Downregulation of miR-151-5p contributes to increased susceptibility to arrhythmogenesis during myocardial infarction with estrogen deprivation

Protective effect of propolis on myocardial ischemia/reperfusion injury in males and ovariectomized females but not in intact females

The aim of this study is to investigate the effect of propolis, which may have estrogenic effects, on myocardial ischemia/reperfusion (mI/R) injury not only in male rats but also in intact and ovariectomized (ovx) female rats. Six groups were formed: untreated males (n = 8), treated males (n = 9), untreated intact females (n = 9), treated intact females (n = 10), untreated ovx females (n = 10), and treated ovx females (n = 8). An alcoholic extract of a single dose of propolis (200 mg/kg) was administered orally daily for 14 days. Thirty minutes of ischemia and 120 min of reperfusion were performed. Blood pressure, heart rate, arrhythmias (ventricular premature contraction [VPC], ventricular tachycardia [VT], ventricular fibrillation [VF]), and myocardial infarct size were evaluated. Total antioxidant status (TAS), total oxidant status (TOS), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and 17 beta-estradiol (E2) were measured. The untreated females showed more resistance to mI/R injury than the untreated males, as evidenced by lower duration, incidence, and score of arrhythmias, and smaller infarct size (p < .05). After ovx, this resistance disappeared. Propolis improved these values in treated males and treated ovx females (p < .05). Propolis increased TAS in treated males and decreased TOS in treated ovx females as well as elevated SOD in all treated groups (p < .05). Propolis decreased E2 level in treated intact females; however, it increased E2 level in treated ovx females (p < .05). The results revealed that propolis could protect the heart against mI/R injury in males and ovx females. PRACTICAL APPLICATIONS: It is known that the female heart has an increased sensitivity to myocardial ischemia/reperfusion (mI/R) injury due to estrogen deficiency and/or estrogen deprivation following menopause or surgical removal of the ovaries. Propolis has the potential to mimic estrogen under physiological and pathophysiological conditions, as well as its antioxidant property. The results indicated that propolis decreased myocardial infarct size, arrhythmia score, arrhythmia duration, and incidence in ovariectomized female rats and male rats. In addition, the present results demonstrated that an alcoholic extract of propolis as a natural product can effectively maintain the resistance of female heart to mI/R injury after estrogen deficiency.

Cerebrovascular microRNA Expression Profile During Early Development of Alzheimer's Disease in a Mouse Model

BACKGROUND

Emerging evidence demonstrates association of Alzheimer's disease (AD) with impaired delivery of blood oxygen and nutrients to and throughout the brain. The cerebral circulation plays multiple roles underscoring optimal brain perfusion and cognition entailing moment-to-moment blood flow control, vascular permeability, and angiogenesis. With currently no effective treatment to prevent or delay the progression of AD, cerebrovascular microRNA (miRNA) markers corresponding to post-transcriptional regulation may distinguish phases of AD.

OBJECTIVE

We tested the hypothesis that cerebrovascular miRNA expression profiles indicate developmental stages of AD pathology.

METHODS

Total RNA was isolated from total brain vessel segments of male and female 3xTg-AD mice [young, 1-2 mo; cognitive impairment (CI), 4-5 mo; extracellular amyloid-β plaques (Aβ), 6-8 mo; plaques+neurofibrillary tangles (AβT), 12-15 mo]. NanoString technology nCounter miRNA Expression panel for mouse was used to screen for 599 miRNAs.

RESULTS

Significant (p < 0.05) downregulation of various miRNAs indicated transitions from young to CI (e.g., let-7g & miR-1944, males; miR-133a & miR-2140, females) and CI to Aβ (e.g., miR-99a, males) but not from Aβ to AβT. In addition, altered expression of select miRNAs from overall Pre-AD (young + CI) versus AD (Aβ+ AβT) were detected in both males (let-7d, let-7i, miR-23a, miR-34b-3p, miR-99a, miR-126-3p, miR-132, miR-150, miR-151-5p, miR-181a) and females (miR-150, miR-539). Altogether, at least 20 cerebrovascular miRNAs effectively delineate AD versus Pre-AD pathology.

