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Role of heat shock protein 70 in induction of stress fiber formation in rat arterial endothelial cells in response to stretch stress.

Luo SS, Sugimoto K, Fujii S, Takemasa T, Fu SB, Yamashita K - Acta Histochem Cytochem (2007)

Bottom Line: In contrast, treatment with quercetin, an HSP 70 inhibitor, inhibited both upregulation of endothelial HSP 70 and formation of SFs in response to tensile stress.In addition, treatment of stretched ECs with cytochalasin D, which disrupts SF formation, did not adversely affect stretch-induced upregulation of endothelial HSP 70.Our data suggest that endothelial HSP 70 plays an important role in inducing SF formation in response to tensile stress.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Anatomy, Nippon Medical School, Tokyo 113-8602, Japan.

ABSTRACT
We investigated the mechanism by which endothelial cells (ECs) resist various forms of physical stress using an experimental system consisting of rat arterial EC sheets. Formation of actin stress fibers (SFs) and expression of endothelial heat-shock stress proteins (HSPs) in response to mechanical stretch stress were assessed by immunofluorescence microscopy. Stretch stimulation increased expression of HSPs 25 and 70, but not that of HSP 90. Treatment with SB203580, a p38 MAP kinase inhibitor that acts upstream of the HSP 25 activation cascade, or with geldanamycin, an inhibitor of HSP 90, had no effect on the SF formation response to mechanical stretch stress. In contrast, treatment with quercetin, an HSP 70 inhibitor, inhibited both upregulation of endothelial HSP 70 and formation of SFs in response to tensile stress. In addition, treatment of stretched ECs with cytochalasin D, which disrupts SF formation, did not adversely affect stretch-induced upregulation of endothelial HSP 70. Our data suggest that endothelial HSP 70 plays an important role in inducing SF formation in response to tensile stress.

No MeSH data available.


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Effects of HSP inhibitors on stretch-stress-induced SF formation in ECs from the common iliac artery as revealed by rhodamine-phalloidin staining. The arterial segments were treated with inhibitors while in the stretched state (30% amplitude, 1 hr). (A) Vehicle control (DMSO); (B) 5 µg/ml geldanamycin; (C) 50 µM SB203580; (D) 1 µM quercetin; (E) 50 µM quercetin; (F) 100 µM quercetin. Stretch-induced SF formation was not affected by the presence of either geldanamycin (B) or SB203580 (C). In contrast, quercetin inhibited SF formation in a concentration-dependent manner (D, E, F). Images A–F are shown at the same magnification; bar=20 µm.
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Figure 6: Effects of HSP inhibitors on stretch-stress-induced SF formation in ECs from the common iliac artery as revealed by rhodamine-phalloidin staining. The arterial segments were treated with inhibitors while in the stretched state (30% amplitude, 1 hr). (A) Vehicle control (DMSO); (B) 5 µg/ml geldanamycin; (C) 50 µM SB203580; (D) 1 µM quercetin; (E) 50 µM quercetin; (F) 100 µM quercetin. Stretch-induced SF formation was not affected by the presence of either geldanamycin (B) or SB203580 (C). In contrast, quercetin inhibited SF formation in a concentration-dependent manner (D, E, F). Images A–F are shown at the same magnification; bar=20 µm.

Mentions: The relationship between SF formation and HSP expression was investigated by treating the arterial ECs with one of the following inhibitors before stretching: SB203580 (1–50 µM), a p38 MAP kinase inhibitor that acts upstream of the HSP 25 activation cascade; geldanamycin (5 µg/ml), an inhibitor of HSP 90; and quercetin (1–100 µM), an inhibitor of HSP 70. The number of SFs formed upon tensile stress loading in ECs from all the sources examined was unaffected by treatment with SB203580 or geldanamycin (Fig. 6A–C). In contrast, quercetin appeared to inhibit SF formation in a concentration-dependent manner (Fig. 6D–F). In ECs in the middle parts of the abdominal aorta and the common iliac artery, SF formation was blocked when quercetin was present at 100 µM during stretching, and the SF-positive frequency in stretched, quercetin-treated ECs was about the same as that of non-stretched control ECs (compare Figs. 2 and 7). The HSP 70 immunofluorescence signal was clearly diminished in quercetin-treated ECs, as compared to non-treated ECs under stretch stress conditions (Figs. 8C and 9).


