Structural and clinical consequences of activation loop mutations in class III receptor tyrosine kinases

2018 ◽  
Vol 191 ◽  
pp. 123-134 ◽  
Author(s):  
Lillian R. Klug ◽  
Jason D. Kent ◽  
Michael C. Heinrich
Keyword(s):  
Tyrosine Kinases ◽  
Receptor Tyrosine Kinases ◽  
Activation Loop ◽  
Class Iii ◽  
Clinical Consequences

Casitas B-lineage lymphoma mutants activate AKT to induce transformation in cooperation with class III receptor tyrosine kinases

2013 ◽  
Vol 41 (3) ◽  
pp. 271-280.e4 ◽  
Author(s):  
Harald Polzer ◽  
Hanna Janke ◽  
Diana Schmid ◽  
Wolfgang Hiddemann ◽  
Karsten Spiekermann
Keyword(s):  
Tyrosine Kinases ◽  
Receptor Tyrosine Kinases ◽  
Class Iii ◽  
B Lineage

Tyrosine 842 Residue in the Activation Loop of FLT3-ITD Is Indespensible for Oncogenic Transformation

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 1561-1561
Author(s):  
Julhash U. Kazi ◽  
Lars Rönnstrand
Keyword(s):  
Tyrosine Kinases ◽  
Receptor Tyrosine Kinases ◽  
Conflicts Of Interest ◽  
Point Mutations ◽  
Cellular Transformation ◽  
Receptor Activation ◽  
Tumor Formation ◽  
Activation Loop ◽  
Tyrosine Residues

Abstract The receptor tyrosine kinase FLT3 is mutated in around 30% of acute myeloid leukemia patients. The so-called internal tandem duplication (ITD) mutation in the juxtamembrane domain is the most common type of mutation in FLT3. Other oncogenic mutations include point mutations in the kinase domain. One of the hallmark of receptor activation is phosphorylation on several tyrosine residues in the receptor. Oncogenic FLT3 mutants display constitutive activity leading to aberrant cell proliferation and survival. Phosphorylation on several critical tyrosine residues is known to be essential for FLT3 signaling. The tyrosine residue Y842, which is located in the activation loop of FLT3, and is well conserved in all receptor tyrosine kinases. It has been demonstrated that tyrosine phosphorylation of the activation loop is essential for the activity of some but not all receptor tyrosine kinases. In this report we show that phosphorylation on Y842 residue is dispensable for receptor activity and stability. However, Y842 plays critical roles in oncogenic FLT3-ITD mediated transformation. We have shown that a Y-to-F mutation (Y842F) results in reduced cell viability and proliferation. This mutation also led to dramatic decrease in in vitro colony formation in semi-solid medium. Furthermore, cells carrying the Y842F mutant of FLT3-ITD displayed significant delay in tumor formation in nude mice. Gene expression analysis, using microarrays, showed that mutation of Y842 causes suppression of anti-apoptotic genes. Finally, we showed that phosphorylated Y842 is a binding site for SHP2 and mutation of this site results in impaired activation of signaling through the RAS/ERK pathway. Collectively, our data suggest that Y842 in FLT3 plays an important role in FLT3-mediated RAS/ERK signaling and cellular transformation. Disclosures No relevant conflicts of interest to declare.

scholarly journals Class III Receptor Tyrosine Kinases in Acute Leukemia – Biological Functions and Modern Laboratory Analysis

2015 ◽  
Vol 10s3 ◽  
pp. BMI.S22433 ◽  
Author(s):  
Rimma Berenstein
Keyword(s):  
Tyrosine Kinases ◽  
Complex Disease ◽  
Receptor Tyrosine Kinases ◽  
Physiological Role ◽  
Leukemic Cells ◽  
World Health ◽  
Laboratory Diagnostics ◽  
Screening Methods ◽  
Class Iii ◽  
Short Period

