Effects of CXCL12/CXCR4/CXCR7 axis on human sperm motility and chemotaxis

Abstract

21Mammalian spermatozoa undergo a series of functional changes in the female 22 2 genital tract before they can fertilize oocytes. Chemokines and their receptors are 23 involved in these complex biological events. However, the detailed molecular 24 mechanisms on the modulation of chemokines on spermatozoa still need to be 25 elucidated. CXCL12, a chemokine, has been widely studied in leukocyte 26 migration and. Here we found that CXCL12 was existent in human cumulus cells 27 and follicular fluid and its receptors CXCR4 and CXCR7 were co-expressed on 28 human spermatozoa. We investigated the effects of CXCL12 on various 29 biological functions of human sperm and which receptor plays a dominant role in 30 these processes. We found that CXCL12 could promote human sperm chemotaxis, 31 motility, penetration in the mucus, acrosome reaction and Ca 2+ influx through 32 CXCR4 rather than CXCR7. In addition, the simplified physical model 33 reasonably explained the change of sperm velocity under the influence of 34 CXCL12 concentration gradient, which was identical to their physiological 35 motion patterns.36