Publications by authors named "Nathaniel S Woodling"

23 Publications

  • Page 1 of 1

Cell type-specific modulation of healthspan by Forkhead family transcription factors in the nervous system.

Proc Natl Acad Sci U S A 2021 Feb;118(8)

Institute of Healthy Ageing, University College London, London WC1E 6BT, United Kingdom;

Reduced activity of insulin/insulin-like growth factor signaling (IIS) increases healthy lifespan among diverse animal species. Downstream of IIS, multiple evolutionarily conserved transcription factors (TFs) are required; however, distinct TFs are likely responsible for these effects in different tissues. Here we have asked which TFs can extend healthy lifespan within distinct cell types of the adult nervous system in Starting from published single-cell transcriptomic data, we report that (FKH) is endogenously expressed in neurons, whereas (FOXO) is expressed in glial cells. Accordingly, we find that neuronal FKH and glial FOXO exert independent prolongevity effects. We have further explored the role of neuronal FKH in a model of Alzheimer's disease-associated neuronal dysfunction, where we find that increased neuronal FKH preserves behavioral function and reduces ubiquitinated protein aggregation. Finally, using transcriptomic profiling, we identify , a member of the Atg1 autophagy initiation family, as one FKH-dependent target whose neuronal overexpression is sufficient to extend healthy lifespan. Taken together, our results underscore the importance of cell type-specific mapping of TF activity to preserve healthy function with age.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1073/pnas.2011491118DOI Listing
February 2021

Fine-tuning autophagy maximises lifespan and is associated with changes in mitochondrial gene expression in Drosophila.

PLoS Genet 2020 11 30;16(11):e1009083. Epub 2020 Nov 30.

Institute of Healthy Ageing, Research Department of Genetics, Evolution and Environment, University College London, London, United Kingdom.

Increased cellular degradation by autophagy is a feature of many interventions that delay ageing. We report here that increased autophagy is necessary for reduced insulin-like signalling (IIS) to extend lifespan in Drosophila and is sufficient on its own to increase lifespan. We first established that the well-characterised lifespan extension associated with deletion of the insulin receptor substrate chico was completely abrogated by downregulation of the essential autophagy gene Atg5. We next directly induced autophagy by over-expressing the major autophagy kinase Atg1 and found that a mild increase in autophagy extended lifespan. Interestingly, strong Atg1 up-regulation was detrimental to lifespan. Transcriptomic and metabolomic approaches identified specific signatures mediated by varying levels of autophagy in flies. Transcriptional upregulation of mitochondrial-related genes was the signature most specifically associated with mild Atg1 upregulation and extended lifespan, whereas short-lived flies, possessing strong Atg1 overexpression, showed reduced mitochondrial metabolism and up-regulated immune system pathways. Increased proteasomal activity and reduced triacylglycerol levels were features shared by both moderate and high Atg1 overexpression conditions. These contrasting effects of autophagy on ageing and differential metabolic profiles highlight the importance of fine-tuning autophagy levels to achieve optimal healthspan and disease prevention.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1371/journal.pgen.1009083DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7738165PMC
November 2020

Independent glial subtypes delay development and extend healthy lifespan upon reduced insulin-PI3K signalling.

BMC Biol 2020 09 14;18(1):124. Epub 2020 Sep 14.

Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, London, WC1E 6BT, UK.

Background: The increasing age of global populations highlights the urgent need to understand the biological underpinnings of ageing. To this end, inhibition of the insulin/insulin-like signalling (IIS) pathway can extend healthy lifespan in diverse animal species, but with trade-offs including delayed development. It is possible that distinct cell types underlie effects on development and ageing; cell-type-specific strategies could therefore potentially avoid negative trade-offs when targeting diseases of ageing, including prevalent neurodegenerative diseases. The highly conserved diversity of neuronal and non-neuronal (glial) cell types in the Drosophila nervous system makes it an attractive system to address this possibility. We have thus investigated whether IIS in distinct glial cell populations differentially modulates development and lifespan in Drosophila.

Results: We report here that glia-specific IIS inhibition, using several genetic means, delays development while extending healthy lifespan. The effects on lifespan can be recapitulated by adult-onset IIS inhibition, whereas developmental IIS inhibition is dispensable for modulation of lifespan. Notably, the effects we observe on both lifespan and development act through the PI3K branch of the IIS pathway and are dependent on the transcription factor FOXO. Finally, IIS inhibition in several glial subtypes can delay development without extending lifespan, whereas the same manipulations in astrocyte-like glia alone are sufficient to extend lifespan without altering developmental timing.

