Limits...
Regulation of meiotic prophase arrest in mouse oocytes by GPR3, a constitutive activator of the Gs G protein.

Freudzon L, Norris RP, Hand AR, Tanaka S, Saeki Y, Jones TL, Rasenick MM, Berlot CH, Mehlmann LM, Jaffe LA - J. Cell Biol. (2005)

Bottom Line: GPR3 decreased the ratio of Galpha(s) in the oocyte plasma membrane versus the cytoplasm and also decreased the amount of Galpha(s) in the oocyte.However, GPR3-dependent G(s) activity was similar in follicle-enclosed and follicle-free oocytes.Thus, the maintenance of prophase arrest depends on the constitutive activity of GPR3 in the oocyte, and the follicle cell signal acts by a means other than increasing GPR3 activity.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06032.

ABSTRACT
The arrest of meiotic prophase in mouse oocytes within antral follicles requires the G protein G(s) and an orphan member of the G protein-coupled receptor family, GPR3. To determine whether GPR3 activates G(s), the localization of Galpha(s) in follicle-enclosed oocytes from Gpr3(+/+) and Gpr3(-/-) mice was compared by using immunofluorescence and Galpha(s)GFP. GPR3 decreased the ratio of Galpha(s) in the oocyte plasma membrane versus the cytoplasm and also decreased the amount of Galpha(s) in the oocyte. Both of these properties indicate that GPR3 activates G(s). The follicle cells around the oocyte are also necessary to keep the oocyte in prophase, suggesting that they might activate GPR3. However, GPR3-dependent G(s) activity was similar in follicle-enclosed and follicle-free oocytes. Thus, the maintenance of prophase arrest depends on the constitutive activity of GPR3 in the oocyte, and the follicle cell signal acts by a means other than increasing GPR3 activity.

Show MeSH

Related in: MedlinePlus

Determination of the optical correction factor for comparing the plasma membrane-to-cytoplasm fluorescence ratios in preantral follicle-enclosed and isolated oocytes. (A) Diagram of the optical difference in comparing follicle-enclosed with isolated oocytes. (B) YFP-Mem and YFP fluorescence from an oocyte in a preantral follicle. (C) YFP-Mem and YFP fluorescence from the same oocyte as shown in B after isolation from its follicle. The detector gain for B was 3.2 times that for C, reflecting the fact that the fluorescence intensity collected from an oocyte inside a preantral follicle is less than that collected from an isolated oocyte. Other confocal microscope settings and bars were the same for B and C. The plasma membrane-to-cytoplasm fluorescence ratio that was measured for B was 3.5 and that for C was 8.2. Based on measurements of 14 such oocytes, removal from the follicle resulted in an increase in the apparent plasma membrane-to-cytoplasm fluorescence ratio of 2.2 ± 0.2 (mean ± SEM); data from two mice.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2171177&req=5

fig7: Determination of the optical correction factor for comparing the plasma membrane-to-cytoplasm fluorescence ratios in preantral follicle-enclosed and isolated oocytes. (A) Diagram of the optical difference in comparing follicle-enclosed with isolated oocytes. (B) YFP-Mem and YFP fluorescence from an oocyte in a preantral follicle. (C) YFP-Mem and YFP fluorescence from the same oocyte as shown in B after isolation from its follicle. The detector gain for B was 3.2 times that for C, reflecting the fact that the fluorescence intensity collected from an oocyte inside a preantral follicle is less than that collected from an isolated oocyte. Other confocal microscope settings and bars were the same for B and C. The plasma membrane-to-cytoplasm fluorescence ratio that was measured for B was 3.5 and that for C was 8.2. Based on measurements of 14 such oocytes, removal from the follicle resulted in an increase in the apparent plasma membrane-to-cytoplasm fluorescence ratio of 2.2 ± 0.2 (mean ± SEM); data from two mice.

Mentions: Second and third columns indicate the ratios of plasma membrane GαsGFP fluorescence (PM) to cytoplasm GαsGFP fluorescence (CYTO) in the oocyte. Mean ± SEM (n = number of oocytes). Data for follicle-enclosed oocytes are from three mice of each genotype, and data for isolated oocytes are from two mice of each genotype. For each row, the last column indicates the value listed in the third column divided by the value listed in the second column. See the last section of Results and Fig. 7 for an explanation of the optical correction.


