Quantitative proteomics identifies PTP1B as modulator of B cell antigen receptor signaling

Schwarz, Jennifer; Grundmann, Lorenz; Kokot, Thomas; Kläsener, Kathrin; Fotteler, Sandra; Medgyesi, Dávid; Köhn, Maja; Reth, Michael; Warscheid, Bettina

doi:10.26508/lsa.202101084

Cited by 7 publications

(6 citation statements)

References 83 publications

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“…PTP1B occupies a central position in oncogenic signaling. In the last decade, several substrates of this phosphatase have been validated [22–24]. However, additional substrates that mediate the oncogenic effects of PTP1B in different types of cancer remain to be determined.…”

Section: Resultsmentioning

confidence: 99%

A PTP1B-Cdk3 signaling axis promotes cell cycle progression of human glioblastoma cells through an Rb-E2F dependent pathway

Villamar-Cruz

Loza-Mejía

Vivar-Sierra

et al. 2022

Preprint

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Protein tyrosine phosphatase 1B (PTP1B) plays a key role in developing different types of cancer. However, the molecular mechanism underlying this effect is unclear. To identify possible molecular targets of PTP1B that mediate its positive role in tumorigenesis, we undertook a SILAC-based phosphoproteomic approach, which allowed us to identify the Cyclin-dependent kinase 3 (Cdk3) as a novel PTP1B substrate. Molecular docking studies revealed stable interactions between the PTP1B catalytic domain and Cdk3. In addition, we observed that PTP1B dephosphorylates Cdk3 at Tyrosine residue 15 and interacts with it in the nuclear envelope of HEK293-T cells and the nucleus and cytoplasm of human glioblastoma (GB) cells. Finally, we found that the pharmacological inhibition of PTP1B leads to a cell cycle progression delay with the diminished activity of Cdk3, the consequent hypophosphorylation of Rb, and the down-regulation of E2F and its target genes Cdk1, Cyclin A, and Cyclin E1. These data delineate a novel signaling pathway from PTP1B to Cdk3 required for efficient cell cycle progression in an Rb-E2F dependent manner in human GB cells and suggest new therapeutic strategies for treating these tumors.

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Section: Resultsmentioning

confidence: 99%

A PTP1B-Cdk3 signaling axis promotes cell cycle progression of human glioblastoma cells through an Rb-E2F dependent pathway

Villamar-Cruz

Loza-Mejía

Vivar-Sierra

et al. 2022

Preprint

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“…We repeated this experiment for another SH3 domain-containing protein, ARHGAP12, that has been identified in proteomics studies as a PTP1B interactor, but for which the binding site on PTP1B has not been determined. 14 Coimmunoprecipitation of this interactor was also dependent on the proline-rich region (Figure 5C). These results show that the proline-rich region is important for both Grb2 and ARHGAP12 binding to PTP1B in cells.…”

Section: Grb2 Binding Alters Ptp1b Activity Against Phosphopeptide Su...mentioning

confidence: 90%

“…Several recent proteomics studies have revealed a suite of protein interactors for the tyrosine phosphatase PTP1B. 14,15,39 The functional consequences of many of these non-substrate PTP1B interactions remain unknown. Indeed, very few proteins have been shown to directly regulate PTP1B activity.…”

Section: Discussionmentioning

confidence: 99%

“…12 Alternatively, these phosphatases may be regulated through intermolecular interactions directly with the catalytic domain or flexible regions. Indeed, PTP1B is known to engage in a host of protein-protein interactions, [13][14][15][16] not all of which are substrates, and some of these interactors may allosterically modulate catalytic activity.…”

Section: Introductionmentioning

confidence: 99%

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Allosteric regulation of the tyrosine phosphatase PTP1B by a protein-protein interaction

