XXII. BIOCHEMICKÝ ZJAZD - Jesseniova lekárska fakulta

Posters
54.
IDEBENONE ACTIvaTION OF GLYCEROL-3-PHOSPHATE OXIDATION IN
LIVER MITOCHONDRIA frOM CONTROL AND HYPERTHYROID raTS
Hana Rauchová 1,2 , Martina Vokurková 1,2 and Tomáš Soukup 1
1
Institute of Physiology, Academy of Sciences of the Czech Republic,
2
Centre for Cardiovascular Research, Prague, Czech Republic
A synthetically prepared analog of coenzyme Q (CoQ) with lower hydrophobicity, idebenone
(IDE; hydroxydecyl-ubiquinone), was found to be very effective in animal experiments and
human replacement therapy when the synthesis of CoQ was decreased. In our previous
studies, we found that mitochondrial FAD-linked glycerol-3-phosphate dehydrogenase
(GPDH; EC 1.1.99.5) from brown adipose tissue is activated by IDE. However, in most
mammalian tissues expression of GPDH is highly depressed and enzyme activity is very
low. Thyroid hormones are known to have a marked influence on GPDH activity; they
especially induce GPDH activity in liver. The aim of our study was to test to what extent
IDE can activate glycerol phosphate (GP) oxidation measured as oxygen uptake and GP
cytochrome c oxidoreductase activity in mitochondria from control and hyperthyroid rat
liver. We found the significant increase of GP-dependent oxygen uptake as well as the
activation of enzyme activity. Our results indicate that IDE may be used for the activation
of the GP shuttle catalyzing the interconversion between dihydroxyaceton phosphate and
GP (formed by GPDH together with its cytosolic NADH-dependent counterpart) through
which NADH from cytosol can be oxidized by the mitochondrial respiratory chain to contribute
to the maintenance of the high rate of glycolysis. It might be important in the case
when mitochondrial Complex I is impaired and energy production must be maintained.
Acknowledgement: This work was supported by the GACR (303/09/0570) and Ministry
of Education, Youth and Sport (1M6798582302 and AV0Z 50110509).
174 XXII. Biochemistry Congress, Martin