BET bromodomain inhibitors PFI-1 and JQ1 are identified in an epigenetic compound screen to enhance C9ORF72 gene expression and shown to ameliorate C9ORF72-associated pathological and behavioral abnormalities in a C9ALS/FTD model

BACKGROUND: An intronic GGGGCC (G4C2) hexanucleotide repeat expansion (HRE) in the C9ORF72 gene is the most common cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), referred to as C9ALS/FTD. No cure or effective treatment exist for C9ALS/FTD. Three major molecular mechanisms have emerged to explain C9ALS/FTD disease mechanisms: (1) C9ORF72 loss-of-function through haploinsufficiency, (2) dipeptide repeat (DPR) proteins mediated toxicity by the translation of the repeat RNAs, and more controversial, (3) RNA-mediated toxicity by bidirectional transcription of the repeats that form intranuclear RNA foci. Recent studies indicate a double-hit pathogenic mechanism in C9ALS/FTD, where reduced C9ORF72 protein levels lead to impaired clearance of toxic DPRs. Here we explored whether pharmacological compounds can revert these pathological hallmarks in vitro and cognitive impairment in a C9ALS/FTD mouse model (C9BAC). We specifically focused our study on small molecule inhibitors targeting chromatin-regulating proteins (epidrugs) with the goal of increasing C9ORF72 gene expression and reduce toxic DPRs. RESULTS: We generated luciferase reporter cell lines containing 10 (control) or \u3e /= 90 (mutant) G4C2 HRE located between exon 1a and 1b of the human C9ORF72 gene. In a screen of 14 different epidrugs targeting bromodomains, chromodomains and histone-modifying enzymes, we found that several bromodomain and extra-terminal domain (BET) inhibitors (BETi), including PFI-1 and JQ1, increased luciferase reporter activity. Using primary cortical cultures from C9BAC mice, we further found that PFI-1 treatment increased the expression of V1-V3 transcripts of the human mutant C9ORF72 gene, reduced poly(GP)-DPR inclusions but enhanced intranuclear RNA foci. We also tested whether JQ1, an BETi previously shown to reach the mouse brain by intraperitoneal (i.p.) injection, can revert behavioral abnormalities in C9BAC mice. Interestingly, it was found that JQ1 administration (daily i.p. administration for 7 days) rescued hippocampal-dependent cognitive deficits in C9BAC mice. CONCLUSIONS: Our findings place BET bromodomain inhibitors as a potential therapy for C9ALS/FTD by ameliorating C9ORF72-associated pathological and behavioral abnormalities. Our finding that PFI-1 increases accumulation of intranuclear RNA foci is in agreement with recent data in flies suggesting that nuclear RNA foci can be neuroprotective by sequestering repeat transcripts that result in toxic DPRs

Widespread loss of the silencing epigenetic mark H3K9me3 in astrocytes and neurons along with hippocampal-dependent cognitive impairment in C9orf72 BAC transgenic mice

Background: Hexanucleotide repeat expansions of the G4C2 motif in a non-coding region of the C9ORF72 gene are the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Tissues from C9ALS/FTD patients and from mouse models of ALS show RNA foci, dipeptide-repeat proteins, and notably, widespread alterations in the transcriptome. Epigenetic processes regulate gene expression without changing DNA sequences and therefore could account for the altered transcriptome profiles in C9ALS/FTD; here, we explore whether the critical repressive marks H3K9me2 and H3K9me3 are altered in a recently developed C9ALS/FTD BAC mouse model (C9BAC). Results: Chromocenters that constitute pericentric constitutive heterochromatin were visualized as DAPI- or Nucblue-dense foci in nuclei. Cultured C9BAC astrocytes exhibited a reduced staining signal for H3K9me3 (but not for H3K9me2) at chromocenters that was accompanied by a marked decline in the global nuclear level of this mark. Similar depletion of H3K9me3 at chromocenters was detected in astrocytes and neurons of the spinal cord, motor cortex, and hippocampus of C9BAC mice. The alterations of H3K9me3 in the hippocampus of C9BAC mice led us to identify previously undetected neuronal loss in CA1, CA3, and dentate gyrus, as well as hippocampal-dependent cognitive deficits. Conclusions: Our data indicate that a loss of the repressive mark H3K9me3 in astrocytes and neurons in the central nervous system of C9BAC mice represents a signature during neurodegeneration and memory deficit of C9ALS/FTD. © 2020 The Author(s).Indexación: Scopu

Assessment of Heavy Metal Concentration in Lokan from Sg. Geting, Tumpat, Kelantan and Associated Health Risk

This study is conducted for the health risk assessment of Lokan consumption from Sungai Geting in Tumpat, Kelantan. The objective of this study is to determine the concentration of lead, zinc, cadmium, copper, and arsenic in lokan. Furthermore, this study also aims to analyse the possible health risk associated with heavy metal accumulation via consumption of lokan by using Target Hazard Quotient (THQ). Lokan samples were collected from the fisherman and prepared according to wet digestion method. Heavy metal concentration was determined by ICP-MS. Target Hazard Quotients was used to calculated risk assessment to determine the total exposure of heavy metals to the consumer. The result shows that arsenic has the highest concentration in the sample compared to cadmium, lead, zinc and copper. Although the concentration of arsenic is high, the THQ value of arsenic was below than l which means that the consumer would not experience significant health risk from the consumption of lokan. The concentration of all the elements were found to be below the Malaysian Food Regulation 1985 (MFR 1985). Based on this study, it can be concluded that the consumption of lokan from Sungai Geting is safe for the consumers

