Discovery of a CXCR4 agonist pepducin that mobilizes bone marrow hematopoietic cells

Proc Natl Acad Sci U S A. 2010 Dec 21;107(51):22255-9. doi: 10.1073/pnas.1009633108. Epub 2010 Dec 7.

Abstract

The G protein-coupled receptor (GPCR), chemokine CXC-type receptor 4 (CXCR4), and its ligand, CXCL12, mediate the retention of polymorphonuclear neutrophils (PMNs) and hematopoietic stem and progenitor cells (HSPCs) in the bone marrow. Agents that disrupt CXCL12-mediated chemoattraction of CXCR4-expressing cells mobilize PMNs and HSPCs into the peripheral circulation and are therapeutically useful for HSPC collection before autologous bone marrow transplantation (ABMT). Our aim was to develop unique CXCR4-targeted therapeutics using lipopeptide GPCR modulators called pepducins. A pepducin is a synthetic molecule composed of a peptide derived from the amino acid sequence of one of the intracellular (IC) loops of a target GPCR coupled to a lipid tether. We prepared and screened a small CXCR4-targeted pepducin library and identified several pepducins with in vitro agonist activity, including ATI-2341, whose peptide sequence derives from the first IC loop. ATI-2341 induced CXCR4- and G protein-dependent signaling, receptor internalization, and chemotaxis in CXCR4-expressing cells. It also induced dose-dependent peritoneal recruitment of PMNs when administered i.p. to mice. However, when administered systemically by i.v. bolus, ATI-2341 acted as a functional antagonist and dose-dependently mediated release of PMNs from the bone marrow of both mice and cynomolgus monkeys. ATI-2341-mediated release of granulocyte/macrophage progenitor cells from the bone marrow was confirmed by colony-forming assays. We conclude that ATI-2341 is a potent and efficacious mobilizer of bone marrow PMNs and HSPCs and could represent a previously undescribed therapeutic approach for the recruitment of HSPCs before ABMT.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chemotaxis / drug effects
  • Dose-Response Relationship, Drug
  • HEK293 Cells
  • Hematopoietic Stem Cell Mobilization*
  • Hematopoietic Stem Cells / metabolism*
  • Humans
  • Leukocytes, Mononuclear / metabolism
  • Macaca fascicularis
  • Mice
  • Mice, Inbred BALB C
  • Peptides / pharmacology*
  • Receptors, CXCR4 / agonists*
  • Receptors, CXCR4 / metabolism
  • Signal Transduction / drug effects*

Substances

  • CXCR4 protein, human
  • CXCR4 protein, mouse
  • Peptides
  • Receptors, CXCR4