Brain ischemic injury represents one of the greatest medical challenges for the aging population in developed countries, yet despite strong efforts, possibilities to treat ischemic injury still remain poor. Stroke, the most common type of brain ischemic injury in humans, is caused by brain artery occlusion, and represents a focal form of ischemia, which leads to neuronal loss in the ischemic core, and glial scar formation in the penumbral region around the core. Such glial scar mainly comprises reactive astrocytes, reactive NG2 glia and activated microglia. Reactive astrocytes display distinct features when compared to healthy astroglia, including changes in their morphology, metabolism, gene expression profiles, production of extracellular matrix proteins or proliferation rate. Similarly to astrocytes in the healthy nervous tissue, reactive astrocytes surrounding the glial scar strongly influence the activity of surviving neurons around the ischemic lesion. Bringing insight into pathophysiological functions of reactive astrocytes within the glial scar might thus open new possibilities for stroke treatment. Here, we summarize the properties of reactive astrocytes, with emphasis on the expression and function of ion channels, transporters and neurotransmitter receptors; all of which possess the ability to change the functional state of astrocytes, such as the membrane equilibrium potentials for different ions. This may have major effects on the functioning of surviving neurons, consequently leading to changes in neuronal excitability and progression of secondary pathologies, such as epilepsy. Moreover, we provide possible clues for therapy, based on functional modulation of astrocytic ion transporting mechanisms.

• Klíčová slova
• Reactive astrocytes, brain ischemia, glutamate homeostasis, ion channels, potassium buffering, transporters,
• MeSH
• astrocyty účinky léků   metabolismus   MeSH
• glióza farmakoterapie   metabolismus   MeSH
• homeostáza účinky léků   fyziologie   MeSH
• iontové kanály antagonisté a inhibitory   metabolismus   MeSH
• ischemie mozku farmakoterapie   metabolismus   MeSH
• lidé MeSH
• neurony účinky léků   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• iontové kanály MeSH

NG2 cells, a fourth glial cell type in the adult mammalian central nervous system, produce oligodendrocytes in the healthy nervous tissue, and display wide differentiation potential under pathological conditions, where they could give rise to reactive astrocytes. The factors that control the differentiation of NG2 cells after focal cerebral ischemia (FCI) are largely unknown. Here, we used transgenic Cspg4-cre/Esr1/ROSA26Sortm14(CAG-tdTomato) mice, in which tamoxifen administration triggers the expression of red fluorescent protein (tomato) specifically in NG2 cells and cells derived therefrom. Differentiation potential (in vitro and in vivo) of tomato-positive NG2 cells from control or postischemic brains was determined using the immunohistochemistry, single cell RT-qPCR and patch-clamp method. The ischemic injury was induced by middle cerebral artery occlusion, a model of FCI. Using genetic fate-mapping method, we identified sonic hedgehog (Shh) as an important factor that influences differentiation of NG2 cells into astrocytes in vitro. We also manipulated Shh signaling in the adult mouse brain after FCI. Shh signaling activation significantly increased the number of astrocytes derived from NG2 cells in the glial scar around the ischemic lesion, while Shh signaling inhibition caused the opposite effect. Since Shh signaling modifications did not change the proliferation rate of NG2 cells, we can conclude that Shh has a direct influence on the differentiation of NG2 cells and therefore, on the formation and composition of a glial scar, which consequently affects the degree of the brain damage. GLIA 2016;64:1518-1531.

