Sustained PGC-1α2 or PGC-1α3 expression induces astrocyte dysfunction and degeneration.
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PROVIDER: PRJNA1044140 | ENA |
REPOSITORIES: ENA
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Project description:Peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α) transcriptional coactivators are key regulators of energy metabolism-related genes and are expressed in energy-demanding tissues. There are several PGC-1α variants with different biological functions in different tissues. The brain is one of the tissues where the role of PGC-1α isoforms remains less explored. Here, we used a toxin-based mouse model of Parkinson's disease (PD) and observed that the expression levels of variants PGC-1α2 and PGC-1α3 in the nigrostriatal pathway increases at the onset of dopaminergic cell degeneration. This increase occurs concomitant with an increase in glial fibrillary acidic protein levels. Since PGC-1α coactivators regulate cellular adaptive responses, we hypothesized that they could be involved in the modulation of astrogliosis induced by MPTP. Therefore, we analysed the transcriptome of astrocytes transduced with expression vectors encoding PGC-1α1 to 1α4 by massively parallel sequencing (RNA-seq) and identified the main cellular pathways controlled by these isoforms. Interestingly, in reactive astrocytes the inflammatory and antioxidant responses, adhesion, migration, and viability were altered by PGC-1α2 and PGC-1α3, showing that sustained expression of these isoforms induces astrocyte dysfunction and degeneration. This work highlights PGC-1α isoforms as modulators of astrocyte reactivity and potential therapeutic targets for the treatment of PD and other neurodegenerative disorders.
2023-11-27 | GSE248504 | GEO
Project description:Astrocytes contribute to the pathogenesis of multiple sclerosis (MS); however, the mechanisms underlying the regulation of astrocytic responses remain unknown. Here we report an exhaustive molecular and functional characterization of astrocyte reactivity following exposure to cerebrospinal fluid (CSF) from MS patients classified according to the degree of inflammatory activity. We showed that mouse astrocytes exposed to CSF from patients with high inflammatory activity (MS-High) exhibited a specific pro-inflammatory reactive state that was characterized by enhanced NF-kB signalling. This reactive astrocyte state conferred a dysfunctional response through an altered pro-inflammatory secretome that drove neuronal dysfunction and impaired synaptic plasticity. SerpinE1 was identified as a potential downstream mediator of the non-cell-autonomous toxic effect on neuronal function based on its significant up-regulation in secretomes from astrocytes exposed to CSF from MS-high patients. Further, we identified chitinase 3-like 1 as a potential upstream modulator of astrocyte reactivity via activation of NF-kB signalling based on its significantly increased levels in the CSF from MS-High patients. Taken together our findings indicate that the inflammatory microenvironment in the central nervous system of MS patients can induce specific reactive astrocyte states that trigger neuronal degeneration and may ultimately contribute to disease progression.
2022-06-23 | PXD027152 | Pride
Project description:The endoribonuclease, Dicer, is indispensible for generating the majority of mature microRNAs (miRNAs), which are posttranscriptional regulators of gene expression involved in a wide range of developmental and pathological processes in mammalian central nervous system. While functions of Dicer-dependent miRNA pathways in neurons and oligodendrocytes have been extensively investigated, little is known about the role of Dicer in astrocytes. Here we report the effect of Cre-loxP mediated conditional deletion of Dicer selectively from postnatal astroglia on brain development. Dicer-deficient mice exhibited normal motor development and neurological morphology prior to postnatal week 5. Thereafter mutant mice invariably developed a rapidly fulminant neurological decline characterized by ataxia, severe progressive cerebellar degeneration, seizures, uncontrollable movements and premature death by postnatal week 9-10. Integrated transcription profiling, histological and functional analyses of cerebella showed that deletion of Dicer in cerebellar astrocytes altered the transcriptome of astrocytes to be more similar to an immature or reactive-like state prior to the onset of neurological symptoms or morphological changes. As a result, critical and mature astrocytic functions including glutamate uptake and antioxidant pathways were substantially impaired, leading to massive apoptosis of cerebellar granule cells and degeneration of Purkinje cells. Collectively, our study demonstrates the critical involvement of Dicer in normal astrocyte maturation and maintenance. Our findings also reveal non-cell autonomous roles of astrocytic Dicer-dependent pathways in regulating proper neuronal functions and implicate that loss of or dysregulation of astrocytic Dicer-dependent pathways may be involved in neurodegeneration and other neurological disorders. Four replicate experiments using samples derived from biologically independent pairs of control (mGfap-Cre; Dicer +/flox) and Dicer mutant (mGfap-Cre; Dicer flox/flox) littermate mice (postnatal day 30) were performed with a dye-swap experimental design.