Conclusions: These findings reveal a role for distinct glial subpopulations in the organism-wide modulation of development and lifespan, with IIS in astrocyte-like glia contributing to lifespan modulation but not to developmental timing. Our results enable a more complete picture of the cell-type-specific effects of the IIS network, a pathway whose evolutionary conservation in humans make it tractable for therapeutic interventions. Our findings therefore underscore the necessity for cell-type-specific strategies to optimise interventions for the diseases of ageing.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12915-020-00854-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7490873PMC
September 2020

PICALM rescues glutamatergic neurotransmission, behavioural function and survival in a Drosophila model of Aβ42 toxicity.

Hum Mol Genet 2020 Aug;29(14):2420-2434

Department of Genetics, Evolution and Environment, Institute of Healthy Ageing, University College London, London WC1E 6BT, UK.

Alzheimer's disease (AD) is the most common form of dementia and the most prevalent neurodegenerative disease. Genome-wide association studies have linked PICALM to AD risk. PICALM has been implicated in Aβ42 production and turnover, but whether it plays a direct role in modulating Aβ42 toxicity remains unclear. We found that increased expression of the Drosophila PICALM orthologue lap could rescue Aβ42 toxicity in an adult-onset model of AD, without affecting Aβ42 level. Imbalances in the glutamatergic system, leading to excessive, toxic stimulation, have been associated with AD. We found that Aβ42 caused the accumulation of presynaptic vesicular glutamate transporter (VGlut) and increased spontaneous glutamate release. Increased lap expression reversed these phenotypes back to control levels, suggesting that lap may modulate glutamatergic transmission. We also found that lap modulated the localization of amphiphysin (Amph), the homologue of another AD risk factor BIN1, and that Amph itself modulated postsynaptic glutamate receptor (GluRII) localization. We propose a model where PICALM modulates glutamatergic transmission, together with BIN1, to ameliorate synaptic dysfunction and disease progression.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/hmg/ddaa125DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7424762PMC
August 2020

The neuronal receptor tyrosine kinase Alk is a target for longevity.

Aging Cell 2020 05 15;19(5):e13137. Epub 2020 Apr 15.

Department of Genetics, Evolution and Environment, Institute of Healthy Ageing, University College London, London, UK.

Inhibition of signalling through several receptor tyrosine kinases (RTKs), including the insulin-like growth factor receptor and its orthologues, extends healthy lifespan in organisms from diverse evolutionary taxa. This raises the possibility that other RTKs, including those already well studied for their roles in cancer and developmental biology, could be promising targets for extending healthy lifespan. Here, we focus on anaplastic lymphoma kinase (Alk), an RTK with established roles in nervous system development and in multiple cancers, but whose effects on aging remain unclear. We find that several means of reducing Alk signalling, including mutation of its ligand jelly belly (jeb), RNAi knock-down of Alk, or expression of dominant-negative Alk in adult neurons, can extend healthy lifespan in female, but not male, Drosophila. Moreover, reduced Alk signalling preserves neuromuscular function with age, promotes resistance to starvation and xenobiotic stress, and improves night sleep consolidation. We find further that inhibition of Alk signalling in adult neurons modulates the expression of several insulin-like peptides, providing a potential mechanistic link between neuronal Alk signalling and organism-wide insulin-like signalling. Finally, we show that TAE-684, a small molecule inhibitor of Alk, can extend healthy lifespan in Drosophila, suggesting that the repurposing of Alk inhibitors may be a promising direction for strategies to promote healthy aging.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/acel.13137DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7253064PMC
May 2020

Shifting equilibriums in Alzheimer's disease: the complex roles of microglia in neuroinflammation, neuronal survival and neurogenesis.

Neural Regen Res 2020 Jul;15(7):1208-1219

Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, London, UK.

Alzheimer's disease is the leading cause of dementia. Its increased prevalence in developed countries, due to the sharp rise in ageing populations, presents one of the costliest challenges to modern medicine. In order to find disease-modifying therapies to confront this challenge, a more complete understanding of the pathogenesis of Alzheimer's disease is necessary. Recent studies have revealed increasing evidence for the roles played by microglia, the resident innate immune system cells of the brain. Reflecting the well-established roles of microglia in reacting to pathogens and inflammatory stimuli, there is now a growing literature describing both protective and detrimental effects for individual cytokines and chemokines produced by microglia in Alzheimer's disease. A smaller but increasing number of studies have also addressed the divergent roles played by microglial neurotrophic and neurogenic factors, and how their perturbation may play a key role in the pathogenesis of Alzheimer's disease. Here we review recent findings on the roles played by microglia in neuroinflammation, neuronal survival and neurogenesis in Alzheimer's disease. In each case, landmark studies have provided evidence for the divergent ways in which microglia can either promote neuronal function and survival, or perturb neuronal function, leading to cell death. In many cases, the secreted molecules of microglia can lead to divergent effects depending on the magnitude and context of microglial activation. This suggests that microglial functions must be maintained in a fine equilibrium, in order to support healthy neuronal function, and that the cellular microenvironment in the Alzheimer's disease brain disrupts this fine balance, leading to neurodegeneration. Thus, an understanding of microglial homeostasis, both in health and across the trajectory of the disease state, will improve our understanding of the pathogenic mechanisms underlying Alzheimer's disease, and will hopefully lead to the development of microglial-based therapeutic strategies to restore equilibrium in the Alzheimer's disease brain.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4103/1673-5374.272571DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7047786PMC
July 2020

Parkinson's Disease: Mitochondria Parked at the ER Hit the Snooze Button.

