miR-296-3p, miR-298-5p and their downstream networks are causally involved in the higher resistance of mammalian pancreatic α cells to cytokine-induced apoptosis as compared to β cells

Characterization of MicroRNA expression profiles in the ovarian tissue of goats during the sexual maturity period

BACKGROUND

The ovary is an important reproductive organ in mammals, and its development directly affects the sexual maturity and reproductive capacity of individuals. MicroRNAs (miRNAs) are recognized as regulators of reproductive physiological processes in various animals and have been shown to regulate ovarian development through typical targeting and translational repression. However, little is known about the regulatory role of miRNAs in ovarian tissue development during sexual maturity in goats. To comprehensively profile the different physiological stages of sexual maturation in goats, we performed small-RNA sequencing of ovarian tissue samples collected at four specific time points (1 day after birth (D1), 2 months old (M2), 4 months old (M4), and 6 months old (M6)). In addition, we used ELISAs to measure serum levels of reproductive hormones to study their temporal changes.

RESULTS

The results showed that serum levels of gonadotropin-releasing hormone, follicle-stimulating hormone, luteinizing hormone, oestradiol, progesterone, oxytocin, and prolactin were lower in goats at the D1 stage than at the other three developmental stages (P < 0.05). The secretion patterns of these seven hormones show a similar trend, with hormone levels reaching their peaks at 4 months of age. A total of 667 miRNAs were detected in 20 libraries, and 254 differentially expressed miRNAs and 3 groups of miRNA clusters that had unique expression patterns were identified (|log2-fold change|> 1, FDR < 0.05) in the 6 comparison groups. RT‒qPCR was employed to confirm that the expression pattern of the 15 selected miRNAs was consistent with the Illumina sequencing results. Gene ontology analyses revealed significant enrichment of GO terms such as cell proliferation regulation, epithelial cell development, and amino acid transport, as well as important signaling pathways including the MAPK signaling pathway, the PI3K-Akt signaling pathway, and the oestrogen signaling pathway. Further miRNA‒mRNA regulation network analysis revealed that 8 differentially expressed miRNAs (chi-miR-1343, chi-miR-328-3p, chi-miR-877-3p, chi-miR-296-3p, chi-miR-128-5p, chi-miR-331-3p, chi-miR-342-5p and chi-miR-34a) have important regulatory roles in ovarian cell proliferation, hormone secretion and metabolism-related biological processes.

CONCLUSIONS

Overall, our study investigated the changes in serum hormone and miRNA levels in the ovaries. These data provide a valuable resource for understanding the molecular regulatory mechanisms of miRNAs in ovarian tissue during the sexual maturity period in goats.

Glimepiride Compared to Liraglutide Increases Plasma Levels of miR-206, miR-182-5p, and miR-766-3p in Type 2 Diabetes Mellitus: A Randomized Controlled Trial

BACKGRUOUND

Diabetes is a chronic disease with several long-term complications. Several glucose-lowering drugs are used to treat type 2 diabetes mellitus (T2DM), e.g., glimepiride and liraglutide, in which both having different modes of action. Circulating microRNAs (miRNAs) are suggested as potential biomarkers that are associated with the disease development and the effects of the treatment. In the current study we evaluated the effect of glimepiride, liraglutide on the expression of the circulating miRNAs.

METHODS

The present study is a post hoc trial from a previously randomized control trial comparing liraglutide versus glimepiride both in combination with metformin in subjects with T2DM, and subclinical heart failure. miRNAs were determined in the subjects' serum samples with next generation sequencing. Expression patterns of the circulating miRNAs were analyzed using bioinformatic univariate and multivariate analyses (clinical trial registration: NCT01425580).

RESULTS

Univariate analyses show that treatment with glimepiride altered expression of three miRNAs in patient serum, miR-206, miR-182-5p, and miR-766-3p. Both miR-182-5p and miR-766-3p were also picked up among the top contributing miRNAs with penalized regularised logistic regressions (Lasso). The highest-ranked miRNAs with respect to Lasso coefficients were miR-3960, miR-31-5p, miR-3613-3p, and miR-378a-3p. Liraglutide treatment did not significantly influence levels of circulating miRNAs.

CONCLUSION

Present study indicates that glucose-lowering drugs differently affect the expression of circulating miRNAs in serum in individuals with T2DM. More studies are required to investigate possible mechanisms by which glimepiride is affecting the expression of circulating miRNAs.

circSMARCA5 Is an Upstream Regulator of the Expression of miR-126-3p, miR-515-5p, and Their mRNA Targets, Insulin-like Growth Factor Binding Protein 2 (IGFBP2) and NRAS Proto-Oncogene, GTPase (NRAS) in Glioblastoma

The involvement of non-coding RNAs (ncRNAs) in glioblastoma multiforme (GBM) pathogenesis and progression has been ascertained but their cross-talk within GBM cells remains elusive. We previously demonstrated the role of circSMARCA5 as a tumor suppressor (TS) in GBM. In this paper, we explore the involvement of circSMARCA5 in the control of microRNA (miRNA) expression in GBM. By using TaqMan^® low-density arrays, the expression of 748 miRNAs was assayed in U87MG overexpressing circSMARCA5. Differentially expressed (DE) miRNAs were validated through single TaqMan^® assays in: (i) U87MG overexpressing circSMARCA5; (ii) four additional GBM cell lines (A172; CAS-1; SNB-19; U251MG); (iii) thirty-eight GBM biopsies; (iv) twenty biopsies of unaffected brain parenchyma (UC). Validated targets of DE miRNAs were selected from the databases TarBase and miRTarbase, and the literature; their expression was inferred from the GBM TCGA dataset. Expression was assayed in U87MG overexpressing circSMARCA5, GBM cell lines, and biopsies through real-time PCR. TS miRNAs 126-3p and 515-5p were upregulated following circSMARCA5 overexpression in U87MG and their expression was positively correlated with that of circSMARCA5 (r-values = 0.49 and 0.50, p-values = 9 × 10^-5 and 7 × 10^-5, respectively) in GBM biopsies. Among targets, IGFBP2 (target of miR-126-3p) and NRAS (target of miR-515-5p) mRNAs were positively correlated (r-value = 0.46, p-value = 0.00027), while their expression was negatively correlated with that of circSMARCA5 (r-values = -0.58 and -0.30, p-values = 0 and 0.019, respectively), miR-126-3p (r-value = -0.36, p-value = 0.0066), and miR-515-5p (r-value = -0.34, p-value = 0.010), respectively. Our data identified a new GBM subnetwork controlled by circSMARCA5, which regulates downstream miRNAs 126-3p and 515-5p, and their mRNA targets IGFBP2 and NRAS.

Alteration of LncRNA expression in mice placentae after frozen embryo transfer is associated with increased fetal weight

The birthweight after frozen embryo transfer (FET) was significantly higher compared with fresh embryo transfer (fresh ET), while the mechanism remains unclear. In this study, we transferred vitrified-warmed or fresh mice blastocysts into pseudopregnant recipients (n = 11 each group) produced by natural mating to avoid the influence of superovulation. The fetal weight, placental weight, placental efficiency and placental architecture were studied at E18.5. Placental RNA-Seq analysis was used to identify candidate different lncRNAs and mRNAs between the FET group and the fresh ET group. We found that the fetal weight was increased in the FET group, with increased placental efficiency and the proportion of placental function related labyrinth zone area. 554 lncRNAs and 1012 mRNAs were differentially expressed. KEGG and GO enrichment analyses showed these differentially expressed lncRNAs and their targeted mRNAs might be related to placental morphogenesis. Furthermore, the most differentially expressed 15 lncRNAs and 15 mRNAs were validated by qRT-PCR, we found the LncRNA embryonic stem cells expressed 1 (Lncenc1) was significantly decreased, and Gjb5, which played an important role in labyrinth zone development, was increased. Gjb5 protein increase was further confirmed by Western blot. Lncenc1 and Gjb5 had 48 predicted co-targeted miRNAs, while the correlation analysis of Lncenc1 and Gjb5 mRNA showed a significant inverse correlation. The results showed that FET treatment might enhance the placental function to increase mouse fetal weight via the network diagram of Lncenc1-miRNA-Gjb5.

