INVESTIGADORES
MAYORGA Luis Segundo
congresos y reuniones científicas
Título:
Ceramide regulates acrosomal exocytosis in human sperm.
Autor/es:
VAQUER, CC; SUHAIMAN, L; PELLETÁN, LE; MAYORGA LS; BELMONTE SA
Lugar:
Mendoza
Reunión:
Congreso; SAIB 48º; 2012
Institución organizadora:
SAIB
Resumen:
Sphingolipid metabolism involves multiple metabolic steps that
constitute a complex network. Ceramide is a metabolic hub because
is generated either via de novo pathway or the sphingomyelin and it
occupies a central position in sphingolipid biosynthesis and
catabolism. Ceramide positively regulates membrane fusion in
some biological systems even though has the opposite effect in other
cell types. Regulated secretion is a central issue; for instance,
mammalian sperm acrosomal exocytosis (AE) is essential for egg
fertilization. Since we demonstrated that sphingosine-1-phosphate,
an almost immediate product of ceramide breakdown, induces AE
we wondered if ceramide has any effect on exocitosis and if it is so
whether it is produced by itself or through the synthesis of bioactive
lipids. By using Western blot of sperm extracts, we found a ~84 kDa
band corresponding to neutral ceramidase, a hydrolase that removes
the fatty acyl groups from ceramides at neutral pH. It binds to sperm
membranes in a calcium independent manner. The alkaline
ceramidase (~31 kDa), was also present in human sperm. Neutral
sphingomyelinase, which generates ceramide, is present in sperm
extracts (~48 kDa). Functional assays demonstrated ceramide
regulation of AE. Here, we present the first piece of evidence
indicating the presence of sphingolipids metabolism enzymes in
human sperm and the importance of ceramides inAE.