Analysis of Mutated SERCA2b transgenic mouse

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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