Identification of a Novel Mode of Kinase Inhibitor Resistance: An F604S Exchange in FIP1L1-PDGFRA Modulates FIP1L1-PDGFRA Protein Stability in a SRC-Dependent Manner

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 2792-2792
Author(s):  
Sivahari P. Gorantla ◽  
Nikolas von Bubnoff ◽  
Christian Peschel ◽  
Justus Duyster
Keyword(s):  
Protein Stability ◽  
Kinase Activity ◽  
Kinase Domain ◽  
Sh2 Domain ◽  
Drug Binding ◽  
Dependent Manner ◽  
Resistance Mutations ◽  
Cell Clones ◽  
Imatinib Resistant ◽  
Pdgfr Alpha

Abstract FIP1L1-PDGFR alpha is a constitutively activated protein kinase which was reported in chronic eosinophilic leukemia (CEL) and in cases of hypereosinophilic syndrome and mastocytosis with eosinophilia. Imatinib is clinically active against FIP1L1-PDGFRA positive disease. However, clinical resistance to imatinib has been observed in FIP1L1-PDGFRA positive leukemia and was shown to occur due to a secondary mutation (T674I) in the PDGFR alpha kinase domain. Using a screening strategy to identify imatinib resistant mutations, we generated numerous imatinib resistant cell clones. Analysis of the PDGFRA kinase domain in these cell clones revealed a broad spectrum of resistance mutations including the clinically reported exchange T674I. Interestingly, one of the abundant mutations was a Phe to Ser exchange at position 604 (F604S), which occurred alone or in combination with other exchanges. Surprisingly, FIP1L1-PDGFRA/F604S in contrast to D842H and F604+D842H did not increase the biochemical or cellular IC50 value to imatinib when compared to wild-type (wt). However, F604S and F604S+D842H transformed Ba/F3, NIH3T3 and mouse bone marrow more efficiently compared to wt and D842H, respectively. Also, F604S and F604S+D842H showed strong activation of Stat5, ERK and Akt compared to wt and D842H. Immunoprecipitation and immunoblotting indicated increased amounts of FIP1L1-PDGFRA protein in F604S versus wt cells. Moreover, SRC coimmunoprecipitated with FIP1L1-PDGFRA in wt, but not F604S cells. We hypothesized that F604S might interfere with FIP1L1-PDGFRA protein stability, and that SRC might be involved in this process. GST pull down experiments using SRC-SH2 domain showed lesser binding of FIP1L1-PDGFRA/F604S compared to wt. Similarly, using a GST-PDGFRA fragment, more SRC was precipitated with wt compared to F604S. Importantly both, the SRC inhibitor PD166326 and SRC siRNA mimicked the F604S phenotype and resulted in stabilization of the wt protein. Also, co-expression of SRC in 293T cells augmented degradation of wt, but not F604S FIP1L1-PDGFRA, indicating that SRC is a negative regulator of FIP1L1-PDGFRA protein stability. Similar results were obtained with an exchange in near proximity to F604. Kinase-defective SRC had no effect on FIP1L1-PDGFRA stability, indicating that kinase activity of SRC is necessary for its effect on FIP1L1-PDGFRA stability. Moreover, kinase defective FIP1L1-PDGFRA (G610R) was not degraded indicating that kinase activity of FIP1l1-PDGFRA is necessary for its own degradation. Taken together, imatinib resistance screening in FIP1L1-PDGFRA identified a novel class of resistance mutations, that do not act by impeding drug binding to the target, but rather increase target protein levels by interfering with its SRC mediated degradation.

