Protein-tyrosine Phosphatase DEP-1 Controls Receptor Tyrosine Kinase FLT3 Signaling

Abstract

Phosphorylation of wild type FLT3 and AML-associated mutant FLT3 was recently analyzed using site-specific phosphotyrosine antibodies (15). Interestingly, the phosphorylation pattern of the different FLT3 variants showed quantitative and also qualitative differences. Although FLT3-ITD or mutations in the kinase domain resulted in ligand-independent FLT3 autophosphorylation and signaling activity, the wild type receptor is only autophosphorylated in response to stimulation with its cytokine FL.Signaling of receptor tyrosine kinases is modulated by protein-tyrosine phosphatases (PTP) (16), and aberrations in PTP function play a role in carcinogenesis (17). Some PTP, notably SHP-2, have been found to positively influence growth-stimulatory signaling pathways, and mutations leading to gain-offunction of these PTP can potentially be oncogenic. It has been demonstrated that SHP-2 directly interacts with FLT3 in a phosphorylation-dependent manner via phosphotyrosine 599. Table S1. 1 To whom correspondence should be addressed. Tel.: 49-3641-9395634; Fax:49-3641-9395602; E-mail: joerg.mueller2@med.uni-jena.de.2 The abbreviations used are: AML, acute myeloid leukemia; PTP, proteintyrosine phosphatase; FL, FLT3 ligand; PLC␥, phospholipase C␥; ITD, internal tandem duplication; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide.

NOX-driven ROS formation in cell transformation of FLT3-ITD-positive AML

“…The transmembrane PTP PTPRJ (also known as DEP-1, and CD148) was previously identified as bona fide PTP negatively regulating FLT3 receptor signaling in myeloid cells [69]. DEP-1 regulates FL ligand-induced FLT3 receptor signaling by associating with [70] and dephosphorylating FLT3 directly, thereby attenuating the activation of FLT3.…”

Cell transformation by FLT3 ITD in acute myeloid leukemia involves oxidative inactivation of the tumor suppressor protein-tyrosine phosphatase DEP-1/ PTPRJ

“…32D mouse hematopoietic progenitor cells stably expressing murine FLT3-WT or FLT3 ITD were a kind gift of Dr J. Duyster (Technical University of Munich, Munich, Germany) and were maintained in HEPES (N-2-hydroxyethylpiperazine-NЈ-2-ethanesulfonic acid)-buffered RPMI-1640 (Biochrom) with 10% heat-inactivated FBS, 1mM sodium pyruvate, and 2.5 ng/mL murine recombinant IL3 (Peprotech). 32D cells expressing human WT FLT3 or FLT3 ITD were previously described, 20 and were used for FLT3 autophosphorylation experiments.…”

“…Among several potentially relevant PTPs, we validated and characterized density-enhanced phosphatase-1 (DEP-1, systematic name PTPRJ, also CD148) as a negative regulator of WT FLT3 autophosphorylation and signaling. 20 In this study the role of DEP-1 for regulation of FLT3 ITD, the AML-related mutant version of FLT3 was explored. The experiments revealed that DEP-1 was expressed but not functioning as a PTP for FLT3 ITD.…”

“…Among several potentially relevant PTPs, we validated and characterized density-enhanced phosphatase-1 (DEP-1, systematic name PTPRJ, also CD148) as a negative regulator of WT FLT3 autophosphorylation and signaling. 20 Submitted February 11, 2011; accepted March 11, 2012. Prepublished online as Blood First Edition paper, March 20, 2012; DOI 10.1182 DOI 10.…”

Features of Ras activation by a mislocalized oncogenic tyrosine kinase: FLT3 ITD signals via K-Ras at the plasma membrane of Acute Myeloid Leukemia cells

“…Preparation of lentiviral particles and transduction of MV4-11 cells with constructs encoding EYFP-K-Ras or EYFP-K-RasS17N in the vector or control transductions with LeGO-iV were performed as described previously (Arora et al, 2011). Transduced cell pools were analyzed for cell proliferation using a Click-iT DNA synthesis kit (Alexa-Fluor-647-labeled C10419, Life Technologies, Darmstadt, Germany), or for apoptosis using an Annexin V-PE Kit (559763, BD Pharmingen, Heidelberg, Germany) with a FACSCanto flow cytometer (BD Biosciences, Heidelberg, Germany).…”