LY2119620

LY2119620 is a selective positive allosteric modulator of M2/M4 receptor [1].

Muscarinic acetylcholine receptors (M1-M5) are G-protein coupled receptors regulating the action of the neurotransmitter ACh and play an important role in smooth muscle control, exocrine gland function, mood and cognition [1].

LY2119620 is a selective positive allosteric modulator of M2/M4 receptor. In [35S]GTPγS-binding experiments, LY2119620 exhibited a modest allosteric agonism of 23.2% and 16.8% at the M2 and M4 receptors, respectively. LY2119620 and ACh binding caused cooperativity factor α of 79.4 and 19.5 for the M4 receptor and the M2 receptor, respectively. The cooperativity between LY2119620 and orthosteric agonists (Iperoxo or Oxo-M) was also observed [1]. M2 receptor simultaneously bound to LY2119620 and iperoxo. LY2119620 exhibited mild negative cooperativity with the inverse agonist NMS and strong positive cooperativity with iperoxo [2]. LY2119620 significantly increased Bmax values without changes in Kd when cooperativity binding of [3H]LY2119620 with mAChR, suggesting a G protein-dependent process [3].

References:
[1].  Croy CH, Schober DA, Xiao H, et al. Characterization of the novel positive allosteric modulator, LY2119620, at the muscarinic M(2) and M(4) receptors. Mol Pharmacol, 2014, 86(1): 106-115.
Kruse AC, Ring AM, Manglik A, et al.  Activation and allosteric modulation of a muscarinic acetylcholine receptor. Nature, 2013, 504(7478): 101-106.
Schober DA, Croy CH, Xiao H, et al.  Development of a radioligand, [(3)H]LY2119620, to probe the human M(2) and M(4) muscarinic receptor allosteric binding sites. Mol Pharmacol, 2014, 86(1): 116-123.

Development of a radioligand, [(3)H]LY2119620, to probe the human M(2) and M(4) muscarinic receptor allosteric binding sites.[Pubmed:24807966]

Mol Pharmacol. 2014 Jul;86(1):116-23.

In this study, we characterized a muscarinic acetylcholine receptor (mAChR) potentiator, LY2119620 (3-amino-5-chloro-N-cyclopropyl-4-methyl-6-[2-(4-methylpiperazin-1-yl)-2-oxoethox y]thieno[2,3-b]pyridine-2-carboxamide) as a novel probe of the human M2 and M4 allosteric binding sites. Since the discovery of allosteric binding sites on G protein-coupled receptors, compounds targeting these novel sites have been starting to emerge. For example, LY2033298 (3-amino-5-chloro-6-methoxy-4-methyl-thieno(2,3-b)pyridine-2-carboxylic acid cyclopropylamid) and a derivative of this chemical scaffold, VU152100 (3-amino-N-(4-methoxybenzyl)-4,6-dimethylthieno[2,3-b]pyridine carboxamide), bind to the human M4 mAChR allosteric pocket. In the current study, we characterized LY2119620, a compound similar in structure to LY2033298 and binds to the same allosteric site on the human M4 mAChRs. However, LY2119620 also binds to an allosteric site on the human M2 subtype. [(3)H]NMS ([(3)H]N-methylscopolamine) binding experiments confirm that LY2119620 does not compete for the orthosteric binding pocket at any of the five muscarinic receptor subtypes. Dissociation kinetic studies using [(3)H]NMS further support that LY2119620 binds allosterically to the M2 and M4 mAChRs and was positively cooperative with muscarinic orthosteric agonists. To probe directly the allosteric sites on M2 and M4, we radiolabeled LY2119620. Cooperativity binding of [(3)H]LY2119620 with mAChR orthosteric agonists detects significant changes in Bmax values with little change in Kd, suggesting a G protein-dependent process. Furthermore, [(3)H]LY2119620 was displaced by compounds of similar chemical structure but not by previously described mAChR allosteric compounds such as gallamine or WIN 62,577 (17-beta-hydroxy-17-alpha-ethynyl-delta-4-androstano[3,2-b]pyrimido[1,2-a]benzimi dazole). Our results therefore demonstrate the development of a radioligand, [(3)H]LY2119620 to probe specifically the human M2 and M4 muscarinic receptor allosteric binding sites.

Characterization of the novel positive allosteric modulator, LY2119620, at the muscarinic M(2) and M(4) receptors.[Pubmed:24807965]

Mol Pharmacol. 2014 Jul;86(1):106-15.

The M(4) receptor is a compelling therapeutic target, as this receptor modulates neural circuits dysregulated in schizophrenia, and there is clinical evidence that muscarinic agonists possess both antipsychotic and procognitive efficacy. Recent efforts have shifted toward allosteric ligands to maximize receptor selectivity and manipulate endogenous cholinergic and dopaminergic signaling. In this study, we present the pharmacological characterization of LY2119620 (3-amino-5-chloro-N-cyclopropyl-4-methyl-6-[2-(4-methylpiperazin-1-yl)-2-oxoethox y] thieno[2,3-b]pyridine-2-carboxamide), a M(2)/M(4) receptor-selective positive allosteric modulator (PAM), chemically evolved from hits identified through a M4 allosteric functional screen. Although unsuitable as a therapeutic due to M(2) receptor cross-reactivity and, thus, potential cardiovascular liability, LY2119620 surpassed previous congeners in potency and PAM activity and broadens research capabilities through its development into a radiotracer. Characterization of LY2119620 revealed evidence of probe dependence in both binding and functional assays. Guanosine 5'-[gamma-(35)S]-triphosphate assays displayed differential potentiation depending on the orthosteric-allosteric pairing, with the largest cooperativity observed for oxotremorine M (Oxo-M) LY2119620. Further [(3)H]Oxo-M saturation binding, including studies with guanosine-5'-[(beta,gamma)-imido]triphosphate, suggests that both the orthosteric and allosteric ligands can alter the population of receptors in the active G protein-coupled state. Additionally, this work expands the characterization of the orthosteric agonist, iperoxo, at the M(4) receptor, and demonstrates that an allosteric ligand can positively modulate the binding and functional efficacy of this high efficacy ligand. Ultimately, it was the M(2) receptor pharmacology and PAM activity with iperoxo that made LY2119620 the most suitable allosteric partner for the M(2) active-state structure recently solved (Kruse et al., 2013), a structure that provides crucial insights into the mechanisms of orthosteric activation and allosteric modulation of muscarinic receptors.