Cyclic AMP levels during the maturation of Xenopus oocytes

Cicirelli, Michael F.; Smith, L.Dennis

doi:10.1016/0012-1606(85)90029-6

Cited by 75 publications

(37 citation statements)

References 26 publications

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“…Although cAMP levels show a partial, transient drop soon after progesterone addition and another drop before GVBD (15,18,54,55), total cellular PKA activity shows only minor fluctuations in activity between progesterone addition and GVBD (data not shown). Taken together, these results suggest that the phosphorylation status of cdc25 on Ser-287 could be controlled by selective, compartmentalized binding of cdc25, PKA, and the Ser-287 phosphatase to one of the substrate-specific PKA scaffolding proteins known as AKAPs (56,57).…”

Section: Resultsmentioning

confidence: 94%

G ₂ arrest in Xenopus oocytes depends on phosphorylation of cdc25 by protein kinase A

Duckworth

Weaver

Ruderman

2002

Proc. Natl. Acad. Sci. U.S.A.

198

209

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Xenopus oocytes, which are arrested in G2 of meiosis I, contain complexes of cyclin B-cdc2 (M phase-promoting factor) that are kept repressed by inhibitory phosphorylations on cdc2 at Thr-14 and Tyr-15. Progesterone induces a cytoplasmic signaling pathway that leads to activation of cdc25, the phosphatase that removes these phosphorylations, catalyzing entry into M phase. It has been known for 25 years that high levels of cAMP and protein kinase A (PKA) are required to maintain the G 2 arrest and that a drop in PKA activity is required for M phase-promoting factor activation, but no physiological targets of PKA have been identified. We present evidence that cdc25 is a critical target of PKA. (i) In vitro, cdc25 Ser-287 serves as a major site of phosphorylation by PKA, resulting in sequestration by 14-3-3. (ii) Endogenous cdc25 is phosphorylated on Ser-287 in oocytes and dephosphorylated in response to progesterone just before cdc2 dephosphorylation and M-phase entry. (iii) High PKA activity maintains phosphorylation of Ser-287 in vivo, whereas inhibition of PKA by its heat-stable inhibitor (PKI) induces dephosphorylation of Ser-287. (iv) Overexpression of mutant cdc25 (S287A) bypasses the ability of PKA to maintain oocytes in G 2 arrest. These findings argue that cdc25 is a physiologically relevant target of PKA in oocytes. In the early embryonic cell cycles, Ser-287 is phosphorylated during interphase and dephosphorylated just before cdc2 activation and mitotic entry. Thus, in addition to its role in checkpoint arrest, cdc25 Ser-287 serves as a site for regulation during normal, unperturbed cell cycles.

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Section: Resultsmentioning

confidence: 94%

G ₂ arrest in Xenopus oocytes depends on phosphorylation of cdc25 by protein kinase A

Duckworth

Weaver

Ruderman

2002

Proc. Natl. Acad. Sci. U.S.A.

198

209

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“…There is, however, evidence supporting a role for steroid action through both a membrane receptor and classical steroid receptors (Masui and Markert, 1971;Bayaa et al, 2000;Tian et al, 2000;Evaul et al, 2007). In Xenopus, progesterone-induced oocyte maturation is associated with a rapid transient decline (20-60%) in cAMP (Maller et al, 1979;Cicirelli and Smith, 1985), due to inhibition of adenylate cyclase (AC) (Sadler and Maller, 1981;Sadler and Maller, 1985;Finidori-Lepicard et al, 1981). Furthermore, interventions that increase cAMP, either through activation of AC (Schorderet-Slatkine and Baulieu, 1982), increasing protein kinase A (PKA) activity (Maller and Krebs, 1977) or inhibiting cAMP phosphodiesterase (Bravo et al, 1978;Sadler and Maller, 1987), block progesteroneinduced oocyte maturation.…”

Section: Introductionmentioning

confidence: 99%

Vesicular traffic at the cell membrane regulates oocyte meiotic arrest

et al. 2007

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Vertebrate oocytes are maintained in meiotic arrest for prolonged periods of time before undergoing oocyte maturation in preparation for fertilization. Cyclic AMP (cAMP) signaling plays a crucial role in maintaining meiotic arrest, which is released by a species-specific hormonal signal. Evidence in both frog and mouse argues that meiotic arrest is maintained by a constitutively active G-protein coupled receptor (GPCR) leading to high cAMP levels. Because activated GPCRs are typically targeted for endocytosis as part of the signal desensitization pathway, we were interested in determining the role of trafficking at the cell membrane in maintaining meiotic arrest. Here we show that blocking exocytosis, using a dominant-negative SNAP25 mutant in Xenopus oocytes, releases meiotic arrest independently of progesterone. Oocyte maturation in response to the exocytic block induces the MAPK and Cdc25C signaling cascades, leading to MPF activation, germinal vesicle breakdown and arrest at metaphase of meiosis II with a normal bipolar spindle. It thus replicates all tested aspects of physiological maturation. Furthermore, inhibiting clathrin-mediated endocytosis hinders the effectiveness of progesterone in releasing meiotic arrest. These data show that vesicular traffic at the cell membrane is crucial in maintaining meiotic arrest in vertebrates, and support the argument for active recycling of a constitutively active GPCR at the cell membrane.

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“…8 In a continuous breeding study of boric acid in mice, a dose-related effect on the testis (testicular atrophy and effects on sperm, motility, morphology, and concentration) was noted; fertility was partially reduced at 111 mg B/kg/d, and totally reduced at 221 mg B/Kg/d. 9 In rats, at non-maternally toxic doses, there was a reduction in fetal body weight and some skeletal anomalies. 34 With the exception of shortened 13 th rib, these malformations had reversed by postnatal day 21 at 13.7 and 28.6 mg B/kg/d in a study designed to look at postnatal recovery.…”

Section: Discussionmentioning

confidence: 99%

“…The course of X laevis oocyte maturation and the associated biochemical changes have been extensively researched (Sato and Koide, 1984; Cicirelli and Smith, 1985; Taylor and Smith, 1987). Cicirelli and Smith (1985) found that levels of cyclic adenosine monophosphate (CANT) declined upon oocyte maturation. Exposure to toxicants that interfere with the decline in CANT levels cause the oocyte to remain in meiotic arrest, thereby impeding maturation.…”

Section: Rationale For Gametogenesis-based Endpoints In Assay Designmentioning

confidence: 99%

Development of a Reproductive Toxicity Test Using Xenopus

Bantle¹

1998

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Cyclic AMP levels during the maturation of Xenopus oocytes

Cited by 75 publications

References 26 publications

G ₂ arrest in Xenopus oocytes depends on phosphorylation of cdc25 by protein kinase A

G ₂ arrest in Xenopus oocytes depends on phosphorylation of cdc25 by protein kinase A

Vesicular traffic at the cell membrane regulates oocyte meiotic arrest

Development of a Reproductive Toxicity Test Using Xenopus

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Cyclic AMP levels during the maturation of Xenopus oocytes

Cited by 75 publications

References 26 publications

G 2 arrest in Xenopus oocytes depends on phosphorylation of cdc25 by protein kinase A

G 2 arrest in Xenopus oocytes depends on phosphorylation of cdc25 by protein kinase A

Vesicular traffic at the cell membrane regulates oocyte meiotic arrest

Development of a Reproductive Toxicity Test Using Xenopus

Contact Info

Product

Resources

About

G ₂ arrest in Xenopus oocytes depends on phosphorylation of cdc25 by protein kinase A

G ₂ arrest in Xenopus oocytes depends on phosphorylation of cdc25 by protein kinase A