P48 is a cytokine which induces monocyte differentia-tion and the induction of cytotoxic activity. In this study,the signal transduction events involved in the stimulation of monocytes with the membrane form of P48 (m...P48 is a cytokine which induces monocyte differentia-tion and the induction of cytotoxic activity. In this study,the signal transduction events involved in the stimulation of monocytes with the membrane form of P48 (mP48) were investigated. Monocyte stimulation with mP48 was found to involve the mobilization of intracellular calcium (Ca2+)and the activation and translocation of PKC from the cy-tosol to the membrane. Membane P48 induced a rapid rise of intracellular Ca2+ in a dose dependent maner. Simi-larly the stimulation of monocytes with P48 was found to involve the activation and translocation of PKC. The translocation of PKC was rapid (within 0-5 min) yet tran-sient with PKC activity returning to control levels by 8 min. The functional role of protein kineses in P48 induced TNF secretion was studied using various kinese inhibitors. The PKC inhibitors, H-7 and sphingosine, were found to inhibit P48 induced TNF secretion with 50% inhibition at 5μM HA1004, which inhibts cyclic nucleotide-dependent kinase (PKA, Ki 1.2μM), did not inhibit TNF secretion. H-8 (PKA inhibitor) was found to be an effective inhibitor of TNF secretion only at high concentrations(30μp. The Calmodulin-dependent kinase inhibitor, W7 (Ki 12μM)was found to be effective at concentration above 5μM.These findings suggest that P48-triggered TNF secretion involves transmembrane Ca2+ signaling and the subse-quent activation of at least two protein kineses, PKC and CaMK.展开更多
文摘P48 is a cytokine which induces monocyte differentia-tion and the induction of cytotoxic activity. In this study,the signal transduction events involved in the stimulation of monocytes with the membrane form of P48 (mP48) were investigated. Monocyte stimulation with mP48 was found to involve the mobilization of intracellular calcium (Ca2+)and the activation and translocation of PKC from the cy-tosol to the membrane. Membane P48 induced a rapid rise of intracellular Ca2+ in a dose dependent maner. Simi-larly the stimulation of monocytes with P48 was found to involve the activation and translocation of PKC. The translocation of PKC was rapid (within 0-5 min) yet tran-sient with PKC activity returning to control levels by 8 min. The functional role of protein kineses in P48 induced TNF secretion was studied using various kinese inhibitors. The PKC inhibitors, H-7 and sphingosine, were found to inhibit P48 induced TNF secretion with 50% inhibition at 5μM HA1004, which inhibts cyclic nucleotide-dependent kinase (PKA, Ki 1.2μM), did not inhibit TNF secretion. H-8 (PKA inhibitor) was found to be an effective inhibitor of TNF secretion only at high concentrations(30μp. The Calmodulin-dependent kinase inhibitor, W7 (Ki 12μM)was found to be effective at concentration above 5μM.These findings suggest that P48-triggered TNF secretion involves transmembrane Ca2+ signaling and the subse-quent activation of at least two protein kineses, PKC and CaMK.
