RESUMO
Although recent studies have revealed that germline stem cells (GSCs) exist in the mouse postnatal ovary, how to efficiently obtain GSCs for regenerating neo-oogenesis is still a technical challenge. Here, we report that using in situ tissue culture we can efficiently accumulate large amounts of proliferating germ-like cells from mouse postnatal ovaries. Usually, more than 10,000 germ-like cells can be derived from one ovary by this method, and over 20% of these cells can grow into germ-like cells with self-renewal, which thus can serve as a good cell pool to isolate GSCs by other cell assorting methods such as FACS. This method is simple and time-saving, which should be useful for in future studies on mouse GSCs.
Assuntos
Células Germinativas/citologia , Ovário/citologia , Células-Tronco/citologia , Técnicas de Cultura de Tecidos , Animais , Proliferação de Células , Feminino , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Alteration of intrauterine growth trajectory is linked to metabolic diseases in adulthood. In mammalian and, specifically, human species, pregnancies through assisted reproductive technology (ART) are associated with changes in intrauterine growth trajectory. However, it is still unclear how ART alters intrauterine growth trajectory, especially reduced fetal growth in early to midgestation. In this study, using a mouse model, it was found that ART procedures reduce fetal and placental growth at Embryonic Day 10.5. Furthermore, ART leads to decreased methylation levels at H19, KvDMR1, and Snrpn imprinting control regions in the placentae, instead of fetuses. Furthermore, in the placenta, ART downregulated a majority of parentally expressed imprinted genes, which enhance fetal growth, whereas it upregulated a majority of maternally expressed genes which repress fetal growth. Additionally, the expression of genes that regulate placental development was also affected by ART. ART also downregulated a majority of placental nutrient transporters. Disruption of genomic imprinting and abnormal expression of developmentally and functionally relevant genes in placenta may influence the placental development and function, which affect fetal growth and reprogramming.
Assuntos
Regulação para Baixo , Desenvolvimento Fetal/genética , Impressão Genômica , Técnicas de Reprodução Assistida , Animais , Desenvolvimento Embrionário/genética , Feminino , Camundongos , Placenta/metabolismo , Placentação/genética , GravidezRESUMO
To ascertain whether the Kunming (KM) mouse is an available model for age-related decline in female fertility in human or not, oocytes from young (6-8 weeks), middle-aged (9 months) and aged (12 months) female mice were compared with respect to number of oocytes, frequency of in-vitro maturation (IVM) and in-vitro fertilization (IVF), and meiotic chromosome segregation and alignment. The mean number of pups born per mouse decreased significantly from the young to the middle-aged and the aged mice. The mean number of ovarian follicles, ovarian germinal vesicle oocytes and ovulated MII oocytes decreased significantly with maternal age. The rate of IVM in oocytes from young mice (73.9%) was less significantly than that in oocytes from middle-aged and aged mice (86.1% and 84.4%, respectively). Immunocytochemical analysis showed that ageing caused a significantly higher rate (49.3%) of chromosome misalignment than that (15.7%) of the young mice. The presence of premature chromatids was also significantly higher in MII oocytes of aged mice as compared with young mice (37.8 versus 8.3%). Pronuclear formation was delayed in oocytes of middle-aged and aged females (35.5 and 42.3% respectively in 5 h of IVF) as compared with young mice (88.1%). The study suggests that KM mouse exhibits an age-related decline in female fertility. Significant reduction of germinal vesicle (GV) and MII oocytes and significant increase of metaphase chromosome misalignment and premature chromatid segregation after meiotic maturation of oocytes, similar to human, presumably contribute to the decline in aged KM mice.
