MTORC1-Driven DDA1 Phosphorylation Promotes DNA Repair and Glioblastoma Progression
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PROVIDER: PRJNA1293952 | ENA |
REPOSITORIES: ENA
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Project description:DDA1 is a protein involved in protein degradation, cell cycle regulation, and DNA damage repair. Interestingly, recent studies have revealed its differential expression across various tumor types. However, how DDA1 functions as a tumorogenic factor remains to be elucidated. Through studies in multiple glioblastoma cell models, we identified a physical association between cytoplasmic DDA1 and Raptor, a key component of lysosome-associated mTORC1. We report that amino acid stimulation triggers phosphorylation of DDA1 at serine 33, promoting its nuclear translocation and involvement in DNA damage repair. Integrated genomic and transcriptomic analyses revealed that the mTORC1-DDA1S33-DNA repair axis regulates the expression of a subset of metabolic genes, including ENO2, a glycolytic enzyme; CA12, which contributes to intracellular and extracellular pH homeostasis; and NMRK1, a key enzyme in nicotinamide riboside metabolism. Notably, DDA1 deficiency markedly impaired glioblastoma growth and triggered a compensatory upregulation of metabolic activity to sustain tumor cell survival. These metabolic genes likely supply essential nutrients required for effective DNA repair. Our findings establish DDA1 as a previously unrecognized phosphorylation target downstream of mTORC1, serving as a critical mediator of mTORC1-driven DNA damage response and a key regulator of glioblastoma progression, thereby expanding our understanding of gliomagenesis.
2025-07-29 | GSE303079 | GEO
Project description:Lysosomes are central platforms for not only the degradation of macromolecules but also the integration of multiple signaling pathways. However, whether and how lysosomes mediate the mitochondrial stress response (MSR) remain largely unknown. Here, we demonstrate that lysosomal acidification via the vacuolar H+-ATPase (v-ATPase) is essential for the transcriptional activation of the mitochondrial unfolded protein response (UPRmt). Mitochondrial stress stimulates v-ATPase-mediated lysosomal activation of the mechanistic target of rapamycin complex 1 (mTORC1), which then directly phosphorylates the MSR transcription factor, activating transcription factor 4 (ATF4). Disruption of mTORC1-dependent ATF4 phosphorylation blocks the UPRmt, but not other similar stress responses, such as the UPRER. Finally, ATF4 phosphorylation downstream of the v-ATPase/mTORC1 signaling is indispensable for sustaining mitochondrial redox homeostasis and protecting cells from reactive oxygen species (ROS)-associated cell death upon mitochondrial stress. Thus, v-ATPase/mTORC1-mediated ATF4 phosphorylation via lysosomes links mitochondrial stress to UPRmt activation and mitochondrial function resilience.
2023-06-19 | GSE179510 | GEO
Project description:PDX1 is known as the insulin transcription factor that regulates insulin expression in pancreatic β-cells in response to circulating glucose levels. Our previous study showed PDX1 also acts as a downstream effector that mediates β-cell mTORC1 signaling in the control of whole-body glucose homeostasis in response to stimulation by amino acids (AAs). Here we report that PDX1 has a broad role in AA-mTORC1-regulated transcriptome in β-cells, especially in processes related to β-cell proliferation and function. Mechanistically, mTORC1 phosphorylates PDX1 at S61 in an AA-dependent and rapamycin-sensitive manner. S61 phosphorylation promotes PDX1 protein levels and transcriptional activity. Interestingly, S61 is located within the transactivation domain targeted by monogenic diabetes mutations, which interfere with S61 phosphorylation and PDX1's transcriptional activity. To help understand the role of S61 phosphorylation in vivo, we generated S61A and S61E genomic mutations in mice, mimicking the unphosphorylated and phosphorylated states, respectively. Our results indicate that S61 phosphorylation positively regulates insulin expression and β-cell proliferation, promoting Western diet-induced hyperinsulinemia, obesity, and liver steatosis. These findings reveal the mechanism and roles of AA-mTORC1-PDX1 signaling in the control of pancreatic β-cell proliferation and function under physiological and pathological conditions.
2025-12-01 | GSE278790 | GEO
Project description:PDX1 is known as the insulin transcription factor that regulates insulin expression in pancreatic β-cells in response to circulating glucose levels. Our previous study showed PDX1 also acts as a downstream effector that mediates β-cell mTORC1 signaling in the control of whole-body glucose homeostasis in response to stimulation by amino acids (AAs). Here we report that PDX1 has a broad role in AA-mTORC1-regulated transcriptome in β-cells, especially in processes related to β-cell proliferation and function. Mechanistically, mTORC1 phosphorylates PDX1 at S61 in an AA-dependent and rapamycin-sensitive manner. S61 phosphorylation promotes PDX1 protein levels and transcriptional activity. Interestingly, S61 is located within the transactivation domain targeted by monogenic diabetes mutations, which interfere with S61 phosphorylation and PDX1's transcriptional activity. To help understand the role of S61 phosphorylation in vivo, we generated S61A and S61E genomic mutations in mice, mimicking the unphosphorylated and phosphorylated states, respectively. Our results indicate that S61 phosphorylation positively regulates insulin expression and β-cell proliferation, promoting Western diet-induced hyperinsulinemia, obesity, and liver steatosis. These findings reveal the mechanism and roles of AA-mTORC1-PDX1 signaling in the control of pancreatic β-cell proliferation and function under physiological and pathological conditions.