Role of heat shock protein 70 in induction of stress fiber formation in rat arterial endothelial cells in response to stretch stress.

Luo SS, Sugimoto K, Fujii S, Takemasa T, Fu SB, Yamashita K - Acta Histochem Cytochem (2007)

Effects of HSP inhibitors on stretch-stress-induced SF formation in ECs from the common iliac artery as revealed by rhodamine-phalloidin staining. The arterial segments were treated with inhibitors while in the stretched state (30% amplitude, 1 hr). (A) Vehicle control (DMSO); (B) 5 µg/ml geldanamycin; (C) 50 µM SB203580; (D) 1 µM quercetin; (E) 50 µM quercetin; (F) 100 µM quercetin. Stretch-induced SF formation was not affected by the presence of either geldanamycin (B) or SB203580 (C). In contrast, quercetin inhibited SF formation in a concentration-dependent manner (D, E, F). Images A–F are shown at the same magnification; bar=20 µm.
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Related In: Results  -  Collection

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Figure 6: Effects of HSP inhibitors on stretch-stress-induced SF formation in ECs from the common iliac artery as revealed by rhodamine-phalloidin staining. The arterial segments were treated with inhibitors while in the stretched state (30% amplitude, 1 hr). (A) Vehicle control (DMSO); (B) 5 µg/ml geldanamycin; (C) 50 µM SB203580; (D) 1 µM quercetin; (E) 50 µM quercetin; (F) 100 µM quercetin. Stretch-induced SF formation was not affected by the presence of either geldanamycin (B) or SB203580 (C). In contrast, quercetin inhibited SF formation in a concentration-dependent manner (D, E, F). Images A–F are shown at the same magnification; bar=20 µm.
Mentions: The relationship between SF formation and HSP expression was investigated by treating the arterial ECs with one of the following inhibitors before stretching: SB203580 (1–50 µM), a p38 MAP kinase inhibitor that acts upstream of the HSP 25 activation cascade; geldanamycin (5 µg/ml), an inhibitor of HSP 90; and quercetin (1–100 µM), an inhibitor of HSP 70. The number of SFs formed upon tensile stress loading in ECs from all the sources examined was unaffected by treatment with SB203580 or geldanamycin (Fig. 6A–C). In contrast, quercetin appeared to inhibit SF formation in a concentration-dependent manner (Fig. 6D–F). In ECs in the middle parts of the abdominal aorta and the common iliac artery, SF formation was blocked when quercetin was present at 100 µM during stretching, and the SF-positive frequency in stretched, quercetin-treated ECs was about the same as that of non-stretched control ECs (compare Figs. 2 and 7). The HSP 70 immunofluorescence signal was clearly diminished in quercetin-treated ECs, as compared to non-treated ECs under stretch stress conditions (Figs. 8C and 9).

Bottom Line: In contrast, treatment with quercetin, an HSP 70 inhibitor, inhibited both upregulation of endothelial HSP 70 and formation of SFs in response to tensile stress.In addition, treatment of stretched ECs with cytochalasin D, which disrupts SF formation, did not adversely affect stretch-induced upregulation of endothelial HSP 70.Our data suggest that endothelial HSP 70 plays an important role in inducing SF formation in response to tensile stress.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Anatomy, Nippon Medical School, Tokyo 113-8602, Japan.

ABSTRACT
We investigated the mechanism by which endothelial cells (ECs) resist various forms of physical stress using an experimental system consisting of rat arterial EC sheets. Formation of actin stress fibers (SFs) and expression of endothelial heat-shock stress proteins (HSPs) in response to mechanical stretch stress were assessed by immunofluorescence microscopy. Stretch stimulation increased expression of HSPs 25 and 70, but not that of HSP 90. Treatment with SB203580, a p38 MAP kinase inhibitor that acts upstream of the HSP 25 activation cascade, or with geldanamycin, an inhibitor of HSP 90, had no effect on the SF formation response to mechanical stretch stress. In contrast, treatment with quercetin, an HSP 70 inhibitor, inhibited both upregulation of endothelial HSP 70 and formation of SFs in response to tensile stress. In addition, treatment of stretched ECs with cytochalasin D, which disrupts SF formation, did not adversely affect stretch-induced upregulation of endothelial HSP 70. Our data suggest that endothelial HSP 70 plays an important role in inducing SF formation in response to tensile stress.

No MeSH data available.


Related in: MedlinePlus