulin-producing cells or modify their fate, a more comprehensive knowledge of the miRNAs involved in the cellular events leading to obtain efficient β cells could improve the diagnostic, prognostic, and therapeutic approaches to diabetes.

The role of pyroptosis in metabolism and metabolic disease

Pyroptosis is a lytic and pro-inflammatory form of regulated cell death characterized by the formation of membrane pores mediated by the gasdermin protein family. Two main activation pathways have been documented: the caspase-1-dependent canonical pathway and the caspase-4/5/11-dependent noncanonical pathway. Pyroptosis leads to cell swelling, lysis, and the subsequent release of inflammatory mediators, including interleukin-1β (IL-1β) and interleukin-18 (IL-18). Chronic inflammation is a well-established foundation and driver for the development of metabolic diseases. Conversely, metabolic pathway dysregulation can also induce cellular pyroptosis. Recent studies have highlighted the significant role of pyroptosis modulation in various metabolic diseases, including type 2 diabetes mellitus, obesity, and metabolic (dysfunction) associated fatty liver disease. These findings suggest that pyroptosis may serve as a promising novel therapeutic target for metabolic diseases. This paper reviews an in-depth study of the current advancements in understanding the role of pyroptosis in the progression of metabolic diseases.

Extracellular miRNAs in the serum and feces of mice exposed to high‑dose radiation

Exposure to high-dose radiation causes life-threatening intestinal damage. Histopathology is the most accurate method of judging the extent of intestinal damage following death. However, it is difficult to predict the extent of intestinal damage. The present study investigated extracellular microRNAs (miRNAs or miRs) in serum and feces using a radiation-induced intestinal injury mouse model. A peak of 25-200 nucleotide small RNAs was detected in mouse serum and feces by bioanalyzer, indicating the presence of miRNAs. Microarray analysis detected four miRNAs expressed in the small intestine and increased by >2-fold in serum and 19 in feces following 10 Gy radiation exposure. Increased miR-375-3p in both serum and feces suggests leakage due to radiation-induced intestinal injury and may be a candidate for high-dose radiation biomarkers.

Reassessing the Abundance of miRNAs in the Human Pancreas and Rodent Cell Lines and Its Implication

miRNAs are critical for pancreas development and function. However, we found that there are discrepancies regarding pancreatic miRNA abundance in published datasets. To obtain a more relevant profile that is closer to the true profile, we profiled small RNAs from human islets cells, acini, and four rodent pancreatic cell lines routinely used in diabetes and pancreatic research using a bias reduction protocol for small RNA sequencing. In contrast to the previous notion that miR-375-3p is the most abundant pancreatic miRNA, we found that miR-148a-3p and miR-7-5p were also abundant in islets. In silico studies using predicted and validated targets of these three miRNAs revealed that they may work cooperatively in endocrine and exocrine cells. Our results also suggest, compared to the most-studied miR-375, that both miR-148a-3p and miR-7-5p may play more critical roles in the human pancreas. Moreover, according to in silico-predicted targets, we found that miR-375-3p had a much broader target spectrum by targeting the coding sequence and the 5' untranslated region, rather than the conventional 3' untranslated region, suggesting additional unexplored roles of miR-375-3p beyond the pancreas. Our study provides a valuable new resource for studying miRNAs in pancreata.

Non-coding RNAs: The link between maternal malnutrition and offspring metabolism

Early life nutrition is associated with the development and metabolism in later life, which is known as the Developmental Origin of Health and Diseases (DOHaD). Epigenetics have been proposed as an important explanation for this link between early life malnutrition and long-term diseases. Non-coding RNAs (ncRNAs) may play a role in this epigenetic programming. The expression of ncRNAs (such as long non-coding RNA H19, microRNA-122, and circular RNA-SETD2) was significantly altered in specific tissues of offspring exposed to maternal malnutrition. Changes in these downstream targets of ncRNAs lead to abnormal development and metabolism. This review aims to summarize the existing knowledge on ncRNAs linking the maternal nutrition condition and offspring metabolic diseases, such as obesity, type 2 diabetes (T2D) and non-alcoholic fatty liver disease (NAFLD).

Sox6, A Potential Target for MicroRNAs in Cardiometabolic Disease

PURPOSE OF REVIEW

The study aims to review recent advances in knowledge on the interplay between miRNAs and the sex-determining Region Y (SRY)-related high-mobility-group box 6 (Sox6) in physiology and pathophysiology, highlighting an important role in autoimmune and cardiometabolic conditions.

RECENT FINDINGS

The transcription factor Sox6 is an important member of the SoxD family and plays an indispensable role in adult tissue homeostasis, regeneration, and physiology. Abnormal expression of the Sox6 gene has been implicated in several disease conditions including diabetes, cardiomyopathy, autoimmune diseases, and hypertension. Expression of Sox6 is regulated by miRNAs, which are RNAs of about 22 nucleotides, and have also been implicated in several pathophysiological conditions where Sox6 plays a role. Regulation of Sox6 by miRNAs is important in diverse physiological tissues and organs. Dysregulation of the interplay between miRNAs and Sox6 is an important determinant of various disease conditions and may be actionable for therapeutic purposes.