Identification of a Novel Mode of Kinase Inhibitor Resistance: An F604S Exchange in FIP1L1-PDGFRA Modulates FIP1L1-PDGFRA Protein Stability in a SHP-2 and SRC-Dependent Manner

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1739-1739
Author(s):  
Sivahari Prasad Gorantla ◽  
Nikolas von Bubnoff ◽  
Christian Peschel ◽  
Justus Duyster
Keyword(s):  
Protein Stability ◽  
Kinase Domain ◽  
Drug Binding ◽  
Negative Regulator ◽  
Dependent Manner ◽  
Resistance Mutations ◽  
Imatinib Resistance ◽  
Cell Clones ◽  
Imatinib Resistant ◽  
Pdgfr Alpha

Abstract Abstract 1739 FIP1L1-PDGFR alpha is a constitutively activated protein kinase which was reported in chronic eosinophilic leukemia (CEL) and in cases of hypereosinophilic syndrome and mastocytosis with eosinophilia. Imatinib is clinically active against FIP1L1-PDGFRA positive disease. However, clinical resistance to imatinib has been observed in FIP1L1-PDGFRA positive leukemia and was shown to occur due to a secondary mutation (T674I) in the PDGFR alpha kinase domain. Using a screening strategy to identify imatinib resistant mutations, we generated numerous imatinib resistant cell clones. Analysis of the PDGFRA kinase domain in these cell clones revealed a broad spectrum of resistance mutations including the clinically reported exchange T674I. Interestingly, one of the abundant mutations was a Phe to Ser exchange at position 604 (F604S), which occurred alone or in combination with other exchanges. Surprisingly, FIP1L1-PDGFRA/F604S did not increase the biochemical or cellular IC50 value to imatinib when compared to wild-type (WT FP). However, F604S and F604S+D842H transformed Ba/F3 and mouse bone marrow more efficiently compared to WT and D842H, respectively. Immunoprecipitation and immunoblotting indicated increased amounts of FIP1L1-PDGFRA protein in F604S versus WT cells. Pulse chase analysis revealed that FIP1L1-PDGFRA/F604S is strongly stabilized compared to WT. SRC coimmunoprecipitated with FIP1L1-PDGFRA in WT, but not F604S cells. Co-expression of SRC in 293T cells augmented degradation of WT, but not F604S FIP1L1-PDGFRA, indicating that SRC is a negative regulator of FIP1L1-PDGFRA protein stability. Importantly both, the SRC inhibitor PD166326 and SRC siRNA mimicked the F604S phenotype and resulted in stabilization of the WT protein. Importantly, phosphatase inhibitor treatment of FIP1L1-PDGFRA/F604S led to destabilization and SRC recruitment indicating that phosphatases might be responsible for the enhanced stability of FIP1L1-PDGFRA/F604S. In fact, coimmunuprecipitaion experiments identified the phosphatase SHP2 as a specific binding partner of F604S and mapping experiments revealed that the phosphatase domain of SHP-2 directly interacted with FIP1L1-PDGFRA/F604S but not with wt- FIP1L1-PDGFRA. Together, these results suggest that stabilization of FIP1L1-PDGFRA/F604S is due to dephosphorylation by SHP-2 leading to lesser activation of the SRC and Cbl mediated ubiquitination machinery. Finally a novel exchange (L629P) identified in imatinib resistance CEL patient also leads to the stabilization of FIP1L1-PDGFRA protein similar to F604S. This indicates that stabilization of FIP1L1-PDGFRA is a common mode of drug resistance in FIP1L1-PDGFRA positive HES or CEL. In summary, imatinib resistance screening identified a novel class of resistance mutations in FIP1L1-PDGFRA, that do not act by impeding drug binding to the target, but increased target protein stability and abundance by interfering with SRC- mediated degradation. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Cumulative mechanism of several major imatinib-resistant mutations in Abl kinase

2020 ◽  
Vol 117 (32) ◽  
pp. 19221-19227 ◽  
Author(s):  
Marc Hoemberger ◽  
Warintra Pitsawong ◽  
Dorothee Kern
Keyword(s):  
Resistance Mechanisms ◽  
Kinase Domain ◽  
Drug Binding ◽  
Prolonged Treatment ◽  
Cancer Drug ◽  
Resistance Mutations ◽  
Imatinib Resistant ◽  
Order Of Magnitude ◽  
Patient Resistance ◽  
Emergence Of Resistance

