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Cited by 52T-cell and B-cell ImmunologyImmunodeficiency and Autoimmune DisordersNF-κB Signaling Pathways

Activation of Lyn, Blk, and Btk But Not Syk in CD72-Stimulated B Lymphocytes

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Venkataraman, Chandrasekar, Muthusamy, Natarajan, Muthukkumar, Subramanian, Bondada, Subbarao·1998·The Journal of Immunology
DOI 10.4049/jimmunol.160.7.3322
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Abstract

CD72 is a B cell-specific glycoprotein that has been shown to be important for activation of mature B cells. Previously we showed that some of the early signaling events, such as calcium mobilization and phospholipase-γ activation, were similar in B cell Ag receptor (BCR)- and CD72-stimulated B cells and that BCR- but not CD72-mediated early signaling events were blocked by protein kinase A activation. The present report shows that CD72 ligation induces a variety of tyrosine-phosphorylated proteins, most of which were of the same molecular mass as those seen in anti-IgM-treated B cells, except for a 72-kDa protein. Further analysis showed that the tyrosine kinases lyn and blk were activated in CD72-ligated B cells. Interestingly, the non-src kinase syk was not activated in CD72-stimulated cells whereas the tec family kinase btk was activated in both CD72- and BCR-stimulated B cells. Furthermore, B cells from xid mice were unresponsive to CD72-induced proliferation, indicating an essential role for btk in CD72-induced signaling events. Surprisingly, tyrosine phosphorylation of phospholipase C-γ2 was normal in CD72-stimulated cells in spite of a lack of activation of syk. Furthermore, B cell proliferation through CD72 was blocked by the immunosuppressive agents cyclosporin A and FK506, indicating the important role for Ca2+-regulated activation events similar to BCR-stimulated cells. We propose that btk can substitute for syk in inducing phospholipase C-γ2 tyrosine phosphorylation and initiating calcium mobilization in CD72-stimulated B lymphocytes.

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  • PLCγ2 is required for signaling of CD72, a regulatory molecule important in B cell development, although this process is thought to rely on Btk instead of Syk.

    “In addition to this crucial role in BCR signaling, PLCγ2 is also required for the signaling of CD72, a regulatory molecule important in B cell development, although it is thought this process relies on Btk instead of Syk (23).”

    From The role of PLCγ2 in immunological disorders, cancer, and neurodegeneration (2021) · cites this paper as [23]

    The section on PLCγ2 phosphorylation reports that CD72 stimulation phosphorylates PLCγ2 while Btk, but not Syk, is activated. The Discussion proposes that Btk may substitute for Syk in this pathway. The paper does not establish that PLCγ2 is required for CD72 signaling; it shows phosphorylation, not a test of necessity. (LLM, conf=0.86)

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Authors
Venkataraman, C., Muthusamy, N., Muthukkumar, S., & Bondada, S.
Affiliations
University of Kentucky (US)
ORCID
Venue
The Journal of Immunology
Publisher
Oxford University Press (OUP)
Published
1998-04-01
Volume
160
Issue
7
Pages
3322-3329
ISSN
  • 0022-1767 (ISSN-L)
  • 1550-6606
DOI
10.4049/jimmunol.160.7.3322
OpenAlex
W1516604621
Cited by
52
References
52
Citations by year
2026: 1 · 2021: 1 · 2015: 1 · 2013: 1 · 2012: 1
FWCI
2.52
Type
journal article
Language
en
Open access
Licence
academic.oup.com/pages/standard-publication-reuse-rights (vor)
Locations
  • The Journal of Immunology (publishedVersion)
  • PubMed (publishedVersion)
Funders
National Institute of Allergy and Infectious Diseases (AI 21490, AI05731, R01AI021490)
Topics
  • Life Sciences › Immunology and Microbiology › Immunology › T-cell and B-cell Immunology
  • Life Sciences › Immunology and Microbiology › Immunology › Immunodeficiency and Autoimmune Disorders
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cancer Research › NF-κB Signaling Pathways
Keywords
CD72, B cell activation, Lyn kinase, Syk, Tec family kinases, PLCγ2, tyrosine phosphorylation, calcium mobilization, protein kinase A, xid mice, cyclosporine, FK506, B cell proliferation, B cell receptor signaling
MeSH terms
Syk Kinase, Agammaglobulinaemia Tyrosine Kinase, Animals, Antigens, Differentiation, B-Lymphocyte, Enzyme Precursors, Female, Immune Tolerance, Immunologic Deficiency Syndromes, Lymphocyte Activation, Mice, Inbred BALB C, Mice, Inbred CBA, Mice, Inbred DBA, Mice, Mutant Strains, Type C Phospholipases, Phosphorylation, Protein-Tyrosine Kinases, Substrate Specificity, Tyrosine, X Chromosome, Antigens, CD, B-Lymphocyte Subsets, Tacrolimus, Cyclosporine, src-Family Kinases, Intracellular Signaling Peptides and Proteins, Mice

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