Neuron 2018 06;98(6):1059-1061

Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, Darwin Building, Gower Street, London WC1E 6BT, UK; Max Planck Institute for Biology of Ageing, Joseph-Stelzmann-Strasse 9b, 50931 Cologne, Germany. Electronic address:

Parkinson's disease patients report sleep disturbances well ahead of motor symptoms. In this issue of Neuron, Valadas et al. (2018) report that the disease genes pink1 and parkin exert novel, cell-type-specific effects to modulate ER-mitochondria contacts, neuropeptidergic transmission, and sleep patterns.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.neuron.2018.06.025DOI Listing
June 2018

Deficiency in Neuronal TGF-β Signaling Leads to Nigrostriatal Degeneration and Activation of TGF-β Signaling Protects against MPTP Neurotoxicity in Mice.

J Neurosci 2017 04 31;37(17):4584-4592. Epub 2017 Mar 31.

Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California 94305, and

Transforming growth factor-β (TGF-β) plays an important role in the development and maintenance of embryonic dopaminergic (DA) neurons in the midbrain. To study the function of TGF-β signaling in the adult nigrostriatal system, we generated transgenic mice with reduced TGF-β signaling in mature neurons. These mice display age-related motor deficits and degeneration of the nigrostriatal system. Increasing TGF-β signaling in the substantia nigra through adeno-associated virus expressing a constitutively active type I receptor significantly reduces 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced dopaminergic neurodegeneration and motor deficits. These results suggest that TGF-β signaling is critical for adult DA neuron survival and that modulating this signaling pathway has therapeutic potential in Parkinson disease. We show that reducing Transforming growth factor-β (TGF-β) signaling promotes Parkinson disease-related pathologies and motor deficits, and increasing TGF-β signaling reduces neurotoxicity of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, a parkinsonism-inducing agent. Our results provide a rationale to pursue a means of increasing TGF-β signaling as a potential therapy for Parkinson's disease.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1523/JNEUROSCI.2952-16.2017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5413189PMC
April 2017

A Drosophila Model of Neuronopathic Gaucher Disease Demonstrates Lysosomal-Autophagic Defects and Altered mTOR Signalling and Is Functionally Rescued by Rapamycin.

J Neurosci 2016 11;36(46):11654-11670

Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, United Kingdom,

Glucocerebrosidase (GBA1) mutations are associated with Gaucher disease (GD), an autosomal recessive disorder caused by functional deficiency of glucocerebrosidase (GBA), a lysosomal enzyme that hydrolyzes glucosylceramide to ceramide and glucose. Neuronopathic forms of GD can be associated with rapid neurological decline (Type II) or manifest as a chronic form (Type III) with a wide spectrum of neurological signs. Furthermore, there is now a well-established link between GBA1 mutations and Parkinson's disease (PD), with heterozygote mutations in GBA1 considered the commonest genetic defect in PD. Here we describe a novel Drosophila model of GD that lacks the two fly GBA1 orthologs. This knock-out model recapitulates the main features of GD at the cellular level with severe lysosomal defects and accumulation of glucosylceramide in the fly brain. We also demonstrate a block in autophagy flux in association with reduced lifespan, age-dependent locomotor deficits and accumulation of autophagy substrates in dGBA-deficient fly brains. Furthermore, mechanistic target of rapamycin (mTOR) signaling is downregulated in dGBA knock-out flies, with a concomitant upregulation of Mitf gene expression, the fly ortholog of mammalian TFEB, likely as a compensatory response to the autophagy block. Moreover, the mTOR inhibitor rapamycin is able to partially ameliorate the lifespan, locomotor, and oxidative stress phenotypes. Together, our results demonstrate that this dGBA1-deficient fly model is a useful platform for the further study of the role of lysosomal-autophagic impairment and the potential therapeutic benefits of rapamycin in neuronopathic GD. These results also have important implications for the role of autophagy and mTOR signaling in GBA1-associated PD SIGNIFICANCE STATEMENT: We developed a Drosophila model of neuronopathic GD by knocking-out the fly orthologs of the GBA1 gene, demonstrating abnormal lysosomal pathology in the fly brain. Functioning lysosomes are required for autophagosome-lysosomal fusion in the autophagy pathway. We show in vivo that autophagy is impaired in dGBA-deficient fly brains. In response, mechanistic target of rapamycin (mTOR) activity is downregulated in dGBA-deficient flies and rapamycin ameliorates the lifespan, locomotor, and oxidative stress phenotypes. dGBA knock-out flies also display an upregulation of the Drosophila ortholog of mammalian TFEB, Mitf, a response that is unable to overcome the autophagy block. Together, our results suggest that rapamycin may have potential benefits in the treatment of GD, as well as PD linked to GBA1 mutations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1523/JNEUROSCI.4527-15.2016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5125225PMC
November 2016

