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TULA: an SH3- and UBA-containing protein that binds to c-Cbl and ubiquitin

Elena A Feshchenko1, Evgeniya V Smirnova, Gayathri Swaminathan

  • 1Department of Microbiology and Immunology, Temple University School of Medicine, Philadelphia, PA 19140, USA.

Oncogene
|April 27, 2004
PubMed

Insights

T-cell Ubiquitin LigAnd (TULA) protein regulates c-Cbl, a key protein tyrosine kinase downregulator. TULA counters c-Cbl

Area of Science:

  • Cellular biology
  • Molecular biology
  • Biochemistry

Background:

  • c-Cbl is a multidomain protein crucial for downregulating protein tyrosine kinases.
  • The regulation of c-Cbl's function is not well understood.
  • Protein tyrosine kinases are vital in cellular signaling and transformation.

Purpose of the Study:

  • To identify novel regulators of c-Cbl.
  • To investigate the functional role of TULA in c-Cbl-mediated signaling.
  • To elucidate the mechanism by which TULA affects c-Cbl activity.

Main Methods:

  • Affinity chromatography to purify c-Cbl-associated proteins.
  • Mass spectrometry for protein identification.
  • Co-expression studies in 293T cells and Jurkat T-lymphoblastoid cells to assess protein function.
  • Western blotting and reporter assays to measure protein activity and degradation.

Main Results:

  • T-cell Ubiquitin LigAnd (TULA) was identified as a c-Cbl-associated protein.
  • TULA inhibits c-Cbl-mediated downregulation of the Epidermal Growth Factor (EGF) receptor.
  • TULA upregulates Zap kinase and NF-AT transcription factor activity.
  • TULA induces ubiquitylation and degradation of c-Cbl, thereby inhibiting its effects.

Conclusions:

  • TULA acts as a negative regulator of c-Cbl, countering its inhibitory effects on protein tyrosine kinases.
  • TULA plays a significant role in modulating cellular signaling pathways regulated by c-Cbl.
  • TULA's mechanism involves promoting c-Cbl degradation, suggesting a novel regulatory pathway in tyrosine kinase signaling.

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