In situ architecture of the intercellular organelle reservoir between epididymal epithelial cells by volume electron microscopy

作者：Xia Li, Feng Qiao, Jiansheng Guo, Ting Jiang, Huifang Lou, Huixia Li, Gangcai Xie, Hangjun Wu, Weizhen Wang, Ruoyu Pei, Sha Liu, Mei Ye, Li Jin, Shiqin Huang, Mengya Zhang, Chaoye Ma, Yi‐Wen Huang, Shushu Xu, Xiaofeng Li, Xiao Sun, Jun Yu, Kin Lam Fok, Shumin Duan, Hao Chen · 发表于：Nature Communications · 年份：2025 · DOI：10.1038/s41467-025-56807-9 · 被引用次数：10 · 研究领域：Extracellular vesicles in disease、Barrier Structure and Function Studies、Lipid Membrane Structure and Behavior

Mammalian epididymal epithelial cells are crucial for sperm maturation. Historically, vacuole-like ultrastructures in epididymal epithelial cells were observed via transmission electron microscopy but were undefined. Here, we utilize volume electron microscopy (vEM) to generate 3D reconstructions of epididymal epithelial cells and identify these vacuoles as intercellular organelle reservoirs (IORs) in the lateral intercellular space (LIS), which contains protein aggregates, autophagosomes, lysosome-related organelles and mitochondrial residues. Immunolabelling of organelle markers such as P62, LC3, LAMP1 and TOMM20 confirm these findings. The IOR size or number varies across four epididymal regions and decreases with age. Rab27a mutant mice exhibit reduced IORs in the caput epididymis and a subfertility phenotype, suggesting the involvement of Rab27a in the formation of IORs. Furthermore, we observe the presence of IORs between intestinal epithelial cells besides epididymis. Amino acid transporters at IOR edges suggest dynamic protein recycling. Our findings reveal that the IOR is an important structure critical for organelle turnover and recycling outside epithelial cells with limited self-degradation capabilities.