Identification, Biological Characteristics, and Active Site Residues of 3-Ketosteroid Δ1-Dehydrogenase Homologues from Arthrobacter simplex.

3-Ketosteroid Δ1-dehydrogenase (KsdD) is the key enzyme responsible for Δ1-dehydrogenation, which is one of the most valuable reactions for steroid catabolism. Arthrobacter simplex has been widely used in the industry due to its superior bioconversion efficiency, but KsdD information is not yet fully clear. Here, five KsdD homologues were identified in A. simplex CGMCC 14539. Bioinformatic analysis indicated their distinct properties and structures. Each KsdD was functionally confirmed by transcriptional response, overexpression, and heterologous expression. The substantial difference in substrate profiles might be related to the enzyme loop structure. Two promising enzymes (KsdD3 and KsdD5) were purified and characterized, exhibiting strong organic solvent tolerance and clear preference for 4-ene-3-oxosteroids. KsdD5 seemed to be more versatile due to good activity on substrates with or without a substituent at C11 and high optimal temperature and also possessed unique residues. It is the first time that KsdDs have been comprehensively disclosed in the A. simplex industrial strain.

Chloride channel involved in the regulation of curcumin-induced apoptosis of human breast cancer cells

Objective:To investigate the role of ClC-3 chloride channel in the proliferation of breast cancer cell line Mcf-7 treated with curcumin and its specific mechanism.Methods:MTT assay was used to detect the effect of chloride channel blocker (DIDS) and curcumin on Mcf-7 and human normal cell viability. Patch-clamp technique was used to determine the current density before and after drug treatment. Apoptosis assay by flow cytometry was performed for further examination of cell apoptosis.Results:Curcumin had toxicity on Mcf-7 and HUVEC cells and DIDS reduced the survival rate of Mcf-7 cells by inhibiting proliferation. Curcumin could activate the chloride ion current on MCF-7 cell membrane, which would be inhibited by DIDS. Finally, curcumin in low concentration combined with DIDS could significantly promote the MCF-7 cells apoptosis.Conclusions:Our results suggest that ClC-3 protein is involved in the regulation of curcumin induced proliferation inhibiting in breast cancer cells through inducing cell apoptosis. ClC-3 may be a potential target of tumor therapy.

Myricetin protects against lipopolysaccharide-induced disseminated intravascular coagulation by anti-inflammatory and anticoagulation effect

Objective:To explore the therapeutic effect and mechanism of myricetin on disseminated intravascular coagulation (DIC).Methods:The DIC model was established by injection of 60 mg/kg LPS in KM mice, and the treatment groups were injected myricetin with different concentrations (25 or 50 mg/kg) 30 min before the model was established. Both coagulation indicators and organ function were tested, including PT, APTT, fibrinogen, AST, ALT, BUN and tissue section. In vitro, the inflammatory model of RAW 264.7 macrophage cells were established by 10 μg/mL LPS. The treatment group was treated with 50 μmol/mL myricetin for 30 min before LPS, and the expression of TNF-α and p-NF-κB was detected, further to explore the therapeutic mechanism.Results:LPS-induced DIC led to a reduction of fibrinogen and a rise of PT, APTT, AST, ALT, BUN levels, but the treatment of myricetin significantly inhibited these abnormalities. Histopathology analysis also revealed that myricetin remarkably protected the liver and renal damage. In vitro, the expression of TNF-α and p-NF-κB induced by LPS was repressed by myricetin.Conclusions:This study provides new insights into the protective effects of myricetin in LPS-induced DIC by anticoagulant and anti-inflammatory via suppressing the activation of p-NF-κB which decreased TNF-α level.

Chloride channel involved in the regulation of curcumin-induced apoptosis of human breast cancer cells

Objective: To investigate the role of ClC-3 chloride channel in the proliferation of breast cancer cell line Mcf-7 treated with curcumin and its specific mechanism. Methods: MTT assay was used to detect the effect of chloride channel blocker (DIDS) and curcumin on Mcf-7 and human normal cell viability. Patch-clamp technique was used to determine the current density before and after drug treatment. Apoptosis assay by flow cytometry was performed for further examination of cell apoptosis. Results: Curcumin had toxicity on Mcf-7 and HUVEC cells and DIDS reduced the survival rate of Mcf-7 cells by inhibiting proliferation. Curcumin could activate the chloride ion current on MCF-7 cell membrane, which would be inhibited by DIDS. Finally, curcumin in low concentration combined with DIDS could significantly promote the MCF-7 cells apoptosis. Conclusions: Our results suggest that ClC-3 protein is involved in the regulation of curcumin induced proliferation inhibiting in breast cancer cells through inducing cell apoptosis. ClC-3 may be a potential target of tumor therapy.

Myricetin protects against lipopolysaccharide-induced disseminated intravascular coagulation by anti-inflammatory and anticoagulation effect

Objective: To explore the therapeutic effect and mechanism of myricetin on disseminated intravascular coagulation (DIC). Methods: The DIC model was established by injection of 60 mg/kg LPS in KM mice, and the treatment groups were injected myricetin with different concentrations (25 or 50 mg/kg) 30 min before the model was established. Both coagulation indicators and organ function were tested, including PT, APTT, fibrinogen, AST, ALT, BUN and tissue section. In vitro, the inflammatory model of RAW 264.7 macrophage cells were established by 10 μg/mL LPS. The treatment group was treated with 50 μmol/mL myricetin for 30 min before LPS, and the expression of TNF-α and p-NF-κB was detected, further to explore the therapeutic mechanism. Results: LPS-induced DIC led to a reduction of fibrinogen and a rise of PT, APTT, AST, ALT, BUN levels, but the treatment of myricetin significantly inhibited these abnormalities. Histopathology analysis also revealed that myricetin remarkably protected the liver and renal damage. In vitro, the expression of TNF-α and p-NF-κB induced by LPS was repressed by myricetin. Conclusions: This study provides new insights into the protective effects of myricetin in LPS-induced DIC by anticoagulant and anti-inflammatory via suppressing the activation of p-NF-κB which decreased TNF-α level.