Phylogenetic analysis of vertebrate CXC chemokines reveals novel lineage specific groups in teleost fish.

In this study, we have identified 421 molecules across the vertebrate spectrum and propose a unified nomenclature for CXC chemokines in fish, amphibians and reptiles based on phylogenetic analysis. Expanding on earlier studies in teleost fish, lineage specific CXC chemokines that have no apparent homologues in mammals were confirmed. Furthermore, in addition to the two subgroups of the CXCL8 homologues known in teleost fish, a third group was identified (termed CXCL8_L3), as was a further subgroup of the fish CXC genes related to CXCL11. Expression of the CXC chemokines found in rainbow trout, Oncorhynchus mykiss, was studied in response to stimulation with inflammatory and antiviral cytokines, and bacterial. Tissue distribution analysis revealed distinct expression profiles for these trout CXC chemokines. Lastly three of the trout chemokines, including two novel fish specific CXC chemokines containing three pairs of cysteines, were produced as recombinant proteins and their effect on trout leucocyte migration studied. These molecules increased the relative expression of CD4 and MCSFR in migrated cells in an in vitro chemotaxis assay.

Thrombopoietin-induced CXC chemokines, NAP-2 and PF4, suppress polyploidization and proplatelet formation during megakaryocyte maturation.

BACKGROUND: We previously reported that the expressions of two CXC chemokines, neutrophil activating peptide-2 (NAP-2) and platelet factor-4 (PF-4), were induced by megakaryocyte-specific cytokine thrombopoietin (TPO) in mouse bone marrow megakaryocytes. The roles of these chemokines on megakaryocyte maturation/differentiation processes, including polyploidization and proplatelet formation (PPF) remain unresolved. RESULTS: NAP-2 and PF-4 suppressed the PPF of mature megakaryocytes freshly prepared from mouse bone marrow as well as that of the megakaryocyte progenitors, c-Kit+CD41+ cells, isolated from mouse bone marrow and cultured with TPO. NAP-2 and PF-4 inhibited polyploidization of c-Kit+CD41+ cells in the presence of TPO, and also inhibited the proliferation of c-Kit+CD41+ cells. CONCLUSIONS: NAP-2 and PF-4 produced by TPO stimulation in megakaryocytes suppress megakaryocyte maturation and proliferation as a feedback control.

The Duffy antigen/receptor for chemokines (DARC) and prostate cancer. A role as clear as black and white?

Prostate cancer is the most commonly diagnosed cancer and the second leading cause of cancer-related death among men in the United States. African American men have a 60% greater incidence of prostate cancer and a twofold higher mortality rate than Caucasian men. The Duffy antigen/receptor for chemokines (DARC) is a receptor expressed on erythrocytes and vascular endothelial cells that binds to and clears angiogenic chemokines. The DARC also functions as the erythrocyte receptor for invasion by malarial parasites. Approximately 70% of African Americans lack erythrocyte expression of the DARC as a genetic mechanism of protection against malaria infection. Given the importance of angiogenic chemokines in the development of tumor vascular networks and the chemokine binding properties of the DARC, the possibility that a lack of DARC expression on erythrocytes may represent an epigenetic factor that predisposes African American men to a greater incidence and mortality of prostate cancer should be considered.

Isolation and characterization of mouse homolog of the neutrophil activating peptide-2.

In the presence of thrombopoietin (TPO), megakaryocytes mature by polyploidization and cytoplasmic maturation, and the matured megakaryocytes induce drastic morphological change and proplatelet formation and release a number of platelets. However, the regulatory mechanism of this unique differentiation process is still obscure. We therefore attempted to identify the factors, expression of which is induced by TPO stimulation in mouse bone marrow megakaryocytes. We isolated the mouse homolog of the neutrophil activating peptide-2 (NAP-2). Mouse NAP-2 cDNA encodes a predicted sequence of 113 amino acids and contains the Cys motif (CXC) found in other members of the alpha-chemokine family. At the amino acid level, the predicted mouse NAP-2 has 50.4%, 51.8%, and 72.6% identity with the predicted human, pig, and rat NAP-2, respectively. Northern blot analysis demonstrates that mouse NAP-2 is expressed only in spleen. Furthermore, the RT-PCR technique shows that the mouse NAP-2 gene is clearly upregulated by TPO stimulation in mouse megakaryocytes.

CXC chemokines in angiogenesis.

A variety of factors have been identified that regulate angiogenesis, including the CXC chemokine family. The CXC chemokines are a unique family of cytokines for their ability to behave in a disparate manner in the regulation of angiogenesis. CXC chemokines have four highly conserved cysteine amino acid residues, with the first two cysteine amino acid residues separated by one non-conserved amino acid residue (i.e., CXC). A second structural domain within this family determines their angiogenic potential. The NH2 terminus of the majority of the CXC chemokines contains three amino acid residues (Glu-Leu-Arg: the ELR motif), which precedes the first cysteine amino acid residue of the primary structure of these cytokines. Members that contain the ELR motif (ELR+) are potent promoters of angiogenesis. In contrast, members that are inducible by interferons and lack the ELR motif (ELR-) are potent inhibitors of angiogenesis. This difference in angiogenic activity may impact on the pathogenesis of a variety of disorders.