USA Department of Biochemistry & Molecular Biology Faculty
Ronald D. Balczon, Ph.D.
Postdoctoral Studies, Baylor College of Medicine and University of Alabama at Birmingham
Ph.D., Florida State University
My research is focused on the role of the microtubule cytoskeleton in health and disease. Our past research has investigated how microtubules maintain the pulmonary endothelial cell barrier and how disruption of microtubules leads to pulmonary edema. These studies have identified a critical role for the microtubule-associated protein tau in maintaining endothelial barrier function and have demonstrated that inhibition of tau activity leads to barrier breakdown and edema. Our more recent studies have focused on barrier disruption following infection with Pseudomonas aeruginosa. Pseudomonas aeruginosa infection is a principal cause of acute pneumonia that can progress to sepsis, acute lung injury, and death. During infection, Pseudomonas uses a type III secretion system to transfer bacterial exoenzymes into the cytoplasm of target cells. Our studies have shown that one of these exoenzymes, ExoY, targets tau resulting in defective microtubule dynamics, pulmonary endothelial breakdown, and edema. Studies in progress are investigating long-term effects of Pseudomonas infection on patient health and survival.
- Wu, S., Chen, H., Alexeyev, M.F., King, J.A.C., Moore, T.M., Stevens, T, and Balczon, R.D. 2007. Microtubule motors regulate ISOC activation necessary to increase endothelial cell permeability. J. Biol. Chem. 282:34801-34808.
- Prasain, N., Alexeyev, M., Balczon, R., and Stevens, T. 2009. Soluble adenylyl cyclase-dependent microtubule disassembly reveals a novel mechanism of endothelial cell retraction. Am. J. Physiol. Lung Cell Molec. Physiol. 297:L73-83. PMCID: PMC2711814.
- Ochoa, C.D., Stevens, T., and Balczon, R. 2011. Cold exposure reveals two populations of microtubules in pulmonary endothelia. Am. J. Physiol. Lung Cell Molec. Physiol. 300:L132-138.
- Sayner, S.L., Balczon, R., Frank, D.W., Cooper, D.M., and Stevens, T. 2011. Filamin A is a phosphorylation target of membrane but not cytosolic adenylyl cyclase activity. Am. J. Physiol. Lung Cell Molec. Physiol. 300:L132-138.
- Zeng, H., Pappas, C., Belser, J.A., Houser, K.V., Zhong, W., Wadford, D.A., Stevens, T., Balczon, R., Katz, J.M., and Tumpey, T.M. 2012. Human pulmonary microvascular endothelial cells support productive replication of highly pathogenic avian influenza viruses: possible involvement in the pathogenesis of human H5N1 virus infection. J. Virology 86:667-678.
- Ochoa, C.D., Alexeyev, M., Pastukh, V., Balczon, R., and Stevens, T. 2012. Pseudomonas aeruginosa exotoxin Y is a promiscuous cyclase that increases endothelial cell tau phosphorylation and permeability. J. Biol. Chem. 287:25407-25418.
- Balczon, R., Prasain, N., Ochoa, C., Prater, J., Zhu, B., Alexeyev, M., Sayner, S., Frank, D.W., and Stevens, T. 2013. Pseudomonas aeruginosa exotoxin Y-mediated tau hyperphosphorylation impairs microtubule assembly in pulmonary microvascular endothelial cells. PLoS One 8:e74343.
- Stevens, Tr., Ochoa, C., Morrow, K., Robson, M., Prasain, N., Zhou, C., Alvarez, D., Frank, D., Balczon, R., and Stevens, T. 2014. The Pseudomonas aeruginosa exotoxin Y impairs endothelial cell proliferation and vascular repair following lung injury. Am. J. Physiol. Lung Cell Molec. Physiol. 306:L915-L924.
Christopher Davies, Ph.D.
Professor and Associate Dean for Research
Ph.D., University of Bristol
The primary interest of my laboratory is structure and function investigations of enzymes involved in peptidoglycan metabolism in bacteria. Much of our work to date has focused on penicillin-binding proteins (PBPs), starting with investigations of catalytic mechanism and then progressing to understanding mechanisms of antibiotic resistance. Our investigations have included PBPs from E. coli, M. tuberculosis, P. aeruginosa and N. gonorrhoeae. A major focus at present is to understand the impact of mutations in penicillin-binding protein 2 (PBP2) derived from cephalosporin-resistant strains of N. gonorrhoeae (including H041, identified in Japan, and F89, identified in France). Such strains signal a possible end to treatable gonorrhea and it is therefore important to elucidate the molecular mechanisms underlying antibiotic resistance. In particular, we seek to understand how mutations in PBP2 lower inhibition by cephalosporins without affecting the essential transpeptidase reaction with peptide substrate. The long-term goal is to employ this information for the design of new anti-gonococcal agents that overcome resistance mechanisms.