MiR-17-5p Inhibits TXNIP/NLRP3 Inflammasome Pathway and Suppresses Pancreatic β-Cell Pyroptosis in Diabetic Mice

Objective: Diabetes mellitus is a chronic progressive inflammatory metabolic disease with pancreatic β-cells dysfunction. The present study aimed to investigate whether miR-17-5p plays a protective effect on pancreatic β-cells function in diabetes mellitus (DM) mice and dissect the underlying mechanism.

Methods: C57BL/6J mice were randomly divided into control, DM, DM + Lentivirus negative control (LV-NC), and DM + Lenti-OE™ miR-17-5p (LV-miR-17-5) groups. DM was established by feeding a high-fat diet and intraperitoneal injection with streptozotocin (STZ) in mice. Blood glucose and glucose tolerance in circulation were measured. Meanwhile, the activation of nod-like receptor protein 3 (NLRP3) inflammasome, pancreas pyroptosis, and the expression of miR-17-5p and thioredoxin-interacting protein (TXNIP) were detected in the pancreas of DM mice. Pancreatic β-cell line INS-1 subjected to different concentrations of glucose was used in in vitro experiments.

Results: Compared with control mice, glucose tolerance deficit, elevated blood glucose level, and decreased pancreatic islet size, were presented in DM mice, which was associated with a downregulation of miR-17-5p. Importantly, exogenous miR-17-5p alleviated pancreas injury, and consequently improved glucose tolerance and decreased blood glucose in DM mice. In vitro experiments showed that high glucose decreased miR-17-5p expression and impaired insulin secretion in INS-1 cells. Mechanistically, miR-17-5p inhibited the expression of TXNIP and NLRP3 inflammasome activation, and thus decreased pancreatic β-cell pyroptosis.

Conclusion: Our results demonstrated that miR-17-5p improves glucose tolerance, and pancreatic β-cell function and inhibits TXNIP/NLRP3 inflammasome pathway-related pyroptosis in DM mice.

The association of circulating miR-191 and miR-375 expression levels with markers of insulin resistance in overweight children: an exploratory analysis of the I.Family Study

Background

In recent years, the exciting emergence of circulating miRNAs as stable, reproducible, and consistent among individuals has opened a promising research opportunity for the detection of non-invasive biomarkers. A firm connection has been established between circulating miRNAs and glycaemic as well as metabolic homeostasis, showing that levels of specific miRNAs vary under different physio-pathological conditions.

Objective

In this pilot study, we investigated the expression of candidate miRNAs, hsa-miR-191-3p and hsa-miR-375, in relation to biomarkers associated with insulin sensitivity in a subgroup (n=58) of subjects participating to the European I.Family Study, a project aimed to assess the determinants of eating behaviour in children and adolescents and related health outcomes. The sample included overweight/obese children/adolescents since overweight/obesity is a known risk factor for impaired glucose homeostasis and metabolic disorders. Biological targets of candidate miRNAs were also explored in silico.

Results

We observed a significant association of the two miRNAs and early changes in glycaemic homeostasis, independent of covariates including country of origin, age, BMI z-score, puberty status, highest educational level of parents, total energy intake, energy from fats, energy from carbohydrates, and energy from proteins.

Conclusion

Identification of circulating miRNAs associated with insulin impairment may offer novel approaches of assessing early variations in insulin sensitivity and provide evidence about the molecular mechanisms connected to early changes in glycaemic homeostasis.

Trial registration

ISRCTN, ISRCTN62310987. Retrospectively registered, http://isrctn.com/ISRCTN62310987

Supplementary Information

The online version contains supplementary material available at 10.1186/s12263-021-00689-1.

miR-375 Promotes Pancreatic Differentiation In Vitro by Affecting Different Target Genes at Different Stages

Human embryonic stem cells (hESCs) possess the ability to differentiate into insulin-producing cells (IPCs), which can be used to treat type I diabetes. miR-375 is an essential transcriptional regulator in the development and maturation of the pancreas. In this study, we optimized a protocol to differentiate hESCs into IPCs and successfully obtained IPCs. Then, we performed overexpression and inhibition experiments of miR-375 on cells at different stages of differentiation and performed RNA-seq. The results showed that the expression of miR-375 fluctuated during hESC differentiation and was affected by miR-375 mimics and inhibitors. miR-375 influences global gene expression and the target genes of miR-375. The overexpression of miR-375 can cause changes in multiple signaling pathways during pancreatic development. miR-375 is a major participant in the differentiation of pancreatic β-cells through different target genes at different stages. This study provides new ideas for further investigation of how microRNAs affect cell fate and gene transcription.

The Predominant microRNAs in β-cell Clusters for Insulin Regulation and Diabetic Control

micro (mi)-RNAs are vital regulators of multiple processes including insulin signaling pathways and glucose metabolism. Pancreatic β-cells function is dependent on some miRNAs and their target mRNA, which together form a complex regulative network. Several miRNAs are known to be directly involved in β-cells functions such as insulin expression and secretion. These small RNAs may also play significant roles in the fate of β-cells such as proliferation, differentiation, survival and apoptosis. Among the miRNAs, miR-7, miR-9, miR-375, miR-130 and miR-124 are of particular interest due to being highly expressed in these cells. Under diabetic conditions, although no specific miRNA profile has been noticed, the expression of some miRNAs and their target mRNAs are altered by posttranscriptional mechanisms, exerting diverse signs in the pathobiology of various diabetic complications. The aim of this review article is to discuss miRNAs involved in the process of stem cells differentiation into β-cells, resulting in enhanced β-cell functions with respect to diabetic disorders. This paper will also look into the impact of miRNA expression patterns on in vitro proliferation and differentiation of β-cells. The efficacy of the computational genomics and biochemical analysis to link the changes in miRNA expression profiles of stem cell-derived β-cells to therapeutically relevant outputs will be discussed as well.

