TMF/ARA160 is a Golgi-associated protein to which several cellular activities have been attributed. These include, trafficking of Golgi-derived vesicles and E3 ubiquitin ligase activity. Here we show that TMF/ARA160 is required for the onset of key processes which underlie the development of mature sperm in mammals.TMF/ARA160 is highly expressed in specific spermatogenic stages. While the protein is not detected in the spermatogenic progenitor cells - spermatogonia, it accumulates in the Golgi of spermatocytes and spermatids but then disappears and is absent from spermatozoa and epididymal sperm cells. Mice that are homozygous null for TMF develop normally are healthy and the females are fertile. However, the males are sterile and their spermatids suffer from several developmental defects. They lack homing of Golgi-derived proacrosomal vesicles to the perinuclear surface, resulting in spermatozoa and epididymal sperm cells which lack acrosome. In a later developmental stage, the cytoplasm is not properly removed, thus resulting in spermatids which bare the nucleus with tightly packed DNA, surrounded by a cytoplasm. Finally, the spermatozoa of TMF-/- mice also suffer from misshaped heads, tails coiling around the sperm heads, and lack of motility. Taken together our findings portray TMF/ARA160 as a key regulator which is essential for the onset of key events in the differentiation and maturation of mammalian sperm and whose absence severely compromises their ability to fertilize ova.
Bibliographical noteFunding Information:
This work was supported by grants from the Israel Ministry of Health , and from the Ihel foundation . We thank Dr. Yehuda Gubbay for the assistance with the gene targeting procedure and Dr. Tatiana Babushkin and Dr. Shlomit Rabinovitz for the assistance in histological analysis. Dr. Rebecca Haffner from the veterinary resources facility at the Weizmann Institute of Sciences (Rehovot, Israel) is acknowledged, under whose supervision all work involving ES cells culture and maintenance, aggregation and implantation was carried out.
- Cytoplasm removal