microRNA Family Research Articles

Insulin resistance, endothelial and adipose dysfunction and atherosclerosis

Diabetes mellitus is a multisystem group of disorders associated with insulin resistance, metabolic stress, endothelial and adipose dysfunction and accelerated atherosclerosis. As the different players leading to atherosclerosis are known, the pathogenesis and eventually targets for treatment can be identified. The purpose of this review is to update the newer aspects of pathogenic factors as well as newer putative biomarkers in atherosclerosis. Hyperglycemia causes beta cell dysfunction, which results in impaired insulin secretion, endoplasmic reticulum stress and overproduction of reactive oxygen species. Lipotoxicity, or the accumulation of increased amounts of lipids in non-adipose tissue is found in the insulin producing pancreatic beta cells impairing their function. Gluco-lipotoxicity leads to the production of inflammatory cytokines, which damage the vasculature. Endothelial dysfunction, which occurs due to all these insults can be studied by biochemical alterations and by non-invasive imaging techniques. In addition, epigenetic changes have been identified in the pathogenesis. More recent biomediators were identified to be involved in the process of atherogenesis including adiponectin, leptin, resistin, adropin, visfatin, hepatokines, bone morphogenetic protein, nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), families of micro RNAs, extracellular vesicles (exosomes, ectosomes) and a variety of environmental factors. In view of managing conventional risk factors has not prevented atherosclerotic complications, the better understanding the role of pro- and anti- atherogenic factors may allow the development of novel drugs to modify them.

MiR-26 suppresses adipocyte progenitor differentiation and fat production by targeting Fbxl19.

Fat storage in adult mammals is a highly regulated process that involves the mobilization of adipocyte progenitor cells (APCs) that differentiate to produce new adipocytes. Here we report a role for the broadly conserved miR-26 family of microRNAs (miR-26a-1, miR-26a-2, and miR-26b) as major regulators of APC differentiation and adipose tissue mass. Deletion of all miR-26-encoding loci in mice resulted in a dramatic expansion of adipose tissue in adult animals fed normal chow. Conversely, transgenic overexpression of miR-26a protected mice from high-fat diet-induced obesity. These effects were attributable to a cell-autonomous function of miR-26 as a potent inhibitor of APC differentiation. miR-26 blocks adipogenesis, at least in part, by repressing expression of Fbxl19, a conserved miR-26 target without a previously known role in adipocyte biology that encodes a component of SCF-type E3 ubiquitin ligase complexes. These findings have therefore revealed a novel pathway that plays a critical role in regulating adipose tissue formation in vivo and suggest new potential therapeutic targets for obesity and related disorders.

PELP1 is a novel oncogene in gastric tumorigenesis and negatively regulated by miR-15 family microRNAs.

Gastric cancer (GC) is one of the leading causes of cancer-related death in East Asia and some South American countries, but its mechanism has not been clarified clearly. Proline-, glutamic acid-, and leucine-rich protein-1 (PELP1), a co-regulatory molecule of estrogen receptor α (ER α), is up-regulated in series of cancers such as endometrial carcinoma, ovarian cancer, colorectal cancer, breast cancer, and non-small cell lung cancer. However, PELP1's role in GC is still obscure, and its aberrant expression in cancers also remains to be explained. Immunohistochemical staining and Real-time PCR were used to compare the expression level of PELP1 in GC tissues and adjacent tissues. Western blot was used to detect the expression of PELP1 in cell lines. Kaplan-meier analysis and chi-square test were applied to evaluate the potential of PELP1 to function as a cancer biomarker. RNA interference was used to inhibit PELP1 expression in GC cells, followed by detecting cell proliferation, apoptosis, migration and invasion. Luciferase assay was conducted to validate whether miR-15 family members can directly target PELP1. In this study, we validated that PELP1 was significantly up-regulated in GC samples and cell lines. It was also demonstrated that the up-regulation of PELP1 was associated with several clinicopathologic features such as tumor diameter (P< 0.001), serum CEA level (P= 0.034), and lymphatic metastasis (P= 0.0009) of GC patients, and its high expression was correlated with shorter disease-free survival and overall survival of the patients. Knockdown of PELP1 remarkably arrested the proliferationï¼ migration and invasion, while promoted apoptosis. We also confirmed that miR-15 family microRNAs, most of which were down-regulated and tumor suppressor in cancers, were posttranscriptional regulators of PELP1. In conclusion, we demonstrated that PELP1 was an oncogene of GC associated with patients' prognosis and miR-15 family members contributed to its aberrant expression in cancers.

