MicroRNA-1298 is regulated by DNA methylation and affects vascular smooth muscle cell function by targeting connexin 43

Neuroprotective effects of G9a inhibition through modulation of peroxisome-proliferator activator receptor gamma-dependent pathways by miR-128

JOURNAL/nrgr/04.03/01300535-202419110-00033/figure1/v/2024-03-08T184507Z/r/image-tiff Dysregulation of G9a, a histone-lysine N-methyltransferase, has been observed in Alzheimer's disease and has been correlated with increased levels of chronic inflammation and oxidative stress. Likewise, microRNAs are involved in many biological processes and diseases playing a key role in pathogenesis, especially in multifactorial diseases such as Alzheimer's disease. Therefore, our aim has been to provide partial insights into the interconnection between G9a, microRNAs, oxidative stress, and neuroinflammation. To better understand the biology of G9a, we compared the global microRNA expression between senescence-accelerated mouse-prone 8 (SAMP8) control mice and SAMP8 treated with G9a inhibitor UNC0642. We found a downregulation of miR-128 after a G9a inhibition treatment, which interestingly binds to the 3' untranslated region (3'-UTR) of peroxisome-proliferator activator receptor γ (PPARG) mRNA. Accordingly, Pparg gene expression levels were higher in the SAMP8 group treated with G9a inhibitor than in the SAMP8 control group. We also observed modulation of oxidative stress responses might be mainly driven Pparg after G9a inhibitor. To confirm these antioxidant effects, we treated primary neuron cell cultures with hydrogen peroxide as an oxidative insult. In this setting, treatment with G9a inhibitor increases both cell survival and antioxidant enzymes. Moreover, up-regulation of PPARγ by G9a inhibitor could also increase the expression of genes involved in DNA damage responses and apoptosis. In addition, we also described that the PPARγ/AMPK axis partially explains the regulation of autophagy markers expression. Finally, PPARγ/GADD45α potentially contributes to enhancing synaptic plasticity and neurogenesis after G9a inhibition. Altogether, we propose that pharmacological inhibition of G9a leads to a neuroprotective effect that could be due, at least in part, by the modulation of PPARγ-dependent pathways by miR-128.

Noncoding RNAs in Vascular Cell Biology and Restenosis

In-stent restenosis (ISR), characterised by ≥50% re-narrowing of the target vessel, is a common complication following stent implantation and remains a significant challenge to the long-term success of angioplasty procedures. Considering the global burden of cardiovascular diseases, improving angioplasty patient outcomes remains a key priority. Noncoding RNAs (ncRNAs) including microRNA (miRNA), long noncoding RNA (lncRNA) and circular RNA (circRNA) have been extensively implicated in vascular cell biology and ISR through multiple, both distinct and overlapping, mechanisms. Vascular smooth muscle cells, endothelial cells and macrophages constitute the main cell types involved in the multifactorial pathophysiology of ISR. The identification of critical regulators exemplified by ncRNAs in all these cell types and processes makes them an exciting therapeutic target in the field of restenosis. In this review, we will comprehensively explore the potential functions and underlying molecular mechanisms of ncRNAs in vascular cell biology in the context of restenosis, with an in-depth focus on vascular cell dysfunction during restenosis development and progression. We will also discuss the diagnostic biomarker and therapeutic target potential of ncRNAs in ISR. Finally, we will discuss the current shortcomings, challenges, and perspectives toward the clinical application of ncRNAs.

The Etiology and Molecular Mechanism Underlying Smooth Muscle Phenotype Switching in Intimal Hyperplasia of Vein Graft and the Regulatory Role of microRNAs

Mounting evidence suggests that the phenotypic transformation of venous smooth muscle cells (SMCs) from differentiated (contractile) to dedifferentiated (proliferative and migratory) phenotypes causes excessive proliferation and further migration to the intima leading to intimal hyperplasia, which represents one of the key pathophysiological mechanisms of vein graft restenosis. In recent years, numerous miRNAs have been identified as specific phenotypic regulators of vascular SMCs (VSMCs), which play a vital role in intimal hyperplasia in vein grafts. The review sought to provide a comprehensive overview of the etiology of intimal hyperplasia, factors affecting the phenotypic transformation of VSMCs in vein graft, and molecular mechanisms of miRNAs involved in SMCs phenotypic modulation in intimal hyperplasia of vein graft reported in recent years.

Identification of Key microRNAs in Diabetes Mellitus Erectile Dysfunction Rats with Stem Cell Therapy by Bioinformatic Analysis of Deep Sequencing Data

PURPOSE

Diabetes mellitus erectile dysfunction (DMED) is a common resulting complication of diabetes. Studies have shown mesenchymal stem cell (MSC)-based therapy was beneficial in alleviating erectile function of DMED rats. While the pathogenesis of DMED and the mechanism MSCs actions are unclear.

MATERIALS AND METHODS

We constructed a rat model of DMED with or without intracavernous injection of MSCs, and performed microRNA (miRNA) sequencing of corpora cavernosa tissues.

RESULTS

We identified three overlapping differentially expressed miRNAs (rno-miR-1298, rno-miR-122-5p, and rno-miR-6321) of the normal control group, DMED group, and DMED+MSCs group. We predicted 285 target genes of three miRNAs through RNAhybrid and miRanda database and constructed a miRNA-target gene network through Cytoscape. Next, we constructed protein-protein interaction networks through STRING database and identified the top 10 hub genes with highest connectivity scores. Five GO terms including cellular response to growth factor stimulus (GO:0071363), ossification (GO:0001503), response to steroid hormone (GO:0048545), angiogenesis (GO:0001525), positive regulation of apoptotic process (GO:0043065), and one Reactome pathway (Innate Immune System) were significantly enriched by 10 hub genes using the Metascape database. We selected the GSE2457 dataset to validate the expression of hub genes and found only the expression of B4galt1 was statistically different (p<0.001). B4galt1 was highly expressed in penile tissues of diabetic rats and would be negatively regulated by rno-miR-1298.

CONCLUSIONS

Three key miRNAs were identified in DMED rats with stem cell therapy and the miR-1298/B4GalT1 axis might exert function in stem cell therapy for ED.

An update on the phenotypic switching of vascular smooth muscle cells in the pathogenesis of atherosclerosis

Vascular smooth muscle cells (VSMCs) are involved in phenotypic switching in atherosclerosis. This switching is characterized by VSMC dedifferentiation, migration, and transdifferentiation into other cell types. VSMC phenotypic transitions have historically been considered bidirectional processes. Cells can adopt a physiological contraction phenotype or an alternative "synthetic" phenotype in response to injury. However, recent studies, including lineage tracing and single-cell sequencing studies, have shown that VSMCs downregulate contraction markers during atherosclerosis while adopting other phenotypes, including macrophage-like, foam cell, mesenchymal stem-like, myofibroblast-like, and osteochondral-like phenotypes. However, the molecular mechanism and processes regulating the switching of VSMCs at the onset of atherosclerosis are still unclear. This systematic review aims to review the critical outstanding challenges and issues that need further investigation and summarize the current knowledge in this field.

