The detection of α5 integrin and membrane progesterone receptor (mPr) increase during human sperm capacitation

DÍAZ, EMILCE; POZO, P.; MARTÍNEZ, EDUARDO; MORALES, PATRICIO

Montreal

Congreso; Society for Study of Reproduction SSR 46th Annual meeting; 2013

Society for Study of Reproduction (SSR)

The Detection of Alpha 5 Integrin and Membrane Progesterone Receptor Increase During Human Sperm Capacitation. Emilce S. Diaz , Patricia Pozo , Eduardo Martinez , Boris Perez , Patricio Morales . Biology of Reproduction Laboratory, University of Antofagasta, Antofagasta, Antofagasta, Chile Previously, we determined that there are sperm subpopulations that express, independently and simultaneously, the integrin alpha 5 (fibronectin receptor) and the membrane progesterone receptor (mPr). When these sperm populations are stimulated with both progesterone and fibronectin, a cooperative increase in the percentage of acrosome reacted cells takes place. Non-capacitated sperm are unable to undergo the acrosome reaction in response to progesterone and/or fibronectin. Since the spermatozoon is a highly differentiated, transcriptionally inactive 1 1 1 1 1 1 198    cell (cannot synthesize new proteins), it must have all the required molecules to accomplish its task, including receptors for acrosome reaction- inducing ligands. It is known that integrins and the mPr must undergo conformational changes to be active receptors. The aim of this work is to determine whether the detection of active alpha 5 integrin and mPr receptor changes during human sperm capacitation. For this, aliquots of motile sperm, selected by Percoll gradient, were incubated under capacitating conditions for 0, 5, and 18 h. At each time, sperm aliquots were taken to determine the percentage of sperm expressing the integrin alpha 5 and the mPr. For this, sperm were stained with an anti-alpha 5 integrin antibody and an anti-mPr antibody, conjugated with different fluorochromes. The detection was carried out by flow cytometry and immunofluorescence microscopy. In addition, other aliquots were treated with fibronectin or progesterone and the sperm acrosomal status was evaluated using the PSA-FITC technique. The results indicate that the percentaje of sperm expressing the alpha 5 integrin and the mPr increase during capacitation, which is related to the increase in the percentage of acrosome reacted sperm induced by fibronectin or progesterone. Since the processes of transduction and transcription are inactive in the sperm, the detected changes may be attributed to conformational changes or variations in the subcellular distribution of the proteins detected in this work.