Cholesterol depletion by methyl-beta-cyclodextrin inhibits Bufo arenarum oocyte maturation

BUSCHIAZZO J., BONINI I.C., BISCOGLIO M. Y ALONSO T.S.

Mar del Plata, Buenos Aires, Argentina

Congreso; XLIII Reunion Anual de la Sociedad Argentina de Investigaciones en Bioquimica y Biologia Molecular (SAIB),; 2007

SAIB

Caveolae are small plasma membrane invaginations enriched in sphingolipids and cholesterol involved in cell signaling regulation. Cholesterol-enriched low-density membranes containing an immunodetectable caveolin-like protein from Bufo arenarum oocytes have been isolated. To further characterize these membranes, a distinctive band was identified as a non-muscle myosin heavy chain by mass spectrometry (ESI-MS/MS). In addition, a signal molecule such as c-Src associated to this membrane fraction, was detected by immunoblot.  In order to explore the involvement of cholesterol in the maturation process, oocytes arrested in G2 of meiosis I were treated with 5-50 mM methyl-ƒÀ-cyclodextrin (MƒÀCD) at room temperature for 60 minutes. The cholesterol content of treated oocytes decreased when compared with control oocytes. When MƒÀCD-treated oocytes were incubated with progesterone, the in vitro maturation was inhibited in a dose-dependent manner. MƒÀCD alone didnLt induce germinal vesicle breakdown. Repletion of cholesterol showed a recovery of the maturation ability of MƒÀCD-treated oocytes, particularly at the 25 mM concentration in which the reversibility was near the controls level. Results suggest that oocyte caveolae-like structures play a role in signaling mechanisms operating in Bufo oocytes maturation.