Chartier,

Woods,

et al. 2024

Preprint

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The rapid identification of protein-protein interactions has been significantly enabled by mass spectrometry (MS) proteomics-based methods, including affinity purification-MS, crosslinking-MS, and proximity-labeling proteomics. While these methods can reveal networks of interacting proteins, they cannot reveal how specific protein-protein interactions alter cell signaling or protein function. For instance, when two proteins interact, there can be emergent signaling processes driven purely by the individual activities of those proteins being co-localized. Alternatively, protein-protein interactions can allosterically regulate function, enhancing or suppressing activity in response to binding. In this work, we investigate the interaction between the tyrosine phosphatase PTP1B and the adaptor protein Grb2, which have been annotated as binding partners in a number of proteomics studies. This interaction has been postulated to co-localize PTP1B with its substrate IRS-1 by forming a ternary complex, thereby enhancing the dephosphorylation of IRS-1 to suppress insulin signaling. Here, we report that Grb2 binding to PTP1B also allosterically enhances PTP1B catalytic activity. We show that this interaction is dependent on the proline-rich region of PTP1B, which interacts with the C-terminal SH3 domain of Grb2. Using NMR spectroscopy and hydrogen-deuterium exchange mass spectrometry (HDX-MS) we show that Grb2 binding alters PTP1B structure and/or dynamics. Finally, we use MS proteomics to identify other interactors of the PTP1B proline-rich region that may also regulate PTP1B function similarly to Grb2. This work presents one of the first examples of a protein allosterically regulating the enzymatic activity of PTP1B and lays the foundation for discovering new mechanisms of PTP1B regulation in cell signaling.Significance StatementProtein-protein interactions are critical for cell signaling. The interaction between the phosphatase PTP1B and adaptor protein Grb2 co-localizes PTP1B with its substrates, thereby enhancing their dephosphorylation. We show that Grb2 binding also directly modulates PTP1B activity through an allosteric mechanism involving the proline-rich region of PTP1B. Our study reveals a novel mode of PTP1B regulation through a protein-protein interaction that is likely to be exploited by other cellular interactors of this important signaling enzyme.

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“…The germinal center-derived Burkitt lymphoma B cell line Ramos is a useful system for learning more about human B cell biology (23,35,36). These B cells have been frequently used for signal transduction studies (37) and their transcriptome, proteome, and surfacesome have been determined (38)(39)(40). Furthermore, with the CRISPR/Cas-9 technology, it is now straightforward to introduce mutations or gene KOs in this cell line.…”

Section: Discussionmentioning

confidence: 99%

Class-specific sensing of HIV-1 antigens by the B cell antigen receptor depends on the CH1 domain

Ortiz,

Anasti,

Pane

et al. 2023

Preprint

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SUMMARYHow different classes of the B cell antigen receptor (BCR) sense viral antigens used in vaccination protocols is poorly understood. Here we study antigen binding and sensing of Ramos B cells expressing BCRs of either the IgM or IgG1 class with a specificity for the CD4-binding-site of the envelope (Env) protein of the human immune deficiency virus-1 (HIV-1). We find that, in spite of their identical antigen binding site, the two BCR classes differ drastically from each other in that the IgM-BCR and IgG1-BCR bind preferentially to monovalent and polyvalent antigens, respectively. By generating an IgM/IgG1 chimeric BCR we found that the class-specific antigen-sensing behavior can be transferred with the CH1γ domain from the IgG1-BCR to the IgM-BCR. Our results indicate that the class-switching process not only results in the production of antibody classes with different effector functions but also alters the antigen sensing of secondary B lymphocytes. These findings suggest that antigen valency in existing vaccination protocols should be modified and altered between primary versus secondary (booster) immunization.

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Quantitative proteomics identifies PTP1B as modulator of B cell antigen receptor signaling

Cited by 7 publications

References 83 publications

A PTP1B-Cdk3 signaling axis promotes cell cycle progression of human glioblastoma cells through an Rb-E2F dependent pathway

A PTP1B-Cdk3 signaling axis promotes cell cycle progression of human glioblastoma cells through an Rb-E2F dependent pathway

Allosteric regulation of the tyrosine phosphatase PTP1B by a protein-protein interaction

Class-specific sensing of HIV-1 antigens by the B cell antigen receptor depends on the CH1 domain

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