Control of cytokine gene expression by PG101, a water-soluble extract prepared from Lentinus lepideus

A water-soluble extract from Lentinus lepideus mycelium, named PG101, has been shown to control the expression of various cytokines [M. Jin, H.J. Jung, J.J. Choi, H.Jeon, J.H. Oh, B. Kim, S.S. Shin, J.K. Lee, K. Yoon, S. Kim, Activation of selective transcription factors and cytokines by water-soluble extract from Lentinus lepideus, Exp. Biol. Med. (Maywood) 228 (2003) 749–758]. To understand its molecular mechanism(s), PG101-mediated activation of cytokines was studied at the RNA and protein levels. Results from Northern blot analysis indicated that the steady-state RNA levels of TNF-α and seven other cytokines were highly increased in human peripheral blood mononuclear cells treated with PG101. The RNA level of TNF-α, MIP-1α, MIP-1β, MIP-3α, and IL-8 was not affected by the presence of cycloheximide, an inhibitor of the translation process, suggesting that they are the direct targets of PG101. A significantly high protein level of TNF-α, MIP-1α, and IL-8 remained detectable, even when cells were cultured with actinomycin D, 2 h prior to the PG101 treatment. Our data indicate that PG101 controls selective cellular proteins, which play key roles in the innate immune system, at the transcriptional and post-translational levels.