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A RP-UFLC Assay for Protein Tyrosine Phosphatases: Focus on Protein Tyrosine Phosphatase Non-Receptor Type 2 (PTPN2)
Romain Duval1, Linh-Chi Bui1, Jérémy Berthelet1
1Université Paris Diderot, Sorbonne Paris Cité, Unité de Biologie Fonctionnelle et Adaptative, CNRS UMR 8251, 75013, Paris, France.
Abstract:
Protein tyrosine phosphatases (PTPs) are involved in numerous signaling pathways and dysfunctions of certain of these enzymes have been linked to several human diseases including cancer and autoimmune diseases. PTPN2 is a PTP mainly expressed in hematopoietic cells and involved in growth factor and JAK/STAT signaling pathways. Loss of function analyses in patients with mutation/deletion of the PTPN2 gene and knock-out mouse models indicate that PTPN2 acts as a tumor suppressor in T-cell malignancies and as a regulator of inflammation and immunity. The use of sensitive and quantitative assays is of prime importance to better characterize the biochemical properties of PTPN2 and its biological roles. We report a highly sensitive non-radioactive assay that allows the measurement of the activity of purified PTPN2 and of endogenous PTPN2 immunoprecipitated on agarose beads. The assay relies on separation and quantitation by reverse-phase ultra fast liquid chromatography (RP-UFLC) of a fluorescein-labeled phosphotyrosine peptide substrate derived from the sequence of STAT1. The applicability and reliability of this approach is supported by kinetic and mechanistic studies using PTP inhibitors. More broadly, our PTPN2 assay provides the basis for the design of flexible methods for the measurement of other PTPs.
Insights
A new assay measures Protein Tyrosine Phosphatase Non-Receptor Type 2 (PTPN2) activity. This sensitive method aids in understanding PTPN2
Area of Science:
- Biochemistry
- Molecular Biology
- Enzymology
Background:
- Protein tyrosine phosphatases (PTPs) regulate critical signaling pathways.
- PTPN2, a key PTP in hematopoietic cells, is implicated in cancer, inflammation, and immunity.
- Dysfunctional PTPN2 is linked to human diseases, necessitating precise activity measurement.
Purpose of the Study:
- To develop a highly sensitive, non-radioactive assay for measuring PTPN2 enzyme activity.
- To characterize the biochemical properties and biological roles of PTPN2.
- To establish a reliable method for assessing endogenous PTPN2 activity.
Main Methods:
- Utilized a fluorescein-labeled phosphotyrosine peptide substrate derived from STAT1.
- Employed reverse-phase ultra-fast liquid chromatography (RP-UFLC) for separation and quantitation.
- Validated the assay using purified and immunoprecipitated PTPN2, alongside PTP inhibitors.
Main Results:
- Developed a sensitive assay for PTPN2 activity measurement in purified and endogenous forms.
- Demonstrated the assay's reliability through kinetic and mechanistic studies.
- Confirmed PTPN2's role as a tumor suppressor and immune regulator.
Conclusions:
- The novel assay enables accurate quantification of PTPN2 activity.
- This method facilitates deeper understanding of PTPN2's role in disease.
- The assay design is adaptable for measuring other PTP family members.
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