Carboxy-Methylation of PP2Ac Integrates Methionine Availability with Cancer Cell Proliferation
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PROVIDER: PRJNA1285445 | ENA |
REPOSITORIES: ENA
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Project description:Cancer cells exhibit a well-documented, yet poorly understood, dependence on exogenous methionine, despite retaining the capacity to convert homocysteine to methionine. In contrast, non-tumorigenic cells can proliferate when methionine is replaced by homocysteine. To investigate the mechanistic basis of this methionine dependence, we examined how methionine metabolism impacts cancer cell proliferation. We identified carboxy-methylation of the catalytic subunit of Protein Phosphatase 2A (PP2A) as a critical node linking methionine availability to proliferation. PP2A methylation was found to be highly sensitive to intracellular S-adenosylmethionine (SAM) levels, with reduced methylation correlating with impaired proliferation under methionine restriction. Overexpression of Protein Phosphatase Methylesterase-1 (PME-1), which demethylates PP2A, or expression of a Leu309-deleted PP2A mutant that mimics the demethylated form, was sufficient to reduce proliferation even in methionine-independent cells. These findings support a model in which methionine limitation lowers SAM availability, thereby decreasing PP2A methylation and impairing cell proliferation. Our study reveals a mechanistic link between methionine metabolism and cell proliferation and suggests that PP2A methylation plays a key role in the unique methionine dependence of cancer cells.
2025-07-03 | GSE301557 | GEO
Project description:Protein phosphatase 2A (PP2A) is one of the most common serine/threonine phosphatases in mammalian cells and primarily functions to regulate cell signaling, glycolipid metabolism, and apoptosis. Its PP2A catalytic subunit (PP2Ac) plays an important role in its function. Nonetheless, at present, there are only a few reports on the regulatory role of PP2Ac in pancreatic β-cells under lipotoxicity. Mouse pancreatic insulinoma (MIN6) cells were transfected by lentiviruses to generate PP2Ac knockdown cells and incubated with palmitate (PA) to establish the lipotoxicity model. Serine/Threonine Phosphatase Assay System kit, Cell Counting Kit-8 (CCK-8), flow cytometry, enzyme-linked immunosorbent assay (ELISA), Western Blotting (WB) and other techniques were used to measure PP2A activity, cell viability, apoptosis, oxidative stress, and insulin secretion. An animal model of lipotoxicity with knockdown of PP2Ac was established by a high-fat diet (HFD) after using adeno-associated viruses (AAV) to interfere with PP2Ac expression in mouse pancreatic tissues. Serine/Threonine Phosphatase Assay System kit, ELISA, pancreatic tissue immunofluorescence and other techniques were used to measure PP2A activity in pancreatic tissue, serum insulin level and the proliferation of mouse pancreatic β-cells. We found that PP2Ac knockdown inhibited lipotoxicity-induced PP2A hyperactivation, increased the resistance of pancreatic β-cells to lipotoxicity, decreased PA-induced apoptosis in MIN6 cells, protected the function of both the endoplasmic reticulum (ER) and mitochondria, and improved insulin secretion. By mRNA sequencing and Western blotting analysis, we hypothesized that the protective effects of PP2Ac knockdown in MIN6 cells may be mediated by the MAPK pathway. Moreover, the results obtained from animal experiments suggest that the specific knockdown of pancreatic PP2Ac could effectively attenuate HFD-induced insulin resistance and reduce the compensatory proliferation of pancreatic β-cells in mice. The present study revealed the effects and mechanisms of interfering with PP2Ac gene expression on pancreatic β-cells in vivo and in vitro, which might provide insights for the treatment of type 2 diabetes in the clinic.
2023-09-13 | GSE242538 | GEO
Project description:Histone modifications are integral to epigenetics through their influence on gene expression and cellular status. While it's established that metabolism, including methionine metabolism, can impact histone methylation, the direct influence of methionine availability on crucial histone marks that determine the epigenomic process remains poorly understood. In this study, we demonstrate that methionine, through its metabolic product, S-adenosylmethionine (SAM), dynamically regulates H3K36me3, a cancer-associated histone modification known to influence cellular status, and myogenic differentiation of mouse myoblast cells. We further demonstrate that the methionine-dependent effects on differentiation are mediated in part through the histone methyltransferase SETD2, which senses methionine levels. Additionally, methionine restriction leads to preferential decreases in H3K36me3 abundance and genome accessibility of genes involved in myogenic differentiation. Importantly, the effects of methionine restriction on differentiation and chromatin accessibility can be phenocopied by the deletion of Setd2. Collectively, this study demonstrates that methionine metabolism through its ability to be sensed by chromatin modifying enzymes can have a direct role in influencing cell fate determination.
2023-11-30 | GSE248198 | GEO
Project description:Histone modifications are integral to epigenetics through their influence on gene expression and cellular status. While it's established that metabolism, including methionine metabolism, can impact histone methylation, the direct influence of methionine availability on crucial histone marks that determine the epigenomic process remains poorly understood. In this study, we demonstrate that methionine, through its metabolic product, S-adenosylmethionine (SAM), dynamically regulates H3K36me3, a cancer-associated histone modification known to influence cellular status, and myogenic differentiation of mouse myoblast cells. We further demonstrate that the methionine-dependent effects on differentiation are mediated in part through the histone methyltransferase SETD2, which senses methionine levels. Additionally, methionine restriction leads to preferential decreases in H3K36me3 abundance and genome accessibility of genes involved in myogenic differentiation. Importantly, the effects of methionine restriction on differentiation and chromatin accessibility can be phenocopied by the deletion of Setd2. Collectively, this study demonstrates that methionine metabolism through its ability to be sensed by chromatin modifying enzymes can have a direct role in influencing cell fate determination.