Deciphering the link between Diabetes mellitus and SARS-CoV-2 infection through differential targeting of microRNAs in the human pancreas

PURPOSE

Coronavirus Disease 2019 (COVID-19) severity and Diabetes mellitus affect each other bidirectionally. However, the cause of severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) infection on the incidence of diabetes is unclear. In the SARS-CoV-2-infected cells, host microRNAs (miRNAs) may target the native gene transcripts as well as the viral genomic and subgenomic RNAs. Here, we investigated the role of miRNAs in linking Diabetes to SARS-CoV-2 infection in the human pancreas.

METHODS

Differential gene expression and disease enrichment analyses were performed on an RNA-Seq dataset of human embryonic stem cell-derived (hESC) mock-infected and SARS-CoV-2-infected pancreatic organoids to obtain the dysregulated Diabetes-associated genes. The miRNA target prediction for the Diabetes-associated gene transcripts and the SARS-CoV-2 RNAs has been made to determine the common miRNAs targeting them. Minimum Free Energy (MFE) analysis was done to identify the miRNAs, preferably targeting SARS-CoV-2 RNAs over the Diabetes-associated gene transcripts.

RESULTS

The gene expression and disease enrichment analyses of the RNA-Seq data have revealed five biomarker genes, i.e., CP, SOCS3, AGT, PSMB8 and CFB that are associated with Diabetes and get significantly upregulated in the pancreas following SARS-CoV-2-infection. Four miRNAs, i.e., hsa-miR-298, hsa-miR-3925-5p, hsa-miR-4691-3p and hsa-miR-5196-5p, showed preferential targeting of the SARS-CoV-2 genome over the cell's Diabetes-associated messenger RNAs (mRNAs) in the human pancreas.

CONCLUSION

Our study proposes that the differential targeting of the Diabetes-associated host genes by the miRNAs may lead to diabetic complications or new-onset Diabetes that can worsen the condition of COVID-19 patients.

Competing endogenous RNA network mediated by circ_3205 in SARS-CoV-2 infected cells

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is a new member of the Betacoronaviridae family, responsible for the recent pandemic outbreak of COVID-19. To start exploring the molecular events that follow host cell infection, we queried VirusCircBase and identified a circular RNA (circRNA) predicted to be synthesized by SARS-CoV-2, circ_3205, which we used to probe: (i) a training cohort comprised of two pools of cells from three nasopharyngeal swabs of SARS-CoV-2 infected (positive) or uninfected (negative, UCs) individuals; (ii) a validation cohort made up of 12 positive and 3 negative samples. The expression of circRNAs, miRNAs and miRNA targets was assayed through real-time PCR. CircRNA-miRNA interactions were predicted by TarpMiR, Analysis of Common Targets for circular RNAs (ACT), and STarMir tools. Enrichment of the biological processes and the list of predicted miRNA targets were retrieved from DIANA miRPath v3.0. Our results showed that the predicted SARS-CoV-2 circ_3205 was expressed only in positive samples and its amount positively correlated with that of SARS-CoV-2 Spike (S) mRNA and the viral load (r values = 0.80952 and 0.84867, Spearman's correlation test, respectively). Human (hsa) miR-298 was predicted to interact with circ_3205 by all three predictive tools. KCNMB4 and PRKCE were predicted as hsa-miR-298 targets. Interestingly, the function of both is correlated with blood coagulation and immune response. KCNMB4 and PRKCE mRNAs were upregulated in positive samples as compared to UCs (6 and 8.1-fold, p values = 0.049 and 0.02, Student's t test, respectively) and their expression positively correlated with that of circ_3205 (r values = 0.6 and 0.25, Spearman's correlation test, respectively). We propose that our results convincingly suggest that circ_3205 is a circRNA synthesized by SARS-CoV-2 upon host cell infection and that it may behave as a competitive endogenous RNA (ceRNA), sponging hsa-miR-298 and contributing to the upregulation of KCNMB4 and PRKCE mRNAs.

Aloperine inhibits colorectal cancer cell proliferation and metastasis progress via regulating miR-296-5p/STAT3 axis

Anti-tumorous effect of Aloperine (ALO) has been previously found. This study examined the role and the underlying mechanism of ALO in colorectal cancer (CRC). CRC cells were processed by different concentrations of ALO, and subsequently the cell proliferation was detected by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and miR-296-5p expression was determined by quantitative real-time polymerase chain reaction (qRT-PCR). Moreover, the target gene of miR-296-5p was predicted by TargetScan and confirmed by dual-luciferase reporter assay. The expressions of signal transducer and activator of transcription 3 (STAT3), apoptosis-related proteins and epithelial-mesenchymal transition (EMT)-related markers were measured by Western blot. Clone formation assay, flow cytometry, wound-healing and Transwell assays were respectively employed to detect cell proliferation, apoptosis, migration and invasion. ALO inhibited CRC cell proliferation in a dose-dependent manner. MiR-296-5p was low-expressed in CRC tissues and cells, and ALO promoted miR-296-5p expression. STAT3 was targeted by miR-296-5p. Up-regulation of miR-296-5p and ALO treatment both suppressed STAT3 expression, inhibited CRC cell proliferation, migration, invasion as well as the expressions of Bcl-2 and N-cadherin, but promoted apoptosis and expressions of Bax and E-cadherin, which were all reversed by overexpressed STAT3. ALO inhibited CRC cell proliferation, metastasis and EMT but promoted apoptosis via regulating miR-296-5p/STAT3 axis.

MiR-9-3p regulates the biological functions and drug resistance of gemcitabine-treated breast cancer cells and affects tumor growth through targeting MTDH

This study explored the role of MTDH in regulating the sensitivity of breast cancer cell lines to gemcitabine (Gem) and the potential miRNAs targeting MTDH. The expression of MTDH in cancer tissues and cells was detected by immunohistochemical staining or qRT-PCR. The target genes for MTDH were predicted by bioinformatics and further confirmed by dual-luciferase reporter assay and qRT-PCR. Cancer cells were transfected with siMTDH, MTDH, miR-9-3p inhibitor, or mimics and treated by Gem, then CCK-8, colony formation assay, tube formation assay, flow cytometry, wound healing assay, and Transwell were performed to explore the effects of MTDH, miR-9-3p, and Gem on cancer cell growth, apoptosis, migration, and invasion. Expressions of VEGF, p53, cleaved caspase-3, MMP-2, MMP-9, E-Cadherin, N-Cadherin, and Vimentin were determined by Western blot. MTDH was high-expressed in cancer tissues and cells, and the cells with high-expressed MTDH were less sensitive to Gem, while silencing MTDH expression significantly promoted the effect of Gem on inducing apoptosis, inhibiting cell migration, invasion, and growth, and on regulating protein expressions of cancer cells. Moreover, miR-9-3p had a targeted binding relationship with MTDH, and overexpressed miR-9-3p greatly promoted the toxic effects of Gem on cancer cells and expressions of apoptosis-related proteins, whereas overexpressed MTDH partially reversed such effects of overexpressed miR-9-3p. The study proved that miR-9-3p regulates biological functions, drug resistance, and the growth of Gem-treated breast cancer cells through targeting MTDH.