Assuntos
Envelhecimento , Fertilidade/fisiologia , Infertilidade Feminina/etiologia , Oócitos/citologia , Animais , Núcleo Celular/genética , Feminino , Fertilização in vitro , Imunofluorescência , Humanos , Técnicas Imunoenzimáticas , Masculino , Meiose/fisiologia , CamundongosRESUMO
PURPOSE: Histone H3 lysine 9 (H3K9) methylation plays an important role in the regulation of preimplantation embryo development. G9a has been reported to be a major H3K9mono (m1)/dimethylation(m2) methyltransferase and to contain nuclear localization signals. This study was performed to investigate the correlation between H3K9 methylation level and G9a localization when the nuclear membrane undergoes periodic reconstruction in the cell cycle during preimplantation embryo development. METHODS: The fluorescence intensity was examined via immunofluorescence. The mRNA expression of G9awas determined using real-time reverse transcriptase (RT)-PCR. Eight-cell embryos were cultured in KSOM supplemented with nocodazole (0.5 µM) for 12 h. RESULTS: In this study, it was observed that the fluorescence intensity of H3K9m2 and G9a began to increase significantly from the 4-cell stage and reached the peak at the morula stage (p < 0.001), but the fluorescence intensity declined to 4-cell-stage levels when it reached the blastula stage. We observed a similar pattern when we examined G9a mRNA expression. Once the nuclear membrane disintegrated, G9a and H3K9m1 were not detectable by immunofluorescence; when it was reconstructed, G9a and H3K9m1 had relocated to the cell nucleus. However, no significant change was observed in the H3K9m2 localization or in the G9a mRNA level (p > 0.05) during the whole process. JHDM2A was consistently localized in the cytoplasm irrespective of the presence or absence of a nuclear membrane. CONCLUSION: These results indicate dynamic changes in the expression level of H3K9m2 and G9a as preimplantation embryogenesis progresses. G9a co-localized with H3K9 m1 in a nuclear membrane-dependent manner during mouse preimplantation embryo development.
Assuntos
Desenvolvimento Embrionário/genética , Histonas/genética , Membrana Nuclear/genética , Animais , Blastocisto/citologia , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Histona-Lisina N-Metiltransferase , Lisina/genética , Metilação , Camundongos , Sinais de Localização Nuclear , GravidezRESUMO
OBJECTIVES: To date, the effectiveness of acceptance and commitment therapy (ACT) for acute stroke patients has not been well recognized. The study aimed to discover the effectiveness of group-based ACT in treating depression for acute stroke patients. METHODS: We conducted a randomized controlled trial with 140 acute stroke patients with depression. The ACT intervention comprised seven sessions, of 45-60 min over 4 weeks. Data were collected pre- and post-intervention and at 3-month follow-up, assessing depression, health-related quality of life (HRQoL), psychological flexibility, cognitive fusion, sleep quality, and confidence. RESULTS: Overall, 99.3% of the included patients were assessed as having mild depression. The ACT intervention significantly reduced depression in acute stroke patients in comparison with the control group post-intervention and at 3 months (partial η 2 = . 306 $\eta^{2}=.306$ ). Additionally ACT significantly improved HRQoL-mental component summary, sleep quality, psychological flexibility, cognitive fusion, and confidence compared with control group. CONCLUSIONS: ACT is effective in treating acute stroke patients with depression, and the efficacy was maintained at 3-month follow-up.
Assuntos
Terapia de Aceitação e Compromisso , Acidente Vascular Cerebral , Humanos , Depressão/terapia , Qualidade de Vida , Acidente Vascular Cerebral/complicações , Acidente Vascular Cerebral/terapia , Acidente Vascular Cerebral/psicologia , Resultado do TratamentoRESUMO
Protein kinase C (PKC) is a family of Ser/Thr protein kinases that can be activated by Ca2+, phospholipid and diacylglycerol. There is evidence that PKC plays key roles in the meiotic maturation and activation of mammalian oocytes. The present study aimed to monitor the effect of age, germinal vesicle (GV) transfer and modified nucleoplasmic ratio on the subcellular distribution profile of PKCα, an important isozyme of PKC, in mouse oocytes undergoing meiotic maturation and following egg activation. Germinal vesicle oocytes were collected from 6-8-week-old and 12-month-old mice. Germinal vesicle-reconstructed oocytes and GV oocytes with one-half or one-third of the original oocyte volume were created using micromanipulation and electrofusion. The subcellular localization of PKCα was detected by immunocytochemistry and laser confocal microscopy. Our study showed that PKCα had a similar location pattern in oocytes and early embryos from young and old mice. PKCα was localized evenly in ooplasm, with weak staining in GV at the GV stage, and present in the entire meiosis II (MII) spindle at the MII stage. In pronuclear and 2-cell embryos, PKCα was concentrated in the nucleus except for the nucleolus. After the GV oocytes were reconstructed, the resultant MII oocytes and embryos showed a similar distribution of PKCα between reconstructed and unreconstructed controls. After one-half or two-thirds of the cytoplasm was removed from the GV oocytes, PKCα still had a similar location pattern in MII oocytes and early embryos from the GV oocytes with modified nucleoplasmic ratio. Our study showed that age, GV transfer and modified nucleocytoplasmic ratio does not affect distribution of PKCα during mouse oocyte maturation, activation, and early embryonic mitosis.
