BMS 753

Ki : 2 nM for RARα

Three retinoic acid receptors (RARα, RARβ and RARγ and three retinoid X receptors, members of the nuclear receptor (NR) superfamily, mediate the biological effects of retinoic acids (all-tratis and 9-cis retinoic acids; t-RA and 9c-RA) upon development, cell differentiation and proliferation, and homeostasis. BMS 753 is identified as a RARα-selective agonist.

In vitro: Increasing concentrations of BMS 753 resulted in low levels of RARβ2 transcripts in WT cells, even at the highest concentration, while 100 nM BMS 753 efficiently induced RARβ2 transcripts in RARγ-/- cells. In contrast, no activation was seen in RARα-/- cells up to 100 nM BMS 753, demonstrating that it is specific for RARα [1].

In vivo: To investigate whether similar RARα-dependent events in Sertoli cells (SC) also operate in the reinitiation of spermatogenesis in a vitamin A-deficient (VAD) testis, Rbp4-null adult males fed a VAD diet for 14 wk were treated with BMS 753 or with its vehicle only. Interestingly, spermatogenesis did not initiate upon administration of BMS 753 to VAD Rbp4-null mutants; only SC and spermatogonia were present in their seminiferous epithelium, as in the vehicle-treated situation [2].

Clinical trial: Up to now, BMS 753 is still in the preclinical development stage.

Reference:
[1] RESHMA TANEJA, BIDYUT ROY, JEAN-Luc PLASSAT, CHRIS F.  ZuSIt, JACEK OSTROWSKIS, PETER R. RECZEKS, AND PIERRE CHAMBON. Cell-type and promoter-context dependent retinoic acid receptor (RAR) redundancies for RARβ2 and Hoxa-1 activation in F9 and P19 cells can be artefactually generated by gene knockouts. Proc. Natl. Acad. Sci. USA Vol. 93, pp. 6197-6202, June 1996.
[2] Raverdeau M, Gely-Pernot A, Féret B, Dennefeld C, Benoit G, Davidson I, Chambon P, Mark M, Ghyselinck NB.  Retinoic acid induces Sertoli cell paracrine signals for spermatogonia differentiation but cell autonomously drives spermatocyte meiosis. Proc Natl Acad Sci U S A. 2012 Oct 9;109(41):16582-7.

Structural basis for engineering of retinoic acid receptor isotype-selective agonists and antagonists.[Pubmed:10421757]

Chem Biol. 1999 Aug;6(8):519-29.

BACKGROUND: Many synthetic retinoids have been generated that exhibit a distinct pattern of agonist/antagonist activities with the three retinoic acid receptors (RARalpha, RARbeta and RARgamma). Because these retinoids are selective tools with which to dissect the pleiotropic functions of the natural pan-agonist, retinoic acid, and might constitute new therapeutic drugs, we have determined the structural basis of their receptor specificity and compared their activities in animal and yeast cells. RESULTS: There are only three divergent amino acid residues in the ligand binding pockets (LBPs) of RARalpha, RARbeta and RARgamma. We demonstrate here that the ability of monospecific (class I) retinoid agonists and antagonists to bind to and induce or inhibit transactivation by a given isotype is directly linked to the nature of these residues. The agonist/antagonist potential of class II retinoids, which bind to all three RARs but depending on the RAR isotype have the potential to act as agonists or antagonists, was also largely determined by the three divergent LBP residues. These mutational studies were complemented by modelling, on the basis of the three-dimensional structures of the RAR ligand-binding domains, and a comparison of the retinoid agonist/antagonist activities in animal and yeast cells. CONCLUSIONS: Our results reveal the rational basis of RAR isotype selectivity, explain the existence of class I and II retinoids, and provide a structural concept of ligand-mediated antagonism. Interestingly, the agonist/antagonist characteristics of retinoids are not conserved in yeast cells, suggesting that yeast co-regulators interact with RARs in a different way than the animal cell homologues do.