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Clec16a, Nrdp1, and USP8 Form a Ubiquitin-Dependent Tripartite Complex That Regulates beta-Cell Mitophagy
Journal article   Open access   Peer reviewed

Clec16a, Nrdp1, and USP8 Form a Ubiquitin-Dependent Tripartite Complex That Regulates beta-Cell Mitophagy

Gemma Pearson, Biaoxin Chai, Tracy Vozheiko, Xueying Liu, Malathi Kandarpa, Robert C. Piper and Scott A. Soleimanpour
Diabetes (New York, N.Y.), Vol.67(2), pp.265-277
02/01/2018
DOI: 10.2337/db17-0321
PMCID: PMC5780060
PMID: 29180353
url
https://europepmc.org/articles/pmc5780060View
Published (Version of record) Open Access

Abstract

Mitophagy is a cellular quality-control pathway, which is essential for elimination of unhealthy mitochondria. While mitophagy is critical to pancreatic beta-cell function, the posttranslational signals governing beta-cell mitochondrial turnover are unknown. Here, we report that ubiquitination is essential for the assembly of a mitophagy regulatory complex, comprised of the E3 ligase Nrdp1, the deubiquitinase enzyme USP8, and Clec16a, a mediator of beta-cell mitophagy with unclear function. We discover that the diabetes gene Clec16a encodes an E3 ligase, which promotes nondegradative ubiquitin conjugates to direct its mitophagy effectors and stabilize the Clec16a-Nrdp1-USP8 complex. Inhibition of the Clec16a pathway by the chemotherapeutic lenalidomide, a selective ubiquitin ligase inhibitor associated with new-onset diabetes, impairs beta-cell mitophagy, oxygen consumption, and insulin secretion. Indeed, patients treated with lenalidomide develop compromised beta-cell function. Moreover, the beta-cell Clec16a-Nrdp1-USP8 mitophagy complex is destabilized and dysfunctional after lenalidomide treatment as well as after glucolipotoxic stress. Thus, the Clec16a-Nrdp1-USP8 complex relies on ubiquitin signals to promote mitophagy and maintain mitochondrial quality control necessary for optimal beta-cell function.
Endocrinology & Metabolism Life Sciences & Biomedicine Science & Technology

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