Investigation of coenzyme Q biosynthesis in human fibroblast and HepG2 cells.
Coenzyme Q (CoQ) deficiency occurs in genetic disorders, during aging and various diseases. Diagnosis requires skin fibroblasts in tissue culture. [3H]Mevalonate incorporation was appropriate to measure the rate of CoQ synthesis in fibroblasts and hepatoblastoma cells. [14C]p-Hydroxybenzoate had limited permeability, but it could be increased with Fugene and cyclodextrin. Inhibition of decaprenyl-4-hydroxybenzoate transferase results in the accumulation of decaprenyl diphosphate, an indicator of enzyme deficiency. Also, analysis of the corresponding mRNAs in this case is useful. In vitro assays to measure trans-prenyltransferase and decaprenyl-4-hydroxybenzoate transferase activities are not available. Neither measurement of methyltransferases is reliable in human cells. In vitro reconstruction of CoQ synthesis, in opposite to cholesterol synthesis, proved to be unsuccessful. Thus, the biochemical characterization of the CoQ biosynthetic system in human cells is restricted to a few reliable analytical procedures.
Tekle
Michael
M
Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden. michael.tekle@dbb.su.se
Turunen
Mikael
M
Dallner
Gustav
G
Chojnacki
Tadeusz
T
Swiezewska
Ewa
E
D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D005347:Fibroblasts; D006801:Humans; D008099:Liver / Q000378:metabolism; D008745:Methylation; D008798:Mevalonic Acid / Q000378:metabolism; D010226:Parabens / Q000378:metabolism; D011106:Polyisoprenyl Phosphates; D012333:RNA, Messenger / Q000235:genetics; D014451:Ubiquinone / Q000032:analysis* / Q000096:biosynthesis*
D010226:Parabens; D011106:Polyisoprenyl Phosphates; D012333:RNA, Messenger; D014451:Ubiquinone; C068697:decaprenyl phosphate; D008798:Mevalonic Acid