GAS41 promotes H2A.Z deposition through recognition of the N terminus of histone H3 by the YEATS domain.

Glioma amplified sequence 41 (GAS41), which has the Yaf9, ENL, AF9, Taf14, and Sas5 (YEATS) domain that recognizes lysine acetylation (Kac), regulates gene expression as a subunit of the SRCAP (SNF2-related CREBBP activator protein) complex that deposits histone H2A.Z at promoters in eukaryotes. The YEATS domains of the proteins AF9 and ENL recognize Kac by hydrogen bonding the aromatic cage to arginine situated just before K9ac or K27ac in the N-terminal tail of histone H3. Curiously, the YEATS domain of GAS41 binds most preferentially to the sequence that contains K14ac of H3 (H3K14ac) but lacks the corresponding arginine. Here, we biochemically and structurally elucidated the molecular mechanism by which GAS41 recognizes H3K14ac. First, stable binding of the GAS41 YEATS domain to H3K14ac required the N terminus of H3 (H3NT). Second, we revealed a pocket in the GAS41 YEATS domain responsible for the H3NT binding by crystallographic and NMR analyses. This pocket is away from the aromatic cage that recognizes Kac and is unique to GAS41 among the YEATS family. Finally, we showed that E109 of GAS41, a residue essential for the formation of the H3NT-binding pocket, was crucial for chromatin occupancy of H2A.Z and GAS41 at H2A.Z-enriched promoter regions. These data suggest that binding of GAS41 to H3NT via its YEATS domain is essential for its intracellular function.

Identification of a derivative of the alkaloid emetine as an inhibitor of the YAP-TEAD interaction and its potential as an anticancer agent.

TEAD is a transcription factor responsible for the output of the tumor suppressor Hippo pathway. The transcriptional activity of TEAD requires molecular interaction with its transcriptional coactivator, YAP. Aberrant activation of TEAD is deeply involved in tumorigenesis and is associated with poor prognosis, suggesting that inhibitors targeting the YAP-TEAD system are promising as antitumor agents. In this study, we identified NPD689, an analog of the natural product alkaloid emetine, as an inhibitor of the YAP-TEAD interaction. NPD689 suppressed the transcriptional activity of TEAD and reduced the viability of human malignant pleural mesothelioma and non-small cell lung cancer cells but not the viability of normal human mesothelial cells. Our results suggest that NPD689 is not only a new useful chemical tool for elucidating the biological role of the YAP-TEAD system but also has potential as a starting compound for developing a cancer therapeutic agent that targets the YAP-TEAD interaction.

17ß-neriifolin from unripe fruits of Cerbera manghas suppressed cell proliferation via the inhibition of HOXA9-dependent transcription and the induction of apoptosis in the human AML cell line THP-1.

Homeobox A9 (HOXA9) is a transcription factor that is overexpressed in acute myeloid leukemia (AML). It is associated with the pathogenesis and progression of AML, and is a factor responsible for a poor prognosis. Therefore, the development of HOXA9-targeting molecules may contribute to not only better understanding of the mechanism of HOXA9 regulation, but also the development of therapeutic applications. We constructed a reporter assay system using the promoter region of the KBTBD10 gene, to which HOXA9 directly binds and regulates transcription, in the human acute monocytic leukemia cell line THP-1. Using this luciferase gene assay, we screened 1120 plant extracts and a methanol extract of the unripe fruits of Cerbera manghas was found to suppress the reporter gene expression mediated by the KBTBD10 promoter. From the extract, five steroid-type compounds were identified as the active constituents: 7α-neriifolin (1), 17ß-neriifolin (2), 17α-digitoxigenin ß-D-glucosyl-(1 → 4)-α-L-thevetoside (3), 17ß-digitoxigenin ß-D-glucosyl-(1 → 4)-α-L-thevetoside (4), and acetylthevetin B (5). Among the five compounds, 17ß-neriifolin most potently inhibited HOXA9-dependent gene expression without affecting the HOXA9 mRNA levels, and suppressed cell proliferation by inducing apoptosis. The findings on the structure-activity relationships of the compounds from C. manghas may contribute to the development of small molecule inhibitors of HOXA9.