The Role of MicroRNAs in the Induction of Pancreatic Differentiation

Stem cell-based therapy is one of the therapeutic options with promising results in the treatment of diabetes. Stem cells from various sources are expanded and induced to generate the cells capable of secreting insulin. These insulin-producing cells [IPCs] could be used as an alternative to islets in the treatment of patients with diabetes. Soluble growth factors, small molecules, geneencoding transcription factors, and microRNAs [miRNAs] are commonly used for the induction of stem cell differentiation. MiRNAs are small non-coding RNAs with 21-23 nucleotides that are involved in the regulation of gene expression by targeting multiple mRNA targets. Studies have shown the dynamic expression of miRNAs during pancreatic development and stem cell differentiation. MiR- 7 and miR-375 are the most abundant miRNAs in pancreatic islet cells and play key roles in pancreatic development as well as islet cell functions. Some studies have tried to use these small RNAs for the induction of pancreatic differentiation. This review focuses on the miRNAs used in the induction of stem cells into IPCs and discusses their functions in pancreatic β-cells.

Exosomes from β-Cells Promote Differentiation of Induced Pluripotent Stem Cells into Insulin-Producing Cells Through microRNA-Dependent Mechanisms

OBJECTIVE

Exosomes have emerged as potential tools for the differentiation of induced pluripotent stem cells (iPSCs) into insulin-producing cells (IPCs). Exosomal microRNAs are receiving increasing attention in this process. Here, we aimed at investigating the role of exosomes derived from a murine pancreatic β-cell line and identifying signature exosomal miRNAs on iPSCs differentiation.

METHODS

Exosomes were isolated from MIN6 cells and identified with TEM, NTA and Western blot. PKH67 tracer and transwell assay were used to confirm exosome delivery into iPSCs. qRT-PCR was applied to detect key pancreatic transcription gene expression and exosome-derived miRNA expression. Insulin secretion was determined using FCM and immunofluorescence. The specific exosomal miRNAs were determined via RNA-interference of Ago2. The therapeutic effect of 21 day-exosome-induced IPCs was validated in T1D mice induced by STZ.

RESULTS

iPSCs cultured in medium containing exosomes showed sustained higher expression of MAFA, Insulin1, Insulin2, Isl1, Neuroud1, Nkx6.1 and NGN3 compared to control iPSCs. In FCM analysis, approximately 52.7% of the differentiated cells displayed insulin expression at the middle stage. Consistent with the gene expression data, immunofluorescence assays showed that Nkx6.1 and insulin expression in iPSCs were significantly upregulated. Intriguingly, the expression of pancreatic markers and insulin was significantly decreased in iPSCs cultured with siAgo2 exosomes. Transplantation of 21 day-induced IPCs intoT1D mice efficiently enhanced glucose tolerance and partially controlled hyperglycemia. The therapeutic effect was significantly attenuated in T1D mice that received iPSCs cultured with siAgo2 exosomes. Of the seven exosomal microRNAs selected for validation, miR-706, miR-709, miR-466c-5p, and miR-423-5p showed dynamic expression during 21 days in culture.

CONCLUSION

These data indicate that differentiation of exosome-induced iPSCs into functional cells is crucially dependent on the specific miRNAs encased within exosomes, whose functional analysis is likely to provide insight into novel regulatory mechanisms governing iPSCs differentiation into IPCs.

Therapeutic Potentials of MicroRNAs for Curing Diabetes Through Pancreatic β-Cell Regeneration or Replacement

MicroRNAs are a type of noncoding RNAs that regulates the expression of target genes at posttranscriptional level. MicroRNAs play essential roles in regulating the expression of different genes involved in pancreatic development, β-cell mass maintenance, and β-cell function. Alteration in the level of miRNAs involved in β-cell function leads to the diabetes. Being an epidemic, diabetes threatens the life of millions of patients posing a pressing demand for its urgent resolve. However, the currently available therapies are not substantial to cure the diabetic epidemic. Thus, researchers are trying to find new ways to replenish the β-cell mass in patients with diabetes. One promising approach is the in vivo regeneration of β-cell mass or increasing the efficiency of β-cell function. Another clinical strategy is the transplantation of in vitro developed β-like cells. Owing to their role in pancreatic β-cell development, maintenance, functioning and their involvement in diabetes, overexpression or attenuation of different miRNAs can cause β-cell regeneration in vivo or can direct the differentiation of various kinds of stem/progenitor cells to β-like cells in vitro. Here, we will summarize different strategies used by researchers to investigate the therapeutic potentials of miRNAs, with focus on miR-375, for curing diabetes through β-cell regeneration or replacement.

