Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Comparative Study
. 2007 Aug;117(8):2186-96.
doi: 10.1172/JCI30398.

Shared signaling networks active in B cells isolated from genetically distinct mouse models of lupus

Tianfu Wu  1 , Xiangmei Qin, Zoran Kurepa, Kirthi Raman Kumar, Kui Liu, Hasna Kanta, Xin J Zhou, Anne B Satterthwaite, Laurie S Davis, Chandra Mohan
Affiliations
Comparative Study

Shared signaling networks active in B cells isolated from genetically distinct mouse models of lupus

Tianfu Wu et al. J Clin Invest. 2007 Aug.

Abstract

Though B cells play key roles in lupus pathogenesis, the molecular circuitry and its dysregulation in these cells as disease evolves remain poorly understood. To address this, a comprehensive scan of multiple signaling axes using multiplexed Western blotting was undertaken in several different murine lupus strains. PI3K/AKT/mTOR (mTOR, mammalian target of rapamycin), MEK1/Erk1/2, p38, NF-kappaB, multiple Bcl-2 family members, and cell-cycle molecules were observed to be hyperexpressed in lupus B cells in an age-dependent and lupus susceptibility gene-dose-dependent manner. Therapeutic targeting of the AKT/mTOR axis using a rapamycin (sirolimus) derivative ameliorated the serological, cellular, and pathological phenotypes associated with lupus. Surprisingly, the targeting of this axis was associated with the crippling of several other signaling axes. These studies reveal that lupus pathogenesis is contingent upon the activation of an elaborate network of signaling cascades that is shared among genetically distinct mouse models and raise hope that targeting pivotal nodes in these networks may offer therapeutic benefit.

PubMed Disclaimer

Figures

Figure 1
Figure 1. Activation status of AKT/mTOR axis in lupus B cells.
Anti-B220 bead-purified splenic B cells were isolated from 2-month-old female B6, B6.Sle1z, and B6.Sle1z.Sle3z mice, anti-IgM F(ab′)2 stimulated, lysed, electrophoresed, and blotted using a panel of antibodies specific for various molecules in the AKT/mTOR axis, some of which were specific for the phosphorylated forms of the signaling molecules. The mean (± SEM) values of 3–6 individual samples (derived from independent mice) are plotted on the right The P values shown pertain to a Student’s t test comparison of the 24-hour–stimulated (or unstimulated) congenic samples with the corresponding stimulated (or unstimulated) B6 samples, respectively. *P < 0.05; **P < 0.01; ***P < 0.001.
Figure 2
Figure 2. Activation status of Ras/MEK1/Erk1/2 pathway in lupus B cells.
Legend is as noted for Figure 1, except that various molecules in the Ras/MEK1/Erk1/2 axis were specifically examined. *P < 0.05; **P < 0.01; ***P < 0.001.
Figure 3
Figure 3. Activation status of NF-κB pathway in lupus B cells.
Legend is as noted for Figure 1, except that various molecules in the NF-κΒ axis were specifically examined. *P < 0.05; **P < 0.01; ***P < 0.001.
Figure 4
Figure 4. Bcl-2 family members in lupus B cells.
Legend is as noted for Figure 1, except that various molecules in the Bcl-2 family were specifically examined. *P < 0.05; **P < 0.01; ***P < 0.001.
Figure 5
Figure 5. Cell-cycle proteins and other signaling axes in lupus B cells.
Legend is as noted for Figure 1, except that cell cycle proteins were specifically examined. *P < 0.05; **P < 0.01; ***P < 0.001.
Figure 6
Figure 6. Activation status of JAK/STAT molecules in lupus B cells.
Legend is as noted for Figure 1, except that various molecules in the JAK/STAT axis as well as CAMK II and PKCα were specifically examined. *P < 0.05; **P < 0.01; ***P < 0.001.
Figure 7
Figure 7. Activation status of AKT and Erk1/2 in total splenic B cells and resting follicular B cells.
Anti-B220 bead-purified splenic B cells (A) and purified follicular splenic B cells obtained by flow cytometry–based cell-sorting (B) were isolated from 2-month-old female B6 and B6.Sle1z mice. Following an initial stimulation with a lower concentration of anti-IgM F(ab′)2 (1 μg/ml) for 48 hours, cells were either immediately lysed or were reexposed to a higher concentration of anti-IgM F(ab′)2 (10 μg/ml) for 5 minutes or 24 hours and then lysed. Lysates were electrophoresed and blotted using antibodies against the total or phosphorylated forms of AKT and Erk1/2. The mean band intensity values as analyzed by ImageJ are indicated below each band.
Figure 8
Figure 8. Status of selected signaling pathways in other lupus models.
Anti-B220 bead-purified splenic B cells were isolated from female B6, male BXSB, and female MRL/lpr mice, aged 2–3 months, lysed (without deliberate BCR cross-linking), electrophoresed, and blotted using a panel of antibodies targeted to the indicated signaling molecules, some of which were specific for the phosphorylated forms of the signaling molecule, as noted. The P values shown pertain to a Student’s t test comparison of the BXSB or MRL/lpr values with the B6 value. *P < 0.05; **P < 0.01; ***P < 0.001.
Figure 9
Figure 9. Impact of mTOR blockade on B6.Sle1z.Sle3z lupus.
Shown are changes in spleen weight (A), total splenocyte counts (B), percentage change in the numbers of different splenic cell subsets (C), anti-nuclear autoantibodies as determined by ELISA (D–G), proteinuria (H), blood urea nitrogen (BUN) (I), and kidney pathology (J). GN, glomerulonephritis; P, placebo; R, RAD001; d, days after treatment. P values shown pertain to a Student’s t test comparison of the RAD001-treated congenic samples with the placebo-treated congenic samples.
Figure 10
Figure 10. mTOR blockade dampens multiple signaling axes in lupus.
Anti-B220 bead-purified splenic B cells were isolated from 4-month-old female B6.Sle1z.Sle3z mice (treated with RAD001 or placebo), lysed, electrophoresed, and blotted using a panel of antibodies targeted to the indicated signaling molecules, some of which were specific for the phosphorylated forms of the signaling molecules, as noted. P values shown pertain to a Student’s t test comparison of the RAD001-treated congenic samples with the placebo-treated congenic samples. *P < 0.05; **P < 0.01; ***P < 0.001.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Kotzin B.L. Systemic lupus erythematosus. Cell. 1996;85:303–306. - PubMed
    1. Lipsky P.E. Systemic lupus erythematosus: an autoimmune disease of B cell hyperactivity. Nat. Immunol. . 2001;2:764–766. - PubMed
    1. Mohan C., Morel L., Yang P., Wakeland E.K. Genetic dissection of systemic lupus erythematosus pathogenesis: Sle2 on murine chromosome 4 leads to B cell hyperactivity. J. Immunol. 1997;159:454–465. - PubMed
    1. Klinman D.M. Polyclonal B cell activation in lupus-prone mice precedes and predicts the development of autoimmune disease. J. Clin. Invest. . 1990;86:1249–1254. - PMC - PubMed
    1. Haraldsson M.K., et al. Autoimmune alterations induced by the New Zealand Black Lbw2 locus in BWF1 mice. J. Immunol. 2005;174:5065–5073. - PubMed

Publication types

MeSH terms