HOIPIN-1 (JTP-0819958) is a selective linear ubiquitin chain assembly complex (LUBAC) inhibitor with an IC50 of 2.8 μM[1]. HOIPIN-1 suppress LUBAC-mediated NF-kB activation in vitro[2].

In the HTRF-based LUBAC-mediated ubiquitination assay with Petit-LUBAC. HOIPIN-1 (0.9-120 μM) exhibits an increased inhibitory activity with a a longer preincubation time in the reaction buffer. The IC50 values are 26 μM, 26 μM, 26 μM, and 3.926 μM, at 1h, 3h, 6h and 24 h, respectively[1].The coexpression of the LUBAC subunits in HEK293T cells increases the intracellular amounts of linear polyubiquitin, HOIPIN-1 (1-30 μM) dose dependently suppressed the production of intracellular linear polyubiquitin in LUBAC-expressing HEK293T cells[1].HOIPIN-1 (30-100 μM; 30-60 mins) inhibits IL-1β-induced NF-κB activation and decreases the phosphorylation of IKKα/β, p105, and p65 in hela cells[1].HOIPIN-1 (10-100 μM) inhibits the expression of NF-κB target genes such as ICAM1 and TNF-α in IL-1β-induced hela cells in a dose-dependent manner[1].The linear ubiquitin chain assembly complex (LUBAC), composed of the HOIL-1L, HOIP, and SHARPIN subunits. HOIPIN-1 exhibits IC50 values of 4.4 μM, 3.5 μM and 3.7 μM for inhibition of linear polyubiquitination activity by the HOIL-1L/HOIP complex, the HOIL-1L/HOIP/SHARPIN complex and the HOIP/SHARPIN complex, respectively[2].HOIPIN-1 (1-100 μM; 72 hours) shows no apparent cytotoxicity based on ATP content, it exhibits cytotoxicity in A549 cells with an IC50>100 μM in A549 cells[2].

[1]. Ken Katsuya, et al. High-Throughput Screening for Linear Ubiquitin Chain Assembly Complex (LUBAC) Selective Inhibitors Using Homogenous Time-Resolved Fluorescence (HTRF)-Based Assay System. SLAS Discov. 2018 Dec;23(10):1018-1029
[2]. Ken Katsuya, et al. Small-molecule inhibitors of linear ubiquitin chain assembly complex (LUBAC), HOIPINs, suppress NF-κB signaling. Biochem Biophys Res Commun. 2019 Feb 12;509(3):700-706.