The physiologic roles of death receptor-controlled cell death pathways within the myeloid and erythroid haematopoiesis in transgenic mouse models

Erwin Schrödinger Fellowship J 1921 Death receptor pathways in hemopoiesis of transgenic mice Alexander EGLE 08.05.2000 Evidence has accumulated for a prominent role of death receptor signaling in the regulation of hematopoietic cell survival and function. Some of the shortcomings of the evidence from in vitro results could be overcome by the utifisation of transgenic mouse models. However, the studies carried out so far have been hampered by the early lethality of knock-out or transgenic mice with disabled death receptor pathways. The proposed project will utilize a vav-promoter driven transgenic vector, that is able to direct the expression of a transgene to all cells of the hematopoietic system, to generate transgenic animals with a targetted disruption of the death receptor pathways exclusively within the hematopoietic cell lineages. As in the previously published studies on mice with targetted death receptor pathways early lethality did not involve limiting affections of the hematopoietic systems, it is expected that viable mice can be obtained with this approach to study the influence of disruption of death receptor signaling on the mature erythroid and myeloid hematopoiesis in mice, since published data on these compartments hint on a major involvement of death receptors in their regulation. Based on their vast experience in this field, mice wiff be generated by the Walter and Eliza Hall Institute in Melbourne, Australia. To block the signalling of death receptor signals in all hematpoietic cells, the following vavP-driven transgenes will be employed: dominant negative versions of FADD, caspase-8 and -9, a transgene encoding FLIEP (a natural physiologic inhibitor of caspase-8) or the general caspase inhibitor p35. The mice obtained thereby will then be investigated by classic hematologictmorpholgic procedures to study myelo- and erythropoiesis and compared to normal littermates and to the vavP-bcl2 transgenic mice available. In further studies cell biologic analyses will address questions regarding the functional capabilities of the hematopoietic cells obtained from the transgenic animals with special regard to their responses to proapoptotic stimuli.