Activity of the Bcr GTPase-activating Domain Is Regulated through Direct Protein/Protein Interaction with the Rho Guanine Nucleotide Dissociation Inhibitor

Kweon, Soo-Mi; Cho, Young Jin; Minoo, Parviz; Groffen, John; Heisterkamp, Nora

doi:10.1074/jbc.m705513200

Cited by 13 publications

(21 citation statements)

References 36 publications

(28 reference statements)

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“…Previously, BCR GAP activity was reported to be regulated by direct protein/protein interactions with the Rho guanine nucleotide dissociation inhibitor (Kweon et al, 2008). In the present work, an intramolecular interaction between the N-and C-termini of BCR was enhanced upon dephosphorylation by PTPRT and as a result, we found that BCR GAP activity seemed to be inhibited.…”

Section: Bcr Is a Key Factor In Neuronal Developmentsupporting

confidence: 51%

Regulation of dendritic arborization by BCR Rac1 GTPase-activating protein, a new substrate of protein tyrosine phosphatase receptor T

Park

Lim

et al. 2012

Journal of Cell Science

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SummaryDendritic arborization is important for neuronal development as well as the formation of neural circuits. Rac1 is a member of the Rho GTPase family that serve as regulators of neuronal development. Breakpoint cluster region protein (BCR) is a Rac1 GTPase-activating protein that is abundantly expressed in the central nervous system. Here, we show that BCR plays a key role in neuronal development. Dendritic arborization and actin polymerization were attenuated by overexpression of BCR in hippocampal neurons. Knockdown of BCR using specific shRNAs increased the dendritic arborization as well as actin polymerization. The number of dendrites in null mutant BCR 2/2 mice was considerably increased compared with that in wild-type mice. We found that the function of the BCR GTPaseactivating domain could be modulated by protein tyrosine phosphatase receptor T (PTPRT), which is expressed principally in the brain. We demonstrate that tyrosine 177 of BCR was the main target of PTPRT and the BCR mutant mimicking dephosphorylation of tyrosine 177 alleviated the attenuation of dendritic arborization. Additionally the attenuated dendritic arborization found upon BCR overexpression was relieved upon co-expression of PTPRT. When PTPRT was knocked down by a specific shRNA, the dendritic arborization was significantly reduced. The activity of the BCR GTPase-activating domain was modulated by means of conversions between the intra-and inter-molecular interactions, which are finely regulated through the dephosphorylation of a specific tyrosine residue by PTPRT. We thus show conclusively that BCR is a novel substrate of PTPRT and that BCR is involved in the regulation of neuronal development via control of the BCR GTPase-activating domain function by PTPRT.

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Section: Bcr Is a Key Factor In Neuronal Developmentsupporting

confidence: 51%

Regulation of dendritic arborization by BCR Rac1 GTPase-activating protein, a new substrate of protein tyrosine phosphatase receptor T

Park

Lim

et al. 2012

Journal of Cell Science

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“…Ligation of 5Ј SalI-StuI ϩ NaeI-SalI into pSK digested with SalI was followed by isolation of clones in the right orientation, to allow removal of the insert as 5Ј XbaI-3Ј KpnI fragment and ligation into pCDE ϫ XbaI ϫ KpnI. The Xpress-tagged BcrGAP, EGFPBcr, GST fusion BcrGAP, GST fusion AbrGAP, Xpress-tagged Bcr wild type, and Xpress-tagged BcrR1090A mutants have been described previously (8,19). TG2 was also subcloned by PCR into pProEx/HTa for purification of recombinant His 6 -tagged TG2.…”

Section: Methodsmentioning

confidence: 99%

“…GST Pull-down Assay-All procedures were done as described previously (19) with minor modifications. Recombinant GST fusion proteins were purified from Escherichia coli as described previously (23).…”

Section: Methodsmentioning

confidence: 99%

“…Transfection, Immunoprecipitation, and Western Blot AnalysisAll procedures were performed as described previously (19) with some modifications. All transfections were to COS-1 cells unless otherwise indicated.…”

Section: Methodsmentioning

confidence: 99%

“…The Bcr protein contains multiple domains that could be involved in regulation of the GAP activity. We recently identified a direct interaction with RhoGDI as one regulatory mechanism (19). However, it is likely that Bcr is regulated though multiple, different interactions.…”