Association of miR-146a polymorphism rs2910164 and type 2 diabetes risk: a meta-analysis

OBJECTIVE

Circulating miR-146a is aberrantly expressed in patients with type 2 diabetes (T2D), probably resulting from gene polymorphisms. However, the role of polymorphism rs2910164 in T2D pathogenesis remains controversial. Thus, we designed a meta-analysis to investigate the association between rs2910164 and T2D.

METHODS

PubMed and Embase were searched for eligible papers in English published through September 2, 2019. Random or fixed effect models were used to determine risk estimates according to heterogeneities.

RESULTS

Four studies, involving 2,069 patients and 1,950 controls, were included. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were used to pool the effect size. The pooled ORs and 95% CIs were 1.501 (0.887-2.541), 1.102 (0.931-1.304), 1.276 (0.900-1.811), 1.204 (0.878-1.652), 1.238 (0.880-1.740), and 1.350 (0.904-2.016) under the homozygote, heterozygote (CG vs. GG and CC vs. CG), dominant, allele, and recessive models, respectively. Heterogeneity was detected in most genetic models, with subgroup analyses performed by ethnicity, genotyping method, and disease duration. The co-dominant model was determined to be the most appropriate genetic model.

CONCLUSIONS

Our findings suggested that polymorphism rs2910164 is not correlated with T2D susceptibility. However, the results should be interpreted with caution because of confounding factors.

Roles of Noncoding RNAs in Islet Biology

The discovery that most mammalian genome sequences are transcribed to ribonucleic acids (RNA) has revolutionized our understanding of the mechanisms governing key cellular processes and of the causes of human diseases, including diabetes mellitus. Pancreatic islet cells were found to contain thousands of noncoding RNAs (ncRNAs), including micro-RNAs (miRNAs), PIWI-associated RNAs, small nucleolar RNAs, tRNA-derived fragments, long non-coding RNAs, and circular RNAs. While the involvement of miRNAs in islet function and in the etiology of diabetes is now well documented, there is emerging evidence indicating that other classes of ncRNAs are also participating in different aspects of islet physiology. The aim of this article will be to provide a comprehensive and updated view of the studies carried out in human samples and rodent models over the past 15 years on the role of ncRNAs in the control of α- and β-cell development and function and to highlight the recent discoveries in the field. We not only describe the role of ncRNAs in the control of insulin and glucagon secretion but also address the contribution of these regulatory molecules in the proliferation and survival of islet cells under physiological and pathological conditions. It is now well established that most cells release part of their ncRNAs inside small extracellular vesicles, allowing the delivery of genetic material to neighboring or distantly located target cells. The role of these secreted RNAs in cell-to-cell communication between β-cells and other metabolic tissues as well as their potential use as diabetes biomarkers will be discussed. © 2020 American Physiological Society. Compr Physiol 10:893-932, 2020.

MicroRNA Networks in Pancreatic Islet Cells: Normal Function and Type 2 Diabetes

Impaired insulin secretion from the pancreatic β-cells is central in the pathogenesis of type 2 diabetes (T2D), and microRNAs (miRNAs) are fundamental regulatory factors in this process. Differential expression of miRNAs contributes to β-cell adaptation to compensate for increased insulin resistance, but deregulation of miRNA expression can also directly cause β-cell impairment during the development of T2D. miRNAs are small noncoding RNAs that posttranscriptionally reduce gene expression through translational inhibition or mRNA destabilization. The nature of miRNA targeting implies the presence of complex and large miRNA-mRNA regulatory networks in every cell, including the insulin-secreting β-cell. Here we exemplify one such network using our own data on differential miRNA expression in the islets of T2D Goto-Kakizaki rat model. Several biological processes are influenced by multiple miRNAs in the β-cell, but so far most studies have focused on dissecting the mechanism of action of individual miRNAs. In this Perspective we present key islet miRNA families involved in T2D pathogenesis including miR-200, miR-7, miR-184, miR-212/miR-132, and miR-130a/b/miR-152. Finally, we highlight four challenges and opportunities within islet miRNA research, ending with a discussion on how miRNAs can be utilized as therapeutic targets contributing to personalized T2D treatment strategies.

A Comprehensive Molecular Characterization of the Pancreatic Neuroendocrine Tumor Cell Lines BON-1 and QGP-1

Experimental models of neuroendocrine tumor disease are scarce, with only a few existing neuroendocrine tumor cell lines of pancreatic origin (panNET). Their molecular characterization has so far focused on the neuroendocrine phenotype and cancer-related mutations, while a transcription-based assessment of their developmental origin and malignant potential is lacking. In this study, we performed immunoblotting and qPCR analysis of neuroendocrine, epithelial, developmental endocrine-related genes as well as next-generation sequencing (NGS) analysis of microRNAs (miRs) on three panNET cell lines, BON-1, QGP-1, and NT-3. All three lines displayed a neuroendocrine and epithelial phenotype; however, while insulinoma-derived NT-3 cells preferentially expressed markers of mature functional pancreatic β-cells (i.e., INS, MAFA), both BON-1 and QGP-1 displayed high expression of genes associated with immature or non-functional β/δ-cells genes (i.e., NEUROG3), or pancreatic endocrine progenitors (i.e., FOXA2). NGS-based identification of miRs in BON-1 and QGP-1 cells revealed the presence of all six members of the miR-17–92 cluster, which have been implicated in β-cell function and differentiation, but also have roles in cancer being both oncogenic or tumor suppressive. Notably, both BON-1 and QGP-1 cells expressed several miRs known to be negatively associated with epithelial–mesenchymal transition, invasion or metastasis. Moreover, both cell lines failed to exhibit migratory activity in vitro. Taken together, NT-3 cells resemble mature functional β-cells, while both BON-1 and QGP-1 are more similar to immature/non-functional pancreatic β/δ-cells or pancreatic endocrine progenitors. Based on the recent identification of three transcriptional subtypes in panNETs, NT-3 cells resemble the “islet/insulinoma tumors” (IT) subtype, while BON-1 and QGP-1 cells were tentatively classified as “metastasis-like/primary” (MLP). Our results provide a comprehensive characterization of three panNET cell lines and demonstrate their relevance as neuroendocrine tumor models.

