Molecular basis of inborn errors of ketone body metabolism : mainly basic studies for responsible genes

点击翻译按钮获取中文摘要

1.Succinyl-CoA:3-ketoacid CoA transferase (SCOT) deficiency1)We revealed and proved that SCOT deficient patients with "mild" mutations did not always show permanent ketosis which is pathognomonic feature of SCOT deficiency.2)In a SCOT deficient patient, we found exons 6 and 7 skipping, which was caused by G>A substitution at the end nucleotide of exon 6. We analyzed heteronuclear RNA and cytosolic RNA and revealed that mRNA with single exon 6 skipping was degraded rapidly by nonsense-mediated RNA decay. Since mRNA with exon 6 and 7 skipping was in frame and although it was minor transcript in nuclear RNA, this mRNA became a major product in cytosolic fraction.2.Mitochondrial acetyoacetyl-CoA thiolase (T2) deficiency1)A coupled assay with tiglyl-CoA had been widely used for the enzymatic diagnosis of T2 deficiency in Europe and USA. We revealed and proved that the result of coupled assay using tiglyl-CoA was normal in two T2 deficient patients with "mild" mutations. This means that T2 deficient patients with "mild" mutations had been mis-diagnosed as normal using the coupled assay with tiglyl-CoA.2)We identified a large T2 gene deletion including exons 2-4 caused by unequal homologous recombination. This is the first mutation caused by this mechanism in T2 gene.3.Liver specific suppression of human SCOT gene expression.We analyzed status of methylation in CpG islands around SCOT gene promotor regions in HeLa cells and hepatoblastoma cell lines and murine hepatic tissues and cardiac muscle. Unexpectedly, the CpG islands around SCOT promotor regions were hypomethylated in even hepatoblastoma cell lines and murine hepatic tissues where SCOT gene was almost completely suppressed.4.Tertiary structure of human thiolase family.We determined a crystal tertiary structure of cytosolic acetoacetyl-CoA thiolase and found several new findings in enzyme mechamism using the structure.