Identification of differentially expressed miRNAs in serum extracellular vesicles (EVs) of Kazakh sheep at early pregnancy

MiRNAs-containing extracellular vesicles (EVs) possess the unique function of mediating intercellular communication and participating in many biological processes such as post-transcriptional gene regulation of embryo implantation and placental development. In the present study, Illumina small-RNA sequencing was used to identify differentially expressed (DE) miRNAs in serum EVs of pregnant (P) and non-pregnant (NP) Kazakh sheep at Day 17 from mating. The specifically and differentially expressed miRNAs at early pregnancy in sheep were verified by using RT-PCR. The target genes of DE miRNAs were predicted by bioinformatics software, and the functional and pathway enrichment analysis was performed on Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) terms. A total of 562 miRNAs (210 novel miRNAs) were identified by sequencing, of which 57 miRNAs were differentially expressed, 49 were up-regulated, 8 were down-regulated and 22 novel miRNAs were specifically expressed in the pregnant sheep. Eight highly expressed known miRNA (miR-378-3p, miR-320-3p, miR-22-3p, let-7b, miR-423-3p, miR-221, miR-296-3p, miR-147-3p) in pregnant group were down-regulated in the control group. miRNAs-containing pregnancy-related terms and regulatory pathways regulation were enriched using both GO and KEGG analyses. Moreover, we also envisioned a miRNA-mRNA interaction network to understand the function of miRNAs involved in the early pregnancy serum regulatory network. The results of RT-PCR verification confirmed the reliability of small-RNA sequencing. Among them, miR-22-3p and miR-378-3p were significantly differentially expressed (DE) between pregnant sheep and non-pregnant group (p <  0.01). The site at which oar-miR-22-3p binds MAPK3 was determined with a dual-luciferase system. This is the first integrated analysis of the expression profiles of EV-miRNAs and their targets during early pregnancy in ewes. These data identify key miRNAs that influence the implantation of sheep in the early stage of pregnancy, and provide theoretical basis for further molecular regulatory mechanisms research.

Intracerebral hemorrhage alters circular RNA expression profiles in the rat brain

Circular RNAs (circRNAs), formed from pre-messenger RNAs by back-splicing, are a novel class of evolutionarily-conserved endogenous non-coding RNAs. While circRNAs are involved in various diseases, the role of circRNAs in intracerebral hemorrhage (ICH) remains unknown. In the present study, we performed high-throughput sequencing to profile the expression of circRNAs in the rat brain at 24 and 48 hours after ICH onset, and utilized bioinformatics methods to make predictions about the function of dysregulated circRNAs. Compared with the sham group, 346 and 389 circRNAs changed significantly (|log2 (fold change)| > 1 and P < 0.05) at 24 and 48 hours after ICH, respectively. Bioinformatics analyses indicated that parent genes of dysregulated circRNAs were involved in biological processes, cellular component, and molecular function following ICH, and that they were enriched in the dopaminergic synapses, glutamatergic synapses, endocytosis, regulation of actin cytoskeleton, the mitogen-activated protein kinase signaling pathway, and the retrograde endocannabinoid signaling pathway. Enrichment analyses of target mRNAs showed that these mRNAs were enriched in synaptic plasticity, ion channel activity, and pathways including the phospholipase D signaling and the cGMP-PKG signaling. Our study indicates that the expression profile of circRNAs changes significantly after ICH in rat brains, and suggests that circRNAs may be crucial for the pathophysiological process following ICH.

Seasonal effects on miRNA and transcriptomic profile of oocytes and follicular cells in buffalo (Bubalus bubalis)

Season clearly influences oocyte competence in buffalo (Bubalus bubalis); however, changes in the oocyte molecular status in relation to season are poorly understood. This study characterizes the microRNA (miRNA) and transcriptomic profiles of oocytes (OOs) and corresponding follicular cells (FCs) from buffalo ovaries collected in the breeding (BS) and non-breeding (NBS) seasons. In the BS, cleavage and blastocyst rates are significantly higher compared to NBS. Thirteen miRNAs and two mRNAs showed differential expression (DE) in FCs between BS and NBS. DE-miRNAs target gene analysis uncovered pathways associated with transforming growth factor β (TGFβ) and circadian clock photoperiod. Oocytes cluster in function of season for their miRNA content, showing 13 DE-miRNAs between BS and NBS. Between the two seasons, 22 differentially expressed genes were also observed. Gene Ontology (GO) analysis of miRNA target genes and differentially expressed genes (DEGs) in OOs highlights pathways related to triglyceride and sterol biosynthesis and storage. Co-expression analysis of miRNAs and mRNAs revealed a positive correlation between miR-296-3p and genes related to metabolism and hormone regulation. In conclusion, season significantly affects female fertility in buffalo and impacts on oocyte transcriptomic of genes related to folliculogenesis and acquisition of oocyte competence.

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.

Identification of microRNAs involved in NOD-dependent induction of pro-inflammatory genes in pulmonary endothelial cells

The nucleotide-binding oligomerization domain-containing proteins (NOD) 1 and 2 are mammalian cytosolic pattern recognition receptors sensing bacterial peptidoglycan fragments in order to initiate cytokine expression and pathogen host defense. Since endothelial cells are relevant cells for pathogen recognition at the blood/tissue interface, we here analyzed the role of NOD1- and NOD2-dependently expressed microRNAs (miRNAs, miR) for cytokine regulation in murine pulmonary endothelial cells. The induction of inflammatory cytokines in response to NOD1 and NOD2 was confirmed by increased expression of tumour necrosis factor (Tnf)-α and interleukin (Il)-6. MiRNA expression profiling revealed NOD1- and NOD2-dependently regulated miRNA candidates, of which miR-147-3p, miR-200a-3p, and miR-298-5p were subsequently validated in pulmonary endothelial cells isolated from Nod1/2-deficient mice. Analysis of the two down-regulated candidates miR-147-3p and miR-298-5p revealed predicted binding sites in the 3' untranslated region (UTR) of the murine Tnf-α and Il-6 mRNA. Consequently, transfection of endothelial cells with miRNA mimics decreased Tnf-α and Il-6 mRNA levels. Finally, a novel direct interaction of miR-298-5p with the 3' UTR of the Il-6 mRNA was uncovered by luciferase reporter assays. We here identified a mechanism of miRNA-down-regulation by NOD stimulation thereby enabling the induction of inflammatory gene expression in endothelial cells.

miR-132-3p is a positive regulator of alpha-cell mass and is downregulated in obese hyperglycemic mice

Objective

Diabetes is a complex disease implicating several organs and cell types. Within the islets, dysregulation occurs in both alpha- and beta-cells, leading to defects of insulin secretion and increased glucagon secretion. Dysregulation of alpha-cells is associated with transcriptome changes. We hypothesized that microRNAs (miRNAs) which are negative regulators of mRNA stability and translation could be involved in alpha-cell alterations or adaptations during type 2 diabetes.

Methods

miRNA microarray analyses were performed on pure alpha- and beta-cells from high-fat diet fed obese hyperglycemic mice and low-fat diet fed controls. Then, the most regulated miRNA was overexpressed or inhibited in primary culture of mouse and human alpha-cells to determine its molecular and functional impact.

Results

16 miRNAs were significantly regulated in alpha-cells of obese hyperglycemic mice and 28 in beta-cells. miR-132-3p had the strongest regulation level in alpha-cells, where it was downregulated, while we observed an opposite upregulation in beta-cells. In vitro experiments showed that miR-132-3p, which is inversely regulated by somatostatin and cAMP, is a positive modulator of alpha-cell proliferation and implicated in their resistance to apoptosis. These effects are associated with the regulation of a series of genes, including proliferation and stress markers Mki67 and Bbc3 in mouse and human alpha-cells, potentially involved in miR-132-3p functions.

Conclusions

Downregulation of miR-132-3p in alpha-cells of obese diabetic mice may constitute a compensatory mechanism contributing to keep glucagon-producing cell number constant in diabetes.

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Alpha- and beta-cells present specific microRNA signatures.

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16 microRNAs are significantly regulated in alpha-cells of obese hyperglycemic mice.

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miR-132-3p is downregulated in alpha-cells of obese hyperglycemic mice.

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miR-132-3p stimulates alpha-cells proliferation and resistance to apoptosis.

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miR-132-3p is regulated by somatostatin in alpha-cells.