Assuntos
Núcleo Celular/metabolismo , Citoplasma/metabolismo , Embrião de Mamíferos/metabolismo , Oócitos/metabolismo , Proteína Quinase C-alfa/metabolismo , Fatores Etários , Animais , Embrião de Mamíferos/citologia , Desenvolvimento Embrionário , Feminino , Fertilização in vitro , Imuno-Histoquímica , Técnicas de Maturação in Vitro de Oócitos , Masculino , Meiose , Camundongos , Micromanipulação , Microscopia Confocal , Oócitos/citologia , Oócitos/crescimento & desenvolvimento , Coloração e RotulagemRESUMO
In human sperm, a fraction of its chromatin retains nucleosomes that are positioned on specific sequences containing genes and regulatory units essential for embryonic development. This nucleosome positioning (NP) feature provides an inherited epigenetic mark for sperm. However, it is not known whether there is a structural constraint for these nucleosomes and, if so, how they are localized in a three-dimensional (3D) context of the sperm nucleus. In this study, we examine the 3D organization of sperm chromatin and specifically determine its 3D localization of nucleosomes using structured illumination microscopy. A fraction of the sperm chromatin form nucleosome domains (NDs), visible as microscopic puncta ranging from 40â µm to 700â µm in diameter, and these NDs are precisely localized in the post acrosome region (PAR), outside the sperm's core chromatin. Further, NDs exist mainly in sperm from fertile men in a pilot survey with a small sample size. Together, this study uncovers a new spatially-restricted sub-nuclear structure containing NDs that are consistent with NPs of the sperm, which might represent a novel mark for healthy sperm in human.
RESUMO
Fertilization requires decondensation of promatine-condensed sperm chromatin, a dynamic process serving as an attractive system for the study of chromatin reprogramming. Nucleoplasmin is a key factor in regulating nucleosome assembly as a chaperone during fertilization process. However, knowledge on nucleoplasmin in chromatin formation remains elusive. Herein, magnetic tweezers (MT) and a chromatin assembly system were used to study the nucleoplasmin-mediated DNA decondensation/condensation at the single-molecular level in vitro. We found that protamine induces DNA condensation in a stepwise manner. Once DNA was condensed, nucleoplasmin, polyglutamic acid, and RNA could remove protamine from the DNA at different rates. The affinity binding of the different polyanions with protamine suggests chaperone-mediated chromatin decondensation activity occurs through protein-protein interactions. After decondensation, both RNA and polyglutamic acid prevented the transfer of histones onto the naked DNA. In contrast, nucleoplasmin is able to assist the histone transfer process, even though it carries the same negative charge as RNA and polyglutamic acid. These observations imply that the chaperone effects of nucleoplasmin during the decondensation/condensation process may be driven by specific spatial configuration of its acidic pentamer structure, rather than by electrostatic interaction. Our findings offer a novel molecular understanding of nucleoplasmin in sperm chromatin decondensation and subsequent developmental chromatin reprogramming at individual molecular level.
