Project description:Analysis of the effects of ATM loss on gene expression to identify causes of neurodegeneration. ATM levels were reduced ubiquitously via the temperature-sensitive ATM^8 allele, or via tissue-specific RNAi of ATM (ATMi) using the Gal4/UAS expression system in neurons (Elav-GAL4 and ElavC155-GAL4) or glial cells (Repo-GAL4).
Project description:Analysis of the effects of ATM loss on gene expression to identify causes of neurodegeneration. ATM levels were reduced ubiquitously via the temperature-sensitive ATM^8 allele, or via tissue-specific RNAi of ATM (ATMi) using the Gal4/UAS expression system in neurons (Elav-GAL4 and ElavC155-GAL4) or glial cells (Repo-GAL4). A 20-chip study using total RNA representing 2 replicates of 3 control genotypes (ATM^8/+, Repo-GAL4, and ElavC155-GAL4) and 3 experimental genotypes (ATM^8/ATM^8, Repo-ATMi, ElavC155-ATMi), and 4 replicates each of a control (Elav-GAL4) and experimental (Elav-ATMi) genotype
Project description:The symptoms of ataxia-telangiectasia (A-T) include a progressive neurodegeneration caused by ATM protein deficiency. We previously found that nuclear accumulation of histone deacetylase-4, HDAC4, contributes to this degeneration; we now report that increased histone H3K27 trimethylation (H3K27me3) mediated by polycomb repressive complex 2 (PRC2) also plays an important role in the A-T phenotype. Enhancer of zeste homolog 2 (EZH2), a core catalytic component of PRC2, is identified as a new ATM kinase target, and its S734 phosphorylation reduces protein stability. Thus, PRC2 formation is elevated along with H3K27me3in ATM deficiency. ChIP-sequencing shows a significant increase in H3K27me3 ‘marks’ and a dramatic shift in their location. The change of H3K27me3 chromatin-binding pattern is directly related to cell cycle re-entry and cell death of ATM-deficient neurons. Lentiviral knockdown of EZH2 rescues Purkinje cell degeneration and behavioral abnormalities in Atm / mice, demonstrating that EZH2-mediated H3K27me3 is another key factor in A-T neurodegeneration. Two samples each were run of brain total RNA from Atm+/+ and Atm-/- mice.
Project description:A loss of the checkpoint kinase ATM leads to impairments in the DNA damage response, and in humans causes cerebellar neurodegeneration, and a high risk to cancer. A loss of ATM is also associated with increased protein aggregation. The relevance and characteristics of this aggregation are still incompletely understood. Moreover, it is unclear to what extent other genotoxic conditions can trigger protein aggregation as well. Here, we show that targeting ATM, but also ATR or DNA topoisomerases result in a similar, widespread aggregation of a metastable, disease-associated subfraction of the proteome. Aggregation-prone model substrates, including expanded polyglutamine repeats, aggregate faster under these conditions. This increased aggregation results from an overload of chaperone systems, which lowers the cell-intrinsic threshold for proteins to aggregate. In line with this, we find that inhibition of the HSP70 chaperone system further exacerbates the increased protein aggregation. Moreover, we identify the molecular chaperone HSPB5 as a potent suppressor of it. Our findings reveal that various genotoxic conditions trigger protein aggregation, in a manner that is highly reminiscent of the widespread aggregation occurring in situations of proteotoxic stress and in proteinopathies.
Project description:In cerebellar atrophy of 12-month-old ATM-null mice, transcriptome upregulations concern most neurotransmission and neuropeptide pathways, while downregulations affect prominently Itpr1, Usp2 and non-coding RNA In cerebellar atrophy of 12-month-old ATM-null mice, transcriptome upregulations concern most neurotransmission and neuropeptide pathways, while downregulations affect prominently Itpr1, Usp2 and non-coding RNA The autosomal recessive disorder Ataxia-Telangiectasia is caused by dysfunction of stress response protein ATM. In the nucleus of proliferating cells, ATM senses DNA double-strand breaks and coordinates their repair. This role explains T-cell dysfunction and tumor risk. However, it remains unclear whether this function is relevant for postmitotic neurons and underlies the cerebellar atrophy, since ATM is cytoplasmic in postmitotic neurons. Here, we used ATM-null mice that survived early immune deficits by bone-marrow transplantation, and reached initial neurodegeneration stages at 12 months of age. Global cerebellar transcriptomics demonstrated ATM depletion to trigger upregulations in most neurotransmission and neuropeptide systems. Downregulated transcripts were found for the ATM interactome component Usp2, many non-coding RNAs, ataxia genes Itpr1, Grid2, immediate early genes and immunity factors. Allelic splice changes affected prominently neuropeptide machinery, e.g. Oprm1. Validation experiments with stressors were performed in human neuroblastoma cells, where ATM localized only to cytoplasm, similar to brain. Effect confirmation in SH-SY5Y cells occurred better after ATM depletion and osmotic stress better than nutrient / oxidative stress, rather than ATM kinase inhibition or DNA stressor bleomycin. Overall, we provide pioneer observations from a faithful A-T mouse model, which suggest general changes in synaptic and dense-core vesicle stress adaptation.
