Proteomic Evaluation of Cellular Responses of Saccharomyces cerevisiae to Formic Acid Stress

Formic acid is a representative carboxylic acid that inhibits bacterial cell growth, and thus it is generally considered to constitute an obstacle to the reuse of renewable biomass. In this study, Saccharomyces cerevisiae was used to elucidate changes in protein levels in response to formic acid. Fifty-seven differentially expressed proteins in response to formic acid toxicity in S. cerevisiae were identified by 1D-PAGE and nano-liquid chromatography-tandem mass spectrometry (nano-LC-MS/MS) analyses. Among the 28 proteins increased in expression, four were involved in the MAP kinase signal transduction pathway and one in the oxidative stress-induced pathway. A dramatic increase was observed in the number of ion transporters related to maintenance of acid-base balance. Regarding the 29 proteins decreased in expression, they were found to participate in transcription during cell division. Heat shock protein 70, glutathione reductase, and cytochrome c oxidase were measured by LC-MS/MS analysis. Taken together, the inhibitory action of formic acid on S. cerevisiae cells might disrupt the acid-base balance across the cell membrane and generate oxidative stress, leading to repressed cell division and death. S. cerevisiae also induced expression of ion transporters, which may be required to maintain the acid-base balance when yeast cells are exposed to high concentrations of formic acid in growth medium.

Effect of TAL and MAPK signal transduction on alveolar macrophage apoptosis and activity of chronic bronchitis rats / 中国药理学通报

Aim To investigate the effect of TAL and MAPK signal transduction on alveolar macrophage (AM) apoptosis and activity of chronic bronchitis (CB) rats.Methods CB model was established by BCG+LPS method and the in vitro and in vivo experiments were used. MTT method was used to detect the AM activity,and the apoptosis of AM was observed by electron microscope.Results The number of AM in BALF of CB rats was increased than that of normal group (P<0.01).The activity of AM was increased in model group than in control group.The apoptotic rate of AM in CB group was much lower than that in the control group [(13.93±3.34)% vs (5.37±1.38)%] (P<0.01).ERK inhibitor PD98059 induced the apoptosis of cultured AM while JNK inhibitor Curcumin reduced the apoptosis.TAL could inhibit ERK MAPK phosphorylation in AM of CB rats.Further investigation showed that Bcl-2 protein expression was significantly increased while Bax evidently decreased in AM of CB rats.TAL could significantly decrease Bcl-2 expression and increase Bax protein expression, which might be the mechanism of its effect.Conclusions There is an increased activity and decreased apoptosis of AM in CB rats compared with normal rats. TAL can inhibit AM activity and increase apoptosis of AM in CB rats which may be related to the therapeutic effect of CB. ERK and JNK MAPK signal transduction participates in the apoptosis of AM. Regulation of Bcl-2/Bax imbalance and MAPK phosphorylation in AM of CB rats might be the mechanism of its effect.