Martin-Luther University Halle-Wittenberg, Department of Cardiothoracic Surgery, Ernst-Grube Str. 40, D-06120 Halle/Saale, Germany.
Int J Biochem Cell Biol. 2010 May;42(5):749-54. doi: 10.1016/j.biocel.2010.01.012. Epub 2010 Jan 18.
Advanced glycation end products (AGEs) are formed by the non-enzymatic glycation of proteins by reducing carbohydrates or alpha-oxo-aldehydes such as glyoxal and methylglyoxal and further rearrangements, eliminations and oxidations. AGE-modifications alter peptide structure, function and stability and accumulate under several pathophysiological conditions such as diabetes and are considered a biomarker of ageing. PDGF is a major regulator of wound healing, which is impaired in hyperglycaemia and ageing. We analyzed whether glycated PDGF has impaired activity in cell culture models and occurs in human subjects. PDGF was AGE-modified by the alpha-oxo-aldehydes glyoxal and methylglyoxal, which was shown by Western-blotting using alpha-carboxymethyllysine (CML) or alpha-arginine-pyrimidine (Arg-Pyr) antibodies. In mouse AKR-2B fibroblasts, this AGE-modified PDGF exhibited reduced signalling to AKT and ERK resulting in decreased cell proliferation. In the human osteosarcoma cell line 143B, PDGF signalling towards the AKT-kinase was decreased when using modified PDGF-AA, -AB, and -BB whereas the constitutive active ERK was not affected. Secreted proteins from collagen-activated platelets from diabetic subjects contained more CML-modified proteins compared to healthy controls. PDGF protein as a platelet protein coprecipitated in immunoprecipitation experiments with alpha-CML-antiserum. In summary, our data suggest that AGE-modification of PDGF contributes to reduced wound healing in diabetic patients.
糖基化终产物（AGEs）是由还原糖或α-氧代醛（如乙二醛和甲基乙二醛）非酶糖化蛋白质，并进一步重排、消除和氧化形成的。AGE 修饰改变了肽的结构、功能和稳定性，并在糖尿病等几种病理生理条件下积累，被认为是衰老的生物标志物。PDGF 是伤口愈合的主要调节剂，在高血糖和衰老中受损。我们分析了糖基化 PDGF 在细胞培养模型中是否活性受损以及是否发生在人体中。PDGF 被α-氧代醛乙二醛和甲基乙二醛糖基化，这通过使用α-羧甲基赖氨酸（CML）或α-精氨酸嘧啶（Arg-Pyr）抗体的 Western blot 显示。在小鼠 AKR-2B 成纤维细胞中，这种糖基化 PDGF 对 AKT 和 ERK 的信号转导减少，导致细胞增殖减少。在人骨肉瘤细胞系 143B 中，当使用修饰的 PDGF-AA、-AB 和 -BB 时，PDGF 向 AKT-激酶的信号转导减少，而组成性激活的 ERK 不受影响。与健康对照组相比，来自糖尿病患者胶原激活血小板的分泌蛋白中含有更多的 CML 修饰蛋白。PDGF 蛋白作为血小板蛋白，在与α-CML 抗血清的免疫沉淀实验中共同沉淀。总之，我们的数据表明，PDGF 的 AGE 修饰导致糖尿病患者伤口愈合减少。