Toward that goal, we are increasingly engaged in drug discovery and development efforts targeting N. gonorrhoeae PBP2. Current efforts are directed toward testing and optimization of non-β-lactam PBP2 inhibitors identified through high-throughput screening against chemical and in silico libraries, and we are also working with a pharmaceutical company who are developing lead inhibitors of PBP2.
- Fenton, B.A., Tomberg, J., Sciandra, C.A., Nicholas, R.A., Davies, C. & Zhou, P. (2021). Mutations in PBP2 from ceftriaxone-resistant Neisseria gonorrhoeae alter the dynamics of the β3-β4 loop to favor a low-affinity drug-binding state. J Biol Chem. 297: Oct; 297(4):101188. doi: 10.1016/j.jbc.2021.101188. PMCID: PMC8503634.
- Singh, A., Izac, J.R., Schuler, E.J.A., Patel, D.T., Davies, C. & Marconi RT. (2021). High-resolution crystal structure of the Borreliella burgdorferi PlzA protein in complex with c-di-GMP: new insights into the interaction of c-di-GMP with the novel xPilZ domain. Pathog Dis. Jun 29;79(5). doi: 10.1093/femspd/ftab030. PMCID: PMC8240479.
- Turner, J.M., Connolly, K.L., Aberman, K.E., Fonseca, J.C. 2nd, Singh, A., Jerse, A.E., Nicholas, R.A. & Davies, C. (2021) Molecular Features of Cephalosporins Important for Activity against Antimicrobial-Resistant Neisseria gonorrhoeae. ACS Infect Dis. Feb 12;7: 293-308. doi: 10.1021/acsinfecdis.0c00400.
- Singh, A., Turner, J.M., Tomberg, J., Fedarovich, A., Unemo, M., Nicholas, R.A. & Davies, C. (2020). Mutations in penicillin-binding protein 2 from cephalosporin-resistant Neisseria gonorrhoeae hinder ceftriaxone acylation by restricting protein dynamics. J Biol Chem. 295:7529-7543. doi: 10.1074/jbc.RA120.012617. PMCID: PMC7247294.
- Singh, A., Tomberg, J., Nicholas, R.A. & Davies, C. (2019). Recognition of the β-lactam carboxylate triggers acylation of Neisseria gonorrhoeae penicillin-binding protein 2. J Biol Chem. 294: 14020-14032. doi: 10.1074/jbc.RA119.009942. PMCID: PMC6755799.
- Johnsen, U., Reinhardt, A., Landan, G., Tria, F.D.K., Turner, J.M., Davies, C. & Schönheit, P. (2019). New views on an old enzyme: allosteric regulation and evolution of archaeal pyruvate kinases. FEBS J. 286: 2471-2489. doi: 10.1111/febs.14837.
- Young, B.F., Roth, B.M. & Davies, C. (2019). 1H, 13C, and 15N resonance assignments of N-acetylmuramyl-L-alanine amidase (AmiC) N-terminal domain (NTD) from Neisseria gonorrhoeae. Biomol NMR Assign. 13: 63-66. doi: 10.1007/s12104-018-9852-1. PMCID: PMC6440844.
Simon Grelet, Ph.D.
Postdoctoral Studies, Medical University of South Carolina, Hollings Cancer Center
Ph.D., Reims University, France
Embryo-related tumor cell plasticity & primary tumor neurogenesis.
Metastasis is the overwhelming cause of mortality in patients with solid tumors. To survive and disseminate, the tumor cells need to constantly adapt to their surrounding environment. Tumor cell plasticity associated with the epithelial-mesenchymal transition (EMT), a program observed in embryonic development, is reactivated during carcinomas progression and correlates with tumor dissemination and resistance to therapies. While observed in vivo, the EMT program is a highly dynamic and often incomplete process, resulting in cells exhibiting diverse intermediate states that maintain both epithelial and mesenchymal characteristics.
My laboratory explores the molecular mechanisms that are balancing tumor cell phenotypes and their biological impacts on the tumor microenvironment. By using genome-wide sequencing methodologies and CRISPR gene editing libraries applied to lineage tracing models, we identify new factors involved in the tumor-stroma interaction. Our current research focuses on primary tumor neurogenesis with a special emphasis on the contribution of post-transcriptional regulation and non-coding RNA species in this biological process.
Tumor neurogenesis is closely related to metastatic progression and is associated with poor clinical outcomes. The little-understood molecular mechanisms of cancer–nerve crosstalk represent therapeutic opportunities and our approach is intended to provide new tools in the prevention of cancer dissemination.
Research training positions are available for postdoc and graduate students. Email firstname.lastname@example.org.
Research training will provide you the skills that are required for studying the Molecular Biology of the Cell as well as critical knowledge in the areas of both Cancer/Neuron cell Biology and Bioinformatics applied to high-throughput methodologies.
