Functional examination of H3K4 methyltransferases in myeloid neoplasia

点击翻译按钮获取中文摘要

Perturbations of epigenetic regulation are profoundly linked with tumorigenesis. The enzymes that methylate histone tails, particularly those involved in the opposition between Trithorax- and Polycomb-Groups, are central to epigenetic regulation and frequently mutated in many cancers.We have made conditional mouse lines for all six histone 3 lysine 4 (H3K4) Trithorax-Group methyltransferases and are systematically examining their roles during development, in the germline and in the adult. These six include the major leukemogenic factor MLL1, its sister gene MLL2, and SETD1B. Here we propose work based on our recent findings that loss of either Setd1b or Mll2 in adult mice provokes myeloid neoplasia. Our findings, together with the known role of Mll1 in the maintenance of hematopoietic stem cells (HSCs) and the prominence of MLL3 and MLL4 mutations in recent human cancer exome studies, raise a new imperative for studies to understand the Trithorax-Group in hematopoiesis. Furthermore, we believe that our work will strongly contribute to and benefit from interactions with other SPP1463 partners, particularly those working on MLL1, Polycomb-Group and DNA methylation. Overall, a substantially integrated understanding of the major epigenetic regulators in the myeloid lineage can be obtained. Our recent data indicate that Setd1b deletion in adult mice produces myeloproliferative neoplasia with features of human chronic myelomonocytic leukemia (CMML), and Mll2 deletion produces a mild myeloid malignancy. On the basis of these preliminary data, we plan to evaluate the HSC and hematopoietic progenitor compartments in conditionally mutated Setd1b, Mll2 and double Setd1b/Mll2 mice. We predict intrinsic defects in HSCs, which results in skewing of differentiation toward the myeloid lineage and therefore plan to perform bone marrow transplantation studies. To gain insight into the molecular basis of the hematopoietic defect, we will generate total mRNA expression profiles comparing Setd1b, Mll2 and double Setd1b/Mll2 conditional knockouts versus control HSCs, complemented by H3K4me3, -me2 and -me1 chromatin immunoprecipitations (ChIPs) from HSC and progenitor cell populations. We will complement the mouse work with comparative structure-function analyses to explain the inherent myeloid transformation potential of Setd1b using BAC transgenesis for exon swaps between Setd1a and Setd1b.By comparison of Setd1b and Mll2, we aim to integrate a systematic understanding of H3K4 methyltransferase action in the myeloid lineage with the Polycomb-Group and DNA methylation knowledge generated by other SPP1463 partners. Furthermore, we offer a workshop on our recombineering, BAC transgenic and generic protein tagging methodologies to this SPP.