Navigate Up
Sign In
Johns Hopkins Medicine web site Johns Hopkins Medical Institutes Biological Chemistry Home
Natasha Zachara Portrait

Natasha Zachara
Assistant Professor of Biological Chemistry
Johns Hopkins University School of Medicine

Department of Biological Chemistry
725. N. Wolfe Street, WBSB 408
Baltimore, MD21205
Office Phone: 410-955-7049
Lab Phone: 410-502-3210
Fax: 410-955-5759
Email: nzachara@jhmi.edu
Lab Web Site

Click Here for PDF of CV

The role of nucleocytoplasmic glycosylation, O-GlcNAc, in cell survival and the celluar stress response.

Hundreds, if not thousands, of key cellular proteins in the nucleus, mitochondria and cytoplasm of metazoans are modified by O-linked β-N-acetylglucosamine (O-GlcNAc). Deletion of the UDP-GlcNAc: polypeptide O-β-N-acetyl-glucosaminyltransferase (OGT), the enzyme that adds O-GlcNAc, is lethal in animals and single cells highlighting the importance of this simple post-translational modification. O-GlcNAc is thought to act as a modulator of protein function, in a manner analogous to protein phosphorylation; the addition of O-GlcNAc to the protein backbone is dynamic, responding to morphogens, the cell cycle, changes in glucose metabolism, and cellular injury. O-GlcNAc occurs at sites on the protein backbone that are similar to those modified by protein kinases; and is reciprocal with phosphorylation on some well studied proteins, including RNA Pol II, estrogen receptor-β, SV-40 large T-antigen, endothelial nitric oxide synthase, and the c-Myc proto-oncogene product. These data suggest that one mechanism by which O-GlcNAc modulates cellular function is by competing with phosphorylation. A clear role for O-GlcNAc in cellular regulation has not emerged, although modulation of O-GlcNAc levels are implicated in the etiology of Type II Diabetes, cancer, and neurodegenerative diseases.

In response to multiple forms of cellular stress, levels of the O-GlcNAc protein modification are elevated rapidly and dynamically on myriad nuclear, mitocohdrial and cytoplasmic proteins. Several studies demonstrate that elevation of O-GlcNAc prior to heat stress, oxidative stress, hypoxia, trauma hemorrhage, and ischemia reperfusion injury is protective, suggesting that increased O-GlcNAc in response to stress is a survival response of cells injury. However, the mechanisms by which O-GlcNAc regulates protein function leading to cell survival have not been defined. Our long-term goal is to determine how stress-induced changes in the O-GlcNAc protein modification lead to increased cell/tissue survival in response to injury, in order to develop novel strategies for the treatment of numerous diseases, including ischemia reperfusion injury. Current research in the lab focus's on: 1) Characterizing the molecular mechanisms by which O-GlcNAc regulates heat shock protein expression; 2) The development of novel cells lines and tools for studying the O-GlcNAc modification; 3) Identifying proteins that are O-GlcNAc modified in response to different forms of cellular injury; 4) Understanding the signal transduction pathways that regulate O-GlcNAc modification in response to cellular injury; 5) Determining how O-GlcNAc regulates other stress-induced signaling pathways such as protein-phosphorylation. Together these studies will define a molecular road map from which we, and others, can determine the mechanism(s) by which O-GlcNAc promotes cell survival in diverse models, highlighting new targets for the development of alternative strategies that enhance stress-tolerance and promotes survival relevant models such as ischemic reperfusion injury. In addition, these studies will form a foundation for determining how dysregulation of the “O-GlcNAc-mediated stress response” contributes to pathologies such as type II diabetes and aging.

Recent Publications

N.E. Zachara The Roles of O-Linked β-N-Acetylglucosamine (O-GlcNAc) in Cardiac Physiology and Disease. AJP, In Press.