The promoting role of Cx43 on the proliferation and migration of arterial smooth muscle cells for angiotensin II-dependent hypertension

BACKGROUND

Recent studies have shown that endothelin-1 and angiotensin II (AngII) can increase gap junctional intercellular communication (GJIC) by activating Mitogen-activated protein kinases (MAPKs) pathway. However, not only the precise interaction of AngII with Connexin43(Cx43) and the associated functions remain unclear, but also the regulatory role of Cx43 on the AngII-mediated promotion proliferation and migration of VSMCs is poorly understood.

MATERIAL AND METHODS

Our research applicated pressure myography measurements, immunofluorescence and Western blot analyses to investigate the changes in physiological indicators in spontaneously hypertensive rats (SHRs) and AngII-stimulated proliferation and migration of A7r5 SMCs(Rat vascular smooth muscle cells). The aim was to elucidate the role of CX43 in hypertension induced by AngII.

RESULTS

Chronic ramipril (angiotensin converting enzyme inhibitor) management for SHRs significantly attenuated blood pressure and blood vessel wall thickness, also reduced contraction rate in the cerebral artery. The cerebral artery contraction rates, mRNA and protein expression of Cx43, osteopontin (OPN) and proliferating cell nuclear antigen (PCNA) protein expression in the SHR + ramipril and SHR + ramipril + carbenoxolone (CBX, Cx43 specific blocker) groups were significantly lower than those in the SHR group. Cx43 protein expression and Ser368 phosphorylated Cx43 protein levels increased significantly in AngII-stimulated A7r5 cells. However, the levels of phosphorylated Cx43 decreased after pre-treatment with candesartan (AT1 receptor blocker), GF109203X (protein kinase C (PKC) blocker) and U0126 (mitogen-activated protein kinases/extracellular signal-regulated kinase1/2(MEK/ERK1/2)-specific blocker) in AngII-stimulated A7r5 cells. Cx43 was widely distributed in the cell membrane, nucleus, and cytoplasm of the SMCs. Furthermore, pre-treatment of the AngII- stimulated A7r5 cells with Gap26 (Cx43 blocker) significantly inhibited cell migration and decreased the expression levels of MEK1/2, ERK1/2, P-MEK1/2, and P-ERK1/2.

CONCLUSION

Our research confirms that Cx43 plays an important role in the regulation of proliferation and migration of VSMCs via MEK/ERK and PKC signal pathway in AngII-dependent hypertension.

Roles of MicroRNAs in Peripheral Artery In-Stent Restenosis after Endovascular Treatment

Endovascular repair including percutaneous transluminal angioplasty (PTA) and stent implantation has become the standard approach for the treatment of peripheral arterial disease; however, restenosis is still the main limited complication for the long-term success of the endovascular repair. Endothelial denudation and regeneration, inflammatory response, and neointimal hyperplasia are major pathological processes occurring during in-stent restenosis (ISR). MicroRNAs exhibit great potential in regulating several vascular biological events in different cell types and have been identified as novel therapeutic targets as well as biomarkers for ISR prevention. This review summarized recent experimental and clinical studies on the role of miRNAs in ISR modification, with the aim of unraveling the underlying mechanism and potential therapeutic strategy of ISR.

MicroRNA-1298-5p inhibits the tumorigenesis of breast cancer by targeting E2F1

Studies performed in the last two decades have identified microRNA (miR)-1298-5p to display tumor-suppressive functions in several types of malignancy. In addition, the regulatory role of E2F transcription factor 1 (E2F1) has been reported in multiple types of cancer, including breast cancer (BC). However, whether miR-1298-5p participates in BC progression and whether a regulatory association exists between miR-1298-5p and E2F1 remains to be explored. The present study aimed to determine the role of miR-1298-5p and its interaction with E2F1 in BC. The expression of miR-1298-5p and E2F1 was examined by reverse transcription-quantitative PCR and western blot assays. The viability and proliferative capacity of BC cells were evaluated by Cell Counting Kit-8 and 5-bromo-2′-deoxyuridine assays, respectively. The apoptotic rate was assessed by the caspase-3 activity assay and flow cytometry; the protein expression levels of vimentin and E-cadherin were evaluated by western blotting. In addition, the adhesive and migratory abilities of BC cells were determined by conducting cell adhesion and wound healing assay, respectively. The target relationship between miR-1298-5p and E2F1 was validated by the luciferase reporter assay. The results of the present study revealed that the levels of miR-1298-5p were downregulated in BC tissues and cells compared with those in normal breast tissues and cells, respectively. In addition, miR-1298-5p was demonstrated to inhibit the proliferation, adhesion and migration of BC cells and to promote BC cell apoptosis. E2F1 was verified as a target gene of miR-1298-5p using the luciferase reporter assay. Additionally, E2F1 exhibited an opposite expression pattern compared with that of miR-1298-5p in BC tissues. Furthermore, the downregulation of miR-1298-5p in BC cells was reversed by silencing E2F1. Overall, the results of the present study suggested that miR-1298-5p repressed BC cell proliferation, adhesion and migration, and enhanced BC cell apoptosis by downregulating E2F1.

Clinical significance of miR-1298 in cervical cancer and its biological function in vitro

Cervical cancer is one of the most malignant tumors in women. miR-1298 was reported to be abnormally expressed and serve crucial role in tumorigenesis of several types of cancer; however, the role of miR-1298 in cervical cancer remains unknown. The present study aimed to evaluate the clinical and biological significance of miR-1298 in cervical cancer. To do so, the expression level of miR-1298 in cervical cancer tissues and cells was evaluated by reverse transcription quantitative PCR. Kaplan-Meier survival analysis and Cox regression analysis were used to explore the prognostic significance of miR-1298 in patients with cervical cancer. Cell Counting Kit-8 and Transwell migration and invasion assays were used to evaluate the effect of miR-1298 on the proliferative, migratory and invasive abilities of cervical cancer cells, respectively. The expression of miR-1298 was lower in cancer tissues and cells compared with normal tissues and cells. Furthermore, miR-1298 expression was associated with lymph node metastasis, tumor diameter and staging from the International Federation of Gynecology and Obstetrics. In addition, patients with low miR-1298 expression had poorer overall survival. These findings suggested that miR-1298 may be considered as an independent prognostic factor for patients with cervical cancer. Furthermore, the results demonstrated that miR-1298 knockdown could promote tumor cell proliferation and migratory and invasive abilities. In addition, nucleus accumbens-associated 1 (NACC1) was demonstrated to be a direct target of miR-1298. Taken together, these findings indicated that miR-1298 overexpression may be considered as a prognostic biomarker for cervical cancer and that miR-1298 may play an inhibitor role in cervical cancer by targeting NACC1.