PARP-14 Promotes Survival of Mammalian α but Not β Pancreatic Cells Following Cytokine Treatment

PARP-14 (poly-ADP Ribose Polymerase-14), a member of the PARP family, belongs to the group of Bal proteins (B Aggressive Lymphoma). PARP-14 has recently appeared to be involved in the transduction pathway mediated by JNKs (c Jun N terminal Kinases), among which JNK2 promotes cancer cell survival. Several pharmacological PARP inhibitors are currently used as antitumor agents, even though they have also proved to be effective in many inflammatory diseases. Cytokine release from immune system cells characterizes many autoimmune inflammatory disorders, including type I diabetes, in which the inflammatory state causes β cell loss. Nevertheless, growing evidence supports a concomitant implication of glucagon secreting α cells in type I diabetes progression. Here, we provide evidence on the activation of a survival pathway, mediated by PARP-14, in pancreatic α cells, following treatment of αTC1.6 glucagonoma and βTC1 insulinoma cell lines with a cytokine cocktail: interleukin 1 beta (IL-1β), interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α). Through qPCR, western blot and confocal analysis, we demonstrated higher expression levels of PARP-14 in αTC1.6 cells with respect to βTC1 cells under inflammatory stimuli. By cytofluorimetric and caspase-3 assays, we showed the higher resistance of α cells compared to β cells to apoptosis induced by cytokines. Furthermore, the ability of PJ-34 to modulate the expression of the proteins involved in the survival pathway suggests a protective role of PARP-14. These data shed light on a poorly characterized function of PARP-14 in αTC1.6 cells in inflammatory contexts, widening the potential pharmacological applications of PARP inhibitors.

Exercise Training-Induced Changes in MicroRNAs: Beneficial Regulatory Effects in Hypertension, Type 2 Diabetes, and Obesity

MicroRNAs are small non-coding RNAs that regulate gene expression post-transcriptionally. They are involved in the regulation of physiological processes, such as adaptation to physical exercise, and also in disease settings, such as systemic arterial hypertension (SAH), type 2 diabetes mellitus (T2D), and obesity. In SAH, microRNAs play a significant role in the regulation of key signaling pathways that lead to the hyperactivation of the renin-angiotensin-aldosterone system, endothelial dysfunction, inflammation, proliferation, and phenotypic change in smooth muscle cells, and the hyperactivation of the sympathetic nervous system. MicroRNAs are also involved in the regulation of insulin signaling and blood glucose levels in T2D, and participate in lipid metabolism, adipogenesis, and adipocyte differentiation in obesity, with specific microRNA signatures involved in the pathogenesis of each disease. Many studies report the benefits promoted by exercise training in cardiovascular diseases by reducing blood pressure, glucose levels, and improving insulin signaling and lipid metabolism. The molecular mechanisms involved, however, remain poorly understood, especially regarding the participation of microRNAs in these processes. This review aimed to highlight microRNAs already known to be associated with SAH, T2D, and obesity, as well as their possible regulation by exercise training.

MicroRNA-296, a suppressor non-coding RNA, downregulates SGLT2 expression in lung cancer

Non-small cell lung cancer (NSCLC) is one of the most common types of cancer worldwide and has the highest mortality rate in China. MicroRNAs (miRNAs or miRs) are involved in tumorigenesis and their important role in cancer is becoming increasingly apparent. The expression of miR‑296‑5p in particular has been shown to be significantly downregulated in lung cancer. Sodium-glucose co-transporter-2 [SGLT2, also known as solute carrier family 5 member 2 (SLC5A2)] is an oncogene that promotes tumorigenesis. In this study, we aimed to determine the role of miR‑296‑5p in lung cancer and whether this involves the targeting of SGLT2. For this purpose, we examined miR‑296‑5p and SGLT2 expression in human lung cancer samples and cell lines by RT-qPCR and western blot analysis. In addition, the data analysis website TCGA was used for survival analysis with respect to SGLT2 expression. The effects of miR‑296‑5p were also examined on cell proliferation and cell cycle progression using respective assays. The results demonstrate that miR‑296‑5p is significantly downregulated in NSCLC tissues. Additionally, it is demonstrated that SGLT2 is directly targeted by miR‑296‑5p. Furthermore, our data reveal that the knockdown of SGLT2 using siRNA inhibits cell proliferation and impedes cell cycle progression. Collectively, data suggest that miR‑296‑5p not only inhibits NSCLC by downregulating SGLT2 expression, but also acts as a novel regulator of aberrant lung cancer cells to limit lung cancer progression.

MicroRNAs in islet hormone secretion

Pancreatic islet hormone secretion is central in the maintenance of blood glucose homeostasis. During development of hyperglycaemia, the β-cell is under pressure to release more insulin to compensate for increased insulin resistance. Failure of the β-cells to secrete enough insulin results in type 2 diabetes (T2D). MicroRNAs (miRNAs) are short non-coding RNA molecules suitable for rapid regulation of the changes in target gene expression needed in β-cell adaptations. Moreover, miRNAs are involved in the maintenance of α-cell and β-cell phenotypic identities via cell-specific, or cell-enriched expression. Although many of the abundant miRNAs are highly expressed in both cell types, recent research has focused on the role of miRNAs in β-cells. It has been shown that highly abundant miRNAs, such as miR-375, are involved in several cellular functions indispensable in maintaining β-cell phenotypic identity, almost acting as "housekeeping genes" in the context of hormone secretion. Despite the abundance and importance of miR-375, it has not been shown to be differentially expressed in T2D islets. On the contrary, the less abundant miRNAs such as miR-212/miR-132, miR-335, miR-130a/b and miR-152 are deregulated in T2D islets, wherein the latter three miRNAs were shown to play key roles in regulating β-cell metabolism. In this review, we focus on β-cell function and describe miRNAs involved in insulin biosynthesis and processing, glucose uptake and metabolism, electrical activity and Ca²⁺ -influx and exocytosis of the insulin granules. We present current status on miRNA regulation in α-cells, and finally we discuss the involvement of miRNAs in β-cell dysfunction underlying T2D pathogenesis.

MicroRNAs as Potential Regulators of Glutathione Peroxidases Expression and Their Role in Obesity and Related Pathologies

Glutathione peroxidases (GPxs) belong to the eight-member family of phylogenetically related enzymes with different cellular localization, but distinct antioxidant function. Several GPxs are important selenoproteins. Dysregulated GPx expression is connected with severe pathologies, including obesity and diabetes. We performed a comprehensive bioinformatic analysis using the programs miRDB, miRanda, TargetScan, and Diana in the search for hypothetical microRNAs targeting 3′untranslated regions (3´UTR) of GPxs. We cross-referenced the literature for possible intersections between our results and available reports on identified microRNAs, with a special focus on the microRNAs related to oxidative stress, obesity, and related pathologies. We identified many microRNAs with an association with oxidative stress and obesity as putative regulators of GPxs. In particular, miR-185-5p was predicted by a larger number of programs to target six GPxs and thus could play the role as their master regulator. This microRNA was altered by selenium deficiency and can play a role as a feedback control of selenoproteins’ expression. Through the bioinformatics analysis we revealed the potential connection of microRNAs, GPxs, obesity, and other redox imbalance related diseases.

MicroRNA-296: a promising target in the pathogenesis of atherosclerosis?

Atherosclerosis has been recognized as an inflammatory disease involving the vascular wall. MicroRNAs are a group of small noncoding RNAs to regulate gene expression at the transcriptional level through mRNA degradation or translation repression. Recent studies suggest that miR-296 may play crucial roles in the regulation of angiogenesis, inflammatory response, cholesterol metabolism, hypertension, cellular proliferation and apoptosis. In this review, we primarily discussed the molecular targets of miR-296 involved in the development of atherosclerosis, which may provide a basis for future investigation and a better understanding of the biological functions of miR-296 in atherosclerosis.

