STUDIES OF PRODUCTION AND ANALYSIS OF CAVEOLIN-3 AND DYSTROPHIN DEFICIENT MOUSE LINE

肌营养不良症的致病基因约有30个，其中包括肌营养不良蛋白（Dystrophin）和小凹蛋白-3（CAVEOLIN-3）突变基因。以前，我们通过基因打靶技术产生了CAVEOLIN-3缺陷小鼠。在本研究中，我们通过Dystrophin缺陷型MDX小鼠和Caveolin-3缺陷型小鼠的杂交，建立了Dystrophin和Caveolin-3基因均缺陷的小鼠品系。利用这条线，我们试图阐明这些蛋白质在肌肉营养不良病理学中的作用。我们发现MDX和这条线小鼠肌肉显示相似的组织学。然而，当分析基因表达时，我们在这条线上发现了有趣的结果。骨桥蛋白基因表达在肌再生中增加，但在Caveolin-3缺陷的肌中却大大减少。最后，它在MDX肌肉中得到了极大的增强。通过使用双缺陷小鼠进一步证实了Caveolin-3参与骨桥蛋白基因的表达。骨桥蛋白基因在MDX肌中的表达水平比野生型肌高30-55倍，而在双缺陷小鼠中仅为野生型肌的5-14倍。因此，肌营养不良蛋白和小凹蛋白-3的缺乏对骨桥蛋白基因表达具有相反的影响，从而对肌肉再生具有相反的影响，尽管这两种蛋白的缺乏导致肌肉营养不良。

APPROXIMATELY 30GENES, INCLUDING DYSTROPHIN AND CAVEOLIN-3 MUTANT GENES, ARE KNOWN AS THE CAUSES OF MUSCULAR DYSTROPHIES THAT SHOW DEGENERATION, NECROSIS AND REGENERATION OF MUSCLE FIBERS. PREVIOUSLY, WE PRODUCED CAVEOLIN-3 DEFICIENT MICE BY GENE TARGETING TECHNIQUES. IN THIS STUDY, WE ESTABLISHED A MOUSE LINE HAVING DEFECTS IN BOTH DYSTROPHIN AND CAVEOLIN-3 GENES, BY CROSS-BLEEDING OF DYSTROPHIN DEFICIENT MDX MICE AND CAVEOLIN-3 DEFICIENT MICE. USING THIS LINE, WE TRIED TO CLARIFY THE ROLES OF THESE PROTEINS IN THE PATHOLOGY OF MUSCULAR DYSTROPHY. WE FOUND THAT MDX AND THIS LINE MOUSE MUSCLES SHOWED SIMILAR HISTOLOGY. HOWEVER, WE FOUND INTERESTING RESULTS IN THIS LINE, WHEN GENE EXPRESSION WAS ANALYZED. OSTEOPONTIN GENE EXPRESSION WHICH IS KNOWN TO INCREASE ON MUSCLE REGENERATION WAS GREATLY DECREASED IN CAVEOLIN-3 DEFICIENT MUSCLE. IN CONTRAST, IT WAS EXTREMELY ENHANCED IN MDX MUSCLE. PARTICIPATION OF CAVEOLIN-3 IN THE OSTEOPONTIN GENE EXPRESSION WAS FURTHER CLARIFIED BY USING THE DOUBLE DEFICIENT MICE. IN MDX MUSCLE, OSTEOPONTIN GENE EXPRESSION LEVEL INCREASED TO 30-55 TIMES HIGHER THAN THAT OF WILD TYPE MUSCLE, WHEREAS IT RETAINED AT 5-14 TIMES IN THE DOUBLE DEFICIENT MICE. THEREFORE, ABSENCE OF DYSTROPHIN AND CAVEOLIN-3 HAS THE INVERSE EFFECTS ON THE OSTEOPONTIN GENE EXPRESSION AND THUS FOR MUSCLE REGENERATION, ALTHOUGH THE ABSENCE OF EITHER PROTEIN RESULTS IN MUSCULAR DYSTROPHY.