Effects of targeted suppression of glutaryl-CoA dehydrogenase by lentivirus-mediated shRNA and excessive intake of lysine on apoptosis in rat striatal neurons

PLoS One. 2013 May 2;8(5):e63084. doi: 10.1371/journal.pone.0063084. Print 2013.

Abstract

In glutaric aciduria type 1 (GA1), glutaryl-CoA dehydrogenase (GCDH) deficiency has been shown to be responsible for the accumulation of glutaric acid and striatal degeneration. However, the mechanisms by which GA1 induces striatal degeneration remain unclear. In this study, we aimed to establish a novel neuronal model of GA1 and to investigate the effects of GCDH deficiency and lysine-related metabolites on the viability of rat striatal neurons. Thus we constructed a lentiviral vector containing short hairpin RNA targeted against the GCDH gene expression (lentivirus-shRNA) in neurons. A virus containing a scrambled short hairpin RNA construct served as a control. Addition of lysine (5 mmol/L) was used to mimic hypermetabolism. Cell viability was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. Apoptosis was assessed using Hoechst33342 staining and Annexin V-PE/7-AAD staining. The mitochondrial membrane potential (MPP) was monitored using tetramethylrhodamine methyl ester. The expression levels of caspases 3, 8, and 9 were determined by Western blotting. We found that lentivirus-shRNA induced apoptosis and decreased MMP levels in neurons, and addition of 5 mmol/L lysine enhanced this effect markedly. Lentivirus-shRNA upregulated the protein levels of caspases 3 and 9 regardless of the presence of 5 mmol/L lysine. The expression level of caspase 8 was higher in neurons co-treated with lentivirus-shRNA and 5 mmol/L lysine than in control. Benzyloxy-carbonyl-Val-Ala-Asp(OMe)-fluoromethylketone, a pan-caspase inhibitor, blocked the apoptosis induced by lentivirus-shRNA and 5 mmol/L lysine to a great extent. These results indicate that the targeted suppression of GCDH by lentivirus-mediated shRNA and excessive intake of lysine may be a useful cell model of GA1. These also suggest that GA1-induced striatal degeneration is partially caspase-dependent.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Metabolism, Inborn Errors / enzymology
  • Amino Acid Metabolism, Inborn Errors / metabolism
  • Amino Acid Metabolism, Inborn Errors / pathology
  • Animals
  • Apoptosis / drug effects
  • Apoptosis / genetics*
  • Base Sequence
  • Biological Transport / genetics
  • Brain Diseases, Metabolic / enzymology
  • Brain Diseases, Metabolic / metabolism
  • Brain Diseases, Metabolic / pathology
  • Caspase Inhibitors / pharmacology
  • Cell Survival / drug effects
  • Cell Survival / genetics
  • Gene Expression Regulation / drug effects
  • Gene Expression Regulation / genetics
  • Gene Knockdown Techniques*
  • Glutaryl-CoA Dehydrogenase / deficiency
  • Glutaryl-CoA Dehydrogenase / genetics*
  • Glutaryl-CoA Dehydrogenase / metabolism
  • Lentivirus / genetics*
  • Lysine / metabolism
  • Lysine / pharmacology*
  • Membrane Potential, Mitochondrial / drug effects
  • Membrane Potential, Mitochondrial / genetics
  • Neostriatum / cytology
  • Neurons / cytology*
  • Neurons / drug effects
  • Neurons / metabolism
  • RNA, Small Interfering* / genetics
  • Rats
  • Rats, Sprague-Dawley

Substances

  • Caspase Inhibitors
  • RNA, Small Interfering
  • Glutaryl-CoA Dehydrogenase
  • Lysine

Supplementary concepts

  • Glutaric Acidemia I

Grants and funding

This study is supported by the National Natural Science Foundation of China (No.81070699) [X.L.], Twelfth Five-year National Science Supported Planning Project (No.2012BAI09B04) [X.L.], the Sector Fund from the Ministry of Health of China (No. 201002006) [X.L.], and Innovation Team Development Plan of the Ministry of Education of China (No. IRT1131) [Q.N.]. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.