RESUMEN
RNA binding proteins (RBPs) are key arbiters of post-transcriptional regulation and are found to be found dysregulated in hematological malignancies. Here, we identify the RBP RBMX and its retrogene RBMXL1 to be required for murine and human myeloid leukemogenesis. RBMX/L1 are overexpressed in acute myeloid leukemia (AML) primary patients compared to healthy individuals, and RBMX/L1 loss delayed leukemia development. RBMX/L1 loss lead to significant changes in chromatin accessibility, as well as chromosomal breaks and gaps. We found that RBMX/L1 directly bind to mRNAs, affect transcription of multiple loci, including CBX5 (HP1α), and control the nascent transcription of the CBX5 locus. Forced CBX5 expression rescued the RBMX/L1 depletion effects on cell growth and apoptosis. Overall, we determine that RBMX/L1 control leukemia cell survival by regulating chromatin state through their downstream target CBX5. These findings identify a mechanism for RBPs directly promoting transcription and suggest RBMX/L1, as well as CBX5, as potential therapeutic targets in myeloid malignancies.
Asunto(s)
Cromatina , Leucemia Mieloide Aguda , Animales , Cromatina/genética , Regulación de la Expresión Génica , Ribonucleoproteínas Nucleares Heterogéneas/genética , Humanos , Leucemia Mieloide Aguda/genética , Ratones , Proteínas de Unión al ARN/genética , Factores de Transcripción/genéticaRESUMEN
Posttranscriptional regulation of mRNA is a powerful and tightly controlled process in which cells command the integrity, diversity, and abundance of their protein products. RNA-binding proteins (RBPs) are the principal players that control many intermediary steps of posttranscriptional regulation. Recent advances in this field have discovered the importance of RBPs in hematological diseases. Herein we will review a number of RBPs that have been determined to play critical functions in leukemia and lymphoma. Furthermore, we will discuss the potential therapeutic strategies that are currently being studied to specifically target RBPs in these diseases.
Asunto(s)
Leucemia/genética , Linfoma/genética , Proteínas de Unión al ARN/metabolismo , Regulación de la Expresión Génica , Humanos , Leucemia/terapia , Linfoma/terapia , Terapia Molecular Dirigida/métodos , ARN Mensajero/metabolismoRESUMEN
The cell-context dependency for RNA binding proteins (RBPs) mediated control of stem cell fate remains to be defined. Here we adapt the HyperTRIBE method using an RBP fused to a Drosophila RNA editing enzyme (ADAR) to globally map the mRNA targets of the RBP MSI2 in mammalian adult normal and malignant stem cells. We reveal a unique MUSASHI-2 (MSI2) mRNA binding network in hematopoietic stem cells that changes during transition to multipotent progenitors. Additionally, we discover a significant increase in RNA binding activity of MSI2 in leukemic stem cells compared with normal hematopoietic stem and progenitor cells, resulting in selective regulation of MSI2's oncogenic targets. This provides a basis for MSI2 increased dependency in leukemia cells compared to normal cells. Moreover, our study provides a way to measure RBP function in rare cells and suggests that RBPs can achieve differential binding activity during cell state transition independent of gene expression.
Asunto(s)
Diferenciación Celular/genética , Células Madre Hematopoyéticas/patología , Leucemia/genética , Células Madre Neoplásicas/patología , Proteínas de Unión al ARN/metabolismo , Adenosina Desaminasa/genética , Animales , Sitios de Unión/genética , Modelos Animales de Enfermedad , Proteínas de Drosophila/genética , Regulación Leucémica de la Expresión Génica , Redes Reguladoras de Genes , Células HEK293 , Humanos , Leucemia/sangre , Leucemia/patología , Ratones , Ratones Noqueados , Cultivo Primario de Células , ARN Mensajero/metabolismo , Proteínas de Unión al ARN/genética , RNA-Seq , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismoRESUMEN
The identity of the RNA-binding proteins (RBPs) that govern cancer stem cells remains poorly characterized. The MSI2 RBP is a central regulator of translation of cancer stem cell programs. Through proteomic analysis of the MSI2-interacting RBP network and functional shRNA screening, we identified 24 genes required for in vivo leukemia. Syncrip was the most differentially required gene between normal and myeloid leukemia cells. SYNCRIP depletion increased apoptosis and differentiation while delaying leukemogenesis. Gene expression profiling of SYNCRIP-depleted cells demonstrated a loss of the MLL and HOXA9 leukemia stem cell program. SYNCRIP and MSI2 interact indirectly though shared mRNA targets. SYNCRIP maintains HOXA9 translation, and MSI2 or HOXA9 overexpression rescued the effects of SYNCRIP depletion. Altogether, our data identify SYNCRIP as a new RBP that controls the myeloid leukemia stem cell program. We propose that targeting these RBP complexes might provide a novel therapeutic strategy in leukemia.
Asunto(s)
Regulación Leucémica de la Expresión Génica , Ribonucleoproteínas Nucleares Heterogéneas/genética , Leucemia Mieloide/genética , Proteínas de Unión al ARN/metabolismo , Animales , Supervivencia Celular , Femenino , Hematopoyesis/genética , Ribonucleoproteínas Nucleares Heterogéneas/metabolismo , Proteínas de Homeodominio/genética , Humanos , Leucemia Bifenotípica Aguda/genética , Leucemia Bifenotípica Aguda/patología , Leucemia Mieloide/patología , Ratones Endogámicos C57BL , Ratones Noqueados , Células Progenitoras Mieloides/metabolismo , Células Progenitoras Mieloides/patología , ARN Interferente Pequeño , Proteínas de Unión al ARN/genética , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
Myelodysplastic syndromes (MDS) are driven by complex genetic and epigenetic alterations. The MSI2 RNA-binding protein has been demonstrated to have a role in acute myeloid leukaemia and stem cell function, but its role in MDS is unknown. Here, we demonstrate that elevated MSI2 expression correlates with poor survival in MDS. Conditional deletion of Msi2 in a mouse model of MDS results in a rapid loss of MDS haematopoietic stem and progenitor cells (HSPCs) and reverses the clinical features of MDS. Inversely, inducible overexpression of MSI2 drives myeloid disease progression. The MDS HSPCs remain dependent on MSI2 expression after disease initiation. Furthermore, MSI2 expression expands and maintains a more activated (G1) MDS HSPC. Gene expression profiling of HSPCs from the MSI2 MDS mice identifies a signature that correlates with poor survival in MDS patients. Overall, we identify a role for MSI2 in MDS representing a therapeutic target in this disease.