The Cells of the Islets of Langerhans

Islets of Langerhans are islands of endocrine cells scattered throughout the pancreas. A number of new studies have pointed to the potential for conversion of non-β islet cells in to insulin-producing β-cells to replenish β-cell mass as a means to treat diabetes. Understanding normal islet cell mass and function is important to help advance such treatment modalities: what should be the target islet/β-cell mass, does islet architecture matter to energy homeostasis, and what may happen if we lose a particular population of islet cells in favour of β-cells? These are all questions to which we will need answers for islet replacement therapy by transdifferentiation of non-β islet cells to be a reality in humans. We know a fair amount about the biology of β-cells but not quite as much about the other islet cell types. Until recently, we have not had a good grasp of islet mass and distribution in the human pancreas. In this review, we will look at current data on islet cells, focussing more on non-β cells, and on human pancreatic islet mass and distribution.

CircSMARCA5 Inhibits Migration of Glioblastoma Multiforme Cells by Regulating a Molecular Axis Involving Splicing Factors SRSF1/SRSF3/PTB

Circular RNAs (circRNAs) have recently emerged as a new class of RNAs, highly enriched in the brain and very stable within cells, exosomes and body fluids. To analyze their involvement in glioblastoma multiforme (GBM) pathogenesis, we assayed the expression of twelve circRNAs, physiologically enriched in several regions of the brain, through real-time PCR in a cohort of fifty-six GBM patient biopsies and seven normal brain parenchymas. We focused on hsa_circ_0001445 (circSMARCA5): it was significantly downregulated in GBM biopsies as compared to normal brain tissues (p-value < 0.00001, student's t-test), contrary to its linear isoform counterpart that did not show any differential expression (p-value = 0.694, student's t-test). Analysis of a public dataset revealed a negative correlation between the expression of circSMARCA5 and glioma's histological grade, suggesting its potential negative role in the progression to malignancy. Overexpressing circSMARCA5 in U87MG cells significantly decreased their migration, but not their proliferation rate. In silico scanning of circSMARCA5 sequence revealed an enrichment in binding motifs for several RNA binding proteins (RBPs), specifically involved in splicing. Among them, serine and arginine rich splicing factor 1 (SRSF1), a splicing factor known to be a positive controller of cell migration and known to be overexpressed in GBM, was predicted to bind circSMARCA5 by three different prediction tools. Direct interaction between circSMARCA5 and SRSF1 is supported by enhanced UV crosslinking and immunoprecipitation (eCLIP) data for SRSF1 in K562 cells from Encyclopedia of DNA Elements (ENCODE). Consistently, U87MG overexpressing circSMARCA5 showed an increased expression of serine and arginine rich splicing factor 3 (SRSF3) RNA isoform containing exon 4, normally skipped in a SRSF1-dependent manner, resulting in a non-productive non-sense mediated decay (NMD) substrate. Interestingly, SRSF3 is known to interplay with two other splicing factors, polypyrimidine tract binding protein 1 (PTBP1) and polypyrimidine tract binding protein 2 (PTBP2), that positively regulate glioma cells migration. Collectively, our data show circSMARCA5 as a promising druggable tumor suppressor in GBM and suggest that it may exert its function by tethering the RBP SRSF1.

Circulating MicroRNAs in Elderly Type 2 Diabetic Patients

The circulating microRNAs (miRNAs) associated with type 2 diabetes (T2D) in elderly patients are still being defined. To identify novel miRNA biomarker candidates for monitoring responses to sitagliptin in such patients, we prospectively studied 40 T2D patients (age > 65) with HbA1c levels of 7.5-9.0% on metformin. After collection of baseline blood samples (t₀), the dipeptidyl peptidase-IV (DPP-IV) inhibitor (DPP-IVi) sitagliptin was added to the metformin regimen, and patients were followed for 15 months. Patients with HbA1c < 7.5% or HbA1c reduction > 0.5% after 3 and 15 months of therapy were classified as "responders" (group R, n = 34); all others were classified as "nonresponders" (group NR, n = 6). Circulating miRNA profiling was performed on plasma collected in each group before and after 15 months of therapy (t₀ and t₁₅). Intra- and intergroup comparison of miRNA profiles pinpointed three miRNAs that correlated with responses to sitagliptin: miR-378, which is a candidate biomarker of resistance to this DPP-IVi, and miR-126-3p and miR-223, which are associated with positive responses to the drug. The translational implications are as immediate as evident, with the possibility to develop noninvasive diagnostic tools to predict drug response and development of chronic complications.

Next-generation sequencing-based microRNA profiling of mice testis subjected to transient heat stress

This study aimed to investigate the role of microRNA (miRNA) in heat stress-induced spermatogenic impairment. Testes from 15 adult ICR mice subjected to testicular hyperthermia at 43°C for 30 min and from 15 control mice were collected and pooled into 3 samples. Isolated RNA from these samples was subjected to small RNA high-throughput sequencing, and differentially expressed miRNAs were identified and validated using RT-PCR. The identified miRNAs were further subjected to Gene Ontology and KEGG analyses, which revealed significant enrichment for pathways potentially involved in heat stress-induced spermatogenic impairment. Additionally, a correlation analysis of the relative levels of validated miRNAs with germ cell apoptosis was performed. Of the 11 miRNAs identified as differentially expressed, 8 were validated as consistent with sequencing data. Further analyses suggested that the target genes of those miRNAs were involved in various pathways (e.g., ribosomal, HIF-1, MAPK) that may be critical to heat stress-induced testicular damage. Some identified miRNAs, including miR-449a-3p, miR-92a-1-5p, miR-423-3p, and miR-128-3p, correlated closely with germ cell apoptosis. The study results reveal a detailed miRNA profile of heat stress-induced testicular damage and highlight new and potentially important candidate targets in the process of male infertility.

Altered levels of circulating cytokines and microRNAs in lean and obese individuals with prediabetes and type 2 diabetes

Today obesity and type 2 diabetes (T2D) have both reached epidemic proportions. However, our current understanding of the primary mechanisms leading to these diseases is still limited due to the complex multifactorial nature of the underlying phenomena. We hypothesize that the levels of specific cytokines and miRNAs vary across the diabetes spectrum and unique signatures associated with them may serve as early biomarkers of the disease and provide insights into respective pathogenetic mechanisms. In this study, we measured the circulating levels of cytokines and microRNAs (miRNAs) in lean and obese humans with prediabetes (n = 21), T2D (n = 17), and healthy controls (n = 20) (ORIGINS trial, NCT02226640). Data were analyzed by fitting linear models adjusted for confounding variables (BMI, age, and gender in the diabetes context and age, gender, and diabetes status in the obesity context) and implementing nonparametric randomization-based tests for statistical inference. Group differences and correlations (r > 0.3) between variables with P < 0.05 were considered significant. False discovery rates (FDR) correcting for multiple testing were calculated using the Benjamini-Hochberg correction. We found a number of circulating cytokines and miRNAs deregulated in subjects with obesity, prediabetes, and T2D. Specifically, cytokines IL-6, IL-8, IL-10, IL-12, and SFRP4, as well as miRNAs miR-21, miR-24.1, miR-27a, miR-28-3p, miR-29b, miR-30d, miR-34a, miR-93, miR-126, miR-146a, miR-148, miR-150, miR-155, and miR-223, significantly changed across the diabetes spectrum, and were associated with measures of pancreatic islet β cell function and glycemic control, among others. Notably, SFRP4 was the only studied cytokine that was significantly associated with obesity, prediabetes, and T2D, which underscores the important role of this molecule during disease development and progression. Our data suggest that changes in circulating miRNAs and cytokines may have clinical utility as biomarkers of prediabetes.

Dysregulation of Placental miRNA in Maternal Obesity Is Associated With Pre- and Postnatal Growth

CONTEXT

Human placenta exhibits a specific microRNA (miRNA) expression pattern. Some of these miRNAs are dysregulated in pregnancy disorders such as preeclampsia and intrauterine growth restriction and are potential biomarkers for these pathologies.

OBJECTIVE

To study the placental miRNA profile in pregnant women with pregestational overweight/obesity (preOB) or gestational obesity (gestOB) and explore the associations between placental miRNAs dysregulated in maternal obesity and prenatal and postnatal growth.

