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Ursolic acid, a natural pentacyclic triterpenoid, inhibits intracellular trafficking of proteins and induces accumulation of intercellular adhesion molecule-1 linked to high-mannose-type glycans in the endoplasmic reticulum.

Mitsuda S, Yokomichi T, Yokoigawa J, Kataoka T - FEBS Open Bio (2014)

Bottom Line: By contrast, ursolic acid exerted weak inhibitory effects on the IL-1α-induced ICAM-1 expression at the protein level.Surprisingly, we found that ursolic acid decreased the apparent molecular weight of ICAM-1 and altered the structures of N-linked oligosaccharides bound to ICAM-1.Thus, our results reveal that ursolic acid inhibits intracellular trafficking of proteins and induces the accumulation of ICAM-1 linked to high-mannose-type glycans in the endoplasmic reticulum.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan.

ABSTRACT
Ursolic acid (3β-hydroxy-urs-12-en-28-oic acid) is a natural pentacyclic triterpenoid that is present in many plants, including medicinal herbs, and foods. Ursolic acid was initially identified as an inhibitor of the expression of intercellular adhesion molecule-1 (ICAM-1) in response to interleukin-1α (IL-1α). We report here a novel biological activity: ursolic acid inhibits intracellular trafficking of proteins. Ursolic acid markedly inhibited the IL-1α-induced cell-surface ICAM-1 expression in human cancer cell lines and human umbilical vein endothelial cells. By contrast, ursolic acid exerted weak inhibitory effects on the IL-1α-induced ICAM-1 expression at the protein level. Surprisingly, we found that ursolic acid decreased the apparent molecular weight of ICAM-1 and altered the structures of N-linked oligosaccharides bound to ICAM-1. Ursolic acid induced the accumulation of ICAM-1 in the endoplasmic reticulum, which was linked mainly to high-mannose-type glycans. Moreover, in ursolic-acid-treated cells, the Golgi apparatus was fragmented into pieces and distributed over the cells. Thus, our results reveal that ursolic acid inhibits intracellular trafficking of proteins and induces the accumulation of ICAM-1 linked to high-mannose-type glycans in the endoplasmic reticulum.

No MeSH data available.


Related in: MedlinePlus

Ursolic acid induces morphological changes of Golgi apparatus. A549 cells were incubated in the presence or absence of ursolic acid (50 μM) for 6 h. Cells were stained for GM130 (red), and the shapes of the Golgi apparatus were observed under a fluorescence light microscope (A). Scale bars represent 20 μm. The number of cells harboring a normal type, a disrupted type, and other types of the Golgi apparatus was measured (B). Cell number (%) is represented by the means ± S.D. of three independent experiments. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
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f0025: Ursolic acid induces morphological changes of Golgi apparatus. A549 cells were incubated in the presence or absence of ursolic acid (50 μM) for 6 h. Cells were stained for GM130 (red), and the shapes of the Golgi apparatus were observed under a fluorescence light microscope (A). Scale bars represent 20 μm. The number of cells harboring a normal type, a disrupted type, and other types of the Golgi apparatus was measured (B). Cell number (%) is represented by the means ± S.D. of three independent experiments. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Mentions: The subcellular localization of ICAM-1 was further analyzed by confocal microscopy (Figs. S3 and S4 for lower magnification images, and Fig. 4A and B for higher magnification images of representative cells). GM130 and calnexin are localized in the Golgi apparatus and the ER, respectively [35,36]. Control A549 cells did not express ICAM-1, whereas IL-1α stimulation induced the expression of ICAM-1 over the whole cell including the cell periphery (Fig. 4A and B). Only a part of ICAM-1 was co-localized with GM130 and calnexin in IL-1α-stimulated cells (Fig. 4A and B). This staining pattern suggests that a large part of ICAM-1 is transported from the Golgi apparatus and present on the cell surface. When A549 cells were preincubated with ursolic acid and then incubated with IL-1α, ICAM-1 was accumulated around the nucleus and co-localized markedly with calnexin but barely with GM130 (Fig. 4A and B). Thus, these results indicate that ursolic acid induces the accumulation of ICAM-1 in the ER. In addition, we observed that the Golgi apparatus is fragmented and scattered over the cells upon exposure to ursolic acid regardless of the presence or absence of IL-1α (Fig. 4A). To quantify the morphological changes of the Golgi apparatus, the shapes of the Golgi apparatus were classified into a normal type, a disrupted type and other types by using fluorescent microscopy. Ursolic acid significantly decreased the percentage of cells harboring the normal Golgi apparatus, and conversely increased the percentage of cells harboring the disrupted Golgi apparatus (Fig. 5A and B).