Out-of-Field Hippocampus from Partial-Body Irradiated Mice Displays Changes in Multi-Omics Profile and Defects in Neurogenesis

The brain undergoes ionizing radiation exposure in many clinical situations, particularly during radiotherapy for brain tumors. The critical role of the hippocampus in the pathogenesis of radiation-induced neurocognitive dysfunction is well recognized. The goal of this study is to test the potential contribution of non-targeted effects in the detrimental response of the hippocampus to irradiation and to elucidate the mechanisms involved. C57Bl/6 mice were whole body (WBI) or partial body (PBI) irradiated with 0.1 or 2.0 Gy of X-rays or sham irradiated. PBI consisted of the exposure of the lower third of the mouse body, whilst the upper two thirds were shielded. Hippocampi were collected 15 days or 6 months post-irradiation and a multi-omics approach was adopted to assess the molecular changes in non-coding RNAs, proteins and metabolic levels, as well as histological changes in the rate of hippocampal neurogenesis. Notably, at 2.0 Gy the pattern of early molecular and histopathological changes induced in the hippocampus at 15 days following PBI were similar in quality and quantity to the effects induced by WBI, thus providing a proof of principle of the existence of out-of-target radiation response in the hippocampus of conventional mice. We detected major alterations in DAG/IP3 and TGF-β signaling pathways as well as in the expression of proteins involved in the regulation of long-term neuronal synaptic plasticity and synapse organization, coupled with defects in neural stem cells self-renewal in the hippocampal dentate gyrus. However, compared to the persistence of the WBI effects, most of the PBI effects were only transient and tended to decrease at 6 months post-irradiation, indicating important mechanistic difference. On the contrary, at low dose we identified a progressive accumulation of molecular defects that tended to manifest at later post-irradiation times. These data, indicating that both targeted and non-targeted radiation effects might contribute to the pathogenesis of hippocampal radiation-damage, have general implications for human health.

MicroRNA-130a inhibits proliferation of vascular smooth muscle cells by suppressing autophagy via ATG2B

Numerous microRNAs participate in regulating the pathological process of atherosclerosis. We have found miR-130a is one of the most significantly down-regulated microRNAs in arteriosclerosis obliterans. Our research explored the function of miR-130a in regulating proliferation by controlling autophagy in arteriosclerosis obliterans development. A Gene Ontology (GO) enrichment analysis of miR-130a target genes indicated a correlation between miR-130a and cell proliferation. Thus, cell cycle, CCK-8 assays and Western blot analysis were performed, and the results indicated that miR-130a overexpression in vascular smooth muscle cells (VSMCs) significantly attenuated cell proliferation, which was validated by an in vivo assay in a rat model. Moreover, autophagy is thought to be involved in the regulation of proliferation. As our results indicated, miR-130a could inhibit autophagy, and ATG2B was predicted to be a target of miR-130a. The autophagy inhibition effect of miR-130a overexpression was consistent with the effect of ATG2B knockdown. The results that ATG2B plasmids and miR-130a mimics were cotransfected in VSMCs further confirmed our conclusion. In addition, by using immunohistochemistry, the positive results of LC3 II/I and ATG2B in the rat model and artery vascular tissues from the patient were in accordance with in vitro data. In conclusion, our data demonstrate that miR-130a inhibits VSMCs proliferation via ATG2B, which indicates that miR-130a could be a potential therapeutic target that regulates autophagy in atherosclerosis obliterans.

Connexins: Key Players in the Control of Vascular Plasticity and Function

Of the 21 members of the connexin family, 4 (Cx37, Cx40, Cx43, and Cx45) are expressed in the endothelium and/or smooth muscle of intact blood vessels to a variable and dynamically regulated degree. Full-length connexins oligomerize and form channel structures connecting the cytosol of adjacent cells (gap junctions) or the cytosol with the extracellular space (hemichannels). The different connexins vary mainly with regard to length and sequence of their cytosolic COOH-terminal tails. These COOH-terminal parts, which in the case of Cx43 are also translated as independent short isoforms, are involved in various cellular signaling cascades and regulate cell functions. This review focuses on channel-dependent and -independent effects of connexins in vascular cells. Channels play an essential role in coordinating and synchronizing endothelial and smooth muscle activity and in their interplay, in the control of vasomotor actions of blood vessels including endothelial cell reactivity to agonist stimulation, nitric oxide-dependent dilation, and endothelial-derived hyperpolarizing factor-type responses. Further channel-dependent and -independent roles of connexins in blood vessel function range from basic processes of vascular remodeling and angiogenesis to vascular permeability and interactions with leukocytes with the vessel wall. Together, these connexin functions constitute an often underestimated basis for the enormous plasticity of vascular morphology and function enabling the required dynamic adaptation of the vascular system to varying tissue demands.

Aberration methylation of miR-34b was involved in regulating vascular calcification by targeting Notch1

Vascular calcification is one of the most important factors for cardiovascular and all-cause mortality in patients with end-stage renal diseases (ESRD). The current study was aimed to investigate the function and mechanisms of miR-34b on the calcification of vascular smooth muscle cells (VSMCs) both in vitro and in vivo. We found that the expression of miR-34b was significantly suppressed in VSMCs with high inorganic phosphate (Pi) treatment, as well as mouse arteries derived from 5/6 nephrectomy with a high-phosphate diet (0.9% Pi, 5/6 NTP) and human renal arteries from uraemia patients. Overexpression of miR-34b alleviated calcification of VSMCs, while VSMCs calcification was enhanced by inhibiting the expression of miR-34b. Bisulphite sequencing PCR (BSP) uncovered that CpG sites upstream of miR-34b DNA were hypermethylated in calcified VSMCs and calcified arteries due to 5/6 NTP, as well as calcified renal arterial tissues from uraemia patients. Meantime, increased DNA methyltransferase 3a (DNMT3a) resulted in the hypermethylation of miR-34b in VSMCs, while 5-aza-2′-deoxycytidine (5-aza) reduced the methylation rate of miR-34b and restored the expression of miR-34b in VSMCs. When DNMT3a was knocked down using DNMT3a siRNA, the effect of 3.5 mM of Pi on calcification of VSMCs was abrogated. In addition, Notch1 was validated as the functional target of miR-34b and involved in the process of calcification of VSMCs. Taken together, our data showed a specific role for miR-34b in regulating calcification of VSMCs both in vitro and in vivo, which was regulated by upstream DNA methylation of miR-34b and modulated by the downstream target gene expression, Notch1. These results suggested that modulation of miR-34b may offer new insight into a novel therapeutic approach for vascular calcification.