FAM3A plays crucial roles in controlling PDX1 and insulin expressions in pancreatic beta cells

So far, the mechanism that links mitochondrial dysfunction to PDX1 inhibition in the pathogenesis of pancreatic β cell dysfunction under diabetic condition remains largely unclear. This study determined the role of mitochondrial protein FAM3A in regulating PDX1 expression in pancreatic β cells using gain- and loss-of function methods in vitro and in vivo. Within pancreas, FAM3A is highly expressed in β, α, δ, and pp cells of islets. Islet FAM3A expression was correlated with insulin expression under physiological and diabetic conditions. Mice with specific knockout of FAM3A in islet β cells exhibited markedly blunted insulin secretion and glucose intolerance. FAM3A-deficient islets showed significant decrease in PDX1 expression, and insulin expression and secretion. FAM3A overexpression upregulated PDX1 and insulin expressions, and augmented insulin secretion in cultured islets and β cells. Mechanistically, FAM3A enhanced ATP production to elevate cellular Ca²⁺ level and promote insulin secretion. Furthermore, FAM3A-induced ATP release activated CaM to function as a co-activator of FOXA2, stimulating PDX1 gene transcription. In conclusion, FAM3A plays crucial roles in controlling PDX1 and insulin expressions in pancreatic β cells. Inhibition of FAM3A will trigger mitochondrial dysfunction to repress PDX1 and insulin expressions.

Transcriptome profiling of microRNAs associated with latent autoimmune diabetes in adults (LADA)

LADA (latent autoimmune diabetes in adults), a special subtype of type 1 diabetes, turns out to exhibit phenotypes mimicking the type 2 diabetes, which results in serious misdiagnosis issues. In order to better distinguish LADA from other diabetes subtypes, specific diagnostic and prognostic biomarkers of LADA are required. Circulating microRNAs (miRNAs) are recently shown to be promising biomarkers for disease diagnosis and subtyping. In this study, serum samples from LADA patients and type 2 diabetes patients were collected during the first diagnosis of diabetes and the miRNA transcriptomes of these patients and healthy individuals were profiled. Comparative analysis shows that the differentially expressed miRNAs between groups and their predicted target genes are enriched for several functions including immune regulation. Besides, a few miRNAs showing distinct expression pattern in LADA patients could discriminate LADA from type 2 diabetes, as validated by further qRT-PCR assay. In all, our study implies potential miRNA biomarkers which would be investigated in further clinical researches.

Pancreatic β-cell function is inhibited by miR-3666 in type 2 diabetes mellitus by targeting adiponectin

Type 2 diabetes mellitus (T2D) is a common endocrine and metabolic disorder, and poses threats to human health worldwide. Recently, microRNAs (miRNAs) have been suggested to play important roles in the pathophysiology of T2D. In this study, we explored the role of miR-3666 in T2D. miR-3666 was significantly down-regulated in the serum of T2D patients when compared to that of healthy volunteers, and miR-3666 expression level was negatively correlated with blood glucose levels of T2D patients. Overexpression of miR-3666 inhibited cell proliferation, reduced insulin secretion, and promoted cell apoptosis of pancreatic β-cell line (INS-1 cells). On the other hand, knockdown of miR-3666 had the opposite effects in INS-1 cells. The bio-informatics analysis using TargetScan revealed that adiponectin (ADIPOQ) was a downstream target of miR-3666, and the interaction between miR-3666 and ADIPOQ was validated by luciferase reporter assay. In addition, miR-3666 negatively regulated the mRNA and protein expression of ADIPOQ. Overexpression of ADIPOQ promoted insulin secretion after glucose stimulation, promoted cell proliferation, inhibited cell apoptosis, and partially abolished the effects of miR-3666 overexpression on insulin secretion, cell proliferation, and cell apoptosis of INS-1 cells. In conclusion, our results revealed that miR-3666 inhibited pancreatic cell proliferation, reduced insulin sensitivity, and promoted apoptosis by targeting ADIPOQ.

