Browsing by Author "Chen, Sisi"

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    Access provided by IUPUI University Library, Indiana (Ruth Lilly) Altmetric: 0Citations: 2More detail Letter to the Editor Phosphatase PRL2 promotes AML1-ETO-induced acute myeloid leukemia
    (Nature, 2017) Kobayashi, Michihiro; Chen, Sisi; Bai, Yunpeng; Yao, Chonghua; Gao, Rui; Sun, Xiao-Jian; Mu, Chen; Twiggs, Taylor A.; Yu, Zhi-Hong; Boswell, H. Scott; Yoder, Mervin C.; Kapur, Reuben; Mulloy, James C.; Zhang, Zhong-Yin; Liu, Yan; Pediatrics, School of Medicine
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    Author Correction: Mutant p53 drives clonal hematopoiesis through modulating epigenetic pathway
    (Nature Publishing Group, 2020-07-28) Chen, Sisi; Wang, Qiang; Yu, Hao; Capitano, Maegan L.; Vemula, Sasidhar; Nabinger, Sarah C.; Gao, Rui; Yao, Chonghua; Kobayashi, Michihiro; Geng, Zhuangzhuang; Fahey, Aidan; Henley, Danielle; Liu, Stephen Z.; Barajas, Sergio; Cai, Wenjie; Wolf, Eric R.; Ramdas, Baskar; Cai, Zhigang; Gao, Hongyu; Luo, Na; Sun, Yang; Wong, Terrence N.; Link, Daniel C.; Liu, Yunlong; Boswell, H. Scott; Mayo, Lindsey D.; Huang, Gang; Kapur, Reuben; Yoder, Mervin C.; Broxmeyer, Hal E.; Gao, Zhonghua; Liu, Yan; Biochemistry and Molecular Biology, School of Medicine
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    Bmi1 promotes erythroid development through regulating ribosome biogenesis
    (Wiley, 2015-03) Gao, Rui; Chen, Sisi; Kobayashi, Michihiro; Yu, Hao; Zhang, Yingchi; Wan, Yang; Young, Sara K.; Soltis, Anthony; Yu, Ming; Vemula, Sasidhar; Fraenkel, Ernest; Cantor, Alan; Antipin, Yevgeniy; Xu, Yang; Yoder, Mervin C.; Wek, Ronald C.; Ellis, Steven R.; Kapur, Reuben; Zhu, Xiaofan; Liu, Yan; Department of Pediatrics, Indiana University School of Medicine
    While Polycomb group protein Bmi1 is important for stem cell maintenance, its role in lineage commitment is largely unknown. We have identified Bmi1 as a novel regulator of erythroid development. Bmi1 is highly expressed in mouse erythroid progenitor cells and its deficiency impairs erythroid differentiation. BMI1 is also important for human erythroid development. Furthermore, we discovered that loss of Bmi1 in erythroid progenitor cells results in decreased transcription of multiple ribosomal protein genes and impaired ribosome biogenesis. Bmi1 deficiency stabilizes p53 protein, leading to upregulation of p21 expression and subsequent G0/G1 cell cycle arrest. Genetic inhibition of p53 activity rescues the erythroid defects seen in the Bmi1 null mice, demonstrating that a p53-dependent mechanism underlies the pathophysiology of the anemia. Mechanistically, Bmi1 is associated with multiple ribosomal protein genes and may positively regulate their expression in erythroid progenitor cells. Thus, Bmi1 promotes erythroid development, at least in part through regulating ribosome biogenesis. Ribosomopathies are human disorders of ribosome dysfunction, including Diamond-Blackfan anemia (DBA) and 5q- syndrome, in which genetic abnormalities cause impaired ribosome biogenesis, resulting in specific clinical phenotypes. We observed that BMI1 expression in human hematopoietic stem and progenitor cells from patients with DBA is correlated with the expression of some ribosomal protein genes, suggesting that BMI1 deficiency may play a pathological role in DBA and other ribosomopathies.
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    Bmi1 Regulates Wnt Signaling in Hematopoietic Stem and Progenitor Cells
    (Springer, 2021) Yu, Hao; Gao, Rui; Chen, Sisi; Liu, Xicheng; Wang, Qiang; Cai, Wenjie; Vemula, Sasidhar; Fahey, Aidan C.; Henley, Danielle; Kobayashi, Michihiro; Liu, Stephen Z.; Qian, Zhijian; Kapur, Reuben; Broxmeyer, Hal E.; Gao, Zhonghua; Xi, Rongwen; Liu, Yan; Pediatrics, School of Medicine
    Polycomb group protein Bmi1 is essential for hematopoietic stem cell (HSC) self-renewal and terminal differentiation. However, its target genes in hematopoietic stem and progenitor cells are largely unknown. We performed gene expression profiling assays and found that genes of the Wnt signaling pathway are significantly elevated in Bmi1 null hematopoietic stem and progenitor cells (HSPCs). Bmi1 is associated with several genes of the Wnt signaling pathway in hematopoietic cells. Further, we found that Bmi1 represses Wnt gene expression in HSPCs. Importantly, loss of β-catenin, which reduces Wnt activation, partially rescues the HSC self-renewal and differentiation defects seen in the Bmi1 null mice. Thus, we have identified Bmi1 as a novel regulator of Wnt signaling pathway in HSPCs. Given that Wnt signaling pathway plays an important role in hematopoiesis, our studies suggest that modulating Wnt signaling may hold potential for enhancing HSC self-renewal, thereby improving the outcomes of HSC transplantation.
