Members of the Foxo family, Foxo1 (Fkhr), Foxo3 (Fkhrl1), and Foxo4 (Afx), are mammalian homologs of daf-16, which influences life span and energy metabolism in Caenorhabditis elegans. Mammalian FOXO proteins also play important roles in cell cycle arrest, apoptosis, stress resistance, and energy metabolism. In this study, we generated Foxo1-deficient mice to investigate the physiological role of FOXO1. The Foxo1-deficient mice died around embryonic day 11 because of defects in the branchial arches and remarkably impaired vascular development of embryos and yolk sacs. In vitro differentiation of embryonic stem cells demonstrated that endothelial cells derived from wild-type and Foxo1-deficient embryonic stem cells were able to produce comparable numbers of colonies supported by a layer of OP9 stromal cells. Although the morphology of the endothelial cell colonies was identical in both genotypes in the absence of exogenous vascular endothelial growth factor (VEGF), Foxo1-deficient endothelial cells showed a markedly different morphological response compared with wild-type endothelial cells in the presence of exogenous VEGF. These results suggest that Foxo1 is essential to the ability of endothelial cells to respond properly to a high dose of VEGF, thereby playing a critical role in normal vascular development.

A forkhead-type transcription factor, DAF-16, is located in the most downstream part of the insulin signalling pathway via PI3K (phosphoinositide 3-kinase). It is essential for the extension of life-span and is also involved in dauer formation induced by food deprivation in Caenorhabditis elegans. In the present study, we addressed whether or not FOXO members AFX, FKHR (forkhead homologue in rhabdomyosarcoma) and FKHRL1 (FKHR-like protein 1), mammalian counterparts of DAF-16, are involved in starvation stress. We found a remarkable selective induction of FKHR and FKHRL1 transcripts in skeletal muscle of mice during starvation. The induction of FKHR gene expression was observed at 6 h after food deprivation, peaked at 12 h, and returned to the basal level by 24 h of refeeding. The induction was also found in skeletal muscle of mice with glucocorticoid treatment. Moreover, we found that the levels of PDK4 (pyruvate dehydrogenase kinase 4) gene expression were up-regulated through the direct binding of FKHR to the promoter region of the gene in C2C12 cells. These results suggest that FKHR has an important role in the regulation of energy metabolism, at least in part, through the up-regulation of PDK4 gene expression in skeletal muscle during starvation.

Background:We isolated tumour endothelial cells (TECs), demonstrated their abnormalities, compared gene expression profiles of TECs and normal endothelial cells (NECs) by microarray analysis and identified several genes upregulated in TECs. We focused on the gene encoding biglycan, a small leucine-rich repeat proteoglycan. No report is available on biglycan expression or function in TECs.Methods:The NEC and TEC were isolated. We investigated the biglycan expression and function in TECs. Western blotting analysis of biglycan was performed on sera from cancer patients.Results:Biglycan expression levels were higher in TECs than in NECs. Biglycan knockdown inhibited cell migration and caused morphological changes in TECs. Furthermore, immunostaining revealed strong biglycan expression in vivo in human tumour vessels, as in mouse TECs. Biglycan was detected in the sera of cancer patients but was hardly detected in those of healthy volunteers.Conclusion:These findings suggested that biglycan is a novel TEC marker and a target for anti-angiogenic therapy.

Tumor angiogenesis is necessary for progression and metastasis of solid tumor. Tumor blood vessels are morphologically different from their normal counterparts. In this study, we isolated tumor endothelial cells (TECs) and revealed their abnormalities. We have compared the gene expression profiles of TECs and normal endothelial cells (NECs) by microarray analysis and found that several genes were upregulated in TECs. Expression of the chemokine receptor CXCR7 mRNA was higher in TECs than in NECs. However, information regarding the expression of CXCR7 in the tumor vessels of renal cell carcinoma is limited. CXCR7 and its ligand CXCL12 have been implicated in tumor cell survival. In this study, the expression of CXCR7 in the tumor vessels of renal cell carcinoma (RCC) was investigated. Real-time PCR revealed higher expression level of CXCR7 in cultured TECs than in cultured NECs. Furthermore, similar to mouse TECs, immunostaining revealed strong expression of CXCR7 in vivo in human tumor vessels. These findings suggest that CXCR7 is a novel TEC marker and a target for antiangiogenic therapy for RCC.

In C. elegans, insulin-like hormone signal pathway plays a significant role in longevity. In particular, daf-16 gene product is indispensable factor for this lifespan-extension. This signal pathway is critical for dauer formation, which is a similar state to hibernation in mammals. We examined the expression level of mammalian daf-16 homologues, Foxo 1,3, and 4 (FKHR, FKHRL1, and AFX) mRNAs in the rat skeletal muscles during aging and in 30% caloric restricted of ad libitum fed. The expression level of AFX mRNA was significantly higher at 6 and 12 months than at 3 and 26 months, and FKHRL1 expression was significantly higher at 6 months than at 3 and 26 months but FKHR expression showed no significant change with age. We observed a characteristic expression of AFX and FKHR mRNAs to be significantly higher in the second day in caloric restriction by every-other-day feeding than in ad libitum fed. This suggests that caloric restriction may increase the expression of FKHR-family genes and prevent the aging process in the skeletal muscles.