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Microglia and lysosome

Kai-Chih Hung, Hui-Ju Huang, Yi-Ting Wang, Anya Maan-Yuh Lin
ETHNOPHARMACOLOGICAL RELEVANCE: Neuroinflammation, oxidative stress, and protein aggregation form a vicious cycle in the pathophysiology of Parkinson's disease (PD); activated microglia is the main location of neuroinflammation. A Chinese medicine book, "Shanghan Lun", known as the "Treatises on Cold damage Diseases" has suggested that Scutellaria baicalensis Georgi is effective in treating CNS diseases. The anti-inflammatory mechanisms of baicalein, a phenolic flavonoid in the dried root of Scutellaria baicalensis Georgi, remain to be explored...
October 11, 2016: Journal of Ethnopharmacology
Jie Yin, Xiaocui Liu, Qing He, Lujun Zhou, Zengqiang Yuan, Siqi Zhao
Triggering receptor expressed on myeloid cells 2 (Trem2), an immune-modulatory receptor, is preferentially expressed in microglia of central nervous system. Trem2 might be involved in the development of Alzheimer's disease through regulating the inflammatory responses and phagocytosis of microglia. However, the intracellular trafficking of Trem2 remains unclear. In this study, we showed that Trem2 in the plasma membrane underwent endocytosis and recycling. Trem2 is internalized in a clathrin-dependent manner and then recycled back to the plasma membrane through Vps35, the key component of cargo recognition core of retromer complex, but not Rab11...
September 26, 2016: Traffic
Peter Thériault, Serge Rivest
Growing evidence highlights the crucial physiological functions of microglia that rely on their phagocytic activities, which can be compromised with age. A new study reports the impaired clearance of myelin debris by microglia in the brain, leading to insoluble lysosomal inclusions and contributing to the immune dysfunction and senescence of these cells.
August 22, 2016: Current Biology: CB
Lisa K Gouwens, Nyasha J Makoni, Victoria A Rogers, Michael R Nichols
One pathological hallmark of Alzheimer's disease (AD) is the accumulation of amyloid-β peptide (Aβ) in the affected brain. While there are numerous deleterious effects of Aβ accumulation, there is general agreement that a sustained inflammatory response to aggregated Aβ contributes to progressive neurodegeneration in AD and microglial cells play a significant role in this process. Our laboratory and others have shown that small soluble aggregates of Aβ activate a microglia-mediated inflammatory response...
October 1, 2016: Brain Research
Hyun Jung Park, Se Hee Oh, Ha Na Kim, Yu Ju Jung, Phil Hyu Lee
Microglia in the brain show distinctive phenotypes that serve different functions. In particular, M2-polarized microglia are anti-inflammatory and phagocytic cells that serve a restorative function. In this study, we investigated whether mesenchymal stem cells (MSCs) enhance the phagocytic clearance of α-synuclein via M2 microglia polarization, and thereby exert neuroprotective effects in α-synuclein-enriched experimental models and patients with multiple system atrophy (MSA). Treatment of BV2 cells with α-synuclein induced an inflammatory phenotype, whereas co-culture of α-synuclein-treated BV2 cells with MSCs induced an anti-inflammatory M2 phenotype, with decreased α-synuclein levels and increased lysosomal activity, leading to greater viability of neuronal cells co-cultured with BV2 cells...
November 2016: Acta Neuropathologica
Kyoko Suzuki, Akira Yamaguchi, Shoji Yamanaka, Seiichi Kanzaki, Masato Kawashima, Takashi Togo, Omi Katsuse, Noriko Koumitsu, Naoya Aoki, Eizo Iseki, Kenji Kosaka, Kayoko Yamaguchi, Makoto Hashimoto, Ichiro Aoki, Yoshio Hirayasu
The accumulation of α-synuclein (ASyn) has been observed in several lysosomal storage diseases (LSDs) but it remains unclear if ASyn accumulation contributes to LSD pathology. ASyn also accumulates in the neurons of Sandhoff disease (SD) patients and SD model mice (Hexb-/- ASyn+/+ mice). SD is a lysosomal storage disorder caused by the absence of a functional β-subunit on the β-hexosaminidase A and B enzymes, which leads to the accumulation of ganglioside in the central nervous system. Here, we explored the role of accumulated ASyn in the progression of Hexb-/- mice by creating a Hexb-/- ASyn-/- double-knockout mice...
July 21, 2016: Experimental Neurology
Willem Kamphuis, Lieneke Kooijman, Sjoerd Schetters, Marie Orre, Elly M Hol
Amyloid plaques in Alzheimer's disease (AD) mice are surrounded by activated microglia. The functional role of microglia activation in AD is not well understood; both detrimental and beneficial effects on AD progression have been reported. Here we show that the population of activated microglia in the cortex of the APPswe/PS1dE9 mouse AD model is divided into a CD11c-positive and a CD11c-negative subpopulation. Cd11c transcript levels and number of CD11c-positive microglia increase sharply when plaques start to occur and both parameters continue to rise in parallel with the age-related increasing plaque load...