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confidence: 99%

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Transglutaminase 2 Regulates the GTPase-activating Activity of Bcr

Groffen

Heisterkamp

2009

Journal of Biological Chemistry

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Transglutaminase 2 (TG2) is a multifunctional protein that has been implicated in numerous pathologies including that of neurodegeneration and celiac disease, but the molecular interactions that mediate its diverse activities are largely unknown. Bcr and the closely related Abr negatively regulate the small G-protein Rac: loss of their combined function in vivo results in increased reactivity of innate immune cells. Bcr and Abr are GTPase-activating proteins that catalyze the hydrolysis of the GTP bound to Rac. However, how the Bcr and Abr GTPaseactivating activity is regulated is not precisely understood. We here report a novel mechanism of regulation through direct protein-protein interaction with TG2. TG2 bound to the Rac-binding pocket in the GTPase-activating domains of Bcr and Abr, blocked Bcr activity and, through this mechanism, increased levels of active GTP-bound Rac and EGF-stimulated membrane ruffling. TG2 exists in at least two different conformations. Interestingly, experiments using TG2 mutants showed that Bcr exhibits preferential binding to the non-compacted conformation of TG2, in which its catalytic domain is exposed, but transamidation is not needed for the interaction. Thus, TG2 regulates levels of cellular GTP-bound Rac and actin cytoskeletal reorganization through a new mechanism involving direct inhibition of Bcr GTPase-activating activity.

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TPEN/TPGS (T2) combo dramatically reduces Philadelphia chromosome-positive pro-lymphoblastic B leukemia in BALB/c mice

2022

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Acute lymphoblastic leukemia (ALL) is hematological neoplasia that affects human beings from early life to adulthood. Although ALL treatment has been effective, an important percentage of ALL patients are resilient to treatment. Therefore, there is an urgent need for testing a new combination of compounds for the treatment of this disease. Recently, combined TPEN and TPGS (T2 combo) have shown selective cytotoxic effects in vitro leukemia cells such as Jurkat, K562, and Ba/F3 cells. In this study, we aimed to test the effect of combined TPEN and TPGS agents (T2 combo) at a fixed dose (TPEN 5 mg/kg: TPGS 100 mg/kg) on leukemic Ba/F3-BCR-ABL P210 BALB-c mice model. We found that 4 successive 2-day apart intravenous injections of T2 combo showed a statistically significant reduction of Ba/F3 BCR-ABL leukemia cells (− 69%) in leukemia BALB/c mice (n = 6) compared to untreated leukemia group (n = 6). Moreover, the T2 combo was innocuous to non-leukemia BALB/c mice (n = 3) compared to untreated non-leukemia mice (control, n = 3). After treatments (day 42), all mice were left to rest until day 50. Outstandingly, the leukemia BALB/c mice treated with the T2 combo showed a lower percentage of Ba/F3-BCR-ABL P210 cells (− 84%) than untreated leukemia BALB/c mice. Furthermore, treatment of leukemia and non-leukemia mice with T2 combo showed no significant tissue alteration/damage according to the histopathological analysis of brain, heart, liver, kidney, and spleen samples; however, T2 combo significantly reduced the number of leukocytes in the bone marrow of treated leukemia mice. We conclude that the T2 combo specifically affects leukemia cells but no other tissue/organs. Therefore, we anticipate that the T2 combo might be a potential pro-oxidant combination for the treatment of leukemia patients.

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Activity of the Bcr GTPase-activating Domain Is Regulated through Direct Protein/Protein Interaction with the Rho Guanine Nucleotide Dissociation Inhibitor

Cited by 13 publications

References 36 publications

Regulation of dendritic arborization by BCR Rac1 GTPase-activating protein, a new substrate of protein tyrosine phosphatase receptor T

Regulation of dendritic arborization by BCR Rac1 GTPase-activating protein, a new substrate of protein tyrosine phosphatase receptor T

Transglutaminase 2 Regulates the GTPase-activating Activity of Bcr

TPEN/TPGS (T2) combo dramatically reduces Philadelphia chromosome-positive pro-lymphoblastic B leukemia in BALB/c mice

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