CCL28 Daniel J. Catron1 and Albert Zlotnik2,* 1 Department of Molecular Pathology, DNAX Research Institute of Molecular and Cellular Biology Inc., 901 California Avenue, Palo Alto, CA 94304-1104, USA 2 Eos Biotechnology Inc., 225A Gateway Boulevard, South San Francisco, CA 94080, USA * corresponding author tel: (650) 246-2313, fax: (650) 583-3881, e-mail: email@example.com DOI: 10.1006/rwcy.2001.1127. Chapter posted 5 November 2001 SUMMARY CCL28 is a member of the CC family of chemokines. It is found on human chromosome 5 and on murine chromosome 13. Both human and mouse CCL28 have six cysteines, four of which are conserved by other CC chemokines. CCL28 displays chemotactic activity for resting CD4 and CD8 T cells. CCL27 and CCL28 share the chemokine receptor CCR10, formerly known as GPR2. BACKGROUND Discovery An EST for CCL28 was identified by performing a homology-based search (TBLASTN) against the GenBank2 dbEST database using a human chemokine consensus query sequence (Wang et al., 2000). The clone containing the EST was obtained through the IMAGE Consortium (clone 136910) and sequenced to confirm the presence of a full-length open reading frame. Mouse CCL28 was cloned from a kidney cDNA library from Rag-1 knockout mice using the full-length human CCL28 as a probe. Human and mouse CCL28 are highly conserved, being 83% identical at the amino acid level and 76% identical at the nucleotide level. Alternative names CCL28 is the systematic ligand nomenclature as described by Zlotnik and Yoshie (2000) while Cytokine Reference SCYA28 is the systematic gene nomenclature. Another report called this chemokine MEC, for mucosa-associated chemokine (Pan et al., 2000). Structure No structural studies have been reported on CCL28. Main activities and pathophysiological roles Recombinant human CCL28 attracts resting CD4 and CD8 T cells. The marked expression of CCR10 and CCL28 in the gastrointestinal tract suggests possible roles in the homeostasis and inflammatory responses of the gastrointestinal system (Wang et al., 2000). GENE AND GENE REGULATION Accession numbers Mouse CCL28: AF220238 Human CCL28: AF220210 Chromosome location Mouse CCL28 maps to a distal region of chromosome 13 according to interspecific backcross analysis. This region is syntenic with human chromosome 5q. Copyright # 2001 Academic Press 2 Daniel J. Catron and Albert Zlotnik As such, human CCL28 is the first chemokine to map to chromosome 5. Discussion of crystal structure No structural studies have been reported. Cells and tissues that express the gene Northern blotting indicates human CCL28 is predominantly expressed in prostate, colon, spleen, and to a lesser degree by peripheral blood leukocytes. Mouse CCL28 is predominantly expressed in testes and less so in the kidney and brain. Using real time quantitative PCR (TaqMan2 ), human CCL28 is shown to be expressed in lymphoid and hematopoietic libraries. Human and mouse CCL28 is most highly expressed by normal and pathological cells of the colon. TaqMan assays also showed mouse CCL28 to be highly expressed in mesenteric lymph nodes, Peyer's patches, and stomach cells. Immunohistochemical staining suggests that epithelial cells produce CCL28. Important homologies The CC chemokines with the greatest degree of homology to CCL28 are CCL27/CTACK, CCL25/ TECK, CCL17/TARC, CCL20/MIP-3, and CCL19/MIP-3. Posttranslational modifications While CCL28 is glycosylated in its native form, it is unknown if this affects the activity of the protein. CELLULAR SOURCES AND TISSUE EXPRESSION PROTEIN Accession numbers Cellular sources that produce include epithelial cells and some leukocyte subsets. Mouse CCL28: AAF87206 Human CCL28: AAF87205 RECEPTOR UTILIZATION Sequence See Figure 1. Description of protein Both human and mouse CCL28 contain six cysteines. There are two cysteine residues in addition to the four conserved ones normally found in CC