A Drosophila model for primary coenzyme Q deficiency and dietary rescue in the developing nervous system

Abstract

SUMMARYCoenzyme Q (CoQ) or ubiquinone is a lipid component of the electron transport chain required for ATP generation in mitochondria. Mutations in CoQ biosynthetic genes are associated with rare but severe infantile multisystemic diseases. CoQ itself is a popular over-the-counter dietary supplement that some clinical and rodent studies suggest might be beneficial for neurodegenerative diseases. Here, we identify mutations in the Drosophila qless gene, which encodes an orthologue of the human PDSS1 prenyl transferase that synthesizes the isoprenoid side chain of CoQ. We show that neurons lacking qless activity upregulate markers of mitochondrial stress and undergo caspase-dependent apoptosis. Surprisingly, even though experimental inhibition of caspase activity did not prevent mitochondrial disruption, it was sufficient to rescue the size of neural progenitor clones. This demonstrates that, within the developing larval CNS, qless activity is required primarily for cell survival rather than for cell growth and proliferation. Full rescue of the qless neural phenotype was achieved by dietary supplementation with CoQ4, CoQ9 or CoQ10, indicating that a side chain as short as four isoprenoid units can provide in vivo activity. Together, these findings show that Drosophila qless provides a useful model for studying the neural effects of CoQ deficiency and dietary supplementation.A Drosophila model for primary coenzyme Q deficiency and dietary rescue in the developing nervous system mutations, 109 and 264, were isolated in a mosaic screen for genes regulating the size of neural progenitor (neuroblast) clones in the larval Drosophila CNS. Both mutations are embryonic-lethal, and were mapped on the right arm of chromosome 3 by failure to complement molecularly defined deficiencies and a lethal EP element inserted into a previously uncharacterized gene, CG31005 ( Fig. 1A; supplementary material Fig. S1A). The predicted protein product of CG31005 (AAF57135) matches that encoded by human PDSS1 (AAH49211) with a BLASTP E-value of 2ϫ10 -102 . On this basis, and in light of later CoQ rescue studies, we subsequently refer to the CG31005 gene as qless. Sequencing revealed that the qless 109 mutation is a G to A swap at position 1354 of the predicted transcript (CG31005-RA), corresponding to a S215N mutation in the predicted Qless protein (CG31005-PA) ( Fig. 1A; supplementary material Fig. S1B). S215 is located ten amino acids C-terminal to the first of the two predicted aspartate-rich DDxxD sites that mediate substrate binding and catalysis by prenyl transferases (Song and Poulter, 1994). Alignments of PDSS1-related prenyl transferases in a wide variety of different organisms shows that position 215 is highly conserved, with either a serine or threonine occupying this position (Fig. 1B). A protein structural model of the region around the first DDxxD motif predicts that the S215N mutation disrupts hydrogen bonding of residue 215 to the N217 side chain, instead resulting in inappropriate hydrogen bonding to Y148 in the N-terminus...

Cellular factories for coenzyme Q10 production

“…In Caenorhabditis elegans , CoQ deficiency leads to GABA neuron degeneration, and in Drosophila melanogaster , it can cause mitochondrial stress and neuronal apoptosis [16, 17]. In humans, CoQ 10 deficiency has been implicated in various diseases involving muscle and neural development, with the severity of the disease correlated with the acuteness of the CoQ 10 shortfall [18].…”

Alternative Synthesis of 2-(4-Benzoyl-Piperazin-1-Ylmethyl)-5, 6-Dimethoxy-3-Methyl-[1, 4]Benzoquinone

“…3 Phenyl- [4-(2, 3, 4, 5-tetramethoxy-6-methyl-benzyl)-piperazin-1-yl]methanone (4): 9 Compound 2 (2.6g, 10mmol), N-benzoylpiperazine 3 (1.9 g, 10 mmol), and K 2 CO 3 ( 2.1g, 15 mmol) in DMF (20 mL) were heated at 80 °C for 4 h , After completion of the reaction, water (50 mL) was added and the resulting mixture was extracted with three portions of CH 2 Cl 2 (20 mL). The combined extracts were washed with brine until neutrality, then dried over anhydrous Na 2 2-Chloromethyl-5, 6-dimethoxy-3-methyl- [1,4]benzoquinone (5): 2 Excess CAN (8.2g, 15 mmol) in water (9 mL) was added dropwise at 0 °C to a solution of compound 2 (1.3 g, 5 mmol) in THF (6 mL). The mixture was stirred at room temperature for 2 h. The progress of the reaction was monitored by thin-layer-chromatography (TLC).…”

“…The orange extracts were washed with brine until neutrality, then dried over anhydrous Na 2 SO 4 and concentrated in vacuo. The crude products were purified by a silica-gel column chromatography with petroleum ether and EtOAc (8:1) as eluent to give the desired benzoquinone 2-(4-Benzoyl-piperazin-1-ylmethyl)-5, 6-dimethoxy-3-methyl- [1,4] benzoquinone (6): 5 Benzoquinone 5 (0.30 g, 1.3 mmol), N-benzoylpiperazine 3 (0.27 g, 1.4 mmol) , and K 2 CO 3 (0.28 g, 2.0 mmol) in CH 2 Cl 2 were heated at 40 °C for 2 h , After completion of the reaction, the crude was extracted with three portions of CH 2 Cl 2 (10 mL). The orange extracts were washed with brine until neutrality, then dried over anhydrous Na 2 SO 4 and concentrated in vacuo.…”

Invertebrate Models for Coenzyme Q₁₀ Deficiency

“…Neurons lacking qless upregulate markers of mitochondrial stress and undergo caspase-dependent apoptosis [Grant et al, 2010]. Dietary supplementation with CoQ 10 rescued the neural phenotype of qless mutants.…”