Adenylate cyclase induces intracellular calcium increase in single human epidermal keratinocytes measured by fluorescence microscopy using Fura 2-AM.
Intracellular calcium ([Ca2+]i) is an important second messenger of extracellular signals to induce various cellular responses. Extracellular and intracellular Ca2+ are considered to be important for cellular differentiation and proliferation of epidermal keratinocytes. Several mechanisms which increase [Ca2+]i have been demonstrated in various tissues, but in epidermal keratinocytes these mechanisms are poorly understood. In epidermal keratinocytes the adenylate cyclase-cyclic AMP response is thought to regulate cell proliferation and differentiation. However, the series of reactions which follow the cyclic AMP response remain unknown. Beta-adrenergic agonists increase [Ca2+]i in cultured epidermal keratinocytes, and we have therefore studied whether stimulation of keratinocyte adenylate cyclase could induce [Ca2+]i increase, by using fluorescence microscopy with Fura 2-AM. Adenosine and histamine, which are known to be keratinocyte adenylate cyclase receptor agonists, induced transient [Ca2+]i increase, as did epinephrine. In addition, forskolin, a direct adenylate cyclase activator, and dibutyryl-cyclic AMP also induced an increase in [Ca2+]i. In a calcium-free medium epinephrine, adenosine, histamine and dibutyryl-cyclic AMP induced an increase in [Ca2+]i. These results suggest that cyclic AMP in human epidermal keratinocytes regulates [Ca2+]i, which is released from intracellular stores.
Yasui
C
C
Department of Dermatology, Hokkaido University School of Medicine, Sapporo, Japan.
Koizumi
H
H
Fukaya
T
T
Kumakiri
M
M
Ohkawara
A
A
Ueda
T
T
D000241:Adenosine / Q000494:pharmacology; D000262:Adenylyl Cyclases / Q000378:metabolism*; D003994:Bucladesine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D005456:Fluorescent Dyes; D016257:Fura-2 / Q000031:analogs & derivatives; D006632:Histamine / Q000494:pharmacology; D006801:Humans; D007424:Intracellular Fluid / Q000378:metabolism*; D015603:Keratinocytes / Q000378:metabolism*; D008856:Microscopy, Fluorescence
D005456:Fluorescent Dyes; C049925:fura-2-am; D005576:Colforsin; D003994:Bucladesine; D006632:Histamine; D000262:Adenylyl Cyclases; D000241:Adenosine; D002118:Calcium; D016257:Fura-2; D004837:Epinephrine