Discovery and Characterization of GSK2801, a Selective Chemical Probe for the Bromodomains BAZ2A and BAZ2B

Abstract

Bromodomains are acetyl-lysine specific protein interaction domains that have recently emerged as a new target class for the development of inhibitors that modulate gene transcription. The two closely related bromodomain containing proteins BAZ2A and BAZ2B constitute the central scaffolding protein of the nucleolar remodeling complex (NoRC) that regulates the expression of noncoding RNAs. However, BAZ2 bromodomains have low predicted druggability and so far no selective inhibitors have been published. Here we report the development of GSK2801, a potent, selective and cell active acetyl-lysine competitive inhibitor of BAZ2A and BAZ2B bromodomains as well as the inactive control compound GSK8573. GSK2801 binds to BAZ2 bromodomains with dissociation constants (KD) of 136 and 257 nM for BAZ2B and BAZ2A, respectively. Crystal structures demonstrated a canonical acetyl-lysine competitive binding mode. Cellular activity was demonstrated using fluorescent recovery after photobleaching (FRAP) monitoring displacement of GFP-BAZ2A from acetylated chromatin. A pharmacokinetic study in mice showed that GSK2801 had reasonable in vivo exposure after oral dosing, with modest clearance and reasonable plasma stability. Thus, GSK2801 represents a versatile tool compound for cellular and in vivo studies to understand the role of BAZ2 bromodomains in chromatin biology.

Stereoselective Synthesis of Tetrahydroindolizines through the Catalytic Formation of Pyridinium Ylides from Diazo Compounds

“…Diazophenylacetic acid-derived pyridine 19 did not undergo cyclization with oxindole 1 using catalytic Fe(TPP)Cl in toluene (Scheme 7). More effective reaction was obtained using 5 mol% of (MeCN) 4 CuPF 6 pre-catalyst in CH 2 Cl 2 , which previously returned high yields of product 2 (Scheme 3), leading to a 57% yield of cycloadduct 20. Cycloadduct 21 was obtained in 70% yield following reaction with Nmethylmaleimide.…”

“…[2,3] Both structures are valued for their therapeutic potential. [4][5][6] Spirooxindoles have also been identified as privileged scaffolds for drug discovery. [7] Efficient and versatile routes toward these structural motifs are highly desirable therefore.…”

“…Satisfyingly, tetrahydroindolizidine 2 was obtained as the sole product in good yield (89-90%) as a single diastereoisomer when either 5 mol% of Fe(TPP)Cl or (MeCN) 4 CuPF 6 were used. The NMR data of 2 suggested that the sense of diastereoselectivity was the same as related products prepared by conventional base-promoted ylide formation.…”

“…The NMR data of 2 suggested that the sense of diastereoselectivity was the same as related products prepared by conventional base-promoted ylide formation. [24] Cyclopropane 3 was obtained as the only product when Rh 2 (OAc) 4 (1 mol%) was used as the catalyst, however. A catalyst loading of 1 mol% of Fe(TPP)Cl in toluene led to similar yields of 2 (89%), so these conditions were used.…”

Bromodomains in Protozoan Parasites: Evolution, Function, and Opportunities for Drug Development

“…The two closely related bromodomain-adjacent zinc finger (BAZ) bromodomain proteins BAZ2A and BAZ2B play essential regulatory roles in chromatin remodeling and have also been implicated in the regulation of noncoding RNAs (41,42). Two independent attempts at structure-based compound optimization based on two initially weak inhibitors led to development of GSK2801 and BAZ2-ICR, selectively potent inhibitors of both BAZ2A and BAZ2B (43,44).…”