6533b7cffe1ef96bd125869c
RESEARCH PRODUCT
Characterization of a mutant form of human apolipoprotein B (Thr26_Tyr27del) associated with familial hypobetalipoproteinemia
Maurizio AvernaDavide NotoLucia MagnoloZemin YaoPatrizia TarugiSebastiano CalandraAngelo B. Cefalùsubject
0301 basic medicineSettore MED/09 - Medicina InternaTime FactorsApolipoprotein B-48 secretionApolipoprotein BMutantDNA Mutational AnalysisApolipoprotein B mutation Apolipoprotein B-48 secretion Hypobetalipoproteinemia Proteasomal degradation030204 cardiovascular system & hematologymedicine.disease_causeEndoplasmic ReticulumHypobetalipoproteinemiaschemistry.chemical_compound0302 clinical medicineProteasomal degradationProteolysiSequence DeletionMutationbiologyMedicine (all)TransfectionProteasome InhibitorPhenotypeBiochemistryApolipoprotein B-100lipids (amino acids peptides and proteins)Proteasome InhibitorsHumanHeterozygoteProteasome Endopeptidase ComplexTime FactorCycloheximideTransfectiondigestive systemCell LineDNA Mutational Analysi03 medical and health sciencesmedicineHumansSecretionGenetic Predisposition to DiseaseMolecular BiologyEndoplasmic reticulumnutritional and metabolic diseasesCell Biologymedicine.diseaseMolecular biology030104 developmental biologychemistryProteolysisbiology.proteinHypobetalipoproteinemiaApolipoprotein B mutationApolipoprotein B-48Hypobetalipoproteinemiadescription
We have previously identified a deletion mutant of human apoB [apoB (Thr26_Tyr27del)] in a subject with primary hypobetalipoproteinemia. The present study determined the effect of Thr26_Tyr27del mutation on apoB secretion using transfected McA-RH7777 cells. Transient or stable transfection of apoB-48 containing the Thr26_Tyr27del mutation showed drastically reduced secretion of the mutant as compared to wild-type apoB-48. No lipoproteins containing the mutant apoB-48 were secreted into the medium. Incubation of transfected cells in a lipid-rich medium in the presence of cycloheximide showed rapid turnover of cell-associated mutant apoB-48 as compared to that of wild-type apoB-48. Immunofluorescence experiments showed that the mutant apoB-48 was mostly localized in the endoplasmic reticulum. Treatment with the proteasomal inhibitor MG132 markedly attenuated the turnover of cell-associated mutant apoB-48, whereas treatment with inhibitors of autophagosomal/lysosomal function (e.g. 3-MA or ammonium chloride) had no effect. Taken together, these results indicated that the defective secretion of the Thr26_Tyr27del mutant was associated with increased intracellular degradation of apoB through the proteasome-dependent pathway.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2016-01-01 |