METHODS

TaqMan Low Density Arrays and real-time polymerase chain reaction were used to profile the placental miRNAs in 70 pregnant women (20 preOB, 25 gestOB, and 25 control). Placentas and newborns were weighed at delivery, and infants were weighed at 1, 4, and 12 months of age.

RESULTS

Eight miRNAs were decreased in placentas from preOB or gestOB (miR-100, miR-1269, miR-1285, miR-181, miR-185, miR-214, miR-296, and miR-487) (all P < 0.05). Among them, miR-100, miR-1285, miR-296, and miR-487 were associated with maternal metabolic parameters (all P < 0.05) and were predictors of lower birth weight (all P < 0.05; R2 > 30%) and increased postnatal weight gain (all P < 0.05; R2 > 20%). In silico analysis showed that these miRNAs were related to cell proliferation and insulin signaling pathways. miR-296 was also present in plasma samples and associated with placental expression and prenatal and postnatal growth parameters (all P < 0.05).

CONCLUSIONS

We identified a specific placental miRNA profile in maternal obesity. Placental miRNAs dysregulated in maternal obesity may be involved in mediation of growth-promoting effects of maternal obesity on offspring and could be used as early markers of prenatal and postnatal growth.

Deciphering the role of microRNA - A step by step guide

MicroRNAs (miRNAs), are small non-coding RNAs of approximately 22 nucleotides in length, playing an important role in regulating gene expression post-transcriptionally. Understanding the effect of miRNA regulation in a pathway-specific manner unravels the approaches adopted to apprehend biological mechanisms, the information, which is scanty for researchers, not primed already for miR related research. Here, we describe a quick perspective in 5 steps with probable approaches and assays at every level to unravel the specific role of a microRNA, miR-145a-5p, as an example. This perspective as a guide would help in identifying novel targets for a microRNA, as shown for miR-145a-5p, which down-regulated the mRNA expression of ADD3 and BRCA2, using bioinformatic tools and experimental assays.

An 'alpha-beta' of pancreatic islet microribonucleotides

MicroRNAs (miRNAs) are cellular, short, non-coding ribonucleotides acting as endogenous posttranscriptional repressors following incorporation in the RNA-induced silencing complex. Despite being chemically and mechanistically very similar, miRNAs exert a multitude of different cellular effects by acting on mRNA species, whose gene-products partake in a wide array of processes. Here, the aim was to review the knowledge of miRNA expression and action in the islet of Langerhans. We have focused on: 1) physiological consequences of islet or beta cell specific inhibition of miRNA processing, 2) mechanisms regulating processing of miRNAs in islet cells, 3) presence and function of miRNAs in alpha versus beta cells - the two main cell types of islets, and 4) miRNA mediators of beta cell decompensation. It is clear that miRNAs regulate pancreatic islet development, maturation, and function in vivo. Moreover, processing of miRNAs appears to be altered by obesity, diabetes, and aging. A number of miRNAs (such as miR-7, miR-21, miR-29, miR-34a, miR-212/miR-132, miR-184, miR-200 and miR-375) are involved in mediating beta cell dysfunction and/or compensation induced by hyperglycemia, oxidative stress, cytotoxic cytokines, and in rodent models of fetal metabolic programming prediabetes and overt diabetes. Studies of human type 2 diabetic islets underline that these miRNA families could have important roles also in human type 2 diabetes. Furthermore, there is a genuine gap of knowledge regarding miRNA expression and function in pancreatic alpha cells. Progress in this area would be enhanced by improved in vitro alpha cell models and better tools for islet cell sorting.

Intracellular and extracellular miRNome deregulation in cellular models of NAFLD or NASH: Clinical implications

BACKGROUND & AIMS

Nonalcoholic fatty liver disease (NAFLD) represents the most common chronic liver disease in industrialized countries. NAFLD has the potential to progress through the inflammatory phase of nonalcoholic steatohepatitis (NASH) to fibrosis, cirrhosis, and hepatocellular carcinoma. Identifying patients at risk for this transition is a relevant clinical challenge. The complexity of these phenotypes in vivo made necessary the development of in vitro models in order to dissect the molecular signalling affected in NAFLD and NASH, but also to identify potential circulating biomarkers.

METHODS AND RESULTS

We profiled the expression of 754 cellular and medium-secreted human miRNAs in HepG2 cells after lipotoxic (Palmitate, model of NASH) or not-lipotoxic stimuli (Oleate-Palmitate, model of NAFLD). Results were validated through Single TaqMan assays. We performed computational analysis of miRNA targets and pathways. Oleate-palmitate treatment induced a variation of 2.8% and 10% of total miRNAs in cells and medium, respectively; palmitate treatment caused 10% and 19% intracellular and extracellular miRNA deregulation, respectively. We validated miR-126, miR-150, miR-223, miR-483-3p, miR-1226*, and miR-1290 deregulation. Through computational analysis, we observed that targets of both intracellular and extracellular DE miRNAs were involved in processes associated with the onset and progression of NAFLD and NASH, such as fatty acid metabolism, apoptosis and inflammation.

CONCLUSIONS

These data would be useful to elucidate the role of miRNAs in the pathogenesis and progression of the NAFLD spectrum, but they also allow the identification of novel potential biomarkers for differential diagnosis to be tested in vivo.

miRNA-296-3p modulates chemosensitivity of lung cancer cells by targeting CX3CR1

Lung cancer is the most common type of cancer-related death in developed countries. MicroRNAs (miRNAs) are small non-coding RNAs, which regulates gene expression in cancer. Recent studies demonstrate that the microRNA-293-3p (miR-293-3p) may play as an oncogene or a tumor suppressor. However, its expression and roles in non-small cell lung cancer (NSCLC) is not known. In this study, our purpose is to investigate the expression and roles of miR-296-3p in NSCLC. The findings indicated that miR296-3p inhibited NSCLC cell proliferation, enhance the drug resistance, and apoptosis. Data of luciferase reporter assays demonstrated that the CX3CR1 gene was a direct regulator of tumorsuppressive miR296-3p. Moreover, overexpressed CX3CR1 was confirmed in NSCLC clinical specimens. Inhibition of CX3CR1 could inhibit cancer cellular survival and increase chemotherapy sensitivity. There was a negative relationship between miR296-3p and CX3CR1 expression in NSCLC tissues. Our study elucidates that miR296-3p plays a suppressive role in NSCLC by inhibiting CX3CR1 expression.

Altered expression of uncoupling protein 2 in GLP-1-producing cells after chronic high glucose exposure: implications for the pathogenesis of diabetes mellitus

Glucagon-like peptide-1 (GLP-1) is a gut L-cell hormone that enhances glucose-stimulated insulin secretion. Several approaches that prevent GLP-1 degradation or activate the GLP-1 receptor are being used to treat type 2 diabetes mellitus (T2DM) patients. In T2DM, GLP-1 secretion has been suggested to be impaired, and this defect appears to be a consequence rather than a cause of impaired glucose homeostasis. However, although defective GLP-1 secretion has been correlated with insulin resistance, little is known about the direct effects of chronic high glucose concentrations, which are typical in diabetes patients, on GLP-1-secreting cell function. In the present study, we demonstrate that glucotoxicity directly affects GLP-1 secretion in GLUTag cells chronically exposed to high glucose. Our results indicate that this abnormality is associated with a decrease in ATP production due to the elevated expression of mitochondrial uncoupling protein 2 (UCP2). Furthermore, UCP2 inhibition using small interfering RNA (siRNA) and the application of glibenclamide, an ATP-sensitive potassium (KATP+) channel blocker, reverse the GLP-1 secretion defect induced by chronic high-glucose treatment. These results show that glucotoxicity diminishes the secretory responsiveness of GLP-1-secreting cells to acute glucose stimulation. We conclude that the loss of the incretin effect, as observed in T2DM patients, could at least partially depend on hyperglycemia, which is typical in diabetes patients. Such an understanding may not only provide new insight into diabetes complications but also ultimately contribute to the identification of novel molecular targets within intestinal L-cells for controlling and improving endogenous GLP-1 secretion.

