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Palmer N, Kaldis P. Less-well known functions of cyclin/CDK complexes. Semin Cell Dev Biol 2020; 107:54-62. [PMID: 32386818 DOI: 10.1016/j.semcdb.2020.04.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 04/07/2020] [Accepted: 04/08/2020] [Indexed: 12/31/2022]
Abstract
Cyclin-dependent kinases (CDKs) are activated by cyclins, which play important roles in dictating the actions of CDK/cyclin complexes. Cyclin binding influences the substrate specificity of these complexes in addition to their susceptibility to inhibition or degradation. CDK/cyclin complexes are best known to promote cell cycle progression in the mitotic cell cycle but are also crucial for important cellular processes not strictly associated with cellular division. This chapter primarily explores the understudied topic of CDK/cyclin complex functionality during the DNA damage response. We detail how CDK/cyclin complexes perform dual roles both as targets of DNA damage checkpoint signaling as well as effectors of DNA repair. Additionally, we discuss the potential CDK-independent roles of cyclins in these processes and the impact of such roles in human diseases such as cancer. Our goal is to place the spotlight on these important functions of cyclins either acting as independent entities or within CDK/cyclin complexes which have attracted less attention in the past. We consider that this will be important for a more complete understanding of the intricate functions of cell cycle proteins in the DNA damage response.
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Affiliation(s)
- Nathan Palmer
- Institute of Molecular and Cell Biology (IMCB), A⁎STAR (Agency for Science, Technology and Research), 61 Biopolis Drive, Proteos, Singapore, 138673, Republic of Singapore; National University of Singapore (NUS), Department of Biochemistry, Singapore, 117597, Republic of Singapore
| | - Philipp Kaldis
- Institute of Molecular and Cell Biology (IMCB), A⁎STAR (Agency for Science, Technology and Research), 61 Biopolis Drive, Proteos, Singapore, 138673, Republic of Singapore; National University of Singapore (NUS), Department of Biochemistry, Singapore, 117597, Republic of Singapore; Department of Clinical Sciences, Lund University, Clinical Research Centre (CRC), Box 50332, SE-202 13, Malmö, Sweden.
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The Involvement of PPARs in the Peculiar Energetic Metabolism of Tumor Cells. Int J Mol Sci 2018; 19:ijms19071907. [PMID: 29966227 PMCID: PMC6073339 DOI: 10.3390/ijms19071907] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 06/10/2018] [Accepted: 06/24/2018] [Indexed: 12/13/2022] Open
Abstract
Energy homeostasis is crucial for cell fate, since all cellular activities are strongly dependent on the balance between catabolic and anabolic pathways. In particular, the modulation of metabolic and energetic pathways in cancer cells has been discussed in some reports, but subsequently has been neglected for a long time. Meanwhile, over the past 20 years, a recovery of the study regarding cancer metabolism has led to an increasing consideration of metabolic alterations in tumors. Cancer cells must adapt their metabolism to meet their energetic and biosynthetic demands, which are associated with the rapid growth of the primary tumor and colonization of distinct metastatic sites. Cancer cells are largely dependent on aerobic glycolysis for their energy production, but are also associated with increased fatty acid synthesis and increased rates of glutamine consumption. In fact, emerging evidence has shown that therapeutic resistance to cancer treatment may arise from the deregulation of glucose metabolism, fatty acid synthesis, and glutamine consumption. Cancer cells exhibit a series of metabolic alterations induced by mutations that lead to a gain-of-function of oncogenes, and a loss-of-function of tumor suppressor genes, including increased glucose consumption, reduced mitochondrial respiration, an increase of reactive oxygen species, and cell death resistance; all of these are responsible for cancer progression. Cholesterol metabolism is also altered in cancer cells and supports uncontrolled cell growth. In this context, we discuss the roles of peroxisome proliferator-activated receptors (PPARs), which are master regulators of cellular energetic metabolism in the deregulation of the energetic homeostasis, which is observed in cancer. We highlight the different roles of PPAR isotypes and the differential control of their transcription in various cancer cells.
