Endothelial cell–restricted disruption of FoxM1 impairs endothelial repair following LPS-induced vascular injury
You-Yang Zhao, … , Robert H. Costa, Asrar B. Malik
You-Yang Zhao, … , Robert H. Costa, Asrar B. Malik
Published September 1, 2006
Citation Information: J Clin Invest. 2006;116(9):2333-2343. https://doi.org/10.1172/JCI27154.
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Research Article Vascular biology

Endothelial cell–restricted disruption of FoxM1 impairs endothelial repair following LPS-induced vascular injury

Abstract

Recovery of endothelial integrity after vascular injury is vital for endothelial barrier function and vascular homeostasis. However, little is known about the molecular mechanisms of endothelial barrier repair following injury. To investigate the functional role of forkhead box M1 (FoxM1) in the mechanism of endothelial repair, we generated endothelial cell–restricted FoxM1-deficient mice (FoxM1 CKO mice). These mutant mice were viable and exhibited no overt phenotype. However, in response to the inflammatory mediator LPS, FoxM1 CKO mice displayed significantly protracted increase in lung vascular permeability and markedly increased mortality. Following LPS-induced vascular injury, FoxM1 CKO lungs demonstrated impaired cell proliferation in association with sustained expression of p27Kip1 and decreased expression of cyclin B1 and Cdc25C. Endothelial cells isolated from FoxM1 CKO lungs failed to proliferate, and siRNA-mediated suppression of FoxM1 expression in human endothelial cells resulted in defective cell cycle progression. Deletion of FoxM1 in endothelial cells induced decreased expression of cyclins, Cdc2, and Cdc25C, increased p27Kip1 expression, and decreased Cdk activities. Thus, FoxM1 plays a critical role in the mechanism of the restoration of endothelial barrier function following vascular injury. These data suggest that impairment in FoxM1 activation may be an important determinant of the persistent vascular barrier leakiness and edema formation associated with inflammatory diseases.

Authors

You-Yang Zhao, Xiao-Pei Gao, Yidan D. Zhao, Muhammad K. Mirza, Randall S. Frey, Vladimir V. Kalinichenko, I-Ching Wang, Robert H. Costa, Asrar B. Malik

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Figure 1

Mouse model of endothelial cell–restricted deletion of FoxM1.

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Mouse model of endothelial cell–restricted deletion of FoxM1. ...
(A) Southern blot demonstrating recombination of the FoxM1 floxed allele in endothelial cell–enriched tissues. Mouse genomic DNA (15 μg /lane) was digested with Bgl II and XbaI. The blots were probed with 3′ probe as described (13). Tie2 promoter/enhancer-driven Cre expression created a predicted 7.6-kb band in the aorta and lungs. The pseudogene band is indicated by an asterisk. (13). fl, FoxM1 floxed allele; AA, aorta; L, lung. (B) Quantitative analysis of mRNA expression of FoxM1 and FoxO1 by QRT-PCR. RNA was extracted from lungs of either FoxM1 WT or FoxM1 CKO mice. mRNA expression of FoxM1 and FoxO1 was normalized to mouse cyclophilin mRNA. There were no differences in FoxM1 mRNA levels in mice with the 3 genotypes FoxM1+/+, FoxM1fl/+, and FoxM1fl/fl; therefore, all these mice were referred to as WT mice. Data are expressed as mean ± SD, n = 3. **P < 0.05. CKO, FoxM1 CKO. (C) Quantitative analysis of FoxM1 expression in population of cells either enriched or depleted of endothelial cells. RNA was extracted from an endothelial cell–enriched primary culture (EC, passage 0) isolated from mouse lungs or from nonendothelial cell primary cultures (non-EC, passage 4), fibroblasts, and epithelial cells. Approximately 70% reduction of FoxM1 mRNA levels was detected in FoxM1 CKO EC and not in FoxM1 CKO non-EC (n = 3), indicating endothelial cell–specific knockdown of FoxM1. #P < 0.01. n = 3.