title: Apolipoprotein B mRNA editing and the reduction in synthesis and secretion of the atherogenic risk factor, apolipoprotein B100 can be effectively targeted through TAT-mediated protein transduction.
abstract: Hepatic very-low-density lipoprotein particles (VLDL) containing full-length apolipoprotein B100 are metabolized in the blood stream to low-density lipoprotein (LDL) particles, whose elevated levels increase the risk of atherosclerosis. Statins and bile-acid sequestrants are effective LDL-lowering therapies for many patients. Development of alternative therapies remains important for patients with adverse reactions to conventional therapy, with defects in the LDL receptor-dependent lipoprotein uptake pathway and for intervention in children. Editing of apoB mRNA by the enzyme APOBEC-1 changes a glutamine codon to a stop codon, leading to the synthesis and secretion of apoB48-containing VLDL, which are rapidly cleared before they can be metabolized to LDL. Human liver does not edit apoB mRNA because it does not express APOBEC-1. Although initially promising, enthusiasm for apobec-1 gene therapy for hypercholesterolemia was blunted by the finding that uncontrolled transgenic expression of APOBEC-1 led to nonspecific editing of mRNAs and pathology. We demonstrate that APOBEC-1 fused to TAT entered primary hepatocytes, where it induced a transient increase in mRNA editing activity and enhanced synthesis and secretion of VLDL containing apoB48. Protein transduction of APOBEC-1 transiently stimulated high levels of apoB mRNA editing in a dose-dependent manner without loss of fidelity. These results suggested that apoB mRNA editing should be re-evaluated as a LDL-lowering therapeutic target in the new context of protein transduction therapy.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA.
authors.forename: Yan
authors.initials: Y
authors.lastname: Yang
authors.forename: Nazzareno
authors.initials: N
authors.lastname: Ballatori
authors.forename: Harold C
authors.initials: HC
authors.lastname: Smith
mesh_terms: D000071479:APOBEC-1 Deaminase; D000818:Animals; D053299:Apolipoprotein B-100; D001055:Apolipoproteins B / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D003564:Cytidine Deaminase; D015696:Gene Products, tat / Q000235:genetics / Q000494:pharmacology*; D022781:Hepatocytes / Q000187:drug effects* / Q000502:physiology; D008074:Lipoproteins / Q000378:metabolism; D008297:Male; D017393:RNA Editing / Q000187:drug effects*; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011993:Recombinant Fusion Proteins / Q000494:pharmacology; D012307:Risk Factors
chemical_list: D053299:Apolipoprotein B-100; D001055:Apolipoproteins B; D015696:Gene Products, tat; D008074:Lipoproteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D000071479:APOBEC-1 Deaminase; C000605089:APOBEC1 protein, human; C000605091:Apobec1 protein, rat; D003564:Cytidine Deaminase