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Biochem Pharmacol. 2015 Oct 15;97(4):518-530. doi: 10.1016/j.bcp.2015.08.084. Epub 2015 Aug 8.

UBXN2A regulates nicotinic receptor degradation by modulating the E3 ligase activity of CHIP.

Author information

1
Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, United States.
2
Division of Basic Biomedical Sciences, Sanford School of Medicine, The University of South Dakota, Vermillion, SD 57069, United States.
3
Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, United States; Department of Psychiatry, 415 Curie Blvd., Clinical Research Building 219, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States. Electronic address: marielde@upenn.edu.

Abstract

Neuronal nicotinic acetylcholine receptors (nAChRs) containing the α3 subunit are known for their prominent role in normal ganglionic transmission while their involvement in the mechanisms underlying nicotine addiction and smoking-related disease has been emerging only in recent years. The amount of information available on the maturation and trafficking of α3-containing nAChRs is limited. We previously showed that UBXN2A is a p97 adaptor protein that facilitates the maturation and trafficking of α3-containing nAChRs. Further investigation of the mechanisms of UBXN2A actions revealed that the protein interacts with CHIP (carboxyl terminus of Hsc70 interacting protein), whose ubiquitin E3 ligase activity regulates the degradation of several disease-related proteins. We show that CHIP displays E3 ligase activity toward the α3 nAChR subunit and contributes to its ubiquitination and subsequent degradation. UBXN2A interferes with CHIP-mediated ubiquitination of α3 and protects the nicotinic receptor subunit from endoplasmic reticulum associated degradation (ERAD). UBXN2A also cross-talks with VCP/p97 and HSC70/HSP70 proteins in a complex where α3 is likely to be targeted by CHIP. Overall,we identify CHIP as an E3 ligase for α3 and UBXN2A as a protein that may efficiently regulate the stability of CHIP's client substrates.

KEYWORDS:

CHIP; Proteasomal degradation; UBX domain; UBXN2A; p97; α3 Nicotinic subunit

PMID:
26265139
DOI:
10.1016/j.bcp.2015.08.084
[Indexed for MEDLINE]

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