The miR-200-Zeb1 axis regulates key aspects of β-cell function and survival in vivo

Relevance of Circulating microRNA, and their Association with Islet Cell Autoantibodies in Type 1 Diabetes Pathogenesis

BACKGROUND

AIMS/HYPOTHESIS

The role of microRNAs (miRNAs) in the pathogenesis and progression of type 1 diabetes (T1D) has been described, but data remain scarce and conflicting.

OBJECTIVES

To evaluate the potential biological involvement of miRNA expression in the immune response and beta cell function in T1D.

METHODS

We screened 10 serum miRNAs from 142 subjects divided into three groups: healthy individuals (control group; n = 52) and patients at different stages of T1D progression, from the initial immunological manifestation, presenting islet cell autoantibodies (AbP group; n = 39), to partial and severe beta cell damage in T1D (recent T1D group; n = 51).

RESULTS

Three miRNAs (miR-200c-3p, miR-301a-3p, and miR-382-5p) were highly expressed in the AbP and/or recent T1D groups compared to the control group. Furthermore, in the AbP group, miR-301a-3p and miR-382-5p were positively correlated with insulin autoantibody levels and miR-382-5p was negatively correlated with C-peptide levels. In the recent T1D group, miR-200c-3p expression was positively correlated with IA-2A levels. Enrichment analysis of differentially expressed miRNAs showed their involvement in immune response, inflammatory pathways, proliferation/survival/apoptosis mechanisms, bacterial and viral infection, and insulin resistance.

CONCLUSION

Our data indicated that miR-200c-3p, miR-301a-3p, and miR-382-5p might be involved in T1D pathogenesis. Proliferative, metabolic, and immune responses were main pathways associated with serum miRNA target genes.

MiRNA-200a and miRNA-200b expression, and vitamin-D level: Prognostic significance in obese non-diabetic and obese type 2 diabetes mellitus individuals

BACKGROUND

Obesity and type 2 diabetes mellitus (T2DM) are frequent co-occurring disorders that affect regular metabolic functions. Obesity has also been linked to an increased risk of developing diabetes. Obesity and diabetes are on the rise, increasing healthcare costs and raising mortality rates. Research has revealed that the expression profile of microRNAs (miRNAs) changes as diabetes progresses. Furthermore, vitamin D may have an anti-obesity effect and inverse association with body weight and body mass index (BMI). Low vitamin D levels do not solely cause obesity, which could be a factor in the etiology of T2DM.

AIM

To evaluate miRNA-200a and miRNA-200b expression, and vitamin-D levels in obese and obese T2DM individuals.

METHODS

This study included 210 participants, of which, 82 were obese (BMI > 30 kg/m2) without T2DM, 28 were obese with T2DM, and 100 were healthy controls. BMI was evaluated and both fasting and postprandial blood glucose were used to confirm T2DM. Exosomal miRNA-200a and miRNA-200b expression were analyzed using real-time PCR using Taqman probes, and vitamin-D levels were evaluated using an electrochemiluminescence-based immunoassay technique. All data analyses were performed using SPSS 20.0 and GraphPad Prism 5 software.

RESULTS

Overall, a 2.20- and 4.40-fold increase in miRNA-200a and miRNA-200b expression was observed among participants compared to healthy controls. MiRNA-200a and miRNA-200b expression among obese participants increased 2.40-fold and 3.93-fold, respectively, while in obese T2DM participants these values were 2.67-fold, and 5.78-fold, respectively, and these differences were found to be statistically significant (P = 0.02) (P < 0.0001). Obese participants showed a vitamin D level of 34.27 ng/mL, while in obese-T2DM participants vitamin D level was 22.21 ng/mL (P < 0.0001). Vitamin D was negatively correlated with miRNA-200a (r = -0.22, P = 0.01) and miRNA-200b (r = -0.19, P = 0.04). MiRNA-200a sensitivity was 75%, and specificity was 57%, with a cutoff value of 2.07-fold. MiRNA-200b sensitivity was 75%, and specificity was 71% with a cutoff value of 4.12-fold, suggesting that miRNA-200a and miRNA-200b with an increased expression of 2.07- and 4.12-fold could be predictive indicators for the risk of diabetes in obese participants.

CONCLUSION

MiRNA-200a and miRNA-200b were higher in diabetic obese participants vs non-diabetic obese participants, and insufficient vitamin D levels in obese T2DM participants may be involved in poor clinical outcome.

