Calcium and meiotic maturation of the mammalian oocyte

Homa, Sheryl T.

doi:10.1002/mrd.1080400116

Cited by 117 publications

(78 citation statements)

References 129 publications

(198 reference statements)

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“…The hypothesis of a possible involvement of CASR in oocyte maturation is supported by several studies reporting the Ca 2C ion as a fundamental messenger for oocyte maturation (Homa 1995, He et al 1997. The rise in cytosolic Ca 2C in immature oocytes (germinal vesicle (GV) stage) following LH and/or growth factor exposure is well known (Mattioli et al 1998, Hill et al 1999.…”

Section: Introductionmentioning

confidence: 93%

The extracellular calcium-sensing receptor is expressed in the cumulus–oocyte complex in mammals and modulates oocyte meiotic maturation

Santis¹,

Casavola²,

Reshkin³

et al. 2009

Reproduction

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The extracellular calcium-sensing receptor (CASR) plays an important role in cells involved in calcium (Ca 2C ) homeostasis by directly sensing changes in the extracellular Ca 2C ion concentration. We previously reported the localization and quantitative expression of CASR protein in human oocytes. In this study, we examined the expression and the functional role of CASR during oocyte meiotic maturation in a large mammal animal model, the horse. As in humans, CASR protein was found to be expressed in equine oocytes and cumulus cells. Western-blot analysis revealed a single 130 kDa band in denuded oocytes and a doublet of 130-120 kDa in cumulus cells. CASR labeling was observed by confocal microscopy in cumulus cells and in oocytes on the plasma membrane and within the cytoplasm at all examined stages of meiosis. Functionally, the CASR allosteric effector NPS R-467, in the presence of 2.92 mM external Ca 2C , increased oocyte maturation rate in a dose-dependent manner and its stimulatory effect was attenuated by pre-treatment with the CASR antagonist NPS 2390. NPS R-467 had no effect in suboptimal external Ca 2C (0.5 mM), indicating that it requires higher external Ca 2C to promote oocyte maturation. In oocytes treated with NPS R-467, CASR staining increased at the plasmalemma and was reduced in the cytosol. Moreover, NPS R-467 increased the activity of MAPK, also called ERK, in cumulus cells and oocytes. These results provide evidence of a novel signal transduction pathway modulating oocyte meiotic maturation in mammals in addition to the well-known systemic hormones.

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Section: Introductionmentioning

confidence: 93%

The extracellular calcium-sensing receptor is expressed in the cumulus–oocyte complex in mammals and modulates oocyte meiotic maturation

Santis¹,

Casavola²,

Reshkin³

et al. 2009

Reproduction

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“…To date, little information is available on the function of this ion during oocyte maturation; however, an integral attribute of oocyte maturation is the remodeling of calcium signaling pathways endowing the oocyte with the capacity to produce a specialized calcium transient at fertilization [Homa 1995;Carroll et al 1996;Machaca 2007;Boni et al 2007]. Recent studies have shown that cytoplasmic maturation is also accompanied by a modification of plasma membrane permeability due to ion currents flowing through ion channels located on the plasma membrane.…”

Section: Introductionmentioning

confidence: 99%

Ion currents modulating oocyte maturation in animals

Tosti

Boni

Gallo

et al. 2013

Systems Biology in Reproductive Medicine

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Growing oocytes are arrested at the first prophase of meiosis which is morphologically identified by the presence of a large and vesicular nucleus, called the germinal vesicle. The dissolution of the germinal vesicle marks the resumption of meiosis during which the oocyte undergoes massive modifications up to the second meiotic block, which is removed at fertilization. The interval between the first and the second meiotic block is defined as maturation and the events occurring during this period are crucial for ovulation, fertilization, and embryo development. Oocytes are excitable cells that react to stimuli by modifying their electrical properties as a consequence of ion currents flowing through ion channels on the plasma membrane. These electrical changes have been largely described at fertilization whereas little information is available during oocyte maturation. The aim of this review is to give an overview on the involvement of ion channels and ion currents during oocyte maturation in species from invertebrates to mammals. The results summarized here point to the possible functional role of ion channels underlying oocyte growth and maturation.

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“…This results in GVBD. The presence of low frequency spontaneous calcium oscillations, generated perhaps as a consequence of a n autonomous program, may be sufficient to activate some of the cyclins required for the transition from G, stage to metaphase (G,/M) at a relatively early stage of development (Homa, 1995). The resumption of meiotic maturation of mammalian oocyte is regulated by intracellular free calcium.…”

Section: Resultsmentioning

confidence: 99%

“…Studies concerning the effects of extracellular calcium on resumption of meiosis have been carried out using calcium deficient media, calcium chelators, calcium channel blockers a n d calcium ionophores (Homa, 1995). However, evidence for the role of extracellular calcium on GVBD remains contradictory.…”

Section: Resultsmentioning

confidence: 99%