Expression of miR-296-5p as predictive marker for radiotherapy resistance in early-stage laryngeal carcinoma

PURPOSE

Definitive radiation therapy is the mainstay of treatment for early stage laryngeal squamous cell carcinoma (LSCC). However, up to 30% of the patients do not respond to radiotherapy. Unfortunately, we are unable to predict which tumors are likely to respond to radiation, and which will be resistant and persist. Therefore, the development of novel markers to predict response to radiotherapy is urgently needed. This study was designed to evaluate the expression pattern of microRNAs (miRNAs) in LSCC in order to identify markers capable of segregating radioresistant and radiosensitive tumors and to investigate the relationship between the expression of these miRNAs and the prognosis of LSCC.

METHODS

The expression profile of 667 miRNAs was determined in an initial screening of nine early-stage LSCC samples (5 radioresistant and 4 radiosensitive) using TaqMan Low-Density Array (TLDA). Real-time polymerase chain reactions were performed to validate the expression of selected miRNAs in an expanded LSCC cohort (20 radioresistant and 14 radiosensitive). The miRNA expression level was scored as high or low based on the median of the expression in the LSCC samples.

RESULTS

A comprehensive miRNA expression profiling enabled the identification of four miRNAs (miR-296-5p miR-452, miR-183* and miR-200c) differentially expressed in radioresistant LSCC. Moreover, the analysis of additional 34 LSCC samples, confirmed the expression of miR-296-5p as significantly related to radioresistance (p = 0.002) as well as an association of this marker with recurrence (p = 0.025) in early stage laryngeal cancer.

CONCLUSIONS

This study indicates that miR-296-5p expression is associated with resistance to radiotherapy and tumor recurrence in early stage LSCC, showing the feasibility of this marker as a novel prognostic factor for this malignance. Furthermore, miR-296-5p expression could be helpful in the identification of tumors resistant to radiotherapy; thus aiding the clinicians in the choice of the best therapeutic scheme to be used in each case.

Differentially Expressed MicroRNA-483 Confers Distinct Functions in Pancreatic β- and α-Cells

Insulin secreted from pancreatic β-cells and glucagon secreted from pancreatic α-cells are the two major hormones working in the pancreas in an opposing manner to regulate and maintain a normal glucose homeostasis. How microRNAs (miRNAs), a population of non-coding RNAs so far demonstrated to be differentially expressed in various types of cells, regulate gene expression in pancreatic β-cells and its closely associated α-cells is not completely clear. In this study, miRNA profiling was performed and compared between pancreatic β-cells and their partner α-cells. One novel miRNA, miR-483, was identified for its highly differential expression in pancreatic β-cells when compared to its expression in α-cells. Overexpression of miR-483 in β-cells increased insulin transcription and secretion by targeting SOCS3, a member of suppressor of cytokine signaling family. In contrast, overexpression of miR-483 decreased glucagon transcription and secretion in α-cells. Moreover, overexpressed miR-483 protected against proinflammatory cytokine-induced apoptosis in β-cells. This correlates with a higher expression level of miR-483 and the expanded β-cell mass observed in the islets of prediabetic db/db mice. Together, our data suggest that miR-483 has opposite effects in α- and β-cells by targeting SOCS3, and the imbalance of miR-483 and its targets may play a crucial role in diabetes pathogenesis.

Secreted miR-34a in astrocytic shedding vesicles enhanced the vulnerability of dopaminergic neurons to neurotoxins by targeting Bcl-2

MicroRNAs (miRNAs) are a class of noncoding RNAs that regulates target gene expression at posttranscriptional level, leading to further biological functions. We have demonstrated that microvesicles (MVs) can deliver miRNAs into target cells as a novel way of intercellular communication. It is reported that in central nervous system, glial cells release MVs, which modulate neuronal function in normal condition. To elucidate the potential role of glial MVs in disease, we evaluated the effects of secreted astrocytic MVs on stress condition. Our results demonstrated that after Lipopolysaccharide (LPS) stimulation, astrocytes released shedding vesicles (SVs) that enhanced vulnerability of dopaminergic neurons to neurotoxin. Further investigation showed that increased astrocytic miR-34a in SVs was involved in this progress via targeting anti-apoptotic protein Bcl-2 in dopaminergic neurons. We also found that inhibition of astrocytic miR-34a after LPS stimulation can postpone dopaminergic neuron loss under neurotoxin stress. These data revealed a novel mechanism underlying astrocyte-neuron interaction in disease.

The Anti-Apoptotic Role of Berberine in Preimplantation Embryo In Vitro Development through Regulation of miRNA-21

Traditional Chinese medicinal herbs containing berberine have been historically used to prevent miscarriage. Here, we investigated whether the anti-apoptotic effects of berberine on pre-implantation embryonic development are regulated by miRNA-21. Mouse pronuclear embryos were cultured in medium with or without berberine, and some were then microinjected with a miRNA-21 inhibitor. The in vitro developmental rates of 2- and 4-cell embryos and blastocysts, blastocyst cell numbers, apoptotic rates, and apoptotic cell numbers were measured in each group. Furthermore, we examined the transcription levels of miRNA-21 and its target genes (caspase-3, PTEN, and Bcl-2) and their translation levels. Comparisons were made with in vivo-developed and untreated embryos. We found that berberine significantly increased the developmental rates and cell numbers of mouse blastocysts and decreased apoptotic cell rates in vitro. Berberine also significantly increased miRNA-21 and Bcl-2 transcription levels and significantly decreased caspase-3 and PTEN transcription levels. In embryos treated with a miRNA-21 inhibitor, the results followed the opposite trend; PTEN and caspase-3 transcription levels increased significantly, while the transcription level of Bcl-2 decreased significantly. Additionally, berberine treatment significantly increased the Bcl-2 protein level and significantly decreased the caspase-3 and PTEN protein levels in blastocysts, but there were no significant differences observed in the levels of these proteins in 2- and 4-cell embryos. This study revealed that miRNA-21 is important for pre-implantation embryonic development, especially blastocyst development in vitro. Berberine elevates miRNA-21 expression, decreases PTEN and caspase-3 levels, increases Bcl-2 levels, and exerts anti-apoptotic and pro-growth effects.

Aberrant expression of the microRNA cluster in 14q32 is associated with del(5q) myelodysplastic syndrome and lenalidomide treatment

Lenalidomide is a novel thalidomide analogue with immunomodulatory and antiangiogenic effects that has been successfully used for the treatment of low and intermediate-1 risk myelodysplastic syndromes (MDSs) with a del(5q) aberration. Because information about the influence of lenalidomide on the microRNA (miRNA) transcriptome is limited, we performed miRNA expression profiling of bone marrow CD34+ cells obtained from MDS patients with the del(5q) abnormality who had been subjected to lenalidomide treatment. To define differences in miRNA expression, we performed paired data analysis to compare the miRNA profiles of patients before and during lenalidomide treatment and those of healthy donors. The analysis showed that miRNAs clustering to the 14q32 region had a higher expression level in patient samples before treatment than in the healthy control samples, and this elevated expression was diminished following lenalidomide administration. Because some of the 14q32 miRNAs play important roles in hematopoiesis, stem cell differentiation, and apoptosis induction, the expression of this cluster may be associated with the pathophysiology of the disease.

