"The deregulation of transcription is an important driver of leukemia development. Typically, transcription in leukemia cells is altered by the ectopic expression of transcription factors, by modulation of signaling pathways or by epigenetic changes. In addition to these factors that affect the production of RNAs, also changes in the processing of RNA (its splicing, transport and decay) may contribute to determine steady-state RNA levels in leukemia cells. Indeed, acquired mutations in various genes encoding RNA splice factors have recently been identified in myeloid leukemias and in chronic lymphocytic leukemia. In our study of T-cell acute lymphoblastic leukemia (T-ALL), we have identified mutations in RNA decay factors, including mutations in CNOT3, a protein believed to function in deadenylation of mRNA. It remains, however, unclear how mutations in RNA processing can contribute to the development of leukemia.In this project, we aim to further characterize the mechanisms of RNA regulation in T-cell acute lymphoblastic leukemia (T-ALL) to obtain insight in the interplay between RNA generation and RNA decay and its role in leukemia development. We will study RNA decay in human T-ALL cells and mouse models of T-ALL, with the aim to identify the molecular consequences that contribute to leukemia development. We will use new technologies such as RNA-sequencing in combination with bromouridine labeling of RNA to measure RNA transcription and decay rates in a transcriptome wide manner allowing unbiased discoveries. These studies will be complemented with screens in Drosophila melanogaster using an established eye cancer model, previously also successfully used for the studies of T-ALL oncogenes.This study will contribute to our understanding of the pathogenesis of T-ALL and may identify new targets for therapy of this leukemia. In addition, our study will provide a better understanding of how RNA processing is implicated in cancer development in general."