Wellcome/Cancer Research UK Gurdon Institute, Cambridge CB2 1QN, United Kingdom.
Department of Genetics, University of Cambridge, Cambridge CB2 3EH, United Kingdom.
Proc Natl Acad Sci U S A. 2023 Aug 22;120(34):e2306073120. doi: 10.1073/pnas.2306073120. Epub 2023 Aug 14.
Mitochondria are dynamic organelles that undergo frequent remodeling to accommodate developmental needs. Here, we describe a striking organization of mitochondria into a large ball-like structure adjacent to the nucleus in premeiotic spermatocytes, which we term "mitoball". Mitoballs are transient structures that colocalize with the endoplasmic reticulum, Golgi bodies, and the fusome. We observed similar premeiotic mitochondrial clusters in a wide range of insect species, including mosquitos and cockroaches. Through a genetic screen, we identified that Milton, an adaptor protein that links mitochondria to microtubule-based motors, mediates mitoball formation. Flies lacking a 54 amino acid region in the C terminus of Milton completely lacked mitoballs, had swollen mitochondria in their spermatocytes, and showed reduced male fertility. We suggest that the premeiotic mitochondrial clustering is a conserved feature of insect spermatogenesis that supports sperm development.
线粒体是具有动态特征的细胞器，经常进行重塑以适应发育需求。在这里，我们描述了一种惊人的结构，即在减数分裂前期精母细胞中，线粒体形成一个靠近细胞核的大球状结构，我们称之为“线粒体球”。线粒体球是一种短暂的结构，与内质网、高尔基体和融合体共定位。我们在包括蚊子和蟑螂在内的多种昆虫物种中观察到了类似的减数分裂前期线粒体簇。通过遗传筛选，我们发现 Milton 是一种连接线粒体和基于微管的马达的衔接蛋白，介导线粒体球的形成。缺乏 Milton 蛋白 C 端 54 个氨基酸区域的果蝇完全缺乏线粒体球，其精母细胞中的线粒体肿胀，并表现出雄性生育力降低。我们认为，减数分裂前期的线粒体聚类是昆虫精子发生的一个保守特征，支持精子的发育。
