Epigenetic modulation of Homer1a transcription regulation in amygdala and hippocampus with pavlovian fear conditioning.

The consolidation of conditioned fear involves upregulation of genes necessary for long-term memory formation. An important question remains as to whether this results in part from epigenetic regulation and chromatin modulation. We examined whether Homer1a, which is required for memory formation, is necessary for Pavlovian cued fear conditioning, whether it is downstream of BDNF-TrkB activation, and whether this pathway utilizes histone modifications for activity-dependent transcriptional regulation. We initially found that Homer1a knock-out mice exhibited deficits in cued fear conditioning (5 tone-shock presentations with 70 dB, 6 kHz tones and 0.5 s, 0.6 mA footshocks). We then demonstrated that: (1) Homer1a mRNA increases after fear conditioning in vivo within both amygdala and hippocampus of wild-type mice; (2) it increases after BDNF application to primary hippocampal and amygdala cultures in vitro; and (3) these increases are dependent on transcription and MAPK signaling. Furthermore, using chromatin immunoprecipitation we found that both in vitro and in vivo manipulations result in decreases in Homer1 promoter H3K9 methylation in amygdala cells but increases in Homer1 promoter H3 acetylation in hippocampal cells. However, no changes were observed in H4 acetylation or H3K27 dimethylation. Inhibition of histone deacetylation by sodium butyrate enhanced contextual but not cued fear conditioning and enhanced Homer1 H3 acetylation in the hippocampus. These data provide evidence for dynamic epigenetic regulation of Homer1a following BDNF-induced plasticity and during a BDNF-dependent learning process. Furthermore, upregulation of this gene may be regulated through distinct epigenetic modifications in the hippocampus and amygdala.

Long Noncoding RNA LINC01410 Suppresses Tumorigenesis and Enhances Radiosensitivity in Neuroblastoma Cells Through Regulating miR-545-3p/HK2 Axis.

BACKGROUND: Abnormal expression of long noncoding RNAs (lncRNAs) was often involved in tumorigenesis and radiosensitivity of various cancers. The aim of this study was to explore the biological function and regulatory mechanism of lncRNA long intergenic non-protein coding RNA 1410 (LINC01410) in tumorigenesis and radiosensitivity of neuroblastoma (NB). METHODS: The expression of LINC01410, microRNA-329-3p (miR-545-3p) and hexokinase 2 (HK2) was detected by quantitative real-time polymerase chain reaction (qRT-PCR). Methylthiazolyldiphenyl tetrazolium bromide (MTT) assay, colony formation assay and transwell assay were utilized to detect cell viability, colony formation and cell invasion abilities. Glucose consumption or lactate production was measured by glucose assay kit or lactate assay kit, respectively. The interaction between miR-545-3p and LINC01410 or HK2 was predicted by starBase v2.0 and verified by dual-luciferase reporter, RNA Immunoprecipitation (RIP) and RNA pull-down assays. Western blot was used to measure the protein expression of HK2. The mice xenograft model was established to investigate the role of LINC01410 in vivo. RESULTS: LINC01410 and HK2 were highly expressed while miR-545-3p was lowly expressed in NB tissues and cells. LINC01410 knockdown inhibited tumorigenesis by repressing cell proliferation and invasion, and increased the radiosensitivity via inhibiting colony formation rates and glycolysis. LINC01410 knockdown also suppressed tumor growth in vivo. Moreover, miR-545-3p could bind to LINC01410 and its downregulation reversed the effects of LINC01410 knockdown on tumorigenesis and radiosensitivity. Additionally, HK2 was a direct target of miR-545-3p and its overexpression attenuated the effects of miR-545-3p restoration on suppression of tumorigenesis and promotion of radiosensitivity. Besides, LINC01410 functioned as a molecular sponge of miR-545-3p to regulate HK2 expression. CONCLUSION: LINC01410 interference inhibited tumorigenesis and increased radiosensitivity via regulating miR-545-3p/HK2 axis, providing a novel therapeutic strategy for NB.

Lifetime Risk of Atrial Fibrillation by Race and Socioeconomic Status: ARIC Study (Atherosclerosis Risk in Communities).

