Diversity of microglial transcriptional responses during opioid exposure and neuropathic pain

Microglia take on an altered morphology during chronic opioid treatment. This morphological change is broadly used to identify the activated microglial state associated with opioid side effects, including tolerance and opioid-induced hyperalgesia (OIH). Following chronic opioid treatment and peripheral nerve injury (PNI) microglia in the spinal cord display similar morphological responses. Consistent with this observation, functional studies have suggested that microglia activated by PNI or opioids engage common molecular mechanisms to induce hypersensitivity. Here we conducted deep RNA sequencing of acutely isolated spinal cord microglia from male mice to comprehensively interrogate transcriptional states and mechanistic commonality between multiple OIH and PNI models. Following PNI, we identify a common early proliferative transcriptional event across models that precedes the upregulation of histological markers of activation, followed by a delayed and injury-specific transcriptional response. Strikingly, we found no such transcriptional responses associated with opioid-induced microglial activation, consistent with histological data indicating that microglia number remain stable during morphine treatment. Collectively, these results reveal the diversity of pain-associated microglial transcriptomes and point towards the targeting of distinct insult-specific microglial responses to treat OIH, PNI, or other CNS pathologies.

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α2δ-1–Bound N-Methyl-d-aspartate Receptors Mediate Morphine-induced Hyperalgesia and Analgesic Tolerance by Potentiating Glutamatergic Input in Rodents

Anesthesiology ◽

10.1097/aln.0000000000002648 ◽

2019 ◽

Vol 130 (5) ◽

pp. 804-819 ◽

Cited By ~ 5

Author(s):

Meichun Deng ◽

Shao-Rui Chen ◽

Hong Chen ◽

Hui-Lin Pan

Keyword(s):

Spinal Cord ◽

Spinal Dorsal Horn ◽

Receptor Activity ◽

Morphine Treatment ◽

Chronic Morphine ◽

Analgesic Tolerance ◽

Spinal Dorsal ◽

Aspartate Receptor ◽

C Terminus ◽

Opioid Induced Hyperalgesia

Abstract Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New Background Chronic use of μ-opioid receptor agonists paradoxically causes both hyperalgesia and the loss of analgesic efficacy. Opioid treatment increases presynaptic N-methyl-d-aspartate receptor activity to potentiate nociceptive input to spinal dorsal horn neurons. However, the mechanism responsible for this opioid-induced activation of presynaptic N-methyl-d-aspartate receptors remains unclear. α2δ-1, formerly known as a calcium channel subunit, interacts with N-methyl-d-aspartate receptors and is primarily expressed at presynaptic terminals. This study tested the hypothesis that α2δ-1–bound N-methyl-d-aspartate receptors contribute to presynaptic N-methyl-d-aspartate receptor hyperactivity associated with opioid-induced hyperalgesia and analgesic tolerance. Methods Rats (5 mg/kg) and wild-type and α2δ-1–knockout mice (10 mg/kg) were treated intraperitoneally with morphine twice/day for 8 consecutive days, and nociceptive thresholds were examined. Presynaptic N-methyl-d-aspartate receptor activity was recorded in spinal cord slices. Coimmunoprecipitation was performed to examine protein–protein interactions. Results Chronic morphine treatment in rats increased α2δ-1 protein amounts in the dorsal root ganglion and spinal cord. Chronic morphine exposure also increased the physical interaction between α2δ-1 and N-methyl-d-aspartate receptors by 1.5 ± 0.3 fold (means ± SD, P = 0.009, n = 6) and the prevalence of α2δ-1–bound N-methyl-d-aspartate receptors at spinal cord synapses. Inhibiting α2δ-1 with gabapentin or genetic knockout of α2δ-1 abolished the increase in presynaptic N-methyl-d-aspartate receptor activity in the spinal dorsal horn induced by morphine treatment. Furthermore, uncoupling the α2δ-1–N-methyl-d-aspartate receptor interaction with an α2δ-1 C terminus–interfering peptide fully reversed morphine-induced tonic activation of N-methyl-d-aspartate receptors at the central terminal of primary afferents. Finally, intraperitoneal injection of gabapentin or intrathecal injection of an α2δ-1 C terminus–interfering peptide or α2δ-1 genetic knockout abolished the mechanical and thermal hyperalgesia induced by chronic morphine exposure and largely preserved morphine’s analgesic effect during 8 days of morphine treatment. Conclusions α2δ-1–Bound N-methyl-d-aspartate receptors contribute to opioid-induced hyperalgesia and tolerance by augmenting presynaptic N-methyl-d-aspartate receptor expression and activity at the spinal cord level.