Regulation of meiotic prophase arrest in mouse oocytes by GPR3, a constitutive activator of the Gs G protein.

Freudzon L, Norris RP, Hand AR, Tanaka S, Saeki Y, Jones TL, Rasenick MM, Berlot CH, Mehlmann LM, Jaffe LA - J. Cell Biol. (2005)

Determination of the optical correction factor for comparing the plasma membrane-to-cytoplasm fluorescence ratios in preantral follicle-enclosed and isolated oocytes. (A) Diagram of the optical difference in comparing follicle-enclosed with isolated oocytes. (B) YFP-Mem and YFP fluorescence from an oocyte in a preantral follicle. (C) YFP-Mem and YFP fluorescence from the same oocyte as shown in B after isolation from its follicle. The detector gain for B was 3.2 times that for C, reflecting the fact that the fluorescence intensity collected from an oocyte inside a preantral follicle is less than that collected from an isolated oocyte. Other confocal microscope settings and bars were the same for B and C. The plasma membrane-to-cytoplasm fluorescence ratio that was measured for B was 3.5 and that for C was 8.2. Based on measurements of 14 such oocytes, removal from the follicle resulted in an increase in the apparent plasma membrane-to-cytoplasm fluorescence ratio of 2.2 ± 0.2 (mean ± SEM); data from two mice.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2171177&req=5

fig7: Determination of the optical correction factor for comparing the plasma membrane-to-cytoplasm fluorescence ratios in preantral follicle-enclosed and isolated oocytes. (A) Diagram of the optical difference in comparing follicle-enclosed with isolated oocytes. (B) YFP-Mem and YFP fluorescence from an oocyte in a preantral follicle. (C) YFP-Mem and YFP fluorescence from the same oocyte as shown in B after isolation from its follicle. The detector gain for B was 3.2 times that for C, reflecting the fact that the fluorescence intensity collected from an oocyte inside a preantral follicle is less than that collected from an isolated oocyte. Other confocal microscope settings and bars were the same for B and C. The plasma membrane-to-cytoplasm fluorescence ratio that was measured for B was 3.5 and that for C was 8.2. Based on measurements of 14 such oocytes, removal from the follicle resulted in an increase in the apparent plasma membrane-to-cytoplasm fluorescence ratio of 2.2 ± 0.2 (mean ± SEM); data from two mice.
Mentions: Second and third columns indicate the ratios of plasma membrane GαsGFP fluorescence (PM) to cytoplasm GαsGFP fluorescence (CYTO) in the oocyte. Mean ± SEM (n = number of oocytes). Data for follicle-enclosed oocytes are from three mice of each genotype, and data for isolated oocytes are from two mice of each genotype. For each row, the last column indicates the value listed in the third column divided by the value listed in the second column. See the last section of Results and Fig. 7 for an explanation of the optical correction.

Bottom Line: GPR3 decreased the ratio of Galpha(s) in the oocyte plasma membrane versus the cytoplasm and also decreased the amount of Galpha(s) in the oocyte.However, GPR3-dependent G(s) activity was similar in follicle-enclosed and follicle-free oocytes.Thus, the maintenance of prophase arrest depends on the constitutive activity of GPR3 in the oocyte, and the follicle cell signal acts by a means other than increasing GPR3 activity.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 06032.

ABSTRACT
The arrest of meiotic prophase in mouse oocytes within antral follicles requires the G protein G(s) and an orphan member of the G protein-coupled receptor family, GPR3. To determine whether GPR3 activates G(s), the localization of Galpha(s) in follicle-enclosed oocytes from Gpr3(+/+) and Gpr3(-/-) mice was compared by using immunofluorescence and Galpha(s)GFP. GPR3 decreased the ratio of Galpha(s) in the oocyte plasma membrane versus the cytoplasm and also decreased the amount of Galpha(s) in the oocyte. Both of these properties indicate that GPR3 activates G(s). The follicle cells around the oocyte are also necessary to keep the oocyte in prophase, suggesting that they might activate GPR3. However, GPR3-dependent G(s) activity was similar in follicle-enclosed and follicle-free oocytes. Thus, the maintenance of prophase arrest depends on the constitutive activity of GPR3 in the oocyte, and the follicle cell signal acts by a means other than increasing GPR3 activity.

Show MeSH
Related in: MedlinePlus