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-alpha and seven other cytokines were highly increased in human peripheral blood mononuclear cells treated with PG101. The RNA level of TNF-alpha, MIP-1alpha, MIP-1beta, MIP-3alpha, 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-alpha, MIP-1alpha, and IL-8 remained detectable, even when cells were cultured with actinomycin D, 2h 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.