Diabetes is associated with posttranslational modifications in plasminogen resulting in reduced plasmin generation and enzyme-specific activity

• Published in: Blood Vol. 122; no. 1; pp. 134 - 142
• Main Authors: Ajjan, Ramzi A., Gamlen, Toby, Standeven, Kristina F., Mughal, Salihah, Hess, Katharina, Smith, Kerrie A., Dunn, Emma J., Anwar, M. Maqsud, Rabbani, Naila, Thornalley, Paul J., Philippou, Helen, Grant, Peter J.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 04.07.2013
• Subjects: Diabetes Mellitus, Type 1 - blood; Enzyme Activation - physiology; Fibrinogen - metabolism; Fibrinolysin - biosynthesis; Fibrinolysis - physiology; Glycosylation; Humans; Mucoproteins - metabolism; Plasminogen - genetics; Plasminogen - metabolism; Protein Binding - physiology; Protein Processing, Post-Translational - physiology; Thrombosis - blood
• ISSN: 0006-4971; 1528-0020; 1528-0020
• DOI: 10.1182/blood-2013-04-494641

Diabetes is associated with hypofibrinolysis by mechanisms that are only partially understood. We investigated the effects of in vivo plasminogen glycation on fibrinolysis, plasmin generation, protein proteolytic activity, and plasminogen-fibrin interactions. Plasma was collected from healthy controls and individuals with type 1 diabetes before and after improving glycemia. Plasma-purified plasmin(ogen) functional activity was evaluated by chromogenic, turbidimetric, and plasmin conversion assays, with surface plasmon resonance employed for fibrin-plasminogen interactions. Plasminogen posttranslational modifications were quantified by mass spectrometry and glycation sites located by peptide mapping. Diabetes was associated with impaired plasma fibrin network lysis, which partly normalized upon improving glycaemia. Purified plasmin(ogen) from diabetic subjects had impaired fibrinolytic activity compared with controls (723 ± 16 and 317 ± 4 s, respectively; P < .01), mainly related to decreased fibrin-dependent plasmin generation and reduced protease activity (Kcat/KM 2.57 ± 1.02 × 10−3 and 5.67 ± 0.98 × 10−3 M−1s−1, respectively; P < .05). Nε-fructosyl-lysine residue on plasminogen was increased in diabetes compared with controls (6.26 ± 3.43 and 1.82 ± 0.95%mol, respectively; P < .01) with preferential glycation of lysines 107 and 557, sites involved in fibrin binding and plasmin(ogen) cleavage, respectively. Glycation of plasminogen in diabetes directly affects fibrinolysis by decreasing plasmin generation and reducing protein-specific activity, changes that are reversible with modest improvement in glycemic control. • Plasminogen is glycated in diabetes, resulting in reduced plasmin generation and impaired protein activity.• Impaired plasminogen function and the consequent hypofibrinolysis in diabetes are reversible by modest improvement in glycemia.