Despite the outstanding success of the cancer drug imatinib, one obstacle in prolonged treatment is the emergence of resistance mutations within the kinase domain of its target, Abl. We noticed that many patient-resistance mutations occur in the dynamic hot spots recently identified to be responsible for imatinib’s high selectivity toward Abl. In this study, we provide an experimental analysis of the mechanism underlying drug resistance for three major resistance mutations (G250E, Y253F, and F317L). Our data settle controversies, revealing unexpected resistance mechanisms. The mutations alter the energy landscape of Abl in complex ways: increased kinase activity, altered affinity, and cooperativity for the substrates, and, surprisingly, only a modestly decreased imatinib affinity. Only under cellular adenosine triphosphate (ATP) concentrations, these changes cumulate in an order of magnitude increase in imatinib’s half-maximal inhibitory concentration (IC50). These results highlight the importance of characterizing energy landscapes of targets and its changes by drug binding and by resistance mutations developed by patients.

scholarly journals Mutation in Abl kinase with altered drug-binding kinetics indicates a novel mechanism of imatinib resistance

2021 ◽  
Vol 118 (46) ◽  
pp. e2111451118
Author(s):  
Agatha Lyczek ◽  
Benedict-Tilman Berger ◽  
Aziz M. Rangwala ◽  
YiTing Paung ◽  
Jessica Tom ◽  
...  
Keyword(s):  
Binding Site ◽  
Kinase Domain ◽  
Protein Kinase Inhibitors ◽  
Drug Binding ◽  
The Body ◽  
Binding Kinetics ◽  
Wild Type ◽  
Resistance Mutations ◽  
Imatinib Resistance ◽  
Abl Kinase

Protein kinase inhibitors are potent anticancer therapeutics. For example, the Bcr-Abl kinase inhibitor imatinib decreases mortality for chronic myeloid leukemia by 80%, but 22 to 41% of patients acquire resistance to imatinib. About 70% of relapsed patients harbor mutations in the Bcr-Abl kinase domain, where more than a hundred different mutations have been identified. Some mutations are located near the imatinib-binding site and cause resistance through altered interactions with the drug. However, many resistance mutations are located far from the drug-binding site, and it remains unclear how these mutations confer resistance. Additionally, earlier studies on small sets of patient-derived imatinib resistance mutations indicated that some of these mutant proteins were in fact sensitive to imatinib in cellular and biochemical studies. Here, we surveyed the resistance of 94 patient-derived Abl kinase domain mutations annotated as disease relevant or resistance causing using an engagement assay in live cells. We found that only two-thirds of mutations weaken imatinib affinity by more than twofold compared to Abl wild type. Surprisingly, one-third of mutations in the Abl kinase domain still remain sensitive to imatinib and bind with similar or higher affinity than wild type. Intriguingly, we identified three clinical Abl mutations that bind imatinib with wild type–like affinity but dissociate from imatinib considerably faster. Given the relevance of residence time for drug efficacy, mutations that alter binding kinetics could cause resistance in the nonequilibrium environment of the body where drug export and clearance play critical roles.

scholarly journals The common src homology region 2 domain of cytoplasmic signaling proteins is a positive effector of v-fps tyrosine kinase function.

1989 ◽  
Vol 9 (10) ◽  
pp. 4131-4140 ◽  
Author(s):  
C A Koch ◽  
M Moran ◽  
I Sadowski ◽  
T Pawson
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Kinases ◽  
Kinase Activity ◽  
Specific Activity ◽  
Intramolecular Interaction ◽  
Kinase Domain ◽  
Sh2 Domain ◽  
Homology Region ◽  
Src Homology ◽  
Type V

