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Variations in Gnai2 and Rgs1 expression affect chemokine receptor signaling and the organization of secondary lymphoid organs.

Hwang IY, Park C, Harrision KA, Huang NN, Kehrl JH - Genes Immun. (2010)

Bottom Line: Examination of B cells from mice with varying numbers of intact alleles of Ccr7, Rgs1, Gnai2, and Gnai3 provided the basis for these results.Loss of a single allele of either Gnai2 or Rgs1 affected CCL19 triggered chemotaxis, whereas the loss of a single allele of Ccr7, which encodes the cognate CCL19 receptor, had little effect.Emphasizing the importance of Gnai2, B cells lacking Gnai3 expression responded to chemokines better than did wild-type B cells.

View Article: PubMed Central - PubMed

Affiliation: B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.

ABSTRACT
Ligand bound chemoattractant receptors activate the heterotrimeric G-protein G(i) to stimulate downstream signaling pathways to properly position lymphocytes in lymphoid organs. Here, we show how variations in the expression of a chemokine receptor and in two components in the signaling pathway, Galpha(i2) and RGS1, affect the output fidelity of the signaling pathway. Examination of B cells from mice with varying numbers of intact alleles of Ccr7, Rgs1, Gnai2, and Gnai3 provided the basis for these results. Loss of a single allele of either Gnai2 or Rgs1 affected CCL19 triggered chemotaxis, whereas the loss of a single allele of Ccr7, which encodes the cognate CCL19 receptor, had little effect. Emphasizing the importance of Gnai2, B cells lacking Gnai3 expression responded to chemokines better than did wild-type B cells. At an organismal level, variations in Rgs1 and Gnai2 expression affected marginal zone B-cell development, splenic architecture, lymphoid follicle size, and germinal center morphology. Gnai2 expression was also needed for the proper alignment of MOMA-1(+) macrophages and MAdCAM-1(+) endothelial cells along marginal zone sinuses in the spleen. These data indicate that chemoattractant receptors, heterotrimeric G-proteins, and RGS protein expression levels have a complex interrelationship that affects the responses to chemoattractant exposure.

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Intercross of Rgs1+/− and Gnai2+/− mice. Photographs of representative wild type, Gnai2−/−, and Rgs1−/−/Gnai2−/− C57/BL6 mice. The result of genotyping mice from double heterozygote crosses is shown below the photographs. The percentage of each of the different genotypes is shown and in parentheses the predicted frequency of the genotype. The results are from genotyping 342 mice. The p values are significantly different for each observed genotype number vs. expected genotype number (P< 0.001 by chi-square tests).
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Figure 1: Intercross of Rgs1+/− and Gnai2+/− mice. Photographs of representative wild type, Gnai2−/−, and Rgs1−/−/Gnai2−/− C57/BL6 mice. The result of genotyping mice from double heterozygote crosses is shown below the photographs. The percentage of each of the different genotypes is shown and in parentheses the predicted frequency of the genotype. The results are from genotyping 342 mice. The p values are significantly different for each observed genotype number vs. expected genotype number (P< 0.001 by chi-square tests).

Mentions: On a C57BL/6 background the Rgs1−/− mice bred and thrived similar to wild type mice while the Gnai2−/− mice bred poorly or not at all and were maintained as heterozygotes. Litters from heterozygotic crosses generated lower than expected numbers of Gnai2−/− mice. A previous study had reported that Gnai2+/− intercrosses produced 9.7% Gnai2−/− mice versus the expected 25%. A significant loss of Gnai2−/− mice was reported to occur perinatally.16 In our colony Gnai2−/− mice are smaller than their wild type littermates and often die prior to 6 months of age of varying causes. The Gnai3−/− mice we have used have been backcrossed 3–6 generations onto C57BL/6 background and have thrived normally. Double heterozygote crosses were bred to generate mice with the varying alleles of Rgs1 and Gnai2. The double knock-out mice exhibited the same smaller stature as did the Gnai2−/− mice (Figure 1). Analysis of the frequency of the different genotypes obtained from these crosses revealed an increased representation of the wild type Gnai2 allele in the offspring. The most over represented genotype among the mice was Rgs1+/−/Gnai2+/+ while the Rgs1 allele status had little effect on the survival of the mice lacking both Gnai2 alleles. There was also the suggestion that the lack of one allele of Gnai2 negatively impacted the survival of the mice.