CONCLUSION

Using the 3xTg-AD mouse model, these data demonstrate that cerebrovascular miRNAs pertaining to endothelial function, vascular permeability, angiogenesis, inflammation, and Aβ/tau metabolism can track early development of AD.

miR-151 Affects Low-Temperature Tolerance of Penaeus vannamei by Modulating Autophagy Under Low-Temperature Stress

MicroRNAs (miRNAs) play key roles in many physiologic and pathologic processes, including autophagy. Autophagy is cellular in an emergency response mechanism of environment stress, but their complex molecular regulatory mechanism under low-temperature stress is largely unknown in shrimp, especially miRNA-mediated regulation of autophagy in low-temperature tolerance. In this article, a shrimp PvTOR and miRNA pva-miR-151 cooperation in response to low-temperature stress has been reported. Pva-miR-151 showed expression patterns opposite to target PvTOR under low-temperature stress. The pva-miR-151 targets the 3'-UTR region of PvTOR, regulate the formation of autophagosome, which contribute to the degradation and recycling of damaged organelles. In addition, the low-temperature tolerance was correlated positively with autophagy in shrimp. Silenced pva-miR-151 increased sensitivity to low-temperature stress, whereas overexpression pva-miR-151 decreased the expression of PvTOR and p-TOR and increased tolerance to low-temperature stress by improving the formation of autophagosome and total hemocyte count. In addition, the TOR activator 3BDO can partially rescue autophagy induced by overexpression of pva-miR-151; these results indicate that miR-151 was necessary for the low-temperature tolerance in shrimp. Taken together, we provide a novel strategy and mechanism for shrimp breeding to improve shrimp low-temperature tolerance.

Expression Profile of Circulating MicroRNAs in Dogs With Cardiac Hypertrophy: A Pilot Study

This study aimed to identify the expression profile of circulating microRNAs in dogs with eccentric or concentric cardiac hypertrophy. A total of 291 microRNAs in serum samples of five dogs with myxomatous mitral valve degeneration (MMVD) and five dogs with pulmonic stenosis (PS) were compared with those of five healthy dogs using microarray analysis. Results of microarray analysis revealed up-regulation of cfa-miR-130b [fold change (FC) = 2.13, p = 0.014), down-regulation of cfa-miR-375 (FC = 1.51, p = 0.014), cfa-miR-425 (FC = 2.56, p = 0.045), cfa-miR-30d (FC = 3.02, p = 0.047), cfa-miR-151 (FC = 1.89, p = 0.023), cfa-miR-19b (FC = 3.01, p = 0.008), and cfa-let-7g (FC = 2.53, p = 0.015) in MMVD group which showed eccentric cardiac hypertrophy, up-regulation of cfa-miR-346 (FC = 2.74, p = 0.032), down-regulation of cfa-miR-505 (FC = 1.56, p = 0.016) in PS group which showed concentric cardiac hypertrophy, and down-regulation of cfa-miR-30c (FC = 3.45, p = 0.013 in MMVD group; FC = 3.31, p = 0.014 in PS group) and cfa-let-7b (FC = 11.42, p = 0.049 in MMVD group; FC = 5.88, p = 0.01 in PS group) in both MMVD and PS groups. In addition, the unsupervised hierarchical clustering of differentially expressed microRNAs in each group resulted in complete separation of healthy dogs from dogs with heart diseases. Therefore, eleven microRNAs among 291 microRNAs were identified as differentially expressed circulating microRNAs related to MMVD or PS in dogs. This pilot study demonstrates that the microRNAs identified in this study could be possible candidates for novel biomarker or therapeutic target related to cardiac hypertrophy in dogs.

MiR-151a-3p Promotes Postmenopausal Osteoporosis by Targeting SOCS5 and Activating JAK2/STAT3 Signaling

Postmenopausal osteoporosis, the most common type of primary osteoporosis, poses a significant threat to women's health worldwide. However, detailed molecular mechanism and therapeutic strategy for postmenopausal osteoporosis remain insufficient. Increasing evidence suggests that microRNAs contributed to the pathogenesis of osteoporosis and could be considered as potential therapeutic targets. In this study, we found that miR-151a-3p was upregulated in osteoporosis samples. Experiments in MC3T3-E1 cells indicated that miR-151a-3p significantly inhibited cell viability and promoted lactate dehydrogenase release, as well as increased RANKL/OPG ratio and decreased Runx2 and BMP2 expressions. SOCS5 was identified as a direct target gene of miR-151a-3p, which was confirmed by luciferase reporter assay. Moreover, an inverse correlation between miR-151a-3p and SOCS5 was observed in osteoporosis femurs. In addition, JAK2/STAT3 pathway was found to be involved in the progress of osteoporosis mediated by miR-151a-3p-SOCS5 axis. In vivo, ovariectomized (OVX) rat model was established to simulate postmenopausal osteoporosis. The results revealed that miR-151a-3p significantly decreased the bone mineral density and biomechanical parameters of femurs in OVX rats by targeting SOCS5, and that JAK2/STAT3 pathway is a downstream target of miR-151a-3p-SOCS5 axis in OVX rats. In conclusion, our findings suggested that miR-151a-3p contributed to the pathogenesis of postmenopausal osteoporosis, and promoted its progress by targeting SOCS5 and activating JAK2/STAT3 signaling. Thus, anti-miR-151a-3p could be a potential therapeutic strategy for postmenopausal osteoporosis.

Non-genomic Effects of Estrogen on Cell Homeostasis and Remodeling With Special Focus on Cardiac Ischemia/Reperfusion Injury

This review takes into consideration the main mechanisms involved in cellular remodeling following an ischemic injury, with special focus on the possible role played by non-genomic estrogen effects. Sex differences have also been considered. In fact, cardiac ischemic events induce damage to different cellular components of the heart, such as cardiomyocytes, vascular cells, endothelial cells, and cardiac fibroblasts. The ability of the cardiovascular system to counteract an ischemic insult is orchestrated by these cell types and is carried out thanks to a number of complex molecular pathways, including genomic (slow) or non-genomic (fast) effects of estrogen. These pathways are probably responsible for differences observed between the two sexes. Literature suggests that male and female hearts, and, more in general, cardiovascular system cells, show significant differences in many parameters under both physiological and pathological conditions. In particular, many experimental studies dealing with sex differences in the cardiovascular system suggest a higher ability of females to respond to environmental insults in comparison with males. For instance, as cells from females are more effective in counteracting the ischemia/reperfusion injury if compared with males, a role for estrogen in this sex disparity has been hypothesized. However, the possible involvement of estrogen-dependent non-genomic effects on the cardiovascular system is still under debate. Further experimental studies, including sex-specific studies, are needed in order to shed further light on this matter.

Next generation MicroRNA sequencing to identify coronary artery disease patients at risk of recurrent myocardial infarction

BACKGROUND AND AIMS

Variation in micro-RNA (miRNA) levels in blood has been associated with alterations of physiological functions of the cardiovascular system. Circulating miRNA have the potential to become reliable biomarkers for risk stratification and early detection of cardiovascular events. Recurrent thrombotic events in patients with established coronary artery disease (CAD) demonstrate the need for personalized approaches to secondary prevention, especially in light of recent novel treatment approaches.

METHODS

In a single center cohort study, whole blood samples were collected from 437 subjects undergoing cardiac catheterization, who were followed for recurrent cardiovascular events during a mean follow up of 1.5 years. We selected a case cohort (n = 22) with recurrent thrombotic events on standard medical therapy (stent thrombosis (n = 6) or spontaneous myocardial infarction (MI) (n = 16)) and a matched cohort with CAD, but uneventful clinical follow up (n = 26), as well as a control group with cardiovascular risk factors, but without angiographic CAD (n = 24). We performed complete miRNA next generation sequencing of RNA extracted from whole blood samples (including leukocytes and platelets).

RESULTS

A differential pattern of miRNA expression was found among controls, CAD patients with no events, and CAD patients with recurrent events. MiRNA previously associated with MI, CAD, endothelial function, vascular smooth muscle cells, platelets, angiogenesis, heart failure, cardiac hypertrophy, arrhythmia, and stroke were found variably expressed in our case-control cohorts. Seventy miRNA (FDR <0.05) were linked to the risk of recurrent myocardial infarction and future stent thrombosis, as compared to CAD patients with subsequently uneventful follow up.

