| In adults , perturbations of heart valve homeostasis will lead to diseased from acquired,'degenerative valve disease'. Degenerative valvular disease(DAVD) is the third most common cause of cardiovascular disease.It is unclear, however, concerning how the normal valve homeostasis is maintained and how valve disease is initiated in normal adults. So,notch singnal will be the key to the new therapy and prevention of heart valve diseases.But, the mechanism is still not very clear.Recently, many research groups have succeded in the establishment of transgenic mouse model of valve disease, which open a new way for human to explore the mechanisms of valve disease. RBP-JК, the transcription factor downstream of Notch receptors is essential for notch pathways and knockout RBP-JКwill block nocth signaling.Therefore,RBP-JКdeficient mouses will be the ideal modle for the research on perturbations of heart valve homeostasis.Howerer, the normal structure of mouse aortic valve have not been systemistic studied,which make it difficult for gene knockout mouse model of aortic valve disease to do proper research and evaluation .In this study, it is the the first time to do comprhensive assessment on the structure of the aortic valve in normal mice ,while the heart valve of notch gene knockout mice were compared and analyzed with the normal one,to find the function of the notch signaling pathway in the regulation of homeostasis in the valve effect and possible mechanism. It may elucidate novel treatment and prevention strategies of heart valve disease..AIMS1. To observe normal mice aortic valve morphology and ultrastructure.2. to find the function of the notch signaling pathway in the regulation of homeostasis in the valve effect and possible mechanism ..METHODS1. Adult mouse (postnatal 3 months) hearts were harvested and histological and valve morphometric analyses of the valve cells population, distribution and collagen content as well as the valve microstructure were conducted by light microscope (HE stain, immunofluorescence, Laser scanning confocal microscope and Masson's trichrome stain) and transmission electron microscope.2. Using the Cre-LoxP-mediated conditional gene deletion mouse , hearts were harvested and histological and valve morphometric analyses of the valve cells population, distribution and collagen content as well as the valve microstructure were conducted by light microscope (HE stain, immunofluorescence, Laser scanning confocal microscope and Masson's trichrome stain) and transmission electron microscope.RESULTS1. Normal aortic valve mice showed semi- transparent fiber membranes, its roots fixed in the cardiac annulus and the free edge in the lumen. The aortic valve is connected with mitral valve. The white slices of aortic valve showed changes in symmetry distribution and the middle part longer than the two ends. By 3D-doctor software, we got the three-dimensional reconstruction of the valve, sothat we can found different among the differernt local volume of the valve and found that free edge> root> the middle. The aortic valve area of normal mice was (0.1978±0.003 mm2), with a perimeter of (9.18×102±0.06×102um), the average cell number (9.75×102±0.04×102/mm2), the endothelial cell number (3.23×102±0.1×102/mm2), the intersititial cell number (5.05×102±0.07×102 /mm2), and the collagen content (21.62%±9.33%). Confocal laser scanning displayed some co-expressed CD31 andα-SMA cells under endothelium.The electron microscope showed some morphological difference between ventricular face of valve and aortic face of valve endothelium. The ventricular face of valve endothelium was flat while the aortic face of valve endothelium was square in shape. Interstitial fibroblasts were in a quiescent state, in which the cell bodies were small and long spindle-shaped, and endoplasmic reticulum and Golgi complexes were undeveloped. Extracellular matrix was collagen-rich, which was mainly concentrated in the outflow tract.2. Maladaptive Valve Remodeling in RBP-J mutation mice.Disruptionof RBP-JКinduces up-regulation of VEGFR2 and VEC proliferation.Mice lacking RBP-JКlead to VEC dysfuction and basement membrane disruption in ultrastructural. Dual-character melanocytes increased in knockout mice.Interrupt of RBP-J cause EMT in aortic valve.Mesenchymal cell proliferation and fibrosis secretion increasing.CONCLUSIONS1. In this study, the mouse aortic valve morphology were first observed in detail.Through the gross microscope ,the gross structure of mice normal aortic was similar with the human normal valve, but more tansparant than the human one. Histological and valve morphometric analyses of the valve cells population, distribution and collagen content as well as the valve microstructure were conducted by light microscope (HE stain, immunofluorescence, Laser scanning confocal microscope and Masson's trichrome stain) and transmission electron microscope. The results of this study provide some histological and morphometric data for normal mouse aortic valve structure and are useful as reference standards for future studies of mouse models of progressive aorta valve diseases.2. It was first time we used the white slice of aortic valve to locate the three-dimensional positioning of aortic valve .It was first used 3D-doctor on the three-dimensional reconstruction of mouse aortic valve, so that we can compare the local volume of the valve with the others.3. Confocal laser scanning displayed some co-expressed CD31 andα-SMA cells under endothelium, indicating the existence of epidermis-mesenchymal transformation potential cells in adult aorta valves.4. It was first that the aortic morphology of valve in adult conditional knockout Notch gene mice was compared and analyzed.We found that knockout RBP-JКin valve endothelial cells caused abnormal valve remodeling, which suggested that RBP-JКmay be the new drug therapy targets for treatment and prevention of valvular disease. These findings suggest that in adults RBP-J-mediated Notch signaling may play an essential role in the maintenance of valve homeostasis5. Knockout RBP-JКin valve endothelial cells upregulated VEGFR2 and promoted endothelial cell proliferation, which leads to heart valve endothelial cells dysfunction and basement membrane disorder in ultrastructura.So we believed that VEGFR2 is inhibited by RBP-JКto maintain the valve endothelial cell homeostasis.6. Interrupt of RBP-JКcause EMT in aortic valve,which caused mesenchymal cell proliferation and fibrosis secretion increasing.Meanwhile ,knockout RBP-JКlead to dual-character melanocytes increased which maybe fuction in valve remolding...
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