2023-11-30 | GSE248197 | GEO
Project description:A transgenic mouse was generated using a CD2-driven transgene containing the cDNA of Ppp2ca to achieve over-expression of PP2Ac in T cells. Naïve CD4 T cells were isolated and lysed at times 0, 6, and 24 hours after stimulation with anti-CD3 and anti-CD28 Naïve CD4 T cells from wild type mice were compared with naïve CD4 T cells from PP2Ac transgenic mice
2013-08-02 | E-GEOD-49466 | biostudies-arrayexpress
Project description:A transgenic mouse was generated using a CD2-driven transgene containing the cDNA of Ppp2ca to achieve over-expression of PP2Ac in T cells. Naïve CD4 T cells were isolated and lysed at times 0, 6, and 24 hours after stimulation with anti-CD3 and anti-CD28
2013-08-02 | GSE49466 | GEO
Project description:Methionine availability influences essential H3K36me3 dynamics during cell differentiation
| PRJNA1042641 | ENA
Project description:Osteolytic lesions with suppression of osteoblastic (OB) differentiation are hallmarks of multiple myeloma (MM). Most recently, Gln availability has been found to be essential to sustain bone mass formation in murine models. On the other hand, MM cells are Gln-addicted and consume huge amounts of the amino acid, leading to a partial Gln depletion in the bone marrow (BM) plasma. We hypothesize that MM-dependent Gln depletion contributes to the defective OB differentiation characteristic of MM. Conversely, GLS (both KGA and GAC isoforms) and SLC38A2, the gene for the concentrative Gln transporter SNAT2, were induced. Consistent with this conclusion, the activity of SNAT2 was absent in undifferentiated hMSCs but well detectable after 14 days of OB differentiation, when total Gln uptake was also increased. Under the same conditions, OB differentiation markers (RUNX2, COL1A1, ALPL expression and ALPL activity or staining) were significantly induced but their expression was blunted by incubation in low-Gln (0.4 mM) medium or in the presence of the SNAT2 inhibitor MeAIB. The incubation in Gln-free D-MEM suppressed the induction of GLS and SLC38A2 along with OB differentiation, which was restored by the supplementation of Non-Essential Amino Acids (NEAA). Among NEAA, only asparagine (Asn) was able to rescue OB differentiation in the absence of Gln. The determination of intracellular amino acids with MS indicated that OB differentiation was associated with the increase of cell Asn, without significant changes of Gln, glutamate (Glu) or aspartate (Asp). Asparagine Synthetase (ASNS), the Gln-dependent enzyme that accounts for Asn synthesis, was also found induced during OB differentiation of hMSCs. Gene Expression Profiles of primary BM hMSCs and OBs from bone biopsies of both healthy donors and MM patients indicated that GLS, ASNS, and SLC38A2 are more expressed in OBs, while the expression of GLUL, the gene for GS, is higher in undifferentiated hMSCs from healthy donors. Overall, these results indicate that (1) OB differentiation of hMSCs is Gln-dependent; (2) the partial Gln depletion, imposed by Gln-addicted MM cells in the BM microenvironment, contributes to the impairment of osteoblastic differentiation of hMSCs; (3) hindrance of differentiation may depend on the limited availability of intracellular Asn derived from Gln-dependent ASNS. These results support the evidence that Gln addiction of MM cells affects bone microenvironment leading to the inhibition of OB differentiation and, consequently, to the development of MM bone disease.
2020-12-01 | GSE147791 | GEO
Project description:BSA pooling experiment for methionine content in a segrating diploid potato population (CxE). RNA of constrasting individuals for methionine content are pooled together based on their tuber methionine content and marker association with either or both of the identified QTLs for methionine content
2009-11-20 | E-MEXP-2441 | biostudies-arrayexpress
Project description:Dietary methionine restriction is associated with a reduction in tumor growth in preclinical studies and an increase in lifespan in animal models. The mechanism by which methionine restriction inhibits tumor growth while sparing normal cells is incompletely understood, except for the observation that normal cells can utilize methionine or homocysteine interchangeably (methionine independence) while most cancer cells are strictly dependent on methionine availability. Here, we compared a typical methionine dependent and a rare methionine independent melanoma cell line. We show that replacing methionine, a methyl donor, with homocysteine generally induced hypomethylation in gene promoters. This decrease was similar in methionine dependent versus methionine independent cells. There was only a low level of pathway enrichment, suggesting that the hypomethylation is generic rather than gene specific. Whole proteome and transcriptome were also analyzed. This analysis revealed that contrarily to the effect on methylation, the replacement of methionine with homocysteine had a much greater effect on the transcriptome and proteome of methionine dependent cells than methionine independent cells. Interestingly, the methionine adenosyltransferase 2A (MAT2A), responsible for the synthesis of s-adenosylmethionine from methionine, was equally strongly upregulated in both cell lines. This suggests that the absence of methionine is equally detected but trigger different outcomesin methionine dependent versus independent cells. Our analysis reveals the importance of cell cycle control, DNA damage repair, translation, nutrient sensing, oxidative stress and tight junctions in the cellular response to methionine stress in melanoma.
2023-05-03 | GSE225944 | GEO