Rapid turnover of mitochondrial uncoupling protein 3.
Rapid turnover of mitochondrial uncoupling protein 3.
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DOI：
10.1042/bj20091321
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发表时间：
2010-01-27
期刊：
影响因子：
--
通讯作者：
Brand MD
中科院分区：
文献类型：
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作者：
Azzu V;Mookerjee SA;Brand MD
UCP3（解偶联蛋白 3）及其同源物 UCP2 和 UCP1 是线粒体功能的调节因子。众所周知，UCP2 的半衰期很短，约为 100 倍。 1 小时，这是由于其被胞质 26S 蛋白酶体快速降解，而 UCP1 通过线粒体自噬的速度要慢得多。在本研究中，我们研究了 UCP3 是否也具有短半衰期，以及蛋白酶体是否参与 UCP3 降解。通过用放线菌酮抑制蛋白质合成并通过免疫印迹分析监测 UCP3 蛋白质水平，检查了小鼠 C2C12 成肌细胞系中 UCP3 的半衰期。我们发现 UCP3 的半衰期很短，为 0.5-4 小时。蛋白酶体抑制剂混合物可防止快速降解，支持蛋白酶体周转机制。此外，这种表型在体外得到重现：UCP3 在从大鼠骨骼肌或棕色脂肪组织中分离的线粒体中被降解，半衰期为 0.5-4 小时，但仅在纯化的 26S 蛋白酶体组分存在的情况下。这种体外蛋白水解作用对蛋白酶体抑制也敏感。这种表型与半衰期较长的相关蛋白 UCP1 和腺嘌呤核苷酸转位酶形成鲜明对比。因此，UCP3 以蛋白酶体依赖性方式在多种细胞类型中快速更新。
UCP3 (uncoupling protein 3) and its homologues UCP2 and UCP1 are regulators of mitochondrial function. UCP2 is known to have a short half-life of approx. 1 h, owing to its rapid degradation by the cytosolic 26S proteasome, whereas UCP1 is turned over much more slowly by mitochondrial autophagy. In the present study we investigate whether UCP3 also has a short half-life, and whether the proteasome is involved inUCP3 degradation. UCP3 half-life was examined in the mouse C2C12 myoblast cell line by inhibiting protein synthesis with cycloheximide and monitoring UCP3 protein levels by immunoblot analysis. We show that UCP3 has a short half-life of 0.5–4 h. Rapid degradation was prevented by a cocktail of proteasome inhibitors, supporting a proteasomal mechanism for turnover. In addition, this phenotype is recapitulated in vitro: UCP3 was degraded in mitochondria isolated from rat skeletal muscle or brown adipose tissue with a half-life of 0.5–4 h, but only in the presence of a purified 26S proteasomal fraction. This in vitro proteolysis was also sensitive to proteasome inhibition. This phenotype is in direct contrast with the related proteins UCP1 and the adenine nucleotide translocase, which have long half-lives. Therefore UCP3 is turned over rapidly in multiple cell types in a proteasome-dependent manner.