CCL27

CCL27 Daniel J. Catron1,* and Albert Zlotnik2 1Department

of Molecular Biology, DNAX Research Institute of Molecular and Cellular Biology Inc., 901 California Avenue, Palo Alto, CA 94304-1104, USA

2Eos

Biotechnology, 225A Gateway Blvd, South San Francisco, CA 94080, USA

* corresponding author tel: (650) 496-1242, fax: (650) 496-1200, e-mail: [email protected] DOI: 10.1006/rwcy.2001.11026.

SUMMARY CTACK/CCL27 is a member of the or CC family of chemokines. It is found on human chromosome 9p13 and on murine chromosome 4. CCL27 is distinct from other chemokines in several ways: (1) its gene is located on the opposite reading frame overlapping the gene encoding the  chain of the interleukin 11 receptor (Baird et al., 1999; Ishikawa-Mochizuki et al., 1999) and (2) it is specifically expressed in skin by keratinocytes (Morales et al., 1999), although alternatively spliced forms are also expressed in testis, heart, and liver (Hromas et al., 1999). CCL27 chemoattracts CLA+ memory T cells. The CCL27 receptor is CCR10 (formerly known as GPR2) (Homey et al., 2000; Jarmin et al., 2000).

genome, which contains a 104 amino acid open reading frame (called MC148R) with homology to the CC family of chemokines. With this sequence, a homology-based search (BLAST) against a public EST database was performed. Two mouse ESTs were identified as potentially containing a novel chemokine. Clones were obtained, sequenced, and used to construct a full-length ORF. The mouse cDNA was used to probe for the genomic clone. It was speculated that the IL-11R chain might be located in syntenic chromosomal regions. The human genomic sequence containing the IL-11R gene was identified and a gene-prediction algorithm was used to search for adjacent genes. CCL27 exons 2 and 3 were identified and human CCL27 was successfully cloned from a human thymus cDNA library.

BACKGROUND

Alternative names

Discovery

CCL27 (systematic ligand nomenclature; Zlotnik and Yoshie, 2000); SCYA27 (systematic gene nomenclature); ESkine (named for embroyonal stem cell system chemokine); ILC (named for IL-11R-locus chemokine); ALP (named for peptide sequence located at the signal peptide cleavage site).

CCL27 was identified as a novel EST derived from a human skin cDNA library and mouse CCL27 was identified from a whole mouse embryo cDNA library (Morales et al., 1999). Mouse CCL27 was also reported by Baird et al., (1999) from a library created through subtractive hybridization of nascently differentiated placental murine embryonal stem (ES) cells and was called ESkine. Mouse CCL27 shares a 149 base pair overlap with a portion of the IL-11 receptor  chain gene. While the two genes share 30 regions, their frames run in reverse orientations. CCL27 also shares 82% homology at the nucleotide level with the extreme 30 untranslated region of the IL-11R chain (Baird et al., 1999). Concurrently, Ishikawa-Mochizuki et al., (1999) studied the molluscum contagiosum virus (MCV-1)

Cytokine Reference

Structure No structural studies have yet been reported on CCL27.

Main activities and pathophysiological roles CCL27 preferentially attracts skin-homing CLA+ memory T cells to cutaneous sites (Morales et al.,

Copyright # 2001 Academic Press

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Daniel J. Catron and Albert Zlotnik

1999). CCL27 is likely to be involved in skin homeostasis and host defense (Homey et al., 2000).

Figure 1 Amino acid sequences for mouse and human CCL27.

GENE AND GENE REGULATION

Accession numbers Mouse CCL27: AF082392 Human CCL27: NM006664

Chromosome location CCL27 is located on murine chromosome 4 and human chromosome 9p13. The 30 end of CCL27 and IL-11 receptor  share a sizable overlap. The two genes are in reverse reading frames with respect to one another.

Cells and tissues that express the gene CCL27 is expressed in the placenta (Baird et al., 1999). However, CCL27 is predominantly expressed by keratinocytes (Homey et al., 2000). CCL27 is skinspecific and is secreted via the endocytic pathway in mammalian cells. It has a non-secreted splice variant, PESKY, which is expressed in the testes and brain. Rather than a signal peptide, PESKY has a charged domain and is expressed in the nucleus (Baird et al., 1999).

PROTEIN

Accession numbers Mouse CCL27: AAD41237 Human CCL27: NP006655

Sequence

There are insertions of three or four residues not seen in any other CC chemokines.

Discussion of crystal structure No crystal structure is known yet.

Important homologies CCL27 has 37% identity to CCL20 (formerly known as MIP-3/LARC/CK 4/Exodus-1/SCYA 20) and 35% identity to CCL25 (formerly known as TECK/ CK 15).

Posttranslational modifications While CCL27 is glycosylated in its native form, it is unknown if glycosylation affects the activity of the protein.