RNA interference-based therapy and its delivery systems

RNA interference (RNAi) is considered a highly specific approach for gene silencing and holds tremendous potential for treatment of various pathologic conditions such as cardiovascular diseases, viral infections, and cancer. Although gene silencing approaches such as RNAi are widely used in preclinical models, the clinical application of RNAi is challenging primarily because of the difficulty in achieving successful systemic delivery. Effective delivery systems are essential to enable the full therapeutic potential of RNAi. An ideal nanocarrier not only addresses the challenges of delivering naked siRNA/miRNA, including its chemically unstable features, extracellular and intracellular barriers, and innate immune stimulation, but also offers "smart" targeted delivery. Over the past decade, great efforts have been undertaken to develop RNAi delivery systems that overcome these obstacles. This review presents an update on current progress in the therapeutic application of RNAi with a focus on cancer therapy and strategies for optimizing delivery systems, such as lipid-based nanoparticles.

microRNA-690 regulates induced pluripotent stem cells (iPSCs) differentiation into insulin-producing cells by targeting Sox9

Background

The regulatory mechanism of insulin-producing cells (IPCs) differentiation from induced pluripotent stem cells (iPSCs) in vitro is very important in the phylogenetics of pancreatic islets, the molecular pathogenesis of diabetes, and the acquisition of high-quality pancreatic β-cells derived from stem cells for cell therapy.

Methods

miPSCs were induced for IPCs differentiation. miRNA microarray assays were performed by using total RNA from our iPCs-derived IPCs containing undifferentiated iPSCs and iPSCs-derived IPCSs at day 4, day 14, and day 21 during step 3 to screen the differentially expressed miRNAs (DEmiRNAs) related to IPCs differentiation, and putative target genes of DEmiRNAs were predicted by bioinformatics analysis. miR-690 was selected for further research, and MPCs were transfected by miR-690-agomir to confirm whether it was involved in the regulation of IPCs differentiation in iPSCs. Quantitative Real-Time PCR (qRT-PCR), Western blotting, and immunostaining assays were performed to examine the pancreatic function of IPCs at mRNA and protein level respectively. Flow cytometry and ELISA were performed to detect differentiation efficiency and insulin content and secretion from iPSCs-derived IPCs in response to stimulation at different concentration of glucose. The targeting of the 3′-untranslated region of Sox9 by miR-690 was examined by luciferase assay.

Results

We found that miR-690 was expressed dynamically during IPCs differentiation according to the miRNA array results and that overexpression of miR-690 significantly impaired the maturation and insulinogenesis of IPCs derived from iPSCs both in vitro and in vivo. Bioinformatic prediction and mechanistic analysis revealed that miR-690 plays a pivotal role during the differentiation of IPCs by directly targeting the transcription factor sex-determining region Y (SRY)-box9. Furthermore, downstream experiments indicated that miR-690 is likely to act as an inactivated regulator of the Wnt signaling pathway in this process.

Conclusions

We discovered a previously unknown interaction between miR-690 and sox9 but also revealed a new regulatory signaling pathway of the miR-690/Sox9 axis during iPSCs-induced IPCs differentiation.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1154-8) contains supplementary material, which is available to authorized users.

miR‑6835‑3p regulates the function of pancreatic islet cells by modulating the expression of AdipoR1

Effective drugs and strategies for treating type 2 diabetes mellitus (2‑DM) are urgently required. The aim of the present study was to elucidate the mechanism underlying microRNA (miR)‑6835‑3p regulation of adiponectin receptor 1 (AdipoR1) expression and the miR‑6835‑3p/AdipoR1 signaling pathway in pancreatic islet cells. In addition, the potential anti‑diabetes effect of miR‑6835‑3p on insulin secretion was investigated. Luciferase activity analysis was performed to evaluate how miR‑6835‑3p targets the 3'‑untranslated region of AdipoR1. The SU.86.86 and MIN‑6 cell lines were co‑cultured with or without miR‑6835‑3p inhibitors or mimics, and the insulin secretory functions of these cell lines were then determined. Luciferase reporter analysis revealed that AdipoR1 was a direct target of miR‑6835‑3p. In addition, miR‑6835‑3p overexpression suppressed the mRNA and protein expression levels of AdipoR1 in the SU.86.86 and MIN‑6 cell lines. Furthermore, miR‑6835‑3p exerted negative effects on insulin secretion in SU.86.86 and MIN‑6 cells, which were mediated by regulating AdipoR1 expression. AdipoR1 was a direct target of miR‑6835‑3p; therefore, inhibition of AdiopR1 expression may reduce insulin secretion and may be considered a key regulator of insulin secretion. The results of the present study suggested that targeting AdipoR1 with miR‑6835‑3p inhibitors may be a potential strategy for promoting glucose‑stimulated insulin secretion, and thereby, may be an effective treatment for type 2‑DM.

MicroRNA profiling of second trimester maternal plasma shows upregulation of miR-195-5p in patients with gestational diabetes

Gestational diabetes (GDM) is defined as glucose intolerance that presents during pregnancy. It increases the risk of developing diabetes later in life. Recent studies indicate the important role of microRNAs (miRNAs) in the pathogenesis of diabetes, including GDM. However, information on the plasma miRNA profile in GDM patients at the late second trimester, at which time the glucose metabolism disorder manifests, is scarce. This study aimed to determine the plasma miRNA expression profiles of the pregnant women with GDM and compare them to those of pregnant controls using the real-time PCR array method. The study involved 22 single-pregnancy women (mean age ± standard deviation of 29.9 ± 4.5 years old) who underwent a glucose tolerance test between 23 and 31 weeks of gestation. Of them, 13 were diagnosed with GDM. We identified 15 upregulated miRNAs in the GDM patients that were involved in 41 pathways. Among the top 10 associated pathways, fatty acid biosynthesis and fatty acid metabolism were targeted by the most, of the miRNAs investigated, with very low p values (p < 1e-325, false discovery rate corrected). MiR-195-5p, which targeted the highest number of genes important in metabolism, showed the highest fold upregulation. We conclude that increased miRNA expression, especially miR-195-5p, in plasma is characteristic of and causally related to the development of GDM.

