Biochemical characterization of vitreous and cardiac amyloid in Ile84Ser transthyretin amyloidosis
Biochemical characterization of vitreous and cardiac amyloid in Ile84Ser transthyretin amyloidosis
复制标题
DOI：
10.1080/13506120600877003
复制
发表时间：
2006-09-01
影响因子：
5.5
通讯作者：
Benson, Merrill D.
中科院分区：
文献类型：
--
作者：
Liepnieks, Yuris J.;Wilson, Donald L.;Benson, Merrill D.
血浆甲状腺素运载蛋白（TTR）在肝脏中合成，并且是TTR淀粉样变性中内脏淀粉样沉积物的来源。然而，TTR也在眼睛的视网膜色素上皮和大脑的脉络丛中合成。据推测，玻璃体淀粉样蛋白与约20%的已知淀粉样蛋白TTR突变有关，是由眼内TTR的局部合成引起的。为了阐明器官间淀粉样蛋白的差异是否存在，我们分析了Ile 84 Ser TTR患者的玻璃体和心脏淀粉样蛋白原纤维进行比较。从分离的玻璃体和心脏淀粉样原纤维的盐酸胍溶解的蛋白质的分析表明，在这两个器官中的淀粉样TTR是高度蛋白水解与少量的完整的TTR存在。虽然玻璃体蛋白适合于直接Edman序列分析，但心脏蛋白的产率较低，表明它主要是N-末端封闭的或无法进行Edman降解。虽然玻璃体含有主要的11 kDa和次要的9 kDa片段，但心脏含有至少三个7-11 kDa的主要片段。维生素蛋白在Lys 48-Thr 49之间被切割，而心脏蛋白在残基46-52区域的多个位点被切割。虽然两种组织中的沉积物都富含变体TTR，但玻璃体原纤维比心脏原纤维含有更多的变体蛋白（80-89% vs. 60- 65%Ser84TTR）。这些差异表明，原纤维形成的机制或途径可能在不同的组织中不同。
Plasma transthyretin (TTR) is synthesized in the liver and is the source for visceral amyloid deposits in TTR amyloidosis. However, TTR is also synthesized in the retinal pigment epithelium of the eye and choroid plexus of the brain. It has been postulated that vitreous amyloid, which is associated with approximately 20% of the known amyloidogenic TTR mutations, results from local synthesis of TTR in the eye. In order to elucidate if differences in amyloid between organs exists, we have analyzed vitreous and cardiac amyloid fibrils in Ile84Ser TTR patients for comparison. Analysis of guanidine hydrochloride solubilized protein from isolated vitreous and cardiac amyloid fibrils indicated that the amyloid TTR in both organs is highly proteolyzed with minor amounts of intact TTR present. While vitreous protein was amenable to direct Edman sequence analysis, cardiac protein gave low yields indicating it was mostly N-terminally blocked or inaccessible to Edman degradation. While vitreous contained major 11 kDa and minor 9 kDa fragments, cardiac contained at least three major fragments of 7-11 kDa. Vitreous protein was cleaved between Lys48-Thr49, while cardiac protein was cleaved at multiple sites in the residue 46-52 region. While deposits in both tissues were enriched in variant TTR, vitreous fibrils contained more variant protein than cardiac fibrils (80-89% vs. 60-65% Ser84TTR). These differences suggest that the mechanism or pathway of fibril formation may differ in various tissues.