Department of Biomedicine, Aarhus University, Aarhus, Denmark.
Departments of Medicine and Physiology, Johns Hopkins School of Medicine, Baltimore, Maryland.
J Am Soc Nephrol. 2021 Sep;32(9):2195-2209. doi: 10.1681/ASN.2020071035. Epub 2021 Jul 6.
Urinary extracellular vesicles (uEVs) are secreted into urine by cells from the kidneys and urinary tract. Although changes in uEV proteins are used for quantitative assessment of protein levels in the kidney or biomarker discovery, whether they faithfully reflect (patho)physiologic changes in the kidney is a matter of debate.
Mass spectrometry was used to compare in an unbiased manner the correlations between protein levels in uEVs and kidney tissue from the same animal. Studies were performed on rats fed a normal or high K diet.
Absolute quantification determined a positive correlation (Pearson =0.46 or 0.45, control or high K respectively, <0.0001) between the approximately 1000 proteins identified in uEVs and corresponding kidney tissue. Transmembrane proteins had greater positive correlations relative to cytoplasmic proteins. Proteins with high correlations (>0.9), included exosome markers Tsg101 and Alix. Relative quantification highlighted a monotonic relationship between altered transporter/channel abundances in uEVs and the kidney after dietary K manipulation. Analysis of genetic mouse models also revealed correlations between uEVs and kidney.
This large-scale unbiased analysis identifies uEV proteins that track the abundance of the parent proteins in the kidney. The data form a novel resource for the kidney community and support the reliability of using uEV protein changes to monitor specific physiologic responses and disease mechanisms.
尿细胞外囊泡(uEVs)由肾脏和泌尿道细胞分泌到尿液中。虽然 uEV 蛋白的变化可用于定量评估肾脏中的蛋白水平或发现生物标志物,但它们是否能真实反映肾脏的(病理)生理变化仍存在争议。
采用质谱法以无偏倚的方式比较同一动物的 uEV 与肾脏组织中蛋白水平的相关性。该研究在给予正常或高钾饮食的大鼠中进行。
绝对定量确定了 uEV 中约 1000 种鉴定蛋白与相应肾脏组织之间的正相关(Pearson =0.46 或 0.45,分别为对照或高钾,<0.0001)。跨膜蛋白与细胞质蛋白相比具有更大的正相关性。具有高相关性(>0.9)的蛋白包括外泌体标志物 Tsg101 和 Alix。相对定量强调了饮食钾干预后 uEV 中转运体/通道丰度改变与肾脏之间的单调关系。对遗传小鼠模型的分析也揭示了 uEV 与肾脏之间的相关性。
这项大规模的无偏分析确定了可跟踪肾脏中亲代蛋白丰度的 uEV 蛋白。该数据为肾脏研究社区提供了一个新的资源,并支持使用 uEV 蛋白变化来监测特定生理反应和疾病机制的可靠性。