Identification and characterization of preclinical models of spliceosome mutant myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are the most common myeloid malignancies of the elderly, characterized by dysplasia and ineffective haematopoiesis. Approximately 25.000 new cases occurring in the EU annually and 30-40% of MDS patients eventually progress acute myeloid leukaemia (AML). The disease (MDS) is still considered to be understudied. However, recent studies using whole exome sequencing (WES) analysis have led to the discovery of recurrent somatic mutations in genes, such as SF3B1 and SRSF2 functioning in the subunit of the spliceosomal machinery in MDS patients. The evidence to date points to heterozygous mutations in the spliceosome machinery components and the mutations are often clustered in particular functional domains, indicating an altered gain-of-function, and underscoring patho-biological relevance. Spliceosomal mutations may lead to miss-splicing and ultimately decreased expression of intact tumor suppressor genes. We hypothesize, that SRSF2 and SF3B1 skew hematopoietic cell differentiation and promote transformation due to miss-splicing of transcripts. To address this, I stably transfected cytokine dependent TF-1 AML M6 cells with a cDNA of SRSF2 encoding either the wt or mutant (SRSF2P95L) gene. Accordingly, I selected clones of SRSF2P95L, growing in a cytokine independent manner, for further characterization to test the impact of the SRSF2P95L mutation on the oncogenic phenotype. As a complementary approach, I aimed to study the impact of the allele- specific inactivation of endogenous SF3B1K666N by using the CRISPR/Cas9 degron knock-in approach.Identification and characterization of preclinical models of spliceosome mutant myelodysplastic syndrome