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Kamarajugadda S, Becker JR, Hanse EA, Mashek DG, Mashek MT, Hendrickson AM, Mullany LK, Albrecht JH. Cyclin D1 represses peroxisome proliferator-activated receptor alpha and inhibits fatty acid oxidation. Oncotarget 2018; 7:47674-47686. [PMID: 27351284 PMCID: PMC5216970 DOI: 10.18632/oncotarget.10274] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 06/04/2016] [Indexed: 01/27/2023] Open
Abstract
Cyclin D1 is a cell cycle protein that promotes proliferation by mediating progression through key checkpoints in G1 phase. It is also a proto-oncogene that is commonly overexpressed in human cancers. In addition to its canonical role in controlling cell cycle progression, cyclin D1 affects other aspects of cell physiology, in part through transcriptional regulation. In this study, we find that cyclin D1 inhibits the activity of a key metabolic transcription factor, peroxisome proliferator-activated receptor α (PPARα), a member of nuclear receptor family that induces fatty acid oxidation and may play an anti-neoplastic role. In primary hepatocytes, cyclin D1 inhibits PPARα transcriptional activity and target gene expression in a cdk4-independent manner. In liver and breast cancer cells, knockdown of cyclin D1 leads to increased PPARα transcriptional activity, expression of PPARα target genes, and fatty acid oxidation. Similarly, cyclin D1 depletion enhances binding of PPARα to target sequences by chromatin immunoprecipitation. In proliferating hepatocytes and regenerating liver in vivo, induction of endogenous cyclin D1 is associated with diminished PPARα activity. Cyclin D1 expression is both necessary and sufficient for growth factor-mediated repression of fatty acid oxidation in proliferating hepatocytes. These studies indicate that in addition to playing a pivotal role in cell cycle progression, cyclin D1 represses PPARα activity and inhibits fatty acid oxidation. Our findings establish a new link between cyclin D1 and metabolism in both tumor cells and physiologic hepatocyte proliferation.
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Affiliation(s)
- Sushama Kamarajugadda
- Gastroenterology Division, Minneapolis VA Health Care System, Minneapolis, MN 55417, USA
| | - Jennifer R Becker
- Minneapolis Medical Research Foundation, Minneapolis, MN, 55404, USA
| | - Eric A Hanse
- Minneapolis Medical Research Foundation, Minneapolis, MN, 55404, USA
| | - Douglas G Mashek
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Mara T Mashek
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | | | - Lisa K Mullany
- Minneapolis Medical Research Foundation, Minneapolis, MN, 55404, USA
| | - Jeffrey H Albrecht
- Gastroenterology Division, Minneapolis VA Health Care System, Minneapolis, MN 55417, USA
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Bendris N, Lemmers B, Blanchard JM. Cell cycle, cytoskeleton dynamics and beyond: the many functions of cyclins and CDK inhibitors. Cell Cycle 2016; 14:1786-98. [PMID: 25789852 DOI: 10.1080/15384101.2014.998085] [Citation(s) in RCA: 123] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
While targeting experiments carried out on the genes encoding many cell cycle regulators have challenged our views of cell cycle control, they also suggest that redundancy might not be the only explanation for the observed perplexing phenotypes. Indeed, several observations hint at functions of cyclins and CDK inhibitors that cannot be accounted for by their sole role as kinase regulators. They are found involved in many cellular transactions, depending or not on CDKs that are not directly linked to cell cycle control, but participating to general mechanisms such as transcription, DNA repair or cytoskeleton dynamics. In this review we discuss the roles that these alternative functions might have in cancer cell proliferation and migration that sometime even challenge their definition as proliferation markers.
