From the King's British Heart Foundation Centre, King's College London, United Kingdom (X.Y., A.L.F., J.B.-B., R.L., M.F., F.B., P.S., Q.X., M.M.).
Department of Medical Biochemistry, Amsterdam Cardiovascular Sciences (S.W., C.J.M.d.V., V.d.W.), Amsterdam UMC, University of Amsterdam, the Netherlands.
Arterioscler Thromb Vasc Biol. 2019 Sep;39(9):1859-1873. doi: 10.1161/ATVBAHA.118.312175. Epub 2019 Jul 18.
Marfan syndrome (MFS) is caused by mutations in FBN1 (fibrillin-1), an extracellular matrix (ECM) component, which is modified post-translationally by glycosylation. This study aimed to characterize the glycoproteome of the aortic ECM from patients with MFS and relate it to aortopathy. Approach and Results: ECM extracts of aneurysmal ascending aortic tissue from patients with and without MFS were enriched for glycopeptides. Direct N-glycopeptide analysis by mass spectrometry identified 141 glycoforms from 47 glycosites within 35 glycoproteins in the human aortic ECM. Notably, MFAP4 (microfibril-associated glycoprotein 4) showed increased and more diverse N-glycosylation in patients with MFS compared with control patients. MFAP4 mRNA levels were markedly higher in MFS aortic tissue. MFAP4 protein levels were also increased at the predilection (convexity) site for ascending aorta aneurysm in bicuspid aortic valve patients, preceding aortic dilatation. In human aortic smooth muscle cells, MFAP4 mRNA expression was induced by TGF (transforming growth factor)-β1 whereas siRNA knockdown of MFAP4 decreased FBN1 but increased elastin expression. These ECM changes were accompanied by differential gene expression and protein abundance of proteases from ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family and their proteoglycan substrates, respectively. Finally, high plasma MFAP4 concentrations in patients with MFS were associated with a lower thoracic descending aorta distensibility and greater incidence of type B aortic dissection during 68 months follow-up.
Our glycoproteomics analysis revealed that MFAP4 glycosylation is enhanced, as well as its expression during the advanced, aneurysmal stages of MFS compared with control aneurysms from patients without MFS.
马凡综合征（MFS）是由 FBN1（原纤维蛋白 1）基因突变引起的，FBN1 是细胞外基质（ECM）的组成部分，其在翻译后通过糖基化进行修饰。本研究旨在对 MFS 患者的主动脉 ECM 的糖蛋白组进行特征分析，并将其与主动脉病变相关联。
从 MFS 患者和无 MFS 患者的动脉瘤性升主动脉组织中提取 ECM 提取物，对糖肽进行富集。通过质谱法直接对 N-糖肽进行分析，在人类主动脉 ECM 中的 35 种糖蛋白中鉴定出 47 个糖基化位点的 141 种糖型。值得注意的是，与对照组患者相比，MFAP4（微纤维相关糖蛋白 4）在 MFS 患者中表现出更高和更多样的 N-糖基化。在 MFS 主动脉组织中，MFAP4mRNA 水平明显升高。在二叶主动脉瓣患者升主动脉瘤的易患部位（凸面），MFAP4 蛋白水平也升高，先于主动脉扩张。在人主动脉平滑肌细胞中，TGF（转化生长因子）-β1 诱导 MFAP4mRNA 表达，而 MFAP4 的 siRNA 敲低降低了 FBN1 但增加了弹性蛋白的表达。这些 ECM 变化伴随着 ADAMTS（含血栓反应蛋白基序的解整合素和金属蛋白酶）家族蛋白酶及其蛋白聚糖底物的差异基因表达和蛋白丰度。最后，MFS 患者的高血浆 MFAP4 浓度与 68 个月随访期间较低的胸降主动脉扩张性和更大的 B 型主动脉夹层发生率相关。
我们的糖蛋白组学分析表明，与无 MFS 的对照组患者的动脉瘤相比，MFAP4 糖基化在 MFS 的晚期、动脉瘤阶段增强，并且其表达也增强。