October 2016: Biochimica et Biophysica Acta
Santiago Solé-Domènech, Dana L Cruz, Estibaliz Capetillo-Zarate, Frederick R Maxfield
Microglia, the main phagocytes of the central nervous system (CNS), are involved in the surveillance and maintenance of nervous tissue. During normal tissue homeostasis, microglia migrates within the CNS, phagocytose dead cells and tissue debris, and modulate synapse pruning and spine formation via controlled phagocytosis. In the event of an invasion by a foreign body, microglia are able to phagocytose the invading pathogen and process it proteolytically for antigen presentation. Internalized substrates are incorporated and sorted within the endocytic pathway and thereafter transported via complex vesicular routes...
July 12, 2016: Ageing Research Reviews
Mastura Monif, Christopher A Reid, Kim L Powell, Katherine J Drummond, Terrence J O'Brien, David A Williams
BACKGROUND: Enhanced expression of the purinergic P2X7 receptor (P2X7R) occurs in several neuroinflammatory conditions where increased microglial activation is a co-existing feature. P2X7 receptors can function either as a cation channel or, upon continued stimulation, a large pore. P2X7R-over-expression alone is sufficient to drive microglial activation and proliferation in a process that is P2X7R pore dependent, although the biological signaling pathway through which this occurs remains unclear...
2016: Journal of Neuroinflammation
Shima Safaiyan, Nirmal Kannaiyan, Nicolas Snaidero, Simone Brioschi, Knut Biber, Simon Yona, Aimee L Edinger, Steffen Jung, Moritz J Rossner, Mikael Simons
Myelin is synthesized as a multilamellar membrane, but the mechanisms of membrane turnover are unknown. We found that myelin pieces were gradually released from aging myelin sheaths and were subsequently cleared by microglia. Myelin fragmentation increased with age and led to the formation of insoluble, lipofuscin-like lysosomal inclusions in microglia. Thus, age-related myelin fragmentation is substantial, leading to lysosomal storage and contributing to microglial senescence and immune dysfunction in aging...
August 2016: Nature Neuroscience
Marquis T Walker, Craig Montell
Mucolipidosis IV (MLIV) is a severe lysosomal storage disorder, which results from loss of the TRPML1 channel. MLIV causes multiple impairments in young children, including severe motor deficits. Currently, there is no effective treatment. Using a Drosophila MLIV model, we showed previously that introduction of trpml(+) in phagocytic glia rescued the locomotor deficit by removing early dying neurons, thereby preventing amplification of neuronal death from cytotoxicity. Because microglia, which are phagocytic cells in the mammalian brain, are bone marrow derived, and cross the blood brain barrier, we used a mouse MLIV model to test the efficacy of bone marrow transplantation (BMT)...
June 7, 2016: Human Molecular Genetics
I-Lun Hsiao, Chia-Cheng Chang, Chung-Yi Wu, Yi-Kong Hsieh, Chun-Yu Chuang, Chu-Fang Wang, Yuh-Jeen Huang
Although, titanium dioxide nanoparticles (TiO2NPs) are nanomaterials commonly used in consumer products, little is known about their hazardous effects, especially on central nervous systems. To examine this issue, ALT astrocyte-like, BV-2 microglia and differentiated N2a neuroblastoma cells were exposed to 6 nm of 100% anatase TiO2NPs. A lipopolysaccharide (LPS) was pre-treated to activate glial cells before NP treatment for mimicking NP exposure under brain injury. We found that ALT and BV-2 cells took up more NPs than N2a cells and caused lower cell viability...
July 25, 2016: Chemico-biological Interactions
Yanbo Ma, Takashi Matsuwaki, Keitaro Yamanouchi, Masugi Nishihara
Immune stress is well known to suppress adult neurogenesis in the hippocampus. We have demonstrated that progranulin (PGRN) has a mitogenic effect on neurogenesis under several experimental conditions. We have also shown that PGRN suppresses excessive neuroinflammatory responses after traumatic brain injury. However, the role of PGRN in modulating neurogenesis under acute immune stress is yet to be elucidated. In the present study, we evaluated the involvement of PGRN in neurogenesis and inflammatory responses in the hippocampus using a lipopolysaccharide (LPS)-induced immune stress model...
May 23, 2016: Molecular Neurobiology
Jintao Bao, Liangjun Zheng, Qi Zhang, Xinya Li, Xuefei Zhang, Zeyang Li, Xue Bai, Zhong Zhang, Wei Huo, Xuyang Zhao, Shujiang Shang, Qingsong Wang, Chen Zhang, Jianguo Ji
Microglia play a pivotal role in clearance of Aβ by degrading them in lysosomes, countering amyloid plaque pathogenesis in Alzheimer's disease (AD). Recent evidence suggests that lysosomal dysfunction leads to insufficient elimination of toxic protein aggregates. We tested whether enhancing lysosomal function with transcription factor EB (TFEB), an essential regulator modulating lysosomal pathways, would promote Aβ clearance in microglia. Here we show that microglial expression of TFEB facilitates fibrillar Aβ (fAβ) degradation and reduces deposited amyloid plaques, which are further enhanced by deacetylation of TFEB...
