Editors' ChoiceSpermatogenesis

Ubiquinating Defective Sperm

Science's STKE  24 Apr 2001:
Vol. 2001, Issue 79, pp. tw7
DOI: 10.1126/stke.2001.79.tw7

Sutovsky et al. may have identified one mechanisms for quality control of spermatogenesis. They show that abnormal mammalian sperm are ubiquitinated on their surfaces as they pass through the epididymis. Ubiquitination of these defective sperm appears to represent a tag for their phagocytosis by the epididymal epithelial cells (EECs). The ubiquitination and phagocytosis of sperm by EECs was reconstituted in vitro using a primary EEC culture. The damaged sperm present in the cultures became ubiquitinated and could be identified in intracellular structures in the EECs. The EECs also bound and phagocytosed ubiquitin-coated magnetic beads, confirming that ubiquitin represents a tag for phagocytosis. Thus, extracellular ubiquitination of defective sperm may be one mechanism for quality control during spermatogenesis. A question that remains unanswered is how the EECs know which sperm are abnormal.

P. Sutovsky, R. Moreno, J. Ramalho-Santos, T. Dominko, W. E. Thompson, G. Schatten, A putative, ubiquitin-dependent mechanism for the recognition and elimination of defective spermatozoa in the mammalian epididymus. J. Cell Sci. 114, 1665-1675 (2001). [Online Journal]