Projet ANR-06-BLAN-0422 – DrosoBlood : Drosophila as a model system for haematopoiesis and leukaemia
Programme : Programme blanc (BLANC) 2006
Année de financement : 2006
Coordinateur du projet : UNIVERSITE PAUL SABATIER TOULOUSE 3 (UNIVERSITE PAUL SABATIER TOULOUSE 3)
Partenaires : Université de Toulouse III - Paul Sabatier
Montant : 250000.0 euros
Date de début : 2006
Durée : 36 mois
Résumé : Haematopoiesis involves commitment, proliferation and differentiation of a common progenitor into several specialised blood cell types that participate in a wide range of functions such as host defence against infection and haemostasis. Up-regulation of the haematopoietic system plays a critical role in establishing the proper response against invading pathogens, in removing cancerous cells or in tissue remodelling during normal development. Furthermore, deregulations of the haematopoietic differentiation program are at the origin of numerous diseases including leukaemia and lymphoma. Unravelling the genetic circuitry and the molecular mechanisms that control normal and pathological blood cell formation and differentiation is a major challenge. Recent evidence has shown that several features of haematopoietic development are conserved from Drosophila to vertebrates. Notably, transcription factors of the RUNX and GATA families, which play key roles in haematopoiesis in vertebrates, also control blood cell development in Drosophila.  Taking advantage of this phylogenetic conservation and of the powerful genetic tools available in Drosophila, we propose to use Drosophila haematopoiesis as a paradigm to study the function and molecular mechanisms of action of the GATA and RUNX transcription factors and to characterise new genes controlling the conserved aspects of haematopoiesis. First, we will use a recently developed genome-wide collection of UAS-dsRNA transgenic flies, from Dr R. Ueda to identify, in a large-scale genetic screen, the genes that control the different steps of Drosophila larval blood cell development. Furthermore, we have shown that the Drosophila orthologues of GATA1 and RUNX1, Serpent and Lozenge, interact physically and functionally to induce the differentiation of a particular blood cell type in vivo. Interestingly, this interaction is conserved in mammals in which it may also regulate blood cell development. To further characterize the molecular mechanisms of action and of cooperation between GATA and RUNX factors, we will perform a genome wide RNAi screen for modulators of Srp/Lz-induced transactivation in Drosophila S2 cells. Translocations or mutations affecting Runx1/AML1 are associated with the development of a large proportion of leukaemia in human. For instance the RUNX1-ETO translocation product is present in more than 10% of acute myeloid leukaemia, and the TEL-RUNX1 translocation is associated to 25% of acute lymphoblastic leukaemia. Another aspect of our project will be to use Drosophila as a model system to analyse the mode of action of these two oncogenic RUNX derivatives. In particular, we intend to perform both a molecular and a genetic screen to identify genes that control the activity of RUNX1-ETO and/or TEL-RUNX1. Similarly to the screen for modulators of Srp/Lz-induced transactivation, we will look for modulators of RUNX1-ETO or TEL-RUNX1-controlled transcription by RNAi on S2 cells. Furthermore, we will perform an in vivo screen using UAS-dsRNA transgenic flies to identify suppressors of TEL-RUNX1 and RUNX1-ETO-induced phenotype in vivo. The different genes identified in these screens will then be studied in depth in vitro and in vivo. In particular, we will characterise the function of these genes in Drosophila haematopoiesis and immune response. We will also elicit the analysis of their human orthologues during normal and leukaemic blood cell development. The completion of our project will allow the identification and the functional characterisation of several new factors that control the activity of GATA and RUNX transcription factors and/or haematopoiesis. Our results should shed new lights on the molecular mode of action of these transcription factors not only during Drosophila haematopoiesis but also in human haematopoietic development as well as in disease such as leukaemia. Hopefully, our results could also help to elaborate new therapeutic strategies.