Our recent studies indicate that the DNA binding factor Ikaros is required for pre-B cell transition from a proliferating to a differentiating phase. Upon Ikaros loss there is a dramatic accumulation of large proliferating pre-B cells and a block at this developmental stage. Proliferating pre-B cell are considered the normal developmental counterpart of B cell acute lymphoblastic leukemia (B-ALL), and a block at this stage potentially tumorigenic. IKAROS is frequently inactivated in human B-ALL, and its loss is observed in the majority of BCR-ABL B-ALL, defining a particularly aggressive and hard-to-treat leukemia. Here, we propose to establish the cellular and molecular pathways supported by Ikaros during pre-B cell differentiation and delineate the regulatory mechanisms involved. Ikaros is an integral component of a chromatin remodeling complex and functions by modulating chromatin in the vicinity of its target sites. Therefore part of this study aims at understanding the epigenetic regulation of the normal, pre- leukemic, and leukemic pre-B cell stages. In the first specific aim, we will delineate the effects of Ikaros loss on the cellular and molecular pathways that control transition through the pre-B cell stage. We will examine whether and how activity of Ikaros-dependent pre-B cell pathways are further modulated by BCR-ABL and establish a potential synergism or co-operation between the two factors in B-ALL. In the second aim, we will establish the gene networks that are directly regulated by Ikaros and the epigenetic mechanisms employed. Ikaros effects on chromatin accessibility at its gene target sites and on recruitment of other key transcriptional and chromatin regulators of this process will be evaluated. We will also evaluate whether the Ikaros-based regulatory process is also controlled by BCR-ABL. New genetic models based on Ikaros loss-of-function and gain of function for BCR-ABL will be combined with cutting-edge genome-wide gene expression, chromatin and signaling approaches to delineate the epigenetic, transcription and signaling networks effected by these factors during normal B cell differentiation and leukemia development. Exploitation of the Ikaros gene targets or their transcriptional and epigenetic mechanisms of regulation may empower the design of new intelligent/tailored diagnostics and therapies for high-risk B-ALL. .

Public Health Relevance

Here we investigate the mechanisms by which the nuclear protein Ikaros controls normal development of B cells. We study how cancers with an immature B cell phenotype develop when Ikaros function fail sat this stage. Understanding how Ikaros works in normal and abnormal B cell development can empower the design of new intelligent and tailored diagnostics and therapies to cure lymphoid cancers.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA162092-22
Application #
8699508
Study Section
Molecular and Cellular Hematology (MCH)
Program Officer
Howcroft, Thomas K
Project Start
2011-09-01
Project End
2016-07-31
Budget Start
2014-08-01
Budget End
2015-07-31
Support Year
22
Fiscal Year
2014
Total Cost
Indirect Cost
Name
Massachusetts General Hospital
Department
Type
DUNS #
City
Boston
State
MA
Country
United States
Zip Code
02199
Hu, Yeguang; Yoshida, Toshimi; Georgopoulos, Katia (2017) Transcriptional circuits in B cell transformation. Curr Opin Hematol 24:345-352
Georgopoulos, Katia (2017) The making of a lymphocyte: the choice among disparate cell fates and the IKAROS enigma. Genes Dev 31:439-450
Georgopoulos, Katia (2017) In search of the mechanism that shapes the neutrophil's nucleus. Genes Dev 31:85-87
Hu, Yeguang; Zhang, Zhihong; Kashiwagi, Mariko et al. (2016) Superenhancer reprogramming drives a B-cell-epithelial transition and high-risk leukemia. Genes Dev 30:1971-90
Georgopoulos, Katia (2016) Induction of Bcl11b during T cell commitment through a tripartite mechanism. Nat Immunol 17:903-4
Perotti, Elizabeth A; Georgopoulos, Katia; Yoshida, Toshimi (2015) An Ikaros Promoter Element with Dual Epigenetic and Transcriptional Activities. PLoS One 10:e0131568
Yoshida, Toshimi; Georgopoulos, Katia (2014) Ikaros fingers on lymphocyte differentiation. Int J Hematol 100:220-9
Joshi, Ila; Yoshida, Toshimi; Jena, Nilamani et al. (2014) Loss of Ikaros DNA-binding function confers integrin-dependent survival on pre-B cells and progression to acute lymphoblastic leukemia. Nat Immunol 15:294-304
Yoshida, Toshimi; Landhuis, Esther; Dose, Marei et al. (2013) Transcriptional regulation of the Ikzf1 locus. Blood 122:3149-59
Zhang, Jiangwen; Jackson, Audrey F; Naito, Taku et al. (2011) Harnessing of the nucleosome-remodeling-deacetylase complex controls lymphocyte development and prevents leukemogenesis. Nat Immunol 13:86-94

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