Adiponectin receptor 1-mediated micro RNA-323-3p regulates functions of the MIN6 cell line via the AMP-activated protein kinase/sirtuin-1 pathway

Background

The development of an effective treatment for type 2 diabetes mellitus is urgently needed. This study aimed to investigate the role of micro RNA (miR)-323-3p in regulating the expression of adiponectin receptor 1 (AdipoR1), as well as the insulin secretion and cell function of pancreatic MIN6 β-cells.

Methods

MIN6 cells were treated with miR-323-3p mimics or inhibitors, and the effects on cell growth, proliferation, mitosis, and insulin secretion were studied. The expression levels of sirtuin-1 (SIRT-1) and AMP-activated protein kinase (AMPK) genes were also assessed.

Results

miR-323-3p directly targeted AdipoR1, and suppressed its expression at mRNA and protein levels. It also regulated the protein expression of SIRT-1 and AMPK, which are downstream target genes of the AdipoR1 signaling pathway. miR-323-3p suppressed cell growth, proliferation, mitosis, and insulin secretion of MIN6 cells.

Conclusions

miR-323-3p appears to be a crucial diabetes factor that mediates its functions by inhibiting the AdipoR1/AMPK/SIRT-1 signaling pathway. Our findings suggest that targeting AdipoR1 with inhibitors of miR-323-3p is a potential approach to improve the function of islet cells.

microRNA-200a-3p enhances mitochondrial elongation by targeting mitochondrial fission factor

Mitochondria play pivotal roles in the ATP production, apoptosis and generation of reactive oxygen species. Although dynamic regulation of mitochondria morphology is a critical step to maintain cellular homeostasis, the regulatory mechanisms are not yet fully elucidated. In this study, we identified miR-200a-3p as a novel regulator of mitochondrial dynamics by targeting mitochondrial fission factor (MFF). We demonstrated that the ectopic expression of miR-200a-3p enhanced mitochondrial elongation, mitochondrial ATP synthesis, mitochondrial membrane potential and oxygen consumption rate. These results indicate that miR-200a-3p positively regulates mitochondrial elongation by downregulating MFF expression.

Jiang Tang Xiao Ke Granule Play an Anti-diabetic Role in Diabetic Mice Pancreatic Tissue by Regulating the mRNAs and MicroRNAs Associated with PI3K-Akt Signaling Pathway

Purpose: To investigate the effect of JTXK granule on the expression pattern of miRNA in pancreatic tissue of KKAy diabetic mice, and to explore the molecular mechanism and pathways of JTXK granule in anti-diabetic effect.

Methods: We used high fat diet (HFD) to induce the KKAy diabetic mice and screened the differentially expressed miRNAs (DEMs) between JTXK-treated group (n = 6) and the diabetic group (n = 6) using MicroRNA (miRNA) Microarray. C57BL/6J mice were given a normal diet as the control group (n = 6). Subsequently, miRNA target gene prediction, GO and Pathway analysis were used to explore the function of DEMs. Finally, the mechanism of anti-diabetic effects of JTXK granule was tested by in vitro INS-1 pancreatic β-cell experiment.

Results: The blood glucose and body weight of JTXK-treated group was significantly lower compared with the model group. Moreover, a total of 45 miRNAs with significant differences were detected in the model group and the JTXK-treated group (P ≤ 0.05, Fold Change > 2). Further, miRNA-mRNA analysis showed that the differential expression of mmu-miR-192-5p, mmu-miR-291a-3p, mmu-miR-320-3p, mmu-miR-139-5p and mmu-miR-378a-3p are closely related to pancreatic histological changes. In addition, pathway analysis showed that the DEMs were closely related to PI3K-Akt Signaling Pathway. Furthermore, the levels of serine/threonine-protein kinase (Akt), phosphorylated Akt (p-Akt) and phosphorylated forkhead transcription factor O1 (p-Foxo1) in INS-1-FOXO1 overexpressing model cells were lower than those in normal group, while JTXK granules could increase the expression of Akt, p-Akt and p-Foxo1.

Conclusions: The results showed that JTXK granule could play an anti-diabetic role by regulating the mRNA and miRNAs associated with PI3K-Akt pathway in diabetic mice pancreatic tissue.

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.

miRNA Signatures of Insulin Resistance in Obesity

OBJECTIVE

Extracellular microRNAs (miRNAs) represent functional biomarkers for obesity and related disorders; this study investigated plasma miRNAs in insulin resistance phenotypes in obesity.

METHODS

One hundred seventy-five miRNAs were analyzed in females with obesity (insulin sensitivity, n = 11; insulin resistance, n = 19; type 2 diabetes, n = 15) and without obesity (n = 12). Correlations between miRNA level and clinical parameters and levels of 15 miRNAs in a murine obesity model were investigated.