chemokines. It is hypothesized that the additional disulfide bond might confine the extended C-terminal tail to the body of the chemokine. The CCL28 receptor has been identified as the former orphan receptor GPR2, now called CCR10. Realtime, quantitative PCR (TaqMan2 ) was used to determine expression levels in various cDNA libraries derived from various human organs and cell types. CCR10 is expressed in dermal microvascular endothelial cells, dermal fibroblasts, melanocytes, T cells, and skin-derived Langerhans cells. In organs, CCR10 is most highly expressed in the small intestine and colon and to a lesser degree in fetal liver, fetal lung, fetal spleen, fetal testes, fetal brain, and uterus, among others (Homey et al., 2000; Jarmin et al., Figure 1 Mouse and human CCL28 amino acid sequences. Mouse CCL28: MQQAGLTLMA VAVCVAFQTS EAILPMASSC CTEVSHHVSG RLLERVSSCS IQ RADGDCDL AAVILHVKRR RICISPHNRT LKQWMRASEV KKNGRENVCS GKK QPSRKDR KGHTTRKHRT RGTHRHEASR Human CCL28: MQQRGLAIVA LAVCAALHAS EAILPIASSC CTEVSHHISR RLLERVNMCR IQR ADGDCDL AAVILHVKRR RICVSPHNHT VKQWMKVQAA KKNGKGNVCH RK KHHGKRNS NRAHQGKHET YGHKTPY CCL28 2000). CCR10 is also the receptor for CCL27. Calcium flux experiments show CCL28 is able to specifically desensitize human and mouse CCR10transfectants to CCL27 (and vice versa) (Wang et al., 2000). CCR10 is expressed in some T cell and B cell lines, but not in normal B cells. This suggests that normal B cells may respond to CCL28 under certain circumstances, but not in the resting state. general by epithelial cells elsewhere including salivary gland, trachea, and mammary epithelium. IN THERAPY Preclinical ± How does it affect disease models in animals? IN VITRO ACTIVITIES No studies have been reported. In vitro findings Effects of therapy: Cytokine, antibody to cytokine inhibitors, etc. Recombinant human CCL28 attracts resting CD4 and CD8 T cells. Bioassays used Transwell chemotaxis assay. IN VIVO BIOLOGICAL ACTIVITIES OF LIGANDS IN ANIMAL MODELS Normal physiological roles Possibly chemoattracts resting CD4 and CD8 T cells and certain activated B cells. Species differences Because the human and mouse forms of CCL28 share a high degree of homology and have comparable expression patterns, similar biological activities are expected. PATHOPHYSIOLOGICAL ROLES IN NORMAL HUMANS AND DISEASE STATES AND DIAGNOSTIC UTILITY Normal levels and effects Human and mouse CCL28 is highly expressed in normal and pathological tissues of the colon and in 3 No studies have been reported. References Homey, B., Wang, W., Soto, H., Buchanan, M. E., Wiesenborn, A., Catron, D., Muller, A., McClanahan, T. K., Dieu-Nosjean, M. C., Orozco, R., Ruzicka, T., Lehmann, P., Oldham, E., and Zlotnik, A. (2000). Cutting edge: the orphan chemokine receptor G protein-coupled receptor-2 (GPR-2, CCR10) binds the skin-associated chemokine CCL27 (CCL27/ALP/ILC). J. Immunol. 164, 3465±3470. Jarmin, D. I., Rits, M., Bota, D., Gerard, N. P., Graham, G. J., Clark-Lewis, I., and Gerard, C. (2000). Cutting edge: identification of the orphan receptor G-protein-coupled receptor 2 as CCR10, a specific receptor for the chemokine ESkine. J. Immunol. 164, 3460±3464. Pan, J., Kunkel, E. J., Gosslar, U., Lazarus, N. I., Langdon, P., Broadwell, K., Vierra, M. A., Genovese, M. C., Butcher, E. C., and Soler, D. (2000). A novel chemokine ligand for CCR10 and CCR3 expressed by epithelial cells in mucosal tissues. J. Immunol. 165, 2943±2949. Wang, W., Soto, H., Oldham, E. R., Buchanan, M. E., Homey, B., Catron, D., Jenkins, N., Copeland, N. G., Gilbert, D. J., Nguyen, N., Abrams, J., Kershenovich, D., Smith, K., McClanahan, T., Vicari, A. P., and Zlotnik, A. (2000). Identification of a novel chemokine (CCL28), which binds to CCR10 (GPR2). J. Biol. Chem. 275, 22313±22323. Zlotnik, A., and Yoshie, O. (2000). Chemokines: a new classification system and their role in immunity. Immunity 12, 121±127.