June 2016: Protein & Cell
Einat B Vitner, Tamar Farfel-Becker, Natalia Santos Ferreira, Dena Leshkowitz, Piyush Sharma, Karl S Lang, Anthony H Futerman
BACKGROUND: Neuroinflammation is a key phenomenon in the pathogenesis of many neurodegenerative diseases. Understanding the mechanisms by which brain inflammation is engaged and delineating the key players in the immune response and their contribution to brain pathology is of great importance for the identification of novel therapeutic targets for these devastating diseases. Gaucher disease, the most common lysosomal storage disease, is caused by mutations in the GBA1 gene and is a significant risk factor for Parkinson's disease; in some forms of Gaucher disease, neuroinflammation is observed...
2016: Journal of Neuroinflammation
Nunzia Pastore, Owen A Brady, Heba I Diab, José A Martina, Lu Sun, Tuong Huynh, Jeong-A Lim, Hossein Zare, Nina Raben, Andrea Ballabio, Rosa Puertollano
The activation of transcription factors is critical to ensure an effective defense against pathogens. In this study we identify a critical and complementary role of the transcription factors TFEB and TFE3 in innate immune response. By using a combination of chromatin immunoprecipitation, CRISPR-Cas9-mediated genome-editing technology, and in vivo models, we determined that TFEB and TFE3 collaborate with each other in activated macrophages and microglia to promote efficient autophagy induction, increased lysosomal biogenesis, and transcriptional upregulation of numerous proinflammatory cytokines...
August 2, 2016: Autophagy
Tsubasa Takizawa, Mamoru Shibata, Yohei Kayama, Toshihiko Shimizu, Haruki Toriumi, Taeko Ebine, Miyuki Unekawa, Anri Koh, Akihiko Yoshimura, Norihiro Suzuki
Single episodes of cortical spreading depression (CSD) are believed to cause typical migraine aura, whereas clusters of spreading depolarizations have been observed in cerebral ischemia and subarachnoid hemorrhage. We recently demonstrated that the release of high-mobility group box 1 (HMGB1) from cortical neurons after CSD in a rodent model is dependent on the number of CSD episodes, such that only multiple CSD episodes can induce significant HMGB1 release. Here, we report that only multiple CSD inductions caused microglial hypertrophy (activation) accompanied by a greater impact on the transcription activity of the HMGB1 receptor genes, TLR2 and TLR4, while the total number of cortical microglia was not affected...
May 3, 2016: Journal of Cerebral Blood Flow and Metabolism
Bing-Huan Huang, Zhi-Rong Geng, Xiao-Yan Ma, Cui Zhang, Zhi-Yang Zhang, Zhi-Lin Wang
Lysosomes in astrocytes and microglia can release ATP as the signaling molecule for the cells through ca(2+)-dependent exocytosis in response to various stimuli. At present, fluorescent probes that can detect ATP in lysosomes have not been reported. In this work, we have developed a new water-soluble cationic polythiophene derivative that can be specifically localized in lysosomes and can be utilized as a fluorescent probe to sense ATP in cells. PEMTEI exhibits high selectivity and sensitivity to ATP at physiological pH values and the detection limit of ATP is as low as 10(-11)M...
September 15, 2016: Biosensors & Bioelectronics
Stephen L Hayward, Christina L Wilson, Srivatsan Kidambi
Glioblastoma Multiforme (GBM) is a highly prevalent and deadly brain malignancy characterized by poor prognosis and restricted disease management potential. Despite the success of nanocarrier systems to improve drug/gene therapy for cancer, active targeting specificity remains a major hurdle for GBM. Additionally, since the brain is a multi-cell type organ, there is a critical need to develop an approach to distinguish between GBM cells and healthy brain cells for safe and successful treatment. In this report, we have incorporated hyaluronic acid (HA) as an active targeting ligand for GBM...
June 7, 2016: Oncotarget
Hansen Lui, Jiasheng Zhang, Stefanie R Makinson, Michelle K Cahill, Kevin W Kelley, Hsin-Yi Huang, Yulei Shang, Michael C Oldham, Lauren Herl Martens, Fuying Gao, Giovanni Coppola, Steven A Sloan, Christine L Hsieh, Charles C Kim, Eileen H Bigio, Sandra Weintraub, Marek-Marsel Mesulam, Rosa Rademakers, Ian R Mackenzie, William W Seeley, Anna Karydas, Bruce L Miller, Barbara Borroni, Roberta Ghidoni, Robert V Farese, Jeanne T Paz, Ben A Barres, Eric J Huang
Microglia maintain homeostasis in the brain, but whether aberrant microglial activation can cause neurodegeneration remains controversial. Here, we use transcriptome profiling to demonstrate that deficiency in frontotemporal dementia (FTD) gene progranulin (Grn) leads to an age-dependent, progressive upregulation of lysosomal and innate immunity genes, increased complement production, and enhanced synaptic pruning in microglia. During aging, Grn(-/-) mice show profound microglia infiltration and preferential elimination of inhibitory synapses in the ventral thalamus, which lead to hyperexcitability in the thalamocortical circuits and obsessive-compulsive disorder (OCD)-like grooming behaviors...
May 5, 2016: Cell
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