Regulation of gene expression by the TSPO ligand PK 11195
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE77998 | GEO | 2016/02/18
SECONDARY ACCESSION(S): PRJNA312316
REPOSITORIES: GEO
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Project description:We hypothesized that the potential ability of the 18 kDa mitochondrial translocator protein (TSPO) to regulate gene expression may underlie its numerous reported functions, ranging from mitochondrial activity till mental disorders. Therefore, we applied microarray analysis of gene expression to U118MG glioblastoma cells. Within 1 hr the TSPO ligand PK 11195 induced changes in expression of immediate early genes and transcription factors. After 24 hrs primarily gene expression for enzymes and other proteins is changed. The associated gene products are known to affect various cellular functions: programmed cell death, cell cycle, viability, proliferation, migration, differentiation, development, tumorigenesis, and inflammatory / immune responses. Our microscopic studies showed intense TSPO mitochondrial labeling but no TSPO signal in the cell nuclei. Thus, it appears that the TSPO is part of the retrograde mitochondrial-nuclear signaling pathway for modulation of gene expression and thereby may exert its numerous effects on cell function, phenotype, and disease. U118MG cells (1.255 à 106) were seeded in Petri dishes (i.e. 28.5 à 103 cells / cm2) and allowed to proliferate for 3 days in full medium. Experiments for gene expression assayed with microarray typically consisted of three experimental groups and a vehicle control group (n = 3 for each group). Serum deprived medium was applied for 24 hrs, in the experimental groups ending with the inclusion a choice of various PK 11195 exposures i.e. either 1 hr, 3 hrs, or 24 hrs. Exposure to PK 11195 implies serum deprived medium with 1% alcohol (vehicle) and PK 11195 (25 µM final concentration) for the required time period. 25 µM of PK 11195 is the optimal concentration for these types of experiments with U118MG cells (Kugler et al., 2008). The cells were collected by trypsinization, washed by centrifugation in phosphate buffered saline (PBS) (400 à g, 5 min), and lysed [RLT lysis buffer provided with the RNeasy Mini Kit diluted with β-mercaptoethanol (1 : 100)], according to the manufacturer's instructions. Lysates were stored at -70oC.
2016-02-18 | E-GEOD-77998 | biostudies-arrayexpress
Project description:It is known that application of TSPO ligands as well as knockdown of the mitochondrial 18 kDa translocator protein (TSPO) modulate viability, proliferation, adhesion, and migration of glioblastoma cells, as well as angiogenesis. To study the ability of the TSPO to regulate gene expression in relation to these functions we applied microarray analysis of gene expression to U118MG glioblastoma cells. Seen at the time points of 15, 30, and 45 minutes, the TSPO ligand PK 11195 induced changes in expression of immediate early genes and transcription factors. These changes also included gene products that are part of the canonical pathway for modulation of general gene expression. These changes peaked at 30 minutes. Thus, it appears that the TSPO is part of the retrograde mitochondrial-nuclear signaling pathway for modulation of gene expression. Consequently, our data indicate that this is a major venue whereby TSPO may drive its numerous functional effects. Keywords: modulation of nuclear gene expression, mitochondrial 18 kDa translocator protein (TSPO), TSPO ligand, PK 11195, 2-Cl-MGV-1, retrograde mitochondrial-nuclear signaling pathway, microscopy, mitochondria, cell nucleus abstract of annual meetingof the israel society for neuroscience, section B, abstract # 98.
2016-08-17 | GSE85697 | GEO
Project description:The mitochondrial translocator protein (TSPO) has been shown to bind cholesterol with high affinity and is involved in mediating its availability for steroidogenesis. We recently reported that targeted Tspo gene deletion in MA-10 mouse tumor Leydig cells resulted in reduced cAMP-stimulated steroid formation and significant reduction in the mitochondrial membrane potential (ΔΨm) compared to control cells. We hypothesized that ΔΨm reduction in the absence of TSPO probably reflects the dysregulation and/or maintenance failure of some basic mitochondrial function(s). To explore the consequences of TSPO depletion via CRISPR-Cas9-mediated deletion (indel) mutation in MA-10 cells, we assessed the transcriptome changes in TSPO-mutant versus wild-type (Wt) cells using RNA-seq. Gene expression profiles were validated using real-time PCR. We report herein that there are significant changes in nuclear gene expression in Tspo mutant versus Wt cells. The identified transcriptome changes were mapped to several signaling pathways including the regulation of membrane potential, calcium signaling, extracellular matrix, and phagocytosis. This is a retrograde signaling pathway from the mitochondria to the nucleus and is probably the result of changes in expression of several transcription factors, including key members of the NF-κB pathway. In conclusion, TSPO regulates nuclear gene expression through intracellular signaling. This is the first evidence of a compensatory response to the loss of TSPO with transcriptome changes at the cellular level.
