The synthetic chemoattractant peptide, Trp-Lys-Tyr-Met-Val-D-Met, enhances monocyte survival via PKC-dependent Akt activation.

Previously, we showed that Trp-Lys-Tyr-Met-Val-D-Met (WKYMVm) stimulates superoxide generation and chemotactic migration in monocytes and neutrophils. In this study, we examined the effect of WKYMVm on monocyte survival. Serum starvation-induced monocyte death was attenuated in the presence of WKYMVm, which was abated when the cells were preincubated with LY294002, suggesting the involvement of phosphoinositide-3-kinase (PI 3-kinase) in the peptide-induced monocyte survival. WKYMVm stimulated ERK and Akt activity via PI 3-kinase activation in monocytes. We also investigated the signaling pathway of WKYMVm-induced ERK and Akt activation. The WKYMVm-induced ERK activation was PI 3-kinase-dependent but PKC-independent. However, Akt activation by WKYMVm was dependent not only on PI 3-kinase but also on the PKC pathway. When monocytes were incubated with WKYMVm, caspase-3 activity, which is important for cell death, was inhibited. Pretreatment of the cells with LY294002, GF109203X, and Go 6976 but not PD98059 blocked WKYMVm-induced monocyte survival and caspase-3 inhibition. In summary, the novel chemoattractant WKYMVm enhances monocyte survival via Akt-mediated pathways, and in this process, PKC and PI 3-kinase act upstream of Akt.