STING inhibitor

Mechanism of action of H-151-mediated STING inhibition

STING inhibitor

H-151 is a potent, irreversible, and selective small-molecule inhibitor of STING [1], a key sensor of cytosolic nucleic acids.  STING is a transmembrane protein found in the endoplasmic reticulum. Upon activation, it functions as a signaling hub, orchestrating immune responses to pathogenic, tumoral, or self-DNA detected in the cytoplasm [2].
 

Mode of action:

H-151 exerts its inhibitory action by covalently binding to STING at the transmembrane cysteine residue at position 91. This synthetic indole-derivative blocks STING palmitoylation and clustering, two essential steps for STING signaling.  In models of autoinflammatory disease, H-151 blocks STING‑induced expression of pro-inflammatory cytokines and reduces inflammation [1]. 
 

Key features:

• H-151 potently inhibits both human and murine STING, in vitro and in vivo (mouse models)
• H-151 strongly reduces STING-mediated but not RIG-I-mediated Interferon-β production
• H-151 blocks the activity of all STING variants tested
• InvitroFit™ grade: each lot is highly pure (≥95%) and functionally tested

 Read our review: Follow the path to STING

References:

1. Haag S.M. et al., 2018. Targeting STING with covalent small-molecule inhibitors. Nature 559:269-73.
2. Ishikawa H. & Barber G.N. 2008. STING is an endoplasmic reticulum adaptor that facilitates innate immune signalling. Nature 455:674-8.

Figures

Effect of H-151 on the IRF response of THP1-Dual™ cells to 2’3’-cGAMP. THP1-Dual™ cells were incubated with 20  µg/ml of 2’3’-cGAMP and increasing concentrations of H-151. After overnight incubation, the IRF response has been assessed by determining Lucia luciferase activity in the supernatant using QUANTI-Luc™. Data are shown as percentage (%) inhibition.

H-151 specifically inhibits STING activity. : THP1-Dual™ cells and B: RAW-Lucia™ ISG cells were incubated with 20 µg/ml of 2’3’-cGAMP, 7.5 µg/ml of 3’3’-cGAMP Fluorinated, 7.5 µg/ml of 2’3’-c-di-AM(PS)2 (Rp,Rp) or 1 µg/ml of 3p-hpRNA/LyoVec™, in the presence or absence of H-151 at 130 ng/ml (0.47 µM). The RIG-I ligand 3p-hpRNA was delivered into the cytoplasm using the cationic lipid transfection reagent, LyoVec™. After overnight incubation, the IRF response was assessed by determining Lucia luciferase activity in the supernatant using the detection reagent QUANTI-Luc™. Data are shown as percentage (%) activity.

H-151 inhibits the activity of multiple human STING variants. THP1-Dual™ and THP1-Dual™ KI-STING cells were incubated in the presence or absence of  400  ng/ml of H-151. THP1-Dual™ and THP1-Dual™ KI-STING-R232 cells were further incubated with 7.5  µg/ml of  3’3’-cGAMP Fluorinated while THP1-Dual™ KI-STING-S154 and THP1-Dual™  KI-STING-M155 cells were not incubated with a STING ligand as they constitutively express activated STING. After overnight incubation, the IRF response was assessed by monitoring Lucia luciferase activity using the detection reagent QUANTI-Luc™. Data are shown as percentage (%) activity.

Effect of H-151 on the NF-κB response of THP1-Dual™ cells to 2’3’-c-di-AM(PS)₂ (Rp,Rp).  THP1-Dual™ cells were incubated with 7.5 µg/ml of 2’3’-c-di-AM(PS)2 (Rp,Rp) or 1 µg/ml of 3p-hpRNA/LyoVec™, in the presence or absence of H-151 at 130 ng/ml (0.47 µM).  The RIG-I ligand 3p-hpRNA was delivered into the cytoplasm using the cationic lipid transfection reagent, LyoVec™.  After a 24h incubation, NF-kB activation was determined using QUANTI-Blue™, a SEAP detection reagent, and by reading the optical density (OD) at 630 nm.

Specifications

Working concentration: 4 ng/ml (15 nM) to 4 μg/ml (15 μM) for cell culture assays

CAS number: 941987-60-6

Synonym: N-(4-Ethylphenyl)-N’-1H-indol-3-yl-urea

Solubility: 20 mg/ml (71.60 mM) in DMSO

Formula: C₁₇H₁₇N₃O

Molecular weight: 279.34 g/mol

Quality control:

• Purity ≥ 95% (UHPLC)
• The inhibitory activity has been validated using cellular assays.
• The absence of bacterial contamination (e.g. lipoproteins and endotoxins) has been confirmed using HEK-Blue™ TLR2 and HEK-Blue™ TLR4 cells.

Contents

H-151 is available in two quantities:

• inh-h151: 10 mg
• inh-h151-5: 5 x 10 mg

​ H-151 is shipped at room temperature.

Upon receipt, store at -20°C.

Details

Chemical structure of H-151: