Discovery of ML314, a Brain Penetrant Nonpeptidic β-Arrestin Biased Agonist of the Neurotensin NTR1 Receptor

Abstract

The neurotensin 1 receptor (NTR1) is an important therapeutic target for a range of disease states including addiction. A high throughput screening campaign, followed by medicinal chemistry optimization, led to the discovery of a non-peptidic β-arrestin biased agonist for NTR1. The lead compound, 2-cyclopropyl-6,7-dimethoxy-4-(4-(2-methoxyphenyl)- piperazin-1-yl)quinazoline, 32 (ML314), exhibits full agonist behavior against NTR1 (EC50 = 2.0 μM) in the primary assay and selectivity against NTR2. The effect of 32 is blocked by the NTR1 antagonist SR142948A in a dose dependent manner. Unlike peptide based NTR1 agonists, compound 32 has no significant response in a Ca2+ mobilization assay and is thus a biased agonist that activates the β-arrestin pathway rather than the traditional Gq coupled pathway. This bias has distinct biochemical and functional consequences that may lead to physiological advantages. Compound 32 displays good brain penetration in rodents, and studies examining its in vivo properties are underway.

ML314: A Biased Neurotensin Receptor Ligand for Methamphetamine Abuse

“…3A, middle panels). Supporting the finding that the ML314 response is mediated through the NTR1 are competition experiments in which the antagonist SR142948A blocks β-arrestin aggregate formation for the neurotensin peptide NT(8-13) 35 , and at similar potency for micromolar concentrations of ML314 35 , and the related small molecule agonist ML301 (fig. 3B left) that was also synthesized for this project 34 .…”

“…3B left) that was also synthesized for this project 34 . We have observed using an aequorin calcium reporter and a ratiometric calcium assay that ML314 is unable to activate calcium through the NTR1 32, 35 . Binding of ML314 to either an allosteric or overlapping orthosteric receptor site 41 , however, might perturb NTR1-mediated Gq signaling (fig.…”

“…Competitive assessment of β-arrestin2 translocation to the NTR1 using the antagonist SR142948A in U2OS cells (left). The cells were pre-treated with the neurotensin receptor antagonist SR142948A for 10 minutes as described 35 , followed by the addition of 10 μM ML301 for 40 minutes and paraformaldehyde fixation. The number of cytoplasmic aggregated objects was determined using Waveprog 32 .…”

G Protein and β-Arrestin Signaling Bias at the Ghrelin Receptor

“…The G q/11 -coupled neurotensin receptor 1 (NTR1) is closely related to GHSR1a. Recently, a ␤-arrestin-biased ligand, ML314, was identified for NTR1, utilizing a ␤-arrestin translocation assay in a high throughput screen (56,57). This brain penetrant small mole-FIGURE 10.…”

The discovery of indole full agonists of the neurotensin receptor 1 (NTSR1)

“…Conversely, only a small number of non-peptide positive and negative modulators of the NTRS1 have been discovered to date (Figure 1). These include the partial agonist 1 reported by researchers at Wyeth, 22 the pyrazole-derived agonist 2 , 23 the β -arrestin biased brain penetrant agonist ML314 ( 3 ) 24 and the recently discovered positive modulator ML301 ( 4 ). 25 Among NTSR1 antagonists, stand out two trisubstituted pyrazole derivatives structurally related to agonists 2 and 4 : SR 48692 ( 5 ) 26 and SR 142948A ( 6 ), 27 which show binding affinities in the low nanomolar range.…”