Hsp90 regulates HDAC3-dependent gene transcription while HDAC3 regulates the functions of Hsp90
CELLULAR SIGNALLING
Authors: Kotwal, Akhil; Subbarao, Sreedhar Amere
Abstract
Deregulated DNA methylation and post-translational histone modifications are majorly associated with cancer progression. Histone modification regulates the gene expression patterns that contribute to the emergence of sporadic cancers. Histone deacetylases (HDACs) act as erasers of acetylation marks, and their functions are often deregulated in cancer. Since non-histone proteins can also act as substrates for HDACs, identifying their involvement in vital regulatory molecules contributing to cancer progression is essential. Hsp90 is a cancer chaperone that contributes to kinase evolution and, thus, cellular adaptations. Acetylated Hsp90 loses its chaperoning functions and client protein interactions. Robust cell proliferation is one of the hallmarks of cancer. However, Hsp90 involvement in cancer promoting gene transcription is less understood. Using human breast cancer cells, we demonstrate that nuclear Hsp90 functions are regulated by HDAC3, while Hsp90 regulates HDAC3 nuclear translocation. Pharmacological inhibition of Hsp90 decreased the HDAC3 nuclear translocation and increased the gene expression relevant to epithelial to mesenchymal transition. Further, inhibition of HDAC3 resulted in the nuclear accumulation of acetylated Hsp90. Additionally, Hsp90 inhibition affected the global histone acetylation and methylation patterns, whereas HDAC3 inhibition exhibited less impact. Our results display a novel regulatory mechanism mediated by Hsp90 and HDAC3 in tumor cells. Considering that Hsp90 and histone deacetylase inhibitors are emerging as novel anticancer agents, our findings may have clinical relevance.
Sodium Butyrate Alleviates Lipopolysaccharide-Induced Inflammatory Responses by Down-Regulation of NF-kappa B, NLRP3 Signaling Pathway, and Activating Histone Acetylation in Bovine Macrophages
FRONTIERS IN VETERINARY SCIENCE
Authors: Jiang, Liqiang; Wang, Jingjing; Liu, Ziyi; Jiang, Aimin; Li, Shuangqiu; Wu, Di; Zhang, Yong; Zhu, Xingyi; Zhou, Ershun; Wei, Zhengkai; Yang, Zhengtao
Abstract
Sodium butyrate is the sodium salt of butyric acid, which possesses many biological functions including immune system regulation, anti-oxidant and anti-inflammatory ability. The present study was designed to elucidate the anti-inflammatory effects and mechanisms of sodium butyrate on lipopolysaccharide (LPS)-stimulated bovine macrophages. The effect of sodium butyrate on the cell viability of bovine macrophages was assayed by using the CCK-8 kit. Quantitative real-time PCR (qRT-PCR) was used to detect the gene expression of interleukin-6 (IL-6), interleukin-1 beta (IL-1 beta), cyclooxygenase-2 (COX-2), and inducible Nitric Oxide Synthase (iNOS). NF-kappa B, NLRP3 signaling pathway, and histone deacetylase were detected by western blotting. The results showed that sodium butyrate had no significant effect on cell viability at 0-1 mM, and inhibited LPS-induced IL-6, IL-1 beta, COX-2, and iNOS expression. Moreover, sodium butyrate suppressed LPS (5 mu g/ml)-stimulated the phosphorylation of I kappa B and p65, inhibited the deacetylation of histone H3K9, and has also been found to inhibit protein expression in NLRP3 inflammasomes. Thus, our finding suggested that sodium butyrate relieved LPS-induced inflammatory responses in bovine macrophage by inhibiting the canonical NF-kappa B, NLRP3 signaling pathway, and histone decetylation, which might be helpful to prevent cow mastitis.