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Mesenchymal Stem Cells Reversed Morphine Tolerance and Opioid-induced Hyperalgesia

Scientific Reports ◽

10.1038/srep32096 ◽

2016 ◽

Vol 6 (1) ◽

Cited By ~ 18

Author(s):

Zhen Hua ◽

LiPing Liu ◽

Jun Shen ◽

Kathleen Cheng ◽

Aijun Liu ◽

...

Keyword(s):

Spinal Cord ◽

Stem Cells ◽

Mesenchymal Stem Cells ◽

Morphine Tolerance ◽

Opioid Therapy ◽

Morphine Treatment ◽

Activation Level ◽

The Us ◽

Opioid Induced Hyperalgesia ◽

Rats And Mice

Abstract More than 240 million opioid prescriptions are dispensed annually to treat pain in the US. The use of opioids is commonly associated with opioid tolerance (OT) and opioid-induced hyperalgesia (OIH), which limit efficacy and compromise safety. The dearth of effective way to prevent or treat OT and OIH is a major medical challenge. We hypothesized that mesenchymal stem cells (MSCs) attenuate OT and OIH in rats and mice based on the understanding that MSCs possess remarkable anti-inflammatory properties and that both OT and chronic pain are associated with neuroinflammation in the spinal cord. We found that the development of OT and OIH was effectively prevented by either intravenous or intrathecal MSC transplantation (MSC-TP), which was performed before morphine treatment. Remarkably, established OT and OIH were significantly reversed by either intravenous or intrathecal MSCs when cells were transplanted after repeated morphine injections. The animals did not show any abnormality in vital organs or functions. Immunohistochemistry revealed that the treatments significantly reduced activation level of microglia and astrocytes in the spinal cord. We have thus demonstrated that MSC-TP promises to be a potentially safe and effective way to prevent and reverse two of the major problems of opioid therapy.

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Permissive epigenetic landscape facilitates distinct transcriptional signatures of activating transcription factor 6 in the liver

10.1101/2021.03.10.434889 ◽

2021 ◽

Author(s):

Anjana Ramdas Nair ◽

Priyanka Lakhiani ◽

Chi Zhang ◽

Filippo Macchi ◽

Kirsten C. Sadler

Keyword(s):

Transcription Factor ◽

Target Genes ◽

Expression Patterns ◽

Transcriptional Response ◽

Differentially Expressed ◽

Small Subset ◽

Gene Promoters ◽

Transcriptional Responses ◽

Functional Studies ◽

Activating Transcription Factor

ABSTRACTProteostatic stress initiates a transcriptional response that is unique to the stress condition, yet the regulatory mechanisms underlying the distinct gene expression patterns observed in stressed cells remains unknown. Using a functional genomic approach, we investigated how activating transcription factor 6 (ATF6), a key transcription factor in the unfolded protein response (UPR), regulates target genes. We first designed a computational strategy to define Atf6 target genes based on the evolutionary conservation of predicted ATF6 binding in gene promoters, identifying 652 conserved putative Atf6 target (CPAT) genes. CPATs were overrepresented for genes functioning in the UPR, however, the majority functioned in cellular processes unrelated to proteostasis, including small molecule metabolism and development. Functional studies of stress-independent and toxicant based Atf6 activation in zebrafish livers showed that the pattern of CPAT expression in response to Atf6 overexpression, alcohol and arsenic was unique. Only 34 CPATs were differentially expressed in all conditions, indicating that Atf6 is sufficient to regulate a small subset of CPATs. Blocking Atf6 using Ceapins in zebrafish demonstrated that Atf6 is necessary for activation of these genes in response to arsenic. We investigated CPAT during physiologically mediated hepatocyte stress using liver regeneration in mice as a model. Over half of all CPATs were differentially expressed during this process. This was attributed to the permissive chromatin environment in quiescent livers on the promoters of these genes, characterized by the absence of H3K27me3 and enrichment of H3K4me3. Taken together, these data uncover a complex transcriptional response to Atf6 activation and implicate a permissive epigenome as a mechanism by which distinct transcriptional responses are regulated by Atf6.