CONCLUSIONS

MiRNA next generation sequencing demonstrates altered fingerprint profile of whole blood miRNA expression among subjects with subsequent recurrent thrombotic events on standard medical therapy ('non-responders'), as compared to subjects with no recurrent cardiovascular events. MiRNA profiling may be useful to identify high risk subjects and provide additional insights into disease mechanisms not currently attenuated with standard medical therapy used in CAD treatment.

miR-30a attenuates cardiac fibrosis in rats with myocardial infarction by inhibiting CTGF

The mechanism of miR-30a in myocardial fibrosis in rats with myocardial infarction (MI) was investigated. rAAV9-miR-30a was constructed and transfected to heart via injecting into the left ventricular cavity of MI rats. The sham operation group, control group, miR-30a group and miR-30a-NC group were established. Besides, the 3′-UTR of CTGF was inserted into luciferase expression plasmid (pMir-report), then transfected into COS1 cells. miR-30a and control miRNA were, respectively, cotransfected into COS1 cells. The expression of luciferase was detected before and after knockdown of the binding site of miR-30a and the 3′-UTR of CTGF. Four weeks after MI surgery, cardiac function was measured by color Doppler echocardiography, including short axis shortening (FS) and left ventricular ejection fraction (LVEF); the myocardial collagen volume fraction (CVF) was observed by Masson's staining; deposition of collagen I and collagen III were evaluated by immunohistochemical stain; using real-time PCR to detect expression levels of miR-30a and CTGF; the expression of CTGF was observed by western blotting. In MI group, cardiac function was significantly improved, while the expression levels of CVF, collagen I and III, the ratio of type I/III collagen, CTGF were significantly reduced. After knockdown the binding site of miR-30a and the 3′-UTR of CTGF, luciferase expression in COS1 cells decreased significantly. miR-30a might inhibit the expression of CTGF by directly combining with the 3′-UTR site of CTGF after MI, thereby reduce the production of collagen in myocardia, inhibit myocardial fibrosis, then improve cardiac function.

Chronic hyperinsulinemia induced miR-27b is linked to adipocyte insulin resistance by targeting insulin receptor

Defect in insulin signaling leads to the development of insulin resistance followed by type 2 diabetes. Exploiting our previously developed physiological chronic hyperinsulinemia (CI)-mediated insulin resistance (IR) model, we wanted to understand how miRNAs contribute to the development of IR. Amongst the identified and validate miRNAs, the expression of miR-27b was found to be highly upregulated during CI-induced IR in 3T3-L1 adipocytes. We also validated the expression of miR-27b in CI-induced IR in human mesenchymal stem cell (hMSC)-derived adipocytes and in vivo high fat diet (HFD)-induced IR mice model. Bioinformatics target prediction softwares and luciferase reporter assay identified insulin receptor (INSR) as one of a prime target of miR-27b. Lentiviral mediated overexpression of miR-27b impairs insulin signaling by modulating INSR expression that in turn led to decreased glucose uptake in both 3T3-L1 and hMSC-derived adipocytes. Conversely, inhibition of miR-27b reversed CI-mediated suppression of target protein INSR and improved phosphorylation of Akt, a nodal protein of insulin signaling that is impaired by CI treatment. Lentiviral mediated overexpression of miR-27b in in vivo C57BL/6 mice impaired whole body glucose tolerance and adipose tissue insulin sensitivity. Furthermore, inhibition of miR-27b in HFD-induced insulin resistance mice model improved glucose tolerance and adipose tissue insulin sensitivity by increasing the expression of its target gene INSR in eWAT. Thus, our results indicate that miR-27b functions as a prime modulator of CI-induced IR via regulating the expression of INSR. KEY MESSAGES: miR-27b is upregulated in different in vitro and in vivo models of insulin resistance. miR-27b directly suppresses the expression of INSR by targeting 3'UTR of INSR. Modulation of miR-27b expression regulates insulin sensitivity by targeting INSR.

