ABCA17 mediates sterol efflux from mouse spermatozoa plasma membranes
Carlos R. Morales1, Xiaoyan Ni1, Charles E. Smith1, Nobuya Inagaki2 and Louis Hermo1
1Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada and 2Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Offprint requests to: Carlos R. Morales, Department of Anatomy and Cell Biology, McGill University, 3640 University Street, Montreal, Quebec, Canada. e-mail: carlos.morales@mcgill.ca
Summary. Mammalian spermatozoa lose plasma membrane cholesterol during maturation in the epididymis and during capacitation in the female reproductive tract. While cholesterol acceptors such as high-density lipoproteins (HDL) and apolipoproteins A-I (apoA-I) and J (Apo J) have been found in male and female reproductive tracts, transporters that mediate cholesterol efflux from plasma membranes of spermatozoa to acceptors are not well defined. Candidates include members of the ATP-binding cassette (ABC) transporter superfamily including ABCA1, ABCA7, ABCA17, and ABCG1. In this study, we utilize immunocytochemistry on sections of adult mouse testis and epididymis and RT-PCR on isolated germ cells. The data reveal that ABCA17 is expressed by steps 12-16 elongated spermatids in the mouse in testis and by spermatozoa in the lumen of the epididymis where ABCA17 localizes to the sperm head and tail midpiece. It also localizes on these areas of mouse sperm isolated from the epididymis. Moreover, ABCA17 antibody interferes with cholesterol efflux from spermatozoa to lipid acceptors apoA-I. Taken together, these results suggest that ABCA17 plays an important role in the process of sterol efflux which renders spermatozoa capable of fertilizing an oocyte. Histol Histopathol 27, 317-328 (2012)
Key words: ATP-binding cassette transporters, ABCA17, Cholesterol efflux, Mouse testis, Sperm
DOI: 10.14670/HH-27.317