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Choi H, Kang C. Living Beyond Restriction: LBR promotes cellular immortalization by suppressing genomic instability and senescence. FEBS J 2024. [PMID: 38646863 DOI: 10.1111/febs.17141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Accepted: 04/10/2024] [Indexed: 04/23/2024]
Abstract
Cellular immortalization is a complex process that requires multiple genetic alterations to overcome restricting barriers, including senescence. Not surprisingly, many of these alterations are associated with cancer; two tumor suppressor pathways, the cellular tumor antigen p53 and p16-Retinoblastoma (RB) pathways, are the best-characterized examples, but their mutations alone are known to be insufficient to drive full immortalization. En et al. identified a role for the lamin B receptor (LBR) in promoting cellular proliferation and immortalization in p53- and RB-deficient cells by maintaining their genome integrity and suppressing senescence. Thus, modulation of LBR could be exploited to treat cancer and potentially also to promote cell rejuvenation.
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Affiliation(s)
- Haebeen Choi
- School of Biological Sciences, Seoul National University, South Korea
- Center for Systems Geroscience, Seoul National University, South Korea
| | - Chanhee Kang
- School of Biological Sciences, Seoul National University, South Korea
- Center for Systems Geroscience, Seoul National University, South Korea
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En A, Takemoto K, Yamakami Y, Nakabayashi K, Fujii M. Upregulated expression of lamin B receptor increases cell proliferation and suppresses genomic instability: implications for cellular immortalization. FEBS J 2024. [PMID: 38462947 DOI: 10.1111/febs.17113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 01/04/2024] [Accepted: 02/28/2024] [Indexed: 03/12/2024]
Abstract
Mammalian somatic cells undergo terminal proliferation arrest after a limited number of cell divisions, a phenomenon termed cellular senescence. However, cells acquire the ability to proliferate infinitely (cellular immortalization) through multiple genetic alterations. Inactivation of tumor suppressor genes such as p53, RB and p16 is important for cellular immortalization, although additional molecular alterations are required for cellular immortalization to occur. Here, we aimed to gain insights into these molecular alterations. Given that cellular immortalization is the escape of cells from cellular senescence, genes that regulate cellular senescence are likely to be involved in cellular immortalization. Because senescent cells show altered heterochromatin organization, we investigated the implications of lamin A/C, lamin B1 and lamin B receptor (LBR), which regulate heterochromatin organization, in cellular immortalization. We employed human immortalized cell lines, KMST-6 and SUSM-1, and found that expression of LBR was upregulated upon cellular immortalization and downregulated upon cellular senescence. In addition, knockdown of LBR induced cellular senescence with altered chromatin configuration. Additionally, enforced expression of LBR increased cell proliferation likely through suppression of genome instability in human primary fibroblasts that expressed the simian virus 40 large T antigen (TAg), which inactivates p53 and RB. Furthermore, expression of TAg or knockdown of p53 led to upregulated LBR expression. These observations suggested that expression of LBR might be upregulated to suppress genome instability in TAg-expressing cells, and, consequently, its upregulated expression assisted the proliferation of TAg-expressing cells (i.e. p53/RB-defective cells). Our findings suggest a crucial role for LBR in the process of cellular immortalization.
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Affiliation(s)
- Atsuki En
- Graduate School of Nanobioscience, Yokohama City University, Japan
| | - Kentaro Takemoto
- Graduate School of Nanobioscience, Yokohama City University, Japan
| | - Yoshimi Yamakami
- Graduate School of Nanobioscience, Yokohama City University, Japan
| | - Kazuhiko Nakabayashi
- Department of Maternal-Fetal Biology, National Center for Child Health and Development, Tokyo, Japan
| | - Michihiko Fujii
- Graduate School of Nanobioscience, Yokohama City University, Japan
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Takauji Y, Kudo I, En A, Matsuo R, Hossain MN, Nakabayashi K, Miki K, Fujii M, Ayusawa D. GNG11 (G-protein subunit γ 11) suppresses cell growth with induction of reactive oxygen species and abnormal nuclear morphology in human SUSM-1 cells. Biochem Cell Biol 2017; 95:517-523. [PMID: 28380310 DOI: 10.1139/bcb-2016-0248] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Enforced expression of GNG11, G-protein subunit γ 11, induces cellular senescence in normal human diploid fibroblasts. We here examined the effect of the expression of GNG11 on the growth of immortalized human cell lines, and found that it suppressed the growth of SUSM-1 cells, but not of HeLa cells. We then compared these two cell lines to understand the molecular basis for the action of GNG11. We found that expression of GNG11 induced the generation of reactive oxygen species (ROS) and abnormal nuclear morphology in SUSM-1 cells but not in HeLa cells. Increased ROS generation by GNG11 would likely be caused by the down-regulation of the antioxidant enzymes in SUSM-1 cells. We also found that SUSM-1 cells, even under normal culture conditions, showed higher levels of ROS and higher incidence of abnormal nuclear morphology than HeLa cells, and that abnormal nuclear morphology was relevant to the increased ROS generation in SUSM-1 cells. Thus, SUSM-1 and HeLa cells showed differences in the regulation of ROS and nuclear morphology, which might account for their different responses to the expression of GNG11. Thus, SUSM-1 cells may provide a unique system to study the regulatory relationship between ROS generation, nuclear morphology, and G-protein signaling.
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Affiliation(s)
- Yuki Takauji
- a Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama, Kanagawa 236-0027, Japan
| | - Ikuru Kudo
- a Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama, Kanagawa 236-0027, Japan
| | - Atsuki En
- a Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama, Kanagawa 236-0027, Japan
| | - Ryo Matsuo
- a Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama, Kanagawa 236-0027, Japan
| | - Mohammad Nazir Hossain
- b Department of Biochemistry, Primeasia University, 9 Banani C/A Banani, Dhaka 1213, Bangladesh
| | - Kazuhiko Nakabayashi
- c Department of Maternal-Fetal Biology, National Center for Child Health and Development, Tokyo 157-8535, Japan
| | - Kensuke Miki
- a Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama, Kanagawa 236-0027, Japan.,d Ichiban Life Corporation, 1-1-7 Horai-cho, Naka-ku, Yokohama, Kanagawa 231-0048, Japan
| | - Michihiko Fujii
- a Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama, Kanagawa 236-0027, Japan
| | - Dai Ayusawa
- a Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama, Kanagawa 236-0027, Japan.,d Ichiban Life Corporation, 1-1-7 Horai-cho, Naka-ku, Yokohama, Kanagawa 231-0048, Japan
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