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Sex Differences in Liver, Adipose Tissue, and Muscle Transcriptional Response to Fasting and Refeeding in Mice

Cells ◽

10.3390/cells8121529 ◽

2019 ◽

Vol 8 (12) ◽

pp. 1529

Author(s):

Nadezhda Bazhan ◽

Tatiana Jakovleva ◽

Natalia Feofanova ◽

Elena Denisova ◽

Anastasia Dubinina ◽

...

Keyword(s):

Gene Expression ◽

Molecular Mechanisms ◽

Metabolic Response ◽

Transcriptional Response ◽

Acid Oxidation ◽

Refeeding Syndrome ◽

Transcriptional Responses ◽

Hepatic Expression ◽

Fasting And Refeeding ◽

Sex Asymmetry

Fasting is often used for obesity correction but the “refeeding syndrome” limits its efficiency, and molecular mechanisms underlying metabolic response to different food availability are under investigation. Sex was shown to affect hormonal and metabolic reactions to fasting/refeeding. The aim of this study was to evaluate hormonal and transcriptional responses to fasting and refeeding in male and female C57Bl/6J mice. Sex asymmetry was observed both at the hormonal and transcriptional levels. Fasting (24 h) induced increase in hepatic Fgf21 gene expression, which was associated with elevation of plasma FGF21 and adiponectin levels, and the upregulation of expression of hepatic (Pparα, Cpt1α) and muscle (Cpt1β, Ucp3) genes involved in fatty acid oxidation. These changes were more pronounced in females. Refeeding (6 h) evoked hyperinsulinemia and increased hepatic expression of gene related to lipogenesis (Fasn) only in males and hyperleptinemia and increase in Fgf21 gene expression in muscles and adipose tissues only in females. The results suggest that in mice, one of the molecular mechanisms underlying sex asymmetry in hepatic Pparα, Cpt1α, muscle Cpt1β, and Ucp3 expression during fasting is hepatic Fgf21 expression, and the reason for sex asymmetry in hepatic Fasn expression during refeeding is male-specific hyperinsulinemia.

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Gene transcription and chromatin regulation in hypoxia

Biochemical Society Transactions ◽

10.1042/bst20191106 ◽

2020 ◽

Vol 48 (3) ◽

pp. 1121-1128 ◽

Cited By ~ 1

Author(s):

Michael Batie ◽

Sonia Rocha

Keyword(s):

Molecular Mechanisms ◽

Essential Feature ◽

Hypoxia Inducible Factor ◽

Transcriptional Response ◽

Dependent Manner ◽

Transcriptional Responses ◽

Oxygen Homeostasis ◽

Expression Control ◽

Gene Expression Control ◽

Key Players

Oxygen sensing is an essential feature of metazoan biology and reductions in oxygen availability (hypoxia) have both physiological and pathophysiological implications. Co-ordinated mechanisms have evolved for sensing and responding to hypoxia, which involve diverse biological outputs, with the main aim of restoring oxygen homeostasis. This includes a dynamic gene transcriptional response, the central drivers of which are the hypoxia-inducible factor (HIF) family of transcription factors. HIFs are regulated in an oxygen-dependent manner and while their role in hypoxia is well established, it is apparent that other key players are required for gene expression control in hypoxia. In this review, we highlight the current understanding of the known and potential molecular mechanisms underpinning gene transcriptional responses to hypoxia in mammals, with a focus on oxygen-dependent effects on chromatin structure.

