Study of CALR del52 and ins5 knock-in mouse models and comparison to the JAK2V617F knock-in mouse model

Abstract

Myeloproliferative neoplasms (MPN) are haematological disorders characterized by increased proliferation and accumulation of mature myeloid cells of one or more of the myeloid series (granulocytic, erythroid or megakaryocytic). Among the MPN are polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF). Patients with these disorders may present the JAK2V617F mutation which occurs in 95% of cases of PV and 50% of cases of ET and PMF. Recently a new mutation has been associated to MPN, this mutation occur on Calreticulin gene (CALR) and is present in 60 to 84% of MPN samples with non-mutated JAK2 and MPL corresponding to approximately 20%-30% of ET and PMF, but are generally absent in PV. Two main types of this mutation has been associate to MNP, a 52pb deletion (del 52, type I) (53%) and a 5bp insertion (ins5, type II) (32%). In a previous study with a knock-in model induced by viral plasmid for both Del52 and Ins5 showed that CALR mutants are able and sufficient to induce a thrombocytosis through MPL activation. Besides, CALR ins5 and del52 CALR displayed a different efficiency for the development of myelofibrosis, rapid for del52 and with no progression or very long latency for ins5. Thus, the retroviral mouse model mimicked the natural history of MPN patients and underlined the correlation between genotype and phenotype of the disease[7]. Therefore, the aim of this project is to evaluate the role of CALR mutation on hematopoesis. for that will be analyzed by flow cytometer the phenotypic characteristic (Lin- / Sca-1 + / c-kit + / CD150 + / CD48- ) of hematopoetic stem cells (HSC), analyzed by measuring blood and marrow parameters, perfomed clonogenic assays and carry out secondary or tertiary transplants. Moreover, analyzed signaling pathway by mass cytometer CyTOF (CEA, Fontenay-aux-Roses), and finally study if IFNa can also target cells carrying the mutation CALR focusing on HSC compartment and by which mechanism. (AU)