IHEM   20887
INSTITUTO DE HISTOLOGIA Y EMBRIOLOGIA DE MENDOZA DR. MARIO H. BURGOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Rab3A regulates the stability of exocytotic fusion pores in human sperm
Autor/es:
TOMES CLAUDIA NORA
Lugar:
Mar del Plata
Reunión:
Congreso; Sociedad Argentina de Investigación en Neurociencias; 2017
Institución organizadora:
Sociedad Argentina de Investigación en Neurociencias
Resumen:
Secretory cells undergo regulated exocytosis in response to physiological signals. At the final stage of exocytotis, a fusion pore opens between the plasma and a secretory vesicle membranes; typically, when the pore dilates the vesicle releases its cargo. My lab uses the exocytosis of the acrosomal vesicle of human sperm (the acrosome reaction or AR) as model system. Each sperm contains a single, very large and electron dense granule whose contents are secreted by regulated exocytosis at fertilization. The acrosomal membrane fuses at multiple points with the plasma membrane that overlies the anterior part of the head. Joining of pores originates hybrid plasma membrane-outer acrosomal membrane vesicles. The AR is completed when vesicles and acrosomal contents are shed. The exocytosis of the acrosome depends on members of the standard fusion machinery, including small GTPases and SNAREs. Geranylgeranylated and active Rab3A elicits the AR per se. Its carboxy-terminus domain is necessary and sufficient to promote exocytosis whereas its amino-terminus prevents calcium-triggered secretion. because it stabilizes open fusion pores. Sperm SNAREs engage in α-SNAP/NSF-sensitive complexes at a post-fusion stage. In other words, vesiculation is not spontaneous; rather, post-fusion regulation of the pores determines their expansion and the success of the AR.