Cyclooxygenase inhibition targets neurons to prevent early behavioural decline in Alzheimer's disease model mice.

Brain 2016 07 13;139(Pt 7):2063-81. Epub 2016 May 13.

1 Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, USA

Identifying preventive targets for Alzheimer's disease is a central challenge of modern medicine. Non-steroidal anti-inflammatory drugs, which inhibit the cyclooxygenase enzymes COX-1 and COX-2, reduce the risk of developing Alzheimer's disease in normal ageing populations. This preventive effect coincides with an extended preclinical phase that spans years to decades before onset of cognitive decline. In the brain, COX-2 is induced in neurons in response to excitatory synaptic activity and in glial cells in response to inflammation. To identify mechanisms underlying prevention of cognitive decline by anti-inflammatory drugs, we first identified an early object memory deficit in APPSwe-PS1ΔE9 mice that preceded previously identified spatial memory deficits in this model. We modelled prevention of this memory deficit with ibuprofen, and found that ibuprofen prevented memory impairment without producing any measurable changes in amyloid-β accumulation or glial inflammation. Instead, ibuprofen modulated hippocampal gene expression in pathways involved in neuronal plasticity and increased levels of norepinephrine and dopamine. The gene most highly downregulated by ibuprofen was neuronal tryptophan 2,3-dioxygenase (Tdo2), which encodes an enzyme that metabolizes tryptophan to kynurenine. TDO2 expression was increased by neuronal COX-2 activity, and overexpression of hippocampal TDO2 produced behavioural deficits. Moreover, pharmacological TDO2 inhibition prevented behavioural deficits in APPSwe-PS1ΔE9 mice. Taken together, these data demonstrate broad effects of cyclooxygenase inhibition on multiple neuronal pathways that counteract the neurotoxic effects of early accumulating amyloid-β oligomers.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/brain/aww117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4939702PMC
July 2016

Untangling the Web: Toxic and Protective Effects of Neuroinflammation and PGE2 Signaling in Alzheimer's Disease.

ACS Chem Neurosci 2016 Apr 4;7(4):454-63. Epub 2016 Apr 4.

Department of Neurology and Neurological Sciences, Stanford University School of Medicine , 1201 Welch Road, Stanford, California 94305, United States.

The neuroinflammatory response has received increasing attention as a key factor in the pathogenesis of Alzheimer's disease (AD). Microglia, the innate immune cells and resident phagocytes of the brain, respond to accumulating Aβ peptides by generating a nonresolving inflammatory response. While this response can clear Aβ peptides from the nervous system in some settings, its failure to do so in AD accelerates synaptic injury, neuronal loss, and cognitive decline. The complex molecular components of this response are beginning to be unraveled, with identification of both damaging and protective roles for individual components of the neuroinflammatory response. Even within one molecular pathway, contrasting effects are often present. As one example, recent studies of the inflammatory cyclooxygenase-prostaglandin pathway have revealed both beneficial and detrimental effects dependent on the disease context, cell type, and downstream signaling pathway. Nonsteroidal anti-inflammatory drugs (NSAIDs), which inhibit cyclooxygenases, are associated with reduced AD risk when taken by cognitively normal populations, but additional clinical and mouse model studies have added complexities and caveats to this finding. Downstream of cyclooxygenase activity, prostaglandin E2 signaling exerts both damaging pro-inflammatory and protective anti-inflammatory effects through actions of specific E-prostanoid G-protein coupled receptors on specific cell types. These complexities underscore the need for careful study of individual components of the neuroinflammatory response to better understand their contribution to AD pathogenesis and progression.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acschemneuro.6b00016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5239037PMC
April 2016

Microarray analysis of the in vivo response of microglia to Aβ peptides in mice with conditional deletion of the prostaglandin EP2 receptor.

Genom Data 2015 Sep;5:268-271

Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305.

