RESUMO
Alterations in normal regulation of gene expression is one of the key features of hematopoietic malignancies. In order to gain insight into the mechanisms that regulate gene expression in these diseases, we dissected the role of the Ikaros protein in leukemia. Ikaros is a DNA-binding, zinc finger protein that functions as a transcriptional regulator and a tumor suppressor in leukemia. The use of ChIP-seq, RNA-seq, and ATAC-seq-coupled with functional experiments-revealed that Ikaros regulates both the global epigenomic landscape and epigenetic signature at promoter regions of its target genes. Casein kinase II (CK2), an oncogenic kinase that is overexpressed in leukemia, directly phosphorylates Ikaros at multiple, evolutionarily-conserved residues. Phosphorylation of Ikaros impairs the protein's ability to regulate both the transcription of its target genes and global epigenetic landscape in leukemia. Treatment of leukemia cells with a specific inhibitor of CK2 restores Ikaros function, resulting in cytotoxicity of leukemia cells. Here, we review the mechanisms through which the CK2-Ikaros signaling axis regulates the global epigenomic landscape and expression of genes that control cellular proliferation in leukemia.
Assuntos
Epigênese Genética , Regulação Leucêmica da Expressão Gênica , Neoplasias Hematológicas , Leucemia , Proteínas de Neoplasias , Transdução de Sinais , Proliferação de Células , Neoplasias Hematológicas/genética , Neoplasias Hematológicas/metabolismo , Neoplasias Hematológicas/patologia , Humanos , Leucemia/genética , Leucemia/metabolismo , Leucemia/patologia , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismoRESUMO
Signaling networks that regulate cellular proliferation often involve complex interactions between several signaling pathways. In this manuscript we review the crosstalk between the Casein Kinase II (CK2) and Glycogen Synthase Kinase-3 (GSK-3) pathways that plays a critical role in the regulation of cellular proliferation in leukemia. Both CK2 and GSK-3 are potential targets for anti-leukemia treatment. Previously published data suggest that CK2 and GSK-3 act synergistically to promote the phosphatidylinositol-3 kinase (PI3K) pathway via phosphorylation of PTEN. More recent data demonstrate another mechanism through which CK2 promotes the PI3K pathway - via transcriptional regulation of PI3K pathway genes by the newly-discovered CK2-Ikaros axis. Together, these data suggest that the CK2 and GSK-3 pathways regulate AKT/PI3K signaling in leukemia via two complementary mechanisms: a) direct phosphorylation of PTEN and b) transcriptional regulation of PI3K-promoting genes. Functional interactions between CK2, Ikaros and GSK3 define a novel signaling network that regulates proliferation of leukemia cells. This regulatory network involves both direct posttranslational modifications (by CK and GSK-3) and transcriptional regulation (via CK2-mediated phosphorylation of Ikaros). This information provides a basis for the development of targeted therapy for leukemia.
Assuntos
Caseína Quinase II/genética , Regulação Leucêmica da Expressão Gênica , Quinase 3 da Glicogênio Sintase/genética , Fator de Transcrição Ikaros/genética , Leucemia/genética , Antineoplásicos/uso terapêutico , Caseína Quinase II/metabolismo , Quinase 3 da Glicogênio Sintase/metabolismo , Humanos , Fator de Transcrição Ikaros/metabolismo , Leucemia/diagnóstico , Leucemia/tratamento farmacológico , Leucemia/mortalidade , PTEN Fosfo-Hidrolase/genética , PTEN Fosfo-Hidrolase/metabolismo , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/metabolismo , Fosforilação , Prognóstico , Transdução de Sinais , Análise de SobrevidaRESUMO
The IKZF1 gene encodes the Ikaros protein, a zinc finger transcriptional factor that acts as a master regulator of hematopoiesis and a tumor suppressor in leukemia. Impaired activity of Ikaros is associated with the development of high-risk acute lymphoblastic leukemia (ALL) with a poor prognosis. The molecular mechanisms that regulate Ikaros' function as a tumor suppressor and regulator of cellular proliferation are not well understood. We demonstrated that Ikaros is a substrate for Casein Kinase II (CK2), an oncogenic kinase that is overexpressed in ALL. Phosphorylation of Ikaros by CK2 impairs Ikaros' DNA-binding ability, as well as Ikaros' ability to regulate gene expression and function as a tumor suppressor in leukemia. Targeting CK2 with specific inhibitors restores Ikaros' function as a transcriptional regulator and tumor suppressor resulting in a therapeutic, anti-leukemia effect in a preclinical model of ALL. Here, we review the genes and pathways that are regulated by Ikaros and the molecular mechanisms through which Ikaros and CK2 regulate cellular proliferation in leukemia.
Assuntos
Caseína Quinase II/genética , Cromatina/imunologia , Fator de Transcrição Ikaros/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Linfócitos T/imunologia , Animais , Antineoplásicos/farmacologia , Caseína Quinase II/antagonistas & inibidores , Caseína Quinase II/imunologia , Ciclo Celular/efeitos dos fármacos , Ciclo Celular/genética , Proliferação de Células/efeitos dos fármacos , Cromatina/química , Cromatina/efeitos dos fármacos , Montagem e Desmontagem da Cromatina/efeitos dos fármacos , DNA Nucleotidilexotransferase/genética , DNA Nucleotidilexotransferase/imunologia , Regulação da Expressão Gênica , Humanos , Fator de Transcrição Ikaros/imunologia , Histona Desmetilases com o Domínio Jumonji/genética , Histona Desmetilases com o Domínio Jumonji/imunologia , Naftiridinas/farmacologia , Proteínas Nucleares/genética , Proteínas Nucleares/imunologia , Fenazinas , Fosforilação/efeitos dos fármacos , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Leucemia-Linfoma Linfoblástico de Células Precursoras/imunologia , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologia , Proteínas Repressoras/genética , Proteínas Repressoras/imunologia , Transdução de Sinais , Linfócitos T/efeitos dos fármacos , Linfócitos T/patologiaRESUMO
BACKGROUND/AIM: Langmuir-Blodgett (LB) films used as templates for crystallization lead to marked changes in protein stability and water dehydration, despite slight changes in protein atomic structure. Herein, we discuss the importance of LB-based nanocrystallography at the frontiers of cancer proteomics focusing on two model proteins with important biological roles in cancer, namely CK2alpha and RNase A. MATERIALS AND METHODS: Computational mutagenesis using the KINARI Mutagen webserver exhibits different behaviors in terms of stability and robustness, as well as in terms of water dynamics. CONCLUSION: Introduction of LB film leads to the appearance of water molecules close to the protein surface with larger volume, causing changes in crystal stability against radiation and appearing replicated in mutant proteins. Implications for drug design, drug delivery and cancer-causing protein variants are herein presented, along with a review of the most recent findings in LB-based nanobiocrystallography.