A conserved noncatalytic domain SH2 (for src homology region 2) is located immediately N terminal to the kinase domains of all cytoplasmic protein-tyrosine kinases. We found that the wild-type v-fps SH2 domain stimulated the enzymatic activity of the adjacent kinase domain 10-fold and functioned as a powerful positive effector of catalytic and transforming activities within the v-fps oncoprotein (P130gag-fps). Partial proteolysis of P130gag-fps and supporting genetic data indicated that the v-fps SH2 domain exerts its effect on catalytic activity through an intramolecular interaction with the kinase domain. Amino acid alterations in the SH2 domain that impaired kinase function interfered with association of the SH2 domain with the kinase domain. Deletion of a conserved octapeptide motif converted the v-fps SH2 domain from an activator to an inhibitor of tyrosine kinase activity. This latent inhibitory activity of v-fps SH2 has functional implications for phospholipase C-gamma and p21ras GTPase-activating protein, both of which have two distinct SH2 domains suggestive of complex regulation. In addition to regulating the specific activity of the kinase domain, the SH2 domain of P130gag-fps was also found to be required for the tyrosine phosphorylation of specific cellular proteins, notably polypeptides of 124 and 62 kilodaltons. The SH2 domain therefore appears to play a dual role in regulation of kinase activity and recognition of cellular substrates.

scholarly journals Landscape of drug-resistance mutations in kinase regulatory hotspots

2020 ◽  
Author(s):  
Pora Kim ◽  
Hanyang Li ◽  
Junmei Wang ◽  
Zhongming Zhao
Keyword(s):  
Drug Resistance ◽  
Large Scale ◽  
Kinase Inhibitors ◽  
Growth Factor Receptor ◽  
Kinase Domain ◽  
Systematic Investigation ◽  
Drug Binding ◽  
Data Sets ◽  
Resistance Mutations ◽  
Cancer Data

Abstract More than 48 kinase inhibitors (KIs) have been approved by Food and Drug Administration. However, drug-resistance (DR) eventually occurs, and secondary mutations have been found in the previously targeted primary-mutated cancer cells. Cancer and drug research communities recognize the importance of the kinase domain (KD) mutations for kinasopathies. So far, a systematic investigation of kinase mutations on DR hotspots has not been done yet. In this study, we systematically investigated four types of representative mutation hotspots (gatekeeper, G-loop, αC-helix and A-loop) associated with DR in 538 human protein kinases using large-scale cancer data sets (TCGA, ICGC, COSMIC and GDSC). Our results revealed 358 kinases harboring 3318 mutations that covered 702 drug resistance hotspot residues. Among them, 197 kinases had multiple genetic variants on each residue. We further computationally assessed and validated the epidermal growth factor receptor mutations on protein structure and drug-binding efficacy. This is the first study to provide a landscape view of DR-associated mutation hotspots in kinase’s secondary structures, and its knowledge will help the development of effective next-generation KIs for better precision medicine.

scholarly journals p90 ribosomal S6 kinase 2 is associated with and dephosphorylated by protein phosphatase 2Cδ

2004 ◽  
Vol 382 (2) ◽  
pp. 425-431 ◽  
Author(s):  
Ulrik DOEHN ◽  
Steen GAMMELTOFT ◽  
Shi-Hsiang SHEN ◽  
Claus J. JENSEN
Keyword(s):  
Protein Phosphatase ◽  
Kinase Activity ◽  
Kinase Domain ◽  
Protein Kinase Activity ◽  
Dependent Manner ◽  
S6 Kinase ◽  
Ribosomal S6 Kinase 2 ◽  
P90 Ribosomal S6 Kinase ◽  
Ribosomal S6 Kinase