TIM‑3 inhibits PDGF‑BB‑induced atherogenic responses in human artery vascular smooth muscle cells

Increasing evidence suggests that T-cell immunoglobulin and mucin domain 3 (TIM-3) displays anti-atherosclerotic effects, but its role in vascular smooth muscle cells (VSMCs) has not been reported. The present study aimed to investigate the function of TIM-3 and its roles in human artery VSMCs (HASMCs). A protein array was used to investigate the TIM-3 protein expression profile, which indicated that TIM-3 expression was increased in the serum of patients with lower extremity arteriosclerosis obliterans disease (LEAOD) compared with healthy individuals. Immunohistochemistry and western blotting of arterial tissue further revealed that TIM-3 expression was increased in LEAOD artery tissue compared with normal artery tissue. Additionally, platelet-derived growth factor-BB (PDGF-BB) displayed a positive correlation with TIM-3 expression in HASMCs. TIM-3 decreased the migration and proliferation of PDGF-BB-induced HASMCs, and anti-TIM-3 blocked the effects of TIM-3. The effect of TIM-3 on the proliferation and migration of HASMCs was further investigated using LV-TIM-3-transduced cells. The results revealed that TIM-3 also inhibited PDGF-BB-induced expression of the inflammatory factors interleukin-6 and tumor necrosis factor-α by suppressing NF-κB activation. In summary, the present study revealed that TIM-3 displayed a regulatory role during the PDGF-BB-induced inflammatory reaction in HASMCs, which indicated that TIM-3 may display anti-atherosclerotic effects.

Screening and functional prediction of differentially expressed circRNAs in proliferative human aortic smooth muscle cells

Vascular smooth muscle cell (VSMC) proliferation is the pathological base of vascular remodelling diseases. Circular RNAs (circRNAs) are important regulators involved in various biological processes. However, the function of circRNAs in VSMC proliferation regulation remains largely unknown. This study was conducted to identify the key differentially expressed circRNAs (DEcircRNAs) and predict their functions in human aortic smooth muscle cell (HASMC) proliferation. To achieve this, DEcircRNAs between proliferative and quiescent HASMCs were detected using a microarray, followed by quantitative real-time RT-PCR validation. A DEcircRNA-miRNA-DEmRNA network was constructed, and functional annotation was performed using Gene Ontology (GO) and KEGG pathway analysis. The function of hsa_circ_0002579 in HASMC proliferation was analysed by Western blot. The functional annotation of the DEcircRNA-miRNA-DEmRNA network indicated that the four DEcircRNAs might play roles in the TGF-β receptor signalling pathway, Ras signalling pathway, AMPK signalling pathway and Wnt signalling pathway. Twenty-seven DEcircRNAs with coding potential were screened. Hsa_circ_0002579 might be a pro-proliferation factor of HASMC. Overall, our study identified the key DEcircRNAs between proliferative and quiescent HASMCs, which might provide new important clues for exploring the functions of circRNAs in vascular remodelling diseases.

Non-coding RNAs as Epigenetic Gene Regulators in Cardiovascular Diseases

Epigenetic gene regulations can be considered as de-novo initiation of abnormal molecular signaling events whose regulation is otherwise required during normal or specific developmental stages of the organisms. Primarily, three different mechanisms have been identified to participate in epigenetic gene regulations which include, DNA methylation, non-coding RNA species (microRNAs [miRNA], and long non-coding RNAs [LNC-RNA]) and histone modifications. These de-novo epigenetic mechanisms have been associated with altered normal cellular functions which eventually facilitate normal cells to transition into an abnormal phenotype. Among the three modes of regulation, RNA species which are usually considered to be less stable, can be speculated to initiate instant alterations in gene expression compared to DNA methylation or histone modifications. However, LNC-RNAs appear to be more stable in the cells than the other RNA species. Moreover, there is increasing literature which clearly suggests that a single specific LNC-RNA can regulate multiple mechanisms and disease phenotypes. With specific focus on cardiovascular diseases, here we attempt to provide UpToDate information on the functional role of miRNAs and LNC-RNAs. Here we discuss the role of these epigenetic mediators in different components of cardiovascular disease which include physiopathological heart development, athersclerosis, retenosis, diabetic hearts, myocardial infarction, ischemia-reperfusion, heart valve disease, aortic aneurysm, osteogenesis, angiogenesis and hypoxia in the heart. While there is abundant literature support that shows the involvement of many LNC-RNAs and miRNAs in cardiovascular diseases, very few RNA species have been identified which regulate epigenetic mechanisms which is the current focus in this article. Understanding the role of these RNA species in regulating epigenetic mechanisms in different cell types causing cardiovascular disease, would advance the field and promote disease prevention approaches that are aimed to target epigenetic mechanisms.

Hesperidin suppressed hepatic precancerous lesions via modulation of exophagy in rats

The enormous cost of modern medicines warrants alternative strategies for the better management of hepatocellular carcinoma. Recently, exosomes have been shown to relay the oncogenic information through the horizontal transfer of RNAs between the cells. In this study, we modulated exosomal production and autophagy (exophagy) by the administration of hesperidin and evaluated its effect on the development of hepatic precancerous lesion (HPC) in rats. Diethylnitrosamine and 2-acetylaminofluorene were used in vivo to induce HPC in rats. Rats were allocated into five groups: naïve, HPC, and three hesperidin treated (50, 100, and 200 mg/kg/d; orally) for 4 consecutive days per week for 16 weeks. Liver tissues and blood samples were collected for histopathological, immunohistochemical, and transmission electron microscope examinations, liver function, alfa-fetoprotein level, and isolation of exosomal and autophagy RNAs. Hesperidin administration showed hepato-protective effects and improved the microscopic hepatic features with a decrease in glutathione S-transferase placental precancerous foci and the abundance of exosomes in liver tissues. Hesperidin improved liver function with a significant decrease in alfa-fetoprotein levels. Hesperidin dose-dependently decreased exosomal RAB11A messsenger RNA and long noncoding RNA-RP11-583F2.2 along with the increase in exosomal miR-1298, involved in the exophagy process. In conclusion, hesperidin likely suppresses liver carcinogenesis in rat model via the modulation of exosomal secretion and autophagy.