CELLULAR SOURCES AND TISSUE EXPRESSION

Cellular sources that produce CCL27 is predominantly expressed in the placenta; PESKY in the testes and brain (Baird et al., 1999). It is constitutively expressed by keratinocytes (Homey et al., 2000).

See Figure 1.

Description of protein No structural features are known yet. CCL27 contains an extended C-terminus necessary for functional activity. It is missing the conserved phenylalanine, alanine, and valine seen in all other CC chemokines.

Eliciting and inhibitory stimuli, including exogenous and endogenous modulators Expression is upregulated upon stimulation with TNF and IL-1 . Subsequent treatment with IL-10

CCL27 can downregulate CCL27 expression (Homey et al., 2000).

RECEPTOR UTILIZATION The CCL27 receptor has been identified as the former orphan receptor GPR2, now called CCR10. Realtime, quantitative TaqMan PCR 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., 2000). The differential expression of CCL27 and CCR10 in cell types sequestered from one another suggest several possibilities. Perhaps CCL27 may be temporally expressed in other locations through an inflammatory-mediated upregulation. Alternatively, there might be an as yet undiscovered intermediate ligand for CCR10 that is expressed in the common tissues (Homey et al., 2000). It has been suggested that CCL27/CCR10 plays a role in wound repair (Homey et al., 2000). As keratinocytes do not express CCR10, these cells might be responsible for the migration and/or differentiation of other cellular components of the skin under either normal or inflammatory conditions. CCL27 is strongly expressed by keratinocytes in both normal and inflammatory conditions (Homey et al., 2000).

IN VIVO BIOLOGICAL ACTIVITIES OF LIGANDS IN ANIMAL MODELS

Normal physiological roles Possibly chemoattracts CLA+ memory T cells in vivo.

Species differences The human and mouse forms of CCL27 share a high degree of homology.

PATHOPHYSIOLOGICAL ROLES IN NORMAL HUMANS AND DISEASE STATES AND DIAGNOSTIC UTILITY

Normal levels and effects Keratinocytes express CCL27 at consistent levels in both normal and inflamed human skin (Homey et al., 2000).

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.

CCL27 chemoattracts CLA+ memory T cells (Morales et al., 1999). Cutaneous lymphocyteassociated antigen (CLA) is a cell surface-expressed ligand for the vascular adhesion receptor E-selectin. The interaction of CLA+ memory T cells and Eselectin in the presence of a CCL27 gradient enable this subset of T cells to specifically home in on cutaneous inflammatory sites. There is a bell-shaped dose response to SEBactivated PBMCs (Baird et al., 1999).

Bioassays used Transwell chemotaxis assay.

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No studies have been reported.

References Baird, J. W., Nibbs, R. J., Komai-Koma, M., Connolly, J. A., Ottersbach, K., Clark-Lewis, I., Liew, F. Y., and Graham, G. J. (1999). ESkine, a novel beta-chemokine, is differentially spliced to produce secretable and nuclear targeted isoforms. J. Biol. Chem. 274, 33496±33503. Homey, B., Wang, W., Soto, H., Buchanan, M. E., Wiesenborn, A., Catron, D., Muller, A., McClanahan, T. K., DieuNosjean, M. C., Orozco, R., Ruzicka, T., Lehmann, P., Oldham, E., and Zlotnik, A. (2000). Cutting edge: the orphan

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chemokine receptor G protein-coupled receptor-2 (GPR-2, CCR10) binds the skin-associated chemokine CCL27 (CCL27/ ALP/ILC). J. Immunol. 164, 3465±3470. Hromas, R., Broxmeyer, H. E., Kim, C., Christopherson, K. II, and Hou, Y. H. (1999). Isolation of ALP, a novel divergent murine CC chemokine with a unique carboxy terminal extension. Biochem. Biophys. Res. Commun. 258, 737±740. Ishikawa-Mochizuki, I., Kitaura, M., Baba, M., Nakayama, T., Izawa, D., Imai, T., Yamada, H., Hieshima, K., Suzuki, R., Nomiyama, H., and Yoshie, O. (1999). Molecular cloning of a novel CC chemokine, interleukin-11 receptor alpha-locus chemokine (ILC), which is located on chromosome 9p13 and a potential homologue of a CC chemokine encoded by molluscum contagiosum virus. FEBS Lett. 460, 544±548.

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, 346. Morales, J., Homey, B., Vicari, A. P., Hudak, S., Oldham, E., Hedrick, J., Orozco, R., Copeland, N. G., Jenkins, N. A., McEvoy, L. M., and Zlotnik, A. (1999). CCL27, a skin-associated chemokine that preferentially attracts skin-homing memory T cells. Proc. Natl Acad. Sci. USA 96, 14470±14475. Zlotnik, A., and Yoshie, O. (2000). Chemokines: a new classification system and their role in immunity. Immunity 12, 121±127.