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RACK1/TRAF2 regulation of modulator of apoptosis-1 (MOAP-1)
Jennifer Law1, Isabel Kwek1, Orysya Svystun1
1Department of Pediatrics, Faculty of Science, National University of Singapore, Singapore 117543, Singapore.
Abstract:
MOAP-1 is a pro-apoptotic tumor suppressor molecule with a growing set of known interacting partners. We have demonstrated that during death receptor-dependent apoptosis, MOAP-1 is recruited to TNF-R1 or TRAIL-R1, followed by RASSF1A and Bax association. MOAP-1/Bax association promotes Bax conformational change resulting in the translocation of Bax into the mitochondrial membrane, mitochondrial membrane insertion and dysregulation resulting in several hallmark events that execute apoptosis. Although a role in apoptosis is established, it is currently unknown how MOAP-1 is regulated and how it links to Bax to promote apoptosis. In this study, we demonstrate robust association with RACK1, a versatile scaffolding protein that responds to activation of protein kinase C. Furthermore, we can demonstrate that RACK1 functions to bring the E3 ligase, TRAF2, to MOAP-1 in order to undergo a K63-dependent ubiquitination. Furthermore, RACK1 associates with MOAP-1 via electrostatic associations similar to those observed between MOAP-1/RASSF1A and MOAP-1/TNF-R1. These events illustrate the complex nature of MOAP-1 regulation and characterizes the important role of the scaffolding protein, RACK1, in influencing MOAP-1 biology.
Insights
Regulator ofapoptosis molecule 1 (MOAP-1) interacts with scaffolding protein RACK1, which recruits TRAF2 for ubiquitination, revealing MOAP-1 regulation mechanisms crucial for apoptosis.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- MOAP-1 is a pro-apoptotic tumor suppressor.
- MOAP-1 interacts with death receptors and Bax to induce apoptosis.
- Regulation of MOAP-1 remains largely unknown.
Purpose of the Study:
- To investigate the regulation of MOAP-1.
- To identify proteins interacting with MOAP-1.
- To elucidate MOAP-1's role in apoptosis signaling.
Main Methods:
- Co-immunoprecipitation assays to detect protein interactions.
- Ubiquitination assays to assess protein modification.
- Analysis of protein-protein electrostatic interactions.
Main Results:
- MOAP-1 robustly associates with RACK1, a scaffolding protein.
- RACK1 recruits the E3 ligase TRAF2 to MOAP-1 for K63-dependent ubiquitination.
- RACK1 binds MOAP-1 via electrostatic interactions, similar to MOAP-1/RASSF1A and MOAP-1/TNF-R1 interactions.
Conclusions:
- RACK1 plays a critical role in regulating MOAP-1.
- RACK1 influences MOAP-1 ubiquitination and subsequent apoptosis.
- This study elucidates a novel regulatory pathway for MOAP-1 in apoptosis.
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