MicroRNA-125a-3p affects smooth muscle cell function in vascular stenosis

AIMS

Many studies have indicated that microRNAs are closely related to the process of peripheral arterial disease (PAD). Previously, we found that microRNA-125a-3p (miR-125a-3p) in restenotic arteries after interventional therapy of lower extremity vessels was notably decreased compared with that of normal control arteries. However, its role in the development of vascular stenosis is not yet clearly understood. The purpose of this study was to investigate the expression, regulatory mechanism and function of miR-125a-3p in the process of vascular stenosis.

METHODS AND RESULTS

Quantitative reverse-transcription polymerase chain reaction assays indicated that miR-125a-3p in restenotic arteries after interventional therapy was significantly lower than that in normal control arteries. Immunofluorescence and in situ hybridization co-staining assays in arterial sections demonstrated that miR-125a-3p was mainly expressed in the medial smooth muscle layer. Transfection of miR-125a-3p mimics into cultured vascular smooth muscle cells (VSMCs) effectively inhibited cell proliferation and migration. Then, western blot and luciferase activity assays showed that recombinant human mitogen-activated protein kinase 1 (MAPK1) was a functional target of miR-125a-3p and was involved in miR-125a-3p-mediated cell effects. Finally, the lentiviral infection of miR-125a-3p in balloon-injured rat carotid vascular walls showed that miR-125a-3p overexpression significantly reduced the probability of neointimal membrane production.

CONCLUSIONS

miR-125a-3p can effectively inhibit the function of VSMCs and the occurrence of vascular stenosis by targeting MAPK1. This study introduces a new molecular mechanism of PAD. We show that regulation of the miR-125a-3p level has the potential to provide a new treatment for PAD and other proliferative vascular diseases.

Role of DNA Methylation in the Development and Differentiation of Intestinal Epithelial Cells and Smooth Muscle Cells

The mammalian intestine contains many different cell types but is comprised of 2 main cell types: epithelial cells and smooth muscle cells. Recent in vivo and in vitro evidence has revealed that various alterations to the DNA methylation apparatus within both of these cell types can result in a variety of cellular phenotypes including modified differentiation status, apoptosis, and uncontrolled growth. Methyl groups added to cytosines in regulatory genomic regions typically act to repress associated gene transcription. Aberrant DNA methylation patterns are often found in cells with abnormal growth/differentiation patterns, including those cells involved in burdensome intestinal pathologies including inflammatory bowel diseases and intestinal pseudo-obstructions. The altered methylation patterns being observed in various cell cultures and DNA methyltransferase knockout models indicate an influential connection between DNA methylation and gastrointestinal cells’ development and their response to environmental signaling. As these modified DNA methylation levels are found in a number of pathological gastrointestinal conditions, further investigations into uncovering the causative nature, and controlled regulation, of this epigenetic modification is of great interest.

Arterial Calcification Is Regulated Via an miR-204/DNMT3a Regulatory Circuit Both In Vitro and in Female Mice

Arterial calcification is a common cardiovascular disease that initiates from a process of osteoblastic differentiation of vascular smooth muscle cells (VSMCs). Accumulating evidence has demonstrated that microRNAs play an important role in regulating arterial calcification. miR-204 was significantly downregulated in calcified human renal arteries from patients with uremia; calcified arteries of mice, due to 5/6 nephrectomy with a high-phosphate diet (5/6 NTP); and in VSMCs induced by high phosphate concentration. The overexpression of miR-204 alleviated the osteoblastic differentiation of VSMCs. Bisulphite sequencing PCR revealed that CpG sites upstream of miR-204 DNA were hypermethylated in calcified VSMCs; in calcified arteries of mice, due to 5/6 NTP; and in calcified renal artery tissues from patients with uremia. Moreover, increased DNMT3a resulted in the hypermethylation of miR-204 in high phosphate concentration-induced VSMCs, whereas 5-aza-2'-deoxycytidine could restore the expression of miR-204 in high phosphate concentration-induced VSMCs. Moreover, we found that DNMT3a was the target of miR-204, and the methylation ratio of miR-204 was decreased significantly, meaning that the expression of miR-204 was restored when DNMT3a was knocked down by using DNMT3a small interfering RNA, resulting in abrogation of the effect of high phosphate concentration on VSMC calcification. The progress of arterial calcification is regulated by the miR-204/DNMT3a regulatory circuit.

The role of infiltrating immune cells in dysfunctional adipose tissue

Adipose tissue (AT) dysfunction, characterized by loss of its homeostatic functions, is a hallmark of non-communicable diseases. It is characterized by chronic low-grade inflammation and is observed in obesity, metabolic disorders such as insulin resistance and diabetes. While classically it has been identified by increased cytokine or chemokine expression, such as increased MCP-1, RANTES, IL-6, interferon (IFN) gamma or TNFα, mechanistically, immune cell infiltration is a prominent feature of the dysfunctional AT. These immune cells include M1 and M2 macrophages, effector and memory T cells, IL-10 producing FoxP3+ T regulatory cells, natural killer and NKT cells and granulocytes. Immune composition varies, depending on the stage and the type of pathology. Infiltrating immune cells not only produce cytokines but also metalloproteinases, reactive oxygen species, and chemokines that participate in tissue remodelling, cell signalling, and regulation of immunity. The presence of inflammatory cells in AT affects adjacent tissues and organs. In blood vessels, perivascular AT inflammation leads to vascular remodelling, superoxide production, endothelial dysfunction with loss of nitric oxide (NO) bioavailability, contributing to vascular disease, atherosclerosis, and plaque instability. Dysfunctional AT also releases adipokines such as leptin, resistin, and visfatin that promote metabolic dysfunction, alter systemic homeostasis, sympathetic outflow, glucose handling, and insulin sensitivity. Anti-inflammatory and protective adiponectin is reduced. AT may also serve as an important reservoir and possible site of activation in autoimmune-mediated and inflammatory diseases. Thus, reciprocal regulation between immune cell infiltration and AT dysfunction is a promising future therapeutic target.

No detectable differential microRNA expression between non-atherosclerotic arteries of type 2 diabetic patients (treated or untreated with metformin) and non-diabetic patients

Background

Type 2 diabetes mellitus (T2DM) is an independent risk factor of cardiovascular disease (CVD), however, the underlying mechanisms are largely unknown. Using non-atherosclerotic internal thoracic arteries (ITAs) obtained from coronary artery bypass grafting, we previously identified a distinct elevation in the level of proteins comprising the arterial basement membrane in T2DM patients not treated with metformin. Altered transcription of genes encoding these proteins has not been observed, indicating alternative mechanisms of dysregulation.

