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LRRK1 is critical in the regulation of B-cell responses and CARMA1-dependent NF-κB activation.

Morimoto K, Baba Y, Shinohara H, Kang S, Nojima S, Kimura T, Ito D, Yoshida Y, Maeda Y, Sarashina-Kida H, Nishide M, Hosokawa T, Kato Y, Hayama Y, Kinehara Y, Okuno T, Takamatsu H, Hirano T, Shima Y, Narazaki M, Kurosaki T, Toyofuku T, Kumanogoh A - Sci Rep (2016)

Bottom Line: Concomitantly, B cells lacking LRRK1 exhibited a profound defect in proliferation and survival upon BCR stimulation, which correlated with impaired BCR-mediated NF-κB activation and reduced expression of NF-κB target genes including Bcl-xL, cyclin D2, and NFATc1/αA.Furthermore, LRRK1 physically interacted and potently synergized with CARMA1 to enhance NF-κB activation.Our results reveal a critical role of LRRK1 in NF-κB signaling in B cells and the humoral immune response.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunopathology, World Premier International (WPI) Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan.

ABSTRACT
B-cell receptor (BCR) signaling plays a critical role in B-cell activation and humoral immunity. In this study, we discovered a critical function of leucine-rich repeat kinase 1 (LRRK1) in BCR-mediated immune responses. Lrrk1(-/-) mice exhibited altered B1a-cell development and basal immunoglobulin production. In addition, these mice failed to produce IgG3 antibody in response to T cell-independent type 2 antigen due to defects in IgG3 class-switch recombination. Concomitantly, B cells lacking LRRK1 exhibited a profound defect in proliferation and survival upon BCR stimulation, which correlated with impaired BCR-mediated NF-κB activation and reduced expression of NF-κB target genes including Bcl-xL, cyclin D2, and NFATc1/αA. Furthermore, LRRK1 physically interacted and potently synergized with CARMA1 to enhance NF-κB activation. Our results reveal a critical role of LRRK1 in NF-κB signaling in B cells and the humoral immune response.

No MeSH data available.


Related in: MedlinePlus

LRRK1 is required for IgG3 germline transcription and AID expression in response to TI-2 antigen.(a) NP-binding B cells from spleen of wild-type and Lrrk1−/− mice 4 days after immunization with NP-Ficoll were detected by flow cytometric staining with NIP-APC. (b) NP-binding B cells per 106 splenocytes were counted based on (a). Data are presented as means ± s.d. for 5–6 mice. (c,d) Quantitative RT-PCR analysis of post-switch transcript (PST) of the μ chain I region and γ3-chain C region (Iμ-Cγ3), gremline transcripts (GLT) (Iμ-Cμ, Iγ3-Cγ3) (c), and AID (d) expression in CD19+ B cells 4 days after immunization with NP-Ficoll. Data are presented as means ± s.d. of two independent experiments. NS, not significant. *P < 0.05, **P < 0.01, ***P < 0.001 (two-tailed unpaired Student’s t-test).
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f3: LRRK1 is required for IgG3 germline transcription and AID expression in response to TI-2 antigen.(a) NP-binding B cells from spleen of wild-type and Lrrk1−/− mice 4 days after immunization with NP-Ficoll were detected by flow cytometric staining with NIP-APC. (b) NP-binding B cells per 106 splenocytes were counted based on (a). Data are presented as means ± s.d. for 5–6 mice. (c,d) Quantitative RT-PCR analysis of post-switch transcript (PST) of the μ chain I region and γ3-chain C region (Iμ-Cγ3), gremline transcripts (GLT) (Iμ-Cμ, Iγ3-Cγ3) (c), and AID (d) expression in CD19+ B cells 4 days after immunization with NP-Ficoll. Data are presented as means ± s.d. of two independent experiments. NS, not significant. *P < 0.05, **P < 0.01, ***P < 0.001 (two-tailed unpaired Student’s t-test).

Mentions: Because splenic MZ B cells rapidly and preferentially respond to TI-2 antigens to generate IgM and switched IgG antibodies, defects in TI-2–induced immunoglobulin class switch are often correlated with a numerical decrease or functional impairment of MZ B cells. Lrrk1−/− mice had sufficient numbers of MZ B cells, so we investigated whether antigen-specific B cells could respond to TI-2 antigen and elicit class-switch recombination (CSR) in the absence of LRRK1. To this end, we measured the frequency of NP-specific B cells in the spleen 4 days after the NP-Ficoll immunization. Wild-type mice exhibited a significant increase in NP-specific IgM+ and class-switched IgG3+ B cells, as assessed by flow cytometory with 4-hydroxy-5-indo-3-nitrophenyl acetyl (NIP)-APC (Fig. 3a,b). By contrast, Lrrk1−/− mice failed to generate NP-specific IgG3+ B cells and also exhibited a slight but statistically insignificant decrease in the number of NP-specific IgM+ cells (Fig. 3a,b).


LRRK1 is critical in the regulation of B-cell responses and CARMA1-dependent NF-κB activation.