N.E. Zachara, H. Molina, K. Wong, A. Pandey, G.W. Hart (2011) The dynamic stress-induced O-GlcNAcome highlights functions for O-GlcNAc in DNA Repair and other cellular pathways. Amino Acids, 40(3):793-808.
PubMed Reference

V.D.P. Paruchuri and N. E. Zachara. “Defining the Cardiac O-GlcNAcome, A Review of Approaches and Methasologies”, Special series: Integrating proteomics into cardiovascular disease in Circulation: Cardiovascular Genetics, 2011 Dec 1;4(6):710.
PubMed Reference

N. E. Zachara, Keith L Vosseller, and G. W. Hart (2011) Detection and analysis of proteins modified by O-Linked N-acetylglucosamine. In Current Protocols in Protein Science, Johns Wiley and Sons Inc., New York, USA. Chapter 12, Unit 12.8.
PubMed Reference 

Z. Kazemi, H. Chang, S. K. Haserodt, C. McKen, N.E. Zachara (2010) O-GlcNAc Regulates Stress-Induced Heat Shock Protein Expression in a GSK-3β Dependent Manner. J. Biol. Chem. Dec 10;285(50):39096-107. Epub 2010 Oct 6.
PubMed Reference

N.E. Zachara (2009). Detection and Analysis of Nuclearcytoplasmic Glycoproteins. In The Nucleus: Principles and Protocols, Meth Mol Biol. Hancock R (ed) Humana Press (Totowa, USA). Volume 464, pp. 227-254.
PubMed Reference

N. E. Zachara (2009) Detecting the “O-GlcNAc-ome”; Detection, Purification, and Analysis of O-GlcNAc Modified Proteins. In Glycomics, Meth Mol Biol. Packer N, Karlsson GN (eds) Humana Press (Totowa, USA). Volume 534, pp.251-79.
PubMed Reference

G. A. Ngoh, H. T. Facundo, T. Hamid, W. Dillmann, N. E. Zachara, Steven P. Jones (2009). Unique Hexosaminidase Reduces Metabolic Survival Signal and Sensitizes Cardiac Myocytes to Hypoxia-Reoxygenation Injury. Circ. Res. 104(1):41-9.
PubMed Reference

S. P. Jones, N.E. Zachara , Y. Teshima, G. W. Hart, and E. Marban. (2008) Endogenously-recruitable cardioprotection by N-acetylglucosamine linkage to cellular proteins. Circulation, 117(9):1172-82.
PubMed Reference

N.E. Zachara . (2007) The sweet nature of cardioprotection. Amer J Phys (Heart and Circulatory Physiology; 293: H1324-H1326.
PubMed Reference

N.E. Zachara and G. W. Hart. (2006) Cell Signaling, the Essential Role of O-GlcNAc! Biochim. Biophys. Acta, 1761: 599-617.
PubMed Reference

C. Slawson, N.E. Zachara , K. Vosseller, W. Cheung, M. D. Lane, and G. W. Hart (2005) Perturbations in O-GlcNAc protein modification cause severe defects in mitotic progression and cytokinesis. J. Biol. Chem., 280, 32944-32956.
PubMed Reference​

N. O'Donnell, N.E. Zachara , G. W. Hart, and J. D. Marth. (2004) OGT-dependent X-chromosome-linked intracellular protein glycosylation is essential for mammalian viability and cellular metabolism. Mol. Cell. Biol., 24, 1680-1690.
PubMed Reference

N.E. Zachara , N. O'Donnell, J. J. Mercer, J. D. Marth, and G. W. Hart. (2004) Dynamic O-GlcNAc modification of nucleocytoplasmic proteins in response to stress. A survival response of mammalian cells. J. Biol. Chem., 279, 30133-30142.
PubMed Reference

N.E. Zachara and G. W. Hart. (2004) O-GlcNAc a sensor of cellular state: The role of nucleocytoplasmic glycosylation in modulating cellular function in response to nutrition and stress. Biochim. Biophys. Acta., 1673, 13-28.
PubMed Reference

N.E. Zachara , W. D. Cheung, and G. W. Hart. (2004) Nucleocytoplasmic glycosylation, O-GlcNAc: identification and site mapping. In Signal Transduction Protocols, Methods in Molecular Biology, R. Dickson and M. Mendenhall (eds), Humana Press, Totowa, USA. Volume 284, pp.175-194.
PubMed Reference

© Copyright 2008-2012 Johns Hopkins University. All Rights Reserved.
Site development: Modern Tymes, LLC