Impaired striatal dopamine release in homozygous Vps35 D620N knock-in mice.

Point mutations in the vacuolar protein sorting 35 gene (VPS35) have been associated with an autosomal dominant form of late-onset Parkinson disease (PARK17), but there has been considerable debate over whether it is caused by a loss- or gain-of-function mechanism and over the intracellular target site of neurotoxicity. To investigate the pathogenesis of PARK17 in vivo, we generated Vps35 D620N knock-in (KI) mice, expressing the homologous mutant protein with endogenous patterns of expression, simultaneously with Vps35 deletion 1 (Del1) mice, which carry 1bp deletion in the exon15 of Vps35, by CRISPR/Cas9-mediated genome engineering. Neither homozygous nor heterozygous Vps35 D620N KI mice suffered from premature death or developed clear neurodegeneration up to 70 weeks of age. Vps35 Del1 allele appeared to be a null or at least severely hypomorphic allele and homozygous Vps35 Del1 showed early embryonic lethality. Heterozygous crossings between Del1 and D620N knock-in mice revealed that the D620N/Del1 compound heterozygous mice, but not heterozygous Del1 mice, suffered from survival disadvantage. In vivo microdialysis showed that DA release evoked by 120 mM potassium chloride was significantly reduced in the caudate putamen of adult homozygous Vps35 D620N KI mice. Taken together, these results suggest that Vps35 D620N allele is a partial-loss-of-function allele and that such a genetic predisposition and age-related alterations in the nigrostriatal dopamine system cooperatively influence the pathogenesis of PARK17.

Conditional ablation of brain-derived neurotrophic factor-TrkB signaling impairs striatal neuron development.

Neurotrophic factors, such as brain-derived neurotrophic factor (BDNF), are associated with the physiology of the striatum and the loss of its normal functioning under pathological conditions. The role of BDNF and its downstream signaling in regulating the development of the striatum has not been fully investigated, however. Here we report that ablation of Bdnf in both the cortex and substantia nigra depletes BDNF in the striatum, and leads to impaired striatal development, severe motor deficits, and postnatal lethality. Furthermore, striatal-specific ablation of TrkB, the gene encoding the high-affinity receptor for BDNF, is sufficient to elicit an array of striatal developmental abnormalities, including decreased anatomical volume, smaller neuronal nucleus size, loss of dendritic spines, reduced enkephalin expression, diminished nigral dopaminergic projections, and severe deficits in striatal dopamine signaling through DARPP32. In addition, TrkB ablation in striatal neurons elicits a non-cell-autonomous reduction of tyrosine hydroxylase protein level in the axonal projections of substantia nigral dopaminergic neurons. Thus, our results establish an essential function for TrkB in regulating the development of striatal neurons.

TrkA gene ablation in basal forebrain results in dysfunction of the cholinergic circuitry.

Dysfunction of basal forebrain cholinergic neurons (BFCNs) is an early pathological hallmark of Alzheimer's disease (AD). Numerous studies have indicated that nerve growth factor (NGF) supports survival and phenotypic differentiation of BFCNs. Consistent with a potential link to AD pathogenesis, TrkA, a NGF receptor, is expressed in cholinergic forebrain neuronal populations including those in BF and striatum, and is markedly reduced in individuals with mild cognitive impairment (MCI) without dementia and early-stage AD. To investigate the role of TrkA in the development, connectivity, and function of the BF cholinergic system and its contribution to AD pathology, we have generated a forebrain-specific conditional TrkA knock-out mouse line. Our findings show a key role for TrkA signaling in establishing the BF cholinergic circuitry through the ERK pathway, and demonstrate that the normal developmental increase of choline acetyltransferase expression becomes critically dependent on TrkA signaling before neuronal connections are established. Moreover, the anatomical and physiological deficits caused by lack of TrkA signaling in BFCNs have selective impact on cognitive activity. These data demonstrate that TrkA loss results in cholinergic BF dysfunction and cognitive decline that is reminiscent of MCI and early AD.

Long-term efficacy and safety of erenumab in Japanese patients with episodic and chronic migraine: results from a 28-week open-label treatment period of a randomised trial.

