LASP1 is a novel BCR-ABL substrate and a phosphorylation-dependent binding partner of CRKL in chronic myeloid leukemia

Abstract

Chronic myeloid leukemia (CML) is characterized by a genomic translocation generating a permanently active BCR-ABL oncogene with a complex pattern of atypically tyrosine-phosphorylated proteins that drive the malignant phenotype of CML. Recently, the LIM and SH3 domain protein 1 (LASP1) was identified as a component of a six gene signature that is strongly predictive for disease progression and relapse in CML patients. However, the underlying mechanisms why LASP1 expression correlates with dismal outcome remained unresolved.Here, we identified LASP1 as a novel and overexpressed direct substrate of BCR-ABL in CML. We demonstrate that LASP1 is specifically phosphorylated by BCR-ABL at tyrosine-171 in CML patients, which is abolished by tyrosine kinase inhibitor therapy. Further studies revealed that LASP1 phosphorylation results in an association with CRKL – another specific BCR-ABL substrate and bona fide biomarker for BCR-ABL activity. pLASP1-Y171 binds to non-phosphorylated CRKL at its SH2 domain. Accordingly, the BCR-ABL-mediated pathophysiological hyper-phosphorylation of LASP1 in CML disrupts normal regulation of CRKL and LASP1, which likely has implications on downstream BCR-ABL signaling. Collectively, our results suggest that LASP1 phosphorylation might serve as an additional candidate biomarker for assessment of BCR-ABL activity and provide a first step toward a molecular understanding of LASP1 function in CML.

Phosphorylation-Dependent Differences in CXCR4-LASP1-AKT1 Interaction between Breast Cancer and Chronic Myeloid Leukemia

“…The generation and purification of GST-LASP1 [3], His-LASP1 [15], and GST-CRKL [11] labeled proteins has been described in detail earlier.…”

“…In this regard, LASP1 has been identified as member of a six genes signature highly predictive for CML [9] and a role of LASP1-CXCR4 in CML progression is discussed [10]. In addition, the constitutively active tyrosine kinase leads to hyperphosphorylation of proteins like Crk-like protein (CRKL) and LASP1 [11].…”

Altered expression of metabolic pathways in CLL detected by unlabelled quantitative mass spectrometry analysis

“…This analysis identified several well‐known B cell‐associated proteins including BAX, BCAP31, BCLAF1, CD44, CD47, CD53, LYN, PPIB, PTPRCAP, PTPRC and SYK. We also identified other leukaemia associated proteins IKZF1 (Zhang et al , ), LASP1 (Frietsch et al , ) and ARHGEF12 (Dirse et al , ). We did not identify CD19, probably due to the location of the trypsin cut sites resulting in a low number of peptides available for identification; this is supported by the fact that Alsagaby et al () also lacked CD19 identification in their MS analysis of B‐CLL cells.…”

PF-114, a Novel Inhibitor of Bcr-Abl Chimeric Tyrosine Kinase, Attenuates Intracellular CrkL Phosphorylation and Kills Chronic Myeloid Leukemia Cells

“…Ресурс www.kinasource.co.uk [14] приводит пере-чень из 18 белков, фосфорилируемых химерной тирозин-киназой, среди которых каспаза 9, РНК-полимераза II, ДНК-зависимая протеинкиназа, протеинкиназа D и др. Требуется установить роль LASP1 (LIM and SH3 domain protein) -белка, ассоциированного с цитоскелетом и фосфорилируемого Bcr-Abl [15,16]. Интересна и воз-можность ингибирования аутофосфорилирования самой тирозинкиназы, показанная для иматиниба [17]: в этом случае прерываются разные Bcr-Abl-зависимые сиг-нальные пути.…”