(glial cell membrane) articles in PubMed
- Adenosine A2A receptor and ecto-5'-nucleotidase/CD73 are upregulated in hippocampal astrocytes of human patients with mesial temporal lobe epilepsy (MTLE). [Journal Article]
- Purinergic Signal 2016 Sep 20PS
- Refractoriness to existing medications of up to 80 % of the patients with mesial temporal lobe epilepsy (MTLE) prompts for finding new antiepileptic drug targets. The adenosine A2A receptor emerges a...
Refractoriness to existing medications of up to 80 % of the patients with mesial temporal lobe epilepsy (MTLE) prompts for finding new antiepileptic drug targets. The adenosine A2A receptor emerges as an interesting pharmacological target since its excitatory nature partially counteracts the dominant antiepileptic role of endogenous adenosine acting via inhibitory A1 receptors. Gain of function of the excitatory A2A receptor has been implicated in a significant number of brain pathologies commonly characterized by neuronal excitotoxicity. Here, we investigated changes in the expression and cellular localization of the A2A receptor and of the adenosine-generating enzyme, ecto-5'-nucleotidase/CD73, in the hippocampus of control individuals and MTLE human patients. Western blot analysis indicates that the A2A receptor is more abundant in the hippocampus of MTLE patients compared to control individuals. Immunoreactivity against the A2A receptor predominates in astrocytes staining positively for the glial fibrillary acidic protein (GFAP). No co-localization was observed between the A2A receptor and neuronal cell markers, like synaptotagmin 1/2 (nerve terminals) and neurofilament 200 (axon fibers). Hippocampal astrogliosis observed in MTLE patients was accompanied by a proportionate increase in A2A receptor and ecto-5'-nucleotidase/CD73 immunoreactivities. Given our data, we hypothesize that selective blockade of excessive activation of astrocytic A2A receptors and/or inhibition of surplus adenosine formation by membrane-bound ecto-5'-nucleotidase/CD73 may reduce neuronal excitability, thus providing a novel therapeutic target for drug-refractory seizures in MTLE patients.
- Autoantibody-Associated Central Nervous System Neurologic Disorders. [Journal Article]
- Semin Neurol 2016; 36(4):382-96SN
- Autoimmune neurology is a rapidly evolving new subspecialty driven by the discovery of novel neural- (neuronal- or glial-) specific autoantibodies and their target antigens. The neurologic manifestat...
Autoimmune neurology is a rapidly evolving new subspecialty driven by the discovery of novel neural- (neuronal- or glial-) specific autoantibodies and their target antigens. The neurologic manifestations affecting the central nervous system include encephalitis, dementia, epilepsy, and movement and sleep disorders. Laboratory testing is now available for most of these neural-specific autoantibodies, which serve as diagnostic markers, in some instances directing the physician toward specific cancer types (e.g., N-methyl-D-aspartic acid receptor antibodies for teratoma, collapsin response mediator protein 5 for small-cell lung cancer) and assisting in therapeutic decision making. Antibodies targeting intracellular proteins serve as markers of cytotoxic effector T-cell-mediated injury, which is generally poorly responsive to immunotherapy. By contrast, antibodies targeting extracellular plasma membrane proteins may act as pathogenic effectors and often infer good responses to immunotherapy. Diagnosing these conditions and implementing treatment as early into the clinical course as possible ensures the best possible clinical outcomes. An adequate immunotherapy trial to assess maximum reversibility of symptoms, as assessed through objective functional measures, is crucial and can help to determine whether maintenance therapy is needed.
- Fluid levity of the cell: Role of membrane lipid architecture in genetic sphingolipidoses. [Journal Article]
- J Neurosci Res 2016; 94(11):1019-24JN
- Sphingolipidoses arise from inherited loss of function of key enzymes regulating the sphingolipid (SL) metabolism and the accumulation of large quantities of these lipids in affected cells. Most freq...
Sphingolipidoses arise from inherited loss of function of key enzymes regulating the sphingolipid (SL) metabolism and the accumulation of large quantities of these lipids in affected cells. Most frequently, toxicity is manifested in the nervous system, where survival and function of neurons and glial cells are most affected. Although detailed information is available on neuroglial alterations during terminal stages of the disease, the initial pathogenic mechanisms triggering neuropathology are largely unclear. Because they are key components of biological membranes, changes in the local concentration of SLs are likely to impact the organization of membrane domains and functions. This Commentary proposes that SL toxicity involves initial defects in the integrity of lipid domains, membrane fluidity, and membrane bending, leading to membrane deformation and deregulation of cell signaling and function. Understanding how SLs alter membrane architecture may provide breakthroughs for more efficient treatment of sphingolipidoses. © 2016 Wiley Periodicals, Inc.
