Molecular analysis and biological implications of STAT3 signal transduction

Het onderzoek beschreven in dit proefschrift betref de signaaltransductie van een specifiek soort eiwitten in normale en kwaadaardige cellen. Signaaltransducties een verzamelnaam voor de processen die er voor zorgen dat een signaal van buitenaf wordt herkend en vervolgens omgezet wordt in een specifieke set gebeurtenissen binnen in de cel. ... Zie; Samenvattin

Dissecting Clonal Heterogeneity in AML

Using targeted single-cell DNA sequencing approaches, two articles in Nature and Nature Communications have now firmly established that acute myeloid leukemia is a highly dynamic oligoclonal disease. Clonal evolution during disease progression and therapy occurs in both linear and branched trajectories, with a clear order of mutational events

CombiFlow:Flow cytometry-based identification and characterization of genetically and functionally distinct AML subclones

Summary: Many cancers, including leukemias, are dynamic oligoclonal diseases. Tools to identify and prospectively isolate genetically distinct clones for functional studies are needed. We describe our CombiFlow protocol, which is a combinatorial flow cytometry-based approach to identify and isolate such distinct clones. CombiFlow enables the visualization of clonal evolution during disease progression and the identification of potential relapse-inducing cells at minimal residual disease (MRD) time points. The protocol can be adapted to various research questions and allows functional studies on live sorted cell populations.For complete details on the use and execution of this protocol, please refer to de Boer et al. (2018)

Ser727-dependent transcriptional activation by association of p300 with STAT3 upon IL-6 stimulation

AbstractActivation of the signal transducer and activator of transcription 3 (STAT3) in response to interleukin-6 (IL-6) type cytokines involves both phosphorylation of Tyr705, which enables dimerization, nuclear translocation and DNA binding, as well as ser727 phosphorylation. Here, we describe that the 65 C-terminal amino acids of STAT3 can function as an independent transcription activation domain (TAD), particularly when a negative charge is introduced at position 727 by mutation of the serine residue into aspartate. The strong transcriptional activity of the C-terminal STAT3 Ser727Asp TAD is coupled to a constitutive association with the co-activator p300. In HepG2 cells, p300 associates with STAT3 upon IL-6 stimulation, and overexpression of p300 enhances the transcriptional activity of STAT3α, but not of STAT3β or STAT3 Ser727Ala. We conclude that Ser727 phosphorylation in the C-terminal region of STAT3 is required for transactivation by association with p300

Genetic and epigenetic alterations that drive leukemic stem cell self-renewal

Acute myeloid leukemia has emerged as a paradigm for the concept of the cancer stem cell. This hypothesis presumes that the disease is maintained by a rare population of leukemia-initiating stem cells which have acquired genetic or epigenetic changes. It is most likely that a single (epi)genetic event will not be sufficient to cause leukemia, but that a number of sequential events are required. Similar to normal hematopoietic stem cells, both intrinsic as well as extrinsic factors that arise from the bone marrow niche, provide essential cues that regulate cell fate decisions such as leukemic stem cell self-renewal and differentiation. In this chapter, we will review the genetic and epigenetic abnormalities that underlie the process of leukemic transformation, and will discuss which events potentially co-operate to induce leukemia

Constitutive Activation of STAT5A Promotes Human Hematopoietic Stem Cell Self-Renewal and Erythroid Differentiation

Activation of the transcription factor signal transducer and activator of transcription (STAT)5 is involved in various aspects of hematopoiesis, affecting cell proliferation, differentiation, and cell survival. Constitutive activation of STAT5 has also been associated with leukemic transformation. We overexpressed the constitutively active mutant STAT5A(1*6) in human cord blood CD34+ cells and evaluated the effects on the hematopoietic potential of stem cells in a variety of in vitro and in vivo systems. The observed phenotypic changes were correlated with differential gene expression patterns induced by STAT5A(1*6). Our data indicate that a persistent activation of STAT5A in human hematopoietic stem and progenitor cells results in their enhanced self-renewal and diverts differentiation to the erythroid lineage