• Klíčová slova
• NG2 cells, astrocytes, glial scar, ischemia, sonic hedgehog,
• MeSH
• astrocyty metabolismus   MeSH
• buněčná diferenciace fyziologie   MeSH
• ischemie mozku patologie   MeSH
• mozek cytologie   MeSH
• myši MeSH
• neuroglie metabolismus   MeSH
• oligodendroglie metabolismus   MeSH
• počet buněk MeSH
• poranění mozku patologie   MeSH
• proteiny hedgehog metabolismus   MeSH
• signální transdukce MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• proteiny hedgehog MeSH
• Shh protein, mouse MeSH Prohlížeč

The term neuroinflammation defines the reactions of astrocytes and microglia to alterations in homeostasis in the diseased central nervous system (CNS), the exacerbation of which contributes to the neurodegenerative effects of Alzheimer's disease (AD). Local environmental conditions, such as the presence of proinflammatory molecules, mechanical properties of the extracellular matrix (ECM), and local cell-cell interactions, are determinants of glial cell phenotypes. In AD, the load of the cytotoxic/proinflammatory amyloid β (Aβ) peptide is a microenvironmental component increasingly growing in the CNS, imposing time-evolving challenges on resident cells. This study aimed to investigate the temporal and spatial variations of the effects produced by this process on astrocytes and microglia, either directly or by interfering in their interactions. Ex vivo confocal analyses of hippocampal sections from the mouse model TgCRND8 at different ages have shown that overproduction of Aβ peptide induced early and time-persistent disassembly of functional astroglial syncytium and promoted a senile phenotype of reactive microglia, hindering Aβ clearance. In the late stages of the disease, these patterns were altered in the presence of Aβ-plaques, surrounded by typically reactive astrocytes and microglia. Morphofunctional characterization of peri-plaque gliosis revealed a direct contribution of astrocytes in plaque buildup that might result in shielding Aβ-peptide cytotoxicity and, as a side effect, in exacerbating neuroinflammation.

• Klíčová slova
• Aβ-aggregates, amyloid plaques, cell–cell interactions, clasmatodendrosis, confocal microscopy, glial cells, hippocampus, neurodegeneration, neuroinflammation, transgenic mouse,
• MeSH
• Alzheimerova nemoc * genetika   MeSH
• amyloidní beta-protein MeSH
• amyloidní plaky MeSH
• astrocyty MeSH
• centrální nervový systém MeSH
• myši transgenní MeSH
• myši MeSH
• neurozánětlivé nemoci MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• amyloidní beta-protein MeSH

Astrocytes respond to ischemic brain injury by proliferation, the increased expression of intermediate filaments and hypertrophy, which results in glial scar formation. In addition, they alter the expression of ion channels, receptors and transporters that maintain ionic/neurotransmitter homeostasis. Here, we aimed to demonstrate the expression of Hcn1-4 genes encoding hyperpolarization-activated cyclic nucleotide-gated (HCN) channels in reactive astrocytes following focal cerebral ischemia (FCI) or global cerebral ischemia (GCI) and to characterize their functional properties. A permanent occlusion of the middle cerebral artery (MCAo) was employed to induce FCI in adult GFAP/EGFP mice, while GCI was induced by transient bilateral common carotid artery occlusion combined with hypoxia in adult rats. Using FACS, we isolated astrocytes from non-injured or ischemic brains and performed gene expression profiling using single-cell RT-qPCR. We showed that 2 weeks after ischemia reactive astrocytes express high levels of Hcn1-4 transcripts, while immunohistochemical analyses confirmed the presence of HCN1-3 channels in reactive astrocytes 5 weeks after ischemia. Electrophysiological recordings revealed that post-ischemic astrocytes are significantly depolarized, and compared with astrocytes from non-injured brains, they display large hyperpolarization-activated inward currents, the density of which increased 2-3-fold in response to ischemia. Their activation was facilitated by cAMP and their amplitudes were decreased by ZD7288 or low extracellular Na(+) concentration, suggesting that they may belong to the family of HCN channels. Collectively, our results demonstrate that regardless of the type of ischemic injury, reactive astrocytes express HCN channels, which could therefore be an important therapeutic target in poststroke therapy.

