Browsing by Subject "Acetylation"

Now showing 1 - 10 of 26
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    Acetylation rates and bile acids side chain shielding
    (1966) Sattar, Amira Jabbar
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    Altered Smooth Muscle Cell Histone Acetylome by the SPHK2/S1P Axis Promotes Pulmonary Hypertension
    (American Heart Association, 2023) Ranasinghe, A. Dushani C. U.; Holohan, Maggie; Borger, Kalyn M.; Donahue, Deborah L.; Kuc, Rafael D.; Gerig, Martin; Kim, Andrew; Ploplis, Victoria A.; Castellino, Francis J.; Schwarz, Margaret A.; Pediatrics, School of Medicine
    Background: Epigenetic regulation of vascular remodeling in pulmonary hypertension (PH) is poorly understood. Transcription regulating, histone acetylation code alters chromatin accessibility to promote transcriptional activation. Our goal was to identify upstream mechanisms that disrupt epigenetic equilibrium in PH. Methods: Human pulmonary artery smooth muscle cells (PASMCs), human idiopathic pulmonary arterial hypertension (iPAH):human PASMCs, iPAH lung tissue, failed donor lung tissue, human pulmonary microvascular endothelial cells, iPAH:PASMC and non-iPAH:PASMC RNA-seq databases, NanoString nCounter, and cleavage under targets and release using nuclease were utilized to investigate histone acetylation, hyperacetylation targets, protein and gene expression, sphingolipid activation, cell proliferation, and gene target identification. SPHK2 (sphingosine kinase 2) knockout was compared with control C57BL/6NJ mice after 3 weeks of hypoxia and assessed for indices of PH. Results: We identified that Human PASMCs are vulnerable to the transcription-promoting epigenetic mediator histone acetylation resulting in alterations in transcription machinery and confirmed its pathological existence in PH:PASMC cells. We report that SPHK2 is elevated as much as 20-fold in iPAH lung tissue and is elevated in iPAH:PASMC cells. During PH pathogenesis, nuclear SPHK2 activates nuclear bioactive lipid S1P (sphingosine 1-phosphate) catalyzing enzyme and mediates transcription regulating histone H3K9 acetylation (acetyl histone H3 lysine 9 [Ac-H3K9]) through EMAP (endothelial monocyte activating polypeptide) II. In iPAH lungs, we identified a 4-fold elevation of the reversible epigenetic transcription modulator Ac-H3K9:H3 ratio. Loss of SPHK2 inhibited hypoxic-induced PH and Ac-H3K9 in mice. We discovered that pulmonary vascular endothelial cells are a priming factor of the EMAP II/SPHK2/S1P axis that alters the acetylome with a specificity for PASMC, through hyperacetylation of histone H3K9. Using cleavage under targets and release using nuclease, we further show that EMAP II-mediated SPHK2 has the potential to modify the local transcription machinery of pluripotency factor KLF4 (Krüppel-like factor 4) by hyperacetylating KLF4 Cis-regulatory elements while deletion and targeted inhibition of SPHK2 rescues transcription altering Ac-H3K9. Conclusions: SPHK2 expression and its activation of the reversible histone H3K9 acetylation in human pulmonary artery smooth muscle cell represent new therapeutic targets that could mitigate PH vascular remodeling.
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    Elongator protein 3 (Elp3) lysine acetyltransferase is a tail-anchored mitochondrial protein in Toxoplasma gondii
    (Elsevier, 2013) Stilger, Krista L.; Sullivan, William J., Jr.; Pharmacology and Toxicology, School of Medicine
    Background: Protein acetylation is prevalent in mitochondria, yet acetyltransferases mediating this activity are unknown. Results: Toxoplasma Elongator protein 3 (Elp3) possesses a unique C-terminal transmembrane domain necessary and sufficient to target it to the mitochondria. Conclusion: Elp3 is an essential tail-anchored mitochondrial acetyltransferase in Toxoplasma. Significance: Elp3 has conserved functions involving mitochondria that may predate its established role in transcription.
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    Glucocorticoid hormone-induced chromatin remodeling enhances human hematopoietic stem cell homing and engraftment
    (Nature Publishing Group, 2017-04) Guo, Bin; Huang, Xinxin; Cooper, Scott; Broxmeyer, Hal E.; Microbiology and Immunology, School of Medicine
    Efficient hematopoietic stem cell (HSC) homing is important for hematopoietic cell transplantation (HCT), especially when HSC numbers are limited, as in the use of cord blood (CB). In a screen of small-molecule compounds, we identified glucocorticoid (GC) hormone signaling as an activator of CXCR4 expression in human CB HSCs and hematopoietic progenitor cells (HPCs). Short-term GC pretreatment of human CB HSCs and HPCs promoted SDF-1-CXCR4-axis-mediated chemotaxis, homing, and long-term engraftment when these cells were transplanted into primary- and secondary-recipient NSG mice. Mechanistically, activated glucocorticoid receptor binds directly to a glucocorticoid response element in the CXCR4 promoter and recruits the SRC-1-p300 complex to promote H4K5 and H4K16 histone acetylation, facilitating transcription of CXCR4. These results suggest a new and readily available means to enhance the clinical efficacy of CB HCT.
