UV-A light regulation of arylalkylamine N-acetyltransferase activity in the chick pineal gland: role of cAMP and proteasomal proteolysis.
Acute exposure of dark-adapted, cultured chick pineal glands to UV-A light significantly decreased the tissue cAMP concentration and the activity of arylalkylamine N-acetyltransferase (AANAT), the penultimate and key regulatory enzyme in the melatonin biosynthetic pathway. The magnitude of these changes was dependent on the duration of UV-A exposure. The UV-A light-evoked decline in pineal AANAT activity was blocked by cAMP protagonists (forskolin and dibutyryl-cAMP) and by inhibitors of the proteasomal degradation pathway (MG-132, proteasome inhibitor I, and lactacystin). These results indicate that the chick pineal gland is directly sensitive to UV-A light. By analogy to white light, the suppressive action of UV-A radiation on AANAT activity in the chick pineal gland involves changes in the tissue cAMP level and enhanced proteasomal proteolysis.
Rosiak
Jolanta
J
Centre for Medical Biology, Polish Academy of Sciences, Łòdź, Poland.
Michael Iuvone
P
P
Zawilska
Jolanta B
JB
D000111:Acetylcysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D047068:Arylalkylamine N-Acetyltransferase / Q000378:metabolism*; D003994:Bucladesine / Q000494:pharmacology; D002645:Chickens; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000502:physiology*; D003623:Dark Adaptation; D007976:Leupeptins / Q000494:pharmacology; D008297:Male; D009842:Oligopeptides / Q000494:pharmacology; D009924:Organ Culture Techniques; D010870:Pineal Gland / Q000502:physiology* / Q000528:radiation effects*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D013997:Time Factors; D014466:Ultraviolet Rays
D007976:Leupeptins; D009842:Oligopeptides; C090535:benzyloxycarbonyl-isoleucyl-glutamyl(O-tert-butyl)-alanyl-leucinal; C067713:lactacystin; D005576:Colforsin; D003994:Bucladesine; D000242:Cyclic AMP; D047068:Arylalkylamine N-Acetyltransferase; D046988:Proteasome Endopeptidase Complex; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde; D000111:Acetylcysteine