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    Genotoxic stresses promote clonal expansion of hematopoietic stem cells expressing mutant p53
    (Nature, 2018) Chen, Sisi; Gao, Rui; Yao, Chonghua; Kobayashi, Michihiro; Liu, Stephen Z.; Yoder, Mervin C.; Broxmeyer, Hal; Kapur, Reuben; Boswell, H. Scott; Mayo, Lindsey D.; Liu, Yan; Pediatrics, School of Medicine
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    Inhibition of Inflammatory Signaling in Tet2 Mutant Preleukemic Cells Mitigates Stress-Induced Abnormalities and Clonal Hematopoiesis
    (Elsevier, 2018-12-06) Cai, Zhigang; Kotzin, Jonathan J.; Ramdas, Baskar; Chen, Sisi; Nelanuthala, Sai; Palam, Lakshmi Reddy; Pandey, Ruchi; Mali, Raghuveer Singh; Liu, Yan; Kelley, Mark R.; Sandusky, George; Mohseni, Morvarid; Williams, Adam; Henao-Mejia, Jorge; Kapur, Reuben; Pediatrics, School of Medicine
    Inflammation is a risk factor for cancer development. Individuals with preleukemic TET2 mutations manifest clonal hematopoiesis and are at a higher risk of developing leukemia. How inflammatory signals influence the survival of preleukemic hematopoietic stem and progenitor cells (HSPCs) is unclear. We show a rapid increase in the frequency and absolute number of Tet2-KO mature myeloid cells and HSPCs in response to inflammatory stress, which results in enhanced production of inflammatory cytokines, including interleukin-6 (IL-6), and resistance to apoptosis. IL-6 induces hyperactivation of the Shp2-Stat3 signaling axis, resulting in increased expression of a novel anti-apoptotic long non-coding RNA (lncRNAs), Morrbid, in Tet2-KO myeloid cells and HSPCs. Expression of activated Shp2 in HSPCs phenocopies Tet2 loss with regard to hyperactivation of Stat3 and Morrbid. In vivo, pharmacologic inhibition of Shp2 or Stat3 or genetic loss of Morrbid in Tet2 mutant mice rescues inflammatory-stress-induced abnormalities in HSPCs and mature myeloid cells, including clonal hematopoiesis.
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    Mutant p53 drives clonal hematopoiesis through modulating epigenetic pathway
    (Nature Research, 2019-12-11) Chen, Sisi; Wang, Qiang; Yu, Hao; Capitano, Maegan L.; Vemula, Sasidhar; Nabinger, Sarah C.; Gao, Rui; Yao, Chonghua; Kobayashi, Michihiro; Geng, Zhuangzhuang; Fahey, Aidan; Henley, Danielle; Liu, Stephen Z.; Barajas, Sergio; Sergio, Wenjie; Wolf, Eric R.; Ramdas, Baskar; Cai, Zhigang; Gao, Hongyu; Luo, Na; Sun, Yang; Wong, Terrence N.; Link, Daniel C.; Liu, Yunlong; Boswell, H. Scott; Mayo, Lindsey D.; Huang, Gang; Kapur, Reuben; Yoder, Mervin C.; Broxmeyer, Hal E.; Gao, Zhonghua; Liu, Yan; Biochemistry and Molecular Biology, School of Medicine
    Clonal hematopoiesis of indeterminate potential (CHIP) increases with age and is associated with increased risks of hematological malignancies. While TP53 mutations have been identified in CHIP, the molecular mechanisms by which mutant p53 promotes hematopoietic stem and progenitor cell (HSPC) expansion are largely unknown. Here we discover that mutant p53 confers a competitive advantage to HSPCs following transplantation and promotes HSPC expansion after radiation-induced stress. Mechanistically, mutant p53 interacts with EZH2 and enhances its association with the chromatin, thereby increasing the levels of H3K27me3 in genes regulating HSPC self-renewal and differentiation. Furthermore, genetic and pharmacological inhibition of EZH2 decreases the repopulating potential of p53 mutant HSPCs. Thus, we uncover an epigenetic mechanism by which mutant p53 drives clonal hematopoiesis. Our work will likely establish epigenetic regulator EZH2 as a novel therapeutic target for preventing CHIP progression and treating hematological malignancies with TP53 mutations.
