In silico screening of GMQ-like compounds reveals guanabenz and sephin1 as new allosteric modulators of acid-sensing ion channel 3

Abstract

In silico screening of GMQ-like compounds reveals guanabenz1 and sephin1 as new allosteric modulators of acid-sensing ion 2 channel 3 3 4 Abstract 16Acid-sensing ion channels (ASICs) are voltage-independent cation channels that 17 detect decreases in extracellular pH. Dysregulation of ASICs underpins a number 18 of pathologies. Of particular interest is ASIC3, which is recognised as the key 19 sensor of acid-induced pain and is instrumental in the establishment of pain 20 arising from inflammatory conditions, such as rheumatoid arthritis. Thus, the 21 identification of new ASIC3 modulators and the mechanistic understanding of 22 how these compounds modulate ASIC3 could be important for the development 23of new strategies to counteract the detrimental effects of dysregulated ASIC3 24 activity in inflammation. Here, we report the identification of novel ASIC3 25 modulators based on the ASIC3 specific agonist, 2-guanidine-4-26 methylquinazoline (GMQ). Through a GMQ-guided in silico screening of Food 27and Drug administration (FDA)-approved drugs, 5 compounds were selected and 28 tested for their possible modulation of rat ASIC3 (rASIC3) using whole-cell patch-29 clamp electrophysiology. Of the chosen drugs, guanabenz, an α2-adrenoceptor 30 agonist, produced similar effects to GMQ on rASIC3, activating the channel at 31 neutral pH and potentiating its response to mild acidic stimuli. Sephin1, a 32 guanabenz derivative that lacks α2-adrenoceptor activity, has been proposed to 33 act as a selective inhibitor of a regulatory subunit of the stress-induced protein 34 phosphatase 1 (PPP1R15A) with promising therapeutic potential for the 35 treatment of multiple sclerosis. However, we found that like guanabenz, sephin1 36 activates rASIC3 at neutral pH and potentiates its response to acidic stimulation, 37i.e. sephin1 is a novel modulator of rASIC3. Furthermore, docking experiments 38 showed that, like GMQ, guanabenz and sephin1 likely interact with the nonproton 39 ligand-sensing domain of rASIC3. Overall, these data demonstrate the utility of 40 computational analysis for identifying novel ASIC3 modulators, which can be 41 validated with electrophysiological analysis and may lead to the development of 42 better compounds for targeting ASIC3 in the treatment of inflammatory 43 conditions. 44 48 channel (ASIC) family, these voltage-independent, ligand-gated cation channels 49 are activated by extracellular protons [2][3][4] and belong to the amiloride-sensitive 50 epithelial sodium channel/degenerin (ENaC/DEG) ion channel family [5,6]. In 51 mammals, four genes (accn1-4) encode for at least 6 different ASIC subunits 52 (ASIC1a, ASIC1b, ASIC2a, ASIC2b, ASIC3, ASIC4), which can assemble into 53 homo-and heterotrimeric channels displaying different pH sensitivity, current 54 kinetics and pharmacology [7][8][9]. ASICs are widely expressed in the central and 55 peripheral nervous systems [2,10] and are implicated in a range of physiological 56 and pathological processes including nociception, mechanosensation and 57 learning/me...

Rational design of allosteric modulators: Challenges and successes

“…Acid-sensing ion channels are also expressed in CNS and are implicated in various neurological diseases such as multiple sclerosis, Parkinson's disease, and many others. 415 In a recent study focusing on identifying novel acid-sensing ion channel 3 (ASIC3) modulators, a ligand-based in silico screening of the FDA-approved drug library eDrug3D 416 using the PAM 2-guanidine-4methylquinazoline (GMQ) as a query structure was performed. 417 Using ROCS 163,273 in combination with manual inspection of the top 150 ranked hits identified five drugs as potential hits, which were validated experimentally; one drug, named GBZ, was confirmed as an ASIC3 activator.…”