Amyloid-β (Aβ) peptides accumulate in the brains of patients with Alzheimer's disease (AD), where they generate a persistent inflammatory response from microglia, the innate immune cells of the brain. The immune modulatory cyclooxygenase/prostaglandin E2 (COX/PGE) pathway has been implicated in preclinical AD development, both in human epidemiology studies and in transgenic rodent models of AD. PGE signals through four G-protein-coupled receptors, including the EP2 receptor that has been investigated for its role in mediating the inflammatory and phagocytic responses to Aβ. To identify transcriptional differences in microglia lacking the EP2 receptor, we examined mice with EP2 conditionally deleted in Cd11b-expressing immune cells. We injected Aβ peptides or saline vehicle into the brains of adult mice, isolated primary microglia, and analyzed RNA expression by microarray. The resulting datasets were analyzed in two studies, one describing the basal status of microglia with or without EP2 deletion, and the second study analyzing the microglial response to Aβ. Here we describe in detail the experimental design and data analyses. The raw data from these studies are deposited in GEO, accession GSE57181 (http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE57181).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.gdata.2015.06.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4522932PMC
September 2015

Inflammatory Cyclooxygenase Activity and PGE Signaling in Models of Alzheimer's Disease.

Curr Immunol Rev 2015 Aug;11(2):125-131

Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, USA.

The inflammatory response is a fundamental driving force in the pathogenesis of Alzheimer's disease (AD). In the setting of accumulating immunogenic Aß peptide assemblies, microglia, the innate immune cells of the brain, generate a non-resolving immune response and fail to adequately clear accumulating Aß peptides, accelerating neuronal and synaptic injury. Pathological, biomarker, and imaging studies point to a prominent role of the innate immune response in AD development, and the molecular components of this response are beginning to be unraveled. The inflammatory cyclooxygenase-PGE pathway is implicated in pre-clinical development of AD, both in epidemiology of normal aging populations and in transgenic mouse models of Familial AD. The cyclooxygenase-PGE pathway modulates the inflammatory response to accumulating Aß peptides through actions of specific E-prostanoid G-protein coupled receptors.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2174/1573395511666150707181414DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5384338PMC
August 2015

Prostaglandin signaling suppresses beneficial microglial function in Alzheimer's disease models.

J Clin Invest 2015 Jan 8;125(1):350-64. Epub 2014 Dec 8.

Microglia, the innate immune cells of the CNS, perform critical inflammatory and noninflammatory functions that maintain normal neural function. For example, microglia clear misfolded proteins, elaborate trophic factors, and regulate and terminate toxic inflammation. In Alzheimer's disease (AD), however, beneficial microglial functions become impaired, accelerating synaptic and neuronal loss. Better understanding of the molecular mechanisms that contribute to microglial dysfunction is an important objective for identifying potential strategies to delay progression to AD. The inflammatory cyclooxygenase/prostaglandin E2 (COX/PGE2) pathway has been implicated in preclinical AD development, both in human epidemiology studies and in transgenic rodent models of AD. Here, we evaluated murine models that recapitulate microglial responses to Aβ peptides and determined that microglia-specific deletion of the gene encoding the PGE2 receptor EP2 restores microglial chemotaxis and Aβ clearance, suppresses toxic inflammation, increases cytoprotective insulin-like growth factor 1 (IGF1) signaling, and prevents synaptic injury and memory deficits. Our findings indicate that EP2 signaling suppresses beneficial microglia functions that falter during AD development and suggest that inhibition of the COX/PGE2/EP2 immune pathway has potential as a strategy to restore healthy microglial function and prevent progression to AD.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1172/JCI77487DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4382270PMC
January 2015

Suppression of Alzheimer-associated inflammation by microglial prostaglandin-E2 EP4 receptor signaling.

J Neurosci 2014 Apr;34(17):5882-94

Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California 94305, Neurosciences Graduate Program, Stanford University, Stanford, California 94305, and Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232.

A persistent and nonresolving inflammatory response to accumulating Aβ peptide species is a cardinal feature in the development of Alzheimer's disease (AD). In response to accumulating Aβ peptide species, microglia, the innate immune cells of the brain, generate a toxic inflammatory response that accelerates synaptic and neuronal injury. Many proinflammatory signaling pathways are linked to progression of neurodegeneration. However, endogenous anti-inflammatory pathways capable of suppressing Aβ-induced inflammation represent a relatively unexplored area. Here we report that signaling through the prostaglandin-E2 (PGE2) EP4 receptor potently suppresses microglial inflammatory responses to Aβ42 peptides. In cultured microglial cells, EP4 stimulation attenuated levels of Aβ42-induced inflammatory factors and potentiated phagocytosis of Aβ42. Microarray analysis demonstrated that EP4 stimulation broadly opposed Aβ42-driven gene expression changes in microglia, with enrichment for targets of IRF1, IRF7, and NF-κB transcription factors. In vivo, conditional deletion of microglial EP4 in APPSwe-PS1ΔE9 (APP-PS1) mice conversely increased inflammatory gene expression, oxidative protein modification, and Aβ deposition in brain at early stages of pathology, but not at later stages, suggesting an early anti-inflammatory function of microglial EP4 signaling in the APP-PS1 model. Finally, EP4 receptor levels decreased significantly in human cortex with progression from normal to AD states, suggesting that early loss of this beneficial signaling system in preclinical AD development may contribute to subsequent progression of pathology.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1523/JNEUROSCI.0410-14.2014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3996215PMC
April 2014

Suppression of inflammation with conditional deletion of the prostaglandin E2 EP2 receptor in macrophages and brain microglia.

