scholarly journals Involvement of Epigenetic Promoter DNA Methylation of miR-124 in the Pathogenesis of HIV-1-Associated Neurocognitive Disorders

2018 ◽  
Vol 11 ◽  
pp. 251686571880690 ◽  
Author(s):  
Shilpa Buch ◽  
Palsamy Periyasamy ◽  
Minglei Guo
Keyword(s):  
Dna Methylation ◽  
Microglial Activation ◽  
Viral Proteins ◽  
Neurocognitive Disorders ◽  
Microglial Cells ◽  
Adjunctive Treatment ◽  
Viral Reservoirs ◽  
Stat3 Signaling ◽  
Promoter Dna ◽  
Hiv 1

Despite the efficacy of combination antiretroviral therapy (cART) in controlling viremia, the central nervous system (CNS) continues to harbor viral reservoirs. The persistence of low-level virus replication leads to the accumulation of early viral proteins, including HIV-1 Transactivator of transcription (HIV-1 Tat) protein. Based on the premise that cART does not impact levels of HIV-1 Tat, and since the CNS is inaccessible to the cART regimens, HIV-1-Tat-mediated neuroinflammation has been implicated as an underlying mediator of HIV-1-associated neurocognitive disorders (HAND). The mechanism(s) underlying the pathogenesis of HAND, however, remain less understood. Understanding the epigenetic/molecular mechanism(s) by which viral proteins such as HIV-1 Tat activate microglia is thus of paramount importance. The study published by Periyasamy et al provides new mechanistic insights into the role of HIV-1-Tat-mediated DNA methylation of miR-124 promoter in regulating microglial activation via the MECP2-STAT3 signaling axis. Furthermore, the authors have also reported that exposure of mouse primary microglial cells to HIV-1 Tat notably increased DNA methylation of primary miR-124-1 and primary miR-124-2 promoters (with no change in primary miR-124-3), resulting in turn to downregulated expression of both primary miR-124-1 and primary miR-124-2 as well as mature miR-124 in mouse primary microglial cells. The authors also examined the involvement of MECP2-STAT3 signaling in HIV-1-Tat-mediated microglial activation. Based on these novel findings, it is evident that dysregulation of miR-124 is involved in the pathogenesis of HAND and that restoration of miR-124 could serve as an adjunctive treatment for dampening neuroinflammation associated with HAND.

scholarly journals Epigenetic Promoter DNA Methylation of miR-124 Promotes HIV-1 Tat-Mediated Microglial Activation via MECP2-STAT3 Axis

2018 ◽  
Vol 38 (23) ◽  
pp. 5367-5383 ◽  
Author(s):  
Palsamy Periyasamy ◽  
Annadurai Thangaraj ◽  
Ming-Lei Guo ◽  
Guoku Hu ◽  
Shannon Callen ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Microglial Activation ◽  
Promoter Dna Methylation ◽  
Promoter Dna ◽  
Hiv 1

scholarly journals Inhibition of the Dead Box RNA Helicase 3 prevents HIV-1 Tat and cocaine-induced neurotoxicity by targeting microglia activation

2019 ◽  
Author(s):  
Marina Aksenova ◽  
Justin Sybrandt ◽  
Biyun Cui ◽  
Vitali Sikirzhytski ◽  
Hao Ji ◽  
...  
Keyword(s):  
Microglial Activation ◽  
Drugs Of Abuse ◽  
Viral Proteins ◽  
Rna Helicase ◽  
Literature Mining ◽  
Tat Protein ◽  
Mining System ◽  
Dead Box ◽  
Neuronal Toxicity ◽  
Hiv 1