Acute myeloid leukemia (AML) is a complex disease caused by deregulation of multiple signaling pathways. Mutations in class III receptor tyrosine kinases (RTKs) have been implicated in alteration of cell signals concerning the growth and differentiation of leukemic cells. Point mutations, insertions, or deletions of RTKs as well as chromosomal translocations induce constitutive activation of the receptor, leading to uncontrolled proliferation of undifferentiated myeloid blasts. Aberrations can occur in all domains of RTKs causing either the ligand-independent activation or mimicking the activated conformation. The World Health Organization recommended including RTK mutations in the AML classification since their detection in routine laboratory diagnostics is a major factor for prognostic stratification of patients. Polymerase chain reaction (PCR)–based methods are well-validated for the detection of fms-related tyrosine kinase 3 ( FLT3) mutations and can easily be applied for other RTKs. However, when methodological limitations are reached, accessory techniques can be applied. For a higher resolution and more quantitative approach compared to agarose gel electrophoresis, PCR fragments can be separated by capillary electrophoresis. Furthermore, high-resolution melting and denaturing high-pressure liquid chromatography are reliable presequencing screening methods that reduce the sample amount for Sanger sequencing. Because traditional DNA sequencing is time-consuming, next-generation sequencing (NGS) is an innovative modern possibility to analyze a high amount of samples simultaneously in a short period of time. At present, standardized procedures for NGS are not established, but when this barrier is resolved, it will provide a new platform for rapid and reliable laboratory diagnostic of RTK mutations in patients with AML. In this article, the biological and physiological role of RTK mutations in AML as well as possible laboratory methods for their detection will be reviewed.

scholarly journals Intrasteric Inhibition of ATP Binding Is Not Required To Prevent Unregulated Autophosphorylation or Signaling by the Insulin Receptor

2001 ◽  
Vol 21 (13) ◽  
pp. 4197-4207 ◽  
Author(s):  
Mark Frankel ◽  
Ararat J. Ablooglu ◽  
Joseph W. Leone ◽  
Elena Rusinova ◽  
J. B. Alexander Ross ◽  
...  
Keyword(s):  
Insulin Receptor ◽  
Conformational Changes ◽  
Tyrosine Kinases ◽  
Receptor Tyrosine Kinases ◽  
Kinase Domain ◽  
Atp Binding ◽  
Activation Loop ◽  
Wild Type ◽  
Solution Studies ◽  
Activated State

ABSTRACT Receptor tyrosine kinases may use intrasteric inhibition to suppress autophosphorylation prior to growth factor stimulation. To test this hypothesis we made an Asp1161Ala mutant in the activation loop that relieved intrasteric inhibition of the unphosphorylated insulin receptor (IR) and its recombinant cytoplasmic kinase domain (IRKD) without affecting the activated state. Solution studies with the unphosphorylated mutant IRKD demonstrated conformational changes and greater catalytic efficiency from a 10-fold increase ink cat and a 15-fold-lowerK m ATP althoughK m peptide was unchanged. Kinetic parameters of the autophosphorylated mutant and wild-type kinase domains were virtually identical. The Asp1161Ala mutation increased the rate of in vitro autophosphorylation of the IRKD or IR at low ATP concentrations and in the absence of insulin. However, saturation with ATP (for the IRKD) or the presence of insulin (for the IR) yielded equivalent rates of autophosphorylation for mutant versus wild-type kinases. Despite a biochemically more active kinase domain, the mutant IR expressed in C2C12 myoblasts was not constitutively autophosphorylated. However, it displayed a 2.5-fold-lower 50% effective concentration for insulin stimulation of autophosphorylation and was dephosphorylated more slowly following withdrawal of insulin than wild-type IR. In tests of the regulation of the unphosphorylated basal state, these results demonstrate that neither intrasteric inhibition against ATP binding nor suppression of kinase activity is required to prevent premature autophosphorylation of the IR. Finally, the lower rate of dephosphorylation suggests invariant residues of the activation loop such as Asp1161 may function at multiple junctures in cellular regulation of receptor tyrosine kinases.

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