- Astroglial Vesicular Trafficking in Neurodegenerative Diseases. [Journal Article]
- Neurochem Res 2016 Sep 14NR
- The neocortex represents one of the largest estates of the human brain. This structure comprises ~30-40 billions of neurones and even more of non-neuronal cells. Astrocytes, highly heterogeneous homo...
The neocortex represents one of the largest estates of the human brain. This structure comprises ~30-40 billions of neurones and even more of non-neuronal cells. Astrocytes, highly heterogeneous homoeostatic glial cells, are fundamental for housekeeping of the brain and contribute to information processing in neuronal networks. Gray matter astrocytes tightly enwrap synapses, contact blood vessels and, naturally, are also in contact with the extracellular space, where convection of fluid takes place. Thus astrocytes receive signals from several distinct extracellular domains and can get excited by numerous mechanisms, which regulate cytosolic concentration of second messengers, such as Ca(2+) and cAMP. Excited astrocytes often secrete diverse substances (generally referred to as gliosignalling molecules) that include classical neurotransmitters such as glutamate and ATP or neuromodulators such as D-serine or neuropeptides. Astrocytic secretion occurs through several mechanisms: by diffusion through membrane channels, by translocation via plasmalemmal transporters or by vesicular exocytosis. Vesicular release of gliosignalling molecules appears fundamentally similar to that operating in neurones, since it depends on the SNARE proteins-dependent merger of the vesicle membrane with the plasmalemma. However, the coupling between the stimulus and astroglial vesicular secretion is at least one order of magnitude slower than that in neurones. Here we review mechanisms of astrocytic excitability and the molecular, anatomical and physiological properties of vesicular apparatus mediating the release of gliosignalling molecules in health and in the neurodegenerative pathology.
- Is Low Non-Lethal Concentration of Methylmercury Really Safe? A Report on Genotoxicity with Delayed Cell Proliferation. [Journal Article]
- PLoS One 2016; 11(9):e0162822Plos
- Human exposure to relatively low levels of methylmercury is worrying, especially in terms of its genotoxicity. It is currently unknown as to whether exposure to low levels of mercury (below establish...
Human exposure to relatively low levels of methylmercury is worrying, especially in terms of its genotoxicity. It is currently unknown as to whether exposure to low levels of mercury (below established limits) is safe. Genotoxicity was already shown in lymphocytes, but studies with cells of the CNS (as the main target organ) are scarce. Moreover, disturbances in the cell cycle and cellular proliferation have previously been observed in neuronal cells, but no data are presently available for glial cells. Interestingly, cells of glial origin accumulate higher concentrations of methylmercury than those of neuronal origin. Thus, the aim of this work was to analyze the possible genotoxicity and alterations in the cell cycle and cell proliferation of a glioma cell line (C6) exposed to a low, non-lethal and non-apoptotic methylmercury concentration. Biochemical (mitochondrial activity) and morphological (integrity of the membrane) assessments confirmed the absence of cell death after exposure to 3 μM methylmercury for 24 hours. Even without promoting cell death, this treatment significantly increased genotoxicity markers (DNA fragmentation, micronuclei, nucleoplasmic bridges and nuclear buds). Changes in the cell cycle profile (increased mitotic index and cell populations in the S and G2/M phases) were observed, suggesting arrest of the cycle. This delay in the cycle was followed, 24 hours after methylmercury withdrawal, by a decrease number of viable cells, reduced cellular confluence and increased doubling time of the culture. Our work demonstrates that exposure to a low sublethal concentration of MeHg considered relatively safe according to current limits promotes genotoxicity and disturbances in the proliferation of cells of glial origin with sustained consequences after methylmercury withdrawal. This fact becomes especially important, since this cellular type accumulates more methylmercury than neurons and displays a vital role protecting the CNS, especially in chronic intoxication with this heavy metal.
- Human astrocytes secrete IL-6 to promote glioma migration and invasion through upregulation of cytomembrane MMP14. [Journal Article]
- Oncotarget 2016 Aug 23O
- The brain microenvironment has emerged as an important component in malignant progression of human glioma. However, astrocytes, the most abundant glial cells in the glioma microenvironment, have as y...