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    Mutant p53 enhances leukemia-initiating cell self-renewal to promote leukemia development
    (Nature, 2019-06) Nabinger, Sarah C.; Chen, Sisi; Gao, Rui; Yao, Chonghua; Kobayashi, Michihiro; Vemula, Sasidhar; Fahey, Aidan C.; Wang, Christine; Daniels, Cecil; Boswell, H. Scott; Sandusky, George E.; Mayo, Lindsey D.; Kapur, Reuben; Liu, Yan; Pediatrics, School of Medicine
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    Mutant P53 in pre-leukemic hematopoietic stem cells and the pathogenesis of Myelodysplastic Syndrome
    (2018-04) Chen, Sisi; Liu, Yan; Broxmeyer, Hal E.; Kapur, Reuben; Yoder, Mervin C.
    Myelodysplastic syndrome (MDS) is a clonal disease arising from mutated hematopoietic stem cells (HSCs). MDS stem cells originate from pre-leukemic HSCs, which have enhanced competitive advantage over wild-type (WT) HSCs but normal differentiation capacity. Recently, acquired somatic gain-of-function (GOF) TP53 mutations were identified in the blood of aged healthy individuals as well as in patients with MDS. However, the role of GOF TP53 mutations in clonal hematopoiesis and the pathogenesis of MDS is largely unknown. Based upon our previous studies and clinical findings, I hypothesized that GOF mutant p53 drives the development of pre-leukemic HSCs with enhanced competitive advantage, leading to clonal expansion and the pathogenesis of MDS. To test my hypothesis, I examined HSC behaviors in young p53+/+ and p53R248W/+ mice. I discovered that p53R248W enhances the repopulating potential of HSCs without affecting terminal differentiation. I also found that GOF mutant p53 protects HSCs from genotoxic stress and promotes their expansion. To investigate the role of mutant p53 in the pathogenesis of hematological malignancies, I monitored disease development in p53+/+ and p53R248W/+ mice and observed that some mutant p53 mice develop MDS during aging. Therefore, I demonstrated that GOF mutant p53 enhances the repopulating potential of HSCs and drives the development of pre-leukemic HSCs, predisposing aged mutant p53 mice to MDS development. Mechanistically, I found that mutant p53 increases the chromatin accessibility to genes important for HSC maintenance, including pluripotent gene Sox2 and chemokine gene Cxcl9. By performing biochemical experiments, I discovered that GOF mutant p53, but not WT p53, interacts with histone methyltransferase EZH2 and enhances histone H3 lysine 27 trimethylation (H3K27me3) at genes, including Mef/Elf4 and Gadd45g, that negatively regulate HSC self-renewal. Collectively, these findings demonstrated that GOF mutant p53 drives pre-leukemic HSC development through modulating epigenetic pathways. Thus, our studies have uncovered novel mechanistic and functional links between GOF mutant p53 and epigenetic regulators in pre-leukemic HSCs. This research may identify epigenetic regulator EZH2 as a novel target for the prevention and treatment of MDS patients with TP53 mutations.
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    Necdin modulates leukemia-initiating cell quiescence and chemotherapy response
    (Impact Journals, 2017-09-18) Yao, Chonghua; Kobayashi, Michihiro; Chen, Sisi; Nabinger, Sarah C.; Gao, Rui; Liu, Stephen Z.; Asai, Takashi; Liu, Yan; Pediatrics, School of Medicine
    Acute myeloid leukemia (AML) is a devastating illness which carries a very poor prognosis, with most patients living less than 18 months. Leukemia relapse may occur because current therapies eliminate proliferating leukemia cells but fail to eradicate quiescent leukemia-initiating cells (LICs) that can reinitiate the disease after a period of latency. While we demonstrated that p53 target gene Necdin maintains hematopoietic stem cell (HSC) quiescence, its roles in LIC quiescence and response to chemotherapy are unclear. In this study, we utilized two well-established murine models of human AML induced by MLL-AF9 or AML1-ETO9a to determine the role of Necdin in leukemogenesis. We found that loss of Necdin decreased the number of functional LICs and enhanced myeloid differentiation in vivo, leading to delayed development of leukemia induced by MLL-AF9. Importantly, Necdin null LICs expressing MLL-AF9 were less quiescent than wild-type LICs. Further, loss of Necdin enhanced the response of MLL-AF9+ leukemia cells to chemotherapy treatment, manifested by decreased viability and enhanced apoptosis. We observed decreased expression of Bcl2 and increased expression of p53 and its target gene Bax in Necdin null leukemia cells following chemotherapy treatment, indicating that p53-dependent apoptotic pathways may be activated in the absence of Necdin. In addition, we found that loss of Necdin decreased the engraftment of AML1-ETO9a+ hematopoietic stem and progenitor cells in transplantation assays. However, Necdin-deficiency did not affect the response of AML1-ETO9a+ hematopoietic cells to chemotherapy treatment. Thus, Necdin regulates leukemia-initiating cell quiescence and chemotherapy response in a context-dependent manner. Our findings suggest that pharmacological inhibition of Necdin may hold potential as a novel therapy for leukemia patients with MLL translocations.