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    HPV replication regulation by acetylation of a conserved lysine in the E2 protein
    (2017-06-26) Thomas, Yanique Serge Gillana; Androphy, Elliot J.; Klemsz, Michael; Yu, Andy; Mayo, Lindsey; Lee, Suk-Hee
    Papillomaviruses (PVs) are non-enveloped DNA viruses that are the primary etiological agents of cervical and oropharyngeal cancers. Vaccines for H(human)PV have proven to be effective prophylactic treatments; however, there is no treatment available for those currently infected. To develop new therapies, we require a clear understanding of viral pathogenesis and regulation. The Papillomavirus E2 protein is a sequence specific DNA binding protein that recruits cellular factors to its genome in infected epithelial cells. E2 also binds to and loads the viral E1 DNA helicase at the origin of replication. Post-translational modifications of PV E2 have been identified as potential regulators of E2 functions. We recently reported lysine (K) 111 as a target of p300 acetylation in B(bovine)PV that is involved in the regulation of viral transcription. K111 is conserved in most papillomaviruses, so we pursued a mutational approach to query the functional significance of lysine in HPV E2. Amino acid substitutions that prevent acetylation, including arginine, were unable to stimulate transcription and E1 mediated DNA replication. The arginine K111 mutant retained E2 transcriptional repression, nuclear localization, DNA and chromatin binding, and association with E2 binding partners involved in PV transcription and replication. When directly investigating origin unwinding, the replication defective E2 K111R mutant recruited E1 to the viral replication origin, but surprisingly, unwinding of the duplex DNA did not occur. In contrast, the glutamine K111 mutant increased origin melting and stimulated replication compared to wild type E2. We have identified Topoisomerase I as a key host factor involved in viral replication whose recruitment is dependent on K111 acetylation, and propose a new model for viral origin dynamics during replication initiation. This work reveals a novel activity of E2 necessary for denaturing the viral origin that likely depends on acetylation of highly conserved lysine 111.
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    Human Papillomavirus Replication Regulation by Acetylation of a Conserved Lysine in the E2 Protein
    (American Society for Microbiology, 2018-01-17) Thomas, Yanique; Androphy, Elliot J.; Microbiology and Immunology, School of Medicine
    The papillomavirus (PV) E2 protein is a sequence-specific DNA binding protein that recruits cellular factors to its genome in infected epithelial cells. E2 also binds to and loads the viral E1 DNA helicase at the origin of replication. Posttranslational modifications (PTMs) of PV E2 have been identified as potential regulators of E2 functions. We recently reported lysine 111 (K111) as a target of p300 acetylation in bovine PV (BPV). The di-lysines at 111 and 112 are conserved in almost all papillomaviruses. We pursued a mutational approach to query the functional significance of lysine in human PV (HPV) E2. Amino acid substitutions that prevent acetylation, including arginine, were unable to stimulate transcription and E1-mediated DNA replication. The arginine K111 mutant retained E2 transcriptional repression, nuclear localization, DNA and chromatin binding, and association with E2 binding partners involved in PV transcription and replication. While the replication-defective E2-K111R mutant recruited E1 to the viral replication origin, surprisingly, unwinding of the duplex DNA did not occur. In contrast, the K111 glutamine (K111Q) mutant increased origin melting and stimulated replication compared to wild-type E2. These experiments reveal a novel activity of E2 necessary for denaturing the viral origin that likely depends on acetylation of highly conserved lysine 111.IMPORTANCE HPV is one of the most common sexually transmitted infections in the United States. Over 200 HPVs have been described, and they manifest in a variety of ways; they can be asymptomatic or can result in benign lesions (papillomas) or progress to malignancy. Although 90% of infections are asymptomatic and resolve easily, HPV16 and -18 alone are responsible for 70% of all cervical cancers, which are almost entirely caused by HPV infection. Interestingly, 60 to 90% of other cancers have been linked to HPV. The goal of this research is to further elucidate the mechanisms that regulate and mediate viral replication.