J Neurosci 2013 Oct;33(40):16016-32

Departments of Neurology and Neurological Sciences, Molecular and Cellular Physiology, Microbiology and Immunology, and Neurosurgery, Stanford University School of Medicine, Stanford, California 94305, Neurosciences Graduate Program, Stanford University, Stanford, California 94305, and Center for Health Sciences, SRI International, Menlo Park, California 94025.

Prostaglandin E2 (PGE2), a potent lipid signaling molecule, modulates inflammatory responses through activation of downstream G-protein coupled EP(1-4) receptors. Here, we investigated the cell-specific in vivo function of PGE2 signaling through its E-prostanoid 2 (EP2) receptor in murine innate immune responses systemically and in the CNS. In vivo, systemic administration of lipopolysaccharide (LPS) resulted in a broad induction of cytokines and chemokines in plasma that was significantly attenuated in EP2-deficient mice. Ex vivo stimulation of peritoneal macrophages with LPS elicited proinflammatory responses that were dependent on EP2 signaling and that overlapped with in vivo plasma findings, suggesting that myeloid-lineage EP2 signaling is a major effector of innate immune responses. Conditional deletion of the EP2 receptor in myeloid lineage cells in Cd11bCre;EP2(lox/lox) mice attenuated plasma inflammatory responses and transmission of systemic inflammation to the brain was inhibited, with decreased hippocampal inflammatory gene expression and cerebral cortical levels of IL-6. Conditional deletion of EP2 significantly blunted microglial and astrocytic inflammatory responses to the neurotoxin MPTP and reduced striatal dopamine turnover. Suppression of microglial EP2 signaling also increased numbers of dopaminergic (DA) neurons in the substantia nigra independent of MPTP treatment, suggesting that microglial EP2 may influence development or survival of DA neurons. Unbiased microarray analysis of microglia isolated from adult Cd11bCre;EP2(lox/lox) and control mice demonstrated a broad downregulation of inflammatory pathways with ablation of microglial EP2 receptor. Together, these data identify a cell-specific proinflammatory role for macrophage/microglial EP2 signaling in innate immune responses systemically and in brain.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1523/JNEUROSCI.2203-13.2013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3787507PMC
October 2013

Inflammatory prostaglandin E2 signaling in a mouse model of Alzheimer disease.

Ann Neurol 2012 Nov 22;72(5):788-98. Epub 2012 Aug 22.

Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, USA.

Objective: There is significant evidence for a central role of inflammation in the development of Alzheimer disease (AD). Epidemiological studies indicate that chronic use of nonsteroidal anti-inflammatory drugs (NSAIDs) reduces the risk of developing AD in healthy aging populations. As NSAIDs inhibit the enzymatic activity of the inflammatory cyclooxygenases COX-1 and COX-2, these findings suggest that downstream prostaglandin signaling pathways function in the preclinical development of AD. Here, we investigate the function of prostaglandin E(2) (PGE(2) ) signaling through its EP3 receptor in the neuroinflammatory response to Aβ peptide.

Methods: The function of PGE(2) signaling through its EP3 receptor was examined in vivo in a model of subacute neuroinflammation induced by administration of Aβ(42) peptides. Our findings were then confirmed in young adult APPSwe-PS1ΔE9 transgenic mice.

Results: Deletion of the PGE(2) EP3 receptor in a model of Aβ(42) peptide-induced neuroinflammation reduced proinflammatory gene expression, cytokine production, and oxidative stress. In the APPSwe-PS1ΔE9 model of familial AD, deletion of the EP3 receptor blocked induction of proinflammatory gene and protein expression and lipid peroxidation. In addition, levels of Aβ peptides were significantly decreased, as were β-secretase and β C-terminal fragment levels, suggesting that generation of Aβ peptides may be increased as a result of proinflammatory EP3 signaling. Finally, deletion of EP3 receptor significantly reversed the decline in presynaptic proteins seen in APPSwe-PS1ΔE9 mice.

