Transthyretin and amyloid in the islets of Langerhans in type-2 diabetes.
Transthyretin (TTR) is a major amyloid fibril protein in certain systemic forms of amyloidosis. It is a plasma protein, mainly synthesized by the liver but expression occurs also at certain minor locations, including the endocrine cells in the islets of Langerhans. With the use of immunohistochemistry and in situ hybridization, we have studied the distribution of transthyretin-containing cells in islets of Langerhans in type-2 diabetic and nondiabetic individuals. TTR expression was particularly seen in alpha (glucagon) cells. Islets from type-2 diabetic patients had proportionally more transthyretin-reactive islet cells, including beta cells. A weak transthyretin immunoreaction in IAPP-derived amyloid occurred in some specimens. In seeding experiments in vitro, we found that TTR fibrils did not seed IAPP while IAPP fibrils seeded TTR. It is suggested that islet expression of transthyretin may be altered in type-2 diabetes.
Westermark
Gunilla T
GT
Department of Clinical and Experimental Medicine, Linköping University, 581 85 Linköping, Sweden. per.westermark@genpat.uu.se
Westermark
Per
P
D019943:Amino Acid Substitution; D000682:Amyloid / Q000378:metabolism*; D000686:Amyloidosis / Q000378:metabolism / Q000473:pathology; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D050417:Insulin-Secreting Cells / Q000378:metabolism / Q000473:pathology; D058228:Islet Amyloid Polypeptide; D007515:Islets of Langerhans / Q000378:metabolism* / Q000473:pathology; D011228:Prealbumin / Q000235:genetics* / Q000378:metabolism*; D012016:Reference Values
D000682:Amyloid; D058228:Islet Amyloid Polypeptide; D011228:Prealbumin