A PTP1B-Cdk3 Signaling Axis Promotes Cell Cycle Progression of Human Glioblastoma Cells through an Rb-E2F Dependent
Olga Villamar-Cruz1,2, Marco Antonio Loza-Mejía3, Alonso Vivar-Sierra3
1Unidad de Investigación en Biomedicina (UBIMED), Facultad de Estudios Superiores-Iztacala, UNAM Tlalnepantla, Estado de México, Mexico.
Molecular and Cellular Biology
|November 28, 2023
Summary
Protein tyrosine phosphatase 1B (PTP1B) targets Cyclin-dependent kinase 3 (Cdk3) to drive cancer cell cycle progression. Inhibiting PTP1B halts cell division by deactivating Cdk3, offering a potential therapeutic strategy.
Area of Science:
- Oncology
- Molecular Biology
- Cell Biology
Background:
- Protein tyrosine phosphatase 1B (PTP1B) is implicated in cancer development, but its precise molecular targets and mechanisms remain largely unknown.
- Understanding PTP1B's role in tumorigenesis requires identifying its direct substrates and downstream signaling pathways.
Purpose of the Study:
- To identify novel molecular targets of PTP1B involved in cancer progression.
- To elucidate the functional relationship between PTP1B and its identified targets in human glioblastoma cells.
Main Methods:
- Utilized SILAC-based phosphoproteomics to discover PTP1B substrates.
- Performed substrate trapping, docking studies, in vitro dephosphorylation assays, and siRNA-mediated depletion.
- Investigated cell cycle progression, protein activity, and gene expression in response to PTP1B modulation and Cdk3 activity.
Main Results:
- Identified Cyclin-dependent kinase 3 (Cdk3) as a novel substrate of PTP1B, with direct interaction and dephosphorylation at tyrosine 15.
- Pharmacological inhibition or genetic depletion of PTP1B caused cell cycle arrest, reduced Cdk3 activity, hypophosphorylation of Retinoblastoma protein (Rb), and downregulation of E2F target genes.
- Expression of a constitutively active Cdk3 mutant rescued cell cycle progression and gene expression, bypassing the need for PTP1B.
Conclusions:
- Established a novel signaling pathway where PTP1B dephosphorylates and activates Cdk3.
- This PTP1B-Cdk3 axis is crucial for Rb-E2F-mediated cell cycle progression in human glioblastoma.
- Targeting PTP1B may represent a viable strategy for inhibiting glioblastoma proliferation.
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