Enzymatic processing of angiotensin peptides by human glomerular endothelial cells.
Enzymatic processing of angiotensin peptides by human glomerular endothelial cells.
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人肾小球内皮细胞对血管紧张素肽的酶促加工。
DOI：
10.1152/ajprenal.00087.2012
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
Janech,MichaelG
中科院分区：
文献类型：
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作者：
Velez,JuanCarlosQ;Ierardi,JessalynL;Bland,AlisonM;Morinelli,ThomasA;Arthur,JohnM;Raymond,JohnR;Janech,MichaelG
肾小球内的肾素-血管紧张素系统（RAS）与进行性肾小球疾病的发病机制有关。肾小球足细胞和系膜细胞在血管紧张素（ANG）肽的代谢中起着不同的作用。然而，我们对肾小球内皮细胞（GEnCs）的RAS酶能力的理解仍然不完整。我们探讨了内源性切割ANG底物在培养的人GEnCs（hGEnCs）使用基质辅助激光解吸/电离飞行时间质谱和同位素标记的肽定量的机制。总的来说，hGEnCs代谢ANG II的速率明显低于足细胞，而ANG I的加工速率在肾小球细胞类型之间相当。ANG Ⅱ是ANG Ⅰ最丰富的片段，ANG-（1-7）含量较少。血管紧张素转化酶（ACE）抑制剂可显著抑制血管紧张素Ⅱ（ANG Ⅱ）的生成，脯氨酰内肽酶（PEP）抑制剂可降低ANG-（1-7）的生成，但脑啡肽酶抑制剂则无此作用。ANG II的裂解导致部分转化为ANG-（1-7），这一过程可被ACE 2抑制剂以及PEP和脯氨酰羧肽酶抑制剂减弱。ACE介导ANG-（1-7）进一步断裂为ANG-（1-5）。此外，通过检测APN抑制剂对ANG III转化为ANG IV的改善，证明了氨肽酶N活性（APN）的证据。虽然我们没有发现氨肽酶A的表达或活性，但检测到归因于乙酰氨基肽酶的适度活性。证实了相关酶的信使RNA和基因表达。这些结果表明，hGEnCs具有突出的ACE活性，但适度的ANG II代谢活性相比，足细胞。PEP、ACE 2、脯氨酰羧肽酶、APN和脯氨酰氨基肽酶也是hGEnC中包含的参与膜结合ANG肽切割的酶。肾小球内特定细胞类型的损伤可能改变肾内RAS平衡。
The intraglomerular renin-angiotensin system (RAS) is linked to the pathogenesis of progressive glomerular diseases. Glomerular podocytes and mesangial cells play distinct roles in the metabolism of angiotensin (ANG) peptides. However, our understanding of the RAS enzymatic capacity of glomerular endothelial cells (GEnCs) remains incomplete. We explored the mechanisms of endogenous cleavage of ANG substrates in cultured human GEnCs (hGEnCs) using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and isotope-labeled peptide quantification. Overall, hGEnCs metabolized ANG II at a significantly slower rate compared with podocytes, whereas the ANG I processing rate was comparable between glomerular cell types. ANG II was the most abundant fragment of ANG I, with lesser amount of ANG-(1–7) detected. Formation of ANG II from ANG I was largely abolished by an ANG-converting enzyme (ACE) inhibitor, whereas ANG-(1–7) formation was decreased by a prolylendopeptidase (PEP) inhibitor, but not by a neprilysin inhibitor. Cleavage of ANG II resulted in partial conversion to ANG-(1–7), a process that was attenuated by an ACE2 inhibitor, as well as by an inhibitor of PEP and prolylcarboxypeptidase. Further fragmentation of ANG-(1–7) to ANG-(1–5) was mediated by ACE. In addition, evidence of aminopeptidase N activity (APN) was demonstrated by detecting amelioration of conversion of ANG III to ANG IV by an APN inhibitor. While we failed to find expression or activity of aminopeptidase A, a modest activity attributable to aspartyl aminopeptidase was detected. Messenger RNA and gene expression of the implicated enzymes were confirmed. These results indicate that hGEnCs possess prominent ACE activity, but modest ANG II-metabolizing activity compared with that of podocytes. PEP, ACE2, prolylcarboxypeptidase, APN, and aspartyl aminopeptidase are also enzymes contained in hGEnCs that participate in membrane-bound ANG peptide cleavage. Injury to specific cell types within the glomeruli may alter the intrarenal RAS balance.