Methods

In this study we screened for differential expression of arterial microRNAs (miRNAs) in T2DM patients to test the hypothesis that the arterial protein signature of diabetic patients is associated with dysregulation at the miRNA level, and further to lay the foundation for novel hypotheses addressing the increased CVD risk of T2DM patients. MiRNA isolated from fresh frozen ITAs [from 18 T2DM- (10 of which were subject to metformin treatment) and 30 non-diabetes mellitus (non-DM) patients] were analyzed by microarray, and miRNAs isolated from formalin-fixated paraffin-embedded (FFPE) ITAs were analyzed by quantitative PCR (qPCR) in an independent study group [26 T2DM- (15 of which were subject to metformin treatment) and 26 non-DM patients] to determine expression levels of miRNAs in a pre-defined panel of 12 miRNAs.

Results

Unexpectedly, no miRNAs were found to be affected by T2DM status in either of the two study groups.

Conclusions

Our data suggest that alternatives to microRNA dysregulation underlie T2DM-associated protein changes in non-atherosclerotic arteries.

Electronic supplementary material

The online version of this article (10.1186/s12933-018-0715-y) contains supplementary material, which is available to authorized users.

MiR-140-3p is Involved in In-Stent Restenosis by Targeting C-Myb and BCL-2 in Peripheral Artery Disease

Aim: In-Stent Restenosis (ISR) is the major reason for recurrent ischemia and amputation after endovascular treatment of Peripheral Artery Disease (PAD). Our previous study demonstrated that miR-140-3p is significantly down-regulated in PAD arteries. However, expression and function of miR-140-3p in ISR of human PAD are currently unclear.

The aim of this study is to determine the miR-140-3p expression and its regulative role in ISR of PAD.

Methods: The RNA level was determined by quantitative real-time polymerase chain Reaction (qRT-PCR) and in situ hybridization. Primary cultured ASMCs were isolated from human femoral arterial of the healthy donors or ISR patients. Cell proliferation was determined by Edu incorporation and CCK-8 assay. Apoptosis was determined by Annexin-V/PI Double-Staining assay and TUNEL assay. A rat carotid artery balloon angioplasty model was used to investigate the effect of miR-140-3p on restenosis.

Results: MiR-140-3p was significantly down-regulated in PAD and ISR arteries than normal arteries. Primary cultured ISR ASMCs exhibited elevated proliferation and down-regulated miR-140-3p than normal ASMCs. Transfection of miR-140-3p mimic attenuated PDGF-BB-induced proliferation in cultured ASMCs and induced apoptosis. Luciferase reporter assay indicated that miR-140-3p transfection significantly down-regulated C-Myb and BCL-2 in ISR ASMCs by targeting to their 3′-UTRs. MiR-140-3p transfection induced anti-proliferation and apoptosis in ASMCs, which were ameliorated by over-expression of C-Myb or BCL-2. Moreover, the animal study showed that miR-140-3p can reduce restenosis following angioplasty via targeting C-Myb and BCL-2.

Conclusions: The result suggests that miR-140-3p regulates ASMC function via targeting C-Myb and BCL-2 in the process of ISR in PAD. The novel findings may offer a hopeful therapeutic target for human PAD.

Micro RNA-1298 opposes the effects of chronic oxidative stress on human trabecular meshwork cells via targeting on EIF4E3

OBJECTIVE

This study aimed to investigate the effect and potential mechanism of miR-1298 in the progression of human trabecular meshwork (HTM) cells.

MATERIAL AND METHODS

Expression of miR-1298 was assessed by quantitative real time PCR (qRT-PCR), as well as in HTM-1 and HTM-2 cells. Mature miR-1298 mimic, miR-1298 inhibitor, and si-EIF4E3 and their corresponding controls were transfected into HTM-1 and HTM-2 to obtain stable HTM cells. Luciferase reporter assay was used to verify regulation between miR-1298 and EIF4E3. Cytotoxicity and Oxidative damage were assessed using commercial kits, and apoptosis was determined using flow cytometry. ECM and apoptosis related factors were determined using qRT-PCR and western blotting, as well as the pathway related factors.

RESULTS

The expression of miR-1298 was significantly decreased both in glaucoma and HTM cells. MiR-1298 mimic could significantly inhibit the increase of cytotoxicity, apoptosis, accumulation of carbonylated proteins and ECM induced by COS, but miR-1298 inhibitor could obviously promote the increase effects caused by COS in HTM cells. EIF4E3 was a downstream target of miR-1298. Sliced EIF4E3 could significantly inhibit the increase effects induced miR-1298 inhibitor in HTM cells under COS. The expression levels of TGF-β2 and Smad4 were significantly increased, and Wnt3a and β-cantenin were obviously decreased under COS, and miR-1298 inhibitor could markedly promote this increase effect, while sliced EIF4E3 could reverse the effect of miR-1298 under COS.

CONCLUSIONS

miR-1298 could protect HTM cells to against damage caused by COS via inhibiting TGF-β2/Smad4 pathway and activating canonical Wnt pathway.

Genome-wide miRNA response to anacardic acid in breast cancer cells

MicroRNAs are biomarkers and potential therapeutic targets for breast cancer. Anacardic acid (AnAc) is a dietary phenolic lipid that inhibits both MCF-7 estrogen receptor α (ERα) positive and MDA-MB-231 triple negative breast cancer (TNBC) cell proliferation with IC50s of 13.5 and 35 μM, respectively. To identify potential mediators of AnAc action in breast cancer, we profiled the genome-wide microRNA transcriptome (microRNAome) in these two cell lines altered by the AnAc 24:1n5 congener. Whole genome expression profiling (RNA-seq) and subsequent network analysis in MetaCore Gene Ontology (GO) algorithm was used to characterize the biological pathways altered by AnAc. In MCF-7 cells, 69 AnAc-responsive miRNAs were identified, e.g., increased let-7a and reduced miR-584. Fewer, i.e., 37 AnAc-responsive miRNAs were identified in MDA-MB-231 cells, e.g., decreased miR-23b and increased miR-1257. Only two miRNAs were increased by AnAc in both cell lines: miR-612 and miR-20b; however, opposite miRNA arm preference was noted: miR-20b-3p and miR-20b-5p were upregulated in MCF-7 and MDA-MB-231, respectively. miR-20b-5p target EFNB2 transcript levels were reduced by AnAc in MDA-MB-231 cells. AnAc reduced miR-378g that targets VIM (vimentin) and VIM mRNA transcript expression was increased in AnAc-treated MCF-7 cells, suggesting a reciprocal relationship. The top three enriched GO terms for AnAc-treated MCF-7 cells were B cell receptor signaling pathway and ribosomal large subunit biogenesis and S-adenosylmethionine metabolic process for AnAc-treated MDA-MB-231 cells. The pathways modulated by these AnAc-regulated miRNAs suggest that key nodal molecules, e.g., Cyclin D1, MYC, c-FOS, PPARγ, and SIN3, are targets of AnAc activity.

