G9a Inhibition Promotes Neuroprotection through GMFB Regulation in Alzheimer’s Disease

Epigenetic alterations are a fundamental pathological hallmark of Alzheimer’s disease (AD). Herein, we show the upregulation of G9a and H3K9me2 in the brains of AD patients. Interestingly, treatment with a G9a inhibitor (G9ai) in SAMP8 mice reversed the high levels of H3K9me2 and rescued cognitive decline. A transcriptional profile analysis after G9ai treatment revealed increased gene expression of glia maturation factor β (GMFB) in SAMP8 mice. Besides, a H3K9me2 ChIP-seq analysis after G9a inhibition treatment showed the enrichment of gene promoters associated with neural functions. We observed the induction of neuronal plasticity and a reduction of neuroinflammation after G9ai treatment, and more strikingly, these neuroprotective effects were reverted by the pharmacological inhibition of GMFB in mice and cell cultures; this was also validated by the RNAi approach generating the knockdown of GMFB/Y507A.10 in Caenorhabditis elegans. Importantly, we present evidence that GMFB activity is controlled by G9a-mediated lysine methylation as well as we identified that G9a directly bound GMFB and catalyzed the methylation at lysine (K) 20 and K25 in vitro. Furthermore, we found that the neurodegenerative role of G9a as a GMFB suppressor would mainly rely on methylation of the K25 position of GMFB, and thus G9a pharmacological inhibition removes this methylation promoting neuroprotective effects. Then, our findings confirm an undescribed mechanism by which G9a inhibition acts at two levels, increasing GMFB and regulating its function to promote neuroprotective effects in age-related cognitive decline</p

Thirty years of molecular dynamics simulations on posttranslational modifications of proteins

Posttranslational modifications (PTMs) are an integral component to how cells respond to perturbation. While experimental advances have enabled improved PTM identification capabilities, the same throughput for characterizing how structural changes caused by PTMs equate to altered physiological function has not been maintained. In this Perspective, we cover the history of computational modeling and molecular dynamics simulations which have characterized the structural implications of PTMs. We distinguish results from different molecular dynamics studies based upon the timescales simulated and analysis approaches used for PTM characterization. Lastly, we offer insights into how opportunities for modern research efforts on in silico PTM characterization may proceed given current state-of-the-art computing capabilities and methodological advancements.Comment: 64 pages, 11 figure

Role of PRMT5 in ULK1-Mediated Autophagy and Breast Cancer Therapy

PRMT5 (Protein arginine methyltransferase 5) is the predominant type II PRMT that monomethylates and symmetrically dimethylates arginine residues of histone and none- histone proteins to regulate diverse cellular processes. PRMT5 overexpression has been implicated in tumorigenesis and other diseases and has gained trac1on as a poten1al an1tumor target with some of its inhibitors being tested in clinical trials. Despite the well- established an1tumor effect of PRMT5 inhibitors, how the efficacy of these inhibitors is regulated is unexplored. We show in this study that autophagy blockage enhances cellular sensi1vity to PRMT5 inhibitor in triple nega1ve breast cancer cells. Both gene1c deple1on and pharmacological inhibi1on of PRMT5 evoke cytoprotec1ve autophagy. We further establish that PRMT5 suppresses basal autophagy across different breast cancer types. Mechanis1cally, PRMT5 catalyzes monomethyla1on of ULK1 at R532 to suppress its autophagic func1ons. As a result, ULK1 inhibi1on or dele1on blocks PRMT5 deficiency- induced autophagy and sensi1zes cells to PRMT5 inhibitor. Our study iden1fies inducible autophagy as an important determinant of cellular sensi1vity to PRMT5 inhibitor, and also establishes ULK1 as a bonafide substrate of PRMT5 in the autophagy, providing a ra1onale for combining PRMT5 and autophagy inhibitors in cancer therapy