Assuntos
DNA/química , Nucleoplasminas/metabolismo , Animais , DNA/metabolismo , Histonas/metabolismo , Cinética , Ácido Poliglutâmico/metabolismo , Protaminas/metabolismo , RNA/metabolismo , Ressonância de Plasmônio de Superfície , Xenopus laevisRESUMO
Compelling evidence indicates that stress in utero, as manifested by low birth weight (LBW), increases the risk of metabolic syndrome in adulthood. Singletons conceived by assisted reproductive technology (ART) display a significant increase in LBW risk and ART offspring have a different metabolic profile starting at birth. Here, used mouse as a model, we found that ART resulted in reduced fetal weight and placental overgrowth at embryonic day 18.5 (E18.5). The ART placentae exhibited histomorphological alterations with defects in placental layer segregation and glycogen cells migration at E18.5. Further, ART treatments resulted in downregulation of a majority of placental nutrient transporters and reduction in placental efficiency. Moreover, the ART placentae were associated with increased methylation levels at imprinting control regions of H19, KvDMR1 and disrupted expression of a majority of imprinted genes important for placental development and function at E18.5. Our results from the mouse model show the first piece of evidence that ART treatment could affect fetal growth by disrupting placental development and function, suggests that perturbation of genomic imprinting resulted from embryo manipulation may contribute to these problems.
Assuntos
Peso Fetal , Feto/metabolismo , Doenças Placentárias/metabolismo , Placentação , Técnicas de Reprodução Assistida/efeitos adversos , Animais , Feminino , Feto/patologia , Camundongos , Placenta , Doenças Placentárias/genética , Doenças Placentárias/patologia , GravidezRESUMO
Tumor initiation and growth depend on its microenvironment in which cancer-associated fibroblasts (CAFs) in tumor stroma play an important role. Prostaglandin E2 (PGE2) and interleukin (IL)-6 signal pathways are involved in the crosstalk between tumor and stromal cells. However, how PGE2-mediated signaling modulates this crosstalk remains unclear. Here, we show that microRNA (miR)-149 links PGE2 and IL-6 signaling in mediating the crosstalk between tumor cells and CAFs in gastric cancer (GC). miR-149 inhibited fibroblast activation by targeting IL-6 and miR-149 expression was substantially suppressed in the CAFs of GC. miR-149 negatively regulated CAFs and their effect on GC development both in vitro and in vivo. CAFs enhanced epithelial-to-mesenchymal transition (EMT) and the stem-like properties of GC cells in a miR-149-IL-6-dependent manner. In addition to IL-6, PGE2 receptor 2 (PTGER2/EP2) was revealed as another potential target of miR-149 in fibroblasts. Furthermore, H. pylori infection, a leading cause of human GC, was able to induce cyclooxygenase-2 (COX-2)/PGE2 signaling and to enhance PGE2 production, resulting in the hypermethylation of miR-149 in CAFs and increased IL-6 secretion. Our findings indicate that miR-149 mediates the crosstalk between tumor cells and CAFs in GC and highlight the potential of interfering miRNAs in stromal cells to improve cancer therapy.
Assuntos
Dinoprostona/metabolismo , Epigênese Genética/genética , Fibroblastos/metabolismo , Interleucina-6/metabolismo , MicroRNAs/metabolismo , Linhagem Celular , Ciclo-Oxigenase 2/genética , Ciclo-Oxigenase 2/metabolismo , Fibroblastos/enzimologia , Helicobacter pylori/patogenicidade , Humanos , Transdução de Sinais/genética , Transdução de Sinais/fisiologiaRESUMO
Some of Xenopus ferritin cDNA family genes have already been sequenced. In this study, we report that two ferritin cDNA genes have been cloned from the Xenopus laevis germinal vesicle (GV) oocytes. The deduced proteins have different lengths with varied sequences when compared with the published Xenopus ferritins. One of them is the ferritin light chain homologous (LCH), which is reported for the first time in Xenopus and the other is the ferritin heavy chain homologous (HCH) that is first reported in Xenopus GV oocyte.
