Potential role for Duffy antigen chemokine-binding protein in angiogenesis and maintenance of homeostasis in response to stress.

CXC chemokines, which induce angiogenesis, have glutamine-leucine-arginine amino acid residues (ELR motif) in the amino terminus and bind CXCR2 and the Duffy antigen chemokine-binding protein. Duffy, a seven transmembrane protein that binds CXC and CC chemokines, has not been shown to couple to trimeric G proteins or to transduce intracellular signals, although it is highly expressed on red blood cells, endothelial cells undergoing neovascularization, and neuronal cells. The binding of chemokines by Duffy could modulate chemokine responses positively or negatively. Positive regulation could come through the presentation of chemokine to functional receptors, and negative regulation could come through Duffy competition with functional chemokine receptors for chemokine binding, thus serving as a decoy receptor. To determine whether Duffy has a role in angiogenesis and/or maintenance of homeostasis, we developed transgenic mice expressing mDuffy under the control of the preproendothelin promoter/enhancer (PPEP), which directs expression of the transgene to the endothelium. Two PPEP-mDuffy-transgenic founders were identified, and expression of the transgene in the endothelium was verified by Northern blot, RT-PCR, and immunostaining of tissues. The phenotype of the mice carrying the transgene appeared normal by all visual parameters. However, careful comparison of transgenic and nontransgenic mice revealed two phenotypic differences: mDuffy-transgenic mice exhibited a diminished angiogenic response to MIP-2 in the corneal micropocket assay, and mDuffy-transgenic mice exhibited enhanced hepatocellular toxicity and necrosis as compared with nontransgenic littermates in response to overdose of acetaminophen (APAP; 400 mg/kg body weight). Morover, APAP treatment was lethal in 50% of the mDuffy-transgenic mice 24 h post challenge, and 100% of the nontransgenic littermates survived this treatment at the 24 h time point. Our data suggest that enhanced expression of mDuffy on endothelial cells can lead to impaired angiogenic response to chemokines and impaired maintenance of homeostasis in response to toxic stresses.