AbstractHIV-1 Associated Neurocognitive Disorder (HAND) is commonly seen in HIV-infected patients. Viral proteins including Tat cause neuronal toxicity and is worsened by drugs of abuse. To uncover potential targets for anti-HAND therapy, we employed a literature mining system, MOLIERE. Here, we validated Dead Box RNA Helicase 3 (DDX3) as a target to treat HAND via a selective DDX3 inhibitor, RK-33. The combined neurotoxicity of Tat protein and cocaine was blocked by RK-33 in rat and mouse cortical cultures. Transcriptome analysis showed that Tat-activated transcripts include makers and regulators of microglial activation, and RK-33 blocked Tat-induced activation of these mRNAs. Elevated production of proinflammatory cytokines was also inhibited by RK-33. These findings show that DDX3 contributes to microglial activation triggered by Tat and cocaine, and DDX3 inhibition shows promise as a therapy for HAND. Moreover, DDX3 may contribute to the pathology of other neurodegenerative diseases with pathological activation of microglia.

scholarly journals Microglial HIV-1 Expression: Role in HIV-1 Associated Neurocognitive Disorders

Viruses ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 924
Author(s):  
Hailong Li ◽  
Kristen A. McLaurin ◽  
Jessica M. Illenberger ◽  
Charles F. Mactutus ◽  
Rosemarie M. Booze
Keyword(s):  
Distribution Pattern ◽  
Biological System ◽  
Neurocognitive Disorders ◽  
Cell Type ◽  
Viral Reservoirs ◽  
Major Cell Type ◽  
The Brain ◽  
Hiv 1

The persistence of HIV-1 viral reservoirs in the brain, despite treatment with combination antiretroviral therapy (cART), remains a critical roadblock for the development of a novel cure strategy for HIV-1. To enhance our understanding of viral reservoirs, two complementary studies were conducted to (1) evaluate the HIV-1 mRNA distribution pattern and major cell type expressing HIV-1 mRNA in the HIV-1 transgenic (Tg) rat, and (2) validate our findings by developing and critically testing a novel biological system to model active HIV-1 infection in the rat. First, a restricted, region-specific HIV-1 mRNA distribution pattern was observed in the HIV-1 Tg rat. Microglia were the predominant cell type expressing HIV-1 mRNA in the HIV-1 Tg rat. Second, we developed and critically tested a novel biological system to model key aspects of HIV-1 by infusing F344/N control rats with chimeric HIV (EcoHIV). In vitro, primary cultured microglia were treated with EcoHIV revealing prominent expression within 24 h of infection. In vivo, EcoHIV expression was observed seven days after stereotaxic injections. Following EcoHIV infection, microglia were the major cell type expressing HIV-1 mRNA, results that are consistent with observations in the HIV-1 Tg rat. Within eight weeks of infection, EcoHIV rats exhibited neurocognitive impairments and synaptic dysfunction, which may result from activation of the NogoA-NgR3/PirB-RhoA signaling pathway and/or neuroinflammation. Collectively, these studies enhance our understanding of HIV-1 viral reservoirs in the brain and offer a novel biological system to model HIV-associated neurocognitive disorders and associated comorbidities (i.e., drug abuse) in rats.

scholarly journals Calcitonin gene-related peptide regulates spinal microglial activation through the histone H3 lysine 27 trimethylation via enhancer of zeste homolog-2 in rats with neuropathic pain

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Qi An ◽  
Chenyan Sun ◽  
Ruidi Li ◽  
Shuhui Chen ◽  
Xinpei Gu ◽  
...  
Keyword(s):  
Neuropathic Pain ◽  
Dorsal Horn ◽  
Nerve Injury ◽  
Spinal Dorsal Horn ◽  
Microglial Activation ◽  
Microglial Cells ◽  
Gene Promoters ◽  
Spinal Dorsal ◽  
Related Peptide ◽  
Calcitonin Gene

