2026-04-24 東京大学
図1 ミトコンドリア（緑）とメラノソーム（紫）が細胞内で近接している様子（上段）と、電子顕微鏡による接触部位の観察像（左下）。右下は、両オルガネラの接触を発光で検出する新技術 MiMSBiT の概念図。
＜関連情報＞
- https://www.t.u-tokyo.ac.jp/press/pr2026-04-24-001
- https://www.nature.com/articles/s41467-026-70282-w
STIM1-ミトフシン2の相互作用は、ミトコンドリアとメラノソームの接触を繋ぎ止め、メラノソームの成熟を促進する STIM1-Mitofusin2 interactions tether mitochondria and melanosome contacts that promote melanosome maturation
Isshin Shiiba,Yuto Ishikawa,Hijiri Oshio,Naoki Ito,Fuya Yamaguchi,Shun Nagashima,Hideya Ando,Keitaro Umezawa,Yuri Miura,Yuhei Araiso,Koki Nakamura,Yusuke Hirabayashi,Ryoko Inatome & Shigeru Yanagi
Nature Communications Published:06 March 2026
DOI:https://doi.org/10.1038/s41467-026-70282-w
Abstract
Mitochondria form contact sites with multiple organelles to coordinate diverse cellular processes. Melanosomes, lysosome-related organelles, undergo stepwise maturation to synthesize and store melanin, but how they interact with mitochondria remains unclear. Here we show that mitochondria–melanosome contacts dynamically increase during melanosome maturation and are mediated by STIM1–MFN2 interactions. Using a NanoBiT-based reporter system, MiMSBiT (Mitochondria–Melanosome contact reporter applying NanoBiT), to monitor reversible mitochondria–melanosome contacts in living cells, we demonstrate that STIM1 localizes to melanosomes and promotes their contact with mitochondrial MFN2. A transient decrease in melanosomal lumen calcium induces STIM1 clustering and enhances its association with MFN2. These contacts locally increase mitochondrial ATP availability, leading to melanosome lumen acidification via proton channel activation. This acidification facilitates PMEL fibrillation, a key step in melanosome maturation. Together, our findings reveal a mechanism by which mitochondria–melanosome contacts regulate melanosome maturation.
