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Functional characterization of human COQ4, a gene required for Coenzyme Q10 biosynthesis.

ABSTRACT: Defects in genes involved in coenzyme Q (CoQ) biosynthesis cause primary CoQ deficiency, a severe multisystem disorders presenting as progressive encephalomyopathy and nephropathy. The COQ4 gene encodes an essential factor for biosynthesis in Saccharomyces cerevisiae. We have identified and cloned its human ortholog, COQ4, which is located on chromosome 9q34.13, and is transcribed into a 795 base-pair open reading frame, encoding a 265 amino acid (aa) protein (Isoform 1) with a predicted N-terminal mitochondrial targeting sequence. It shares 39% identity and 55% similarity with the yeast protein. Coq4 protein has no known enzymatic function, but may be a core component of multisubunit complex required for CoQ biosynthesis. The human transcript is detected in Northern blots as a approximately 1.4 kb single band and is expressed ubiquitously, but at high levels in liver, lung, and pancreas. Transcription initiates at multiple sites, located 333-23 nucleotides upstream of the ATG. A second group of transcripts originating inside intron 1 of the gene encodes a 241 aa protein, which lacks the mitochondrial targeting sequence (isoform 2). Expression of GFP-fusion proteins in HeLa cells confirmed that only isoform 1 is targeted to mitochondria. The functional significance of the second isoform is unknown. Human COQ4 isoform 1, expressed from a multicopy plasmid, efficiently restores both growth in glycerol, and CoQ content in COQ4(null) yeast strains. Human COQ4 is an interesting candidate gene for patients with isolated CoQ(10) deficiency.

SUBMITTER: Casarin A

PROVIDER: S-EPMC4345104 | biostudies-literature | 2008 Jul

REPOSITORIES: biostudies-literature

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Functional characterization of human COQ4, a gene required for Coenzyme Q10 biosynthesis.

Casarin Alberto A Jimenez-Ortega Jose Carlos JC Trevisson Eva E Pertegato Vanessa V Doimo Mara M Ferrero-Gomez Maria Lara ML Abbadi Sara S Artuch Rafael R Quinzii Catarina C Hirano Michio M Basso Giuseppe G Ocaña Carlos Santos CS Navas Placido P Salviati Leonardo L

Biochemical and biophysical research communications 20080512 1

Defects in genes involved in coenzyme Q (CoQ) biosynthesis cause primary CoQ deficiency, a severe multisystem disorders presenting as progressive encephalomyopathy and nephropathy. The COQ4 gene encodes an essential factor for biosynthesis in Saccharomyces cerevisiae. We have identified and cloned its human ortholog, COQ4, which is located on chromosome 9q34.13, and is transcribed into a 795 base-pair open reading frame, encoding a 265 amino acid (aa) protein (Isoform 1) with a predicted N-termi ...[more]

PMID: 18474229

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Project description:Our present study reveals significant decelerating effects on senescence processes in middle-aged SAMP1 mice supplemented for 6 or 14 months with the reduced form (QH2, 500 mg/ kg BW/ day) of coenzyme Q10 (CoQ10). To unravel molecular mechanisms of these CoQ10 effects, a genome-wide transcript profiling in liver, heart, brain and kidney of SAMP1 mice supplemented with the reduced (QH2) or oxidized form of CoQ10 (Q10) was performed. Liver seems to be the main target tissue of CoQ10 intervention, followed by kidney, heart and brain. Stringent evaluation of the resulting data revealed that QH2 has a stronger impact on gene expression than Q10, which was primarily due to differences in the bioavailability. Indeed, we found that QH2 supplementation was more effective than Q10 to increase levels of CoQ10 in the liver of SAMP1 mice (54.92-fold and 30.36-fold, respectively). To identify functional and regulatory connections of the âtop 50â (p < 0.05) up- and down-regulated QH2-sensitive transcripts in liver (fold changes ranging from 21.24 to -6.12), text mining analysis (Genomatix BiblioSphere, GFG level B3) was used. Hereby, we identified 11 QH2-sensitive genes which are regulated by PPAR-Î± and are primarily involved in cholesterol synthesis (e.g. HMGCS1, HMGCL, HMGCR), fat assimilation (FABP5), lipoprotein metabolism (PLTP) and inflammation (STAT-1). Thus, we provide evidence that QH2 is involved in the reduction of fat and cholesterol synthesis via modulation of the PPAR-Î± signalling pathway. These data may explain, at least in part, the observed effects on decelerated age-dependent degeneration processes in QH2-supplemented SAMP1 mice. Whole genome expression profiles were analysed from liver, heart, brain and kidney (each analyzed separately) of SAMP1 mice supplemented with QH2, Q10 or a control diet. From every experimental group, three mice each were sacrificed 6 or 14 months after supplementation, resulting in a total of 72 microarrays.

Dataset Information

Functional characterization of human COQ4, a gene required for Coenzyme Q10 biosynthesis.

Publications

Functional characterization of human COQ4, a gene required for Coenzyme Q10 biosynthesis.

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