Variations in Gnai2 and Rgs1 expression affect chemokine receptor signaling and the organization of secondary lymphoid organs.

Hwang IY, Park C, Harrision KA, Huang NN, Kehrl JH - Genes Immun. (2010)

Intercross of Rgs1+/− and Gnai2+/− mice. Photographs of representative wild type, Gnai2−/−, and Rgs1−/−/Gnai2−/− C57/BL6 mice. The result of genotyping mice from double heterozygote crosses is shown below the photographs. The percentage of each of the different genotypes is shown and in parentheses the predicted frequency of the genotype. The results are from genotyping 342 mice. The p values are significantly different for each observed genotype number vs. expected genotype number (P< 0.001 by chi-square tests).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2908210&req=5

Figure 1: Intercross of Rgs1+/− and Gnai2+/− mice. Photographs of representative wild type, Gnai2−/−, and Rgs1−/−/Gnai2−/− C57/BL6 mice. The result of genotyping mice from double heterozygote crosses is shown below the photographs. The percentage of each of the different genotypes is shown and in parentheses the predicted frequency of the genotype. The results are from genotyping 342 mice. The p values are significantly different for each observed genotype number vs. expected genotype number (P< 0.001 by chi-square tests).
Mentions: On a C57BL/6 background the Rgs1−/− mice bred and thrived similar to wild type mice while the Gnai2−/− mice bred poorly or not at all and were maintained as heterozygotes. Litters from heterozygotic crosses generated lower than expected numbers of Gnai2−/− mice. A previous study had reported that Gnai2+/− intercrosses produced 9.7% Gnai2−/− mice versus the expected 25%. A significant loss of Gnai2−/− mice was reported to occur perinatally.16 In our colony Gnai2−/− mice are smaller than their wild type littermates and often die prior to 6 months of age of varying causes. The Gnai3−/− mice we have used have been backcrossed 3–6 generations onto C57BL/6 background and have thrived normally. Double heterozygote crosses were bred to generate mice with the varying alleles of Rgs1 and Gnai2. The double knock-out mice exhibited the same smaller stature as did the Gnai2−/− mice (Figure 1). Analysis of the frequency of the different genotypes obtained from these crosses revealed an increased representation of the wild type Gnai2 allele in the offspring. The most over represented genotype among the mice was Rgs1+/−/Gnai2+/+ while the Rgs1 allele status had little effect on the survival of the mice lacking both Gnai2 alleles. There was also the suggestion that the lack of one allele of Gnai2 negatively impacted the survival of the mice.

Bottom Line: Examination of B cells from mice with varying numbers of intact alleles of Ccr7, Rgs1, Gnai2, and Gnai3 provided the basis for these results.Loss of a single allele of either Gnai2 or Rgs1 affected CCL19 triggered chemotaxis, whereas the loss of a single allele of Ccr7, which encodes the cognate CCL19 receptor, had little effect.Emphasizing the importance of Gnai2, B cells lacking Gnai3 expression responded to chemokines better than did wild-type B cells.

View Article: PubMed Central - PubMed

Affiliation: B-Cell Molecular Immunology Section, Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.

ABSTRACT
Ligand bound chemoattractant receptors activate the heterotrimeric G-protein G(i) to stimulate downstream signaling pathways to properly position lymphocytes in lymphoid organs. Here, we show how variations in the expression of a chemokine receptor and in two components in the signaling pathway, Galpha(i2) and RGS1, affect the output fidelity of the signaling pathway. Examination of B cells from mice with varying numbers of intact alleles of Ccr7, Rgs1, Gnai2, and Gnai3 provided the basis for these results. Loss of a single allele of either Gnai2 or Rgs1 affected CCL19 triggered chemotaxis, whereas the loss of a single allele of Ccr7, which encodes the cognate CCL19 receptor, had little effect. Emphasizing the importance of Gnai2, B cells lacking Gnai3 expression responded to chemokines better than did wild-type B cells. At an organismal level, variations in Rgs1 and Gnai2 expression affected marginal zone B-cell development, splenic architecture, lymphoid follicle size, and germinal center morphology. Gnai2 expression was also needed for the proper alignment of MOMA-1(+) macrophages and MAdCAM-1(+) endothelial cells along marginal zone sinuses in the spleen. These data indicate that chemoattractant receptors, heterotrimeric G-proteins, and RGS protein expression levels have a complex interrelationship that affects the responses to chemoattractant exposure.

Show MeSH
Related in: MedlinePlus