MiR-1298 affects cell proliferation and apoptosis in C6 cells by targeting SET domain containing 7

Our previous high-throughput sequencing indicated that rno-miR-1298 was down-regulated in ischemia-reperfusion model of rat. However, little is known about the function and molecular mechanism of rno-miR-1298 in rat tumor cell. In this study, rno-miR-1298 was detected to be significantly down-regulated in rat tumor C6 cells. Moreover, overexpression of rno-miR-1298 obviously inhibited the proliferation and induced apoptosis in C6 cells. SET domain containing 7 (SETD 7) was identified to be a target of rno-miR-1298 using bioinformatics and luciferase reporter assays. Overexpression of rno-miR-1298 markedly reduced the expression of SETD 7 at protein level. Knockdown of SETD 7 also suppressed proliferation and promoted apoptosis in C6 cells. It was indicated that rno-miR-1298 affected cell proliferation and apoptosis of rat tumor cells by targeting SETD 7. Thus, the newly identified miR-1298/SETD 7 expands the elaboration of the mechanisms of the development and progression of tumors and may provide therapeutic target for tumors of nervous system.

Roles of miR‑4463 in H2O2‑induced oxidative stress in human umbilical vein endothelial cells

Oxidative stress is implicated in the pathophysiology of vascular diseases, including atherosclerosis, aneurysm and arteriovenous fistula. A previous study from our lab suggested that microRNA (miR)-4463 may be involved in the pathogenesis of vascular disease; however, the roles of oxidative stress in the molecular mechanisms underlying the actions of miR-4463 in vascular disease have yet to be elucidated. The aim of the present study was to investigate the role of miR-4463 in hydrogen peroxide (H₂O₂)-induced oxidative stress in human umbilical vein endothelial cells (HUVECs). Reverse transcription-quantitative polymerase chain reaction was used to assess the expression levels of miR-4463 in HUVECs treated with various concentrations of H₂O₂. Flow cytometry was used to evaluate the percentage of apoptotic cells, and the protein expression levels of the apoptotic markers cleaved (C)-caspase3, poly (adenosine diphosphate-ribose) polymerase 1 (PARP1), B cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax) and X-linked inhibitor of apoptosis protein (XIAP) were determined using western blot analysis. The results demonstrated that the apoptotic rate of HUVECs was increased following treatment with H₂O₂ in a concentration-dependent manner, and the expression of miR-4463 was also upregulated in a dose-dependent manner. Following transfection with miR-4463 mimics, the levels of malondialdehyde and reactive oxygen species were increased in HUVECs, with a corresponding increase in the apoptotic rate. Furthermore, western blot analysis revealed that the protein expression levels of C-caspase3, PARP1 and Bax were upregulated, whereas the levels of Bcl-2 and XIAP were downregulated. In conclusion, the present findings suggested that the upregulation of miR-4463 may enhance H₂O₂-induced oxidative stress and promote apoptosis in HUVECs in vitro.

Demethylation of the MIR145 promoter suppresses migration and invasion in breast cancer

miR-145 has been implicated in the progression of breast cancer. Here, we report that its expression is decreased in breast cancer specimens and cell lines and that this low level of expression is associated with DNA methylation of its gene, MIR145. Methylation of MIR145 has previously been correlated with cell migration and invasion, both in vivo and in vitro. We found that demethylation of MIR145 reactivates miR-145 and contributes to the anti-cancer properties of 5-aza-2'-deoxyazacytidine (5-AzaC). Therefore, miR-145 is a potentially valuable biomarker for breast cancer.

Nicotine facilitates VSMC dysfunction through a miR-200b/RhoGDIA/cytoskeleton module

Nicotine can induce the abnormal migration and proliferation of vascular smooth muscle cells (VSMCs). We have previously shown that cytoskeletal proteins and RhoGDIA, a negative regulator of the Rho GTPase pathway, are involved in the nicotine-induced dysfunction of VSMCs. Here, we found that nicotine can activate the Rho GTPase pathway and induce the synthesis of the cytoskeletal proteins in VSMCs through the activation of intracellular downstream signaling pathways, including targets such as MYPT1, PAK1 and PI3K/AKT. Upon nicotine treatment, the mRNA level of RhoGDIA is increased but protein level is decreased both in vitro and in vivo, which suggested a mechanism of post-translational regulation. By the dual luciferase reporter assay, we identified the microRNA-200b (miR-200b) as a modulator of the behavioural changes of VSMCs in response to nicotine through targeting RhoGDIA directly. Introducing miR-200b inhibitors into cultured VSMCs significantly attenuated cell proliferation and migration. Additionally, we found that hypomethylation in the CpG island shore region of miR-200b was responsible for the nicotine-induced miR-200b up-regulation in VSMCs. The study demonstrates that nicotine facilitates VSMC dysfunction through a miR-200b/RhoGDIA/cytoskeleton module through the hypomethylation of miR-200b promoter and suggests that epigenetic modifications may play an important role in the pathological progression.

Roles of bta-miR-29b promoter regions DNA methylation in regulating miR-29b expression and bovine viral diarrhea virus NADL replication in MDBK cells

MicroRNAs (miRNAs) are an important class of small, non-coding RNAs that control target genes expression by degradation of target mRNAs or by inhibiting protein translation in many biological processes and cellular pathways. In a previous study, we found that miR-29b interfered with bovine viral diarrhea virus (BVDV) replication. However, the mechanisms of regulation of miR-29b expression are not well known. DNA methylation is an important epigenetic mechanism for silencing gene transcription, and plays an important role in promoter choice, protein expression, and regulation of miRNAs expression. In this study, we focused on the roles of DNA methylation of miR-29b promoter in regulating miR-29b expression and investigated the effects of DNA (cytosine-5) methyltransferase 1 (DNMT1) knockdown on miR-29b expression and BVDV (strain NADL) replication. Our results showed that methylation levels of miR-29b promoter were significantly decreased in BVDV NADL-infected MDBK cells. Furthermore, DNMT1 silencing significantly decreased the methylation levels of miR-29b promoter, up-regulated miR-29b expression and inhibited BVDV NADL replication, which supports the important roles of DNA methylation in regulating miRNA expression and further proves an evidence for our previous views.