2011-05-10 | E-GEOD-28589 | biostudies-arrayexpress
Project description:Glaucoma is an optic neuropathy characterized by progressive degeneration of retinal ganglion cells (RGCs) and visual loss. Previous studies have reported that the variation of the ATP-binding cassette transporter 1 (ABCA1) gene is linked to a higher risk of glaucoma in humans, but the pathological mechanisms remain unknown. Here we report that ABCA1 loss, especially in astrocytes, causes optic neuropathy. ABCA1 was mainly expressed in astrocytes rather than neurons, and that knockout of Abca1 gene under GFAP promoter (Glia-KO) caused age-associated RGC degeneration and ocular dysfunction without affecting intraocular pressure, a major risk factor for glaucoma. Glia-KO mice showed age-associated changes in astrocyte reactivity accompanied by the accumulation of cholesterol, a major substrate of ABCA1. Single-cell RNA sequencing revealed that Abca1 deficiency causes astrocyte-triggered inflammation and increased sensitivity of RGCs against excitotoxicity. Altogether, these findings suggest that astrocytic dysfunction caused by ABCA1 loss triggers age-associated optic neuropathy-like pathology.
2022-07-11 | GSE207929 | GEO
Project description:Glaucoma is an optic neuropathy characterized by progressive degeneration of retinal ganglion cells (RGCs) and visual loss. Previous studies have reported that the variation of the ATP-binding cassette transporter 1 (ABCA1) gene is linked to a higher risk of glaucoma in humans, but the pathological mechanisms remain unknown. Here we report that ABCA1 loss, especially in astrocytes, causes optic neuropathy. ABCA1 was mainly expressed in astrocytes rather than neurons, and that knockout of Abca1 gene under GFAP promoter (Glia-KO) caused age-associated RGC degeneration and ocular dysfunction without affecting intraocular pressure, a major risk factor for glaucoma. Glia-KO mice showed age-associated changes in astrocyte reactivity accompanied by the accumulation of cholesterol, a major substrate of ABCA1. Single-cell RNA sequencing revealed that Abca1 deficiency causes astrocyte-triggered inflammation and increased sensitivity of RGCs against excitotoxicity. Altogether, these findings suggest that astrocytic dysfunction caused by ABCA1 loss triggers age-associated optic neuropathy-like pathology.
2022-07-11 | GSE207928 | GEO
Project description:Failed regeneration of myelin around neuronal axons following central nervous system damage contributes to nerve dysfunction and clinical decline in various neurological conditions, for which there is an unmet therapeutic demand. Here, we show that interaction between glial cells – astrocytes and mature myelin-forming oligodendrocytes – is a critical determinant of remyelination. Using in vivo/ ex vivo/ in vitro rodent models and human brain lesion analyses, we discover that astrocytes support the survival of regenerating oligodendrocytes, via downregulation of the Nrf2 pathway associated with increased astrocytic cholesterol biosynthesis pathway activation. Remyelination fails following sustained astrocytic Nrf2 activation in focally-lesioned mice yet is restored by either cholesterol biosynthesis/efflux stimulation, or Nrf2 inhibition using the existing therapeutic Luteolin. We identify that astrocyte-oligodendrocyte interaction regulates remyelination, and reveal a drug strategy for central nervous system regeneration centred on targeting this interaction.
2023-05-17 | PXD041850 | Pride
Project description:The peroxisome proliferator-activated receptor c coactivator 1 (PGC-1) proteins are key regulators of cellular bioenergetics and are accordingly expressed in tissues with a high energetic demand. For example, PGC-1a and PGC-1b control organ function of brown adipose tissue, heart, brain, liver and skeletal muscle. Surprisingly, despite their prominent role in the control of mitochondrial biogenesis and oxidative metabolism, expression and function of the PGC-1 coactivators in the retina, an organ with one of the highest energy demands per tissue weight, are completely unknown. Moreover, the molecular mechanisms that coordinate energy production with repair processes in the damaged retina remain enigmatic. In the present study, we thus investigated the expression and function of the PGC-1 coactivators in the healthy and the damaged retina. We show that PGC-1a and PGC-1b are found at high levels in different structures of the mouse retina, most prominently in the photoreceptors. Furthermore, PGC-1a knockout mice suffer from a striking deterioration in retinal morphology and function upon detrimental light exposure. Gene expression studies revealed dysregulation of all major pathways involved in retinal damage and apoptosis, repair and renewal in the PGC-1a knockouts. The light-induced increase in apoptosis in vivo in the absence of PGC-1a was substantiated in vitro, where overexpression of PGC-1a evoked strong anti-apoptotic effects. Finally, we found that retinal levels of PGC-1 expression are reduced in different mouse models for retinitis pigmentosa. We demonstrate that PGC-1a is a central coordinator of energy production and, importantly, all of the major processes involved in retinal damage and subsequent repair. Together with the observed dysregulation of PGC-1a and PGC-1b in retinitis pigmentosa mouse models, these findings thus imply that PGC-1a might be an attractive target for therapeutic approaches aimed at retinal degeneration diseases.