2021-01-09 | GSE164481 | GEO
Project description:The 18-kDa translocator protein TSPO is a conserved ubiquitous high affinity cholesterol binding protein localized in the outer mitochondrial membrane. It plays a critical role in the segregation and transport of cholesterol from the outer to the inner mitochondrial membrane in steroidogenic cells. Imaging studies in humans, using specific TSPO ligands, showed that TSPO is highly expressed and accurately mirrors the histological picture of non-alcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH). However, the functions of TSPO in simple steatosis (SS) and NASH are unknown. In the present study, we examined the TSPO functions with in vivo NAFLD model. To induce NASH in vivo, we fed the WT and TSPO KO rat with MCD (methionine-choline deficient) diet. Loss of TSPO ameliorated the liver fibrosis through down regulation of bile acid synthesis by reduction of CYP7A1 and CYP27A1 and increase of farnesoid X receptor (FXR).
2021-04-04 | GSE138666 | GEO
Project description:Background: The mitochondrial protein, translocator protein (TSPO), is a widely used biomarker of neuroinflammation, but its non-selective cellular expression pattern implies roles beyond inflammatory processes. The present study investigated whether neuronal activity modifies TSPO expression in the adult central nervous system. Methods: Single-cell RNA sequencing was performed to generate a cellular landscape of basal TSPO gene expression in the hippocampus of adult (12 weeks old) C57BL6/N mice, whereas confocal laser scanning microscopy was used to verify TSPO protein in neuronal and non-neuronal cell populations. TSPO RNA and protein were quantified after stimulating neuronal activity with distinct stimuli, including designer receptors exclusively activated by designer drugs (DREADDs), exposure to a novel environment and acute treatment with the psychostimulant drug, amphetamine. Results: Single-cell RNA sequencing demonstrated a non-selective and multi-cellular gene expression pattern of TSPO at basal conditions in the adult mouse hippocampus. Confocal laser scanning microscopy confirmed that TSPO protein is expressed in neuronal and non-neuronal (astrocytes, microglia, vascular endothelial cells) cells of cortical (medial prefrontal cortex) and subcortical (hippocampus) brain regions. Stimulating neuronal activity through chemogenetic (DREADDs), physiological (novel environment exposure) or psychopharmacological (amphetamine treatment) approaches led to consistent increases in TSPO gene and protein levels in neurons but not in microglia or astrocytes. Conclusions: Neuronal activity has the potential to modify TSPO expression in the adult central nervous system. These findings challenge the general assumption that altered TSPO levels unequivocally mirrors ongoing neuroinflammation and emphasize the need to consider non-inflammatory interpretations in some physiological or pathological contexts.
2022-05-01 | GSE150508 | GEO
Project description:Translocator Protein (18kDa, TSPO) is a mitochondria outer membrane transmembrane protein and which expression is elevated during inflammation and injury. However, the exact function of TSPO is still controversial. Here, we constructed TSPO global knockout (KO) mice by Cre-LoxP system independently, which abolished TSPO protein expression in all tissues and shown normal phenotypes. The birth rate of TSPO heterozygote (Het)/Het breeding was consistent with the Mendel’s Law, suggesting a normal viability of TSPO KO mice at birth. RNAseq analysis showed no significant difference in the gene expression profile of lung tissues from TSPO KO mice compared with that of wild type mice, even the genes associated with bronchial alveoli immune homeostasis. The alveolar macrophage population was also not affected by TSPO deletion in the physiological condition. Our findings contradicts the results of Papadopoulos, but confirmed Selvaraj’s findings. This study reveals TSPO deficiency does not affect the viability and bronchial alveoli immune homeostasis.
