Vascular injury. FoxM1 is a member of the mammalian fox family of transcription factors that share homology in their winged helix DNA-binding domains [9?1]. FoxM1 is expressed in proliferating cells including cancer cells, where it controls cell cycle progression into DNA replication (G1/S) and mitosis (G2/M), and silenced in terminally differentiated cells [12?5]. FoxM1 is essential for transcription expression of the S-phase kinaseassociated protein 2 and Cdk subunit 1 to regulate the degradation of Cdk inhibitor proteins p21Cip1 and p27Kip1 during the G1/S transition [13]. FoxM1 also controls the transcription of genes critical for G2/M and mitotic progression including cyclin B1,Cdc25B and Cdc25C phosphatases, polo-like kinase 1 and aurora kniase [13,14]. FoxM1 transcriptional activity requires phosphorylation at Thr596 by either the S-phase or M-phase Cdk-cyclin complexes and subsequent recruitment of p300/CBP coactivator proteins [16]. In response to various stimuli, FoxM1 expression is induced in several cell types in vivo including hepatocytes and lung epithelial cells and plays an important role in liver regeneration and alveolar repair, respectively [13,17]. FoxM1 expression is also markedly induced in the pulmonary vascular endothelial cells (EC) following lipopolysaccharide (LPS) challenge [18]. Intriguingly, FoxM1 is only induced during the recovery phase following LPS challenge. Employing the mouse model with EC-restricted disruption of FoxM1 (FoxM1 CKO), we have shown the critical role of FoxM1 in regulating endothelial proliferation and endothelial repair following lung vascular injury induced 1480666 by LPS challenge [18]. FoxM1 CKO mice exhibit persistent lung vascular leakiness and increased mortality following LPS challenge. We have also shown that FoxM1 is essential for CI-1011 site re-annealing of endothelial adherens junction complex and thereby restoration of endothelial barrier integrity through transcriptional control of b-catenin expression [19]. b-catenin is the integral protein of CASIN adherent junctions [20,21]. However, it remains unclear whether FoxM1 expressionFoxM1 Promotes Endothelial Repairis sufficient to promote endothelial repair following lung injury. Especially, it is unknown if FoxM1 is critical for endothelial repair following polymicrobial sepsis induced by cecal ligation and puncture (CLP), a well-recognized clinically relevant rodent model of sepsis [22?4]. Here, employing FoxM1 transgenic mice (FoxM1 Tg) as well as FoxM1 CKO mice, we show that FoxM1 expression is necessary and sufficient to promote endothelial regeneration and barrier repair following lung injury induced by CLP challenge.homogenates were centrifuged again. The supernatants were assayed for MPO activity using kinetics readings for 3 15857111 min and absorbance was measured at 460 nm. The results were presented as DOD460/min/g lung tissue.Histological AnalysisFollowing PBS perfusion, the lung tissues were fixed for 5 min by instillation of 10 PBS-buffered formalin through trachea at a trans-pulmonary pressure of 15 cm H2O. After tracheal ligation, the lungs were fixed with 10 PBS-buffered formalin overnight at 4uC. After paraffin embedding process, the tissues were sectioned at 5 mm thick and stained with H E.Materials and Methods MiceFoxM1 transgenic mice were obtained from Dr. Robert H. Costa at the University of Illinois College of Medicine [25]. FoxM1 CKO mice were previously made in our laboratory (18, 19). All mice were bred and maintained in the As.Vascular injury. FoxM1 is a member of the mammalian fox family of transcription factors that share homology in their winged helix DNA-binding domains [9?1]. FoxM1 is expressed in proliferating cells including cancer cells, where it controls cell cycle progression into DNA replication (G1/S) and mitosis (G2/M), and silenced in terminally differentiated cells [12?5]. FoxM1 is essential for transcription expression of the S-phase kinaseassociated protein 2 and Cdk subunit 1 to regulate the degradation of Cdk inhibitor proteins p21Cip1 and p27Kip1 during the G1/S transition [13]. FoxM1 also controls the transcription of genes critical for G2/M and mitotic progression including cyclin B1,Cdc25B and Cdc25C phosphatases, polo-like kinase 1 and aurora kniase [13,14]. FoxM1 transcriptional activity requires phosphorylation at Thr596 by either the S-phase or M-phase Cdk-cyclin complexes and subsequent recruitment of p300/CBP coactivator proteins [16]. In response to various stimuli, FoxM1 expression is induced in several cell types in vivo including hepatocytes and lung epithelial cells and plays an important role in liver regeneration and alveolar repair, respectively [13,17]. FoxM1 expression is also markedly induced in the pulmonary vascular endothelial cells (EC) following lipopolysaccharide (LPS) challenge [18]. Intriguingly, FoxM1 is only induced during the recovery phase following LPS challenge. Employing the mouse model with EC-restricted disruption of FoxM1 (FoxM1 CKO), we have shown the critical role of FoxM1 in regulating endothelial proliferation and endothelial repair following lung vascular injury induced 1480666 by LPS challenge [18]. FoxM1 CKO mice exhibit persistent lung vascular leakiness and increased mortality following LPS challenge. We have also shown that FoxM1 is essential for re-annealing of endothelial adherens junction complex and thereby restoration of endothelial barrier integrity through transcriptional control of b-catenin expression [19]. b-catenin is the integral protein of adherent junctions [20,21]. However, it remains unclear whether FoxM1 expressionFoxM1 Promotes Endothelial Repairis sufficient to promote endothelial repair following lung injury. Especially, it is unknown if FoxM1 is critical for endothelial repair following polymicrobial sepsis induced by cecal ligation and puncture (CLP), a well-recognized clinically relevant rodent model of sepsis [22?4]. Here, employing FoxM1 transgenic mice (FoxM1 Tg) as well as FoxM1 CKO mice, we show that FoxM1 expression is necessary and sufficient to promote endothelial regeneration and barrier repair following lung injury induced by CLP challenge.homogenates were centrifuged again. The supernatants were assayed for MPO activity using kinetics readings for 3 15857111 min and absorbance was measured at 460 nm. The results were presented as DOD460/min/g lung tissue.Histological AnalysisFollowing PBS perfusion, the lung tissues were fixed for 5 min by instillation of 10 PBS-buffered formalin through trachea at a trans-pulmonary pressure of 15 cm H2O. After tracheal ligation, the lungs were fixed with 10 PBS-buffered formalin overnight at 4uC. After paraffin embedding process, the tissues were sectioned at 5 mm thick and stained with H E.Materials and Methods MiceFoxM1 transgenic mice were obtained from Dr. Robert H. Costa at the University of Illinois College of Medicine [25]. FoxM1 CKO mice were previously made in our laboratory (18, 19). All mice were bred and maintained in the As.