OBJECTIVES: To evaluate the 1-year efficacy and safety of once-monthly erenumab 70 mg following a 24-week double-blind treatment period (DBTP) of a phase III randomised study of Japanese patients with episodic migraine (EM) or chronic migraine (CM). DESIGN: Multicentre open-label study. SETTING: A total of 41 centres in Japan. PARTICIPANTS: Patients completing the DBTP continued into the 28-week open-label treatment period (OLTP). 254 of 261 (97.3%) randomised patients continued into the OLTP; 244 (93.5%) completed treatment. INTERVENTIONS: Once-monthly subcutaneous erenumab 70 mg. MAIN OUTCOME MEASURES: Changes from baseline in monthly migraine days (MMD) and monthly acute migraine-specific medication treatment days (MSMD) reported via patient eDiary; proportion of ≥50% and ≥75% responders in MMD reduction from baseline; incidence and exposure-adjusted incidence of treatment-emergent adverse events (TEAEs). RESULTS: At week 24 of the DBTP, the mean (SE) change from baseline in MMD for the erenumab group was -3.8 (0.4) days (EM, -3.0 (0.4); CM, -5.2 (0.8)); in MSMD, -2.6 (0.4) days (EM, -2.1 (0.4); CM, -3.4 (0.7)). At the end of the OLTP (52 weeks postbaseline), the mean (SE) change from baseline in MMD was -4.7 (0.3) days (EM, -3.4 (0.3); CM, -6.9 (0.6)); in MSMD, -3.3 (0.3) days (EM, -2.4 (0.3); CM, -4.6 (0.5)). The proportion of ≥50% responders for MMD reduction in the erenumab group was 34.1% at week 24; 44.4% at week 52. The exposure-adjusted incidence of TEAEs was 219.7 per 100 patient-years during the OLTP (DBTP, 251.0 for the erenumab group). The most common TEAEs during the OLTP were nasopharyngitis, constipation and influenza. No new safety concerns were identified. CONCLUSIONS: Erenumab treatment was associated with reduced migraine frequency in Japanese patients with EM or CM for up to 1 year. Overall safety results from the OLTP were consistent with DBTP results. TRIAL REGISTRATION NUMBER: NCT03812224.

Efficacy of Erenumab for Migraine Prevention in Japanese Patients with Episodic and Chronic Migraine: Results of a Post-Hoc Pooled Analysis.

INTRODUCTION: Erenumab, a fully human monoclonal antibody against the calcitonin gene-related peptide receptor, is approved in Japan for the prevention of adult migraine. This post-hoc analysis evaluated the efficacy of erenumab in Japanese patients with low-frequency episodic migraine (LFEM) versus those with high-frequency episodic migraine (HFEM) and chronic migraine (CM). METHODS: A pooled analysis of data from the 24-week double-blind treatment phases (DBTPs) of phase 2 and 3 studies evaluated the efficacy of once-monthly erenumab 70 mg in Japanese patients. Patients were categorized into subgroups by monthly migraine days (MMD): LFEM and HFEM/CM. The main efficacy outcomes were change from baseline in MMD, acute migraine-specific medication treatment days (MSMD), and six-item Headache Impact Test (HIT-6™) scores. RESULTS: Patients with migraine (n = 532) were included in the analysis (LFEM, n = 215; HFEM, n = 215; CM, n = 102). Overall, mean age was 44 years, 86.5% were female, and 63.3-88.2% had used or were taking migraine preventive treatment at baseline. Throughout the DBTP, the placebo-adjusted mean change from baseline in MMD, MSMD, and HIT-6 scores with erenumab was similar across LFEM and HFEM/CM subgroups. The proportion of patients achieving at least 50% or 75% reduction from baseline in MMD and MSMD was similar across migraine frequency groups. Reduction in MMD moderately correlated with improvement in HIT-6 scores in the LFEM and HFEM/CM groups. Furthermore, the proportion of patients converting from HFEM/CM to LFEM during the DBTP was higher in the erenumab group than in the placebo. CONCLUSION: In Japanese patients with different migraine frequencies, erenumab treatment resulted in significant improvements in MMD, MSMD, and headache impact. This pooled analysis of data from phase 2 and 3 studies increases confidence that erenumab is efficacious in patients with high MMD, which is associated with increased disability.

Separation-related rapid nuclear transport of DNA/RNA heteroduplex oligonucleotide: unveiling distinctive intracellular trafficking.

DNA/RNA heteroduplex oligonucleotide (HDO), composed of DNA/locked nucleic acid (LNA) antisense oligonucleotide (ASO) and complementary RNA, is a next-generation antisense therapeutic agent. HDO is superior to the parental ASO in delivering to target tissues, and it exerts a more potent gene-silencing effect. In this study, we aimed to elucidate the intracellular trafficking mechanism of HDO-dependent gene silencing. HDO was more preferably transferred to the nucleus after transfection compared to the parental ASO. To determine when and where HDO is separated into the antisense strand (AS) and complementary strand (CS), we performed live-cell time-lapse imaging and fluorescence resonance energy transfer (FRET) assays. These assays demonstrated that HDO had a different intracellular trafficking mechanism than ASO. After endocytosis, HDO was separated in the early endosomes, and both AS and CS were released into the cytosol. AS was more efficiently transported to the nucleus than CS. Separation, endosomal release, and initiation of nuclear transport were a series of time-locked events occurring at a median of 30 s. CS cleavage was associated with efficient nuclear distribution and gene silencing in the nucleus. Understanding the unique intracellular silencing mechanisms of HDO will help us design more efficient drugs and might also provide insight into innate DNA/RNA cellular biology.

Cytosolic Genomic DNA functions as a Natural Antisense.

