Effect of Interleukin-10 on Lipopolysaccahride/Interferon-gamma- Induced Chemokine Mig Gene Expression

Interferon-gamma (IFN-gamma) is well known as a potent inducer in monokine induced by IFN-gamma (Mig) mRNA expression. Although lipopolysaccharide (LPS) alone is weakly effective on Mig mRNA expression. the stimulation of LPS and IFN-gamma (LPS/IFN-gamma simultaneously has been shown to synergize to produce a high level of Mig mRNA in mouse peritoneal macrophages. In this study, interleukin-10 (IL-10) was found to suppress the LPS/IFN-gamma- induced Mig mRNA expression in cell type- and mouse strain-specific fashion, but IFN-gamma alone-induced Mig mRNA was unaffected by IL-10 under identical experimental conditions. The IL-10-mediated suppression of LPS/IFN-gamma-stimulated Mig mRNA expression was dependent on the concentration of IL-10, and was prevented when the agent was added 2 hours after LPS/IFN-gamma treatment. The suppressive action of IL-10 was dependent on a protein synthesis. However, IL-10 did not reduce the stability of LPS/IFN-gamma-induced Mig mRNA. These data may have important implications for a previously unrecognized role for IL-10 as a regulator of synergistic effect of LPS on the IFN-gamma-induced expression of the Mig gene in macrophages.

IS6110 - RFLP Analysis using Mycobacterium tuberculosis Isolates from Taegu - Kyungpook Region

No abstract available.

Overexpression, purification and truncation analysis of RmlC protein of Mycobacterium tuberculosis

dTDP-rhamnose provides L-rhamnose to the bridge-like structure between mycolyl arabinogalactan and peptidoglycan of the mycobacterial cell wall. dTDP-rhamnose is composed of glucose-1-phosphate and dTTP by four enzymes encoded by rmlA-D. To determine the region(s) of RmlC protein essential for its dTDP-4-keto-6-deoxyglucose epimerase activity, we overexpressed both whole (202 amino acids) and three different truncated (N-terminal 106 or 150 or C-terminal 97 amino acids) RmlC proteins of Mycobacterium tuberculosis. The RmlC enzyme activity in the soluble lysates of DELTArmlC E. coli strain SPHI874 (DE3 PlysS) expressing the wild type or truncated rmlC genes was initially analyzed by three sequential reactions from dTDP-glucose to dTDP-rhamnose in the presence of purified RmlB and RmlD. All three soluble lysates containing the truncated RmlC proteins showed no enzyme activity, while that containing the wild type RmlC was active. This wild type RmlC was then overexpressed and purified. The incubation of the purified RmlC enzyme so obtained with dTDP-4-keto-6-deoxyglucose resulted in the conversion of dTDP-4-keto-rhamnose. The results show that the truncated regions of the RmlC protein are important for the RmlC enzyme activity in M. tuberculosis.