HOIPIN-1 (JTP0819958) is a selective and potent inhibitor of linear ubiquitin chain assembly complex (LUBAC) (IC50 >2.8 μM).HOIPIN-1 inhibits LUBAC-mediated NF-kB activation.

In the HTRF-based analysis of LUBAC-mediated ubiquitination using Petit-LUBAC, the preincubation time of HOIPIN-1 (0.9-120 μM) in the reaction buffer correlates with increased inhibitory activity. The IC50 values at 1 h, 3 h, 6 h, and 24 h are 26 μM, 26 μM, 26 μM, and 3.926 μM, respectively[1].
Co-expression of LUBAC subunits in HEK293T cells increases the level of intracellular linear polyubiquitin chains. HOIPIN-1 (1-30 μM) dose-dependently inhibits the production of intracellular linear polyubiquitin chains in HEK293T cells expressing LUBAC[1].
In HeLa cells, HOIPIN-1 (30-100 μM; 30-60 minutes) inhibits IL-1β-induced NF-κB activation and reduces the phosphorylation of IKKα/β, p105, and p65. Furthermore, at doses of 10-100 μM, HOIPIN-1 dose-dependently inhibits the expression of NF-κB target genes such as ICAM1 and TNF-α induced by IL-1β in HeLa cells[1].
The linear ubiquitin chain assembly complex (LUBAC) consists of HOIL-1L, HOIP, and SHARPIN subunits. HOIPIN-1 inhibits the linear polyubiquitination activity of the HOIL-1L/HOIP complex, HOIL-1L/HOIP/SHARPIN complex, and HOIP/SHARPIN complex with IC50 values of 4.4 μM, 3.5 μM, and 3.7 μM, respectively[2].
In A549 cells, HOIPIN-1 (1-100 μM; 72 hours) shows no apparent cytotoxicity based on ATP content. However, it exhibits cytotoxicity in A549 cells with an IC50 > 100 μM[2].