Abstract Background Calcitonin gene-related peptide (CGRP) as a mediator of microglial activation at the transcriptional level may facilitate nociceptive signaling. Trimethylation of H3 lysine 27 (H3K27me3) by enhancer of zeste homolog 2 (EZH2) is an epigenetic mark that regulates inflammatory-related gene expression after peripheral nerve injury. In this study, we explored the relationship between CGRP and H3K27me3 in microglial activation after nerve injury, and elucidated the underlying mechanisms in the pathogenesis of chronic neuropathic pain. Methods Microglial cells (BV2) were treated with CGRP and differentially enrichments of H3K27me3 on gene promoters were examined using ChIP-seq. A chronic constriction injury (CCI) rat model was used to evaluate the role of CGRP on microglial activation and EZH2/H3K27me3 signaling in CCI-induced neuropathic pain. Results Overexpressions of EZH2 and H3K27me3 were confirmed in spinal microglia of CCI rats by immunofluorescence. CGRP treatment induced the increased of H3K27me3 expression in the spinal dorsal horn and cultured microglial cells (BV2) through EZH2. ChIP-seq data indicated that CGRP significantly altered H3K27me3 enrichments on gene promoters in microglia following CGRP treatment, including 173 gaining H3K27me3 and 75 losing this mark, which mostly enriched in regulation of cell growth, phagosome, and inflammation. qRT-PCR verified expressions of representative candidate genes (TRAF3IP2, BCL2L11, ITGAM, DAB2, NLRP12, WNT3, ADAM10) and real-time cell analysis (RTCA) verified microglial proliferation. Additionally, CGRP treatment and CCI increased expressions of ITGAM, ADAM10, MCP-1, and CX3CR1, key mediators of microglial activation in spinal dorsal horn and cultured microglial cells. Such increased effects induced by CCI were suppressed by CGRP antagonist and EZH2 inhibitor, which were concurrently associated with the attenuated mechanical and thermal hyperalgesia in CCI rats. Conclusion Our findings highly indicate that CGRP is implicated in the genesis of neuropathic pain through regulating microglial activation via EZH2-mediated H3K27me3 in the spinal dorsal horn.

scholarly journals Differential Effects of Toll-Like Receptor Activation and Differential Mediation by MAP Kinases of Immune Responses in Microglial Cells

2021 ◽  
Author(s):  
Jaedeok Kwon ◽  
Christos Arsenis ◽  
Maria Suessmilch ◽  
Alison McColl ◽  
Jonathan Cavanagh ◽  
...  
Keyword(s):  
Map Kinase ◽  
Microglial Activation ◽  
Map Kinases ◽  
Mrna Level ◽  
Cell Types ◽  
Receptor Activation ◽  
Microglial Cells ◽  
Toll Like Receptor ◽  
Disease States ◽  
Nitrite Production

AbstractMicroglial activation is believed to play a role in many psychiatric and neurodegenerative diseases. Based largely on evidence from other cell types, it is widely thought that MAP kinase (ERK, JNK and p38) signalling pathways contribute strongly to microglial activation following immune stimuli acting on toll-like receptor (TLR) 3 or TLR4. We report here that exposure of SimA9 mouse microglial cell line to immune mimetics stimulating TLR4 (lipopolysaccharide—LPS) or TLR7/8 (resiquimod/R848), results in marked MAP kinase activation, followed by induction of nitric oxide synthase, and various cytokines/chemokines. However, in contrast to TLR4 or TLR7/8 stimulation, very few effects of TLR3 stimulation by poly-inosine/cytidine (polyI:C) were detected. Induction of chemokines/cytokines at the mRNA level by LPS and resiquimod were, in general, only marginally affected by MAP kinase inhibition, and expression of TNF, Ccl2 and Ccl5 mRNAs, along with nitrite production, were enhanced by p38 inhibition in a stimulus-specific manner. Selective JNK inhibition enhanced Ccl2 and Ccl5 release. Many distinct responses to stimulation of TLR4 and TLR7 were observed, with JNK mediating TNF protein induction by the latter but not the former, and suppressing Ccl5 release by the former but not the latter. These data reveal complex modulation by MAP kinases of microglial responses to immune challenge, including a dampening of some responses. They demonstrate that abnormal levels of JNK or p38 signalling in microglial cells will perturb their profile of cytokine and chemokine release, potentially contributing to abnormal inflammatory patterns in CNS disease states.

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