Abstract A19: A novel MECP2 acetylation site regulates binding with ATRX and HDAC1

Abstract

Tumorigenesis stems from errors incorporated in the genetic code and impaired epigenetic mechanisms involved in tumor suppression. Mutation in methyl-CpG-binding protein 2 (MeCP2) is known to cause a neurological disorder, rett syndrome (RTT), however its role in tumorigenesis remains poorly understood. We wanted to characterize how novel post-translational modifications might contribute to its function. MeCP2 regulates gene expression by recruiting co-repressors and histone deacetylases (such as HDAC1) to methylated gene promoters. MeCP2 modulates heterochromatin association by interacting with heterochromatin protein 1 (HP1). It was shown that MeCP2 interacts with and recruits ATRX, a SWI2/SNF2 DNA helicase/ATPase, to regulate gene expression at a subset of imprinted domains. A recent study showed that overexpression of Sirtuin1 (SIRT1) deacetylase leads to reduced levels of acetylation of ectopically expressed MeCP2. Using mass spectrometry, we report that upon pharmacological inhibition of SIRT1 in colon and breast cancer cell lines, endogenous MeCP2 is acetylated at key sites known to be critical for binding to DNA and transcriptional regulators. We mapped several novel acetylated sites and then created an acetylation mimetic mutation in MeCP2 (K171Q) and found that this mutant shows decreased binding to HDAC1 and ATRX in RKO cells. Similar results were obtained when SIRT1 was pharmacologically inhibited. Herein we show that conditions that induce MeCP2 acetylation in RKO cells do not alter its promoter occupancy at a subset of target genes analyzed but do cause a decreased binding to co-repressors such as HDAC1 and ATRX and also alters ATRX binding at a specific gene promoter. We also demonstrate that RKO cells over-expressing our acetylation mimetic mutant show reduced proliferation as compared to those over-expressing MeCP2-wild type (WT). Citation Format: Somnath Pandey, Glenn E. Simmons Jr., Svitlana Malyarchuk, Tara N. Calhoun, Kevin Pruitt. A novel MECP2 acetylation site regulates binding with ATRX and HDAC1. [abstract]. In: Proceedings of the AACR Special Conference on Chromatin and Epigenetics in Cancer; Sep 24-27, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2016;76(2 Suppl):Abstract nr A19.

Epigenomic changes associated with impaired norepinephrine transporter function in postural tachycardia syndrome

“…The CpG sites that correlate with these physiological measures correspond with the 376 binding sites for the transcription factors such as Sp1and serum response factor (SRF). The The region 2 (-515bp to -215bp) was hypomethylated with the methylation percentage shown in 387 protein partners ATRX and HDAC1 (Pandey et al, 2015). It is possible that differential PTM of 500…”

DNA methylation in fibrosis

“…MeCP2 is able to bind to a single methylated CpG dinucleotide and shows weaker binding to methylated non-CpG sequences; MeCP2 binding to methylated CpGs can result in gene repression, however, its suppressive capabilities rely on HDAC1 (Nan et al, 1998). MeCP2 recruits HDAC1 to methylated DNA where it regulates heterochromatic association through interaction with a protein responsible for heterochromatic packaging, Heterochromatin protein-1 (Pandey et al, 2015). Hemi-methylated DNA has been shown to be a poor substrate for MeCP2, meaning there will be less repression (Meehan et al, 1992).…”