ATI-2341, pepducin targeting the C-X-C chemokine receptor type 4 (CXCR4), is an allosteric agonist activating the inhibitory heterotrimeric G protein (Gi) to promote inhibition of cAMP production and induce calcium mobilization.

ATI-2341 induces CXCR4- and G protein-dependent signaling, receptor internalization, and chemotaxis in CXCR4-expressing cells. It is the most potent agonist with an EC50 value of 194 ± 16 nM and an intrinsic activity of 81 ± 4%. ATI-2341 is a potent and efficacious mobilizer of bone marrow PMNs(polymorphonuclear neutrophils) and HSPCs(hematopoietic stem and progenitor cells) and could represent a previously undescribed therapeutic approach for the recruitment of HSPCs before ABMT(autologous bone marrow transplantation). ATI-2341 is able to induce chemotaxis of CCRF-CEM cells, inducing the typical bell-shaped curve observed with chemotactic agents[1].

Intraperitoneal (i.p.) injection of ATI-2341 in BALB/c mice results in a dose-dependent recruitment of PMNs into the peritoneum, with a maximal effect seen at 405 nmol/kg. A higher concentration of ATI-2341 results in reduced recruitment, which is reminiscent of the bell-shaped curve generally seen with chemotactic agents. Intravenous (i.v.) administration of ATI-2341 in mice results in a dose-dependent increase in PMNs in the peripheral circulation, measured 90 min after administration of compound. The effect is maximal at 0.66 μMol/kg of ATI-2341. ATI-2341 has no effect on the mobilization of lymphocytes at any dose tested[1].

Receptors(CXCR4-eGFP) are transiently transfected into HEK-293 cells and are plated 24 h after transfection on glass coverslips coated with poly-D-lysine. The next day, cells are treated with either vehicle alone or with varying concentrations of ATI-2341 for 30 min at 37 °C followed by fixation with methanol for 5 min at −20 °C. GFP fluorescence is visualized directly using a Zeiss Axiovert inverted microscope. Images are processed using Adobe Photoshop and Adobe Illustrator. (Only for Reference)