• Klíčová slova
• HCN channels, ZD7288, astrocytes, cortex, focal and global cerebral ischemia, hippocampus,
• MeSH
• AMP cyklický farmakologie   MeSH
• astrocyty účinky léků   metabolismus   MeSH
• gliový fibrilární kyselý protein genetika   metabolismus   MeSH
• ischemie patologie   MeSH
• kationtové kanály řízené cyklickými nukleotidy genetika   metabolismus   MeSH
• krysa rodu Rattus MeSH
• membránové potenciály účinky léků   fyziologie   MeSH
• modely nemocí na zvířatech MeSH
• mozek cytologie   MeSH
• myši transgenní MeSH
• myši MeSH
• neurony účinky léků   metabolismus   MeSH
• potkani Wistar MeSH
• proteiny nervové tkáně genetika   metabolismus   MeSH
• pyrimidiny farmakologie   MeSH
• regulace genové exprese účinky léků   fyziologie   MeSH
• sodík metabolismus   MeSH
• techniky in vitro MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• AMP cyklický MeSH
• gliový fibrilární kyselý protein MeSH
• ICI D2788 MeSH Prohlížeč
• kationtové kanály řízené cyklickými nukleotidy MeSH
• proteiny nervové tkáně MeSH
• pyrimidiny MeSH
• sodík MeSH

The glycoprotein clusterin (CLU) is involved in cell proliferation and DNA damage repair and is highly expressed in tumor cells. Here, we aimed to investigate the effects of CLU dysregulation on two human astrocytic cell lines: CCF-STTG1 astrocytoma cells and SV-40 immortalized normal human astrocytes. We observed that suppression of CLU expression by RNA interference inhibited cell proliferation, triggered the DNA damage response, and resulted in cellular senescence in both cell types tested. To further investigate the underlying mechanism behind these changes, we measured reactive oxygen species, assessed mitochondrial function, and determined selected markers of the senescence-associated secretory phenotype. Our results suggest that CLU deficiency triggers oxidative stress-mediated cellular senescence associated with pronounced alterations in mitochondrial membrane potential, mitochondrial mass, and expression levels of OXPHOS complex I, II, III and IV, indicating mitochondrial dysfunction. This report shows the important role of CLU in cell cycle maintenance in astrocytes. Based on these data, targeting CLU may serve as a potential therapeutic approach valuable for treating gliomas.

• Klíčová slova
• Astrocytes, Cellular senescence, Clusterin, Mitochondria, Oxidative stress,
• MeSH
• astrocyty * metabolismus   patologie   MeSH
• klusterin * nedostatek   metabolismus   MeSH
• lidé MeSH
• membránový potenciál mitochondrií MeSH
• mitochondrie metabolismus   MeSH
• nádorové buněčné linie MeSH
• oxidační stres MeSH
• oxidativní fosforylace MeSH
• poškození DNA MeSH
• proliferace buněk MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• stárnutí buněk * fyziologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• CLU protein, human MeSH Prohlížeč
• klusterin * MeSH
• reaktivní formy kyslíku MeSH

AIM: Astrocytes respond to stressors by acquiring a reactive state characterized by changes in their morphology and function. Molecules underlying reactive astrogliosis, however, remain largely unknown. Given that several studies observed increase in the Amyloid Precursor Protein (APP) in reactive astrocytes, we here test whether APP plays a role in reactive astrogliosis. METHODS: We investigated whether APP instigates reactive astroglios by examining in vitro and in vivo the morphology and function of naive and APP-deficient astrocytes in response to APP and well-established stressors. RESULTS: Overexpression of APP in cultured astrocytes led to remodeling of the intermediate filament network, enhancement of cytokine production, and activation of cellular programs centered around the interferon (IFN) pathway, all signs of reactive astrogliosis. Conversely, APP deletion abrogated remodeling of the intermediate filament network and blunted expression of IFN-stimulated gene products in response to lipopolysaccharide. Following traumatic brain injury (TBI), mouse reactive astrocytes also exhibited an association between APP and IFN, while APP deletion curbed the increase in glial fibrillary acidic protein observed canonically in astrocytes in response to TBI. CONCLUSIONS: The APP thus represents a candidate molecular inducer and regulator of reactive astrogliosis. This finding has implications for understanding pathophysiology of neurodegenerative and other diseases of the nervous system characterized by reactive astrogliosis and opens potential new therapeutic avenues targeting APP and its pathways to modulate reactive astrogliosis.

