MAYORGA Luis Segundo
congresos y reuniones científicas
Marcks is phosphorylated during acrosomal exocytosis in living human sperm.
RODRIGUEZ PEÑA, M; MAYORGA, LS; MICHAUT, M.A.
Congreso; 48º SAIB; 2012
To fertilize the egg, human sperm must secrete the acrosomal content, a process known as acrosomal exocytosis (AE). Different pathways are activated during AE and protein phosphorylation is one of the mechanisms involved in this secretory event. It is known that MARCKS sequesters PIP2 against membranes and when it is phosphorylated, the protein is released to cytosol increasing the availability of PIP2. We previously showed that MARCKS is expressed in human sperm, it participates in AE and regulates PIP2 availability and Ca2+ mobilization during AE in human sperm. In this study, we hypothesized that, to allow AE, MARCKS must be phosphorylated during AE stimulated by physiological and nonphysiological stimulators. To test this we performed Western blot analysis using a specific anti-phospho-MARCKS antibody, which only recognizes the phosphorylated form of MARCKS. Human sperm were incubated with 2-ABP to prevent membrane loss and AE was stimulated by different activators in living sperm. The results showed that the phosphorylated form of MARCKS increased an 50%, 60% and 40% when AE was stimulated by calcium ionophore A23187, PMA, and progesterone, respectively, when compared to control conditions. The fact that MARCKS is phosphorylated duringAE is compatible with the idea that in human sperm MARCKS might be released from membranes increasing the availability of PIP2.