Interpretation: Our findings identify the PGE(2) EP3 receptor as a novel proinflammatory, proamyloidogenic, and synaptotoxic signaling pathway, and suggest a role for COX-PGE(2) -EP3 signaling in the development of AD.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/ana.23677DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3509238PMC
November 2012

Signaling via the prostaglandin E₂ receptor EP4 exerts neuronal and vascular protection in a mouse model of cerebral ischemia.

J Clin Invest 2011 Nov 3;121(11):4362-71. Epub 2011 Oct 3.

Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, USA.

Stroke is the third leading cause of death in the United States. Fewer than 5% of patients benefit from the only intervention approved to treat stroke. Thus, there is an enormous need to identify new therapeutic targets. The role of inducible cyclooxygenase (COX-2) activity in stroke and other neurologic diseases is complex, as both activation and sustained inhibition can engender cerebral injury. Whether COX-2 induces cerebroprotective or injurious effects is probably dependent on which downstream prostaglandin receptors are activated. Here, we investigated the function of the PGE2 receptor EP4 in a mouse model of cerebral ischemia. Systemic administration of a selective EP4 agonist after ischemia reduced infarct volume and ameliorated long-term behavioral deficits. Expression of EP4 was robust in neurons and markedly induced in endothelial cells after ischemia-reperfusion, suggesting that neuronal and/or endothelial EP4 signaling imparts cerebroprotection. Conditional genetic inactivation of neuronal EP4 worsened stroke outcome, consistent with an endogenous protective role of neuronal EP4 signaling in vivo. However, endothelial deletion of EP4 also worsened stroke injury and decreased cerebral reperfusion. Systemic administration of an EP4 agonist increased levels of activated eNOS in cerebral microvessels, an effect that was abolished with conditional deletion of endothelial EP4. Thus, our data support the concept of targeting protective prostaglandin receptors therapeutically after stroke.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1172/JCI46279DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3204834PMC
November 2011

Amyloid beta protein-induced zinc sequestration leads to synaptic loss via dysregulation of the ProSAP2/Shank3 scaffold.

Mol Neurodegener 2011 Sep 22;6:65. Epub 2011 Sep 22.

Institute for Anatomy and Cell Biology, Ulm University, Albert Einstein Allee 11, Ulm, 89081, Germany.

Background: Memory deficits in Alzheimer's disease (AD) manifest together with the loss of synapses caused by the disruption of the postsynaptic density (PSD), a network of scaffold proteins located in dendritic spines. However, the underlying molecular mechanisms remain elusive. Since it was shown that ProSAP2/Shank3 scaffold assembly within the PSD is Zn2+-dependent and that the amyloid beta protein (Aβ) is able to bind Zn2+, we hypothesize that sequestration of Zn2+ ions by Aβ contributes to ProSAP/Shank platform malformation.

Results: To test this hypothesis, we designed multiple in vitro and in vivo assays demonstrating ProSAP/Shank dysregulation in rat hippocampal cultures following Aβ oligomer accumulation. These changes were independent from alterations on ProSAP/Shank transcriptional level. However, application of soluble Aβ prevented association of Zn2+ ions with ProSAP2/Shank3 in a cell-based assay and decreased the concentration of Zn2+ clusters within dendrites. Zn2+ supplementation or saturation of Aβ with Zn2+ ions prior to cell treatment was able to counter the effects induced by Aβ on synapse density and ProSAP2/Shank3 levels at the PSD. Interestingly, intracellular Zn2+ levels in APP-PS1 mice and human AD hippocampus are reduced along with a reduction in synapse density and synaptic ProSAP2/Shank3 and Shank1 protein levels.

Conclusions: We conclude that sequestration of Zn2+ ions by Aβ significantly contributes to changes in ProSAP2/Shank3 platforms. These changes in turn lead to less consolidated (mature) synapses reflected by a decrease in Shank1 protein levels at the PSD and decreased synapse density in hippocampal neurons.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/1750-1326-6-65DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3189132PMC
September 2011

The prostaglandin E2 E-prostanoid 4 receptor exerts anti-inflammatory effects in brain innate immunity.

J Immunol 2010 Jun 7;184(12):7207-18. Epub 2010 May 7.

Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, USA.

