Effects Of PI3K On The Expression Of ERK And TNF-α In Fractalkine-induced Peripheral Blood Mononuclear Cells

FKN has been shown to play an important role in inflammatory vascular diseases, such as atherosclerosis. but the underlying mechanism has not been elucidated. FKN is so far the only member of theδ-chemokine subclass. It could stimulate the directional migration of leukocytes and mediate inflammation. FKN displays features that distinguishes it from the other chemokines.It include a CX3C motif, a mucin-like stalk tethering the chemokine domain to transmembrane spanning, and short intracellular domains. Fractalkine thus exists in 2 forms, as a membrane- anchored protein (m-FKN) or as a soluble chemotactic peptide (s-FKN), the effects of which remain poorly documented.CX3CR1 is a high-affinity receptor for fractalkine, corresponding to a classical heptahelical chemokine receptor. This receptor was shown to mediate both the adhesive and migration functions of fractalkine. Chemokine receptors identified to date on leukocytes all present a 7-transmembrane G protein-linke dstructure. They have been shown to transduce signals that lead to cytoskeletal reorganization, integrin activation, and other functions required to increase adhesion and migration of the cells.To date, information on the cellular signaling triggered by chemokine is scarce. In this study, we verifed the effects of PI3K on the expression of ERK and TNF-αin fractalkine-induced peripheral blood mononuclear cells to investigated the molecular mechanism by which FKN participate inflammati- on.Materials and methods PBMC were isolated from fresh blood of healthy volunteers by Ficoll-Paque gradient centrifugation.The extractive PBMC were divided into four groups with different treatment :control group,FKN group, FKN+PD98059 group and FKN+LY294002 group.Each group was divided into two shares. We measured phosphorylated ERK1/2 in one share using wes- tern blot analysis after 45min of incubation with FKN, Each blot was representative of 3 independent experiments; Collected culture liquid of the other share and evaluated TNF-αexpression by enzyme-linked immuno sorbent assay(ELISA) after 24h of incubation with FKN.Resultsp-ERK1/2 and TNF-αlevel of FKN group enhanced compared with control group(P<0.05). p-ERK1/2 and TNF-αlevel of FKN+PD98059 group decreased compared with FKN group(P<0.05).p-ERK1/2 and TNF-αlevel of FKN+LY294002 group reduced compared with FKN group(P<0.05).ConclusionOur results demonstrated that FKN participated inflammation in atheroge- nesis by activating the MEK/ERK/TNF-αsignal pathways; These biochemical events were partly inhibited by the PI3K inhibitor LY294002;PI3K was the up stream signal of ERK activation promoted by FKN;PI3K mediated the expres- sion of TNF-αstimulated by FKN,which probably achieved through the ERK pathway.