Tmc7 deficiency causes acrosome biogenesis defects and male infertility in mice

Transmembrane channel-like (Tmc) proteins are a highly conserved ion channel family consisting of eight members (TMC1–TMC8) in mammals. TMC1/2 are components of the mechanotransduction channel in hair cells, and mutations of TMC1/2 cause deafness in humans and mice. However, the physiological roles of other TMC proteins remain largely unknown. Here, we show that Tmc7 is specifically expressed in the testis and that it is required for acrosome biogenesis during spermatogenesis. Tmc7 −/− mice exhibited complete male infertility due to abnormal sperm morphology, similar to human oligo-astheno-teratozoospermia. We further demonstrate that Tmc7 is colocalized with Gm130 at the cis-Golgi region in round spermatids. Tmc7 deficiency leads to aberrant Golgi morphology and impaired fusion of Golgi-derived vesicles to the developing acrosome. Moreover, upon loss of Tmc7 Golgi pH and ion homeostasis is impaired and ROS levels are increased, which in turn causes Golgi and endoplasmic reticulum (ER) stress. Taken together, these results suggest that Tmc7 is required to maintain Golgi pH and ion homeostasis, which is needed for acrosome biogenesis. Our findings unveil a novel role for Tmc7 in acrosome biogenesis during spermiogenesis. ### Competing Interest Statement The authors have declared no competing interest.