Affiliations: Department of Biochemistry and Biophysics, Stockholm
University, 106 91 Stockholm, Sweden | Department of Molecular Medicine, Karolinska Hospital,
171 76 Stockholm, Sweden | Institute of Biochemistry and Biophysics, Polish
Academy of Sciences, 02-532 Warsaw, Poland
Abstract: All animal cells synthesize sufficient amounts of coenzyme Q (CoQ)
and the cells also possess the capacity to metabolize the lipid. The main
product of the metabolism is an intact ring with a short carboxylated side
chain which glucuronidated in the liver and excreted mainly into the bile
(Nakamura et al., Biofactors 9 (1999), 111–119). In other cells
CoQ is phosphorylated, transferred into the blood and excreted through the
urine. The biosynthesis of this lipid is regulated by nuclear receptors.
PPARα is not required for the biosynthesis, or
induction upon cold exposure, but it is necessary for the elevated CoQ
synthesis during peroxisomal induction. RXRα is
involved in the basal synthesis of CoQ and also in the increased synthesis upon
cold treatment but is not required for peroxisomal induction. Dietary CoQ in
human appear in the blood and it is taken up by mononuclear but not polynuclear
cells. The former cells display a specific phospholipid modification, an
increase of arachidonic acid content. In monocytes the CoQ administration leads
to a significant decrease of the β2-integrin CD11b and
the complement receptor CD35. CD11b is one of the adhesion factors regulating
the entry of these cells into the arterial wall which demonstrates that the
anti-atherogenic effect of CoQ is mediated by other mechanisms beside its
antioxidant protection.
