Elucidation of an Allosteric Mode of Action for a Thienopyrazole RORγt Inverse Agonist

Abstract

The demand for allosteric targeting of nuclear receptors is high, but examples are limited, and structural information is scarce. The retinoic acid‐related orphan receptor gamma t (RORγt) is an important transcriptional regulator for the differentiation of T helper 17 cells for which the first, and some of the most promising, examples of allosteric nuclear receptor modulation have been reported and structurally proven. In a 2015 patent, filed by the pharmaceutical company Glenmark, a new class of small molecules was reported that act as potent inverse agonists for RORγt. A compound library around the central thienopyrazole scaffold captured a clear structure‐activity relationship, but the binding mechanism of this new class of RORγt modulators has not been elucidated. Using a combination of biochemical and X‐ray crystallography studies, here the allosteric mechanism for the inverse agonism for the most potent compound, classified in the patent as “example 13”, is reported, providing a strongly desired additional example of allosteric nuclear receptor targeting.

RORγ Structural Plasticity and Druggability

“…We compared the binding modes of nine ligands (Figure 7). Compounds 1-8 were co-crystallized with the LBD [11,[37][38][39][40]. Compound 9 was modeled from MD simulations [41].…”

“…Thus, the pocket is extendable depending on the ligand chemistry. (3) 5C4U [11]; (4) 5C4T [11]; (5) 6UCG [37]; (6) 6TLM [38]; (7) 5LWP [39]; (8) 6SAL [40]. No PDB code is available for compound (9) [41].…”

“…Allosteric inverse agonists binding in the AF-2 site. The corresponding PDB codes for the co-crystal models of the compounds binding in the RORγ LBD are listed as follows: (1) 4YPQ, 5C4O[11]; (2) 5C4S[11]; (3) 5C4U[11]; (4) 5C4T[11]; (5) 6UCG[37]; (6) 6TLM[38]; (7) 5LWP[39]; (8) 6SAL[40]. No PDB code is available for compound (9)[41].…”

RORγ Structural Plasticity and Druggability

“…We compared the binding modes of nine ligands (Figure 7). Compounds 1 -8 were cocrystallized with the LBD [11,[38][39][40][41]. Compound 9 was modeled from MD simulations [42].…”

“…Allosteric inverse agonists binding in the AF-2 site. The corresponding PDB codes for the co-crystal models of the compounds binding in the RORγ LBD are listed as follows:(1) 4YPQ, 5C4O[11]; (2) 5C4S[11]; (3) 5C4U[11]; (4) 5C4T[11]; (5) 6UCG[38]; (6) 6TLM[39]; (7) 5LWP[40]; (8) 6SAL[41]. No PDB code is available for compound 9[42].…”