Assuntos
Ferritinas/genética , Oócitos/química , Xenopus laevis/genética , Animais , Sequência de Bases , Primers do DNA , DNA Complementar/genética , Feminino , Dados de Sequência Molecular , Alinhamento de Sequência , Análise de Sequência de DNARESUMO
Southern blotting is a common method used for the study of gene organization. Current methods of DNA transfer for Southern blotting, however, can be inefficient for high concentration agarose gels. Here, we report a method for high-performance Southern blotting of short DNA fragments such as nucleosomal DNAs by using a discontinuous agarose zone gel. The results show that sharp and well-resolved fractionation of short DNA fragments comparable to that from a high-concentration agarose gel could be obtained using a low-concentration agarose gel with a small zone of high-concentration agarose, and that the resulting DNA transfer is highly efficient and rapid.
Assuntos
Southern Blotting/métodos , DNA/análise , DNA/genética , Eletroforese em Gel de Ágar/métodos , Animais , Camundongos , Camundongos Endogâmicos C57BL , Nucleossomos/metabolismoRESUMO
Modulation on the duration of intracellular Ca(2+) transients is essential for B-cell activation. We have previously shown that extracellular-signal-regulated kinase (ERK) can phosphorylate inositol 1,4,5-trisphosphate receptor type 1 (IP(3)R1) at serine 436 and regulate its calcium channel activity. Here we investigate the potential physiological interaction between ERK and IP(3)R1 using chicken DT40 B-cell line in which different mutants are expressed. The interaction between ERK and IP(3)R1 is confirmed by co-immunoprecipitation and fluorescence resonance energy transfer (FRET) assays. This constitutive interaction is independent of either ERK kinase activation or IP(3)R1 phosphorylation status. Back phosphorylation analysis further shows that type 1 IP(3)R (IP(3)R1) is phosphorylated by ERK in anti-IgM-activated DT40 cells. Finally, our data show that the phosphorylation of Ser 436 in the IP(3)-binding domain of IP(3)R1 leads to less Ca(2+) release from endoplasmic reticulum (ER) microsomes and accelerates the declining of calcium increase in DT40 cells in response to anti-IgM stimulation.
Assuntos
Linfócitos B/metabolismo , Sinalização do Cálcio/fisiologia , Cálcio/metabolismo , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Animais , Sítios de Ligação , Linhagem Celular , Galinhas , Retroalimentação/fisiologia , Cinética , Fosforilação , Ligação ProteicaRESUMO
Type 1 inositol 1,4,5-trisphosphate receptor (IP(3)R1) is a widely expressed intracellular calcium-release channel found in many cell types. The operation of IP(3)R1 is regulated through phosphorylation by multiple protein kinases. Extracellular signal-regulated kinase (ERK) has been found involved in calcium signaling in distinct cell types, but the underlying mechanisms remain unclear. Here, we present evidence that ERK1/2 and IP(3)R1 bind together through an ERK binding motif in mouse cerebellum in vivo as well as in vitro. ERK-phosphorylating serines (Ser 436) was identified in mouse IP(3)R1 and Ser 436 phosphorylation had a suppressive effect on IP(3) binding to the recombinant N-terminal 604-amino acid residues (N604). Moreover, phosphorylation of Ser 436 in R(224-604) evidently enhance its interaction with the N-terminal "suppressor" region (N223). At last, our data showed that Ser 436 phosphorylation in IP(3)R1 decreased Ca(2+) releasing through IP(3)R1 channels.
