IIBYT   23944
INSTITUTO DE INVESTIGACIONES BIOLOGICAS Y TECNOLOGICAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Uterine extracellular vesicles fuse to human spermatozoa and regulate intracellular calcium levels
Autor/es:
ANAHI FRANCHI; LAURA C. GIOJALAS; ANAHÍ BRAVO; ERNESTO GRASSO
Lugar:
Buenos Aires
Reunión:
Congreso; REUNIÓN CONJUNTA DE SOCIEDADES DE BIOCIENCIAS; 2017
Institución organizadora:
Sociedades de Biociencias
Resumen:
Cells can communicate via extracellular vesicles (EV), lipid bilayers containing transmembrane proteins, cytosolic proteins and RNA. EV consist of microvesicles and exosomes, and have been recently identified along the female reproductive tract, including the uterus. In a previous study we found that EV secreted by endometrial cells interact with human spermatozoa, and stimulate sperm capacitation up to 4-fold. Both capacitation and acrosome reaction are dependent on an increase in intracellular calcium level (Ca2+i). Based on our results, we hypothesized that the regulation of Ca2+i could be mediated by binding or fusion of EV with the spermatozoa. Fluorimentric measurements of (Ca2+i) were performed using Fura-4 AM. Two different Ca2+i kinetic patterns were observed when EV were added to spermatozoa: either a slow but sustained increase of Ca2+I, or a quick and transient increment of the Ca2+i. These results suggest that sperm response is mediated by two mechanisms: one dependent on the direct interaction between spermatozoa and EV, and another that requires the fusion spermatozoa-EV. Moreover, when EV were labeled with CMFDA -a fluorescent probe that is transformed into a non-permeable product once incorporated into the cells-, an increase in sperm fluorescence intensity was observed, suggesting that sperm cells incorporated EV. These data were corroborated by fusion experiments using the self-quenchable probe actacedyl rhodamine (R18). Furthermore, when endometrial cells were simultaneously treated with estrogen and progesterone, we observed that the ratio of microvesicles to exosomes was higher. Since these subpopulations were not physically isolated in our studies, to determine which one mediates sperm response to Ca2+i -or both- will require further investigation. In conclusion, our results show that endometrial EV fuse to human spermatozoa and regulate sperm intracellular calcium concentrations.