Signalling events during Xenopus laevis vitellogenesis

SERRANO, MA; LUQUE, ME; SÁNCHEZ, SS

Montevideo

Congreso; LASDB; 2012

Latin American Society for Developmental Biology

P { margin-bottom: 0.21cm; direction: ltr; color: rgb(0, 0, 0); }P.western { font-family: "Liberation Serif","Times New Roman",serif; font-size: 12pt; }P.cjk { font-family: "WenQuanYi Micro Hei"; font-size: 12pt; }P.ctl { font-family: "Lohit Hindi"; font-size: 12pt; } Thedevelopmentofoogoniaintooocytesisdescribedasoogenesis.Inmanyoviparousvertebratesthegrowthofoocytesistheresultofacellregulationprocess,calledvitellogenesis.Thisprocessischaracterizedbyhepaticproductionoftheglycoproteinvitellogenin(VTG)thatistransportedviathebloodstreamtotheovarywhereitisincorporatedbyoocytes. Intheamphibianovarythethreedifferentstagesprevitellogenesis,vitellogenesisandmaturationareregulatedbythreekindsofsignals:endocrine(gonadotropins,estrogens),paracrine(TGF-B,BMPsandActivins)andjuxtacrinemediatedbygapjunctions(Ca++,cAMP/IP3). Toanalysetheparticipationofparacrinesignalling,wedeterminedthegeneexpressionofXepacandBMPsignallingpathwaycomponents.TheresultsshowedthepresenceofXepac,BMP2,4,7andtheirreceptorsduringX.laevisoogenesis. TodeterminetheroleofIP3 and Xepac duringvitellogenesisweperformedassayswithdifferentinhibitors.OocytesweretreatedwithU-73122(PLCspecificinhibitor),verapamil, nifedipine, diltiazem and amiloride (to block voltage-operated channels), theophylline (phosphodiesterase inhibitor), neomycin (PIP2 hydrolysis inhibitor) and H89 (Protein kinase A inhibitor). Rescue experiments were performed with cdbAMP (Dibutyryl cyclic-AMP) and with A23187 (calcium ionophore). TheresultsshowedthatIP3signallingpathwayisimplicatedinVTGuptake. Becauseofthis,wesuggestthatoogenesisisacomplexprocesscoordinatedbyacross-talkbetweenthemoleculesofdifferentsignallingpathways.