Inhibition of diphosphatidylglycerol synthesis by u.v. A radiations in N.C.T.C. 2544 human keratinocytes.
The effects of u.v. A radiations on phospholipid synthesis were studied in the N.C.T.C. 2544 human keratinocyte cell line, by using [14C]arachidonic acid, [14C]oleic acid or sodium [32P]orthophosphate as precursors. Cells were irradiated in Hanks' medium with 365 nm light at doses up to 19 J/cm2, and then phospholipid synthesis from the three precursors was studied. Under these conditions, only small alterations in the incorporation pattern of [14C]arachidonic into phospholipids [phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylinositol (PI)] were observed, for u.v. A irradiation doses up to 19 J/cm2. In contrast, with [14C]oleic acid as precursor, two additional spots were observed, which co-migrate with pure phosphatidylglycerol (PG) and diphosphatidylglycerol (DPG) standards. The incorporation of [14C]oleic acid into PG and DPG was decreased in a dose-dependent manner after u.v. A exposure, with about 50% and 75% decreases at 9.5 J/cm2 and 19 J/cm2 respectively. As for arachidonic acid incorporation, no significant differences in the synthesis of the major phospholipids (PC, PE, PI) were noted upon u.v. A exposure. The dramatic and selective decrease in PG and DPG syntheses was confirmed with [32P]orthophosphate as precursor. As DPG is a specific component of the mitochondrial inner membrane, it appears that one of the early kinds of damage induced by u.v. A irradiation could be the impairment of mitochondrial functions.
Djavaheri-Mergny
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M
Laboratoire de Physico-Chimie de l'Adaptation Biologique, INSERM U312, Muséum National d'Histoire Naturelle de Paris, France.
Mora
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L
Mazière
C
C
Auclair
M
M
Santus
R
R
Dubertret
L
L
Mazière
J C
JC
D002308:Cardiolipins / Q000096:biosynthesis*; D002460:Cell Line; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism / Q000528:radiation effects*; D007700:Kinetics; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D014466:Ultraviolet Rays
D002308:Cardiolipins; D017392:Thiobarbituric Acid Reactive Substances