Gap junctions coupling and yolk uptake in Xenopus oocytes

MÓNACO ME; GUTIÉRREZ M; VILLECCO EI; SÁNCHEZ S

Guaruja, Sao Paulo, Brazil.

Congreso; 2nd International Meering of the Latin American of Developmental Biologyeting; 2005

Premeiotic Xenopus laevis oocytes undergo a rapid period of development characterized by the accumulation of yolk proteins. This selective uptake of vitellogenin is accomplished by receptor-mediated endocytosis. Hormonal stimulation triggering synthesis and processing of vitellogenin into mature yolk platelets has been intensely studied and follicle epithelial cells are known to contribute in this process. However, there has been little evidence that direct gap junction communication is a requirement for endocytic activity by oocyte. In this study we explore the role of gap junction intercellular communication during Xenopus vitellogenesis. In untreated control vitellogenic follicles dye coupling via gap junction occur and this follicles incubated in vitro in physiological salt solutions containing vitellogenin and fluorescein isothiocyanate-dextran o biotin-albumin, produced labeled nascent yolk platelets. In the follicles treatment with 1 mM octanol dye coupling was blocked and receptor-mediated endocytic uptake of vitellogenin was abolished; and no labeled yolk platelets were observed. This results suggest that coupling gap junction are involved on the endocytosis vitellogenin. On the other hand the investigation of mRNA connexin expression shown that the Cx 38 transcripts levels during oogenesis were high in vitellogenic oocytes compared with previtellogenic and mature oocytes.