Magnolol induces the distributional changes of p160 and adipose differentiation-related protein in adrenal cells
Journal
Histochemistry and Cell Biology
Journal Volume
123
Journal Issue
4-5
Pages
429-439
Date Issued
2005
Author(s)
Abstract
Magnolol stimulates adrenal steroidogenesis and induces the distributional changes of p160 and adipose differentiation-related protein (ADRP) in rat adrenal cells. This study investigated the underlying signaling mechanisms involved in these processes. Magnolol (30 μM) caused a time-dependent increase in the phosphorylation of extracellular signal-related kinase (ERK) in cultured adrenal cells. The following evidence supports a link between ERK activation and p160 translocation. First, the magnolol-induced redistribution of p160 from the lipid droplet surface to the cytosol, resulting in the decrease in the percentages of p160-positive cells, and this decrease in p160-positive cells was completely blocked by pretreatment with either of the MAPK-ERK kinase (MEK) inhibitors PD98059 or U0126. Second, magnolol did not significantly decrease total p160 protein levels but caused an increase in threonine phosphorylation of p160, which reached a maximum after 5 min of magnolol treatment, and this magnolol-induced phosphorylation of p160 was prevented by pretreatment with U0126, suggesting the involvement of ERK. In addition, magnolol decreased both ADRP immunostaining intensity at the lipid droplet surface and the percentage of ADRP-positive cells. This was further confirmed biochemically by the decrease in ADRP levels in total cell homogenates and in lipid droplet fractions. Magnolol-induced decrease in ADRP staining at the lipid droplet surface was not affected by pretreatment with PD98059 or U0126, indicating that ERK signaling was not involved in this event. Furthermore, treatment with 30 μM magnolol for 6 h resulted in about 50% decrease in ADRP protein level. Therefore, decreased protein levels of p160 and ADRP at the lipid droplet surface induced by magnolol were mediated via two different mechanisms: phosphorylation of p160 and downregulation of ADRP expression, respectively. ? Springer-Verlag 2005.
SDGs
Other Subjects
1,4 diamino 1,4 bis(2 aminophenylthio) 2,3 dicyanobutadiene; 2 (2 amino 3 methoxyphenyl)chromone; adipophilin; fat droplet; magnolol; mitogen activated protein kinase; mitogen activated protein kinase inhibitor; protein p160; threonine; adrenal cell; animal cell; article; cell differentiation; cell free system; controlled study; down regulation; enzyme activation; female; immunohistochemistry; lipid analysis; nonhuman; obesity; priority journal; protein blood level; protein phosphorylation; rat; signal transduction; surface property; Adrenal Glands; Animals; Biphenyl Compounds; Blotting, Western; Butadienes; Cells, Cultured; Cytoplasmic Granules; Enzyme Inhibitors; Extracellular Signal-Regulated MAP Kinases; Female; Flavonoids; Fluorescent Antibody Technique; Histone Acetyltransferases; Lignans; Lipid Metabolism; Membrane Proteins; Microscopy, Fluorescence; Nitriles; Oxazoles; Phosphoprotein Phosphatase; Phosphorylation; Protein Transport; Pyrans; Rats; Rats, Wistar; Spiro Compounds; Time Factors; Transcription Factors
Type
journal article