Shield-1 is a specific, cell-permeable ligand for FK506-binding protein 12 (FKBP)[1]. Shield-1 reverses the instability of mutated FKBP by binding to FKBP, allowing for the conditional expression of the mtFKBP fusion protein[2]. Shield-1 can influence viral replication by modulating the stability of the mtFKBP fusion protein[3]. Shield-1 is also a commonly used gene-editing tool with the function of erasing RNA N6-methyladenosine modifications[4].
In vitro, treatment of NIH3T3 cells stably expressing the FKBP L106P fusion protein with Shield-1 (1µM) for 24 hours significantly reversed the protein degradation mediated by the destabilizing domain, restored the expression levels of RhoA and Cdc42 proteins, and induced stress fiber formation and pseudopod extension[5]. Treatment of HEK293 cells expressing the mtFKBP-TRPV5 fusion protein with Shield-1 (1µM) for 24 hours significantly reversed the protein degradation mediated by the mtFKBP domain, restoring the cell membrane expression and functional activity of the TRPV5 ion channel[6].
In vivo, systemic administration of Shield-1 (1µM) via the aquatic environment (water dosing) was used to stabilize a systemic DD-YFP fusion protein in Transgenic Medaka fish from the embryonic to adult stages. Shield-1 induced YFP reporter gene expression in a concentration-dependent manner in various organs, including the brain, gills, intestine, liver, kidney, spleen, heart, and gonads. Shield-1 effectively crossed the blood-brain barrier and successfully achieved protein stabilization in germ cells[7].
References:
[1] Madsen D, Jørgensen FP, Palmer D, et al. Design and Combinatorial Development of Shield-1 Peptide Mimetics Binding to Destabilized FKBP12. ACS Comb Sci. 2020 Mar 9;22(3):156-164.
[2] Li X, Wang S, Li Q, et al. A Rapid and Reversible Molecular "Switch" Regulating Protein Expression in Chlamydomonas reinhardtii. Plant Cell Environ. 2025 Jun;48(6):3913-3924.
[3] Schleiss MR, Fernández-Alarcón C, Bierle CJ, et al. Replication-deficient whole-virus vaccines against cytomegalovirus induce protective immunity in a guinea pig congenital infection model. J Virol. 2025 Jul 22;99(7):e0020725.
[4] Xu Y, Wang Y, Liang FS. Site-Specific m6 A Erasing via Conditionally Stabilized CRISPR-Cas13b Editor. Angew Chem Int Ed Engl. 2023 Oct 23;62(43):e202309291.
[5] Banaszynski LA, Chen LC, Maynard-Smith LA, et al. A rapid, reversible, and tunable method to regulate protein function in living cells using synthetic small molecules. Cell. 2006 Sep 8;126(5):995-1004.
[6] Schoeber JP, van de Graaf SF, Lee KP, et al. Conditional fast expression and function of multimeric TRPV5 channels using Shield-1. Am J Physiol Renal Physiol. 2009 Jan;296(1):F204-11.
[7] Froschauer A, Kube L, Kegler A, et al. Tunable Protein Stabilization In Vivo Mediated by Shield-1 in Transgenic Medaka. PLoS One. 2015 Jul 6;10(7):e0131252.
Shield-1是一种特异性、细胞可渗透的FK506结合蛋白-12 (FKBP)配体[1]。通过与突变的FKBP结合而逆转其不稳定性，允许mtFKBP融合蛋白的条件表达[2]。Shield-1可通过调节mtFKBP融合蛋白的稳定性来影响病毒复制[3]。Shield-1还是一种常用的基因编辑工具，具有擦除RNA N6-甲基腺苷修饰的功能[4]。
在体外，Shield-1（1μM）处理稳定表达FKBP L106P融合蛋白的NIH3T3细胞24小时，可显著逆转由Dstabilizing domain 介导的蛋白降解作用，恢复RhoA、Cdc42蛋白的表达水平，并诱导细胞应力纤维形成、伪足延伸[5]。Shield-1（1μM）处理表达mtFKBP-TRPV5融合蛋白的HEK293细胞24小时，显著逆转由mtFKBP结构域介导的蛋白降解作用，恢复TRPV5离子通道的细胞膜表达及功能活性[6]。
在体内，Shield-1（10nM, 100nM, and 1µM）通过水体给药进行全身性处理，用于稳定Transgenic Medaka fish从胚胎到成鱼各发育阶段的全身性DD-YFP融合蛋白。Shield-1以浓度依赖的方式显著诱导了包括脑、鳃、肠、肝、肾、脾、心脏及性腺在内的多种器官中YFP报告基因的表达，并有效穿过血脑屏障，且在生殖细胞中成功实现蛋白稳定化[7]。