Dataset Information

Sizek2023 - Mitochondrial Dysfunction-Associated Senescence (MiDAS) with cell cycle and apoptosis

ABSTRACT: This 133-node Boolean regulatory network model reproduces mitochondrial dynamics during cell cycle progression (hyper-fusion at the G1/S boundary, fission in mitosis), apoptosis (fission and dysfunction) and glucose starvation (reversible hyper-fusion), as well as MiDAS in response to SIRT3 knockdown or oxidative stress and the protective role of NAD+ or external pyruvate. These features are in addition to the cell cycle-related phenotypes reproduced by the Sizek et al model that served as our starting point. Testable predictions (new): a) In cell lines with low basal p21 expression known to pre-commit to the next division in early mitosis of their current cycle, a subset of cells respond to glucose withdrawal by arresting with 4N DNA content but losing their internal G2 state (i.e. Cyclin A/B expression), and undergo endo-reduplication upon glucose re-exposure. b) In a subset of glucose-starved cells that pass the G2/M checkpoint with hyperfused mitochondria, mitotic fragmentation can be sufficiently delayed to cause spindle assembly defects and mitotic catastrophe. c) Quiescent cells are less susceptible to ROS-induced MiDAS due to FoxO-mediated PINK1 expression, which blocks MFN1/2 from inducing hyperfusion. d) Boosting NAD+ levels in MiDAS cells that have not yet established deep senescence (2-3 days post induction) can reverse their fate.

SUBMITTER: Erzsébet Ravasz Regan

PROVIDER: MODEL2312140001 | BioModels | 2024-08-26

REPOSITORIES: BioModels

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Publications

Unlocking mitochondrial dysfunction-associated senescence (MiDAS) with NAD<sup>+</sup> - A Boolean model of mitochondrial dynamics and cell cycle control.

Sizek Herbert H Deritei Dávid D Fleig Katherine K Harris Marlayna M Regan Peter L PL Glass Kimberly K Regan Erzsébet Ravasz ER

Translational oncology 20240819

The steady accumulation of senescent cells with aging creates tissue environments that aid cancer evolution. Aging cell states are highly heterogeneous. 'Deep senescent' cells rely on healthy mitochondria to fuel a strong proinflammatory secretome, including cytokines, growth and transforming signals. Yet, the physiological triggers of senescence such as reactive oxygen species (ROS) can also trigger mitochondrial dysfunction, and sufficient energy deficit to alter their secretome and cause chro ...[more]

PMID: 39163758

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Project description:Mitochondria are highly dynamic organelles undergoing fusion, fission and degradation. Although mitochondria are known to be essential for cellular metabolism, it is not fully understood how mitochondrial dynamics affect cellular metabolism. We previously identified a mouse gene, transmembrane protein 135 (TMEM135) that plays a role in the regulation of mitochondrial dynamics. Mice with mutant Tmem135 (Tmem135FUN025/FUN025) show accelerated aging phenotypes and age-related pathologies in the retina including the retinal pigment epithelium (RPE). We also generated a transgenic mouse line globally overexpressing the Tmem135 gene (Tmem135 TG). In several tissues and cells that we studied such as the retina, heart and fibroblast cells, we observed that the Tmem135 mutation causes elongated mitochondria, while over-expression of Tmem135 results in fragmented mitochondria. These unique mouse models allow us to test how abnormal mitochondrial dynamics affect metabolic signatures of tissues and cells. In this study, we identified metabolic changes in primary RPE cell cultures as well as tissues isolated from Tmem135FUN025/FUN025 mice (fusion > fission) and Tmem135 TG mice (fusion < fission) using nuclear magnetic resonance (NMR) spectroscopy. Metabolomics analysis revealed a tissue-dependent response to alterations to Tmem135 whereby, significant metabolic changes were observed in heart in both mutant and TG mice as compared to WT while negligible effects were observed in cerebellum and hippocampus. We also observed changes in Tmem135FUN025/FUN025 and Tmem135 TG RPE cells associated with osmosis, glucose metabolism and phospholipid metabolism. Significant depletion of NAD+ was detected in both Tmem135FUN025/FUN025 and Tmem135 TG RPE cells, indicating that imbalance in mitochondrial dynamics to both directions lowers the cellular NAD+ level. Thus, we have identified metabolomic changes associated with imbalanced mitochondrial dynamics in heart tissue and RPE cells which can likely lead to functional abnormalities.

Project description:To achieve faithful replication of the genome once in each cell cycle, re-initiation of S-phase is prevented in G2 and origins are restricted from re-firing within S-phase. We have investigated the block to re-replication during G2 in fission yeast. The DNA synthesis that occurs when G2/M cyclin dependent kinase (CDK) activity is depleted has been assumed to be repeated rounds of S-phase without mitosis but this has not been demonstrated to be the case. In a normal mitotic S-phase, the genome is uniformly replicated with no areas amplified relative to other regions, so there is an equal copy number of each portion of the genome. To determine whether equal rounds of replication or local amplification occurred in the cdc13 s/o strain we assayed genomic DNA from cells which had increased their DNA content to 16C-32C. Using microarrays, we measured the relative DNA content across the genome, using DNA from control G1-arrested cells as a reference. This experiment revealed that replication was essentially equal across the genome, with no region becoming significantly amplified to a higher copy number than any other. Since the genome was found to be essentially evenly replicated as would be expected if each round of replication corresponded to a normal S-phase, we investigated whether this was the result of a normal replication program at the level of origin firing. We asked whether S-phase origins are used to reduplicate the genome, and whether origins are used with the same efficiency as in wild type cells. We identified the origins utilized in the first endoreduplication cycle of cdc13 s/o using microarray analyses of cells treated with 11 mM HU. Samples were taken at 5 hours when most cells of the culture not treated with HU had undergone a doubling in DNA content. A total of 799 origins were identified, a number roughly similar to the 904 identified in a normal S-phase. We show here that on G2/M CDK depletion in G2, repeated S-phases are induced. Mostly normal mitotic S-phase origins were utilized although at different efficiencies, and replication was essentially equal across the genome. We conclude that CDK inhibits re-initiation of S-phase during G2, and if G2/M CDK is depleted replication results from induction of a largely normal S-phase program with only small differences in origin usage and efficiency.

Dataset Information

Sizek2023 - Mitochondrial Dysfunction-Associated Senescence (MiDAS) with cell cycle and apoptosis

Publications

Unlocking mitochondrial dysfunction-associated senescence (MiDAS) with NAD<sup>+</sup> - A Boolean model of mitochondrial dynamics and cell cycle control.

Similar Datasets

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