Huang Z Q, Sanders P W
Department of Veterans Affairs Medical Center, Birmingham, Alabama 35233, USA.
J Clin Invest. 1997 Feb 15;99(4):732-6. doi: 10.1172/JCI119218.
Cast nephropathy is a severe complication of multiple myeloma. Binding of filtered monoclonal light chains (LC) with Tamm-Horsfall glycoprotein (THP) triggers heterotypic aggregation of these two proteins to form casts in the distal nephron of the kidney. To localize the LC binding site on THP, human THP was deglycosylated and underwent limited trypsin digestion in the presence or absence of a nephrotoxic LC known to bind THP. A 29.6-kD band was protected from trypsin digestion by the addition of LC. NH2-terminal amino acid sequence and amino acid analyses revealed this band was located between the 6th and 287th amino acid residues of THP. Six peptides located within this 29.6-kD fragment were synthesized and used as potential inhibitors of binding or aggregation of five different nephrotoxic LCs with THP. Peptide AHWSGHCCL (from amino acid 225 to 233) completely inhibited binding and aggregation of these proteins. Optimal inhibition required a cystine residue in this peptide. Truncation experiments demonstrated the entire sequence was necessary for ideal inhibition and the histidine residue explained the effects of pH on binding. These studies provided a basis for further study of LC-THP interaction and a potential approach toward the prevention of cast nephropathy.
管型肾病是多发性骨髓瘤的一种严重并发症。滤过的单克隆轻链（LC）与Tamm-Horsfall糖蛋白（THP）结合会触发这两种蛋白的异型聚集，从而在肾脏远端肾单位形成管型。为了定位LC在THP上的结合位点，对人THP进行了去糖基化处理，并在存在或不存在已知可与THP结合的肾毒性LC的情况下进行了有限的胰蛋白酶消化。添加LC可保护一条29.6-kD的条带不被胰蛋白酶消化。氨基末端氨基酸序列和氨基酸分析表明，该条带位于THP的第6个至第287个氨基酸残基之间。合成了位于这个29.6-kD片段内的6个肽，并将其用作5种不同肾毒性LC与THP结合或聚集的潜在抑制剂。肽AHWSGHCCL（氨基酸225至233）完全抑制了这些蛋白的结合和聚集。最佳抑制需要该肽中的一个胱氨酸残基。截短实验表明，完整序列对于理想抑制是必需的，并且组氨酸残基解释了pH对结合的影响。这些研究为进一步研究LC-THP相互作用以及预防管型肾病的潜在方法提供了基础。