Morimoto K, Baba Y, Shinohara H, Kang S, Nojima S, Kimura T, Ito D, Yoshida Y, Maeda Y, Sarashina-Kida H, Nishide M, Hosokawa T, Kato Y, Hayama Y, Kinehara Y, Okuno T, Takamatsu H, Hirano T, Shima Y, Narazaki M, Kurosaki T, Toyofuku T, Kumanogoh A - Sci Rep (2016)

LRRK1 is required for IgG3 germline transcription and AID expression in response to TI-2 antigen.(a) NP-binding B cells from spleen of wild-type and Lrrk1−/− mice 4 days after immunization with NP-Ficoll were detected by flow cytometric staining with NIP-APC. (b) NP-binding B cells per 106 splenocytes were counted based on (a). Data are presented as means ± s.d. for 5–6 mice. (c,d) Quantitative RT-PCR analysis of post-switch transcript (PST) of the μ chain I region and γ3-chain C region (Iμ-Cγ3), gremline transcripts (GLT) (Iμ-Cμ, Iγ3-Cγ3) (c), and AID (d) expression in CD19+ B cells 4 days after immunization with NP-Ficoll. Data are presented as means ± s.d. of two independent experiments. NS, not significant. *P < 0.05, **P < 0.01, ***P < 0.001 (two-tailed unpaired Student’s t-test).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4863158&req=5

f3: LRRK1 is required for IgG3 germline transcription and AID expression in response to TI-2 antigen.(a) NP-binding B cells from spleen of wild-type and Lrrk1−/− mice 4 days after immunization with NP-Ficoll were detected by flow cytometric staining with NIP-APC. (b) NP-binding B cells per 106 splenocytes were counted based on (a). Data are presented as means ± s.d. for 5–6 mice. (c,d) Quantitative RT-PCR analysis of post-switch transcript (PST) of the μ chain I region and γ3-chain C region (Iμ-Cγ3), gremline transcripts (GLT) (Iμ-Cμ, Iγ3-Cγ3) (c), and AID (d) expression in CD19+ B cells 4 days after immunization with NP-Ficoll. Data are presented as means ± s.d. of two independent experiments. NS, not significant. *P < 0.05, **P < 0.01, ***P < 0.001 (two-tailed unpaired Student’s t-test).
Mentions: Because splenic MZ B cells rapidly and preferentially respond to TI-2 antigens to generate IgM and switched IgG antibodies, defects in TI-2–induced immunoglobulin class switch are often correlated with a numerical decrease or functional impairment of MZ B cells. Lrrk1−/− mice had sufficient numbers of MZ B cells, so we investigated whether antigen-specific B cells could respond to TI-2 antigen and elicit class-switch recombination (CSR) in the absence of LRRK1. To this end, we measured the frequency of NP-specific B cells in the spleen 4 days after the NP-Ficoll immunization. Wild-type mice exhibited a significant increase in NP-specific IgM+ and class-switched IgG3+ B cells, as assessed by flow cytometory with 4-hydroxy-5-indo-3-nitrophenyl acetyl (NIP)-APC (Fig. 3a,b). By contrast, Lrrk1−/− mice failed to generate NP-specific IgG3+ B cells and also exhibited a slight but statistically insignificant decrease in the number of NP-specific IgM+ cells (Fig. 3a,b).

Bottom Line: Concomitantly, B cells lacking LRRK1 exhibited a profound defect in proliferation and survival upon BCR stimulation, which correlated with impaired BCR-mediated NF-κB activation and reduced expression of NF-κB target genes including Bcl-xL, cyclin D2, and NFATc1/αA.Furthermore, LRRK1 physically interacted and potently synergized with CARMA1 to enhance NF-κB activation.Our results reveal a critical role of LRRK1 in NF-κB signaling in B cells and the humoral immune response.

View Article: PubMed Central - PubMed

Affiliation: Department of Immunopathology, World Premier International (WPI) Immunology Frontier Research Center, Osaka University, Suita, Osaka 565-0871, Japan.

ABSTRACT
B-cell receptor (BCR) signaling plays a critical role in B-cell activation and humoral immunity. In this study, we discovered a critical function of leucine-rich repeat kinase 1 (LRRK1) in BCR-mediated immune responses. Lrrk1(-/-) mice exhibited altered B1a-cell development and basal immunoglobulin production. In addition, these mice failed to produce IgG3 antibody in response to T cell-independent type 2 antigen due to defects in IgG3 class-switch recombination. Concomitantly, B cells lacking LRRK1 exhibited a profound defect in proliferation and survival upon BCR stimulation, which correlated with impaired BCR-mediated NF-κB activation and reduced expression of NF-κB target genes including Bcl-xL, cyclin D2, and NFATc1/αA. Furthermore, LRRK1 physically interacted and potently synergized with CARMA1 to enhance NF-κB activation. Our results reveal a critical role of LRRK1 in NF-κB signaling in B cells and the humoral immune response.

No MeSH data available.


Related in: MedlinePlus