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Affiliation(s)
- Nawal Bendris
- a Institut de Génétique Moléculaire de Montpellier; CNRS; Montpellier; France; Université Montpellier 2 ; Place Eugène Bataillon; Montpellier , France
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MEK drives cyclin D1 hyperelevation during geroconversion. Cell Death Differ 2013; 20:1241-9. [PMID: 23852369 DOI: 10.1038/cdd.2013.86] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 06/06/2013] [Accepted: 06/07/2013] [Indexed: 12/26/2022] Open
Abstract
When the cell cycle becomes arrested, MTOR (mechanistic Target of Rapamycin) converts reversible arrest into senescence (geroconversion). Hyperexpression of cyclin D1 is a universal marker of senescence along with hypertrophy, beta-Gal staining and loss of replicative/regenerative potential (RP), namely, the ability to restart proliferation when the cell cycle is released. Inhibition of MTOR decelerates geroconversion, although only partially decreases cyclin D1. Here we show that in p21- and p16-induced senescence, inhibitors of mitogen-activated/extracellular signal-regulated kinase (MEK) (U0126, PD184352 and siRNA) completely prevented cyclin D1 accumulation, making it undetectable. We also used MEL10 cells in which MEK inhibitors do not inhibit MTOR. In such cells, U0126 by itself induced senescence that was remarkably cyclin D1 negative. In contrast, inhibition of cyclin-dependent kinase (CDK) 4/6 by PD0332991 caused cyclin D1-positive senescence in MEL10 cells. Both types of senescence were suppressed by rapamycin, converting it into reversible arrest. We confirmed that the inhibitor of CDK4/6 caused cyclin D1 positive senescence in normal RPE cells, whereas U0126 prevented cyclin D1 expression. Elimination of cyclin D1 by siRNA did not prevent other markers of senescence that are consistent with the lack of its effect on MTOR. Our data confirmed that a mere inhibition of the cell cycle was sufficient to cause senescence, providing MTOR was active, and inhibition of MEK partially inhibited MTOR in a cell-type-dependent manner. Second, hallmarks of senescence may be dissociated, and hyperelevated cyclin D1, a marker of hyperactivation of senescent cells, did not necessarily determine other markers of senescence. Third, inhibition of MEK was sufficient to eliminate cyclin D1, regardless of MTOR.
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Leontieva OV, Lenzo F, Demidenko ZN, Blagosklonny MV. Hyper-mitogenic drive coexists with mitotic incompetence in senescent cells. Cell Cycle 2012. [PMID: 23187803 PMCID: PMC3562309 DOI: 10.4161/cc.22937] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
When the cell cycle is arrested, even though growth-promoting pathways such as mTOR are still active, then cells senesce. For example, induction of either p21 or p16 arrests the cell cycle without inhibiting mTOR, which, in turn, converts p21/p16-induced arrest into senescence (geroconversion). Here we show that geroconversion is accompanied by dramatic accumulation of cyclin D1 followed by cyclin E and replicative stress. When p21 was switched off, senescent cells (despite their loss of proliferative potential) progressed through S phase, and levels of cyclins D1 and E dropped. Most cells entered mitosis and then died, either during mitotic arrest or after mitotic slippage, or underwent endoreduplication. Next, we investigated whether inhibition of mTOR would prevent accumulation of cyclins and loss of mitotic competence in p21-arrested cells. Both nutlin-3, which inhibits mTOR in these cells, and rapamycin suppressed geroconversion during p21-induced arrest, decelerated accumulation of cyclins D1 and E and decreased replicative stress. When p21 was switched off, cells successfully progressed through both S phase and mitosis. Also, senescent mouse embryonic fibroblasts (MEFs) overexpressed cyclin D1. After release from cell cycle arrest, senescent MEFs entered S phase but could not undergo mitosis and did not proliferate. We conclude that cellular senescence is characterized by futile hyper-mitogenic drive associated with mTOR-dependent mitotic incompetence.
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Affiliation(s)
- Olga V Leontieva
- Department of Cell Stress Biology, Roswell Park Cancer Institute, Buffalo, NY, USA
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