title: Arginine 595 is duplicated in patients with acute leukemias carrying internal tandem duplications of FLT3 and modulates its transforming potential.
abstract: FLT3-internal tandem duplications (FLT3-ITDs) comprise a heterogeneous group of mutations in patients with acute leukemias that are prognostically important. To characterize the mechanism of transformation by FLT3-ITDs, we sequenced the juxtamembrane region (JM) of FLT3 from 284 patients with acute leukemias. The length of FLT3-ITDs varied from 2 to 42 amino acids (AAs) with a median of 17 AAs. The analysis of duplicated AAs showed that in the majority of patients, the duplications localize between AAs 591 to 599 (YVDFREYEY). Arginine 595 (R595) within this region is duplicated in 77% of patients. Single duplication of R595 in FLT3 conferred factor-independent growth to Ba/F3 cells and activated STAT5. Moreover, deletion or substitution of the duplicated R595 in 2 FLT3-ITD constructs as well as the deletion of wild-type R595 in FLT3-ITD substantially reduced the transforming potential and STAT5 activation, pointing to a critical role of the positive charge of R595 in stabilizing the active confirmation of FLT3-ITDs. Deletion of R595 in FLT3-WT nearly abrogated the ligand-dependent activation of FLT3-WT. Our data provide important insights into the molecular mechanism of transformation by FLT3-ITDs and show that duplication of R595 is important for the leukemic potential of FLT3-ITDs.
authors: Clinical Cooperative Group Leukemia, GSF (National Research Center for Environment and Health), Munich, Germany.
authors: Sridhar
authors: S
authors: Vempati
authors: Carola
authors: C
authors: Reindl
authors: Seshu Kumar
authors: SK
authors: Kaza
authors: Ruth
authors: R
authors: Kern
authors: Theodora
authors: T
authors: Malamoussi
authors: Martin
authors: M
authors: Dugas
authors: Gudrun
authors: G
authors: Mellert
authors: Susanne
authors: S
authors: Schnittger
authors: Wolfgang
authors: W
authors: Hiddemann
authors: Karsten
authors: K
authors: Spiekermann
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019943:Amino Acid Substitution; D001120:Arginine; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D005260:Female; D020440:Gene Duplication; D006801:Humans; D007938:Leukemia / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D016296:Mutagenesis; D017384:Sequence Deletion; D051941:fms-Like Tyrosine Kinase 3 / Q000235:genetics*
chemical_list: D001120:Arginine; C497970:FLT3 protein, human; D051941:fms-Like Tyrosine Kinase 3