👤 Masayuki Iwano

Mycoplasma bovis is a pathogenic bacterium in bovines that causes huge global economic losses. Numerous factors play important roles in M. bovis pathogenesis; however, the host immune response involved in M. bovis infection has not been fully elucidated. We aimed to determine the characteristics of the host immune response to Mycoplasma infection. We evaluated the responsiveness of bovine peripheral blood mononuclear cells (PBMCs) stimulated with M. bovis via microarray analysis. The transcriptional abundance of innate immune-related genes IL-36A, IL-27, IFN-γ, and IL-17 in PBMCs increased after M. bovis exposure. Upon M. bovis infection, there was increased expression of the lymphocyte activated genes basic leucine zipper transcription factor (BATF) and signaling lymphocytic activation molecule family members 1 and 7 (SLAMF 1 and SLAMF 7) in PBMCs compared with that in unstimulated cells. The study revealed that the transcriptional abundance of innate immunity genes in PBMCs increased during M. bovis infection. This induced the activation of PBMCs, giving rise to an immune response, which is followed by the development of the inflammatory response. The results from this study could be used as the basis for the development of novel vaccine candidates against M. bovis. Show less

Statins decrease cholesteryl ester transfer protein (CETP) levels, which have been positively associated with hepatic lipid content as well as serum low density lipoproteins-cholesterol (LDL-C) levels. However, the relationship between the CETP status and statin-induced reductions in LDL-C levels has not yet been elucidated in detail. We herein examined the influence of the CETP status on the lipid-reducing effects of pitavastatin in hypercholesterolemic patients with type 2 diabetes mellitus as well as the molecular mechanism underlying pitavastatin-induced modifications in CETP levels. Fifty-three patients were treated with 2 mg of pitavastatin for 3 months. Serum levels of LDL-C, small dense (sd) LDL-C, and CETP were measured before and after the pitavastatin treatment. The effects of pitavastatin, T0901317, a specific agonist for liver X receptor (LXR) that reflects hepatic cholesterol contents, and LXR silencing on CETP mRNA expression in HepG2 cells were also examined by a real-time PCR assay. The pitavastatin treatment decreased LDL-C, sdLDL-C, and CETP levels by 39, 42, and 23%, respectively. Despite the absence of a significant association between CETP and LDL-C levels at baseline, baseline CETP levels and its percentage change were an independent positive determinant for the changes observed in LDL-C and sdLDL-C levels. The LXR activation with T0901317 (0.5 μM), an in vitro condition analogous to hepatic cholesterol accumulation, increased CETP mRNA levels in HepG2 cells by approximately 220%, while LXR silencing markedly diminished the increased expression of CETP. Pitavastatin (5 μM) decreased basal CETP mRNA levels by 21%, and this was completely reversed by T0901317. Baseline CETP levels may predict the lipid-reducing effects of pitavastatin. Pitavastatin-induced CETP reductions may be partially attributed to decreased LXR activity, predictable by the ensuing decline in hepatic cholesterol synthesis. UMIN Clinical Trials Registry ID UMIN000019020. Show less

Cytochrome P450 (CYP) 1A1 is involved in the metabolic activation of polycyclic aromatic hydrocarbons (PAHs) and is induced by several compounds, including PAHs. The induction of CYP1A1 mediated by the aryl hydrocarbon receptor (AhR) has been well investigated; however, little has been reported on the mechanisms of CYP1A1 induction mediated by factors other than AhR. In this study, we investigated the involvement of liver X receptor alpha (LXRα) in the induction of CYP1A1. TO-901317, an LXRα ligand, induced CYP1A1 mRNA in a dose-dependent fashion. Luciferase reporter assays using HepG2 cells showed that TO-901317 was capable of activating the promoter of the CYP1A1 gene and that a direct repeat 4 (DR4) motif located in a region from -452 to -467 was required for the induction of CYP1A1 through LXRα. Specific binding of LXRα to this DR4 motif was confirmed by gel shift and chromatin immunoprecipitation assays. Co-treatment of HepG2 cells with TO-901317 and 2,3,7,8-tetrachlorodibenzo-p-dioxin, a typical AhR ligand, caused the synergistic induction of CYP1A1 mRNA. Thus, we propose that the expression of CYP1A1 is regulated by LXRα as well as by AhR, suggesting that exposure to both LXRα and AhR ligands can result in the alteration of individual susceptibility to environmental carcinogens metabolically activated by CYP1A1. Show less

Industrial yeasts, including a sake yeast Kyokai no. 7 (K7), are generally unable to sporulate. In K7 (Saccharomyces cerevisiae) cells, IME1 transcription was not induced under sporulation conditions, and K7 cells partially restored sporulation ability when transformed with a multicopy plasmid bearing IME1. However, the mechanisms of sporulation incompetence in industrial yeasts are poorly understood. We demonstrated that the deletion of the G1 cyclin CLN3, a key activator of the cell cycle, allows K7 cells to induce IME1 transcription and sporulate under sporulation conditions. In K7 cells, CLN3 mRNA and protein were not down-regulated despite sporulation conditions. Moreover, using a two-hybrid assay, we found that Ime1-Ume6 interaction was promoted in Cln3-deficient K7 cells. Thus, Cln3 is involved in the mechanism underlying sporulation incompetence by inhibiting IME1 transcription and the Ime1-Ume6 interaction. Based on these findings, we hypothesize that the absence of transmission of nutrient starvation signals to CLN3 leads to sporulation incompetence in K7 cells. Show less