MicroRNA-34a Regulates the Depression-like Behavior in Mice by Modulating the Expression of Target Genes in the Dorsal Raphè.

Chronic stress exposure is known to increase vulnerability to the expression of psychiatric disorders, such as depression. Clinical and preclinical evidences support the involvement of the microRNA-34 family in stress-related psychiatric conditions and in the regulation of stress responses. However, the mechanism and the multiple targets by which the microRNA-34 family can affect the stress response and stress-related behavioral alteration are not fully known. Here, with the aid of constitutive and conditional genetic strategy, we examined the role of microRNA-34 family in the expression of depression-like phenotype in mice induced by chronic stress exposure, and we identified their "in vivo" targets during the stressful challenge. We found that microRNA-34a, under chronic stress, is significantly up-regulated in the mouse raphe nuclei, where its recruitment is necessary to induce depression-like behavioral alterations and impact the function of the serotonergic system. Moreover, by next-generation RNA-seq of Ago-2-bound mRNAs, we identified genes that are targeted by microRNA-34a in response to chronic stress and that are likely to mediate its effects.

The microRNA-200 family acts as an oncogene in colorectal cancer by inhibiting the tumor suppressor RASSF2.

This study aimed to determine whether manipulation of the microRNA-200 (miR-200) family could influence colon adenocarcinoma cell behavior. The miR-200 family has a significant role in tumor suppression and functions as an oncogene. In vitro studies on gain and loss of function with small interfering RNA demonstrated that the miR-200 family could regulate RASSF2 expression. Knockdown of the miR-200 family in the HT-29 colon cancer cell line increased KRAS expression but decreased signaling in the MAPK/ERK signaling pathway through reduced ERK phosphorylation. Increased expression of the miR-200 family in the CCD-841 colon epithelium cell line increased KRAS expression and led to increased signaling in the MAPK/ERK signaling pathway but increased ERK phosphorylation. Functionally, knockdown of the miR-200 family led to decreased cell proliferation in the HT-29 cells; therefore, increased miR-200 family expression could increase cell proliferation in the CCD-841 cell line. The present study included a large paired miR array dataset (n=632), in which the miR-200 family was significantly found to be increased in colon cancer when compared with normal adjacent colon epithelium. In a miR-seq dataset (n=199), the study found that miR-200 family expression was increased in localized colon cancer compared with metastatic disease. Decreased expression was associated with poorer overall survival. The miR-200 family directly targeted RASSF2 and was inversely correlated with RASSF2 expression (n=199, all P<0.001). Despite the well-defined role of the miR-200 family in tumor suppression, the present findings demonstrated a novel function of the miR-200 family in tumor proliferation.

MicroRNA-34 Family Enhances Wound Inflammation by Targeting LGR4

Venous ulcers are the most common type of human chronic nonhealing wounds and are stalled in a constant and excessive inflammatory state. The molecular mechanisms underlying the chronic wound inflammation remain elusive. Moreover, little is known about the role of regulatory RNAs, such as microRNAs, in the pathogenesis of venous ulcers. We found that both microRNA (miR)-34a and miR-34c were upregulated in the wound-edge epidermal keratinocytes of venous ulcers compared with normal wounds or the skin. In keratinocytes, miR-34a and miR-34c promoted inflammatory chemokine and cytokine production. In wounds of wild-type mice, miR-34a-mimic treatment enhanced inflammation and delayed healing. To further explore how miR-34 functions, LGR4 was identified as a direct target mediating the proinflammatory function of miR-34a and miR-34c. Interestingly, impaired wound closure with enhanced inflammation was also observed in Lgr4 knockout mice. Mechanistically, the miR-34-LGR4 axis regulated GSK-3β-induced p65 serine 468 phosphorylation, changing the activity of the NF-κB signaling pathway. Collectively, the miR-34-LGR4 axis was shown to regulate keratinocyte inflammatory response, the deregulation of which may play a pathological role in venous ulcers.