Targeting β-Cell Plasticity: A Promising Approach for Diabetes Treatment

The β-cells within the pancreas play a pivotal role in insulin production and secretion, responding to fluctuations in blood glucose levels. However, factors like obesity, dietary habits, and prolonged insulin resistance can compromise β-cell function, contributing to the development of Type 2 Diabetes (T2D). A critical aspect of this dysfunction involves β-cell dedifferentiation and transdifferentiation, wherein these cells lose their specialized characteristics and adopt different identities, notably transitioning towards progenitor or other pancreatic cell types like α-cells. This process significantly contributes to β-cell malfunction and the progression of T2D, often surpassing the impact of outright β-cell loss. Alterations in the expressions of specific genes and transcription factors unique to β-cells, along with epigenetic modifications and environmental factors such as inflammation, oxidative stress, and mitochondrial dysfunction, underpin the occurrence of β-cell dedifferentiation and the onset of T2D. Recent research underscores the potential therapeutic value for targeting β-cell dedifferentiation to manage T2D effectively. In this review, we aim to dissect the intricate mechanisms governing β-cell dedifferentiation and explore the therapeutic avenues stemming from these insights.

A microrheological examination of insulin-secreting β-cells in healthy and diabetic-like conditions

Pancreatic β-cells regulate glucose homeostasis through glucose-stimulated insulin secretion, which is hindered in type-2 diabetes. Transport of the insulin vesicles is expected to be affected by changes in the viscoelastic and transport properties of the cytoplasm. These are evaluated in situ through particle-tracking measurements using a rat insulinoma β-cell line. The use of inert probes assists in decoupling the material properties of the cytoplasm from the active transport through cellular processes. The effect of glucose-stimulated insulin secretion is examined, and the subsequent remodeling of the cytoskeleton, at constant effects of cell activity, is shown to result in reduced mobility of the tracer particles. Induction of diabetic-like conditions is identified to alter the mean-squared displacement of the passive particles in the cytoplasm and diminish its reaction to glucose stimulation.

ETV5 Silencing Produces Mesenchymal to Epithelial Transition in INS-1 (832/13) Cell Line

ETV5 has been described to be involved in the epithelial to mesenchymal transition (EMT) mainly in cancer. It is known that EMT provokes cytoskeleton remodeling, improving cellular migratory, and invasive capabilities. Moreover, overexpression of ETV5 has been correlated to cancer development and this gene has been implicated in cell proliferation. However, little is known about the downregulation of ETV5 expression in a pancreatic cell line and the inverse mesenchymal to epithelial transition (MET). Therefore, we studied the implications of ETV5 silencing over the phenotype of the insulinoma INS-1 (832/13) cell line and described the MET by partial ETV5 silencing in the INS-1 (832/13) cell line. The downregulation of ETV5 expression was obtained by using ETV5 siRNA in the insulinoma rat cell line, INS-1 (832/13). Then, ETV5 knockdown provoked a MET phenotype observed by crystal violet staining and verified by immunohistochemistry against E-cadherin. Wound healing assay showed no migration, and F-actin stain revealed rearrangement of actin microfilaments. In addition, TGFβ1 and TGFβ3 were downregulated in the absence of ETV5. ETV5 silencing induces epithelial phenotype by downregulating TGFβ1 and TGFβ3 in INS-1 (832/13) cell line.

Unveiling the mechanisms and challenges of cancer drug resistance

Cancer treatment faces many hurdles and resistance is one among them. Anti-cancer treatment strategies are evolving due to innate and acquired resistance capacity, governed by genetic, epigenetic, proteomic, metabolic, or microenvironmental cues that ultimately enable selected cancer cells to survive and progress under unfavorable conditions. Although the mechanism of drug resistance is being widely studied to generate new target-based drugs with better potency than existing ones. However, due to the broader flexibility in acquired drug resistance, advanced therapeutic options with better efficacy need to be explored. Combination therapy is an alternative with a better success rate though the risk of amplified side effects is commonplace. Moreover, recent groundbreaking precision immune therapy is one of the ways to overcome drug resistance and has revolutionized anticancer therapy to a greater extent with the only limitation of being individual-specific and needs further attention. This review will focus on the challenges and strategies opted by cancer cells to withstand the current therapies at the molecular level and also highlights the emerging therapeutic options -like immunological, and stem cell-based options that may prove to have better potential to challenge the existing problem of therapy resistance. Video Abstract.

