Prominent beta-5 gene expression in the cardiovascular system and in the cartilaginous primordiae of the skeleton during mouse development

The alpha v beta (alpha(v)beta5) heterodimer has been implicated in many biological functions, including angiogenesis. We report the beta5 gene expression pattern in embryonic and foetal mouse tissues as determined by Northern blotting and in situ hybridization. During the earliest stages, beta5 mRNA is widespread in the mesoderm. During later developmental stages, it remains mostly confined to tissues of mesodermal origin, although probable inductive effects trigger shifts of beta5 gene expression from some mesenchymatous to epithelial structures. This was observed in the teeth, skin, kidneys, and gut. Of physiological importance is the beta5 labeling in the developing cardiovascular and respiratory systems and cartilages. Furthermore, early beta5 gene expression was observed within the intra- and extraembryonic sites of hematopoiesis. This suggests a major role for beta5 in the hematopoietic and angiogenic stem cells and thus in the development of the vascular system. Later, the beta5 gene was expressed in endothelial cells of the vessels developing both by angiogenesis and vasculogenesis in the lung, heart, and kidneys. Moreover, the beta5 hybridization signal was detected in developing cartilages but not in ossified or ossifying bones. beta5-Integrin is a key integrin involved in angiogenesis, vasculogenesis, hematopoiesis, and bone formation.

In vivo adenovirus-mediated delivery of a uPA/uPAR antagonist reduces retinal neovascularization in a mouse model of retinopathy

Diabetic retinopathy and retinopathy of prematurity are among the leading causes of vision impairment throughout the world. Both diseases are characterized by pathological angiogenesis, which severely impairs vision. Extracellular proteinases play important roles in endothelial cell migration during angiogenesis. Amino-terminal fragment (ATF) is an angiostatic molecule that targets the uPA/uPAR system and inhibits endothelial cell migration. The angiostatic effect of ATF has been demonstrated in models of cancer, but has never been assessed in pathological retinal neovascularization. Endostatin also has angiostatic effects on tumor growth and retinal neovascularization. We used an adenoviral vector carrying the murine ATF (AdATFHSA) or endostatin gene coupled to human serum albumin (HSA) (AdEndoHSA) to increase the half-life of the therapeutic protein in the circulation. We induced retinopathy by exposing 7-day-old mice to high levels of oxygen. They were intravitreally injected with the vectors. Local injection of AdATFHSA or AdEndoHSA reduced retinal neovascularization by 78.1 and 79.2%, respectively. Thus, the adenovirus-mediated delivery of ATFHSA or EndoHSA reduces retinal neovascularization in a mouse model of hypoxia-induced neovascularization.

Effect of overexpression of human apo A-I in C57BL/6 and C57BL/6 apo E-deficient mice on 2 lipoprotein-associated enzymes, platelet-activating factor acetylhydrolase and paraoxonase. Comparison of adenovirus-mediated human apo A-I gene transfer and human apo A-I transgenesis

Various mechanisms may contribute to the antiatherogenic potential of apolipoprotein A-I (apo A-I) and high density lipoproteins (HDLs). Therefore, the effect of adenovirus-mediated human apo A-I gene transfer or human apo A-I transgenesis on platelet-activating factor acetylhydrolase (PAF-AH) and arylesterase/paraoxonase (PON1) was studied in C57BL/6 and C57BL/6 apo E(-/-) mice. Human apo A-I transgenesis in C57BL/6 mice resulted in a 4.2-fold (P<0.0001) increase of PAF-AH and a 1.7-fold (P=0.0012) increase of PON1 activity. The apo E deficiency was associated with a 1.6-fold (P=0.008) lower PAF-AH and a 2.0-fold (P=0.012) lower PON1 activity. Human apo A-I transgenesis in C57BL/6 apo E(-/-)mice increased PAF-AH and PON1 activity by 2.1-fold (P=0.01) and 2.5-fold (P=0.029), respectively. After adenovirus-mediated gene transfer of human apo A-I into C57BL/6 apo E(-/-)mice, a strong correlation between human apo A-I plasma levels and PAF-AH activity was observed at day 6 (r=0.92, P<0.0001). However, PON1 activity failed to increase, probably as a result of cytokine-mediated inhibition of PON 1 expression. In conclusion, this study indicates that overexpression of human apo A-I increases HDL-associated PAF-AH activity. PON1 activity was also increased in human apo A-I transgenic mice, but not after human apo A-I gene transfer, a result that was probably related to cytokine production induced in the liver by the adenoviral vectors. Increased levels of these HDL-associated enzymes may contribute to the anti-inflammatory and antioxidative potential of HDL and thereby to the protection conferred by HDL against atherothrombosis.