BACKGROUND: Limited information exists on the lifetime risk of atrial fibrillation (AF) in African Americans and by socioeconomic status. METHODS: We studied 15 343 participants without AF at baseline from the ARIC (Atherosclerosis Risk in Communities) cohort recruited in 1987 to 1989 from 4 communities in the United States when they were 45 to 64 years of age. Participants have been followed through 2014. Incidence rates of AF were calculated dividing the number of new cases by person-years of follow-up. Lifetime risk of AF was estimated by a modified Kaplan-Meier method considering death as a competing risk. Participants' family income and education were obtained at baseline. RESULTS: We identified 2760 AF cases during a mean follow-up of 21 years. Lifetime risk of AF was 36% (95% confidence interval, 32%-38%) in white men, 30% (95% confidence interval, 26%-32%) in white women, 21% (95% confidence interval, 13%-24%) in African American men, and 22% (95% confidence interval, 16%-25%) in African American women. Regardless of race and sex, incidence rates of AF decreased from the lowest to the highest categories of income and education. In contrast, lifetime risk of AF increased in individuals with higher income and education in most sex-race groups. Cumulative incidence of AF was lower in those with higher income and education compared with their low socioeconomic status counterparts through earlier life but was reversed after age 80. CONCLUSIONS: Lifetime risk of AF in the ARIC cohort was ≈1 in 3 among whites and 1 in 5 among African Americans. Socioeconomic status was inversely associated with cumulative incidence of AF before the last decades of life.

Flow cytometric data analysis of circulating progenitor cell stability.

A recent publication by Mekonnen et al. demonstrated that among women with non-obstructive coronary artery disease, higher levels of circulating progenitor cells in the blood (CPC), were associated with impaired coronary flow reserve [1]. We performed a quality control assessment of the stability of circulating blood progenitor cells in blood samples stored at 4 °C, to determine the time period during which blood samples can be analyzed and yield consistent data for progenitor cell content. Healthy volunteers (n=6) were recruited and underwent phlebotomy, and blood was stored in EDTA tubes at 4 °C. Flow cytometry was performed to quantitate progenitor cell subsets at 0-4 h, 24 h, and 48 h post phlebotomy. All processed samples were fixed with 1% Paraformaldehyde and 1,000,000 total data events were collected. We found no significant differences in PC data for both CD34+ (P=0.68 for one-way ANOVA) and CD34+/CD133+ (P=0.74 for one-way ANOVA).

Circulating progenitor cells and coronary microvascular dysfunction: Results from the NHLBI-sponsored Women's Ischemia Syndrome Evaluation - Coronary Vascular Dysfunction Study (WISE-CVD).

BACKGROUND AND AIMS: Ischemia stimulates a reparative response resulting in mobilization of circulating progenitor cells (CPCs). We hypothesized that women with chronic myocardial ischemia from coronary microvascular disease (CMD) will mobilize CPCs. METHODS: In 123 women with ischemic symptoms and signs but no obstructive coronary artery disease (CAD) enrolled in the Women's Ischemia Syndrome Evaluation - Coronary Vascular Dysfunction Study (WISE-CVD), we measured coronary flow reserve (CFR) in response to intracoronary adenosine. Peripheral blood CPCs were measured using flow cytometry for expression of CD34, CD133, CXCR4, and VEGFR2. RESULTS: Subjects were 53 ± 11 years, BMI 30 ± 8; 44% hypertensive, 11% diabetic, 23% hyperlipidemic and 7% smokers. Lower CFR correlated inversely with higher levels of hematopoietic-enriched CD34+ (r = -0.23, p = 0.011), CD34+/CD133+ (r = -0.24, p = 0.008), and CD34+/CXCR4+ (r = -0.19, p = 0.036) cells. In multivariable regression analyses, after adjusting for traditional cardiovascular risk factors, lower CFR remained significantly associated with elevated levels of CD34+ (ß -0.18, p = 0.042), CD34+/CD133+ (ß -0.24, p = 0.036), and CD34+/CXCR4+ (ß -0.22, p = 0.050) cells. We found no association between CFR and CD34+/VEGFR2+ cells. CONCLUSIONS: In women with non-obstructive CAD, impaired CFR is associated with higher levels of CPCs, suggesting that chronic myocardial ischemia from CMD stimulates CPC mobilization. The functional significance of elevated CPCs in these subjects requires further investigation as a potential biomarker and treatment target.

