Publications by authors named "Stéphane Lopes-Paciencia"

8 Publications

  • Page 1 of 1

A hydride transfer complex reprograms NAD metabolism and bypasses senescence.

Mol Cell 2021 Sep;81(18):3848-3865.e19

CRCHUM, 900 Saint-Denis St, Montréal, QC H2X 0A9, Canada; Département de Biochimie et Médecine Moléculaire, Université de Montréal, Montréal, QC H3C 3J7, Canada. Electronic address:

Metabolic rewiring and redox balance play pivotal roles in cancer. Cellular senescence is a barrier for tumorigenesis circumvented in cancer cells by poorly understood mechanisms. We report a multi-enzymatic complex that reprograms NAD metabolism by transferring reducing equivalents from NADH to NADP. This hydride transfer complex (HTC) is assembled by malate dehydrogenase 1, malic enzyme 1, and cytosolic pyruvate carboxylase. HTC is found in phase-separated bodies in the cytosol of cancer or hypoxic cells and can be assembled in vitro with recombinant proteins. HTC is repressed in senescent cells but induced by p53 inactivation. HTC enzymes are highly expressed in mouse and human prostate cancer models, and their inactivation triggers senescence. Exogenous expression of HTC is sufficient to bypass senescence, rescue cells from complex I inhibitors, and cooperate with oncogenic RAS to transform primary cells. Altogether, we provide evidence for a new multi-enzymatic complex that reprograms metabolism and overcomes cellular senescence.
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http://dx.doi.org/10.1016/j.molcel.2021.08.028DOI Listing
September 2021

Ribosomal protein RPL22/eL22 regulates the cell cycle by acting as an inhibitor of the CDK4-cyclin D complex.

Cell Cycle 2019 Mar - Apr;18(6-7):759-770. Epub 2019 Mar 28.

a Department of Biochemistry and Molecular Medicine , Université de Montréal , Montréal , Québec , Canada.

Senescence is a tumor suppressor program characterized by a stable growth arrest while maintaining cell viability. Senescence-associated ribogenesis defects (SARD) have been shown to regulate senescence through the ability of the ribosomal protein S14 (RPS14 or uS11) to bind and inhibit the cyclin-dependent kinase 4 (CDK4). Here we report another ribosomal protein that binds and inhibits CDK4 in senescent cells: L22 (RPL22 or eL22). Enforcing the expression of RPL22/eL22 is sufficient to induce an RB and p53-dependent cellular senescent phenotype in human fibroblasts. Mechanistically, RPL22/eL22 can interact with and inhibit CDK4-Cyclin D1 to decrease RB phosphorylation both in vitro and in cells. Briefly, we show that ribosome-free RPL22/eL22 causes a cell cycle arrest which could be relevant during situations of nucleolar stress such as cellular senescence or the response to cancer chemotherapy.
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http://dx.doi.org/10.1080/15384101.2019.1593708DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6464582PMC
April 2020

The senescence-associated secretory phenotype and its regulation.

Cytokine 2019 05 16;117:15-22. Epub 2019 Feb 16.

Department of Biochemistry and Molecular Medicine, Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, Québec H3C 3J7, Canada; CRCHUM, 900 Saint-Denis - Room R10.432, Montréal, QC H2X 0A9, Canada. Electronic address:

The senescence-associated secretory phenotype (SASP) defines the ability of senescent cells to express and secrete a variety of extracellular modulators that includes cytokines, chemokines, proteases, growth factors and bioactive lipids. The role of the SASP depends on the context. The SASP reinforces the senescent cell cycle arrest, stimulates the immune-mediated clearance of potentially tumorigenic cells, limits fibrosis and promotes wound healing and tissue regeneration. On the other hand, the SASP can mediate chronic inflammation and stimulate the growth and survival of tumor cells. The regulation of the SASP occurs at multiple levels including chromatin remodelling, activation of specific transcription factors such as C/EBP and NF-κB, control of mRNA translation and intracellular trafficking. Several SASP modulators have already been identified setting the stage for future research on their clinical applications.
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http://dx.doi.org/10.1016/j.cyto.2019.01.013DOI Listing
May 2019

Molecular tools that block maturation of the nuclear lamin A and decelerate cancer cell migration.

Bioorg Med Chem 2018 11 4;26(20):5547-5554. Epub 2018 Oct 4.

Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, QC H3A 0B8, Canada; Department of Biochemistry, McGill University, 3649 Promenade Sir William Osler, Montreal, QC H3G 0B1, Canada. Electronic address:

Lamin A contributes to the structure of nuclei in all mammalian cells and plays an important role in cell division and migration. Mature lamin A is derived from a farnesylated precursor protein, known as prelamin A, which undergoes post-translational cleavage catalyzed by the zinc metalloprotease STE24 (ZPMSTE24). Accumulation of farnesylated prelamin A in the nuclear envelope compromises cell division, impairs mitosis and induces an increased expression of inflammatory gene products. ZMPSTE24 has been proposed as a potential therapeutic target in oncology. A library of peptidomimetic compounds were synthesized and screened for their ability to induce accumulation of prelamin A in cancer cells and block cell migration in pancreatic ductal adenocarcinoma cells. The results of this study suggest that inhibitors of lamin A maturation may interfere with cell migration, the biological process required for cancer metastasis.
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http://dx.doi.org/10.1016/j.bmc.2018.10.001DOI Listing
November 2018

Senescence-associated ribosome biogenesis defects contributes to cell cycle arrest through the Rb pathway.

