Department of Internal Medicine, Inje University Haeundae Paik Hospital, 1435, Jwa-dong, Haeundae-gu, Busan, 612-030, Korea.
Clin Exp Nephrol. 2013 Aug;17(4):575-81. doi: 10.1007/s10157-012-0751-y. Epub 2012 Dec 11.
Anemia in chronic renal failure results from inadequate production of erythropoietin and decrease in its biological activity, and the reduced activity of erythropoietin is caused by the presence of plasma inhibitors of erythropoietin. It is reported that one of the inhibitors of erythropoietin is cyanate, a potential uremic toxin formed spontaneously from increased urea due to decreased renal function, and erythropoietin loses its biological activity due to negatively charged cyanate. The purpose of this study is to investigate the protective effects of amino acids, positively charged amino groups, and albumin binding of several toxins on erythropoietin carbamoylation.
The degree of change in erythropoietin structure by cyanate was measured by the trinitrobenzenesulphonate reaction and Western blotting. The loss of biological activity of erythropoietin caused by cyanate was measured by injecting erythropoietin into rats with chronic renal failure.
The free amino groups in erythropoietin decreased under cyanate treatment in a time- and concentration-dependent manner. In the cyanate treatment group, of the twenty amino acids, phenylalanine, valine, tryptophan, threonine, and lysine prevented the structural modification of erythropoietin, according to Western blot analysis. In addition, of the three proteins, albumin prevented the structural modification of erythropoietin. As for the cyanate with erythropoietin treatment group, only lysine and albumin prevented the loss of biological activity of erythropoietin in the rats.
The results of this study suggest that lysine and albumin may play a protective role against renal anemia by erythropoietin carbamoylation in chronic renal failure.
慢性肾衰竭导致的贫血是由于促红细胞生成素产生不足和其生物活性降低所致，而促红细胞生成素活性降低是由于存在促红细胞生成素的血浆抑制剂。据报道，促红细胞生成素的抑制剂之一是氰酸盐，它是由于肾功能下降导致尿素增加而自发形成的潜在尿毒症毒素，由于带负电荷的氰酸盐，促红细胞生成素失去其生物活性。本研究旨在探讨几种毒素的氨基酸、正电荷氨基和白蛋白结合对促红细胞生成素氨基甲酰化的保护作用。
通过三硝基苯磺酸反应和 Western blot 测定氰酸盐对促红细胞生成素结构变化的程度。通过向慢性肾衰竭大鼠注射促红细胞生成素来测定氰酸盐对促红细胞生成素生物活性的丧失。
在氰酸盐处理下，促红细胞生成素中的游离氨基基团呈时间和浓度依赖性减少。在氰酸盐处理组中，根据 Western blot 分析，二十种氨基酸中的苯丙氨酸、缬氨酸、色氨酸、苏氨酸和赖氨酸可防止促红细胞生成素的结构修饰。此外，在三种蛋白质中，白蛋白可防止促红细胞生成素的结构修饰。对于与促红细胞生成素一起处理的氰酸盐组，只有赖氨酸和白蛋白可防止大鼠促红细胞生成素生物活性的丧失。
本研究结果表明，赖氨酸和白蛋白可能通过慢性肾衰竭中促红细胞生成素的氨基甲酰化发挥保护作用，防止肾性贫血。