RSK2 (p90 ribosomal S6 kinase 2) is activated via the ERK (extracellular-signal-regulated kinase) pathway by phosphorylation on four sites: Ser227 in the activation loop of the N-terminal kinase domain, Ser369 in the linker, Ser386 in the hydrophobic motif and Thr577 in the C-terminal kinase domain of RSK2. In the present study, we demonstrate that RSK2 is associated in vivo with PP2Cδ (protein phosphatase 2Cδ). In epidermal growth factorstimulated cells, RSK2 is partially dephosphorylated on all four sites in an Mn2+-dependent manner, leading to reduced protein kinase activity. Furthermore, PP2Cδ is phosphorylated by ERK on Thr315 and Thr333 in the catalytic domain. Mutation of Thr315 and Thr333 to alanine in a catalytically inactive mutant PP2Cδ(H154D) (His154→Asp) increases the association with RSK2 significantly, whereas mutation to glutamate, mimicking phosphorylation, reduces the binding of RSK2. The domains of interaction are mapped to the N-terminal extension comprising residues 1–71 of PP2Cδ and the N-terminal kinase domain of RSK2. The interaction is specific, since PP2Cδ associates with RSK1–RSK4, MSK1 (mitogen- and stress-activated kinase 1) and MSK2, but not with p70 S6 kinase or phosphoinositide-dependent kinase 1. We conclude that RSK2 is associated with PP2Cδ in vivo and is partially dephosphorylated by it, leading to reduced kinase activity.

The common src homology region 2 domain of cytoplasmic signaling proteins is a positive effector of v-fps tyrosine kinase function

1989 ◽  
Vol 9 (10) ◽  
pp. 4131-4140
Author(s):  
C A Koch ◽  
M Moran ◽  
I Sadowski ◽  
T Pawson
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Kinases ◽  
Kinase Activity ◽  
Specific Activity ◽  
Intramolecular Interaction ◽  
Kinase Domain ◽  
Sh2 Domain ◽  
Homology Region ◽  
Src Homology ◽  
Type V

A conserved noncatalytic domain SH2 (for src homology region 2) is located immediately N terminal to the kinase domains of all cytoplasmic protein-tyrosine kinases. We found that the wild-type v-fps SH2 domain stimulated the enzymatic activity of the adjacent kinase domain 10-fold and functioned as a powerful positive effector of catalytic and transforming activities within the v-fps oncoprotein (P130gag-fps). Partial proteolysis of P130gag-fps and supporting genetic data indicated that the v-fps SH2 domain exerts its effect on catalytic activity through an intramolecular interaction with the kinase domain. Amino acid alterations in the SH2 domain that impaired kinase function interfered with association of the SH2 domain with the kinase domain. Deletion of a conserved octapeptide motif converted the v-fps SH2 domain from an activator to an inhibitor of tyrosine kinase activity. This latent inhibitory activity of v-fps SH2 has functional implications for phospholipase C-gamma and p21ras GTPase-activating protein, both of which have two distinct SH2 domains suggestive of complex regulation. In addition to regulating the specific activity of the kinase domain, the SH2 domain of P130gag-fps was also found to be required for the tyrosine phosphorylation of specific cellular proteins, notably polypeptides of 124 and 62 kilodaltons. The SH2 domain therefore appears to play a dual role in regulation of kinase activity and recognition of cellular substrates.

The Efficacy of Histone Deacetylase Inhibitor, Vorinostat against BCR-ABL Positive Leukemia Cells Include ABL Kinase Domain Mutation in Monotherapy and in Combination with Dasatinib

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3194-3194
Author(s):  
Seiichi Okabe ◽  
Tetsuzo Tauchi ◽  
Shinya Kimura ◽  
Taira Maekawa ◽  
Kazuma Ohyashiki ◽  
...  
Keyword(s):  
Cell Lines ◽  
Kinase Domain ◽  
Dependent Manner ◽  
Abl Kinase ◽  
Imatinib Resistant ◽  
Kinase Domain Mutation ◽  
Ubiquitin Proteasome ◽  
Mutant Cells ◽  
Dose Dependent ◽  
Dasatinib Treatment