PTEN recruitment controls synaptic and cognitive function in Alzheimer's models.

Dyshomeostasis of amyloid-ß peptide (Aß) is responsible for synaptic malfunctions leading to cognitive deficits ranging from mild impairment to full-blown dementia in Alzheimer's disease. Aß appears to skew synaptic plasticity events toward depression. We found that inhibition of PTEN, a lipid phosphatase that is essential to long-term depression, rescued normal synaptic function and cognition in cellular and animal models of Alzheimer's disease. Conversely, transgenic mice that overexpressed PTEN displayed synaptic depression that mimicked and occluded Aß-induced depression. Mechanistically, Aß triggers a PDZ-dependent recruitment of PTEN into the postsynaptic compartment. Using a PTEN knock-in mouse lacking the PDZ motif, and a cell-permeable interfering peptide, we found that this mechanism is crucial for Aß-induced synaptic toxicity and cognitive dysfunction. Our results provide fundamental information on the molecular mechanisms of Aß-induced synaptic malfunction and may offer new mechanism-based therapeutic targets to counteract downstream Aß signaling.

RXR-induced TNF-alpha suppression is reversed by morphine in activated U937 cells.

Deficiency in vitamin A has been associated with adverse clinical outcomes in drug users with HIV-1 infection. Retinoids have been demonstrated to suppress proinflammatory cytokine production by immune cells in vitro. These effects are induced by ligand-mediated activation of the retinoid receptors--retinoic acid receptor (RAR) and retinoid X receptor (RXR). In these studies, the effects of all-trans-retinoid acid (ATRA, a RAR agonist), 9-cis-retinoic acid (9cis RA; RAR and RXR agonist), LG101305 (RXR agonist), LG100815 (RAR antagonist) and LG101208 (RXR antagonist) on TNF-alpha production by phytohemagglutanin-activated U937 cells and the modulation of these effects by morphine were examined. TNF-alpha production was suppressed in all cultures exposed to retinoid agonist and antagonist agents. For cells exposed to RXR agonists or RAR antagonist, incubation with morphine resulted in the reversal of TNF-alpha suppression and this effect was inhibited by naloxone. These data suggest that interactions between RXR and morphine are involved in the immune effects of retinoids on TNF-alpha production by activated U937 cells. Such information may be important for understanding interactions between drugs of abuse and immune function in individuals with chronic proinflammatory states such as HIV-1 infection.

Transient hypoxia induces sequestration of M1 and M2 muscarinic acetylcholine receptors.

Oxidative stress has been implicated in impairing muscarinic acetylcholine receptor (mAChR) signaling activity. It remains unclear, however, whether alterations in the cell surface distribution of mAChRs following oxidative stress contribute to the diminished mAChR signaling activity. We report here that M1 and M2 mAChRs, stably expressed in Chinese hamster ovary cells, undergo sequestration following transient hypoxic-induced oxidative stress (2% O2). Sequestration of M1 and M2 mAChRs following transient hypoxia was associated with an increase in phosphorylation of these receptors. Over-expression of a catalytically inactive G protein-coupled receptor kinase 2 (GRK2 K220R) blocked the increased phosphorylation and sequestration of the M2, but not M1, mAChRs following transient hypoxia. Hypoxia induced phosphorylation and sequestration of the M1 mAChR was, however, blocked by over-expression of a catalytically inactive casein kinase 1 alpha (CK1alpha K46R). These results are the first demonstration that M1 and M2 mAChRs undergo sequestration following transient hypoxia. The data suggest that increased phosphorylation of M1 and M2 mAChRs underlies the mechanism responsible for sequestration of these receptors following transient hypoxia. We report here that distinct pathways involving CK1alpha and GRK2 mediated sequestration of M1 and M2 mAChRs following transient hypoxic-induced oxidative stress.