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Small-molecule inhibition and activation-loop trans-phosphorylation of the IGF1 receptor

Jinhua Wu1, Wanqing Li, Barbara P Craddock

  • 1Structural Biology Program, Kimmel Center for Biology and Medicine of the Skirball Institute of Biomolecular Medicine, Department of Pharmacology, New York University School of Medicine, New York, NY 10016, USA.

The EMBO Journal
|June 21, 2008
PubMed

Insights

We determined the crystal structure of the insulin-like growth factor-1 receptor tyrosine kinase (IGF1RK) bound to a novel inhibitor, PQIP. This structure reveals how PQIP inhibits IGF1R and insulin receptor kinases, offering insights into cancer and diabetes.

Area of Science:

  • Biochemistry
  • Structural Biology
  • Pharmacology

Background:

  • Insulin-like growth factor-1 receptor (IGF1R) is a receptor tyrosine kinase (RTK) crucial for embryonic development and tumor progression.
  • IGF1R signaling promotes cell proliferation and survival, making it a target in cancer therapy.

Purpose of the Study:

  • To elucidate the structural basis of IGF1R inhibition by a novel compound, PQIP.
  • To visualize the unphosphorylated state of the IGF1RK and its interaction with PQIP.
  • To understand the molecular mechanisms underlying IGF1R and insulin receptor (IR) kinase specificity.

Main Methods:

  • X-ray crystallography to determine the structure of IGF1RK in complex with PQIP.
  • Biochemical assays to assess the inhibitory activity of PQIP against basal and activated IGF1RK and IR.
  • Structural analysis of inhibitor-bound kinase domain and dimeric interactions.

Main Results:

  • The crystal structure of unphosphorylated IGF1RK in complex with PQIP was determined.
  • PQIP was identified as a potent inhibitor of both basal and activated IGF1RK and IR kinases.
  • The structure revealed PQIP binding to the ATP pocket and activation loop, conferring specificity for IGF1RK and IR.
  • A dimeric arrangement visualized the trans-phosphorylation event, providing a rationale for IR mutations linked to type II diabetes.

Conclusions:

  • The determined structure provides a molecular understanding of IGF1RK inhibition by PQIP.
  • PQIP's specificity for IGF1RK and IR offers potential for targeted therapies in cancer and diabetes.
  • The structural insights into RTK activation and inhibition advance our knowledge of signaling pathways and disease mechanisms.

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