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Zhang C, Hoang N, Leng F, Saxena L, Lee L, Alejo S, Qi D, Khal A, Sun H, Lu F, Zhang H. LSD1 demethylase and the methyl-binding protein PHF20L1 prevent SET7 methyltransferase-dependent proteolysis of the stem-cell protein SOX2. J Biol Chem 2018; 293:3663-3674. [PMID: 29358331 DOI: 10.1074/jbc.ra117.000342] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 01/12/2018] [Indexed: 11/06/2022] Open
Abstract
The pluripotency-controlling stem-cell protein SRY-box 2 (SOX2) plays a pivotal role in maintaining the self-renewal and pluripotency of embryonic stem cells and also of teratocarcinoma or embryonic carcinoma cells. SOX2 is monomethylated at lysine 119 (Lys-119) in mouse embryonic stem cells by the SET7 methyltransferase, and this methylation triggers ubiquitin-dependent SOX2 proteolysis. However, the molecular regulators and mechanisms controlling SET7-induced SOX2 proteolysis are unknown. Here, we report that in human ovarian teratocarcinoma PA-1 cells, methylation-dependent SOX2 proteolysis is dynamically regulated by the LSD1 lysine demethylase and a methyl-binding protein, PHD finger protein 20-like 1 (PHF20L1). We found that LSD1 not only removes the methyl group from monomethylated Lys-117 (equivalent to Lys-119 in mouse SOX2), but it also demethylates monomethylated Lys-42 in SOX2, a reaction that SET7 also regulated and that also triggered SOX2 proteolysis. Our studies further revealed that PHF20L1 binds both monomethylated Lys-42 and Lys-117 in SOX2 and thereby prevents SOX2 proteolysis. Down-regulation of either LSD1 or PHF20L1 promoted SOX2 proteolysis, which was prevented by SET7 inactivation in both PA-1 and mouse embryonic stem cells. Our studies also disclosed that LSD1 and PHF20L1 normally regulate the growth of pluripotent mouse embryonic stem cells and PA-1 cells by preventing methylation-dependent SOX2 proteolysis. In conclusion, our findings reveal an important mechanism by which the stability of the pluripotency-controlling stem-cell protein SOX2 is dynamically regulated by the activities of SET7, LSD1, and PHF20L1 in pluripotent stem cells.
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Affiliation(s)
- Chunxiao Zhang
- From the Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, Nevada 89154 and.,the Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China
| | - Nam Hoang
- From the Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, Nevada 89154 and
| | - Feng Leng
- From the Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, Nevada 89154 and.,the Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China
| | - Lovely Saxena
- From the Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, Nevada 89154 and
| | - Logan Lee
- From the Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, Nevada 89154 and
| | - Salvador Alejo
- From the Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, Nevada 89154 and
| | - Dandan Qi
- From the Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, Nevada 89154 and.,the Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China
| | - Anthony Khal
- From the Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, Nevada 89154 and
| | - Hong Sun
- From the Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, Nevada 89154 and
| | - Fei Lu
- the Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China
| | - Hui Zhang
- From the Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, Nevada 89154 and
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Leukemic survival factor SALL4 contributes to defective DNA damage repair. Oncogene 2016; 35:6087-6095. [PMID: 27132514 PMCID: PMC5093088 DOI: 10.1038/onc.2016.146] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 02/25/2016] [Accepted: 03/24/2016] [Indexed: 12/12/2022]
Abstract
SALL4 is aberrantly expressed in human myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). We have generated a SALL4 transgenic (SALL4B Tg) mouse model with pre-leukemic MDS-like symptoms that transform to AML over time. This makes our mouse model applicable for studying human MDS/AML diseases. Characterization of the leukemic initiation population in this model leads to the discovery that Fancl (Fanconi anemia, complementation group L) is downregulated in SALL4B Tg leukemic and pre-leukemic cells. Similar to the reported Fanconi anemia (FA) mouse model, chromosomal instability with radial changes can be detected in pre-leukemic SALL4B Tg bone marrow (BM) cells after DNA damage challenge. Results from additional studies using DNA damage repair reporter assays support a role of SALL4 in inhibiting the homologous recombination pathway. Intriguingly, unlike the FA mouse model, after DNA damage challenge, SALL4B Tg BM cells can survive and generate hematopoietic colonies. We further elucidated that the mechanism by which SALL4 promotes cell survival is through Bcl2 activation. Overall, our studies demonstrate for the first time that SALL4 has a negative impact in DNA damage repair, and support the model of dual functional properties of SALL4 in leukemogenesis through inhibiting DNA damage repair and promoting cell survival.
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Stevens JB, Abdallah BY, Regan SM, Liu G, Bremer SW, Ye CJ, Heng HH. Comparison of mitotic cell death by chromosome fragmentation to premature chromosome condensation. Mol Cytogenet 2010; 3:20. [PMID: 20959006 PMCID: PMC2974731 DOI: 10.1186/1755-8166-3-20] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2010] [Accepted: 10/19/2010] [Indexed: 11/17/2022] Open
Abstract
Mitotic cell death is an important form of cell death, particularly in cancer. Chromosome fragmentation is a major form of mitotic cell death which is identifiable during common cytogenetic analysis by its unique phenotype of progressively degraded chromosomes. This morphology however, can appear similar to the morphology of premature chromosome condensation (PCC) and thus, PCC has been at times confused with chromosome fragmentation. In this analysis the phenomena of chromosome fragmentation and PCC are reviewed and their similarities and differences are discussed in order to facilitate differentiation of the similar morphologies. Furthermore, chromosome pulverization, which has been used almost synonymously with PCC, is re-examined. Interestingly, many past reports of chromosome pulverization are identified here as chromosome fragmentation and not PCC. These reports describe broad ranging mechanisms of pulverization induction and agree with recent evidence showing chromosome fragmentation is a cellular response to stress. Finally, biological aspects of chromosome fragmentation are discussed, including its application as one form of non-clonal chromosome aberration (NCCA), the driving force of cancer evolution.
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Affiliation(s)
- Joshua B Stevens
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, USA
| | - Batoul Y Abdallah
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, USA
| | - Sarah M Regan
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, USA
| | - Guo Liu
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, USA
| | - Steven W Bremer
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, USA
| | - Christine J Ye
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, USA
| | - Henry H Heng
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, USA
- Karmanos Cancer Institute, Detroit, USA
- Department of Pathology, Wayne State University School of Medicine, Detroit, USA
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