Repressive Gene Regulation Synchronizes Development with Cellular Metabolism

Metabolic conditions affect the developmental tempo of animals. Developmental gene regulatory networks (GRNs) must therefore synchronize their dynamics with a variable timescale. We find that layered repression of genes couples GRN output with variable metabolism. When repressors of transcription or mRNA and protein stability are lost, fewer errors in Drosophila development occur when metabolism is lowered. We demonstrate the universality of this phenomenon by eliminating the entire microRNA family of repressors and find that development to maturity can be largely rescued when metabolism is reduced. Using a mathematical model that replicates GRN dynamics, we find that lowering metabolism suppresses the emergence of developmental errors by curtailing the influence of auxiliary repressors on GRN output. We experimentally show that gene expression dynamics are less affected by loss of repressors when metabolism is reduced. Thus, layered repression provides robustness through error suppression and may provide an evolutionary route to a shorter reproductive cycle.

Integrated analyses of microRNA-29 family and the related combination biomarkers demonstrate their widespread influence on risk, recurrence, metastasis and survival outcome in colorectal cancer

BackgroundEmerging evidence has revealed miR-29 family as promising biomarkers for colorectal cancer (CRC), but their biomarker potential and molecular mechanisms remain poorly understood.MethodsWe performed a comprehensive meta-analysis to evaluate the biomarker performance of individual miR-29 and the related miRNA combination biomarkers. Meanwhile, we conducted an integrative bioinformatics analysis to unfold the underlying biological function of miR-29 and their relationship with CRC.ResultsUsing miR-29 expression to diagnose CRC produced 0.82 area under the curve, 70% sensitivity and 81% specificity while the combination biomarkers based on miR-29 enhanced the diagnostic power with an AUC of 0.86, a sensitivity of 78% and a specificity of 91%. For the prognosis evaluation, patients with higher expression of miR-29 had better survival outcome (pooled HR 0.78; 95% CI 0.56–1.07). In addition, miR-29 has also been identified as potential biomarker for predicting recurrence and metastasis in CRC. Then the genes regulated by the miR-29 family were retrieved and found closely associated with the molecular pathogenesis of CRC according to the gene ontology and pathway analysis. Furthermore, hub nodes and significant modules were identified from the protein–protein interaction network constructed with miR-29 family targets, which were also confirmed highly involved in the establishment and development of CRC.ConclusionsCurrent evidences suggest miR-29 family may become promising biomarkers for risk, recurrence, metastasis and survival outcome of CRC. Meanwhile our data highlight the potential clinical use of miRNA combination biomarkers. Nevertheless, further prospective studies are warranted before the application of the useful biomarkers in the clinical.

Correction: Trans-splicing of the C. elegans let-7 primary transcript developmentally regulates let-7 microRNA biogenesis and let-7 family microRNA activity (doi: 10.1242/dev.172031).

There was an error published in [Development (2019) 146, dev172031 ([doi:10.1242/dev.172031][2])][2]. In Table S3 in the supplementary material, the genotype for strain VT3903 was incorrect. Corrected: maEx267 [rol-6(su1006); unc-119+, plet-7::let-7 locus without mature let-7 sequence]; let-7(

INCREASED EXPRESSION OF THE NERVE GROWTH FACTOR (NGF) IN PULMONARY ARTERY IS ACCOMPANIED BY CHANGES OF PARTICULAR MICRORNAS LEVELS IN MONOCROTALINE-INDUCED PULMONARY HYPERTENSION

Objective: NGF is a member of the neurotrophin family, whose role has been described in the development and persistence of pulmonary hypertension (PH). Let-7 family is a group of microRNAs that targets NGF and downregulates its expression. On the other hand, microRNA miR-21, has been shown to support NGF signalling, and its expression is increased after NGF stimulation in neuronal cells. Furthermore, miR-21 was reported to contribute to proliferation and migration of lung vascular smooth muscle cells and to decrease BMPR-II expression. In this study, we examined the role of these microRNAs in regulation of NGF expression in pulmonary artery and lungs and, consequently, in the development of experimental monocrotaline-induced PH. Design and method: Male Wistar rats were injected either with monocrotaline (s.c. 60 mg/kg, MCT group) or with vehicle (CON group). Four weeks after MCT treatment, vital functions and right ventricular pressure of rats were measured. Expression of let-7 family, miR-21 and NGF was determined by qRT-PCR in rat pulmonary artery and whole lungs. Results: After MCT administration, we observed decreased oxygen saturation, increased right ventricular pressure and right ventricular hypertrophy (P < 0.05 vs CON). NGF gene expression was significantly increased in pulmonary artery (+106%, P < 0.05 vs CON). In the let-7 microRNA family, expression of two members, namely let-7 g and let-7i was significantly decreased (−31% and −34% respectively, P < 0.05 vs CON), whereas expression of miR-21 was significantly increased (+37%, P < 0.05 vs CON). In lung tissue, we did not note any change in NGF gene expression, together with no significant changes in expression of let-7 family. However, there was a significant increase in miR-21 expression (+92%, P < 0.05 vs CON). Conclusions: The decreased expression of let-7 g and let-7i microRNAs is in line with the increase in NGF expression in pulmonary artery. Additionally, increased miR-21 expression could further enhance NGF signalling. Therefore, we conclude that the let-7 – NGF – miR-21 axis could be a significant contributor to pulmonary vascular pathophysiology in MCT-induced PH.