Stress conditions such as UV irradiation, exposure to genotoxic agents, stalled DNA replication, and even tumors trigger the release of cytosolic genomic DNA (cgDNA). Classically, cgDNA induces interferon response via its binding to proteins such as STING. In this study, we found previously reported cgDNA (cg721) exists in the cytosol of the mouse cell lines, cultured under no stress conditions. The overexpression of cg721 suppressed the complementary RNA expression using strand selection and knockdown of DNA/RNA hybrid R-loop removing enzyme RNase H and three prime repair exonuclease 1 TREX1 increased the expression levels of cg721 and thus, inhibited the target Naa40 transcript, as well as protein expression, with a phenotypic effect. In addition, cgDNA was incorporated into extracellular vesicles (EVs), and the EV-derived cg721 inhibited gene expression of the acceptor cells. Thus, our findings suggest that cg721 functions as a natural antisense DNA and play a role in cell-to-cell gene regulation once it secreted outside the cell as EVs.

Sphingosine-1-Phosphate Receptor-1 Selective Agonist Enhances Collateral Growth and Protects against Subsequent Stroke.

BACKGROUND AND PURPOSE: Collateral growth after acute occlusion of an intracranial artery is triggered by increasing shear stress in preexisting collateral pathways. Recently, sphingosine-1-phosphate receptor-1 (S1PR1) on endothelial cells was reported to be essential in sensing fluid shear stress. Here, we evaluated the expression of S1PR1 in the hypoperfused mouse brain and investigated the effect of a selective S1PR1 agonist on leptomeningeal collateral growth and subsequent ischemic damage after focal ischemia. METHODS: In C57Bl/6 mice (n = 133) subjected to unilateral common carotid occlusion (CCAO) and sham surgery. The first series examined the time course of collateral growth, cell proliferation, and S1PR1 expression in the leptomeningeal arteries after CCAO. The second series examined the relationship between pharmacological regulation of S1PR1 and collateral growth of leptomeningeal anastomoses. Animals were randomly assigned to one of the following groups: LtCCAO and daily intraperitoneal (i.p.) injection for 7 days of an S1PR1 selective agonist (SEW2871, 5 mg/kg/day); sham surgery and daily i.p. injection for 7 days of SEW2871 after surgery; LtCCAO and daily i.p. injection for 7 days of SEW2871 and an S1PR1 inverse agonist (VPC23019, 0.5 mg/kg); LtCCAO and daily i.p. injection of DMSO for 7 days after surgery; and sham surgery and daily i.p. injection of DMSO for 7 days. Leptomeningeal anastomoses were visualized 14 days after LtCCAO by latex perfusion method, and a set of animals underwent subsequent permanent middle cerebral artery occlusion (pMCAO) 7 days after the treatment termination. Neurological functions 1 hour, 1, 4, and 7 days and infarction volume 7 days after pMCAO were evaluated. RESULTS: In parallel with the increase in S1PR1 mRNA levels, S1PR1 expression colocalized with endothelial cell markers in the leptomeningeal arteries, increased markedly on the side of the CCAO, and peaked 7 days after CCAO. Mitotic cell numbers in the leptomeningeal arteries increased after CCAO. Administration of the S1PR1 selective agonist significantly increased cerebral blood flow (CBF) and the diameter of leptomeningeal collateral vessels (42.9 ± 2.6 µm) compared with the controls (27.6 ± 5.7 µm; P < 0.01). S1PR1 inverse agonist administration diminished the effect of the S1PR1 agonist (P < 0.001). After pMCAO, S1PR1 agonist pretreated animals showed significantly smaller infarct volume (17.5% ± 4.0% vs. 7.7% ± 4.0%, P < 0.01) and better functional recovery than vehicle-treated controls. CONCLUSIONS: These results suggest that S1PR1 is one of the principal regulators of leptomeningeal collateral recruitment at the site of increased shear stress and provide evidence that an S1PR1 selective agonist has a role in promoting collateral growth and preventing of ischemic damage and neurological dysfunction after subsequent stroke in patients with intracranial major artery stenosis or occlusion.

Enhanced Phospholipase A2 Group 3 Expression by Oxidative Stress Decreases the Insulin-Degrading Enzyme.

Oxidative stress has a ubiquitous role in neurodegenerative diseases and oxidative damage in specific regions of the brain is associated with selective neurodegeneration. We previously reported that Alzheimer disease (AD) model mice showed decreased insulin-degrading enzyme (IDE) levels in the cerebrum and accelerated phenotypic features of AD when crossbred with alpha-tocopherol transfer protein knockout (Ttpa-/-) mice. To further investigate the role of chronic oxidative stress in AD pathophysiology, we performed DNA microarray analysis using young and aged wild-type mice and aged Ttpa-/- mice. Among the genes whose expression changed dramatically was Phospholipase A2 group 3 (Pla2g3); Pla2g3 was identified because of its expression profile of cerebral specific up-regulation by chronic oxidative stress in silico and in aged Ttpa-/- mice. Immunohistochemical studies also demonstrated that human astrocytic Pla2g3 expression was significantly increased in human AD brains compared with control brains. Moreover, transfection of HEK293 cells with human Pla2g3 decreased endogenous IDE expression in a dose-dependent manner. Our findings show a key role of Pla2g3 on the reduction of IDE, and suggest that cerebrum specific increase of Pla2g3 is involved in the initiation and/or progression of AD.