title: Holocarboxylase synthetase is an obligate participant in biotin-mediated regulation of its own expression and of biotin-dependent carboxylases mRNA levels in human cells.
abstract: Holocarboxylase synthetase (HCS) catalyzes the covalent attachment of biotin to five biotin-dependent carboxylases in human cells. Multiple carboxylase deficiency (MCD) is a life-threatening disease characterized by the lack of carboxylase activities because of deficiency of HCS activity. Here, we report the obligatory participation of HCS in the biotin-dependent stimulation of the level of HCS mRNA and those of acetyl-CoA carboxylase and the alpha subunit of propionyl-CoA carboxylase in human cells. Fibroblasts from patients with MCD are unable to increase HCS mRNA in response to biotin unless the vitamin concentration is raised 100-fold, in keeping with mutations that cause a reduced affinity for biotin by the mutant enzyme. The outcome is deficient synthesis of biotinyl-5'-AMP, the active form of the vitamin in the biotinylation reaction. HCS and carboxylase mRNA levels in normal and MCD fibroblasts and HepG2 cells can be restored by the addition of the cGMP analogue, 8-Br-cGMP, and can be abolished by the addition of inhibitors of the soluble form of guanylate cyclase. We propose a regulatory role for biotin in the control of HCS and carboxylase mRNA levels through a signaling cascade that requires HCS, guanylate cyclase, and cGMP-dependent protein kinase.
authors.affiliation: Departamento de Biologia Molecular y Biotecnologia, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, México D.F. 04510, México.
authors.forename: R Sergio
authors.initials: RS
authors.lastname: Solórzano-Vargas
authors.forename: Diana
authors.initials: D
authors.lastname: Pacheco-Alvarez
authors.forename: Alfonso
authors.initials: A
authors.lastname: León-Del-Río
mesh_terms: D001710:Biotin / Q000494:pharmacology*; D019735:Carbon-Carbon Ligases / Q000378:metabolism*; D019731:Carbon-Nitrogen Ligases / Q000737:chemistry* / Q000378:metabolism*; D002460:Cell Line; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000378:metabolism; D017869:Cyclic GMP-Dependent Protein Kinases / Q000378:metabolism; D003609:Dactinomycin / Q000378:metabolism; D003720:Densitometry; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000378:metabolism; D006162:Guanylate Cyclase / Q000378:metabolism; D006801:Humans; D009154:Mutation; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013997:Time Factors; D014815:Vitamins / Q000494:pharmacology
chemical_list: D012333:RNA, Messenger; D014815:Vitamins; D003609:Dactinomycin; C016276:8-bromocyclic GMP; D001710:Biotin; D017869:Cyclic GMP-Dependent Protein Kinases; D006162:Guanylate Cyclase; D019731:Carbon-Nitrogen Ligases; C023312:holocarboxylase synthetases; D019735:Carbon-Carbon Ligases; D006152:Cyclic GMP