Variables Associated with a Urinary MicroRNAs Excretion Profile Indicative of Renal Fibrosis in Fabry Disease Patients.

Introduction In advanced Fabry nephropathy stages, enzyme replacement theraphy (ERT) efficacy decreases, due to its impossibility to reverse renal fibrosis. Therefore, the finding of early kidney fibrosis biomarkers in affected patients is of interest. During renal fibrosis miR-21, miR-192 and miR-433 (fibrosis promotors) are activated by transforming growth factor-β (TGF-β), and miR-29 and miR-200 family (fibrosis supressors) are inhibited by TGF-β. The aim of this study is to analyze the probability that Fabry disease (FD) patients with some clinical variables can present an urinary microRNAs excretion profile indicative of renal fibrosis through a logistic regression analysis. Results A population of 34 participants was included: 24 FD patients and 10 controls. 16/24 (66.66%) FD patients presented microRNAs urinary excretion profile indicative of renal fibrosis. This profile was observed by decrease of fibrosis suppresors miR-29 and miR-200 and not by increase of fibrosis promotors miR-21, miR192, and miR-433. Hypohidrosis, angiokeratomas, neuropathic pain, hearing loss, cardiac involvement, male gender, reduced αGalA activity, and renin-angiotensin-aldosterone system inhibitors treatment are associated with the appearance of amicroRNAs urinary excretion profile indicative of renal fibrosis. A probable beneficial effect on urinary microRNAs excretion profile was observed in patients receiving ERT with agalsidase beta. The correlation between parameters of renal function with each family of microRNAs was studied. The only association with statistical significance was found between miR-21 and urine albumin-creatinine ratio (p =0.021). Conclusions A probable microRNAs regulation not mediated by TGF-β should be considered or TGF-β has a different effect in FD than in other nephropathies on microRNAs regulation. Typical clinical manifestations of classic FD are associated with appearance of urinary microRNAs profile indicative of renal fibrosis. FD patients express renal fibrosis biomarkers in urine prior to onset of pathological albuminuria. A direct correlation between urinary miR-21 and degree of albuminuria was observed.

C/EBP\u03b2-LIP induces cancer-type metabolic reprogramming by regulating the let-7/LIN28B circuit in mice

The transcription factors LAP1, LAP2 and LIP are derived from the Cebpb-mRNA through the use of alternative start codons. High LIP expression has been associated with human cancer and increased cancer incidence in mice. However, how LIP contributes to cellular transformation is poorly understood. Here we present that LIP induces aerobic glycolysis and mitochondrial respiration reminiscent of cancer metabolism. We show that LIP-induced metabolic programming is dependent on the RNA-binding protein LIN28B, a translational regulator of glycolytic and mitochondrial enzymes with known oncogenic function. LIP activates LIN28B through repression of the let-7 microRNA family that targets the Lin28b-mRNA. Transgenic mice overexpressing LIP have reduced levels of let-7 and increased LIN28B expression, which is associated with metabolic reprogramming as shown in primary bone marrow cells, and with hyperplasia in the skin. This study establishes LIP as an inducer of cancer-type metabolic reprogramming and as a regulator of the let-7/LIN28B regulatory circuit.

The gut microbiota regulates white adipose tissue inflammation and obesity via a family of microRNAs.

