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Risal S, Adhikari D, Liu K. Animal Models for Studying the In Vivo Functions of Cell Cycle CDKs. Methods Mol Biol 2016; 1336:155-66. [PMID: 26231715 DOI: 10.1007/978-1-4939-2926-9_13] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Multiple Cdks (Cdk4, Cdk6, and Cdk2) and a mitotic Cdk (Cdk1) are involved in cell cycle progression in mammals. Cyclins, Cdk inhibitors, and phosphorylations (both activating and inhibitory) at different cellular levels tightly modulate the activities of these kinases. Based on the results of biochemical studies, it was long believed that different Cdks functioned at specific stages during cell cycle progression. However, deletion of all three interphase Cdks in mice affected cell cycle entry and progression only in certain specialized cells such as hematopoietic cells, beta cells of the pancreas, pituitary lactotrophs, and cardiomyocytes. These genetic experiments challenged the prevailing biochemical model and established that Cdks function in a cell-specific, but not a stage-specific, manner during cell cycle entry and the progression of mitosis. Recent in vivo studies have further established that Cdk1 is the only Cdk that is both essential and sufficient for driving the resumption of meiosis during mouse oocyte maturation. These genetic studies suggest a minimal-essential cell cycle model in which Cdk1 is the central regulator of cell cycle progression. Cdk1 can compensate for the loss of the interphase Cdks by forming active complexes with A-, B-, E-, and D-type Cyclins in a stepwise manner. Thus, Cdk1 plays an essential role in both mitosis and meiosis in mammals, whereas interphase Cdks are dispensable.
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Affiliation(s)
- Sanjiv Risal
- Department of Chemistry and Molecular Biology, University of Gothenburg, 462, 405 30, Gothenburg, Sweden,
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p19Ink4d is a tumor suppressor and controls pituitary anterior lobe cell proliferation. Mol Cell Biol 2014; 34:2121-34. [PMID: 24687853 DOI: 10.1128/mcb.01363-13] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pituitary tumors develop in about one-quarter of the population, and most arise from the anterior lobe (AL). The pituitary gland is particularly sensitive to genetic alteration of genes involved in the cyclin-dependent kinase (CDK) inhibitor (CKI)-CDK-retinoblastoma protein (Rb) pathway. Mice heterozygous for the Rb mutation develop pituitary tumors, with about 20% arising from the AL. Perplexingly, none of the CKI-deficient mice reported thus far develop pituitary AL tumors. In this study, we show that deletion of p19(Ink4d) (p19), a CKI gene, in mice results in spontaneous development of tumors in multiple organs and tissues. Specifically, more than one-half of the mutant mice developed pituitary hyperplasia or tumors predominantly in the AL. Tumor development is associated with increased cell proliferation and enhanced activity of Cdk4 and Cdk6 and phosphorylation of Rb protein. Though Cdk4 is indispensable for postnatal pituitary cell proliferation, it is not required for the hyperproliferative pituitary phenotype caused by p19 loss. Loss of p19 phosphorylates Rb in Cdk4(-/-) pituitary AL cells and mouse embryonic fibroblasts (MEFs) and rescues their proliferation defects, at least partially, through the activation of Cdk6. These results provide the first genetic evidence that p19 is a tumor suppressor and the major CKI gene that controls pituitary AL cell proliferation.