Analysis of Circulating miR-1, miR-23a, and miR-26a in Atrial Fibrillation Patients Undergoing Coronary Bypass Artery Grafting Surgery

Atrial fibrillation (AF) is the most common arrhythmia after cardiac surgery. From a pathophysiological point of view, a myriad of factors such as trauma, atrial dilation, ischemia, mechanical myopericarditis, autonomic imbalance, loss of connexins, AF nest remodeling, inflammation, sutures, and dysfunction caused by postextracorporeal circulation can contribute to postoperative atrial fibrillation (POAF) resulting in a longer hospital stay and consequently higher cost. Recent studies showed that short fragments of RNA, called microRNA (miRNA), can contribute to the development of several cardiovascular diseases, including AF. The aim of this study was to evaluate the levels of circulating miRNAs (miR-1, -23a, and -26a) that can be involved in POAF. Patients submitted to coronary artery bypass graft surgery were grouped in POAF (24 patients) and without POAF (24 patients). Results showed older age, longer clamp-time, and more days in the intensive care unit as well as a longer total hospital stay in the POAF group. Preoperative levels of circulating miRNAs were similar. Analysis of miRNAs revealed significantly lower circulating levels of miRNA-23a (P  =  0.02) and -26a (P  =  0.01) in the POAF group during the postoperative period. Receiver operating characteristic (ROC) analysis showed the area under the ROC curve of miR-23a and miR-26a for predicting FA was 0.63 (95% confidence interval [CI]: 0.51-0.74; P  =  0.02) and 0.66 (95% CI: 0.55-0.77; P  =  0.01), respectively. Our data suggests that circulating miRNA-23a and -26a may be involved in the underlying biology of postoperative AF development.

Over-expression of microRNA-1 causes arrhythmia by disturbing intracellular trafficking system

Dysregulation of intracellular trafficking system plays a fundamental role in the progression of cardiovascular disease. Up-regulation of miR-1 contributes to arrhythmia, we sought to elucidate whether intracellular trafficking contributes to miR-1-driven arrhythmia. By performing microarray analyses of the transcriptome in the cardiomyocytes-specific over-expression of microRNA-1 (miR-1 Tg) mice and the WT mice, we found that these differentially expressed genes in miR-1 Tg mice were significantly enrichment with the trafficking-related biological processes, such as regulation of calcium ion transport. Also, the qRT-PCR and western blot results validated that Stx6, Braf, Ube3a, Mapk8ip3, Ap1s1, Ccz1 and Gja1, which are the trafficking-related genes, were significantly down-regulated in the miR-1 Tg mice. Moreover, we found that Stx6 was decreased in the heart of mice after myocardial infarction and in the hypoxic cardiomyocytes, and further confirmed that Stx6 is a target of miR-1. Meanwhile, knockdown of Stx6 in cardiomyocytes resulted in the impairments of PLM and L-type calcium channel, which leads to the increased resting ([Ca²⁺]_i). On the contrary, overexpression of Stx6 attenuated the impairments of miR-1 or hypoxia on PLM and L-type calcium channel. Thus, our studies reveals that trafficking-related gene Stx6 may regulate intracellular calcium and is involved in the occurrence of cardiac arrhythmia, which provides new insights in that miR-1 participates in arrhythmia by regulating the trafficking-related genes and pathway.

Blood pressure and expression of microRNAs in whole blood

Background

Blood pressure (BP) is a complex, multifactorial clinical outcome driven by genetic susceptibility, behavioral choices, and environmental factors. Many molecular mechanisms have been proposed for the pathophysiology of high BP even as its prevalence continues to grow worldwide, increasing morbidity and marking it as a major public health concern. To address this, we evaluated miRNA profiling in blood leukocytes as potential biomarkers of BP and BP-related risk factors.

Methods

The Beijing Truck Driver Air Pollution Study included 60 truck drivers and 60 office workers examined in 2008. On two days separated by 1–2 weeks, we examined three BP measures: systolic, diastolic, and mean arterial pressure measured at both pre- and post-work exams for blood NanoString nCounter miRNA profiles. We used covariate-adjusted linear mixed-effect models to examine associations between BP and increased miRNA expression in both pooled and risk factor-stratified analyses.

Results

Overall 43 miRNAs were associated with pre-work BP (FDR<0.05). In stratified analyses different but overlapping groups of miRNAs were associated with pre-work BP in truck drivers, high-BMI participants, and usual alcohol drinkers (FDR<0.05). Only four miRNAs were associated with post-work BP (FDR<0.05), in ever smokers.

