A psychiatric disease-related circular RNA controls synaptic gene expression and cognition.

Although circular RNAs (circRNAs) are enriched in the mammalian brain, very little is known about their potential involvement in brain function and psychiatric disease. Here, we show that circHomer1a, a neuronal-enriched circRNA abundantly expressed in the frontal cortex, derived from Homer protein homolog 1 (HOMER1), is significantly reduced in both the prefrontal cortex (PFC) and induced pluripotent stem cell-derived neuronal cultures from patients with schizophrenia (SCZ) and bipolar disorder (BD). Moreover, alterations in circHomer1a were positively associated with the age of onset of SCZ in both the dorsolateral prefrontal cortex (DLPFC) and orbitofrontal cortex (OFC). No correlations between the age of onset of SCZ and linear HOMER1 mRNA were observed, whose expression was mostly unaltered in BD and SCZ postmortem brain. Using in vivo circRNA-specific knockdown of circHomer1a in mouse PFC, we show that it modulates the expression of numerous alternative mRNA transcripts from genes involved in synaptic plasticity and psychiatric disease. Intriguingly, in vivo circHomer1a knockdown in mouse OFC resulted in specific deficits in OFC-mediated cognitive flexibility. Lastly, we demonstrate that the neuronal RNA-binding protein HuD binds to circHomer1a and can influence its synaptic expression in the frontal cortex. Collectively, our data uncover a novel psychiatric disease-associated circRNA that regulates synaptic gene expression and cognitive flexibility.

Developmental exposure to 50 parts-per-billion arsenic influences histone modifications and associated epigenetic machinery in a region- and sex-specific manner in the adult mouse brain.

Epidemiological studies report that arsenic exposure via drinking water adversely impacts cognitive development in children and, in adults, can lead to greater psychiatric disease susceptibility, among other conditions. While it is known that arsenic toxicity has a profound effect on the epigenetic landscape, very few studies have investigated its effects on chromatin architecture in the brain. We have previously demonstrated that exposure to a low level of arsenic (50ppb) during all three trimesters of fetal/neonatal development induces deficits in adult hippocampal neurogenesis in the dentate gyrus (DG), depressive-like symptoms, and alterations in gene expression in the adult mouse brain. As epigenetic processes control these outcomes, here we assess the impact of our developmental arsenic exposure (DAE) paradigm on global histone posttranslational modifications and associated chromatin-modifying proteins in the dentate gyrus and frontal cortex (FC) of adult male and female mice. DAE influenced histone 3K4 trimethylation with increased levels in the male DG and FC and decreased levels in the female DG (no change in female FC). The histone methyltransferase MLL exhibited a similar sex- and region-specific expression profile as H3K4me3 levels, while histone demethylase KDM5B expression trended in the opposite direction. DAE increased histone 3K9 acetylation levels in the male DG along with histone acetyltransferase (HAT) expression of GCN5 and decreased H3K9ac levels in the male FC along with decreased HAT expression of GCN5 and PCAF. DAE decreased expression of histone deacetylase enzymes HDAC1 and HDAC2, which were concurrent with increased H3K9ac levels but only in the female DG. Levels of H3 and H3K9me3 were not influenced by DAE in either brain region of either sex. These findings suggest that exposure to a low, environmentally relevant level of arsenic during development leads to long-lasting changes in histone methylation and acetylation in the adult brain due to aberrant expression of epigenetic machinery based on region and sex.

A bidirectional competitive interaction between circHomer1 and Homer1b within the orbitofrontal cortex regulates reversal learning.

Although circular RNAs (circRNAs) are enriched in the brain, their relevance for brain function and psychiatric disorders is poorly understood. Here, we show that circHomer1 is inversely associated with relative HOMER1B mRNA isoform levels in both the orbitofrontal cortex (OFC) and stem-cell-derived neuronal cultures of subjects with psychiatric disorders. We further demonstrate that in vivo circHomer1 knockdown (KD) within the OFC can inhibit the synaptic expression of Homer1b mRNA. Furthermore, we show that circHomer1 directly binds to Homer1b mRNA and that Homer1b-specific KD increases synaptic circHomer1 levels and improves OFC-mediated behavioral flexibility. Importantly, double circHomer1 and Homer1b in vivo co-KD results in a complete rescue in circHomer1-associated alterations in both chance reversal learning and synaptic gene expression. Lastly, we uncover an RNA-binding protein that can directly bind to circHomer1 and promote its biogenesis. Taken together, our data provide mechanistic insights into the importance of circRNAs in brain function and disease.