Abstract The development of imatinib are represented a major therapeutic advance in BCR-ABL positive diseases. However, a substantial number of patients are either primary refractory or acquire resistance to imatinib associated with ABL kinase domain mutation and this becomes a problematic in clinically. Histone acetylation and deacetylation is important for the accurate regulation of gene expression. Histone deacetylase (HDAC) inhibitors such as vorinostat (suberoylamide hydroxamic acid: SAHA) are the class of anticancer drugs currently in clinical trials for the treatment of hematological malignacies and solid tumors. Especially, vorinostat have shown efficacy in a wide range of cancers such as cutaneous T-cell lymphoma (CTCL). However, the molecular and functional consequences of vorinostat against BCR-ABL expressing cellswith Abl kinase mutation have not fully known. In this study, we investigated the vorinostat efficacy by using the murine Ba/F3 cell line which was transfected wild type (Wt) p210 BCR-ABL or imatinib resistant BCR-ABL mutants such as G250E, Q252H, Y253F, E255K, M294V, T315I, T315A, F317L, F317V, M351T and H396P. 48 hours treatment of vorinostat exhibits cell growth inhibition and proapoptotic activity murine Ba/F3 cells ectopically expressing wild type (Wt) p210 and imatinib resistant BCR-ABL mutants including T315I mutation in a dose dependent manner. IC50 of these cell lines are Wt(720nM), G250E(625nM), Q252H(220nM), Y253F(525nM), E255K(685nM), M294V(785nM), T315I(500nM), T315A(715nM), F317L(560nM), F317V(565nM), M351T(375nM) and H396P(485nM). Vorinostat is more effective in BCR-ABL mutant cells compared with Ba/F3 Wt BCR-ABL cells. We examined the intra cellular signaling by using these cell lines. We found that caspase 3, and poly (ADP-ribose) polymerase (PARP) were activated in a dose and a time dependent manner. Phosphorylation of Crk-L which is downstream target of BCRABL was reduced after vorinostat treatment. We also found the protein level of BCR-ABL was reduced after 48 hours vorinostat treatment in a dose dependent manner. BCR-ABL degradations in mutant cells were significantly enhanced compared with Ba/F3 Wt p210 BCR-ABL cells. Protein degradation of BCR-ABL was blocked by ubiquitin-proteasome inhibitor, Lactacystin suggested that this was involved ubiquitin-proteasome pathway. Dasatinib is a potent dual Src/BCR-ABL kinase inhibitor. Dasatinib is more than 100- fold more potent than imatinib against the ABL kinases and retains this low nanomolar inhibitory activity against the imatinib resistant mutations. Because dasatinib has shown efficacy against imatinib resistant BCR-ABL mutant, we investigated the efficacy between vorinostat and dasatinib by using these cell lines. We found that combination of vorinostat and dasatinib synergistically cell growth inhibition of Wt and BCR-ABL mutatants Ba/F3 cells in 48 hours treatment. Phosphorylation of Crk-L was reduced after vorinostat and dasatinib treatment in these cells. Caspase 3 and PARP activation were also synergistically increased after vorinostat and dasatinib treatment. Data from this study suggested that administration of the clinically available HDAC inhibitor vorinostat may be a powerful strategy against BCR-ABL mutant cells and enhance cytotoxic effects of dasatinib in those imatinib resistant BCR-ABL mutant cells and this approach warrants further examination in BCR-ABL related malignancies.

Structural Positioning of the SH2 Domain Is Critical for Bcr-Abl Kinase Activity, Signal Transduction and Oncogenic Transformation

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 569-569
Author(s):  
Oliver D. Hantschel ◽  
Florian Grebien ◽  
Ines Kaupe ◽  
Giulio Superti-Furga
Keyword(s):  
Signal Transduction ◽  
Catalytic Activity ◽  
Kinase Activity ◽  
Critical Factor ◽  
Kinase Domain ◽  
Sh2 Domain ◽  
Pharmacological Intervention ◽  
Single Point Mutation ◽  
Mouse Bone Marrow

