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Cloning and characterization of a novel adaptor protein, CIN85, that interacts with c-Cbl
1Hematology Branch, National Institutes of Health, Bethesda, Maryland, 20892, USA.
Abstract:
The c-Cbl protooncogene product is a prominent substrate of protein tyrosine kinases and is rapidly tyrosine-phosphorylated upon stimulation of a wide variety of cell-surface receptors. We have identified a novel c-Cbl-interacting protein termed CIN85 with a molecular mass of 85 kDa which shows similarity to adaptor proteins, CMS and CD2AP. CIN85 mRNA is expressed ubiquitously in normal human tissues and cancer cell lines analyzed. CIN85 was basally associated with c-Cbl. For interaction of CIN85 with c-Cbl, the second SH3 domain of CIN85 was shown to serve as a central player. The CIN85-c-Cbl association was enhanced shortly after stimulation of 293 cells with epidermal growth factor (EGF) and gradually diminished to a basal level, which correlated with a tyrosine phosphorylation level of c-Cbl. Our results suggest that CIN85 may play a specific role in the EGF receptor-mediated signaling cascade via its interaction with c-Cbl.
Insights
Researchers discovered CIN85, a novel protein that interacts with c-Cbl. This interaction is crucial for epidermal growth factor (EGF) receptor signaling pathways.
Area of Science:
- Molecular and Cellular Biology
- Signal Transduction
- Oncogene Research
Background:
- The c-Cbl proto-oncogene product is a key substrate for protein tyrosine kinases.
- c-Cbl undergoes rapid tyrosine phosphorylation upon stimulation of various cell-surface receptors, indicating its role in signaling pathways.
Purpose of the Study:
- To identify novel proteins interacting with c-Cbl.
- To investigate the role of a newly identified c-Cbl-interacting protein, CIN85, in cellular signaling.
Main Methods:
- Identification and characterization of CIN85, an 85 kDa protein.
- Analysis of CIN85 mRNA expression in human tissues and cancer cell lines.
- Investigation of CIN85-c-Cbl interaction using biochemical assays, focusing on the role of CIN85's SH3 domains.
- Stimulation of 293 cells with epidermal growth factor (EGF) to study dynamic changes in CIN85-c-Cbl association and c-Cbl phosphorylation.
Main Results:
- A novel c-Cbl-interacting protein, CIN85, was identified, sharing similarities with adaptor proteins CMS and CD2AP.
- CIN85 mRNA is ubiquitously expressed in normal human tissues and cancer cell lines.
- CIN85 was found to be constitutively associated with c-Cbl, with the second SH3 domain of CIN85 being critical for this interaction.
- The association between CIN85 and c-Cbl was transiently enhanced upon EGF stimulation, correlating with c-Cbl tyrosine phosphorylation levels.
Conclusions:
- CIN85 is a novel adaptor protein that interacts with c-Cbl.
- The interaction between CIN85 and c-Cbl is regulated by EGF stimulation and c-Cbl phosphorylation.
- CIN85 likely plays a specific role in the epidermal growth factor receptor (EGFR) signaling cascade through its interaction with c-Cbl.