Interfering of the Reelin/ApoER2/PSD95 Signaling Axis Reactivates Dendritogenesis of Mature Hippocampal Neurons

© 2016 Wiley Periodicals, Inc. Reelin, an extracellular glycoprotein secreted in embryonic and adult brain, participates in neuronal migration and neuronal plasticity. Extensive evidence shows that reelin via activation of the ApoER2 and VLDLR receptors promotes dendrite and spine formation during early development. Further evidence suggests that reelin signaling is needed to maintain a stable architecture in mature neurons, but, direct evidence is lacking. During activity-dependent maturation of the neuronal circuitry, the synaptic protein PSD95 is inserted into the postsynaptic membrane to induce structural refinement and stability of spines and dendrites. Given that ApoER2 interacts with PSD95, we tested if reelin signaling interference in adult neurons reactivates the dendritic architecture. Unlike findings in developing cultures, the presently obtained in vitro and in vivo data show, for the first time, that reelin signaling interference robustly increase dendritogenesis and redu

TREM2-Deficient Microglia Attenuate Tau Spreading In Vivo

The role of TREM2 in Alzheimer’s disease (AD) is not fully understood. Previous studies investigating the effect of TREM2 deletion on tauopathy mouse models without the contribution of b-amyloid have focused only on tau overexpression models. Herein, we investigated the effects of TREM2 deficiency on tau spreading using a mouse model in which endogenous tau is seeded to produce AD-like tau features. We found that Trem2−/− mice exhibit attenuated tau pathology in multiple brain regions concomitant with a decreased microglial density. The neuroinflammatory profile in TREM2-deficient mice did not induce an activated inflammatory response to tau pathology. These findings suggest that reduced TREM2 signaling may alter the response of microglia to pathological tau aggregates, impairing their activation and decreasing their capacity to contribute to tau spreading. However, caution should be exercised when targeting TREM2 as a therapeutic entry point for AD until its involvement in tau aggregation and propagation is better understood

NMDA receptor subunit composition controls dendritogenesis of hippocampal neurons through CAMKII, CREB-P, and H3K27ac

Dendrite arbor growth, or dendritogenesis, is choreographed by a diverse set of cues, including the NMDA receptor (NMDAR) subunits NR2A and NR2B. While NR1NR2B receptors are predominantly expressed in immature neurons and promote plasticity, NR1NR2A receptors are mainly expressed in mature neurons and induce circuit stability. How the different subunits regulate these processes is unclear, but this is likely related to the presence of their distinct C-terminal sequences that couple different signaling proteins. Calcium-calmodulin-dependent protein kinase II (CaMKII) is an interesting candidate as this protein can be activated by calcium influx through NMDARs. CaMKII triggers a series of biochemical signaling cascades, involving the phosphorylation of diverse targets. Among them, the activation of cAMP response element-binding protein (CREB-P) pathway triggers a plasticity-specific transcriptional program through unknown epigenetic mechanisms. Here, we found that dendritogenesis in hippocampal neurons is impaired by several well-characterized constructs (i.e., NR2B-RS/QD) and peptides (i.e., tatCN21) that specifically interfere with the recruitment and interaction of CaMKII with the NR2B C-terminal domain. Interestingly, we found that transduction of NR2AIN, a mutant NR2A construct with increased interaction to CaMKII, reactivates dendritogenesis in mature hippocampal neurons in vitro and in vivo. To gain insights into the signaling and epigenetic mechanisms underlying NMDAR-mediated dendritogenesis, we used immunofluorescence staining to detect CREB-P and acetylated lysine 27 of histone H3 (H3K27ac), an activation-associated histone tail mark. In contrast to control mature neurons, our data shows that activation of the NMDAR/CaMKII/ERK-P/CREB-P signaling axis in neurons expressing NR2AIN is not correlated with increased nuclear H3K27ac levels.FONDECYT 1140301 1101012 3130582 11130203 1140700 1150933 1130706 UNAB Nucleus DI-603-14N DRI USA 2013-0030 FP7-PEOPLE-IRSES 295185 FONDEQUIP EQM 140166 CONICYT 24110099 201161486 21151563 21151265 FONDAP 1509000

Epigenetic editing of the Dlg4/PSD95 gene improves cognition in aged and Alzheimer's disease mice

The Dlg4 gene encodes for post-synaptic density protein 95 (PSD95), a major synaptic protein that clusters glutamate receptors and is critical for plasticity. PSD95 levels are diminished in ageing and neurodegenerative disorders, including Alzheimer’s disease and Huntington’s disease. The epigenetic mechanisms that (dys)regulate transcription of Dlg4/PSD95, or other plasticity genes, are largely unknown, limiting the development of targeted epigenome therapy. We analysed the Dlg4/PSD95 epigenetic landscape in hippocampal tissue and designed a Dlg4/PSD95 gene-targeting strategy: a Dlg4/PSD95 zinc finger DNA-binding domain was engineered and fused to effector domains to either repress (G9a, Suvdel76, SKD) or activate (VP64) transcription, generating artificial transcription factors or epigenetic editors (methylating H3K9). These epi-editors altered critical histone marks and subsequently Dlg4/PSD95 expression, which, importantly, impacted several hippocampal neuron plasticity processes. Intriguingly, transduction of the artificial transcription factor PSD95-VP64 rescued memory deficits in aged and Alzheimer’s disease mice. Conclusively, this work validates PSD95 as a key player in memory and establishes epigenetic editing as a potential therapy to treat human neurological disorders