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High Altitude hypoxia

Current Proteomics ◽

10.2174/1570164617999201002144747 ◽

2020 ◽

Vol 17 ◽

Author(s):

Asma Babar ◽

Kifayatullah Mengal ◽

Abdul Hanan Babar ◽

Shixin Wu ◽

Mujahid Ali Shah ◽

...

Keyword(s):

Protein Synthesis ◽

High Altitude ◽

Molecular Mechanisms ◽

Strong Association ◽

Haemoglobin Concentration ◽

Metabolic Reprogramming ◽

Molecular Networks ◽

Whole Genome ◽

Gene Expressions ◽

Transcriptional Responses

: The world highest and largest altitude area is called the Qinghai-Tibetan plateau (QTB), which harbors unique animal and plant species. Mammals that inhabit the higher altitude regions have adapted well to the hypoxic conditions. One of the main stressors at high altitude is hypoxia. Metabolic responses to hypoxia play important roles in cell survival strategies and some diseases. However, the homeostatic alterations that equilibrate variations in the demand and supply of energy to maintain organismal function in a prolonged low O2 environment persist partly understood, making it problematic to differentiate adaptive from maladaptive responses in hypoxia. Tibetans and yaks are two perfect examples innate to the plateau for high altitude adaptation. By the scan of the whole-genome, EPAS1 and EGLN1 were identified as key genes associated with sustained haemoglobin concentration in high altitude mammals for adaptation. The yak is a much more ancient mammal which has existed on QTB longer than humans, it is, therefore, possible that natural selection represented a diverse group of genes/pathways in yaks. Physiological characteristics are extremely informative in revealing molecular networks associated with inherited adaptation, in addition to the whole-genome adaptive changes at the DNA sequence level. Gene-expression can be changed by a variety of signals originating from the environment, and hypoxia is the main factor amongst them. The hypoxia-inducible factors (HIF-1α and EPAS1/HIF-2α) are the main regulators of oxygen in homeostasis which play a role as maestro regulators of adaptation in hypoxic reaction of molecular mechanisms. (Vague) The basis of this review is to present recent information regarding the molecular mechanism involved in hypoxia that regulates candidate genes and proteins. Many transcriptional responses toward hypoxia are facilitated by HIFs that change the number of gene expressions and help in angiogenesis, erythropoiesis, metabolic reprogramming and metastasis. HIFs also activate several signals highlighting a strong association between hypoxia, the misfolded proteins’ accumulation in the endoplasmic reticulum in stress and activation of unfolded protein response (UPR). It was observed that at high-altitude, pregnancies yield a low birth weight ∼100 g per1000 m of the climb. (Vague) It may involve variation in the events of energy-demanding, like protein synthesis. Prolonged hypobaric hypoxia causes placental ER stress, which in turn, moderates protein synthesis and reduces proliferation. Further, Cardiac hypertrophy by cytosolic Ca2+ raises and Ca2+/calmodulin, calcineurin stimulation, NF-AT3 pathway might be caused by an imbalance in Sarcoplasmic reticulum ER Ca2, might be adaptive in beginning but severe later.

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Examination of the Transcriptional Response to LaMIR166a Overexpression in Larix kaempferi (Lamb.) Carr

Biology ◽

10.3390/biology10070576 ◽

2021 ◽

Vol 10 (7) ◽

pp. 576

Author(s):

Yanru Fan ◽

Wanfeng Li ◽

Zhexin Li ◽

Shaofei Dang ◽

Suying Han ◽

...

Keyword(s):