The brain microenvironment has emerged as an important component in malignant progression of human glioma. However, astrocytes, the most abundant glial cells in the glioma microenvironment, have as yet a poorly defined role in the development of this disease, particularly with regard to invasion. Here, we co-cultured human astrocytes with human glioma cell lines, U251 and A172, in an in vitro transwell system in order to ascertain their influence on migration and invasion of gliomas. mRNA and protein expression assays were subsequently used to identify candidate proteins mediating this activity. Astrocytes significantly increased migration and invasion of both U251 and A172 cells in migration and invasion (plus matrigel) assays. Membrane type 1 matrix metalloproteinase (MMP14) originating from glioma cells was identified in qRT-PCR as the most highly up-regulated member of the MMP family of genes (~ 3 fold, p < 0.05) in this system. A cytokine array and ELISA were used to identify interleukin-6 (IL-6) as a highly increased factor in media collected from astrocytes, especially under co-culture conditions. IL-6 was also the key cytokine inducing cytomembrane MMP14 expression, the active form of MMP14, in glioma cells. Knockdown of MMP14 with siRNA led to decreased migration and invasion. Taken together, our results indicated that cytomembrane MMP14 was induced by IL-6 secreted from astrocytes, thereby enhancing the migration and invasion of glioma cells through activation of MMP2. Therefore, this IL-6 and MMP14 axis between astrocytes and glioma cells may become a potential target for treatment of glioma patients.
- HIV-1 Tat promotes lysosomal exocytosis in astrocytes and contributes to astrocyte-mediated Tat neurotoxicity. [Journal Article]
- J Biol Chem 2016 Sep 8JB
- Tat interaction with astrocytes has been shown to be important for Tat neurotoxicity and HIV/neuroAIDS. We have recently shown that Tat expression leads to increased glial fibrillary acidic protein (...
Tat interaction with astrocytes has been shown to be important for Tat neurotoxicity and HIV/neuroAIDS. We have recently shown that Tat expression leads to increased glial fibrillary acidic protein (GFAP) expression and aggregation and activation of unfolded protein response/endoplasmic reticulum stress in astrocytes and causes neurotoxicity. However, the exact molecular mechanisms of astrocyte-mediated Tat neurotoxicity is not defined. In this study, we showed that neurotoxic factors other than Tat protein itself were present in the supernatant of Tat-expressing astrocytes. Two-dimensional gel electrophoresis and mass spectrometry revealed significantly elevated lysosomal hydrolytic enzymes and plasma membrane-associated proteins in the supernatant of Tat-expressing astrocytes. We confirmed that Tat expression and infection of pseudotyped HIV.GFP led to increased lysosomal exocytosis from mouse astrocytes and human astrocytes. We found that Tat-induced lysosomal exocytosis was tightly coupled to astrocyte-mediated Tat neurotoxicity. In addition, we demonstrated that Tat-induced lysosomal exocytosis was astrocyte-specific and required GFAP expression and was mediated by ER stress. Taken together, these results show for the first time that Tat promotes lysosomal exocytosis in astrocytes and causes neurotoxicity through GFAP activation and ER stress induction in astrocytes and suggest a common cascade through which aberrant astrocytosis/GFAP up-regulation potentiates neurotoxicity and contributes to neurodegenerative diseases.
- The Emerging Roles of the Calcineurin-Nuclear Factor of Activated T-Lymphocytes Pathway in Nervous System Functions and Diseases. [Review]
- J Aging Res 2016; 2016:5081021JA
- The ongoing epidemics of metabolic diseases and increase in the older population have increased the incidences of neurodegenerative diseases. Evidence from murine and cell line models has implicated ...
The ongoing epidemics of metabolic diseases and increase in the older population have increased the incidences of neurodegenerative diseases. Evidence from murine and cell line models has implicated calcineurin-nuclear factor of activated T-lymphocytes (NFAT) signaling pathway, a Ca(2+)/calmodulin-dependent major proinflammatory pathway, in the pathogenesis of these diseases. Neurotoxins such as amyloid-β, tau protein, and α-synuclein trigger abnormal calcineurin/NFAT signaling activities. Additionally increased activities of endogenous regulators of calcineurin like plasma membrane Ca(2+)-ATPase (PMCA) and regulator of calcineurin 1 (RCAN1) also cause neuronal and glial loss and related functional alterations, in neurodegenerative diseases, psychotic disorders, epilepsy, and traumatic brain and spinal cord injuries. Treatment with calcineurin/NFAT inhibitors induces some degree of neuroprotection and decreased reactive gliosis in the central and peripheral nervous system. In this paper, we summarize and discuss the current understanding of the roles of calcineurin/NFAT signaling in physiology and pathologies of the adult and developing nervous system, with an emphasis on recent reports and cutting-edge findings. Calcineurin/NFAT signaling is known for its critical roles in the developing and adult nervous system. Its role in physiological and pathological processes is still controversial. However, available data suggest that its beneficial and detrimental effects are context-dependent. In view of recent reports calcineurin/NFAT signaling is likely to serve as a potential therapeutic target for neurodegenerative diseases and conditions. This review further highlights the need to characterize better all factors determining the outcome of calcineurin/NFAT signaling in diseases and the downstream targets mediating the beneficial and detrimental effects.
