Identification and Characterisation of a Novel Pathogenic Mutation in the Human Lipodystrophy Gene AGPAT2 : C48R: A Novel Mutation in AGPAT2.
Identification and Characterisation of a Novel Pathogenic Mutation in the Human Lipodystrophy Gene AGPAT2 : C48R: A Novel Mutation in AGPAT2.
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DOI：
10.1007/8904_2012_181
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
Rochford, J J
中科院分区：
文献类型：
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作者：
Ramanathan, N;Ahmed, M;Raffan, E;Stewart, C L;O'Rahilly, S;Semple, R K;Raef, H;Rochford, J J
编码1-酰基甘油-3-磷酸-O-酰基转移酶2（AGPAT 2）的AGPAT 2中的功能缺失突变产生先天性全身性脂肪营养不良（CGL）。我们在两个患有假性肢端肥大症、糖尿病和严重血脂异常的兄弟姐妹中筛选了AGPAT 2基因，并确定了AGPAT 2中一个新的突变，该突变导致了一个单一的氨基酸取代，p.Cys48Arg。我们随后研究了这种突变和先前报道的p.Leu228Pro突变与临床疾病的分子致病机制。野生型和突变体AGPAT 2在对照和AGPAT 2缺陷的前脂肪细胞系中表达。测定mRNA和蛋白质表达，并评估每种AGPAT 2种类在AGPAT 2缺陷细胞中拯救脂肪细胞分化的能力。与野生型AGPAT 2相比，p.Cys48Arg和p.Leu228Pro AGPAT 2的蛋白水平显著降低，尽管mRNA水平相当。野生型AGPAT 2的稳定表达部分挽救了AGPAT 2缺陷前脂肪细胞中的脂肪形成，而p.Cys48Arg或p.Leu228Pro AGPAT 2的稳定表达则没有。总之，糖尿病患者异常严重的血脂异常和假性肢端肥大症过度生长应引起医生警惕脂肪营养不良的可能性。先前未报道的致病性p.Cys48Arg突变和已知的p.Leu228Pro突变都导致发育中的脂肪细胞中AGPAT 2蛋白表达降低。最有可能的是，在这些突变的纯合携带者中观察到的CGL在很大程度上是由蛋白质表达的丧失引起的。
Loss-of-function mutations in AGPAT2, encoding 1-acylglycerol-3-phosphate-O-acyltransferase 2 (AGPAT2), produce congenital generalised lipodystrophy (CGL). We screened the AGPAT2 gene in two siblings who presented with pseudoacromegaly, diabetes and severe dyslipidaemia and identified a novel mutation in AGPAT2 causing a single amino acid substitution, p.Cys48Arg. We subsequently investigated the molecular pathogenic mechanism linking both this mutation and the previously reported p.Leu228Pro mutation to clinical disease. Wild-type and mutant AGPAT2 were expressed in control and AGPAT2-deficient preadipocyte cell lines. mRNA and protein expression was determined, and the ability of each AGPAT2 species to rescue adipocyte differentiation in AGPAT2-deficient cells was assessed. Protein levels of both p.Cys48Arg and p.Leu228Pro AGPAT2 were significantly reduced compared with that of wild-type AGPAT2 despite equivalent mRNA levels. Stable expression of wild-type AGPAT2 partially rescued adipogenesis in AGPAT2 deficient preadipocytes, whereas stable expression of p.Cys48Arg or p.Leu228Pro AGPAT2 did not. In conclusion, unusually severe dyslipidaemia and pseudoacromegaloid overgrowth in patients with diabetes should alert physicians to the possibility of lipodystrophy. Both the previously unreported pathogenic p.Cys48Arg mutation in AGPAT2, and the known p.Leu228Pro mutation result in decreased AGPAT2 protein expression in developing adipocytes. It is most likely that the CGL seen in homozygous carriers of these mutations is largely accounted for by loss of protein expression.