Cell Lines ◽

Molecular Mechanisms ◽

Target Genes ◽

De Novo ◽

Pearson Correlation ◽

Transcriptional Response ◽

Correlation Coefficients ◽

Embryonic Cell ◽

Larix Kaempferi ◽

Transgenic Cell

The study of somatic embryogenesis can provide insight into early plant development. We previously obtained LaMIR166a-overexpressing embryonic cell lines of Larix kaempferi (Lamb.) Carr. To further elucidate the molecular mechanisms associated with miR166 in this species, the transcriptional profiles of wild-type (WT) and three LaMIR166a-overexpressing transgenic cell lines were subjected to RNA sequencing using the Illumina NovaSeq 6000 system. In total, 203,256 unigenes were generated using Trinity de novo assembly, and 2467 differentially expressed genes were obtained by comparing transgenic and WT lines. In addition, we analyzed the cleaved degree of LaMIR166a target genes LaHDZ31–34 in different transgenic cell lines by detecting the expression pattern of LaHdZ31–34, and their cleaved degree in transgenic cell lines was higher than that in WT. The downstream genes of LaHDZ31–34 were identified using Pearson correlation coefficients. Yeast one-hybrid and dual-luciferase report assays revealed that the transcription factors LaHDZ31–34 could bind to the promoters of LaPAP, LaPP1, LaZFP5, and LaPHO1. This is the first report of gene expression changes caused by LaMIR166a overexpression in Japanese larch. These findings lay a foundation for future studies on the regulatory mechanism of miR166.

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Fibrillar α-synuclein induces neurotoxic astrocyte activation via RIP kinase signaling and NF-κB

Cell Death and Disease ◽

10.1038/s41419-021-04049-0 ◽

2021 ◽

Vol 12 (8) ◽

Author(s):

Tsui-Wen Chou ◽

Nydia P. Chang ◽

Medha Krishnagiri ◽

Aisha P. Patel ◽

Marissa Lindman ◽

...

Keyword(s):

Cell Death ◽

Cell Biology ◽

Molecular Mechanisms ◽

Neurodegenerative Disorder ◽

Neuronal Cell ◽

Dopamine Neurons ◽

Functional Markers ◽

Kinase Signaling ◽

Astrocyte Activation ◽

Transcriptional Responses

AbstractParkinson’s disease (PD) is a neurodegenerative disorder characterized by the death of midbrain dopamine neurons. The pathogenesis of PD is poorly understood, though misfolded and/or aggregated forms of the protein α-synuclein have been implicated in several neurodegenerative disease processes, including neuroinflammation and astrocyte activation. Astrocytes in the midbrain play complex roles during PD, initiating both harmful and protective processes that vary over the course of the disease. However, despite their significant regulatory roles during neurodegeneration, the cellular and molecular mechanisms that promote pathogenic astrocyte activity remain mysterious. Here, we show that α-synuclein preformed fibrils (PFFs) induce pathogenic activation of human midbrain astrocytes, marked by inflammatory transcriptional responses, downregulation of phagocytic function, and conferral of neurotoxic activity. These effects required the necroptotic kinases RIPK1 and RIPK3, but were independent of MLKL and necroptosis. Instead, both transcriptional and functional markers of astrocyte activation occurred via RIPK-dependent activation of NF-κB signaling. Our study identifies a previously unknown function for α-synuclein in promoting neurotoxic astrocyte activation, as well as new cell death-independent roles for RIP kinase signaling in the regulation of glial cell biology and neuroinflammation. Together, these findings highlight previously unappreciated molecular mechanisms of pathologic astrocyte activation and neuronal cell death with implications for Parkinsonian neurodegeneration.

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Tumor hypoxia induces nuclear paraspeckle formation through HIF-2α dependent transcriptional activation of NEAT1 leading to cancer cell survival

Oncogene ◽

10.1038/onc.2014.378 ◽

2014 ◽

Vol 34 (34) ◽

pp. 4482-4490 ◽

Cited By ~ 118

Author(s):

H Choudhry ◽

A Albukhari ◽

M Morotti ◽

S Haider ◽

D Moralli ◽

...