Assuntos
Canais de Cálcio/metabolismo , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo , Sequência de Aminoácidos , Animais , Sítios de Ligação , Cálcio/metabolismo , Canais de Cálcio/química , Receptores de Inositol 1,4,5-Trifosfato , Camundongos , Microssomos/metabolismo , Dados de Sequência Molecular , Fosforilação , Estrutura Terciária de Proteína , Receptores Citoplasmáticos e Nucleares/química , Serina/metabolismoRESUMO
BACKGROUND: [corrected] Transferring a germinal vesicle (GV) from an aged woman's oocyte into ooplasm from a younger woman has been proposed as a possible way to overcome the problem of age-related decline in female fertility. Here we assessed this possibility by determining whether ooplasts derived from young mice could rescue ageing-associated chromosome misalignment in meiosis of oocytes from aged mice. METHODS: Three groups of reconstructed oocytes, young GV-young cytoplast (group YY), aged GV-young cytoplast (group AY), and young GV-aged cytoplast (group YA), were created by micromanipulation and electrofusion. RESULTS: Nuclear transplantation was successful in 89.8-94.4% of GV-ooplast complexes, and maturation rate of the reconstructed oocytes was 93.5-97.9%. Confocal microscopy analysis showed a significantly higher rate (49.2%) of chromosome misalignment in ageing mice than in young mice (16.9%), and 57.1% of oocytes in group AY exhibited chromosome misalignment, while the abnormality rate in groups YY and YA was 16.3 and 16.7% respectively. Calcium imaging showed that the three groups of reconstructed oocytes exhibited a similar pattern of calcium oscillations upon stimulation with bovine sperm extracts. Fertilization rate and developmental capacity to 2-cell embryos were also similar among the three groups of oocytes. CONCLUSIONS: Our findings suggest that: (i) the ooplasm from young mice could not rescue ageing-associated chromosome misalignment in meiosis of GV from aged mice; and (ii) behaviour of chromosome alignment over metaphase spindle is predominantly determined by GV material.
Assuntos
Cromossomos/genética , Meiose , Oócitos/fisiologia , Fatores Etários , Animais , Sinalização do Cálcio , Núcleo Celular/genética , Transplante de Células/métodos , Aberrações Cromossômicas , Feminino , Fertilização in vitro/métodos , Camundongos , Camundongos Endogâmicos , Oócitos/citologia , Fuso Acromático/genética , Fuso Acromático/fisiologiaRESUMO
BACKGROUND: This study examined the effect of nucleocytoplasmic ratio of fully grown germinal vesicle (GV) oocytes on meiotic chromosome segregation and alignment, spindle shape, Ca(2+) oscillations and capacity of early embryonic development in mouse. METHODS: GV oocytes with reduced volume (equal to 1/5 to 4/5 of an intact oocyte) were made by micromanipulation to remove different amounts of cytoplasm, and then matured and fertilized in vitro. RESULTS: When >1/2 of GV oocyte cytoplasm was removed, the time-course of GV breakdown (GVBD) was delayed and oocyte maturation rate decreased significantly. Abnormal chromosome segregation rate increased if >1/2 of the cytoplasm was removed from the oocyte. Length and structure of meiotic spindle and chromosome alignment were also impaired by the reduction of cytoplasmic volume. Once matured in vitro, the oocytes could undergo Sr(2+)-induced Ca(2+) oscillations and form pronuclei in a manner independent of nucleocytoplasmic ratio, but their ability to develop to 2-cell embryos was affected if >1/2 of their cytoplasm was removed from the GV oocytes. CONCLUSIONS: These results suggest that nucleocytoplasmic ratio is essential for normal meiotic chromosome segregation, spindle formation and chromosome alignment over the metaphase spindle, and development to 2-cell stage, for which 1/2 of the volume of the GV oocyte appears to be a threshold.
Assuntos
Núcleo Celular/metabolismo , Cromossomos/ultraestrutura , Citoplasma/metabolismo , Embrião de Mamíferos/fisiologia , Desenvolvimento Embrionário , Oócitos/metabolismo , Oócitos/fisiologia , Animais , Cálcio/metabolismo , Citogenética/métodos , Feminino , Fertilização , Fertilização in vitro , Meiose , Camundongos , Oscilometria , Fuso Acromático , Estrôncio/metabolismo , Fatores de TempoRESUMO
Mammalian freeze-dried sperm can maintain their genetic integrity and event support full development to term when microinjected into mature oocytes. However, it is unknown whether freeze-dried sperm can still maintain their calcium oscillation-inducing capability. Here, we microinjected mouse and bovine freeze-dried sperm into mouse MII oocytes and examined their calcium oscillation-inducing ability following intracytoplasmic sperm injection (ICSI). Two pieces of information are revealed. First, nearly all oocytes injected with a freeze-dried mouse sperm head or a bovine sperm showed fertilization-like calcium oscillations, indicating that freeze-drying treatment does not affect the activity of the sperm factor responsible for calcium oscillations. Second, freeze-dried sperm exhibited high resistance to external temperature increase. This is shown by the finding that the freeze-dried sperm can maintain their calcium oscillation-inducing capacity even following exposure to 100 degrees C for 3 h. We therefore conclude that mammalian sperm can maintain their calcium oscillation-inducing capability following freeze-drying, rehydration, and ICSI treatments.
