Functional Analysis of Basement Membrane Collagen Genes

点击翻译按钮获取中文摘要

By analyzing Col4a knockout mice, it is now possible to predict the biological function of α(IV) chains in vivo. We have now knockout mice of two strains: col4a3 and col4a6. Since we have evidence that there are major three molecular forms in basement membranes: (α1)2α2, α3α4α5, and (α5)2α6, it is now possible to set-up experiments to presume in vivo function of several α chains. We also set-up international collaboration to create another new project of gene targeting for col4α1 or col4α2, which makes it possible to make mice without type IV collagen.We have solved problems of which of the 6 α(IV) chains can make molecules. We raised monoclonal antibodies specific for α(IV) chains. By using these 6 antibodies, we came to the conclusion that there are at least three molecular forms as mentioned above: (α1)2α2, α3α4α5, and (α5)2α6. New biochemical analysis using antibodies that recognize native chains made possible to immunoprecipitate specific molecules when they are digested by pure bacterial collagenase. The products run on SDS-PAGE were analyzed by other monoclonal antibodies that recognize now denatured α-chains by Western blots. This now method concluded that our prediction from immunocytochemistry was indeed true. In other words, there were three (α1)2α2, α3α4α5, and (α5)2α6 molecules. By this method, we analyzed basement membranes from renal glomeruli and bladder and aortic smooth muscle cells.Specialized basement membrane from glomeruli was analyzed to contain supramolecular aggregates of (α1)2α2 and α3α4α5 molecules. The function of it is to filter blood to create urine. The similar phenomenon is found in choroid plexus in the brain. We analyzed it and found that it contains also the same compositions as glomerulus.