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    Identification and characterization of altered mitochondrial protein acetylation in Friedreich's ataxia cardiomyopathy
    (Hindawi Publishing Corporation and Oxford Journals and SAGE Journals, 2011) Wagner, Gregory Randall; Payne, R. Mark; Dong, X. Charlie; Herbert, Brittney-Shea; Shou, Weinian
    Friedreich’s Ataxia (FRDA) is a rare and poorly understood autosomal recessive disease caused by a pathological deficiency of the mitochondrial protein frataxin. Patients suffer neurodegeneration, ataxia, diabetes, and heart failure. In an effort to understand the mechanisms of heart failure in FRDA, we investigated the role of the protein modification acetylation, which is highly abundant on mitochondrial proteins and has been implicated in regulating intermediary metabolism. Using mouse models of FRDA, we found that cardiac frataxin deficiency causes progressive hyperacetylation of mitochondrial proteins which is correlated with loss of respiratory chain subunits and an altered mitochondrial redox state. Mitochondrial protein hyperacetylation could be reversed by the mitochondria-localized deacetylase SIRT3 in vitro, suggesting a defect in endogenous SIRT3 activity. Consistently, frataxin-deficient cardiac mitochondria showed significantly decreased rates of fatty acid oxidation and complete oxidation to carbon dioxide. However, the degree of protein hyperacetylation in FRDA could not be fully explained by SIRT3 loss. Our data suggested that intermediary metabolites and perhaps acetyl-CoA, which is required for protein acetylation, are accumulating in frataxin-deficient mitochondria. Upon testing the hypothesis that mitochondrial protein acetylation is non-enzymatic, we found that the minimal chemical conditions of the mitochondrial matrix are sufficient to cause widespread non-enzymatic protein acetylation in vitro. These data suggest that mitochondrial protein hyperacetylation in FRDA cardiomyopathy mediates progressive post-translational suppression of mitochondrial oxidative pathways which is caused by a combination of SIRT3 deficiency and, likely, an accumulation of unoxidized acetyl-CoA capable of initiating non-enzymatic protein acetylation. These findings provide novel insight into the mechanisms underlying a poorly understood and fatal cardiomyopathy and highlight a fundamental biochemical mechanism that had been previously overlooked in biological systems.
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    Identification of TgElp3 as an essential, tail-anchored mitochondrial lysine acetyltransferase in the protozoan pathogen toxoplasma gondii
    (2014-07-11) Stilger, Krista L.; Nass, Richard M.; Bauer, Margaret E.; Oxford, G. S.; Queener, Sherry F.; Sullivan, William J., Jr.
    Toxoplasma gondii, a single-celled eukaryotic pathogen, has infected one-third of the world’s population and is the causative agent of toxoplasmosis. The disease primarily affects immunocompromised individuals such as AIDS, cancer, and transplant patients. The parasites can infect any nucleated cell in warm-blooded vertebrates, but because they preferentially target CNS, heart, and ocular tissue, manifestations of infection often include encephalitis, myocarditis, and a host of neurological and ocular disorders. Toxoplasma can also be transmitted congenitally by a mother who becomes infected for the first time during pregnancy, which may result in spontaneous abortion or birth defects in the child. Unfortunately, the therapy currently available for treating toxoplasmosis exhibits serious side effects and can cause severe allergic reactions. Therefore, there is a desperate need to identify novel drug targets for developing more effective, less toxic treatments. The regulation of proteins via lysine acetylation, a reversible post-translational modification, has previously been validated as a promising avenue for drug development. Lysine acetyltransferases (KATs) are responsible for the acetylation of hundreds of proteins throughout prokaryotic and eukaryotic cells. In Toxoplasma, we identified a KAT that exhibits homology to Elongator protein 3 (TgElp3), the catalytic component of a transcriptional elongation complex. TgElp3 contains the highly conserved radical S-adenosylmethionine and KAT domains but also possesses a unique C-terminal transmembrane domain (TMD). Interestingly, we found that the TMD anchors TgElp3 in the outer mitochondrial membrane (OMM) such that the catalytic domains are oriented towards the cytosol. Our results uncovered the first tail-anchored mitochondrial KAT reported for any species to date. We also discovered a shortened form of Elp3 present in mouse mitochondria, suggesting that Elp3 functions beyond transcriptional elongation across eukaryotes. Furthermore, we established that TgElp3 is essential for parasite viability and that its OMM localization is important for its function, highlighting its value as a potential target for future drug development.
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    Insights into the genetic architecture of the human face
    (Springer Nature, 2021) White, Julie D.; Indencleef, Karlijne; Naqvi, Sahin; Eller, Ryan J.; Hoskens, Hanne; Roosenboom, Jasmien; Lee, Myoung Keun; Li, Jiarui; Mohammed, Jaaved; Richmond, Stephen; Quillen, Ellen E.; Norton, Heather L.; Feingold, Eleanor; Swigut, Tomek; Marazita, Mary L.; Peeters, Hilde; Hens, Greet; Shaffer, John R.; Wysocka, Joanna; Walsh, Susan; Weinberg, Seth M.; Shriver, Mark D.; Claes, Peter; Biology, School of Science
    The human face is complex and multipartite, and characterization of its genetic architecture remains challenging. Using a multivariate genome-wide association study meta-analysis of 8,246 European individuals, we identified 203 genome-wide-significant signals (120 also study-wide significant) associated with normal-range facial variation. Follow-up analyses indicate that the regions surrounding these signals are enriched for enhancer activity in cranial neural crest cells and craniofacial tissues, several regions harbor multiple signals with associations to different facial phenotypes, and there is evidence for potential coordinated actions of variants. In summary, our analyses provide insights into the understanding of how complex morphological traits are shaped by both individual and coordinated genetic actions.