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Induction of cytosolic calcium flux by CD20 Is dependent upon B cell antigen receptor signaling

Induction of cytosolic calcium flux by CD20 Is dependent upon B cell antigen receptor signaling
Induction of cytosolic calcium flux by CD20 Is dependent upon B cell antigen receptor signaling
The anti-CD20 monoclonal antibody (mAb) rituximab is now routinely used for the treatment of non-Hodgkins lymphoma and is being examined in a wide range of other B-cell disorders, such as rheumatoid arthritis. Despite intensive study, the mechanism of action still remains uncertain. In the current study, anti-CD20 mAb-induced calcium signaling was investigated. Previously, we grouped anti-CD20 mAbs into Type I (rituximab-like) and Type II (B1-like) based upon various characteristics such as their ability to induce complement activation and redistribute CD20 into detergent-insoluble membrane domains. Here we show that only Type I mAbs are capable of inducing a calcium flux in B cells and that this is tightly correlated with the expression of the B-cell antigen receptor (BCR). Inhibitor analysis revealed that the signaling cascade employed by CD20 was strikingly similar to that utilized by the BCR, with inhibitors of Syk, Src, and PI3K, but not EGTA, p38, or ERK1/2, completely ablating calcium flux. Furthermore, binding of Type I but not Type II mAbs caused direct association of CD20 with the BCR as measured by FRET and resulted in the phosphorylation of BCR-specific adaptor proteins BLNK and SLP-76. Crucially, variant Ramos cells lacking BCR expression but with unchanged CD20 expression were completely unable to induce calcium flux following ligation of CD20. Collectively, these data indicate that CD20 induces cytosolic calcium flux through its ability to associate with and “hijack” the signaling potential of the BCR
0021-9258
16971-16984
Walshe, Claire A.
dc2839de-0958-478e-a3fe-e7ed361fcda2
Beers, S.A.
a02548be-3ffd-41ab-9db8-d6e8c3b499a2
French, Ruth R.
a95ea7a1-7aeb-4c20-998e-fde663613fd1
Chan, H.T. Claude
b109c93f-7e9a-44ee-ad12-da757b1b11fc
Johnson, P. W.
3f6068ce-171e-4c2c-aca9-dc9b6a37413f
Packham, Graham
fdabe56f-2c58-469c-aadf-38878f233394
Glennie, Martin J.
9f6f0eff-4560-48c2-80cd-0ec116110ded
Cragg, Mark S.
ec97f80e-f3c8-49b7-a960-20dff648b78c
Walshe, Claire A.
dc2839de-0958-478e-a3fe-e7ed361fcda2
Beers, S.A.
a02548be-3ffd-41ab-9db8-d6e8c3b499a2
French, Ruth R.
a95ea7a1-7aeb-4c20-998e-fde663613fd1
Chan, H.T. Claude
b109c93f-7e9a-44ee-ad12-da757b1b11fc
Johnson, P. W.
3f6068ce-171e-4c2c-aca9-dc9b6a37413f
Packham, Graham
fdabe56f-2c58-469c-aadf-38878f233394
Glennie, Martin J.
9f6f0eff-4560-48c2-80cd-0ec116110ded
Cragg, Mark S.
ec97f80e-f3c8-49b7-a960-20dff648b78c

Walshe, Claire A., Beers, S.A., French, Ruth R., Chan, H.T. Claude, Johnson, P. W., Packham, Graham, Glennie, Martin J. and Cragg, Mark S. (2008) Induction of cytosolic calcium flux by CD20 Is dependent upon B cell antigen receptor signaling. The Journal of Biological Chemistry, 283 (25), 16971-16984. (doi:10.1074/jbc.M708459200).

Record type: Article

Abstract

The anti-CD20 monoclonal antibody (mAb) rituximab is now routinely used for the treatment of non-Hodgkins lymphoma and is being examined in a wide range of other B-cell disorders, such as rheumatoid arthritis. Despite intensive study, the mechanism of action still remains uncertain. In the current study, anti-CD20 mAb-induced calcium signaling was investigated. Previously, we grouped anti-CD20 mAbs into Type I (rituximab-like) and Type II (B1-like) based upon various characteristics such as their ability to induce complement activation and redistribute CD20 into detergent-insoluble membrane domains. Here we show that only Type I mAbs are capable of inducing a calcium flux in B cells and that this is tightly correlated with the expression of the B-cell antigen receptor (BCR). Inhibitor analysis revealed that the signaling cascade employed by CD20 was strikingly similar to that utilized by the BCR, with inhibitors of Syk, Src, and PI3K, but not EGTA, p38, or ERK1/2, completely ablating calcium flux. Furthermore, binding of Type I but not Type II mAbs caused direct association of CD20 with the BCR as measured by FRET and resulted in the phosphorylation of BCR-specific adaptor proteins BLNK and SLP-76. Crucially, variant Ramos cells lacking BCR expression but with unchanged CD20 expression were completely unable to induce calcium flux following ligation of CD20. Collectively, these data indicate that CD20 induces cytosolic calcium flux through its ability to associate with and “hijack” the signaling potential of the BCR

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Published date: 21 April 2008

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Local EPrints ID: 148355
URI: http://eprints.soton.ac.uk/id/eprint/148355
ISSN: 0021-9258
PURE UUID: 802470e6-f20f-48d3-bc0d-cc34539b25b2
ORCID for S.A. Beers: ORCID iD orcid.org/0000-0002-3765-3342
ORCID for H.T. Claude Chan: ORCID iD orcid.org/0000-0003-0530-9480
ORCID for P. W. Johnson: ORCID iD orcid.org/0000-0003-2306-4974
ORCID for Graham Packham: ORCID iD orcid.org/0000-0002-9232-5691
ORCID for Mark S. Cragg: ORCID iD orcid.org/0000-0003-2077-089X

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Date deposited: 28 Apr 2010 08:16
Last modified: 14 Mar 2024 02:45

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Contributors

Author: Claire A. Walshe
Author: S.A. Beers ORCID iD
Author: Ruth R. French
Author: H.T. Claude Chan ORCID iD
Author: P. W. Johnson ORCID iD
Author: Graham Packham ORCID iD
Author: Mark S. Cragg ORCID iD

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