Arsenic exposure during embryonic development alters the expression of the long noncoding RNA growth arrest specific-5 (Gas5) in a sex-dependent manner.

Our previous studies suggest that prenatal arsenic exposure (50ppb) modifies epigenetic control of the programming of the glucocorticoid receptor (GR) signaling system in the developing mouse brain. These deficits may lead to long-lasting consequences, including deficits in learning and memory, increased depressive-like behaviors, and an altered set-point of GR feedback throughout life. To understand the arsenic-induced changes within the GR system, we assessed the impact of in utero arsenic exposure on the levels of the GR and growth arrest-specific-5 (Gas5), a noncoding RNA, across a key gestational period for GR programming (gestational days, GD 14-18) in mice. Gas5 contains a glucocorticoid response element (GRE)-like sequence that binds the GR, thereby decreasing GR-GRE-dependent gene transcription and potentially altering GR programming. Prenatal arsenic exposure resulted in sex-dependent and age-dependent shifts in the levels of GR and Gas5 expression in fetal telencephalon. Nuclear GR levels were reduced in males, but unchanged in females, at all gestational time points tested. Total cellular Gas5 levels were lower in arsenic-exposed males with no changes seen in arsenic-exposed females at GD16 and 18. An increase in total cellular Gas-5 along with increased nuclear levels in GD14 arsenic-exposed females, suggests a differential regulation of cellular compartmentalization of Gas5. RIP assays revealed reduced Gas5 associated with the GR on GD14 in the nuclear fraction prepared from arsenic-exposed males and females. This decrease in levels of GR-Gas5 binding continued only in the females at GD18. Thus, nuclear GR signaling potential is decreased in prenatal arsenic-exposed males, while it is increased or maintained at levels approaching normal in prenatal arsenic-exposed females. These findings suggest that females, but not males, exposed to arsenic are able to regulate the levels of nuclear free GR by altering Gas5 levels, thereby keeping GR nuclear signaling closer to control (unexposed) levels.

Sex-Dependent effects of developmental arsenic exposure on methylation capacity and methylation regulation of the glucocorticoid receptor system in the embryonic mouse brain.

Previously we have shown that prenatal moderate arsenic exposure (50 ppb) disrupts glucocorticoid receptor (GR) programming and that these changes continue into adolescence in males. However, it was not clear what the molecular mechanisms were promoting these GR programming changes or if these changes occurred in arsenic-exposed females. In the present studies, we assessed the effects of arsenic on protein and mRNA of the glucocorticoid receptor (GR) and 11ß-hydroxysteroid dehydrogenase (Hsd) isozymes and compared the levels of methylation within the promoters of the Nr3c1 and Hsd11b1 genes in female fetal brain at embryonic days (E) 14 and 18. Prenatal arsenate exposure produced sex specific effects on the glucocorticoid system. Compared to males, females were resistant to arsenic induced changes in GR, 11ß-Hsd-1 and 11ß-Hsd-2 protein levels despite observed elevations in Nr3c1 and Hsd11b2 mRNA. This sex-specific effect was not due to differences in the methylation of the GR promoter as methylation of the Nr3c1 gene was either unchanged (region containing the egr-1 binding site) or similarly reduced (region containing the SP-1 transcription factor binding site) in both males and females exposed to arsenic. Arsenic did produce sex and age-specific changes in the methylation of Hsd11b1 gene, producing increased methylation in females at E14 and decreased methylation at E18. These changes were not attributed to changes in DNMT levels. Since arsenate metabolism could interfere with the generation of methyl donor groups, we assessed glutathione (GSH), s-adenosylmethionine (SAM) and As 3 methyltransferase (As3MT). Exposed males and females had similar levels of As3MT and SAM; however, females had higher levels of GSH/GSSH. It is possible that this greater anti-oxidative capacity within the females provides protection against low to moderate arsenate. Our data suggest that the GR signaling system in female offspring was not as affected by prenatal arsenic and predicts that female arsenic-exposed mice should have normal GR feedback regulation.