2016-12-08 | GSE84942 | GEO
Project description:Glioblastoma is the most malignant and common type of primary brain tumor with a median survival of less than 21 months. It is particularly resistant to current immunotherapies. Thus, yet unknown mechanisms of immune resistance may be active in glioblastoma. Translocator protein 18 kDa (TSPO) expression is upregulated in glioblastoma and correlates with malignancy and poor prognosis but also with increased immune infiltration. An immunomodulatory role of TSPO in glioblastoma has not been reported. Here, we studied the role of TSPO in the regulation of immune resistance of human glioblastoma cells. We used public bulk and single-cell gene expression data to identify cell types, genes and signalling pathways correlating with TSPO expression. To validate inflammatory triggers and the role of TSPO experimentally, we co-cultured tumor-infiltrating T cells and cytotoxic T cell lines with autologous and antigen-loaded allogeneic, primary brain tumor initiating cells (BTICs). TSPO proficient and deficient BTIC lines and clones were generated through genetic manipulation. Inflammatory factors triggering TSPO expression were determined by ELISA and validated experimentally using blocking antibodies and recombinant proteins. The impact of TSPO on glioblastoma cell resistance against cytotoxic T cells was studied by cytotoxicity assays and by activity analysis of components of the apoptotic cascade. Individual death-inducing pathways suppressed by TSPO were determined using recombinant proteins and TSPO-regulated genes associated with apoptosis resistance were identified by gene expression analysis in TSPO proficient and deficient BTICs and subsequent functional analyses. TSPO expression in glioblastoma cells correlated with cytotoxic T cell infiltration, expression of TNFR and IFNGR, the activity of their downstream pathways, expression of TRAIL receptors and with PD-L1. Coculture of BTICs with tumor-reactive cytotoxic T cells or with T cell-derived factors induced TSPO up-regulation through TNFα and IFNγ. Silencing of TSPO sensitized BTICs against T cell-mediated cytotoxicity. TSPO protected BTICs selectively against TRAIL-induced apoptosis by regulating both intrinsic and extrinsic apoptosis pathways. TSPO regulated the expression of multiple genes associated with apoptosis-resistance of tumors. Among them, we studied the peptidase inhibitors PI3 and SLPI, which sensitized BTICs towards TRAIL-induced apoptosis. Our data revealed that TSPO expression in glioblastoma cells is induced through T cell derived cytokines IFNγ and TNFα. TSPO expression protects glioblastoma cells against cytotoxic T cell attack through the death inducing ligand TRAIL. Our data provided an indication that therapeutic targeting TSPO may be a suitable approach to sensitize glioblastoma to immune cell-mediated cytotoxicity by circumventing tumor intrinsic TRAIL-resistance.
2023-05-17 | GSE210654 | GEO
Project description:This study was intended to dissect the role of PBR/TSPO in hepatic metabolism. As it was determined that the purported role for PBR/TSPO in steroidogenesis was a misconception, the precise function and regulation of this therapeutic target remains a mystery. Via examining gene expression changes associated with PBR/TSPO deficiency in the liver, these results evaluate specific phenotypic perturbations linked to PBR/TSPO function.
2024-03-23 | GSE228098 | GEO
Project description:TSPO is a promising novel tracer target for positron-emission tomography (PET) imaging of brain tumors. However, due to the heterogeneity of cell populations that contribute to the TSPO-PET signal, imaging interpretation may be challenging. We therefore evaluated TSPO enrichment/expression in connection with its underlying histopathological and molecular features in gliomas. We analyzed TSPO expression and its regulatory mechanisms in large in silico datasets and by performing direct bisulfite sequencing of the TSPO promotor. In glioblastoma tissue samples of our TSPO-PET imaging study cohort, we dissected the association of TSPO tracer enrichment and protein labeling with the expression of cell lineage markers by immunohistochemistry and fluorescence multiplex stains. Furthermore, we identified relevant TSPO-associated signaling pathways by RNA sequencing. We found that TSPO expression is associated with prognostically unfavorable glioma phenotypes and that TSPO promotor hypermethylation is linked to IDH mutation. Careful histological analysis revealed that TSPO immunohistochemistry correlates with the TSPO-PET signal and that TSPO is expressed by diverse cell populations. While tumor core areas are the major contributor to the overall TSPO signal, TSPO signals in the tumor rim are mainly driven by CD68-positive microglia/macrophages. Molecularly, high TSPO expression marks prognostically unfavorable glioblastoma cell subpopulations characterized by an enrichment of mesenchymal gene sets and higher amounts of tumor-associated macrophages. In conclusion, our study improves the understanding of TSPO as an imaging marker in gliomas by unveiling IDH-dependent differences in TSPO expression/regulation, regional heterogeneity of the TSPO PET signal and functional implications of TSPO in terms of tumor immune cell interactions.
2023-09-14 | GSE230453 | GEO
Project description:Neuronal Activity Increases Translocator Protein (TSPO) Levels in the Adult Mouse Brain
| PRJNA632602 | ENA