Assuntos
Sinalização do Cálcio/fisiologia , Criopreservação/métodos , Oócitos/fisiologia , Preservação do Sêmen/métodos , Injeções de Esperma Intracitoplásmicas/métodos , Espermatozoides/metabolismo , Espermatozoides/transplante , Animais , Bovinos , Linhagem Celular , Células Cultivadas , Masculino , Camundongos , MicroinjeçõesRESUMO
BACKGROUND: Sr2+ is the most efficient agent for mouse oocyte activation and functions by inducing Ca2+ oscillations. However, its specific mechanism of action remains unknown. Here we investigated the specificity and possible mechanism of Sr2+-induced Ca2+ oscillations in mouse oocytes and early embryos. METHODS: Ca2+ oscillations in oocytes and embryos were measured by ratiometric fluorescence imaging using fura-2AM. The role of phospholipase C (PLC) and inositol trisphosphate (InsP3) receptors in Sr2+-induced Ca2+ oscillations was examined by selective inhibitors. RESULTS: Sr2+ can induce Ca2+ oscillations in both immature and mature oocytes, and in early embryos. A cell cycle stage-dependent phenomenon to Sr2+ stimulation was observed in 1-cell embryos. By using a low molecular weight heparin to antagonize the function of InsP3 receptors, we were able to show that InsP3 receptors are essential for Sr2+-induced Ca2+ oscillations. Treating metaphase II (MII) oocytes with the PLC inhibitor, U73122, abolished Sr2+-induced increases in Ca2+. This inhibitory effect of U73122 could be rescued by microinjection of InsP3, indicating that Sr2+-induced Ca2+ oscillations require the synergistic action of InsP3. CONCLUSIONS: Sr2+-induced calcium oscillations in mouse oocytes and early embryos are mediated through InsP3 receptors, and require PLC activation and the synergistic action of InsP3.
Assuntos
Cálcio/metabolismo , Inositol 1,4,5-Trifosfato/fisiologia , Oócitos/efeitos dos fármacos , Estrôncio/farmacologia , Animais , Canais de Cálcio/efeitos dos fármacos , Canais de Cálcio/fisiologia , Sinalização do Cálcio/fisiologia , Sinergismo Farmacológico , Embrião de Mamíferos/metabolismo , Desenvolvimento Embrionário/efeitos dos fármacos , Ativação Enzimática , Estrenos/farmacologia , Feminino , Heparina/farmacologia , Receptores de Inositol 1,4,5-Trifosfato , Masculino , Meiose , Camundongos , Oócitos/fisiologia , Partenogênese , Pirrolidinonas/farmacologia , Receptores Citoplasmáticos e Nucleares/efeitos dos fármacos , Receptores Citoplasmáticos e Nucleares/fisiologia , Espermatozoides/fisiologia , Fosfolipases Tipo C/antagonistas & inibidores , Fosfolipases Tipo C/metabolismoRESUMO
It has been shown recently that hyperplasia suppressor gene (HSG) is a powerful regulator for cell proliferation and has a critical role in mitochondrial fusion in many cells. However, little is known about its expression, localization, and function during oocyte maturation and early embryogenesis. In this study, with indirect immunofluorescent staining and Western blotting, we found that HSG was expressed in mouse oocytes and preimplantation embryos which primarily exhibited a submembrane distribution pattern in the cytoplasm. Moreover, HSG mainly associated with beta-tubulin during oocyte maturation and early embryonic development. When mouse zygotes were injected with HSG antisense plasmid and cultured in vitro, their capacity to form blastocysts was severely impaired. Our results indicate that HSG plays an essential role in mouse preimplantation development.