The gut microbiota is a key environmental determinant of mammalian metabolism. Regulation of white adipose tissue (WAT) by the gut microbiota is a process critical to maintaining metabolic fitness, and gut dysbiosis can contribute to the development of obesity and insulin resistance (IR). However, how the gut microbiota regulates WAT function remains largely unknown. Here, we show that tryptophan-derived metabolites produced by the gut microbiota controlled the expression of the miR-181 family in white adipocytes in mice to regulate energy expenditure and insulin sensitivity. Moreover, dysregulation of the gut microbiota-miR-181 axis was required for the development of obesity, IR, and WAT inflammation in mice. Our results indicate that regulation of miR-181 in WAT by gut microbiota-derived metabolites is a central mechanism by which host metabolism is tuned in response to dietary and environmental changes. As we also found that MIR-181 expression in WAT and the plasma abundance of tryptophan-derived metabolites were dysregulated in a cohort of obese human children, the MIR-181 family may represent a potential therapeutic target to modulate WAT function in the context of obesity.

MiR-17-92 and miR-106b-25 clusters regulate beta cell mitotic checkpoint and insulin secretion in mice.

Adult beta cells in the pancreas are the sole source of insulin in the body. Beta cell loss or increased demand for insulin impose metabolic challenges because adult beta cells are generally quiescent and infrequently re-enter the cell division cycle. The aim of this study is to test the hypothesis that a family of proto-oncogene microRNAs that includes miR-17-92 and miR-106b-25 clusters regulates beta cell proliferation or function in the adult endocrine pancreas. To elucidate the role of miR-17-92 and miR-106b-25 clusters in beta cells, we used a conditional miR-17-92/miR-106b-25 knockout mouse model. We employed metabolic assays in vivo and ex vivo, together with advanced microscopy of pancreatic sections, bioinformatics, mass spectrometry and next generation sequencing, to examine potential targets of miR-17-92/miR-106b-25, by which they might regulate beta cell proliferation and function. We demonstrate that miR-17-92/miR-106b-25 regulate the adult beta cell mitotic checkpoint and that miR-17-92/miR-106b-25 deficiency results in reduction in beta cell mass in vivo. Furthermore, we reveal a critical role for miR-17-92/miR-106b-25 in glucose homeostasis and in controlling insulin secretion. We identify protein kinase A as a new relevant molecular pathway downstream of miR-17-92/miR-106b-25 in control of adult beta cell division and glucose homeostasis. The study contributes to the understanding of proto-oncogene miRNAs in the normal, untransformed endocrine pancreas and illustrates new genetic means for regulation of beta cell mitosis and function by non-coding RNAs. Sequencing data that support the findings of this study have been deposited in GEO with the accession code GSE126516.

Dual mechanisms of posttranscriptional regulation of Tet2 by Let-7 microRNA in macrophages

Tet methylcytosine dioxygenase 2 (Tet2) is an epigenetic regulator that removes methyl groups from deoxycytosine residues in DNA. Tet2-deficient murine macrophages show increased lipopolysaccharide (LPS)-induced and spontaneous inflammation at least partially because Tet2 acts to restrain interleukin (IL)-1β and IL-6 expression in induced cells. MicroRNAs have emerged as critical regulatory noncoding RNAs that tune immune cell responses to physiological perturbations and play roles in pathological conditions in macrophages. To determine if a microRNA played any role in Tet2 activity, we examined the interrelationship of Tet2 action and the let-7 microRNA family, utilizing several let-7 microRNA engineered murine models. We first showed that Tet2, but not Tet3, is a direct target of the let-7a-1/let-7d/let-7f-1 (let-7adf) microRNAs in macrophages. We found that overexpression or deletion of the let-7adf gene cluster causes altered IL-6 induction both in tissue culture cells induced by LPS treatment in vitro as well as in a Salmonella infection mouse model in vivo. Mechanistically, let-7adf promotes IL-6 by directly repressing Tet2 levels and indirectly by enhancing a Tet2 suppressor, the key TCA cycle metabolite, succinate. We found that Let-7adf promotes succinate accumulation by regulating the Lin28a/Sdha axis. We thereby identify two pathways of let-7 control of Tet2 and, in turn, of the key inflammatory cytokine, IL-6, thus characterizing a regulatory pathway in which a microRNA acts as a feedback inhibitor of inflammatory processes.

Conserved miR396b-GRF Regulation Is Involved in Abiotic Stress Responses in Pitaya (Hylocereus polyrhizus).