2025-12-01 | GSE278789 | GEO
Project description:Lysosomes mediate the mitochondrial UPR via mTORC1-dependent ATF4 phosphorylation
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Project description:The protein Lgl has key roles in the regulation of cell polarity. We have shown that Lgl is inactivated by hyperphosphorylation in glioblastoma as a consequence of PTEN loss and aberrant activation of the PI 3-kinase pathway; this contributes to glioblastoma pathogenesis both by promoting invasion and repressing glioblastoma cell differentiation. Lgl is phosphorylated by atypical protein kinase C in a complex with Par6 and either activated Cdc42 or activated Rac. Here we have investigated the role of specific Rac guanine nucleotide exchange factors in Lgl hyperphosphorylation in glioblastoma. We used CRISPR/Cas9 to knockout PREX1, a PI 3-kinase pathway-responsive Rac guanine nucleotide exchange factor that is overexpressed in glioblastoma. Knockout of PREX1 in patient-derived glioblastoma cells resulted in a reduction in Lgl phosphorylation and this could be reversed by re-expressing PREX1. PREX1 knockout cells showed reduced motility and altered phenotype suggestive of partial neuronal differentiation; consistent with this, RNA-seq analyses of these cells identified sets of PREX1-regulated genes with roles in promoting cell motility and repressing neuronal differentiation. Knockout of PREX1 in glioblastoma cells derived from a second patient did not affect Lgl phosphorylation. These cells overexpressed a short isoform of the Rac guanine nucleotide exchange factor TIAM1; knockdown of TIAM1 in PREX1-knockout cells from this patient reduced Lgl phosphorylation. These data show that PREX1 links aberrant PI 3-kinase to Lgl phosphorylation in glioblastoma, but that TIAM1 can also promote Lgl phosphorylation in a subset of patients. While this shows redundant mechanisms for Lgl phosphorylation, PREX1 appears to have a non-redundant role in glioblastoma cell motility, as this was impaired in PREX1 knockout cells from both patients.
2021-08-23 | GSE162783 | GEO
Project description:Generate scRNA-Seq profiles for PDGF-driven glioblastoma mouse model.
2018-02-23 | GSE95157 | GEO
Project description:Here we describe a bead-based method capable of profiling tyrosine kinase phosphorylations in a multiplexed, high-throughput and low-cost manner. This approach allows for the discovery of tyrosine kinase-activating events, even when the DNA sequence is wild-type. In an effort to pilot the establishment of a tyrosine kinase activation catalog, we profiled tyrosine phosphorylation levels of 62 tyrosine kinases in 130 human cancer lines, and followed-up on the frequent SRC phosphorylation in glioblastoma. Keywords: quantitative measurements of tyrosine phosphorylation levels on tyrosine kinases Total protein lysates were collected from 130 cancer cell lines. Tyrosine phosphorylation levels on 62 tyrosine kinases were measured with the bead assay.
2010-06-24 | E-GEOD-13808 | biostudies-arrayexpress
Project description:Hereditary spastic paraplegia type 21 (SPG21) is an inherited neurological disorder caused by mutations in the SPG21 gene, which encodes a protein named SPG21 or maspardin. Herein, we report that SPG21 localizes to endolysosomes through interaction with the GTP-bound form of RAB7A. Disease-associated SPG21 variants reduce expression of SPG21 and disrupt its endolysosomal localization in both non-neuronal cells and neurons. Consistent with this localization, functional dependency analysis links SPG21 to endolysosomal and mTORC1 signaling pathways. Biochemical studies reveal that SPG21 depletion does not affect phosphorylation of canonical mTORC1 substrates such as ULK1, S6K1, 4E-BP1, but reduces phosphorylation of the non-canonical mTORC1 substrate TFEB. This enhances nuclear localization of TFEB and upregulation of TFEB-target genes. We conclude that SPG21 acts as a RAB7A effector that promotes non-canonical mTORC1-catalyzed phosphorylation of TFEB, thereby suppressing its nuclear localization and transcriptional activity. These findings link SPG21 dysfunction to altered endolysosomal signaling, offering new insights into SPG21 pathogenesis.
2025-11-18 | GSE304705 | GEO