RESULTS

One hundred six miRNAs were significantly (adjusted P ≤ 0.05) different between controls and at least one obesity phenotype, including miRNAs with the following attributes: previously reported roles in obesity and altered circulating levels (e.g., miR-122, miR-192); known roles in obesity but no reported changes in circulating levels (e.g., miR-378a); and no current reported role in, or association with, obesity (e.g., miR-28-5p, miR-374b, miR-32). The miRNAs in the latter group were found to be associated with extracellular vesicles. Forty-eight miRNAs showed significant correlations with clinical parameters; stepwise regression retained let-7b, miR-144-5p, miR-34a, and miR-532-5p in a model predictive of insulin resistance (R²  = 0.57, P = 7.5 × 10^-8 ). Both miR-378a and miR-122 were perturbed in metabolically relevant tissues in a murine model of obesity.

CONCLUSIONS

This study expands on the role of extracellular miRNAs in insulin-resistant phenotypes of obesity and identifies candidate miRNAs not previously associated with obesity.

Role of microRNAs in obesity and obesity-related diseases

In recent years, the link between regulatory microRNAs (miRNAs) and diseases has been the object of intensive research. miRNAs have emerged as key mediators of metabolic processes, playing crucial roles in maintaining/altering physiological processes, including energy balance and metabolic homeostasis. Altered miRNAs expression has been reported in association with obesity, both in animal and human studies. Dysregulation of miRNAs may affect the status and functions of different tissues and organs, including the adipose tissue, pancreas, liver, and muscle, possibly contributing to metabolic abnormalities associated with obesity and obesity-related diseases. More recently, the discovery of circulating miRNAs easily detectable in plasma and other body fluids has emphasized their potential as both endocrine signaling molecules and disease indicators. In this review, the status of current research on the role of miRNAs in obesity and related metabolic abnormalities is summarized and discussed.

Culturing and transcriptome profiling of progenitor-like colonies derived from adult mouse pancreas

Background

Transplantation of insulin-producing cells is considered an important diabetes therapy. Many research studies have shown that insulin-producing cells can be derived from the in-vitro cultured pancreatic colonies with self-renewal ability and multilineage potential. Even though these progenitor-like colonies have been prepared from adult pancreas cells, the efficient culture method is hardly established and regulation of the colonies is rarely known. We confirmed previously that single cells acquired from adult mouse pancreas could form cyst-like colonies in a 3D semi-solid system containing Matrigel and methylcellulose. These colonies could be passaged continuously without losing progenitor-like capacity. In the previous culturing system, however, conditioned medium from murine embryonic-stem-cell-derived pancreatic-like cells was used. This unregulated ingredient may reduce repeatability and affect following study. Thus, a new culturing system with certain components needs to be developed.

Methods

Single cell suspension was acquired from adult mouse pancreas and cultured in a Matrigel-based 3D system with epidermal growth factor, Nicotinamide, B27, and Noggin to form ring colonies. Serial-passage assay was performed to evaluate self-renewal ability. Real-time polymerase chain reaction and immunostaining were used to detect the expression of progenitor-related genes. A 2D differentiation method was used to testify the multilineage potency of the colonies. High-throughput sequencing (HTS) of the colonies was performed to profile the differentially expressed genes.

Results

We developed a 3D culturing system deprived of conditioned medium to propagate those colonies with high proliferative efficiency. HTS of the transcriptome of mRNAs, microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) showed differentially expressed genes compared to the whole pancreas (as control). In mRNAs, several surface marker genes were identified in the colonies. Moreover in noncoding RNAs, miR-21a, miR-31 and miR-155 were upregulated and miR-217, miR-802 and miR-375 were downregulated in colonies along with a number of other miRNAs and lncRNAs.

Conclusions

Our results offer an efficient culture system for pancreatic progenitor-like colonies and HTS of the colonies serves as a target resource for following study of in-vitro cultured pancreatic progenitors. These findings should also contribute to our understanding of the transcriptional regulation of these progenitor-like colonies and the mechanisms behind their functions.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0626-y) contains supplementary material, which is available to authorized users.

Comprehensive circular RNA profiling reveals the regulatory role of the circRNA-100338/miR-141-3p pathway in hepatitis B-related hepatocellular carcinoma

Circular RNAs (circRNAs) represent a class of endogenous noncoding RNAs that have recently been recognized as important regulators of gene expression and pathological networks. However, their transcriptional activities and functional mechanisms in cancer remain largely unknown. Here, we present results from a global circRNA expression and functional analysis of patients with hepatocellular carcinoma (HCC). Using a circRNA microarray, we identified 226 differentially expressed circRNAs, of which 189 were significantly upregulated and 37 were downregulated. High expression of circRNA_100338, one of the upregulated circRNAs in HCC, is closely correlated with a low cumulative survival rate and metastatic progression in HCC patients with hepatitis B. Furthermore, our in silico and experimental analyses identified miR-141-3p as a direct target of circRNA_100338. Thus, circRNA_100338 functions as an endogenous sponge for miR-141-3p in HCC. In addition, we identified the crucial antagonistic roles of circRNA_100338 and miR-141-3p in the regulation of invasive potential in liver cancer cells. Overall, the differential expression of multiple circRNAs in HCC tissues and their clinical significance in hepatitis B-related HCC patients as revealed by our study suggests that circRNA_100338 is a potentially valuable biomarker for HCC diagnosis and target for HCC therapeutics.