Ursolic acid, a natural pentacyclic triterpenoid, inhibits intracellular trafficking of proteins and induces accumulation of intercellular adhesion molecule-1 linked to high-mannose-type glycans in the endoplasmic reticulum.

Mitsuda S, Yokomichi T, Yokoigawa J, Kataoka T - FEBS Open Bio (2014)

Ursolic acid induces morphological changes of Golgi apparatus. A549 cells were incubated in the presence or absence of ursolic acid (50 μM) for 6 h. Cells were stained for GM130 (red), and the shapes of the Golgi apparatus were observed under a fluorescence light microscope (A). Scale bars represent 20 μm. The number of cells harboring a normal type, a disrupted type, and other types of the Golgi apparatus was measured (B). Cell number (%) is represented by the means ± S.D. of three independent experiments. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
© Copyright Policy - CC BY-NC-ND
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3958921&req=5

f0025: Ursolic acid induces morphological changes of Golgi apparatus. A549 cells were incubated in the presence or absence of ursolic acid (50 μM) for 6 h. Cells were stained for GM130 (red), and the shapes of the Golgi apparatus were observed under a fluorescence light microscope (A). Scale bars represent 20 μm. The number of cells harboring a normal type, a disrupted type, and other types of the Golgi apparatus was measured (B). Cell number (%) is represented by the means ± S.D. of three independent experiments. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Mentions: The subcellular localization of ICAM-1 was further analyzed by confocal microscopy (Figs. S3 and S4 for lower magnification images, and Fig. 4A and B for higher magnification images of representative cells). GM130 and calnexin are localized in the Golgi apparatus and the ER, respectively [35,36]. Control A549 cells did not express ICAM-1, whereas IL-1α stimulation induced the expression of ICAM-1 over the whole cell including the cell periphery (Fig. 4A and B). Only a part of ICAM-1 was co-localized with GM130 and calnexin in IL-1α-stimulated cells (Fig. 4A and B). This staining pattern suggests that a large part of ICAM-1 is transported from the Golgi apparatus and present on the cell surface. When A549 cells were preincubated with ursolic acid and then incubated with IL-1α, ICAM-1 was accumulated around the nucleus and co-localized markedly with calnexin but barely with GM130 (Fig. 4A and B). Thus, these results indicate that ursolic acid induces the accumulation of ICAM-1 in the ER. In addition, we observed that the Golgi apparatus is fragmented and scattered over the cells upon exposure to ursolic acid regardless of the presence or absence of IL-1α (Fig. 4A). To quantify the morphological changes of the Golgi apparatus, the shapes of the Golgi apparatus were classified into a normal type, a disrupted type and other types by using fluorescent microscopy. Ursolic acid significantly decreased the percentage of cells harboring the normal Golgi apparatus, and conversely increased the percentage of cells harboring the disrupted Golgi apparatus (Fig. 5A and B).

Bottom Line: By contrast, ursolic acid exerted weak inhibitory effects on the IL-1α-induced ICAM-1 expression at the protein level.Surprisingly, we found that ursolic acid decreased the apparent molecular weight of ICAM-1 and altered the structures of N-linked oligosaccharides bound to ICAM-1.Thus, our results reveal that ursolic acid inhibits intracellular trafficking of proteins and induces the accumulation of ICAM-1 linked to high-mannose-type glycans in the endoplasmic reticulum.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan.

ABSTRACT
Ursolic acid (3β-hydroxy-urs-12-en-28-oic acid) is a natural pentacyclic triterpenoid that is present in many plants, including medicinal herbs, and foods. Ursolic acid was initially identified as an inhibitor of the expression of intercellular adhesion molecule-1 (ICAM-1) in response to interleukin-1α (IL-1α). We report here a novel biological activity: ursolic acid inhibits intracellular trafficking of proteins. Ursolic acid markedly inhibited the IL-1α-induced cell-surface ICAM-1 expression in human cancer cell lines and human umbilical vein endothelial cells. By contrast, ursolic acid exerted weak inhibitory effects on the IL-1α-induced ICAM-1 expression at the protein level. Surprisingly, we found that ursolic acid decreased the apparent molecular weight of ICAM-1 and altered the structures of N-linked oligosaccharides bound to ICAM-1. Ursolic acid induced the accumulation of ICAM-1 in the endoplasmic reticulum, which was linked mainly to high-mannose-type glycans. Moreover, in ursolic-acid-treated cells, the Golgi apparatus was fragmented into pieces and distributed over the cells. Thus, our results reveal that ursolic acid inhibits intracellular trafficking of proteins and induces the accumulation of ICAM-1 linked to high-mannose-type glycans in the endoplasmic reticulum.

No MeSH data available.


Related in: MedlinePlus