Sodium valproate is effective against Botrytis cinerea infection of tomato by enhancing histone H3 acetylation-directed gene transcription and triggering tomato fruits immune response

Botrytis cinerea causes grey mold resulting in enormous financial loss. Fungicide resistance of B. cinerea has become a serious issue in food safety and agricultural environmental protection. Sodium valproate (SV) has been used in clinical trials, thus it is excellent candidate for fungicide development considering its safety. However, the antifungal activity remains unclear. SV was effective against B. cinerea by enhancing acetylation of histone H3, including H3K9ac, H3K14ac, and H3K56ac. A transcriptomics analysis revealed that the expression of 1,557 genes changed significantly in response to SV. A pathway enrichment analysis identified 16 significant GO terms, in which molecular functions were mainly involved. In addition, the expression levels of 13 genes involved in B. cinerea virulence and 5 genes involved in tomato immune response were altered by the SV treatment. These results indicate that SV inhibits B. cinerea by enhancing acetylation of histone H3 and modifying gene transcription. Thus, SV is an effective, safe potential antifungal agent for control of both pre- and post-harvest losses caused by B. cinerea.

Chiffon triggers global histone H3 acetylation and expression of developmental genes in Drosophila embryos

The histone acetyltransferase Gcn5 is critical for gene expression and development. In Drosophila, Gcn5 is part of four complexes (SAGA, ATAC, CHAT, and ADA) that are essential for fly viability and have key roles in regulating gene expression. Here, we show that while the SAGA, ADA, and CHAT complexes play redundant roles in embryonic gene expression, the insect-specific CHAT complex uniquely regulates expression of a subset of developmental genes. We also identify a substantial decrease in histone acetylation in chiffon mutant embryos that exceeds that observed in ada2b, suggesting broader roles for Chiffon in regulating histone acetylation outside of the Gcn5 complexes. The chiffon gene encodes two independent polypeptides that nucleate formation of either the CHAT or Dbf4-dependent kinase (DDK) complexes. DDK includes the cell cycle kinase Cdc7, which is necessary for maternally-driven DNA replication in the embryo. We identify a temporal switch between the expression of these chiffon gene products during a short window during the early nuclear cycles in embryos that correlates with the onset of zygotic genome activation, suggesting a potential role for CHAT in this process.

Inhibition of class I HDACs preserves hair follicle inductivity in postnatal dermal cells

Induction of new hair follicles (HFs) may be an ultimate treatment goal for alopecia; however, functional cells with HF inductivity must be expanded in bulk for clinical use. In vitro culture conditions are completely different from the in vivo microenvironment. Although fetal and postnatal dermal cells (DCs) have the potential to induce HFs, they rapidly lose this HF inductivity during culture, accompanied by a drastic change in gene expression. This suggests that epigenetic regulation may be involved. Of the various histone deacetylases (HDACs), Class I HDACs are noteworthy because they are ubiquitously expressed and have the strongest deacetylase activity. This study revealed that DCs from postnatal mice rapidly lose HF inductivity and that this reduction is accompanied by a significant decrease in histone H3 acetylation. However, MS-275, an inhibitor of class I HDACs, preserves HF inductivity in DCs during culture, increasing alkaline phosphatase activity and upregulating HF inductive genes such as BMP4, HEY1, and WIF1. In addition, the inhibition of class I HDACs activates the Wnt signaling pathway, the most well-described molecular pathway in HF development, via increased histone H3 acetylation within the promoter region of the Wnt transcription factor LEF1. Our results suggest that class I HDACs could be a potential target for the neogenesis of HFs.

PER2 mediates CREB-dependent light induction of the clock gene Per1

Light affects many physiological processes in mammals such as entrainment of the circadian clock, regulation of mood, and relaxation of blood vessels. At the molecular level, a stimulus such as light initiates a cascade of kinases that phosphorylate CREB at various sites, including serine 133 (S133). This modification leads CREB to recruit the co-factor CRCT1 and the histone acetyltransferase CBP to stimulate the transcription of genes containing a CRE element in their promoters, such as Period 1 (Per1). However, the details of this pathway are poorly understood. Here we provide evidence that PER2 acts as a co-factor of CREB to facilitate the formation of a transactivation complex on the CRE element of the Per1 gene regulatory region in response to light or forskolin. Using in vitro and in vivo approaches, we show that PER2 modulates the interaction between CREB and its co-regulator CRTC1 to support complex formation only after a light or forskolin stimulus. Furthermore, the absence of PER2 abolished the interaction between the histone acetyltransferase CBP and CREB. This process was accompanied by a reduction of histone H3 acetylation and decreased recruitment of RNA Pol II to the Per1 gene. Collectively, our data show that PER2 supports the stimulus-dependent induction of the Per1 gene via modulation of the CREB/CRTC1/CBP complex.