MicroRNA396 (miR396) is a conserved microRNA family that targets growth-regulating factors (GRFs), which play significant roles in plant growth and stress responses. Available evidence justifies the idea that miR396-targeted GRFs have important functions in many plant species; however, no genome-wide analysis of the pitaya (Hylocereus polyrhizus) miR396 gene has yet been reported. Further, its biological functions remain elusive. To uncover the regulatory roles of miR396 and its targets, the hairpin sequence of pitaya miR396b and the open reading frame (ORF) of its target, HpGRF6, were isolated from pitaya. Phylogenetic analysis showed that the precursor miR396b (MIR396b) gene of plants might be clustered into three major groups, and, generally, a more recent evolutionary relationship in the intra-family has been demonstrated. The sequence analysis indicated that the binding site of hpo-miR396b in HpGRF6 is located at the conserved motif which codes the conserved “RSRKPVE” amino acid in the Trp–Arg–Cys (WRC) region. In addition, degradome sequencing analysis confirmed that four GRFs (GRF1, c56908.graph_c0; GRF4, c52862.graph_c0; GRF6, c39378.graph_c0 and GRF9, c54658.graph_c0) are hpo-miR396b targets that are regulated by specific cleavage at the binding site between the 10th and 11th nucleotides from the 5′ terminus of hpo-miR396b. Furthermore, quantitative real-time polymerase chain reaction (qRT-PCR) analysis showed that hpo-miR396b is down-regulated when confronted with drought stress (15% polyethylene glycol, PEG), and its expression fluctuates under other abiotic stresses, i.e., low temperature (4 ± 1 °C), high temperature (42 ± 1 °C), NaCl (100 mM), and abscisic acid (ABA; 0.38 mM). Conversely, the expression of HpGRF6 showed the opposite trend to exposure to these abiotic stresses. Taken together, hpo-miR396b plays a regulatory role in the control of HpGRF6, which might influence the abiotic stress response of pitaya. This is the first documentation of this role in pitaya and improves the understanding of the molecular mechanisms underlying the tolerance to drought stress in this fruit.

The relationship of lncRNA NR2F1 and breast cancer angiogenesis via IL-8/lncRNA NR2F1/miR-200s/IL-8 loop.

e12573 Background: Angiogenesis is key for metastasis and predicts a poor prognosis in breast cancer. Among the pro-angiogenic factors, interleukin-8 (IL-8) could be secreted by tumor cells mediated by microRNA-200 family (miR-200s). Long non-coding RNA (LncRNA), was reported to absorb microRNA to play multiple roles in various diseases including breast cancer. Our preliminary results recognized lncRNA NR2F1 through Agilent Human LncRNA array from breast cancer cells overexpressing IL-8. However, the relationship between LncRNA NR2F1 and breast cancer angiogenesis remains unknown. Methods: Breast cancer cell migration, invasion, proliferation and angiogenesis were assessed by Transwell, CCK8, tube formation, and wound healing assays. The expression of LncRNA NR2F1, miR-200s and IL-8 were detected by qPCR, Western blotting and ELISA. Breast cancer metastasis and angiogenesis in vivo were measured in a zebrafish model. Results: We found that the basal expression of lncRNA NR2F1 is higher in breast cancer cell lines than it in normal cells. In vitro, lncRNA NR2F1 induced breast cancer migration, invasion, and proliferation. Meanwhile, lncRNA NR2F1 promoted human umbilical vascular endothelial cell (HUVEC) proliferation, tube formation, and migration both via breast cancer conditioned medium and via direct HUVEC transfection. In the zebrafish model, lncRNA NR2F1 promoted breast cancer cell metastasis and neo-angiogenesis. Further study disclosed that lncRNA NR2F1 downregulated the expression of miR-200s, which in turn upregulated the expression of IL-8 in breast cancer cells. Conclusions: Our findings suggest that LncRNA NR2F1, as a potential promoter of breast cancer, may induce breast cancer angiogenesis through IL-8/lncRNA NR2F1/miR-200s/IL-8 loop.