Keyword(s):

Breast Cancer ◽

Cancer Cell ◽

Transcriptional Activation ◽

Cellular Proliferation ◽

Hypoxia Inducible Factor ◽

Tumor Hypoxia ◽

Transcriptional Response ◽

Clonogenic Survival ◽

Breast Cancer Cell Lines ◽

Transcriptional Responses

Abstract Activation of cellular transcriptional responses, mediated by hypoxia-inducible factor (HIF), is common in many types of cancer, and generally confers a poor prognosis. Known to induce many hundreds of protein-coding genes, HIF has also recently been shown to be a key regulator of the non-coding transcriptional response. Here, we show that NEAT1 long non-coding RNA (lncRNA) is a direct transcriptional target of HIF in many breast cancer cell lines and in solid tumors. Unlike previously described lncRNAs, NEAT1 is regulated principally by HIF-2 rather than by HIF-1. NEAT1 is a nuclear lncRNA that is an essential structural component of paraspeckles and the hypoxic induction of NEAT1 induces paraspeckle formation in a manner that is dependent upon both NEAT1 and on HIF-2. Paraspeckles are multifunction nuclear structures that sequester transcriptionally active proteins as well as RNA transcripts that have been subjected to adenosine-to-inosine (A-to-I) editing. We show that the nuclear retention of one such transcript, F11R (also known as junctional adhesion molecule 1, JAM1), in hypoxia is dependent upon the hypoxic increase in NEAT1, thereby conferring a novel mechanism of HIF-dependent gene regulation. Induction of NEAT1 in hypoxia also leads to accelerated cellular proliferation, improved clonogenic survival and reduced apoptosis, all of which are hallmarks of increased tumorigenesis. Furthermore, in patients with breast cancer, high tumor NEAT1 expression correlates with poor survival. Taken together, these results indicate a new role for HIF transcriptional pathways in the regulation of nuclear structure and that this contributes to the pro-tumorigenic hypoxia-phenotype in breast cancer.

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Beyond the lesion site: minocycline augments inflammation and anxiety-like behavior following SCI in rats through action on the gut microbiota

Journal of Neuroinflammation ◽

10.1186/s12974-021-02123-0 ◽

2021 ◽

Vol 18 (1) ◽

Author(s):

Emma K. A. Schmidt ◽

Pamela J. F. Raposo ◽

Abel Torres-Espin ◽

Keith K. Fenrich ◽

Karim Fouad

Keyword(s):

Spinal Cord ◽

Central Nervous System ◽

Spinal Cord Injury ◽

Nervous System ◽

Gut Microbiota ◽

Microglial Activation ◽

Motor Recovery ◽

Long Term Effects ◽

Cord Injury ◽

Anti Inflammatory

Abstract Background Minocycline is a clinically available synthetic tetracycline derivative with anti-inflammatory and antibiotic properties. The majority of studies show that minocycline can reduce tissue damage and improve functional recovery following central nervous system injuries, mainly attributed to the drug’s direct anti-inflammatory, anti-oxidative, and neuroprotective properties. Surprisingly the consequences of minocycline’s antibiotic (i.e., antibacterial) effects on the gut microbiota and systemic immune response after spinal cord injury have largely been ignored despite their links to changes in mental health and immune suppression. Methods Here, we sought to determine minocycline’s effect on spinal cord injury-induced changes in the microbiota-immune axis using a cervical contusion injury in female Lewis rats. We investigated a group that received minocycline following spinal cord injury (immediately after injury for 7 days), an untreated spinal cord injury group, an untreated uninjured group, and an uninjured group that received minocycline. Plasma levels of cytokines/chemokines and fecal microbiota composition (using 16s rRNA sequencing) were monitored for 4 weeks following spinal cord injury as measures of the microbiota-immune axis. Additionally, motor recovery and anxiety-like behavior were assessed throughout the study, and microglial activation was analyzed immediately rostral to, caudal to, and at the lesion epicenter. Results We found that minocycline had a profound acute effect on the microbiota diversity and composition, which was paralleled by the subsequent normalization of spinal cord injury-induced suppression of cytokines/chemokines. Importantly, gut dysbiosis following spinal cord injury has been linked to the development of anxiety-like behavior, which was also decreased by minocycline. Furthermore, although minocycline attenuated spinal cord injury-induced microglial activation, it did not affect the lesion size or promote measurable motor recovery. Conclusion We show that minocycline’s microbiota effects precede its long-term effects on systemic cytokines and chemokines following spinal cord injury. These results provide an exciting new target of minocycline as a therapeutic for central nervous system diseases and injuries.

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