The mammalian homologue of the novel peptide Bv8 is expressed in the central nervous system and supports neuronal survival by activating the MAP kinase/PI-3-kinase pathways.

Previous studies have identified the mammalian homologue of Bv8 (mBv8), a small protein originally isolated from skin secretions of the frog, Bombina variegata. In situ hybridization showed that mBv8 RNA was widely expressed in the rodent CNS, with high levels being detected in layer II of the cerebral cortex, limbic regions, cerebellar Purkinje cells, and dorsal and ventral horns of the spinal cord. A similar pattern of distribution was found by examining the presence of mBv8 protein by immunocytochemistry. Addition of frog Bv8 to cultured cerebellar granule cells reduced the extent of apoptotic death induced by switching the growing medium from 25 to 5 mM K+. Bv8 could also protect cultured cortical neurons against excitotoxic death. Both effects were prevented by PD98059 and LY294002, which inhibit the mitogen-activated protein kinase (MAPK) and phosphatidylinositol-3-kinase (PI-3-K) pathways, respectively. In cultured cerebellar granule cells, Bv8 stimulated both the MAPK and the PI-3-K pathways, as revealed by Western blot analysis of phosphorylated p44/p42 MAPKs and phosphorylated Akt, respectively. We conclude that mBv8 acts as an endogenous neurotrophic factor and supports neuronal survival through the activation of the MAPK/PI-3-K pathways.

Neuroprotective activity of chemokines against N-methyl-D-aspartate or beta-amyloid-induced toxicity in culture.

We have examined the effect of various chemokines on neuronal toxicity in culture. In mixed cortical cultures, challenged with a brief pulse of N-methyl-D-aspartate (NMDA, 60 microM, 10 min), chemokines were either present for 2 h preceding the pulse or they were co-applied with NMDA and then kept in the medium for the following 20-24 h. Interleukin-8 (IL-8), regulated on activation of normal T cells expressed and secreted (RANTES) and macrophage/monocyte chemoattractant protein-1 (MCP-1), were neuroprotective under both conditions, whereas stromal cell-derived factor 1alpha (SDF-1alpha) was protective only when applied during and after the NMDA pulse. Mixed or pure neuronal cultures were also exposed for 48 h to a toxic fragment of the beta-amyloid peptide (beta-amyloid peptide-(25-35), 12.5 or 25 microM) in the absence or presence of chemokines. Among a number of chemokines, only RANTES was neuroprotective against beta-amyloid peptide-(25-35)-induced neurotoxicity in both cultures. We conclude that activation of chemokine receptors differentially affects neuronal degeneration induced by excitotoxins or beta-amyloid peptide in cortical cultures.