Conclusion

Our results suggest that many miRNAs were significantly associated with BP in subgroups exposed to known hypertension risk factors. These findings shed light on the underlying molecular mechanisms of BP, and may assist with the development of a miRNA panel for early detection of hypertension.

Differential Effects of E2 on MAPK Activity in the Brain and Heart of Aged Female Rats

Aging and the coincident loss of circulating estrogens at menopause lead to increased risks for neurological and cardiovascular pathologies. Clinical studies show that estrogen therapy (ET) can be beneficial in mitigating these negative effects, in both the brain and heart, when it is initiated shortly after the perimenopausal transition. However, this same therapy is detrimental when initiated >10 years postmenopause. Importantly, the molecular mechanisms underlying this age-related switch in ET efficacy are unknown. Estrogen receptors (ERs) mediate the neuroprotective and cardioprotective functions of estrogens by modulating gene transcription or, non-genomically, by activating second messenger signaling pathways, such as mitogen activated protein kinases (MAPK). These kinases are critical regulators of cell signaling pathways and have widespread downstream effects. Our hypothesis is that age and estrogen deprivation following menopause alters the expression and activation of the MAPK family members p38 and ERK in the brain and heart. To test this hypothesis, we used a surgically induced model of menopause in 18 month old rats through bilateral ovariectomy (OVX) followed by an acute dose of 17β-estradiol (E2) administered at varying time points post-OVX (1 week, 4 weeks, 8 weeks, or 12 weeks). Age and E2 treatment differentially regulated kinase activity in both the brain and heart, and the effects were also brain region specific. MAPK signaling plays an integral role in aging, and the aberrant regulation of those signaling pathways might be involved in age-related disorders. Clinical studies show benefits of ET during early menopause but detrimental effects later, which might be reflective of changes in kinase expression and activation status.

Mitochondria-related miR-151a-5p reduces cellular ATP production by targeting CYTB in asthenozoospermia

Mitochondria, acting as the energy metabolism factory, participate in many key biological processes, including the maintenance of sperm viability. Mitochondria-related microRNA (miRNA), encoded by nuclear genome or mitochondrial genome, may play an important regulatory role in the control of mitochondrial function. To investigate the potential role of mitochondria-related miRNAs in asthenozoospermia, we adopted a strategy consisting of initial screening by TaqMan Low Density Array (TLDA) and further validation with quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Validation of the profiling results was conducted in two independent phases. Eventually, two seminal plasma miRNAs (sp-miRs) (miR-101-3p, let-7b-5p) were found to be significantly decreased, while sp-miR-151a-5p was significantly increased in severe asthenozoospermia cases compared with healthy controls. To further study their potential roles in asthenozoospermia, we then evaluated mitochondrial function of GC-2 cells transfected with these potentially functional miRNAs. Our results demonstrated that transfection with miR-151a-5p mimics decreased the mitochondrial respiratory activity. Besides, Adenosine Triphosphate (ATP) level was decreased when transfected with miR-151a-5p mimics. In addition, Cytochrome b (Cytb) mRNA and protein levels were also decreased when miR-151a-5p was overexpressed. These results indicate that miR-151a-5p may participate in the regulation of cellular respiration and ATP production through targeting Cytb.

Inflammasomes are neuroprotective targets for sex steroids

Neuroinflammation in the central nervous system is triggered by toxic stimuli or degenerative events, orchestrates the interplay of brain-intrinsic immune cells and neighboring neural cells, and sequentially allows leukocyte extravasation from the periphery into the brain parenchyma. During the inflammatory cascade, immune-competent cells become activated and secrete a plethora of cytokines and chemokines which form a local inflammatory signaling network important for warding off harmful stimuli to the host but are likewise necessary to preserve damaged brain tissue. Inflammatory responses are initiated by extra- and intra-cellular pathogen and danger-associated receptors. These signals are processed by multi-protein complexes termed inflammasomes which trigger the production of biologically active interleukins-1 and 18 after the cleavage of caspase-1. Estrogens and progesterone are neuroprotective and anti-inflammatory in diverse disease models of the brain in particular under acute inflammatory conditions such as stroke and traumatic brain injury. Both steroids are able to attenuate pro-inflammatory cytokine activity. Recent literature and our own studies provide convincing evidence that the anti-inflammatory potency of these steroids result from a complex interaction with the inflammasome activation and their up-stream regulatory network of miRNAs in brain-intrinsic innate immune cells. This article examines steroid-inflammasome interactions in the brain during brain injury and illuminates the importance of regulation initial upstream events during neuroinflammation. This article is part of a Special Issue entitled 'Steroid Perspectives'.

