Involvement of cAMP and calmodulin in endocytic yolk uptake duringXenopus laevisoogenesis

Abstract

The aim of the present study was to show the participation and physiological role of calmodulin (CaM) and cAMP during vitellogenin endocytic uptake in the amphibian Xenopus laevis. The results showed a differential distribution of CaM in the ovary follicles during oogenesis. The CaM intracellular localization was not affected by gap junction's downregulation and CaM inhibition did not completely abolished the endocytic activity of oocytes. We showed that cAMP was able to completely rescue the endocytic competence in follicles in which gap junctional communication had been disrupted by octanol. Moreover cAMP was capable of restoring oocyte endocytic capability in the presence of octanol and stelazine, a CaM inhibitor. We propose that, in Vtg uptake regulation, cAMP is upstream of CaM during the endocytic signalling pathway.

Xepac protein and IP3/Ca2+pathway implication duringXenopus laevisvitellogenesis

“…Moreover, this is congruent with our previous findings in which we proved a regulatory effect of the CaM-Ca 2+ complex in a downstream level regarding the cAMP (Luque et al, 2013), due to the formation of this complex is dependent on the cytoplasmic calcium level. finally, Xenopus vitellogenesis is the result of a well regulated increase of cytoplasmic calcium as a consequence of the cAMP-activated Xepac which might trigger the IP 3 /Ca 2+ pathway.…”

“…Therefore, once in the oocyte, the cAMP molecule (see Luque et al 2013 for more details) might bind to the Xepac protein and initiate a series of cytoplasmic signalling events that trigger the vitellogenin uptake process. Therefore, once in the oocyte, the cAMP molecule (see Luque et al 2013 for more details) might bind to the Xepac protein and initiate a series of cytoplasmic signalling events that trigger the vitellogenin uptake process.…”

“…Regarding this, we have demonstrated that direct gap-junctional communication is a requirement for the acquisition of endocytic competence by Xenopus laevis vitellogenic oocytes. Consequently, we determined that using the stable cell-permeable cAMP analogue dbcAMP (N 6 ,2 -O-dibutyryladenosine 3 -5cyclic monophosphate) in the incubation medium of oocytes in which gap junctions had been downregulated with octanol, the follicle endocytic activity is rescued (Luque et al, 2013) concluding that cAMP is the molecule that triggers the vitellogenin uptake by the oocytes. This evidence suggested that a signal molecule small enough to pass through open gap junctions could be involved at the onset of vitellogenin incorporation.…”

Double‐stranded RNA targeting calmodulin reveals a potential target for pest management of Nilaparvata lugens

“…In females with knockdown of NlCaM , the transcript levels of NlVg and NlVgR and levels of Vg protein in the whole body were not affected, while the Vg protein in ovaries was significantly reduced. A link between CaM and receptor‐mediated endocytosis of Vgs has been found in Xenopus oocytes and in insects such as Blattella germanica , Oncopeltus fasciatus and D. melanogaster . The results of the present study indicate that NlCaM is also necessary for endocytic uptake of yolk precursor molecules in oocytes in N. lugens .…”

Gonadotropin-Releasing Hormone for Preservation of Ovarian Function during Chemotherapy in Lymphoma Patients of Reproductive Age: A Summary Based on 434 Patients

“…Different approaches have been developed to preserve fertility in women exposed to chemotherapy, including gametes and ovarian tissue cryopreservation[2]. However, for ovarian tissue cryopreservation, the risk of transmitting malignant cells via ovarian transplantation may be relatively high for the blood-borne cancers such as leukemia and lymphoma[3].…”