• Klíčová slova
• amyloid precursor protein, astrocytes, interferon pathway, lipopolysaccharide, reactive astrogliosis, traumatic brain injury,
• MeSH
• amyloidový prekurzorový protein beta * metabolismus   genetika   MeSH
• astrocyty * metabolismus   patologie   MeSH
• glióza * metabolismus   patologie   MeSH
• kultivované buňky MeSH
• myši inbrední C57BL MeSH
• myši knockoutované MeSH
• myši MeSH
• traumatické poranění mozku metabolismus   patologie   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• amyloidový prekurzorový protein beta * MeSH

We present in vitro and in vivo evidence demonstrating that Amyloid Precursor Protein (APP) acts as an essential instigator of reactive astrogliosis. Cell-specific overexpression of APP in cultured astrocytes led to remodelling of the intermediate filament network, enhancement of cytokine production and activation of cellular programs centred around the interferon (IFN) pathway, all signs of reactive astrogliosis. Conversely, APP deletion in cultured astrocytes abrogated remodelling of the intermediate filament network and blunted expression of IFN stimulated gene (ISG) products in response to lipopolysaccharide (LPS). Following traumatic brain injury (TBI), mouse reactive astrocytes also exhibited an association between APP and IFN, while APP deletion curbed the increase in glial fibrillary acidic protein (GFAP) observed canonically in astrocytes in response to TBI. Thus, APP represents a molecular inducer and regulator of reactive astrogliosis.

• Klíčová slova
• amyloid precursor protein, astrocytes, interferon pathway, lipopolysaccharide, reactive astrogliosis, traumatic brain injury,
• Publikační typ
• časopisecké články MeSH
• preprinty MeSH

Reactive astrogliosis is a reaction of astrocytes to disturbed homeostasis in the central nervous system (CNS), accompanied by changes in astrocyte numbers, morphology, and function. Reactive astrocytes are important in the onset and progression of many neuropathologies, such as neurotrauma, stroke, and neurodegenerative diseases. Single-cell transcriptomics has revealed remarkable heterogeneity of reactive astrocytes, indicating their multifaceted functions in a whole spectrum of neuropathologies, with important temporal and spatial resolution, both in the brain and in the spinal cord. Interestingly, transcriptomic signatures of reactive astrocytes partially overlap between neurological diseases, suggesting shared and unique gene expression patterns in response to individual neuropathologies. In the era of single-cell transcriptomics, the number of new datasets steeply increases, and they often benefit from comparisons and integration with previously published work. Here, we provide an overview of reactive astrocyte populations defined by single-cell or single-nucleus transcriptomics across multiple neuropathologies, attempting to facilitate the search for relevant reference points and to improve the interpretability of new datasets containing cells with signatures of reactive astrocytes.

• Klíčová slova
• CNS diseases, astrocytes, cell populations, neurodegeneration, neuroinflammation, reactive astrogliosis, single-cell RNA-seq,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Tuberous sclerosis complex (TSC) is a genetic disease presenting with multiple neurological symptoms including epilepsy, mental retardation, and autism. Abnormal activation of various inflammatory pathways has been observed in astrocytes in brain lesions associated with TSC. Increasing evidence supports the involvement of microRNAs in the regulation of astrocyte-mediated inflammatory response. To study the role of inflammation-related microRNAs in TSC, we employed real-time PCR and in situ hybridization to characterize the expression of miR21, miR146a, and miR155 in TSC lesions (cortical tubers and subependymal giant cell astrocytomas, SEGAs). We observed an increased expression of miR21, miR146a, and miR155 in TSC tubers compared with control and perituberal brain tissue. Expression was localized in dysmorphic neurons, giant cells, and reactive astrocytes and positively correlated with IL-1β expression. In addition, cultured human astrocytes and SEGA-derived cell cultures were used to study the regulation of the expression of these miRNAs in response to the proinflammatory cytokine IL-1β and to evaluate the effects of overexpression or knockdown of miR21, miR146a, and miR155 on inflammatory signaling. IL-1β stimulation of cultured glial cells strongly induced intracellular miR21, miR146a, and miR155 expression, as well as miR146a extracellular release. IL-1β signaling was differentially modulated by overexpression of miR155 or miR146a, which resulted in pro- or anti-inflammatory effects, respectively. This study provides supportive evidence that inflammation-related microRNAs play a role in TSC. In particular, miR146a and miR155 appear to be key players in the regulation of astrocyte-mediated inflammatory response, with miR146a as most interesting anti-inflammatory therapeutic candidate.

