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Negative regulation of CD45 by differential homodimerization of the alternatively spliced isoforms

Zheng Xu1, Arthur Weiss

  • 1Department of Medicine and the Howard Hughes Medical Institute, University of California, San Francisco, CA 94143-0795, USA.

Nature Immunology
|July 23, 2002
PubMed

Insights

CD45 protein tyrosine phosphatase (PTP) dimerization in T cells is modulated by glycosylation of its alternatively spliced exons. This regulation impacts T cell receptor signaling and may control T cell response termination.

Area of Science:

  • Immunology
  • Molecular Biology
  • Cell Signaling

Background:

  • Receptor-like protein tyrosine phosphatases (RPTPs) play crucial roles in cell signaling, but their regulation is not fully understood.
  • CD45, a key RPTP in T cells, is known to be negatively regulated by dimerization, but the mechanisms controlling this process remain unclear.

Purpose of the Study:

  • To investigate how CD45 dimerization is modulated in T cells.
  • To explore the role of alternative splicing, sialylation, and O-glycosylation in CD45 homodimerization.
  • To understand the functional consequences of CD45 isoform-specific dimerization on T cell receptor signaling.

Main Methods:

  • Analysis of differential homodimerization of various CD45 isoforms in T cells.
  • Investigation of the impact of sialylation and O-glycosylation on CD45 dimerization.
  • Assessment of the relationship between CD45 isoform dimerization and T cell receptor signaling.

Main Results:

  • Different CD45 isoforms exhibit differential homodimerization in T cells.
  • Sialylation and O-glycosylation of alternatively spliced CD45 exons in the extracellular domain modulate dimerization.
  • The smallest isoform, CD45RO, with minimal extracellular glycosylation, shows the highest homodimerization efficiency.
  • Increased CD45 homodimerization leads to decreased T cell receptor signaling.

Conclusions:

  • Alternative splicing of CD45, coupled with differential glycosylation, provides a mechanism for regulating RPTP function in T cells.
  • The findings suggest a novel mechanism for the termination of primary T cell responses by modulating CD45 activity.
  • This study highlights the biological significance of alternative splicing in immune system regulation.

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