Retromer vesicles interact with RNA granules in haploid male germ cells

•VPS26A/VPS35-positive retromer vesicles are found in meiotic and postmeiotic cells.•Chromatoid body is closely associated with ER and surrounded by vesicles and MVBs.•Retromer vesicles interact with chromatoid bodies in round spermatids.•Retromer vesicles are not dependent on the integrity of the chromatoid body.•Retromer vesicles are involved in the acrosome formation. Spermatozoa are produced during spermatogenesis as a result of mitotic proliferation, meiosis and cellular differentiation. Postmeiotic spermatids are exceptional cells given their haploid genome and remarkable sperm-specific structural transformations to compact and reshape the nucleus and to construct the flagellum and acrosome. These processes require delicate coordination and active communication between distinct cellular compartments. In this study, we elucidated the interplay between the haploid RNA regulation and the vesicular transport system. We identified a novel interaction between VPS26A/VPS35-containing retromer vesicles and the chromatoid body (CB), which is a large ribonucleoprotein (RNP) granule unique to haploid male germ cells. VPS26A/VPS35-positive vesicles were shown to be involved in the endosomal pathway, as well as in acrosomal formation that is dependent on the Golgi complex-derived vesicular trafficking. While the exact role of the retromer vesicles in the CB function remains unclear, our results suggest a direct functional link between vesicle transport and CB-mediated RNA regulation.