Angiotensin II type 2 receptor is expressed in human sperm cells and is involved in sperm motility
Fertil Steril. Mar.
2016 doi: 10.1016/j.fertnstert.2015.11.004
OBJECTIVE: To investigate the presence of angiotensin II type 2 receptor (AT2R) in human spermatozoa and its implication in sperm fertility status. DESIGN: We carried out expression assays for AT2R by reverse transcription-polymerase chain reaction, Western blot, immunofluorescence, and flow cytometry techniques in human sperm cells. Percentage of AT2R-positive sperm cells was analyzed by flow cytometry. SETTING: Assisted reproduction unit and academic research laboratory. PATIENT(S): Ninety-seven human semen samples from the Clinica IVI Bilbao. INTERVENTION(S): All samples were examined and classified according to World Health Organization guidelines. Spermatozoa were isolated from semen on discontinuous colloidal silica gradient (45%-90%) and swim-up techniques. MAIN OUTCOME MEASURE(S): Presence and location of the AT2R in spermatozoa and percentage of AT2R-positive sperm cells measured by flow cytometry. RESULT(S): We demonstrated the existence of AT2R and its transcript in human sperm by Western blot and reverse transcription-polymerase chain reaction. Immunofluorescence studies showed that AT2R is mainly located at the equatorial segment of the sperm head. The AT2R levels were associated with sperm motility parameters. Particularly, we found a significant positive correlation between AT2R and spermatozoa with progressive motility grade and a significant negative correlation with immotile spermatozoa, both in fresh semen samples and in prepared sperm cells. Regarding pathologic studies, the levels of AT2R measured by flow cytometry were lower in spermatozoa of asthenozoospermic men than in normozoospermic controls. CONCLUSION(S): Angiotensin II type 2 receptor is present in human semen and may be involved in the control of sperm motility. In-depth understanding of the proteins involved in sperm motility can help to elucidate the role of these proteins in male infertility as well as to establish new biomarkers for male infertility.