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Oligopeptide Competition Assay for Phosphorylation Site Determination
Published on: May 18, 2017
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Phosphorylation of OTUB1 at Tyr 26 stabilizes the mTORC1 component, Raptor
Seung Un Seo1, Seon Min Woo1, Min Wook Kim2
1Department of Immunology, School of Medicine, Keimyung University, Daegu, 42601, South Korea.
Cell Death and Differentiation
|August 4, 2022
Summary
The study reveals OTUB1 stabilizes Raptor, a key protein in mTORC1 signaling, through phosphorylation. Targeting OTUB1 phosphorylation could offer a new strategy against cancer drug resistance by down-regulating Raptor.
Area of Science:
- Biochemistry
- Molecular Biology
- Oncology
Background:
- Raptor is crucial for mTORC1 signaling and its high expression confers resistance to PI3K/mTOR inhibitors in cancer.
- Understanding Raptor regulation is vital for developing effective cancer therapies.
Purpose of the Study:
- To elucidate the mechanism by which OTUB1 stabilizes Raptor.
- To investigate the role of OTUB1 phosphorylation in cancer cell response to anti-cancer drugs.
Main Methods:
- Biochemical assays to determine the interaction between OTUB1 and Raptor.
- Kinase assays to identify kinases phosphorylating OTUB1.
- Analysis of phospho-OTUB1 and Raptor levels in patient samples.
Main Results:
- OTUB1 stabilizes Raptor via a non-canonical mechanism involving tyrosine 26 (Y26) phosphorylation.
- Non-receptor tyrosine kinases (Src, SRMS) phosphorylate OTUB1 at Y26, stabilizing Raptor.
- Dephosphorylation of OTUB1 destabilizes Raptor, sensitizing cancer cells to drugs through mitochondrial dysfunction.
- Elevated phospho-OTUB1 and Raptor levels were observed in renal clear cell carcinoma patients.
Conclusions:
- OTUB1-mediated phosphorylation of Raptor is a novel regulatory pathway.
- Targeting OTUB1 phosphorylation presents a potential therapeutic strategy for overcoming cancer drug resistance.
- This pathway's dysregulation is implicated in renal clear cell carcinoma.
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