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Regulation of multiple functions of SHPS-1, a transmembrane glycoprotein, by its cytoplasmic region

Ryuji Sato1, Hiroshi Ohnishi, Hisae Kobayashi

  • 1Biosignal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-Machi, Maebashi, Gunma 371-8512, Japan.

Biochemical and Biophysical Research Communications
|September 10, 2003
PubMed

Insights

The cytoplasmic region of SHPS-1 regulates its binding affinity to CD47 and affects cell shape. Mutations in this region enhance CD47 binding and alter cytoskeletal organization.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • SHPS-1 (Src homology 2 domain-containing phosphatase-substrate 1) is a transmembrane glycoprotein involved in cell-cell communication.
  • Its cytoplasmic region contains tyrosine residues crucial for SHP-2 binding, while the extracellular region interacts with CD47.
  • Understanding the SHPS-1/CD47 interaction is key to deciphering cellular signaling pathways.

Purpose of the Study:

  • To investigate the role of the SHPS-1 cytoplasmic region in regulating the interaction with CD47.
  • To analyze how mutations in the SHPS-1 cytoplasmic region affect binding affinity, oligomerization, and cytoskeletal organization.
  • To elucidate the contribution of SHPS-1 to cell shape and migration dynamics.

Main Methods:

  • Utilized Chinese hamster ovary (CHO) cells expressing wild-type (WT) and mutant SHPS-1 (deltaCyto and 4F).
  • Analyzed ligand-receptor interactions using recombinant CD47-Fc.
  • Employed chemical cross-linking to study SHPS-1 dimerization.
  • Assessed cell morphology, actin stress fiber formation, lamellipodium formation, and membrane ruffling.

Main Results:

  • Mutant SHPS-1 (deltaCyto and 4F) exhibited greater binding affinity and oligomerization with CD47-Fc compared to WT SHPS-1.
  • SHPS-1 forms cis-dimers, as indicated by chemical cross-linking.
  • WT SHPS-1 expressing cells showed less polarization and reduced actin stress fibers compared to mutant cells.
  • Enhanced lamellipodium formation and membrane ruffling were observed at the leading edges of migrating WT cells.

Conclusions:

  • The cytoplasmic region of SHPS-1 is critical for modulating its binding affinity to CD47.
  • SHPS-1 clustering ability and its impact on cytoskeletal reorganization are regulated by its cytoplasmic domain.
  • These findings highlight the importance of the SHPS-1 cytoplasmic region in cell-cell communication and cellular dynamics.

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