Richard E. Honkanen, Ph.D.
Professor and Chair
Ph.D., University of Georgia, 1986
Protein Phosphatases ( Molecular mechanisms of carcinogenesis; Mechanisms of cardioprotective agents in ischemic myocytes).
The reversible phosphorylation of many proteins determines their biological activity and is a key mechanism controlling intracellular events as diverse as metabolism, contractility, cell division, hormonal action and signal transduction. This phosphorylation/dephosphorylation of proteins occurs on specific serine, threonine, or tyrosine residues and represents a dynamic equilibrium between the activities of both protein kinases and protein phosphatases.
In my laboratory, we are currently studying the molecular mechanisms associated with cancer, coronary heart disease and diabetes. The common theme of our research is the functions of specific protein phosphatases. A major goal of our cancer research is to identify and clone novel protein phosphatases that may play a role in the aberrant proliferative behavior of neoplastic cells. We have also identified a number of natural marine toxins with specific and potent inhibitory activity against certain protein phosphatases. Some of these "toxins" alter the cell cycle progression of tumor cells in culture, and we are interested in determining if these compounds have the potential for development into novel drugs for the treatment of certain cancers. We are also developing techniques to better use these phosphatase inhibitors for the identification of novel protein phosphatases and to study the roles of specific phosphatases in normal and aberrant cellular functions. We are also interested in the identification and development of novel type specific inhibitors.
2011 NIH Director's Transformative RO1 Award: Methods To Enable Cholesterol Catabolism In Human Monocyte Derived Macrophages
Aishwarya Prakash, Ph.D.
Postdoctoral Studies, University of Vermont
Ph.D., University of Nebraska Medical Center
Various factors in our environment including ionizing radiation, chemicals found in cigarette smoke, herbicides, and known carcinogenic metals as well as normal cellular processes, generate reactive oxygen species (ROS) in a cell. ROS cause assault to DNA that leads to nuclear and mitochondrial DNA (mtDNA) damage where unrepaired damage to DNA results in mutagenesis and diseases including premature aging, neurodegenerative disorders, and various cancers. I began my independent research career as a tenure-track Assistant Professor at the University of South Alabama Mitchell Cancer Institute, Department of Biochemistry and Molecular Biology, in March 2016.
A part of my laboratory has been engaged with performing fundamental studies on the biochemistry and structural biology of base excision repair (BER) complexes involved in the repair of non-bulky lesions formed in mtDNA. We have identified components of the mitochondrial replication and transcriptional machinery that interact directly with the NEIL DNA glycosylases, which are oxidized-lesion specific enzymes that catalyze the first step of BER. Furthermore, we are interested in three aspects of NEIL-enzyme regulation including (1) identifying the subcellular localization of NEIL enzymes in response to oxidative stress, (2) regulation of NEIL activity by post- translational modifications, and (3) structure-driven functional studies that seek to identify unique protein interacting partners of the NEIL enzymes, which are essential for successful repair (Fig. 1). These aspects are intimately involved with understanding the role of environmental factors in driving mutagenesis.
More recently, my laboratory has been involved with performing experiments to aid in the reclassification of variants of uncertain significance (VUS) in mismatch repair genes whose loss of function leads to a hereditary cancer syndrome known as Lynch syndrome (LS). VUSs are challenging for patient medical management as functional information regarding the variant is unavailable. The focus of my lab is to use functional assays to recharacterize VUSs as either pathogenic (leads to a higher risk for disease) or benign (not disease causing) (Fig. 2). We are currently extending these studies to analyze the contribution of environmental toxicants such as cadmium (a known carcinogen) in driving cancer progression in LS patients.
Wito Richter, Ph.D.
Ph.D., Leipzig University, Leipzig, Germany, 2000
Cyclic nucleotide signaling and cAMP phosphodiesterases
Cyclic adenosine monophosphate (cAMP) is a ubiquitous second messenger that regulates a myriad of physiological processes. Its cellular concentration is determined by the rate of its synthesis by adenylyl cyclases and the rate of its degradation by cyclic nucleotide phosphodiesterases (PDEs). The mammalian PDEs encompass a large number of isoenzymes grouped into eleven families. Our laboratory explores the structure, regulation and physiological functions of Type 4 PDEs (PDE4s), the largest and most widely expressed PDE family.
