Similar Ca(2+)-signaling properties in keratinocytes and in COS-1 cells overexpressing the secretory-pathway Ca(2+)-ATPase SPCA1.
Mutations in the ubiquitously expressed secretory-pathway Ca(2+)-ATPase (SPCA1) Ca(2+) pump result in Hailey-Hailey disease, which almost exclusively affects the epidermal part of the skin. We have studied Ca(2+) signaling in human keratinocytes by measuring the free Ca(2+) concentration in the cytoplasm and in the lumen of both the Golgi apparatus and the endoplasmic reticulum. These signals were compared with those recorded in SPCA1-overexpressing and control COS-1 cells. Both the sarco(endo)plasmic-reticulum Ca(2+)-ATPase (SERCA) and SPCA1 can mediate Ca(2+) uptake into the Golgi stacks. Our results indicate that keratinocytes mainly used the SPCA1 Ca(2+) pump to load the Golgi complex with Ca(2+) whereas the SERCA Ca(2+) pump was mainly used in control COS-1 cells. Cytosolic Ca(2+) signals in keratinocytes induced by extracellular ATP or capacitative Ca(2+) entry were characterized by an unusually long latency reflecting extra Ca(2+) buffering by an SPCA1-containing Ca(2+) store, similarly as in SPCA1-overexpressing COS-1 cells. Removal of extracellular Ca(2+) elicited spontaneous cytosolic Ca(2+) transients in keratinocytes, similarly as in SPCA1-overexpressing COS-1 cells. With respect to Ca(2+) signaling keratinocytes and SPCA1-overexpressing COS-1 cells therefore behaved similarly but differed from control COS-1 cells. The relatively large contribution of the SPCA1 pumps for loading the Golgi stores with Ca(2+) in keratinocytes may, at least partially, explain why mutations in the SPCA1 gene preferentially affect the skin in Hailey-Hailey patients.
Callewaert
G
G
Laboratorium voor Fysiologie, K U Leuven Campus Gasthuisberg O/N, Herestraat 49, 3000 Leuven, Belgium.
Parys
J B
JB
De Smedt
H
H
Raeymaekers
L
L
Wuytack
F
F
Vanoevelen
J
J
Van Baelen
K
K
Simoni
A
A
Rizzuto
R
R
Missiaen
L
L
D000818:Animals; D019556:COS Cells; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D000252:Calcium-Transporting ATPases / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism*; D014162:Transfection
C403624:ATP2C1 protein, human; D000252:Calcium-Transporting ATPases; D002118:Calcium