Project description:The symptoms of ataxia-telangiectasia (A-T) include a progressive neurodegeneration caused by ATM protein deficiency. We previously found that nuclear accumulation of histone deacetylase-4, HDAC4, contributes to this degeneration; we now report that increased histone H3K27 trimethylation (H3K27me3) mediated by polycomb repressive complex 2 (PRC2) also plays an important role in the A-T phenotype. Enhancer of zeste homolog 2 (EZH2), a core catalytic component of PRC2, is identified as a new ATM kinase target, and its S734 phosphorylation reduces protein stability. Thus, PRC2 formation is elevated along with H3K27me3in ATM deficiency. ChIP-sequencing shows a significant increase in H3K27me3 ‘marks’ and a dramatic shift in their location. The change of H3K27me3 chromatin-binding pattern is directly related to cell cycle re-entry and cell death of ATM-deficient neurons. Lentiviral knockdown of EZH2 rescues Purkinje cell degeneration and behavioral abnormalities in Atm / mice, demonstrating that EZH2-mediated H3K27me3 is another key factor in A-T neurodegeneration.
Project description:LATS1/2 are canonical Hippo signaling pathway components. Our genome-wide screen indicated a synthetic viable effect of Hippo pathway inhibition in ATM-depleted human embryonic and neural progenitor cells. This experiment was designed in order to get mechanistic insights regarding the molecular effect of Hippo pathway inhibition on ATM-knockout cells. Such chemical inhibition could potentially be used as a means to impede Ataxia-Telangiectasia-related neurodegeneration. Experimental procedure: 2 clones of ATM-knockout h-pES10 cells were plated on 6 well plates with MEFs feeder layer. 1 d after plating, medium was replaced with standard medium (as control) or medium containing 10 µM of LATS1/2 inhibitor, TRULI (Lats-IN-1) for 24 h. Cells were then harvested, total RNA was extracted, libraries for RNA sequencing were generated and sequenced. Total reads were mapped to human GRCh38 reference genome, and to mouse GRCm38 using STAR package. XenofilteR package in R was used to filter out mouse-originated reads. Count tables and differential analysis were performed using EdgeR package in R.
Project description:Oxaliplatin(OXA) chemotherapy protocols are used in treatment of cancers like colorectal (CRC) and pancreatic cancer. OXA causes peripheral neuropathy which is considered treatment limiting factor. In recent studies, it shows that omeprazole(OME) has antioxidant effect and can inhibit organic cation transporter 2 (OCT2) in kidney. So OME can protect against peripheral neuropathy induced by OXA through oxidative stress . Also OME activates extracellular-signal-regulated kinase(ERK) / mitogen activated protein kinase ( MAPK) pathway, so improves demyelinating symptoms.
Project description:ATM kinase is a master regulator of the DNA damage response and loss of ATM leads to primary immunodeficiency and greatly increased risk for lymphoid malignancies. The FATC domain is conserved in Phosphatidylinositol-3-kinase-related protein kinases (PIKKs). Truncation mutation in the FATC domain (R3047X) selectively compromised reactive oxygen species-induced ATM activation in cell-free assays. Here we show that in mouse models, knock-in ATM-R3057X (AtmRX, corresponding to R3047X in human ATM) mutation severely compromises ATM protein stability, and causes T cell development and B cell immunoglobulin class switch recombination defects and infertility resembling ATM-null. The residual ATM R3057X protein retains minimal, yet functional measurable, DNA damage-induced checkpoint activation and significantly delays lymphomagenesis in AtmRX/RX mice compared to Atm-/-. Together, these results support a physiological role of the FATC domain in ATM protein stability and show that minimal ATM activity can prevent growth retardation and delay tumorigenesis without restoring lymphocyte development and fertility.
Project description:Epigenetic mechanism contributes to immune landscapes in cancer. Here we identify the SETDB1-TRIM28 complex as a critical suppressor of antitumor immunity. An epigenetic CRISPR-Cas9 screen of 1,218 chromatin regulators identified TRIM28 as a novel suppressor of PD-L1 expression. We revealed that expression of the SETDB1-TRIM28 complex negatively correlates with infiltration of effector CD8+ T cells. Inhibition of SETDB1-TRIM28 simultaneously upregulates PD-L1 and activates the cGAS-STING innate immune response to increase infiltration of CD8+ T cells. Mechanistically, SETDB1-TRIM28 inhibition leads to micronuclei formation in cytoplasm, a known activator of the cGAS-STING pathway. Thus, SETDB1-TRIM28 inhibition bridges the innate and adaptive immunity. Indeed, SETDB1 knockout enhances the antitumor effects of immune checkpoint blockade anti-PD-L1 in an ovarian cancer mouse model in a cGAS dependent manner. Our findings establish SETDB1-TRIM28 complex as a regulator of antitumor immunity and its loss activates cGAS-STING innate immunity to boost antitumor effects of immune checkpoint blockades.