A Review of micro RNAs changes in T2DM in animals and humans

Type 2 diabetes mellitus (T2DM) and its associated complications have become a crucial public health concern in the world. According to the literature, chronic inflammation and the progression of T2DM have a close relationship. Accumulated evidence suggests that inflammation enhances the insulin secretion lost by islets of Langerhans and the resistance of target tissues to insulin action, which are two critical features in T2DM development. Based on recently highlighted research that plasma concentration of inflammatory mediators such as tumor necrosis factor α and interleukin-6 are elevated in insulin-resistant and T2DM, and it raises novel question marks about the processes causing inflammation in both situations. Over the past few decades, microRNAs (miRNAs), a class of short, noncoding RNA molecules, have been discovered to be involved in the regulation of inflammation, insulin resistance, and T2DM pathology. These noncoding RNAs are specifically comprised of RNA-induced silencing complexes and regulate the expression of specific protein-coding genes through various mechanisms. There is extending evidence that describes the expression profile of a special class of miRNA molecules altered during T2DM development. These modifications can be observed as potential biomarkers for the diagnosis of T2DM and related diseases. In this review study, after reviewing the possible mechanisms involved in T2DM pathophysiology, we update recent information on the miRNA roles in T2DM, inflammation, and insulin resistance.

Visual analytics identifies key miRNAs for differentiating peripancreatic paraganglioma and pancreatic neuroendocrine tumors

Introduction

Paragangliomas (PGL), a type of neuroendocrine tumor, pose a significant diagnostic challenge due to their potential for unpredictable locations and asymptomatic presentation. Misdiagnosis of peripancreatic PGLs, particularly as pancreatic neuroendocrine tumors (PANNETs), is a pressing issue as it can negatively impact both pre- and post-treatment decision-making. The aim of our study was to identify microRNA markers for the reliable differential diagnosis of peripancreatic PGLs and PANNETs, addressing a crucial unmet need in the field and advancing the standard of care for these patients.

Methods

Morphing projections tool was used to analyze miRNA data from PGL and PANNET tumors present in the TCGA database. The findings were validated using two additional databases: GSE29742 and GSE73367.

Results

Our research uncovered substantial differences in the miRNA expression profiles of PGL and PANNET, leading to the identification of 6 key miRNAs (miR-10b-3p, miR-10b-5p, and the miRNA families miR-200c/141 and miR-194/192) that can effectively differentiate between the two types of tumors.

Discussion

These miRNA levels hold potential as biomarkers for improved diagnosis, offering a solution to the diagnostic challenge posed by these tumors and potentially improving the standard of care for patients.

Aging Impairs Adaptive Unfolded Protein Response and Drives Beta Cell Dedifferentiation in Humans

CONTEXT

Diabetes is an age-related disease; however, the mechanism underlying senescent beta cell failure is still unknown.

OBJECTIVE

The present study was designed to investigate whether and how the differentiated state was altered in senescent human beta cells by excluding the effects of impaired glucose tolerance.

METHODS

We calculated the percentage of hormone-negative/chromogranin A-positive endocrine cells and evaluated the expressions of forkhead box O1 (FoxO1) and Urocortin 3 (UCN3) in islets from 31 nondiabetic individuals, divided into young (<40 years), middle-aged (40-60 years) and elderly (>60 years) groups. We also assessed adaptive unfolded protein response markers glucose-regulated protein 94 (GRP94), and spliced X-box binding protein 1 (XBP1s) in senescent beta cells and their possible contributions to maintaining beta cell identity and differentiation state.

RESULTS

We found an almost 2-fold increase in the proportion of dedifferentiated cells in elderly and middle-aged groups compared with the young group (3.1 ± 1.0% and 3.0 ± 0.9% vs 1.7 ± 0.5%, P < .001). This was accompanied by inactivation of FoxO1 and loss of UCN3 expression in senescent human beta cells. In addition, we demonstrated that the expression levels of adaptive unfolded protein response (UPR) components GRP94 and XBP1s declined with age. In vitro data showed knockdown GRP94 in Min6-triggered cells to dedifferentiate and acquire progenitor features, while restored GRP94 levels in H2O2-induced senescent Min6 cells rescued beta cell identity.

