Lysine-specific demethylase 1 represses THP-1 monocyte-to-macrophage differentiation / 中国医学科学杂志(英文版)

<p><b>OBJECTIVE</b>To investigate the role of lysine-specific demethylase 1 (LSD1) in the process of THP-1 monocyte-to-macrophage differentiation.</p><p><b>METHODS</b>Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blotting were performed to analyze the expression of LSD1 and interleukin-6 (IL-6) in THP-1 monocytes and THP-1-derived macrophages. Chromatin immunoprecipitation (ChIP) assay was applied to detect the occupancy of LSD1 and H3K4 methylation at IL-6 promoter during THP-1 monocyte-to-macrophage differentiation. IL-6 mRNA level and H3K4 methylation at IL-6 promoter were analyzed using qRT-PCR and ChIP assay in LSD1-knockdown THP-1 cells treated with 12-O-tetradecanoylphorbol-13-acetate (TPA) for 0, 4, 8, 12, and 24 hours. Fluorescence activated flow cytometry was performed to reveal the percentage of macrophages differentiated from THP-1 monocytes.</p><p><b>RESULTS</b>The expression of LSD1 reduced during THP-1 monocyte-to-macrophage differentiation (P<0.01). LSD1 occupancy decreased and H3K4 methylation increased at IL-6 promoter during the differentiation. With knockdown of LSD1, H3K4 methylation at IL-6 promoter was found increased after TPA treatment at different times points (all P<0.05, except 24 hours). The percentage of macrophages increased significantly in the THP-1 cells with LSD1 knockdown (P<0.05).</p><p><b>CONCLUSIONS</b>LSD1 is repressed during the monocyte-to-macrophage differentiation of THP-1 cells. Suppression of LSD1-mediated H3K4 demethylation may be required for THP-1 monocyte-to-macrophage differentiation.</p>

Lipoxygenase-mediated N-demethylation of pesticides in vitro / 中华劳动卫生职业病杂志

<p><b>OBJECTIVE</b>In order to explore the pathway of dealkylation of pesticides other than cytochrome P450 monocoxygenases, lipoxygenase (LOX)-mediated demethylation of aminocarb and some other pesticides were measured.</p><p><b>METHOD</b>Formaldehyde generated in the reaction was estimated by Nash reaction to express the rate of demethylation of pesticides mediated by soy lipoxygenase (SLO).</p><p><b>RESULTS</b>N-demethylation of aminocarb mediated by SLO was found to depend on the incubation time, concentration of the enzyme, concentration of aminocarb and hydrogen peroxide. Under optimal conditions, Vmax value of 18 nmol of formaldehyde.min-1.nmol-1 of lipoxygenase was observed. The reaction exhibited Km values of 3.4 mmol/L for aminocarb and 235 mumol/L for hydrogen peroxide. A strong inhibition of the reaction by nordihydroguaiaretic acid, gossypol, and phenidone clearly implicated the lipoxygenase involvement as the protein catalyst. A significant decline in the formaldehyde accumulation in the presence of either reduced glutathione or dithiothreitol suggested generation of a free radical species as an initial oxidation intermediate during the demethylation of aminocarb by SLO. The inhibition of formaldehyde generation by butylated hydroxyanisole(BHT) and butylated hydroxy toluene(BHA) further supported this contention. In addition to aminocarb, seven other pesticides were also found to undergo N-demethylation, albeit at relatively low rates.</p><p><b>CONCLUSION</b>Certain pesticides may oxidatively undergo dealkylation via the lipoxygenase pathway in animals and plants.</p>