IL1α and TNFα Induction of Monocyte Chemoattractant Protein-1 (MCP-1/JE) in Bone Marrow Stromal Cells: The Role of Protein Kinase C (PKC) and Protein Tyrosine Kinase (PTK) Activity

Abstract

Chemotactic cytokines (chemokines) have been shown to influence myelopoiesis. Bone marrow stromal cell line +/+-1. LDA11 expresses MCP-1/JE chemokine upon stimulation with ILlα and TNFα. We have examined the role of PKC and PTK dependent protein phosphorylation in induction of MCP-1/JE by using PKC and PTK specific inhibitors. PKC inhibitors staurosporine and H-7, as well as PTK inhibitors herbimycin A and genistein suppressed MCP-1/JE expression (mRNA and protein) in a dose dependent manner. The suppression of MCP-1/JE by both classes of inhibitors was partially to completely reversible. While PKC only regulated gene expression posttranscriptionally (mRNA stability), transcription of MCP-l/JE gene by ILlα and TNFα depends both upon PKC and PTK activity, as demonstrated by nuclear run-on analyses. Furthermore, treatment of cells with IL1a and TNFα involved NF-kB mobilization. There was no effect of PKC inhibitors on NF-kB mobilization by either ILlα or TNFα. In contrast, mobilization of NF-kB was negatively affected by PTK inhibitors in a stimulus selective manner (e.g., herbimycin A and genistein inhibited IL1α and TNFα induced NF-kB mobilization, respectively). We conclude from these findings that while both PKC and PTK inhibitors suppress MCP-1/JE gene transcription, only PTK inhibitors do so by suppressing NF-kB activation.