Abstract We have recently shown that the SH2 domain stimulates c-Abl catalytic activity and substrate phosphorylation. This effect is exerted directly through the establishment of a tight SH2-kinase domain interface in the active conformation of c-Abl (Filippakopoulos et al. (2008) Cell, in press, scheduled to be published on September 5, 2008). Mutations in the SH2 domain that presumably disrupt this SH2-kinase domain interface, such as the Ile164Glu mutation, result in severe impairment of Abl catalytic activity. Thus, correct positioning of the SH2 and kinase domain modules appears to be critical for efficient activation of cytoplasmic tyrosine kinases. Here, we present data showing that the same structural coupling of the SH2 and kinase domain is also a critical factor for full activation of the oncogenic fusion kinase Bcr-Abl. A single point mutation in the SH2 domain (Ile164Glu) led to a dramatic reduction in Bcr-Abl in vitro tyrosine kinase activity and Bcr-Abl autophosphorylation, both on the activation loop (pTyr-412) and the SH2-kinase domain linker (pTyr-245). This resulted in a strong decrease in global cellular tyrosine phosphorylation, as well as decreased phosphorylation of critical downstream mediators of Bcr-Abl signaling. Both wildtype Bcr-Abl, as well as the Bcr-Abl Ile164Glu mutant were able to confer factor independent growth to Ba/F3- and UT-7 cell lines, although to a different extent. Detailed data on the properties of the Ile164Glu mutation in vitro, in imatinib inhibition assays, transformation assays and mouse bone marrow transplant models will be presented. We propose that the structural positioning of the SH2 domain is a crucial factor for constitutive activity, signal transduction and transforming capacity of Bcr-Abl. Besides oligomerization via the N-terminal coiled-coiled domain and loss of the auto-inhibitory N-terminal myristoyl group, the proper positioning of the SH2 domain appears to be another critical factor that is required for constitutive activation of Bcr- Abl, which is the prerequisite for its ability to induce chronic myeloid leukemia (CML). Inhibitors of the SH2-kinase domain interface of Bcr-Abl may comprise alternative or additional points of pharmacological intervention for the treatment of imatinib-sensitive or -resistant CML or Ph+ acute lymphocytic leukemia.

scholarly journals Membrane-mediated dimerization potentiates PIP5K lipid kinase activity

2021 ◽  
Author(s):  
Scott D Hansen ◽  
Albert A Lee ◽  
Jay T Groves
Keyword(s):  
Kinase Activity ◽  
Dynamic Range ◽  
Critical Role ◽  
Catalytic Efficiency ◽  
Receptor Activation ◽  
Kinase Domain ◽  
Dependent Manner ◽  
Stochastic Variation ◽  
Lipid Kinase ◽  
Broad Dynamic Range

The phosphatidylinositol 4-phosphate 5-kinase (PIP5K) family of lipid modifying enzymes generate the majority of phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) lipids found at the plasma membrane in eukaryotic cells. PI(4,5)P2 lipids serve a critical role in regulating receptor activation, ion channel gating, endocytosis, and actin nucleation. Here we describe how PIP5K activity is regulated by cooperative binding to PI(4,5)P2 lipids and membrane-mediated dimerization of the kinase domain. In contrast to constitutively dimeric phosphatidylinositol 5-phosphate 4-kinase (PIP4K, type II PIPK), solution PIP5K exists in a weak monomer-dimer equilibrium. PIP5K monomers can associate with PI(4,5)P2 containing membranes and dimerize in a protein density dependent manner. Although dispensable for PI(4,5)P2 binding and lipid kinase activity, dimerization enhances the catalytic efficiency of PIP5K through a mechanism consistent with allosteric regulation. Additionally, dimerization amplifies stochastic variation in the kinase reaction velocity and strengthens effects such as the recently described stochastic geometry sensing. Overall, the mechanism of PIP5K membrane binding creates a broad dynamic range of lipid kinase activities that are coupled to the density of PI(4,5)P2 and membrane bound kinase.

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