Peripheral inflammation leads to immune responses in brain characterized by microglial activation, elaboration of proinflammatory cytokines and reactive oxygen species, and secondary neuronal injury. The inducible cyclooxygenase (COX), COX-2, mediates a significant component of this response in brain via downstream proinflammatory PG signaling. In this study, we investigated the function of the PGE2 E-prostanoid (EP) 4 receptor in the CNS innate immune response to the bacterial endotoxin LPS. We report that PGE2 EP4 signaling mediates an anti-inflammatory effect in brain by blocking LPS-induced proinflammatory gene expression in mice. This was associated in cultured murine microglial cells with decreased Akt and I-kappaB kinase phosphorylation and decreased nuclear translocation of p65 and p50 NF-kappaB subunits. In vivo, conditional deletion of EP4 in macrophages and microglia increased lipid peroxidation and proinflammatory gene expression in brain and in isolated adult microglia following peripheral LPS administration. Conversely, EP4 selective agonist decreased LPS-induced proinflammatory gene expression in hippocampus and in isolated adult microglia. In plasma, EP4 agonist significantly reduced levels of proinflammatory cytokines and chemokines, indicating that peripheral EP4 activation protects the brain from systemic inflammation. The innate immune response is an important component of disease progression in a number of neurodegenerative disorders, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. In addition, recent studies demonstrated adverse vascular effects with chronic administration of COX-2 inhibitors, indicating that specific PG signaling pathways may be protective in vascular function. This study supports an analogous and beneficial effect of PGE2 EP4 receptor signaling in suppressing brain inflammation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4049/jimmunol.0903487DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3103215PMC
June 2010

Insertional inactivation of the L13a ribosomal protein gene of Drosophila melanogaster identifies a new Minute locus.

Gene 2006 Mar 2;368:46-52. Epub 2005 Dec 2.

Department of Biology, Emory University, Rollins Research Building, 1510 Clifton Road, Atlanta, GA. 30322, United States.

We have utilized a transposable P element construct to scan the genome for modifiers of Drosophila Notch pathway phenotypes. From a collection of 2000 inserts we obtained two enhancers and one suppressor. Sequence analysis of the insertion regions demonstrated that two modifiers affect known components of the Notch pathway, whereas the third is an insert in the gene encoding ribosomal protein L13a at cytogenetic region 83B6-7. The insert in the RpL13A coding region creates a classic Minute mutation which enhances Notch pathway wing phenotypes. This report adds RpL13A to the list of Drosophila ribosomal protein genes that cause Minute phenotypes when mutated.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.gene.2005.10.005DOI Listing
March 2006

The role of histone acetylation in SMN gene expression.

Hum Mol Genet 2005 May 16;14(9):1171-82. Epub 2005 Mar 16.

Neurogenetics Branch, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA.

Increasing survival motor neuron 2 (SMN2) gene expression may be an effective strategy for the treatment of spinal muscular atrophy (SMA). Histone deacetylase (HDAC) inhibitors have been shown to increase SMN transcript and protein levels, but the specific role of histone acetylation in regulating SMN gene expression has not been explored. Using chromatin immunopreciptation, we investigated the levels of acetylated H3 and H4 histones and HDACs associated with different regions of the human and mouse SMN genes in both cultured cells and tissues. We show that the SMN gene has a reproducible pattern of histone acetylation that is largely conserved among different tissues and species. A limited region of the promoter surrounding the transcriptional start site has relatively high levels of histone acetylation, whereas regions further upstream or downstream have lower levels. After HDAC inhibitor treatment, acetylated histone levels increased, particularly at upstream regions, correlating with a 2-fold increase in promoter activity. During development in mouse tissues, histone acetylation levels decreased and associated HDAC2 levels increased at the region closest to the transcriptional start site, correlating with a 40-60% decrease in SMN transcript and protein levels. These data indicate that histone acetylation modulates SMN gene expression and that pharmacological manipulation of this epigenetic determinant is feasible. HDAC2, in particular, may be a future therapeutic target for SMA.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/hmg/ddi130DOI Listing
May 2005

An EP overexpression screen for genetic modifiers of Notch pathway function in Drosophila melanogaster.

Genet Res 2004 Apr;83(2):71-82

Department of Biology, Emory University, Atlanta, GA 30322, USA.

The Notch pathway comprises a signal transduction cascade required for the proper formation of multiple tissues during metazoan development. Originally described in Drosophila for its role in nervous system formation, the pathway has attracted much wider interest owing to its fundamental roles in a range of developmental and disease-related processes. Despite extensive analysis, Notch signaling is not completely understood and it appears that additional components of the pathway remain to be identified and characterized. Here, we describe a novel genetic strategy to screen for additional Notch pathway genes. The strategy combines partial loss of function for pathway activity with Enhancer-promoter (EP)-induced overexpression of random loci across the dorsoventral wing margin. Mastermind (Mam) is a nuclear component of the Notch signaling cascade. Using a GAL4-UAS-driven dominant-negative form of Mam, we created a genotype that exhibits a completely penetrant dominant wing-nicking phenotype. This phenotype was assayed for enhancement or suppression after outcrossing to several thousand EP lines. The screen identified known components or modifiers of Notch pathway function, as well as several potential new components. Our results suggest that a genetic screen that combines partial loss of function with random gene overexpression might be a useful strategy in the analysis of developmental pathways.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1017/s0016672304006731DOI Listing
April 2004