Fibroblasts from patients with major depressive disorder show distinct transcriptional response to metabolic stressors

Major depressive disorder (MDD) is increasingly viewed as interplay of environmental stressors and genetic predisposition, and recent data suggest that the disease affects not only the brain, but the entire body. As a result, we aimed at determining whether patients with major depression have aberrant molecular responses to stress in peripheral tissues. We examined the effects of two metabolic stressors, galactose (GAL) or reduced lipids (RL), on the transcriptome and miRNome of human fibroblasts from 16 pairs of patients with MDD and matched healthy controls (CNTR). Our results demonstrate that both MDD and CNTR fibroblasts had a robust molecular response to GAL and RL challenges. Most importantly, a significant part (messenger RNAs (mRNAs): 26-33%; microRNAs (miRNAs): 81-90%) of the molecular response was only observed in MDD, but not in CNTR fibroblasts. The applied metabolic challenges uncovered mRNA and miRNA signatures, identifying responses to each stressor characteristic for the MDD fibroblasts. The distinct responses of MDD fibroblasts to GAL and RL revealed an aberrant engagement of molecular pathways, such as apoptosis, regulation of cell cycle, cell migration, metabolic control and energy production. In conclusion, the metabolic challenges evoked by GAL or RL in dermal fibroblasts exposed adaptive dysfunctions on mRNA and miRNA levels that are characteristic for MDD. This finding underscores the need to challenge biological systems to bring out disease-specific deficits, which otherwise might remain hidden under resting conditions.

SIRT1 signalling protects mouse oocytes against oxidative stress and is deregulated during aging

STUDY QUESTION

Is SIRT1 involved in the oxidative stress (OS) response in mouse oocytes?

SUMMARY ANSWER

SIRT1 plays a pivotal role in the adaptive response of mouse germinal vesicle (GV) oocytes to OS and promotes a signalling cascade leading to up-regulation of the MnSod gene.

WHAT IS KNOWN ALREADY

OS is known to continuously threaten acquisition and maintenance of oocyte developmental potential during in vivo processes and in vitro manipulations. Previous studies in somatic cells have provided strong evidence for the role of SIRT1 as a sensor of the cell redox state and a protector against OS and aging.

STUDY DESIGN, SIZE, DURATION

GV oocytes obtained from young (4-8 weeks) and reproductively old (48-52 weeks) CD1 mice were blocked in the prophase stage by 0.5 µM cilostamide. Groups of 30 oocytes were exposed to 25 µM H2O2 and processed following different times for the analysis of intracellular localization of SIRT1 and FOXO3A, and evaluation of Sirt1, miRNA-132, FoxO3a and MnSod gene expression. Another set of oocytes was cultured in the presence or absence of the SIRT1-specific inhibitor Ex527, and exposed to H2O2 in order to assess the involvement of SIRT1 in the activation of a FoxO3a-MnSod axis and ROS detoxification. In the last part of this study, GV oocytes were maturated in vitro in the presence of different Ex527 concentrations (0, 2.5, 5, 10, 20 µM) and assessed for maturation rates following 16 h. Effects of Ex527 on spindle morphology and ROS levels were also evaluated.

PARTICIPANTS/MATERIALS, SETTING, METHODS

SIRT1 and FOXO3A intracellular distribution in response to OS was investigated by immunocytochemistry. Real-time RT-PCR was employed to analyse Sirt1, miR-132, FoxO3a and MnSod gene expression. Reactive oxygen species (ROS) production was evaluated by in vivo measurement of carboxy-H2DCF diacetate labelling. Spindle and chromosomal distribution in in vitro matured oocytes were analysed by immunocytochemistry and DNA fluorescent labelling, respectively.

MAIN RESULTS AND THE ROLE OF CHANCE

Specific changes in the intracellular localization of SIRT1 and up-regulation of Sirt1 gene were detected in mouse oocytes in response to OS. Moreover, increased intracellular ROS were observed when SIRT1 activity was inhibited by Ex527. In aged oocytes Sirt1 was expressed more than in young oocytes but SIRT1 protein was undetectable. Upon OS, significant changes in miR-132 micro-RNA, a validated Sirt1 modulator, were observed. A negative correlation between Sirt1 mRNA and miR-132 levels was observed when young oocytes exposed to OS were compared with young control oocytes, and when aged oocytes were compared with young control oocytes. FoxO3a and MnSod transcripts were increased upon OS with the same kinetics as Sirt1 transcripts, and up-regulation of MnSod gene was prevented by oocyte treatment with Ex527, indicating that SIRT1 acts upstream to the FoxO3a-MnSod axis. Finally, the results of the in vitro maturation assay suggested that SIRT1 might be involved in oocyte maturation by regulating the redox state and ensuring normal spindle assembly.

LIMITATIONS, REASONS FOR CAUTION

The main limitation of this study was the absence of direct quantification of SIRT1 enzymatic activity due to the lack of an appropriately sensitive method.

WIDER IMPLICATIONS OF THE FINDINGS

The present findings may provide a valuable background for studying the regulation of SIRT1 during oogenesis and its relevance as a sensor of oocyte redox state and energy status. The antioxidant response orchestrated by SIRT1 in oocytes seems to decrease with aging. This suggests that SIRT1 could be an excellent pharmacological target for improving oocyte quality and IVF outcome in aging or aging-like diseases.

STUDY FUNDING/COMPETING INTERESTS

The work was supported by the Ministero dell'Università e della Ricerca Scientifica (MIUR) to C.T., F.A., C.D., A.M.D. The authors declare no conflict of interest.

CEBPA exerts a specific and biologically important proapoptotic role in pancreatic β cells through its downstream network targets

Transcription factor CEBPA has been widely studied for its involvement in hematopoietic cell differentiation and causal role in hematological malignancies. It is shown for the first time that CEBPA also has a causal role in cytokine-induced apoptosis of pancreas β cells.

Transcription factor CEBPA has been widely studied for its involvement in hematopoietic cell differentiation and causal role in hematological malignancies. We demonstrate here that it also performs a causal role in cytokine-induced apoptosis of pancreas β cells. Treatment of two mouse pancreatic α and β cell lines (αTC1-6 and βTC1) with proinflammatory cytokines IL-1β, IFN-γ, and TNF-α at doses that specifically induce apoptosis of βTC1 significantly increased the amount of mRNA and protein encoded by Cebpa and its proapoptotic targets, Arl6ip5 and Tnfrsf10b, in βTC1 but not in αTC1-6. Cebpa knockdown in βTC1 significantly decreased cytokine-induced apoptosis, together with the amount of Arl6ip5 and Tnfrsf10b. Analysis of the network comprising CEBPA, its targets, their first interactants, and proteins encoded by genes known to regulate cytokine-induced apoptosis in pancreatic β cells (genes from the apoptotic machinery and from MAPK and NFkB pathways) revealed that CEBPA, ARL6IP5, TNFRSF10B, TRAF2, and UBC are the top five central nodes. In silico analysis further suggests TRAF2 as trait d'union node between CEBPA and the NFkB pathway. Our results strongly suggest that Cebpa is a key regulator within the apoptotic network activated in pancreatic β cells during insulitis, and Arl6ip5, Tnfrsf10b, Traf2, and Ubc are key executioners of this program.

The pancreatic β-cell transcriptome and integrated-omics

PURPOSE OF REVIEW

β Cells represent one of many cell types in heterogeneous pancreatic islets and play the central role in maintaining glucose homeostasis, such that disrupting β-cell function leads to diabetes. This review summarizes the methods for isolating and characterizing β cells, and describes integrated 'omics' approaches used to define the β cell by its transcriptome and proteome.

RECENT FINDINGS

RNA sequencing and mass spectrometry-based protein identification have now identified RNA and protein profiles for mouse and human pancreatic islets and β cells, and for β-cell lines. Recent publications have outlined these profiles and, more importantly, have begun to assign the presence or absence of specific genes and regulatory molecules to β-cell function and dysfunction. Overall, researchers have focused on understanding the pathophysiology of diabetes by connecting genome, transcriptome, proteome, and regulatory RNA profiles with findings from genome-wide association studies.

SUMMARY

Studies employing these relatively new techniques promise to identify specific genes or regulatory RNAs with altered expression as β-cell function begins to deteriorate in the spiral toward the development of diabetes. The ultimate goal is to identify the potential therapeutic targets to prevent β-cell dysfunction and thereby better treat the individual with diabetes.

VIDEO ABSTRACT

http://links.lww.com/COE/A5.