Analysis of Mutated SERCA2b transgenic mouse

肌内质网钙atp酶2b （SERCA2b）基因（ATP2A2）突变及其导致的SERCA2b缺陷可引起常染色体显性遗传性皮肤病，即Darier病。在引起达里尔病的各种点突变中，L321F突变是独特的，因为该突变对累积腔内钙对运输周期的反馈抑制的敏感性显著降低。我们培育的L321F转基因小鼠表型无明显异常，毛发生长明显正常。热处理和胶带剥离都不会导致Darier型棘质溶解或角化不良。这些结果表明，小鼠角化细胞中存在其他的钙稳态补偿机制，以抵消L321F的显性负作用。我们还对位于高尔基体的另一种钙泵ATP2C1进行了分析，其突变可导致另一种常染色体显性皮肤病Ha…More iley-Hailey病。免疫组织化学分析表明，ATP2C1特异性定位于基底细胞层。从培养皿中剥离角质细胞和高浓度钙处理都没有抑制ATP2C1的表达，但这两种方法都诱导了角质细胞分化标志物K10角蛋白和天花素。敲低ATP2C1诱导这些角质形成细胞的分化标记。这些结果表明，ATP2C1在基底角质形成细胞保持未分化状态中起着至关重要的作用，其减少引起分化。综上所述，我们的研究结果表明，钙稳态影响角质形成细胞的分化，而ATP2A2和ATP2C1的突变阻碍了角质形成细胞的基本过程，导致Darier病和Hailey-Hailey病，钙调节泵的动力学特性的改变会引起角质形成细胞微细胞钙稳态的不同类型的扰动，影响其分化过程。少

Mutations in the sarcoendoplasmic reticulum calcium ATPase 2b (SERCA2b) gene (ATP2A2) and the resulting defects in the SERCA2b cause an autosomal dominant genetic skin disease, Darier disease. Among the various point mutations causing Darier disease L321F mutation is unique, because this mutation shows the remarkably reduced sensitivity to the feedback inhibition of the transport cycle by accumulated luminal calcium. We have generated L321F transgenic mouse which showed no remarkable phenotype abnormality with apparently normal hair growth. Neither heat treatment nor tape-stripping ptrocedure resulted in Darier type acantholytic or dyskeratotic changes. These results indicate that other compensatory mechanism of keratinocyte calcium homeostasis exist in mouse keratinocytes to abrogate the dominant-negative effect of L321F. We have also performed analysis of ATP2C1, another calcium pump located in Golgi apparatus, the mutation of which causes another autosomal dominant skin disorder, Ha … More iley-Hailey disease. Immunohistochemical analysis disclosed that ATP2C1 is specifically localized at the basal cell layer. Neither detachment of keratinocytes from culture dish nor treatment with high concentrations of calcium suppressed ATP2C1 expression, while both procedures induced keratinocyte differentiation markers, K10 keratin and involucrin. Knockdown of ATP2C1 induced these differentiation markers of keratinocytes. These results suggest that ATP2C1 plays an essential role for basal keratinocytes to keep in the undifferentiated state and that its reduction evokes differentiation. Taken together, our results indicate that calcium homeostasis affects differentiation of keratinocytes and the mutation of ATP2A2 and ATP2C1 hampers the essential process of keratinocytes resulting in Darier disease and Hailey-Hailey disease, respectively Altered kinetic properties of calcium-regulating pumps will cause different types of perturbation in tracellular calcium homeostasis of keratinocytes affecting their differentiation process. Less