Signal molecules implicated in Xenopus laevis vitellogenin uptake.

SERRANO M.A.; LUQUE M.E.; MÓNACO M.E.; VILLECCO E.I.; SÁNCHEZ S.S.

San Miguel de Tucumán, Tucumán, Argentina.

Congreso; XLV Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology (SAIB).; 2009

SAIB

The transformation of oogonia into oocytes is commonly described as oogenesis. In many oviparous vertebrates the growth of oocytes from microscopic to macroscopic dimensions is mainly the results of one of the most exciting examples of cell regulation, named vitellogenesis. This process, general to all oviparous vertebrates species is characterized by hepatic production of the glycoprotein vitellogenin (VTG). VTG is transportated via the bloodstream to the ovary where enters the oocytes by a receptor-mediated endocytosis. Previously we demonstrated that in the amphibian Xenopus laevis the follicular epithelium and gap junctions are involved in VTG uptaking. This suggested us that a diffusible signal molecule (cAMP or/and Calmodullin) able to pass through fully open gap junctions could be involved in vitellogenin uptaking.               In order to determine the identity of the signal molecule, we analyzed the CaM immunolocalization and the biotinylated bovine serum albumin (b-BSA) uptaking in amphibian oocytes with closed gap junction by octanol in the presence of dbcAMP.(a cAMP analog). We found that the uptaking was normal in the presence of dbcAMP. This findings and inmunohistochemestry results suggest that the cAMP could be the signal molecule involved in vitellogenin uptaking during vitellogenesis.