miR-23 regulate the pathogenesis of patients with coronary artery disease

To study whether miR-23 is regulated in coronary artery disease (CAD) patients and what is the possible mechanism of miR-23 in regulating CAD progression. Method Three different cohorts (including 13 AMI patients, 176 angina pectoris patients and 127 control subjects) were enrolled to investigate the expression levels of circulating miR-23 in patients with myocardial ischemia and also the relationship between plasma miR-23 and severity of coronary stenosis. Plasma miR-23 levels of participants were examined by real-time quantitative PCR. We further detected the correlation of miR-23 and VEGF by molecular and animal assays. Result miR-23 was enriched in not only diseased endothelial progenitor cells (EPCs) but also the plasma of CAD patients. Besides, we found out miR-23 was able to suppress VEGF expression and EPC activities. Reporter assays confirmed the direct binding and repression of miR-23 to the 3'-UTR of VEGF mRNA. Knock down of miR-23 not only restored VEGF levels and angiogenic activities of diseased EPCs in vitro, but further promoted blood flow recovery in ischemic limbs of mice. Conclusion Circulating miR-23 may be a new biomarker for CAD and as a potential diagnostic tool. And increased miR-23 level may be used to predict the presence and severity of coronary lesions in CAD patients.

Overexpression of NF90-NF45 Represses Myogenic MicroRNA Biogenesis, Resulting in Development of Skeletal Muscle Atrophy and Centronuclear Muscle Fibers

MicroRNAs (miRNAs) are involved in the progression and suppression of various diseases through translational inhibition of target mRNAs. Therefore, the alteration of miRNA biogenesis induces several diseases. The nuclear factor 90 (NF90)-NF45 complex is known as a negative regulator in miRNA biogenesis. Here, we showed that NF90-NF45 double-transgenic (dbTg) mice develop skeletal muscle atrophy and centronuclear muscle fibers in adulthood. Subsequently, we found that the levels of myogenic miRNAs, including miRNA 133a (miR-133a), which promote muscle maturation, were significantly decreased in the skeletal muscle of NF90-NF45 dbTg mice compared with those in wild-type mice. However, levels of primary transcripts of the miRNAs (pri-miRNAs) were clearly elevated in NF90-NF45 dbTg mice. This result indicated that the NF90-NF45 complex suppressed miRNA production through inhibition of pri-miRNA processing. This finding was supported by the fact that processing of pri-miRNA 133a-1 (pri-miR-133a-1) was inhibited via binding of NF90-NF45 to the pri-miRNA. Finally, the level of dynamin 2, a causative gene of centronuclear myopathy and concomitantly a target of miR-133a, was elevated in the skeletal muscle of NF90-NF45 dbTg mice. Taken together, we conclude that the NF90-NF45 complex induces centronuclear myopathy through increased dynamin 2 expression by an NF90-NF45-induced reduction of miR-133a expression in vivo.

Does sex influence the incidence or severity of reperfusion-induced cardiac arrhythmias?

Whether sex affects the acute phase of myocardial ischemia in experimental animal models is currently being debated. Our purpose was to determine if sex influences either the incidence or severity of reperfusion-induced arrhythmias resulting from a brief coronary occlusion. Male and female Sprague–Dawley rats were assigned to the study. Anesthetized animals were subjected to a 5-minute coronary artery occlusion followed by 5 minutes of reperfusion. Mortality differed by sex: 10/27 (37%) of males died due to VT/VF while only 1/16 females (6%) died due to VT/VF (p = 0.033). Quantitative analysis of the electrocardiogram was performed on data acquired from 17 male and 15 female survivors. Analysis showed no other significant differences in ventricular arrhythmias between the two groups. Conclusion: Lethal reperfusion-induced arrhythmias led to a higher mortality in male rats versus female rats. Among survivors there was no difference in any other arrhythmic parameters measured.