Nat Cell Biol 2018 07 25;20(7):789-799. Epub 2018 Jun 25.

Department of Biochemistry and Molecular Medicine, Université de Montréal, Montreal, Quebec, Canada.

Cellular senescence is a tumour suppressor programme characterized by a stable cell cycle arrest. Here we report that cellular senescence triggered by a variety of stimuli leads to diminished ribosome biogenesis and the accumulation of both rRNA precursors and ribosomal proteins. These defects were associated with reduced expression of several ribosome biogenesis factors, the knockdown of which was also sufficient to induce senescence. Genetic analysis revealed that Rb but not p53 was required for the senescence response to altered ribosome biogenesis. Mechanistically, the ribosomal protein S14 (RPS14 or uS11) accumulates in the soluble non-ribosomal fraction of senescent cells, where it binds and inhibits CDK4 (cyclin-dependent kinase 4). Overexpression of RPS14 is sufficient to inhibit Rb phosphorylation, inducing cell cycle arrest and senescence. Here we describe a mechanism for maintaining the senescent cell cycle arrest that may be relevant for cancer therapy, as well as biomarkers to identify senescent cells.
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http://dx.doi.org/10.1038/s41556-018-0127-yDOI Listing
July 2018

Quantitative SUMO proteomics reveals the modulation of several PML nuclear body associated proteins and an anti-senescence function of UBC9.

Sci Rep 2018 05 17;8(1):7754. Epub 2018 May 17.

Institute of Research in Immunology and Cancer, Université de Montréal, Montréal, QC H3C 3J7, Canada.

Several regulators of SUMOylation have been previously linked to senescence but most targets of this modification in senescent cells remain unidentified. Using a two-step purification of a modified SUMO3, we profiled the SUMO proteome of senescent cells in a site-specific manner. We identified 25 SUMO sites on 23 proteins that were significantly regulated during senescence. Of note, most of these proteins were PML nuclear body (PML-NB) associated, which correlates with the increased number and size of PML-NBs observed in senescent cells. Interestingly, the sole SUMO E2 enzyme, UBC9, was more SUMOylated during senescence on its Lys-49. Functional studies of a UBC9 mutant at Lys-49 showed a decreased association to PML-NBs and the loss of UBC9's ability to delay senescence. We thus propose both pro- and anti-senescence functions of protein SUMOylation.
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http://dx.doi.org/10.1038/s41598-018-25150-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5958138PMC
May 2018

is amplified in a large subset of human lung adenocarcinoma and is critical for epithelial lung cell identity and tumor metastasis.

FASEB J 2017 11 28;31(11):5012-5018. Epub 2017 Jul 28.

Laboratory of Molecular Genetics of Stem Cells, Université de Montréal, Montreal, Québec, Canada;

The ubiquitin-associated protein 2-like () gene remains poorly studied in human and mouse development. UBAP2L interacts with the Polycomb group protein B lymphoma Mo-MLV insertion region 1 homolog (BMI1) and determines the activity of mouse hematopoietic stem cells Here we show that loss of leads to disorganized respiratory epithelium of mutant neonates, which die of respiratory failure. We also show that overexpression leads to epithelial-mesenchymal transition-like phenotype in a non-small cell lung carcinoma (NSCLC) cell line. is amplified in 15% of human primary lung adenocarcinoma specimens. Such patients express higher levels of and show a reduction in survival when compared with those who do not have this gene amplification. Supporting a possible role for in lung tumor progression, NSCLC cells engineered to express low levels of this gene produce much smaller tumors than wild-type control cells. Together, these results suggest that contributes to epithelial lung cell identity in mice and that it plays an important role in human lung adenocarcinoma.-Aucagne, R., Girard, S., Mayotte, N., Lehnertz, B., Lopes-Paciencia, S., Gendron, P., Boucher, G., Chagraoui, J., Sauvageau, G. is amplified in a large subset of human lung adenocarcinoma and is critical for epithelial lung cell identity and tumor metastasis.
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http://dx.doi.org/10.1096/fj.201601219RRRDOI Listing
November 2017

Permanent farnesylation of lamin A mutants linked to progeria impairs its phosphorylation at serine 22 during interphase.

Aging (Albany NY) 2016 Feb;8(2):366-81

Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Québec, H3C 3J7, Canada.

Mutants of lamin A cause diseases including the Hutchinson-Gilford progeria syndrome (HGPS) characterized by premature aging. Lamin A undergoes a series of processing reactions, including farnesylation and proteolytic cleavage of the farnesylated C-terminal domain. The role of cleavage is unknown but mutations that affect this reaction lead to progeria. Here we show that interphase serine 22 phosphorylation of endogenous mutant lamin A (progerin) is defective in cells from HGPS patients. This defect can be mimicked by expressing progerin in human cells and prevented by inhibition of farnesylation. Furthermore, serine 22 phosphorylation of non-farnesylated progerin was enhanced by a mutation that disrupts lamin A head to tail interactions. The phosphorylation of lamin A or non-farnesylated progerin was associated to the formation of spherical intranuclear lamin A droplets that accumulate protein kinases of the CDK family capable of phosphorylating lamin A at serine 22. CDK inhibitors compromised the turnover of progerin, accelerated senescence of HGPS cells and reversed the effects of FTI on progerin levels. We discuss a model of progeria where faulty serine 22 phosphorylation compromises phase separation of lamin A polymers, leading to accumulation of functionally impaired lamin A structures.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4789588PMC
http://dx.doi.org/10.18632/aging.100903DOI Listing
February 2016
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