- Altered gene expression of glycosyltransferases and sialyltransferases and total amount of glycosphingolipids following herpes simplex virus infection. [Journal Article]
- Carbohydr Res 2016 Aug 18; 434:37-43CR
- There is a case report of a patient with overlapping Guillain-Barré syndrome and Bickerstaff brainstem encephalitis after infection with herpes simplex virus type 1 (HSV-1), who carried high titers o...
There is a case report of a patient with overlapping Guillain-Barré syndrome and Bickerstaff brainstem encephalitis after infection with herpes simplex virus type 1 (HSV-1), who carried high titers of serum anti-GQ1b IgG antibodies. Several studies have linked viral infection to the modulation of ganglioside expression such as human T-lymphotropic virus to GD2 and simian virus 40 to GM3. Also, enhancement of the expression of GM2 on the cell membrane after cytomegalovirus infection has been reported. The objective of this study was to unveil the relationship between HSV-1 infection and the alteration of cellular ganglioside expression in neuronal and glial cell lines. In addition to these cell lines, several human tumor cell lines including astrocytoma cells, neuroblastoma cells, T-cell leukemia cells and kidney cells derived from normal human and monkey were infected with HSV-1 as well as HSV-2. To measure changes in ganglioside-related gene expressions and gangliosides levels in cells, quantitative PCR and glycosphingolipid-glycomic analysis were performed. Changes in gene expression of glycosyltransferases and sialyltransferases were observed in HSV-1- and HSV-2-infected cells, although with different trends. 39 glycosphingolipid-glycans were quantitatively analyzed. HSV-1 and HSV-2 infections resulted in changes in the total amount of gangliosides depending on the cell lines used and type of virus. Qualitative changes caused by each infection of HSV-1 and HSV-2 were almost negligible.
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- Aberrant expression of the pore-forming KATP channel subunit Kir6.2 in hippocampal reactive astrocytes in the 3xTg-AD mouse model and human Alzheimer's disease. [Journal Article]
- Neuroscience 2016 Aug 29; 336:81-101N
- Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by beta-amyloid (Aβ) deposition, neurofibrillary tangles and cognitive decline. Recent pharmacologic studies have fou...
Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by beta-amyloid (Aβ) deposition, neurofibrillary tangles and cognitive decline. Recent pharmacologic studies have found that ATP-sensitive potassium (KATP) channels may play a role in AD and could be a potential therapeutic target. Interestingly, these channels are found in both neurons and astrocytes. One of the hallmarks associated with AD is reactive gliosis and a change in astrocytic function has been identified in several neuropathological conditions including AD. Thus the goal of this study was to examine whether the pore-forming subunits of KATP channels, Kir6.1 and Kir6.2, are altered in the hippocampus in a cell type-specific manner of the 3xTg-AD mouse model of AD and in human AD tissue obtained from the Chinese brain bank. Specifically, in old 3xTg-AD mice, and age-matched controls, we examined glial fibrillary acidic protein (GFAP), glutamine synthetase (GS), Kir6.1 and Kir6.2 in hippocampal region CA1 with a combination of immunoblotting and immunohistochemistry (IHC). A time point was selected when memory impairment and histopathological changes have been reported to occur in 3xTg-AD mice. In human AD and age-matched control tissue IHC experiments were performed using GFAP and Kir6.2. In the hippocampus of 3xTg-AD mice, compared to wild-type controls, Western blots showed a significant increase in GFAP indicating astrogliosis. Further, there was an increase in Kir6.2, but not Kir6.1 in the plasma membrane fraction. IHC examination of hippocampal region CA1 in 3xTg-AD sections revealed an increase in Kir6.2 immunoreactivity (IR) in astrocytes as identified by GFAP and GS. In human AD tissue similar data were obtained. There was an increase in GFAP-IR in the stratum oriens (SO) and alveus (ALV) of CA1 concomitant with an increase in Kir6.2-IR in cells with an astrocytic-like morphology. Dual immunofluorescence revealed a dramatic increase in co-localization of Kir6.2-IR and GFAP-IR. Taken together, these data demonstrate that increased Kir6.2 is seen in reactive astrocytes in old 3xTg-AD mice and human AD tissue. These changes could dramatically alter astrocytic function and subsequently contribute to AD phenotype in either a compensatory or pathophysiological manner.