2016-04-15 | GSE80265 | GEO
Project description:PGC-1α (Peroxisome proliferator-activated receptor gamma coactivator-1alpha) coactivators regulate adaptive gene expression in response to challenges such as cold exposure, fasting, or physical exercise to balance energy supply and demand. Transcription of a single PGC-1α gene produces different isoforms (e.g. PGC-1α1 to α4) with different biological functions. We aimed to characterize the nuclear interactome for each PGC-1α variant, in particular the transcription factors they bind to regulate gene expression. This was done by generating GST-fusions of all PGC-1a variants, expressed in an insect cell system. These were used to capture associated protein complexes from HeLa nuclear extracts.
2022-03-01 | PXD009232 | Pride
Project description:To elucidate the role(s) of WNT/CTNNB1 signaling in the testis, transgenic Ctnnb1 tm1Mmt/+;Amhr2 tm3(cre)Bhr/+ mice were generated to obtain sustained activation of the WNT/CTNNB1 pathway in Sertoli cells. Male Ctnnb1 tm1Mmt/+;Amhr2 tm3(cre)Bhr/+ mice were sterile because of testicular atrophy starting at 5 wk of age, associated with degeneration of seminiferous tubules and the progressive loss of germ cells. Sustained WNT/CTNNB1 pathway activation was obtained in Ctnnb1 tm1Mmt/+;Amhr2 tm3(cre)Bhr/+ Sertoli cells. Sertoli cells often exhibited morphological characteristics suggestive of incomplete differentiation that appeared in a manner coincident with germ cell loss, accompanied by an increase in the expression of the immature Sertoli cell marker AMH. Microarray analyses performed on cultured Sertoli cells showed that CTNNB1 induces the expression of genes associated with the female sex determination pathway as well as cell-cycle associated genes . Together, these data suggest that the WNT/CTNNB1 pathway regulates Sertoli cell functions critical to their capacity to support spermatogenesis and to proliferate in the postnatal testis. Sertoli cells were obtained from 3wks-old Ctnnb1(tm1Mmt/tm1Mmt) mice. Cells were infected with adenoviruses to express eGFP or Cre in serum-free medium, and subsequently harvested for RNA extraction. Preliminary experiments demonstrated that an infection efficiency of nearly 100% could be obtained at an MOI of 50 (as determined by analysis of fluorescent signal in Ad-eGFP-infected cells) and that the Ad-Cre virus produced complete recombination of the floxed Ctnnb1 allele after 12 hours. Microaaray analyses were done using triplicate RNA samples from each adenoviral treatment using MouseRef-6 v.2.0 expression BeadChips technology (Illumina, San Diego, CA).
2011-04-05 | E-GEOD-28402 | biostudies-arrayexpress
Project description:Background: Astrocytes regulate neuronal function, synaptic formation and maintenance partly through secreted extracellular vesicles (EVs). In amyotrophic lateral sclerosis (ALS) astrocytes display a toxic phenotype that contributes to motor neuron (MN) degeneration. Methods: We used human induced astrocytes (iAstrocytes) from 3 ALS patients carrying C9orf72 mutations and 3 non-affected donors to investigate the role of astrocyte-derived EVs (ADEVs) in ALS astrocyte toxicity. ADEVs were isolated from iAstrocyte conditioned medium via ultracentrifugation and resuspended in fresh astrocyte medium before testing ADEV impact on HB9-GFP+ mouse motor neurons (Hb9-GFP+ MN). We used post-mortem brain and spinal cord tissue from 3 sporadic ALS and 3 non-ALS cases for PCR analysis. Findings: We report that EV formation and miRNA cargo are dysregulated in C9ORF72-ALS iAstrocytes and this affects neurite network maintenance and MN survival in vitro. In particular, we have identified downregulation of miR-494-3p, a negative regulator of semaphorin 3A (SEMA3A). We show here that by restoring miR-494-3p levels through expression of an engineered miRNA mimic we can downregulate Sema3A levels in MNs and increases MN survival in vitro. Consistently, we also report lower levels of mir-494-3p and higher levels of SEMA3A in cortico-spinal tract tissue isolated from sporadic ALS donors, thus demonstrating the pathological importance of this pathway in MNs and its therapeutic potential. Interpretation: ALS ADEVs and their miRNA cargo are involved in MN death in ALS and we have identified miR-494-3p as a potential therapeutic target.
2019-01-08 | GSE122640 | GEO