Outcomes of Patients Treated with the Everolimus- versus the Paclitaxel-Eluting Stents in a Consecutive Cohort of Patients at a Tertiary Medical Center.

In this study, we compare the outcomes of the paclitaxel-eluting stent (PES) versus the everolimus-eluting stent (EES) treated patients at a tertiary medical center and up to 2 years follow-up. Unselected consecutive patients were retrospectively recruited following stenting with PES (159 patients) or EES (189 patients). The primary endpoint of the study was target lesion failure (TLF), defined as the combined endpoint of cardiac death, nonfatal myocardial infarction (MI), or target lesion revascularization (TLR). Secondary endpoints included target vessel revascularization (TVR), TLR, target vessel failure (TVF), acute stent thrombosis (ST), total death, cardiac death, and nonfatal MI. Patients treated with the PES stent had less congestive heart failure and restenotic lesions, but a higher prevalence of longer lesions, nonleft main bifurcations, required more stents per patient (4.3 ± 2.8 vs. 2.9 ± 2.1). TLF occurred in 32.3% PES versus 21.5% EES (p = 0.027). The secondary unadjusted endpoints for PES versus EES, respectively, were TVF 38.6 versus 30.7% (p = 0.140), TVR 35.7 versus 26.5% (p = 0.079), definite and probable ST 1.2 versus 0.0%, nonfatal MI 4.5 versus 4.2%, and mortality 9.6 versus 4.0%. Logistic regression analysis showed that the numbers of stents per patient (p = 0.001), age (p = 0.01), and renal failure (p = 0.045) were independent predictors of TLF. Using univariate analysis, EES had lower TLF than PES in a cohort of unselected patients undergoing percutaneous coronary intervention at 2 years follow-up. Multivariate analysis showed that the numbers of stents per patient, age, and renal failure, but not stent type, were predictors of TLF.

Safety and One-Year revascularization outcome of excimer laser ablation therapy in treating in-stent restenosis of femoropopliteal arteries: A retrospective review from a single center.

BACKGROUND: Treatment of in-stent restenosis of the femoropopliteal (FP) arteries is challenging with a high rate of restenosis. Excimer laser atherectomy (ELA) has a theoretical advantage of ablating restenotic tissue and reducing or delaying the need for repeat revascularization. We present a retrospective analysis from our center on the outcomes of ELA in the treatment of in-stent restenosis of the FP arteries. METHODS: Demographic, clinical, angiographic and procedural data were collected on all patients that underwent ELA for in-stent restenosis from February 2005 to April 2010 at a single medical center. Major adverse events and one-year target lesion revascularization (TLR) and target vessel revascularization (TVR) were obtained by reviewing of medical records. Descriptive analysis was performed on all variables. Kaplan-Meier survival curves for TLR were plotted. RESULTS: 40 consecutive patients (mean age 67.7±9.0years, 57.5% males) were included and followed for 1year. Adjunctive balloon angioplasty was performed in 100% at a mean pressure of 12.4±2.9atm. Acute procedural success (<30% angiographic residual narrowing) occurred in 92.5% of patients. Embolic filter protection (EFP) was used in 57.5% of patients. Bailout stenting was 50.0%. Macrodebris was noted in 65.2% of filters. The following adverse events were reported: distal embolization (DE) requiring treatment 2.5% (1 patient with no EFP); planned minor amputation 2.6%, planned major amputation 2.6%, total death 7.7% (all cardiac related). One perforation occurred treated successfully with stenting and balloon inflation. At one year, TLR and TVR occurred in 48.7% and 48.7% respectively. CONCLUSION: ELA has an overall favorable acute result in treating in-stent restenosis of the FP arteries. At one year TLR and TVR remain clinically significant. DE also occurs significantly with ELA and is effectively prevented with EFP.