• Klíčová slova
• astrocytes, cultures, inflammation, microRNA, subependymal giant cell astrocytoma, tuberous sclerosis complex,
• MeSH
• astrocytom metabolismus   patologie   MeSH
• astrocyty metabolismus   MeSH
• buněčné kultury MeSH
• dítě MeSH
• dospělí MeSH
• kojenec MeSH
• kultivované buňky MeSH
• lidé středního věku MeSH
• lidé MeSH
• mikro RNA metabolismus   MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mozek metabolismus   MeSH
• neurony metabolismus   MeSH
• předškolní dítě MeSH
• signální transdukce fyziologie   MeSH
• tuberózní skleróza metabolismus   MeSH
• Check Tag
• dítě MeSH
• dospělí MeSH
• kojenec MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• předškolní dítě MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• mikro RNA MeSH
• MIRN146 microRNA, human MeSH Prohlížeč
• MIRN155 microRNA, human MeSH Prohlížeč
• MIRN21 microRNA, human MeSH Prohlížeč

Astrocytes perform control and regulatory functions in the central nervous system; heterogeneity among them is still a matter of debate due to limited knowledge of their gene expression profiles and functional diversity. To unravel astrocyte heterogeneity during postnatal development and after focal cerebral ischemia, we employed single-cell gene expression profiling in acutely isolated cortical GFAP/EGFP-positive cells. Using a microfluidic qPCR platform, we profiled 47 genes encoding glial markers and ion channels/transporters/receptors participating in maintaining K(+) and glutamate homeostasis per cell. Self-organizing maps and principal component analyses revealed three subpopulations within 10-50 days of postnatal development (P10-P50). The first subpopulation, mainly immature glia from P10, was characterized by high transcriptional activity of all studied genes, including polydendrocytic markers. The second subpopulation (mostly from P20) was characterized by low gene transcript levels, while the third subpopulation encompassed mature astrocytes (mainly from P30, P50). Within 14 days after ischemia (D3, D7, D14), additional astrocytic subpopulations were identified: resting glia (mostly from P50 and D3), transcriptionally active early reactive glia (mainly from D7) and permanent reactive glia (solely from D14). Following focal cerebral ischemia, reactive astrocytes underwent pronounced changes in the expression of aquaporins, nonspecific cationic and potassium channels, glutamate receptors and reactive astrocyte markers.

• MeSH
• antigeny genetika   metabolismus   MeSH
• astrocyty metabolismus   MeSH
• gliový fibrilární kyselý protein genetika   metabolismus   MeSH
• imunohistochemie MeSH
• mozková kůra cytologie   metabolismus   MeSH
• myši transgenní MeSH
• myši MeSH
• neuroglie cytologie   metabolismus   MeSH
• polymerázová řetězová reakce MeSH
• proteoglykany genetika   metabolismus   MeSH
• průtoková cytometrie MeSH
• S-100 kalcium vázající protein G, podjednotka beta genetika   metabolismus   MeSH
• zelené fluorescenční proteiny genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antigeny MeSH
• chondroitin sulfate proteoglycan 4 MeSH Prohlížeč
• enhanced green fluorescent protein MeSH Prohlížeč
• gliový fibrilární kyselý protein MeSH
• proteoglykany MeSH
• S-100 kalcium vázající protein G, podjednotka beta MeSH
• zelené fluorescenční proteiny MeSH