Arabidopsis SUMO E3 Ligase SIZ1 Interacts with HDA6 and Negatively Regulates HDA6 Function during Flowering

The changes in histone acetylation mediated by histone deacetylases (HDAC) play a crucial role in plant development and response to environmental changes. Mammalian HDACs are regulated by post-translational modifications (PTM), such as phosphorylation, acetylation, ubiquitination and small ubiquitin-like modifier (SUMO) modification (SUMOylation), which affect enzymatic activity and transcriptional repression. Whether PTMs of plant HDACs alter their functions are largely unknown. In this study, we demonstrated that the Arabidopsis SUMO E3 ligase SAP AND MIZ1 DOMAIN-CONTAINING LIGASE1 (SIZ1) interacts with HISTONE DEACETYLASE 6 (HDA6) both in vitro and in vivo. Biochemical analyses indicated that HDA6 is not modified by SUMO1. Overexpression of HDA6 in siz1-3 background results in a decreased level of histone H3 acetylation, indicating that the activity of HDA6 is increased in siz1-3 plants. Chromatin immunoprecipitation (ChIP) assays showed that SIZ1 represses HDA6 binding to its target genes FLOWERING LOCUS C (FLC) and MADS AFFECTING FLOWERING 4 (MAF4), resulting in the upregulation of FLC and MAF4 by increasing the level of histone H3 acetylation. Together, these findings indicate that the Arabidopsis SUMO E3 ligase SIZ1 interacts with HDA6 and negatively regulates HDA6 function.

An E2F5-TFDP1-BRG1 Complex Mediates Transcriptional Activation of MYCN in Hepatocytes

Liver regeneration is characterized by cell cycle reentrance of hepatocytes. N-Myc, encoded by MYCN, is a member of the Myc family of transcription factors. Elevation of MYCN expression has been noted in the course of liver regeneration whereas the underlying mechanism remains unclear. Here we describe that up-regulation of MYCN expression, as measured by quantitative PCR, Western blotting, and immunohistochemical staining, paralleled liver regeneration in animal and cell models. MYCN expression was up-regulated as a result of transcriptional activation. Ingenuity pathway analysis (IPA) revealed several up-stream transcriptional regulators for MYCN and RNA interference validated E2F5 and TFDP1 as essential for hepatocyte growth factor (HGF)-induced MYCN trans-activation. Further examination showed that deficiency of BRG1, a chromatin remodeling protein, attenuated MYCN induction during liver regeneration. BRG1 interacted with and was recruited by E2F5/TFDP1 to the MYCN promoter. Mechanistically, BRG1 might play a role regulating histone H3 acetylation and H3K4 trimethylation and facilitating/stabilizing the binding of RNA polymerase II surrounding the MYCN promoter. Over-expression of ectopic MYCN in BRG1-null hepatocytes overcame deficiency of proliferation. Importantly, a positive correlation between MYCN expression and BRG1/E2F5/TFDP1 expression was observed in human liver specimens. In conclusion, our data identify a novel epigenetic pathway where an E2F5-TFDP1-BRG1 complex regulates MYCN transcription to promote liver regeneration.

Inactivation of the CIC-DUX4 oncogene through P300/CBP inhibition, a therapeutic approach for CIC-DUX4 sarcoma

CIC-DUX4 sarcoma (CDS) is a highly aggressive and metastatic small round type of predominantly pediatric sarcoma driven by a fusion oncoprotein comprising the transcriptional repressor Capicua (CIC) fused to the C-terminal transcriptional activation domain of DUX4. CDS rapidly develops resistance to chemotherapy, thus novel specific therapies are greatly needed. We demonstrate that CIC-DUX4 requires P300/CBP to induce histone H3 acetylation, activate its targets, and drive oncogenesis. We describe the synthetic route to a selective and highly potent P300/CBP inhibitor named iP300w and related stereoisomers, and find that iP300w efficiently suppresses CIC-DUX4 transcriptional activity and reverses CIC-DUX4 induced acetylation. iP300w is active at 100-fold lower concentrations than related stereoisomers or A-485. At low doses, iP300w shows specificity to CDS cancer cell lines, rapidly inducing cell cycle arrest and preventing growth of established CDS xenograft tumors when delivered in vivo. The effectiveness of iP300w to inactivate CIC-DUX4 highlights a promising therapeutic opportunity for CDS.