Arsenic responsive microRNAs in vivo and their potential involvement in arsenic-induced oxidative stress

Arsenic exposure is postulated to modify microRNA (miRNA) expression, leading to changes of gene expression and toxicities, but studies relating the responses of miRNAs to arsenic exposure are lacking, especially with respect to in vivo studies. We utilized high-throughput sequencing technology and generated miRNA expression profiles of liver tissues from Sprague Dawley (SD) rats exposed to various concentrations of sodium arsenite (0, 0.1, 1, 10 and 100mg/L) for 60days. Unsupervised hierarchical clustering analysis of the miRNA expression profiles clustered the SD rats into different groups based on the arsenic exposure status, indicating a highly significant association between arsenic exposure and cluster membership (p-value of 0.0012). Multiple miRNA expressions were altered by arsenic in an exposure concentration-dependent manner. Among the identified arsenic-responsive miRNAs, several are predicted to target Nfe2l2-regulated antioxidant genes, including glutamate-cysteine ligase (GCL) catalytic subunit (GCLC) and modifier subunit (GCLM) which are involved in glutathione (GSH) synthesis. Exposure to low concentrations of arsenic increased mRNA expression for Gclc and Gclm, while high concentrations significantly reduced their expression, which were correlated to changes in hepatic GCL activity and GSH level. Moreover, our data suggested that other mechanisms, e.g., miRNAs, rather than Nfe2l2-signaling pathway, could be involved in the regulation of mRNA expression of Gclc and Gclm post-arsenic exposure in vivo. Together, our findings show that arsenic exposure disrupts the genome-wide expression of miRNAs in vivo, which could lead to the biological consequence, such as an altered balance of antioxidant defense and oxidative stress.

Baculovirus-mediated miRNA regulation to suppress hepatocellular carcinoma tumorigenicity and metastasis

MicroRNA 122 (miR-122) is a tumor suppressor for hepatocellular carcinoma (HCC) but is lowly expressed in HCC cells. MiR-151 is aberrantly overexpressed in HCC cells and promotes HCC metastasis yet its roles on HCC tumorigenicity are unknown. To combat HCC tumorigenicity/metastasis, we developed Sleeping Beauty (SB)-based hybrid baculovirus (BV) vectors that expressed (i) miR-122 precursors (pre-miR-122), (ii) miR-151 sponges, or (iii) pre-miR-122 and miR-151 sponges. Transduction of aggressive HCC cells (Mahlavu) with the pre-miR-122-expressing BV tremendously enhanced miR-122 levels for >6 weeks, suppressed the levels of downstream effectors (e.g., ADAM10 and Bcl-w), proliferation, anchorage-independent growth, motility and migration/invasion in vitro. Intratumoral injection of the pre-miR-122-expressing BV attenuated the HCC growth/metastasis. The miR-151 sponges-expressing BV diminished the miR-151 levels for 6 weeks, enhanced RhoGDIA expression, suppressed RhoGTPases, as well as motility and migration/invasion of Mahlavu cells. Intratumoral injection of the miR-151 sponge-expressing BV impeded not only HCC metastasis but also cell proliferation, MMP expression and tumor growth in vivo. The BV co-expressing pre-miR-122 and miR-151 sponges also simultaneously enhanced miR-122 expression and inhibited miR-151, and conferred antitumor/anti-metastasis effects albeit lack of synergism. These data implicate the potentials of the SB-based hybrid BV for persistently modulating miRNA and suppressing HCC tumorigenicity/metastasis.

Estrogen regulation of protein expression and signaling pathways in the heart

Sex differences in cardiovascular disease and cardiac physiology have been reported in humans as well as in animal models. Premenopausal women have reduced cardiovascular disease compared to men, but the incidence of cardiovascular disease in women increases following menopause. Sex differences in cardiomyocytes likely contribute to the differences in male-female physiology and response to disease. Sex differences in the heart have been noted in electrophysiology, contractility, signaling, metabolism, and cardioprotection. These differences appear to be due, at least in part, to differences in gene and protein expression as well as in posttranslational protein modifications. This review will focus primarily on estrogen-mediated male-female differences in protein expression and signaling pathways in the heart and cardiac cells. It should be emphasized that these basic differences are not intrinsically beneficial or detrimental per se; the difference can be good or bad depending on the context and circumstances.