Neutrophil gelatinase-associated lipocalin (NGAL) has emerged as a promising biomarker for the early prediction of acute kidney injury (AKI). The production of recombinant NGAL is considered to be necessary for the development of a detection method. This study intended to express the recombinant NGAL protein in 293T cell under the Tet-On inducible system and human serum albumin signal sequence (HSA-SS). The transfection efficiency and protein modulation were assessed by detecting the expression of the enhanced green fluorescent protein (EGFP) and secreted NGAL protein. Both proteins were detected only in the presence of a doxycycline (Dox) inducer. Cell toxicity was not found under any conditions. Moreover, a higher level of soluble NGAL protein in the supernatant secreted by HSA-SS compared with a native signal peptide (Nat-SS) was observed. In summary, this work successfully optimized the conditions for induction of NGAL expression. This system will provide as an efficient strategy to produce other recombinant proteins secreted from a mammalian cell.

中文翻译：

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诱导性双重功能系统在293T细胞中分泌的中性粒细胞明胶酶相关的脂蛋白的表达

中性粒细胞明胶酶相关脂钙蛋白（NGAL）已成为早期预测急性肾损伤（AKI）的有前途的生物标志物。重组NGAL的产生被认为是开发检测方法所必需的。这项研究旨在在Tet-On诱导系统和人血清白蛋白信号序列（HSA-SS）下在293T细胞中表达重组NGAL蛋白。通过检测增强的绿色荧光蛋白（EGFP）和分泌的NGAL蛋白的表达来评估转染效率和蛋白调节。两种蛋白质仅在强力霉素（Dox）诱导剂存在下才能检测到。在任何条件下均未发现细胞毒性。此外，与天然信号肽（Nat-SS）相比，HSA-SS分泌的上清液中的可溶性NGAL蛋白水平更高。总之，这项工作成功地优化了诱导NGAL表达的条件。该系统将提供生产哺乳动物细胞分泌的其他重组蛋白的有效策略。