Search

Members of the basic helix-loop-helix (bHLH) transcription factor family play an essential role in multiple developmental processes. During neurogenesis, positive and negative regulation by bHLH proteins is essential for proper development. Here we report the identification and initial characterization of the bHLH gene, Neuronal twist (N-twist), named for its neural expression pattern and high sequence homology and physical linkage to the mesodermal inhibitor, M-twist. N-twist is expressed in the developing mouse central nervous system in the midbrain, hindbrain, and neural tube. This neural expression is conserved in invertebrates, as expression of the Drosophila ortholog of N-twist is also restricted to the central nervous system. Like other bHLH family members, N-Twist heterodimerizes with E protein and binds DNA at a consensus bHLH-binding site, the E box. We show that N-Twist inhibits MASH1-dependent transcriptional activation by sequestering E protein in a dominant negative fashion. Thus, these studies support the notion that N-Twist represents a novel negative regulator of neurogenesis. Key Words: N-twist; basic-helix-loop-helix; bHLH; achaete-scute; neurogenesis; MASH1; inhibitor; transcription; brain; neural tube; mouse; Drosophila.

Sustained androgen receptor (AR) signaling during relapse is a central driver of metastatic castration-resistant prostate cancer (mCRPC). Current AR antagonists, such as enzalutamide, fail to provide long-term benefit for the mCRPC patients who have dramatic increases in AR expression. Here, we report AR antagonists with efficacy in AR-overexpressing models. These molecules bind to the ligand-binding domain of the AR, promote AR localization to the nucleus, yet potently and selectively down-regulate AR-target genes. The molecules BG-15a and the pharmacokinetically optimized BG-15n elicit a decrease in cell and tumor growth in vitro and in vivo in models of mCRPC. BG-15a/n treatment causes the collapse of chromatin loops between enhancers and promoters at key genes in the AR-driven epigenome. AR binding in the promoter, as well as 3D chromatin clustering, is needed for genes to respond. BG-15a/n represent promising agents for treating patients with relapsed AR-driven mCRPC tumors., Competing Interests: Competing interests statement:E.C. received research funding under institutional SRA from Janssen Research and Development, Bayer Pharmaceuticals, KronosBio, Forma Pharmaceutics Foghorn, Gilead, Sanofi, AbbVie, MacrogGenics, Astra Zeneca, GSK, and K36. B.E.G., A.K.O., S.T., W.D.F., and J.S. are co-inventors on a patent covering this technology (WO2021150603A1). P.S.N. receives personal fees from Janssen, Bristol Myers Squibb, Pfizer, and Merck and grants from Janssen. The other authors declare no competing interests.