Other Chemokines

Mouse Lungkine/CXCL15 (WECHE) belongs to the ELR motif-containing CXC chemokines. The mouse Lungkine gene has been mapped to chromosome 5. The cDNA of mouse Lungkine encodes a 166 amino acids (aa) protein with a 25 aa predicted signal peptide and a 141 aa mature protein with an exceptionally long C-terminal tail which extends beyond beyond the chemokine fold. Lungkine protein is secreted into bronchoalveolar space and is involved in lung-specific neutrophils trafficking. Furthermore, studies in Lungkine knockout mice propose that Lungkine is an imperative mediator of neutrophil migration from the lung parenchyma into the airspace. In addition, Lungkine is chemotactic for bone marrow progenitor cells and modulates hematopoietic cell differentiation. By Northern blot analysis and in-situ hybridization, Lungkine transcripts have only been specifically detected in the adult and fetal lung, and its expression is up-regulated under inflammatory conditions. There is a 35% aa sequence similarity between the mouse Lungkine and the human ENA-78 and a 31% similarity with the human IL-8.

Human CCL16, also called HCC-4, liver-expressed chemokine (LEC), and lymphocyte and monocyte chemoattractant (LMC), is a novel CC chemokine recognized by bioinformatics. NCC-4 cDNA encodes a 120 amino acids along with a 23 amino acids signal peptide that is cleaved to generate 97 amino acid protein. HCC4 is vaguely related to other CC chemokines, showing less than 30% sequence identity. Among CC chemokines, CCL-16 has the largest similarity to HCC-1. 2 potential polyadenylation signals are present on the human HCC-4 gene, and as a result, 2 transcripts containing roughly 1,500 base pairs and 500 base pairs have been detected. HCC-4 is expressed weakly by some lymphocytes, including NK cells, T cells, and some T cell clones. The expression of HCC-4 in monocytes is greatly upregulated in the presence of IL-10.
CCL16 shows chemotactic activity for lymphocytes and monocytes rather than to neutrophils. NCC-4 has potent myelosuppressive activity, suppresses proliferation of myeloid progenitor cells. CCL16 demonstrates chemotactic activity for monocytes and thp-1 monocytes, rather than for resting lymphocytes and neutrophils. HCC-4 induces a calcium flux in thp-1 cells that desensitized prior to the expression of rantes.

Family With Sequence Similarity 19 Member-A5 (FAM19A5) belongs to the TAFA family which is comprised of 5 highly homologous genes encoding small secreted proteins. These proteins have conserved cysteine residues at fixed positions, and are remotely related to MIP-1alpha, which is a member of the CC-chemokine family. The TAFA proteins are primarily expressed in specific regions of the brain, and are assumed to serve as brain-specific chemokines or neurokines which act as regulators of immune and nervous cells.