The PDE4 family comprises four genes, PDE4A-D, that together are expressed as more than 25 protein variants. PDE4 inactivation produces a number of therapeutic benefits, including anti-inflammatory and memory- and cognition-enhancing effects, and has been pursued as a therapeutic approach for a number of indications. However, the non-selective PDE4 inhibitors available to date also produce significant side effects that limit their clinical utility. Individual PDE4 variants exert unique and non-overlapping physiological and pathophysiological roles by controlling cAMP levels in microdomains of signaling, to which they are tethered via variant-specific protein/protein or protein/lipid interactions, rather than on the global cellular scale. Our group aims to dissect the roles of individual PDE4 variants in diverse cells and tissues to verify individual PDE4s and PDE4 signaling complexes as drug targets. In addition, we explore regulatory and structural differences between individual PDE4s for the development of isoform-selective PDE4 inhibitors with an improved safety profile compared to the non-selective PDE4 inhibitors available to date.
Research training positions are available for postdoc and graduate students. Email email@example.com.
Mark Swingle, Ph.D.
Postdoctoral Studies, University of South Alabama
Ph.D., University of South Alabama
Protein phosphatase function and regulation. Assay/screening development and ligand discovery.
Reversible phosphorylation of structural and regulatory proteins plays a crucial role in the regulation of many cellular functions in eukaryotes, affecting a large and diverse panoply of cellular processes. Phosphorylation occurs principally upon serine, threonine, and tyrosine residues and is mediated by members of an extremely large group of ser/thr- and tyr-protein kinases, which catalyze the transfer of a gamma phosphate from ATP to the side chain hydroxyl. Dephosphorylation is accomplished by one or more of the >150 ser/thr-, tyr-, or dual-specificity phosphatases, which catalyze the hydrolysis of seryl, threonyl, and/or tyrosyl phosphomonoesters, respectively. The biological activity of a protein, its location within a cell, its stability, and interactions with other macromolecules can all be affected by its phosphorylation state, which is governed dynamically via coordinated regulation of the kinases and phosphatases that utilize it as a substrate.
My laboratory is currently focused upon two members of the PPP family of protein phosphatases: PP5, a key part of the HSP90 chaperone machinery, and PP2A, one of the most abundant cellular phosphatases, which is subject to very complex regulation via assembly into a bewildering variety of functional heterotrimeric holoenzymes. Through our studies we hope to develop a better understanding of the cellular functions of these phosphatases, the mechanisms by which they are regulated, and their potential roles in various disease processes. In addition, my laboratory has an abiding interest in pursuing ligand discovery efforts aimed at developing novel type-specific inhibitors and activators of PPP phosphatases as research tools and/or potential leads for drug development
Dr. Singh, Ajay, Ph.D.
Postdoctoral Studies, UNMC/Eppley Cancer Institute
Ph.D., Devi Ahilya University
The molecular mechanisms of cancer progression, metastasis and chemoresistance, and utilizing the mechanistic insight to develop novel approaches for cancer therapy and prevention. Dr. Singh has published extensively (over 100 research articles, reviews and book chapters) and holds five US patents. He also serves on the editorial boards of several scientific journals. Research programs in his laboratory have been supported through all major federal funding agencies, including NIH and DOD, and by the state of Nebraska’s and Alabama’s health departments. Dr. Singh actively serves on grant review panel boards of national and international funding agencies and private foundations that provide support for cancer research.
Santanu Dasgupta, Ph.D.
Postdoctoral Studies, Johns Hopkins School of Medicine
Ph.D., Chittaranjan National Cancer Institute
Mitochondria play a significant role in human tumorigenesis. Dasgupta laboratory is keenly interested to learn how cancer cells evolve by reprogramming mitochondrial functions and apply this knowledge for the strategic development of biomarkers and therapeutics. Dasgupta laboratory is also interested in exosome related studies to unravel their potential use in biomarker and therapeutic development. Dr. Dasgupta has published over 70 peer reviewed articles and currently serves as an editorial board member in several cancer related journals. He also served as a grant reviewer of national and international agencies including NIH, Cancer Research UK fund and mentored several graduate students and postdoctoral fellows
Seema Singh, Ph.D.
Postdoctoral Studies, UNMC/Eppley Cancer Institute
Ph.D., Devi Ahilya University
Inflammation, immunobiology, nanotechnology, and cancer health disparities. She and her team are actively investigating the role of inflammatory cytokines and stress hormones in cancer progression and metastasis. They are also developing novel nanoformulations to improve drug delivery. Research programs in her laboratory have been supported from the National Cancer Institute (NCI/NIH). Dr. Singh has published extensively (over 90 research articles, reviews and book chapters) and holds US patents. She has co-founded a Biotech start-up company, Tatva Biosciences., and actively serves on the editorial boards of several scientific journals and grant review panels of national and international funding agencies.
Singh, Ajay, Ph.D., Professor
Mitchell Cancer Institute
Email: firstname.lastname@example.org • (251) 445-9873
Singh, Seema, Ph.D., Professor
Mitchell Cancer Institute
Email: email@example.com • (251) 445-9873
Dasgupta, Santanu, Ph.D., Assistant Professor
Mitchell Cancer Institute
Email: firstname.lastname@example.org • (251) 471-7719