Molecular mechanism of familial hypertriglyceridemia caused by lipoprotein lipase gene mutation (C310R/E396V) / 中华内分泌代谢杂志

ABSTRACT

Objective The purpose of this study is to investigate the molecular mechanisms of p.C310R(c.T928C) and p.E396V(c.A1187T) lipoprotein lipase(LPL) gene mutations in vitro, which may help to construct the spectrum of LPL gene mutations and phenotype. It also can provide accurate early diagnosis for high-risk population of familial hypertriglyceridemia and provide the basis for the development of gene targeted therapy. Methods Genomic DNA was extracted from proband′s family members′ peripheral blood cells and screened by whole-exome sequencing to verify candidate gene variations. PCR products were afterwards directly sequenced again to confirm corresponding LPL variants. At the cellular level, lentiviruses containing LPL mutations were constructed and then transfected into COS-1 cells. Functional significance of the mutants was corroborated by analyzing LPL activity and mass in the cell medium and lysates via ELISA and enzyme-fluorescent method. mRNA was assayed by RT-PCR to confirm the effect on gene transcription. Results DNA sequence analysis revealed that the proband was a heterozygote for a novel c.T928C mutation in exon 6 of LPL gene, while his nephew was a compound heterozygote for the c.T928C mutation in exon 6 and a novel c.A1187T mutation in exon 8. In vitro studies, these two mutations can cause decreased activity and mass of extracellular LPL(P<0.05). Moreover, further investigation indicated that LPL C310R mutation tremendously affected post-transcriptional modification of LPL gene, whereas LPL E396V mutation dampened intracellular LPL trafficking. Conclusion Both the mutations are pathogenic by reducing the activity and mass of LPL in the plasma, which affected normal metabolism of triglycerides.