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Ma L, Buchold GM, Greenbaum MP, Roy A, Burns KH, Zhu H, Han DY, Harris RA, Coarfa C, Gunaratne PH, Yan W, Matzuk MM. GASZ is essential for male meiosis and suppression of retrotransposon expression in the male germline. PLoS Genet 2009; 5:e1000635. [PMID: 19730684 PMCID: PMC2727916 DOI: 10.1371/journal.pgen.1000635] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2009] [Accepted: 08/06/2009] [Indexed: 11/18/2022] Open
Abstract
Nuage are amorphous ultrastructural granules in the cytoplasm of male germ cells as divergent as Drosophila, Xenopus, and Homo sapiens. Most nuage are cytoplasmic ribonucleoprotein structures implicated in diverse RNA metabolism including the regulation of PIWI-interacting RNA (piRNA) synthesis by the PIWI family (i.e., MILI, MIWI2, and MIWI). MILI is prominent in embryonic and early post-natal germ cells in nuage also called germinal granules that are often associated with mitochondria and called intermitochondrial cement. We find that GASZ (Germ cell protein with Ankyrin repeats, Sterile alpha motif, and leucine Zipper) co-localizes with MILI in intermitochondrial cement. Knockout of Gasz in mice results in a dramatic downregulation of MILI, and phenocopies the zygotene-pachytene spermatocyte block and male sterility defect observed in MILI null mice. In Gasz null testes, we observe increased hypomethylation and expression of retrotransposons similar to MILI null testes. We also find global shifts in the small RNAome, including down-regulation of repeat-associated, known, and novel piRNAs. These studies provide the first evidence for an essential structural role for GASZ in male fertility and epigenetic and post-transcriptional silencing of retrotransposons by stabilizing MILI in nuage.
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Affiliation(s)
- Lang Ma
- Department of Pathology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Gregory M. Buchold
- Department of Pathology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Michael P. Greenbaum
- Department of Pathology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Angshumoy Roy
- Department of Pathology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Kathleen H. Burns
- Department of Pathology, The Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America
| | - Huifeng Zhu
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Derek Y. Han
- Department of Pathology, Baylor College of Medicine, Houston, Texas, United States of America
| | - R. Alan Harris
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, United States of America
| | - Cristian Coarfa
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, United States of America
| | - Preethi H. Gunaratne
- Department of Pathology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Wei Yan
- Department of Pathology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Martin M. Matzuk
- Department of Pathology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Pathology, The Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America
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Reddy NM, Kleeberger SR, Bream JH, Fallon PG, Kensler TW, Yamamoto M, Reddy SP. Genetic disruption of the Nrf2 compromises cell-cycle progression by impairing GSH-induced redox signaling. Oncogene 2008; 27:5821-32. [PMID: 18542053 PMCID: PMC2646365 DOI: 10.1038/onc.2008.188] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2007] [Revised: 05/05/2008] [Accepted: 05/12/2008] [Indexed: 01/10/2023]
Abstract
Genetic disruption of Nrf2 greatly enhances susceptibility to prooxidant- and carcinogen-induced experimental models of various human disorders; but the mechanisms by which this transcription factor confers protection are unclear. Using Nrf2-proficient (Nrf2(+/+)) and Nrf2-deficient (Nrf2(-/-)) primary epithelial cultures as a model, we now show that Nrf2 deficiency leads to oxidative stress and DNA lesions, accompanied by impairment of cell-cycle progression, mainly G(2)/M-phase arrest. Both N-acetylcysteine and glutathione (GSH) supplementation ablated the DNA lesions and DNA damage-response pathways in Nrf2(-/-) cells; however only GSH could rescue the impaired colocalization of mitosis-promoting factors and the growth arrest. Akt activation was deregulated in Nrf2(-/-) cells, but GSH supplementation restored it. Inhibition of Akt signaling greatly diminished the GSH-induced Nrf2(-/-) cell proliferation and wild-type cell proliferation. GSH depletion impaired Akt signaling and mitosis-promoting factor colocalization in Nrf2(+/+) cells. Collectively, our findings uncover novel functions for Nrf2 in regulating oxidative stress-induced cell-cycle arrest, especially G(2)/M-checkpoint arrest, and proliferation, and GSH-regulated redox signaling and Akt are required for this process.
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Affiliation(s)
- NM Reddy
- Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - SR Kleeberger
- National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, USA
| | - JH Bream
- Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - PG Fallon
- Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - TW Kensler
- Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - M Yamamoto
- Department of Medical Biochemistry, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - SP Reddy
- Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
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