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Small-molecule inhibition of APT1 affects Ras localization and signaling

Frank J Dekker1, Oliver Rocks, Nachiket Vartak

  • 1Department of Chemical Biology, Max Planck Institute for Molecular Physiology, Dortmund, Germany.

Nature Chemical Biology
|April 27, 2010
PubMed

Insights

Palmitoylation cycles control protein localization. A new inhibitor, palmostatin B, targets acyl protein thioesterase 1 (APT1), disrupting depalmitoylation and reversing cancer cell phenotypes.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Molecular Pharmacology

Background:

  • Palmitoylation and depalmitoylation are dynamic post-translational modifications regulating peripheral membrane protein localization and function.
  • Aberrant signaling from palmitoylated Ras proteins contributes to oncogenesis.
  • Targeting the acylation cycle offers a strategy to modulate Ras-driven signaling pathways.

Purpose of the Study:

  • To develop and characterize a potent inhibitor of acyl protein thioesterase 1 (APT1), a key depalmitoylating enzyme.
  • To investigate the effects of APT1 inhibition on the cellular acylation cycle and protein localization.
  • To evaluate the therapeutic potential of APT1 inhibition in oncogenic Ras-transformed cells.

Main Methods:

  • Knowledge-based design and synthesis of small molecule inhibitors.
  • Biochemical assays to characterize enzyme inhibition kinetics.
  • Cellular assays to assess protein localization, acylation status, and phenotypic changes.
  • Identification of cellular targets using biochemical and genetic approaches.

Main Results:

  • Palmostatin B was identified as a potent inhibitor of APT1.
  • Palmostatin B disrupts the depalmitoylation step in the cellular acylation cycle.
  • Inhibition of APT1 by palmostatin B leads to delocalization of palmitoylated Ras proteins.
  • Palmostatin B treatment induced partial phenotypic reversion in HRasG12V-transformed fibroblasts.
  • APT1 was confirmed as a cellular target of palmostatin B.

Conclusions:

  • APT1 is a critical depalmitoylating enzyme involved in regulating the localization of palmitoylated proteins like Ras.
  • Palmostatin B is a valuable chemical probe for studying the acylation cycle and APT1 function.
  • Inhibiting APT1 represents a potential therapeutic strategy for cancers driven by oncogenic Ras.

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