Alpha-parvalbumin reduces depolarization-induced elevations of cytosolic free calcium in human neuroblastoma cells.
We investigated whether the expression of human alpha-parvalbumin affects depolarization-induced elevations of the cytosolic free calcium concentration ([Ca2+]i) in human neuroblastoma SKNBE2 cells. A full length human parvalbumin cDNA was cloned by PCR from human cerebellum and transiently transfected into SKNBE2 cells. Immunofluorescence staining using an antibody raised against parvalbumin revealed a transfection efficacy of about 14%. In parvalbumin-expressing SKNBE2 cells, parvalbumin concentration determined by quantitative Western blotting amounted to 0.42 mM. Transfected SKNBE2 cells were depolarized for 2 min by 50 mM K+. During this period, [Ca2+]i was monitored by video microfluorimetry using the Ca2+ indicator Fura-2. In a fraction of cells, depolarization induced a transient elevation in [Ca2+]i. The size of this elevation was compared with the immunofluorimetrically determined expression of parvalbumin on a cell-to-cell basis. Cells with a significant parvalbumin immunofluorescence responded to depolarization with smaller elevations in [Ca2+]i than non-parvalbumin-expressing cells. Resting [Ca2+]i did not differ between parvalbumin-expressing and control cells. These observations indicate that large depolarization-induced transient elevations of [Ca2+]i in neuroblastoma cells can be suppressed by parvalbumin.
Dreessen
J
J
Department of Molecular and Cellular Neurobiology, CNS Research, Ciba, Basel, Switzerland.
Lutum
C
C
Schäfer
B W
BW
Heizmann
C W
CW
Knöpfel
T
T
D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D003001:Cloning, Molecular; D003600:Cytosol / Q000378:metabolism; D017931:DNA Primers / Q000737:chemistry; D004274:DNA, Recombinant / Q000235:genetics; D019084:Fluorescent Antibody Technique, Indirect; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D006041:Goats / Q000276:immunology; D006801:Humans; D018715:Microscopy, Video; D008969:Molecular Sequence Data; D009447:Neuroblastoma / Q000235:genetics / Q000378:metabolism*; D010320:Parvalbumins / Q000032:analysis / Q000235:genetics* / Q000276:immunology; D016133:Polymerase Chain Reaction; D011188:Potassium / Q000494:pharmacology; D011817:Rabbits; D051381:Rats; D014162:Transfection / Q000235:genetics*; D014407:Tumor Cells, Cultured
D017931:DNA Primers; D004274:DNA, Recombinant; D010320:Parvalbumins; D011188:Potassium; D002118:Calcium