CONCLUSION

Our finding highlights that the failure to establish proper adaptive UPR in senescent human beta cells shifts their differentiated states, possibly representing a crucial step in the pathogenesis of age-related beta cell failure.

Zeb1 sustains hematopoietic stem cell functions by suppressing mitofusin-2-mediated mitochondrial fusion

Metabolic status is essential in maintaining normal functions of hematopoietic stem cells (HSCs). However, how the dynamic of the mitochondrion, as a central organelle in metabolism, is molecularly regulated to orchestrate metabolism and HSC stemness remains to be elucidated. Here, we focus on the role of Zeb1, a well-characterized epithelial-to-mesenchymal transition (EMT) inducer which has been demonstrated to confer stem-cell-like characteristics in multiple cancer types in stemness regulation of HSCs. Using a Zeb1-tdTomato reporter mouse model, we find that Zeb1⁺Lin^-Sca-1⁺c-Kit⁺ cells (Zeb1⁺-LSKs) represent a subset of functional long-term HSCs. Zeb1⁺LSKs exhibit a reduced reactive oxygen species (ROS) level, low mitochondrial mass, low mitochondrial membrane potential (MMP), and particularly small, round fragmented mitochondria. Of note, ectopic expression of Zeb1 leads to a fragmented mitochondrial morphology with a low mitochondrial metabolic status in EML cells. In addition, Zeb1-knockout (Zeb1-KO) LSKs from fetal liver display an exhausted stem-cell activity. Zeb1 deficiency results in elongated and tubulated mitochondria with increased mitochondrial mass, elevated MMP, and higher ROS production. Mechanistically, Zeb1 acts as a transcriptional suppressor on the key mitochondrial-fusion protein Mitofusin-2 (encoded by Mfn2). We highlight an important role of Zeb1 in the regulation of mitochondrial morphology in HSC and the metabolic control of HSC stemness by repressing Mfn2-mediated mitochondrial fusion.

elk1/miR-462-731 Feedback Loop Regulates Macrophages Polarization and Phagocytosis in Grass Carp (Ctenopharyngodon idella)

MicroRNA clusters are microRNAs (miRNAs) that are distributed in close proximity on chromosomes. In this study, we report a miRNA cluster identified from grass carp (Ctenopharyngodon idella), miR-462-731, which plays a positive role in host antibacterial immunity. The expression of miR-462-731 was disrupted after infection by Aeromonas hydrophila. Transcription factor ETS transcription factor ELK1 was identified to bind to the promoter of the miR-462-731 cluster and suppress its expression. In addition, miR-731 negatively regulates the expression of elk1, forms an elk1/miR-462-731 double negative feedback loop. In addition, we found that miR-731 directly targets ezrin a (ezra), participates in inducing PI3K/AKT signaling in macrophage, to induce macrophage polarization to the M1 phenotype with stronger phagocytosis. Our results demonstrate a novel elk1/miR-462-731 feedback loop. The data deepen our understanding of the relationship between macrophage polarization and phagocytosis in teleost fish.

Human Islet MicroRNA-200c Is Elevated in Type 2 Diabetes and Targets the Transcription Factor ETV5 to Reduce Insulin Secretion

MicroRNAs (miRNAs) are part of deregulated insulin secretion in type 2 diabetes (T2D) development. Rodent models have suggested miR-200c to be involved, but the role and potential as therapeutic target of this miRNA in human islets are not clear. Here we report increased expression of miR-200c in islets from T2D as compared with nondiabetic (ND) donors and display results showing reduced glucose-stimulated insulin secretion in EndoC-βH1 cells overexpressing miR-200c. We identify transcription factor ETV5 as the top rank target of miR-200c in human islets using TargetScan in combination with Pearson correlation analysis of miR-200c and mRNA expression data from the same human donors. Among other targets were JAZF1, as earlier shown in miR-200 knockout mice. Accordingly, linear model analysis of ETV5 and JAZF1 gene expression showed reduced expression of both genes in islets from human T2D donors. Western blot analysis confirmed the reduced expression of ETV5 on the protein level in EndoC-βH1 cells overexpressing miR-200c, and luciferase assay validated ETV5 as a direct target of miR-200c. Finally, LNA knockdown of miR-200c increased glucose-stimulated insulin secretion in islets from T2D donors approximately threefold. Our data reveal a vital role of the miR-200c-ETV5 axis in β-cell dysfunction and pathophysiology of T2D.