From Nutrient to MicroRNA: a Novel Insight into Cell Signaling Involved in Skeletal Muscle Development and Disease

Skeletal muscle is a remarkably complicated organ comprising many different cell types, and it plays an important role in lifelong metabolic health. Nutrients, as an external regulator, potently regulate skeletal muscle development through various internal regulatory factors, such as mammalian target of rapamycin (mTOR) and microRNAs (miRNAs). As a nutrient sensor, mTOR, integrates nutrient availability to regulate myogenesis and directly or indirectly influences microRNA expression. MiRNAs, a class of small non-coding RNAs mediating gene silencing, are implicated in myogenesis and muscle-related diseases. Meanwhile, growing evidence has emerged supporting the notion that the expression of myogenic miRNAs could be regulated by nutrients in an epigenetic mechanism. Therefore, this review presents a novel insight into the cell signaling network underlying nutrient-mTOR-miRNA pathway regulation of skeletal myogenesis and summarizes the epigenetic modifications in myogenic differentiation, which will provide valuable information for potential therapeutic intervention.

Epigenetics and Peripheral Artery Disease

The term epigenetics is usually used to describe inheritable changes in gene function which do not involve changes in the DNA sequence. These typically include non-coding RNAs, DNA methylation and histone modifications. Smoking and older age are recognised risk factors for peripheral artery diseases, such as occlusive lower limb artery disease and abdominal aortic aneurysm, and have been implicated in promoting epigenetic changes. This brief review describes studies that have associated epigenetic factors with peripheral artery diseases and investigations which have examined the effect of epigenetic modifications on the outcome of peripheral artery diseases in mouse models. Investigations have largely focused on microRNAs and have identified a number of circulating microRNAs associated with human peripheral artery diseases. Upregulating or antagonising a number of microRNAs has also been reported to limit aortic aneurysm development and hind limb ischemia in mouse models. The importance of DNA methylation and histone modifications in peripheral artery disease has been relatively little studied. Whether circulating microRNAs can be used to assist identification of patients with peripheral artery diseases and be modified in order to improve the outcome of peripheral artery disease will require further investigation.

MicroRNA-140 is elevated and mitofusin-1 is downregulated in the right ventricle of the Sugen5416/hypoxia/normoxia model of pulmonary arterial hypertension

Heart failure, a major cause of morbidity and mortality in patients with pulmonary arterial hypertension (PAH), is an outcome of complex biochemical processes. In this study, we determined changes in microRNAs (miRs) in the right and left ventricles of normal and PAH rats. Using an unbiased quantitative miR microarray analysis, we found 1) miR-21-5p, miR-31-5 and 3p, miR-140-5 and 3p, miR-208b-3p, miR-221-3p, miR-222-3p, miR-702-3p, and miR-1298 were upregulated (>2-fold; P < 0.05) in the right ventricle (RV) of PAH compared with normal rats; 2) miR-31-5 and 3p, and miR-208b-3p were upregulated (>2-fold; P < 0.05) in the left ventricle plus septum (LV+S) of PAH compared with normal rats; 3) miR-187-5p, miR-208a-3p, and miR-877 were downregulated (>2-fold; P < 0.05) in the RV of PAH compared with normal rats; and 4) no miRs were up- or downregulated with >2-fold in LV+S compared with RV of PAH and normal. Upregulation of miR-140 and miR-31 in the hypertrophic RV was further confirmed by quantitative PCR. Interestingly, compared with control rats, expression of mitofusin-1 (MFN1), a mitochondrial fusion protein that regulates apoptosis, and which is a direct target of miR-140, was reduced in the RV relative to LV+S of PAH rats. We found a correlation between increased miR-140 and decreased MFN1 expression in the hypertrophic RV. Our results also demonstrated that upregulation of miR-140 and downregulation of MFN1 correlated with increased RV systolic pressure and hypertrophy. These results suggest that miR-140 and MFN1 play a role in the pathogenesis of PAH-associated RV dysfunction.

Genetic and epigenetic alterations of microRNAs and implications for human cancers and other diseases

MicroRNAs (miRNAs) are a well-studied group of noncoding RNAs that control gene expression by interacting mainly with messenger RNA. It is known that miRNAs and their biogenesis regulatory machineries have crucial roles in multiple cell processes; thus, alterations in these genes often lead to disease, such as cancer. Disruption of these genes can occur through epigenetic and genetic alterations, resulting in aberrant expression of miRNAs and subsequently of their target genes. This review focuses on the disruption of miRNAs and their key regulatory machineries by genetic alterations, with emphasis on mutations and epigenetic changes in cancer and other diseases.

Regulation of connexin signaling by the epigenetic machinery

Connexins and their channels are involved in the control of all aspects of the cellular life cycle, ranging from cell growth to cell death, by mediating extracellular, intercellular and intracellular communication. These multifaceted aspects of connexin-related cellular signaling obviously require strict regulation. While connexin channel activity is mainly directed by posttranslational modifications, connexin expression as such is managed by classical cis/trans mechanisms. Over the past few years, it has become clear that connexin production is equally dictated by epigenetic actions. This paper provides an overview of the role of major determinants of the epigenome, including DNA methylation, histone acetylation and microRNA species, in connexin expression.

A Fleeting Glimpse Inside microRNA, Epigenetics, and Micropeptidomics

MicroRNAs (miRs) are important regulators of gene expression in numerous biological processes. Their maturation process is herein described, including the most updated insights from the current literature. Circa 2000 miR sequences have been identified in the human genome, with over 50,000 miR-target interactions, including enzymes involved in epigenetic modulation of gene expression. Moreover, some "pieces of RNA" previously annotated as noncoding have been recently found to encode micropeptides that carry out critical mechanistic functions in the cell. Advanced techniques now available will certainly allow a precise scanning of the genome looking for micropeptides hidden within the "noncoding" RNA.

microRNAs Distinctively Regulate Vascular Smooth Muscle and Endothelial Cells: Functional Implications in Angiogenesis, Atherosclerosis, and In-Stent Restenosis

Endothelial cells (EC) and vascular smooth muscle cells (VSMC) are the main cell types within the vasculature. We describe here how microRNAs (miRs)--noncoding RNAs that can regulate gene expression via translational repression and/or post-transcriptional degradation--distinctively modulate EC and VSMC function in physiology and disease. In particular, the specific roles of miR-126 and miR-143/145, master regulators of EC and VSMC function, respectively, are deeply explored. We also describe the mechanistic role of miRs in the regulation of the pathophysiology of key cardiovascular processes including angiogenesis, atherosclerosis, and in-stent restenosis post-angioplasty. Drawbacks of currently available therapeutic options are discussed, pointing at the challenges and potential clinical opportunities provided by miR-based treatments.