Pheromones and Nutritional Signals Regulate the Developmental Reliance on let-7 Family MicroRNAs in C. elegans

Adverse environmental conditions can affect rates ofanimal developmental progression and lead to temporary developmental quiescence (diapause), exemplified by the dauer larva stage of the nematode Caenorhabditis elegans (C.elegans). Remarkably, patterns of cell division and temporal cell-fate progression in C.elegans larvae are not affected by changes in developmental trajectory. However, the underlying physiological and gene regulatory mechanisms that ensure robust developmental patterning despite substantial plasticity in developmental progression are largely unknown. Here, we report thatdiapause-inducing pheromones correct heterochronic developmental cell lineage defects caused by insufficient expression of let-7 family microRNAs in C.elegans. Moreover, two conserved endocrine signaling pathways, DAF-7/TGF-β and DAF-2/Insulin, that confer on the larva diapause and non-diapause alternative developmental trajectories interact with the nuclear hormone receptor, DAF-12, to initiate and regulate a rewiring of the genetic circuitry controlling temporal cell fates. This rewiring includes engagement of certain heterochronic genes, lin-46, lin-4, and nhl-2, that are previously associated with an altered genetic program in post-diapause animals, in combination with a novel ligand-independent DAF-12 activity, to downregulate the critical let-7 family target Hunchback-like-1 (HBL-1). Our results show how pheromone or endocrine signaling pathways can coordinately regulate both developmental progression and cell-fate transitions in C.elegans larvae under stress so that the developmental schedule of cell fates remains unaffected by changes in developmental trajectory.

QKI, a miR-200 target gene, suppresses epithelial-to-mesenchymal transition and tumor growth.

The microRNA-200 (miR-200) family plays a major role in specifying epithelial phenotype by preventing expression of the transcription repressors ZEB1 and ZEB2, which are well-known regulators of the epithelial-to-mesenchymal transition (EMT) in epithelial tumors including oral squamous cell carcinoma (OSCC). Here, we elucidated whether miR-200 family members control RNA-binding protein quaking (QKI), a newly identified tumor suppressor that is regulated during EMT. We predicted that miR-200a and miR-200b could recognize QKI 3'-UTR by analyzing TargetScan and The Cancer Genome Atlas head and neck squamous cell carcinoma (HNSCC) dataset. Forced expression of miR-200b/a/429 inhibited expression of ZEB1/2 and decreased cell migration in OSCC cell lines CAL27 and HSC3. QKI expression was also suppressed by miR-200 overexpression, and the 3'-UTR of QKI mRNA was directly targeted by miR-200 in luciferase reporter assays. Interestingly, shRNA-mediated knockdown of QKI led to pronounced EMT and protumor effects in both in vitro and in vivo studies of OSCC. Furthermore, high expression of QKI protein is associated with favorable prognosis in surgically resected HNSCC and lung adenocarcinoma. In conclusion, QKI increases during EMT and is targeted by miR-200; while, it suppresses EMT and tumorigenesis. We suggest that QKI and miR-200 form a negative feedback loop to maintain homeostatic responses to EMT-inducing signals.

A therapeutic approach towards microRNA29 family in vascular diabetic complications: A boon or curse?

Diabetes Mellitus (DM) is one of the major metabolic disorders and its severity leads to death. Enhancement in hyperglycaemic conditions of DM gives rise to endothelial impairment in small and large blood vessels contributing towards microvascular and macrovascular complications respectively. The pathogenesis of diabetic complications is associated with interruption of various signal transduction pathways due to epigenetic modifications such as aberrant histone modifications, DNA methylation and expression of miRNAs along with the long non-coding RNAs (lncRNAs). Amongst these epigenetic alterations, modulated expressions of miRNAs confer to apoptosis and endothelial dysfunction of organs that gives rise to vascular complications. In this review, we principally focussed on physiological role of miR29 family in DM and have discussed crosstalk between miR29 family and numerous genes involved in signal transduction pathways of Diabetic vascular complications. Incidences of diabetic retinopathy exploiting the role of miR29 in regulation of EMT process, differential expression patterns of miR29 and promising therapeutic role of miR29 have been discussed. We have summarised the therapeutic role of miR29 in podocyte impairment and how miR29 regulates the expressions of profibrotic, inflammatory and ECM encoding genes in renal fibrosis under diabetic conditions. We have also highlighted impact of miR29 expression patterns in cardiac angiopathy, cardiomyocyte's apoptosis and cardiac fibrosis. Additionally, we have also presented the contradictory actions of miR29 family in amelioration as well as in enhancement of diabetic complications.