Insulin-degrading enzyme is not secreted from cultured cells.
Insulin-degrading enzyme is not secreted from cultured cells.
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培养细胞不分泌胰岛素降解酶。
DOI：
10.1038/s41598-018-20597-6
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发表时间：
2018
影响因子：
4.6
通讯作者：
Hersh,LouisB
中科院分区：
文献类型：
--
作者：
Song,EunSuk;Rodgers,DavidW;Hersh,LouisB
胰岛素降解酶（IDE）在生物活性肽的催化过程中起作用。确定的作用包括降解胰岛素和淀粉样β肽（Aβ），将其与糖尿病和阿尔茨海默病联系起来。IDE主要位于胞质溶胶中，一个长期存在的问题是它如何获得其肽底物。研究表明IDE通过非常规途径参与胰岛素和Aβ的胞外水解。我们发现培养的HEK-293或BV-2细胞释放的IDE仅占总细胞IDE的约1%，远低于先前报道的水平。重要的是，乳酸脱氢酶（LDH）和其他细胞溶质酶以相同的相对水平释放，表明细胞外IDE是由细胞完整性丧失而不是分泌引起的。如所报道的，洛伐他汀增加BV-2细胞的IDE释放，但这种释放通过LDH释放反映。细胞活力测定表明洛伐他汀导致细胞完整性的丧失，解释了其对IDE释放的影响。IDE存在于BV-2细胞条件培养基的外泌体富集组分中，但其仅占总细胞酶的约0.01%，不太可能是IDE的重要来源。这些结果对IDE的分泌及其在胞外肽降解中的重要性提出了质疑。
Insulin-degrading enzyme (IDE) functions in the catabolism of bioactive peptides. Established roles include degrading insulin and the amyloid beta peptide (Aβ), linking it to diabetes and Alzheimer’s disease. IDE is primarily located in the cytosol, and a longstanding question is how it gains access to its peptide substrates. Reports suggest that IDE secreted by an unconventional pathway participates in extracellular hydrolysis of insulin and Aβ. We find that IDE release from cultured HEK-293 or BV-2 cells represents only ~1% of total cellular IDE, far less than has been reported previously. Importantly, lactate dehydrogenase (LDH) and other cytosolic enzymes are released at the same relative level, indicating that extracellular IDE results from a loss of cell integrity, not secretion. Lovastatin increases IDE release from BV-2 cells as reported, but this release is mirrored by LDH release. Cell viability assays indicate lovastatin causes a loss of cell integrity, explaining its effect on IDE release. IDE is present in an exosome-enriched fraction from BV-2 cell conditioned media, however it represents only ~0.01% of the total cellular enzyme and is unlikely to be a significant source of IDE. These results call into question the secretion of IDE and its importance in extracellular peptide degradation.