The G protein-coupled oestrogen receptor 1 agonist G-1 disrupts endothelial cell microtubule structure in a receptor-independent manner
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The G protein-coupled oestrogen receptor GPER1, also known as GPR30, has been implicated in oestrogen signalling, but the physiological importance of GPER1 is not fully understood. The GPER1 agonist G-1 has become an important tool to assess GPER1-mediated cellular effects. Here, we report that this substance, besides acting via GPER1, affects the microtubule network in endothelial cells. Treatment with G-1 (3 μM) for 24 h reduced DNA synthesis by about 60 % in mouse microvascular endothelial bEnd.3 cells. Treatment with 3 μM G-1 prevented outgrowth of primary endothelial cells from mouse aortic explants embedded in Matrigel. Treatment with G-1 (0.3–3 μM) for 24 h disrupted bEnd.3 cell and HUVEC microtubule structure in a concentration-dependent manner as assessed by laser-scanning confocal immunofluorescence microscopy. G-1-induced (3 μM) disruption of microtubule was observed also after acute (3 and 6 h) treatment and in the presence of the protein synthesis inhibitor cycloheximide. Disruption of microtubules by 3 μM G-1 was observed in aortic smooth muscle cells obtained from both GPER1 knockout and wild-type mice, suggesting that G-1 influences microtubules through a mechanism independent of GPER1. G-1 dose dependently (10–50 μM) stimulated microtubule assembly in vitro. On the other hand, microtubules appeared normal in the presence of 10–50 μM G-1 as determined by electron microscopy. We suggest that G-1-promoted endothelial cell anti-proliferation is due in part to alteration of microtubule organization through a mechanism independent of GPER1. This G-1-promoted mechanism may be used to block unwanted endothelial cell proliferation and angiogenesis such as that observed in, e.g. cancer.
KeywordsEndothelial cells G-1 GPR30 Microtubule Proliferation Tubulin
This study was supported by grants from the Swedish Research Council, the Swedish Dental Society, the Greta and Johan Kocks Foundation, the Sven and Lilly Thuréus Foundation and the Vascular Wall Programme at Lund University. We thank Dr. Mary Ann Jordan of the University of California at Santa Barbara for her thoughtful advice. Supported in part by a grant to RFL from the United States Department of Defence Breast Cancer Research Program W81XWH-10-1-0903. RFL and VP gratefully acknowledge the support of the Cancer Therapy and Research Center at the University of Texas Health Science Center San Antonio, an NCI-designated Cancer Center.
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