Tight junctions are intercellular contacts that form a barrier required for ion transport and organization of cell polarity. Our lab investigates assembly and regulation of TJ proteins and the molecular basis for ion selectivity in epithelia.
We study the interface between signal transduction and cell function. Approaches employed include - molecular genetics, protein and lipid biochemistry, confocal and electron microscopy, protein crystallography, and model organisms approaches (e.g. yeast, Arabidopsis, C. elegans, mouse gene knockout technology).
We study interactions of proteins and peptides with membranes. Specifically we study the interaction of the A-beta peptide with lipids in the membrane. It is well known that Alzheimer’s is an aggregation disorder with A-beta being the aggregating species. However, it is unknown what initiates this aggregation. Experimental evidence has shown that A-beta peptides will undergo a conformational change to an aggregate structure when interacting with surfaces of certain lipid membranes. It is of interest to our group to understand what causes this conformational change and what properties of lipids most promote this effect.
We also study structural and dynamical properties of biomembranes containing cholesterol. The goal of our research on structural and dynamical properties of membranes containing cholesterol is to gain knowledge about the nature of phospholipid-cholesterol interactions that play an important role in functioning of membranes, in cell communications and in formation of domains called lipid rafts. Detailed knowledge of the membrane properties helps us to understand the normal functioning of cells and it is instrumental in the search for a cure from a large variety of diseases. We use computer simulation techniques to perform our studies. Member of the Molecular & Cellular Biophysics Training Program
Our long term goal is to define the molecular mechanisms of two-component regulatory systems, which are utilized for signal transduction by bacteria, archaea, eukaryotic microorganisms, and plants. Our current focus is to understand the features that control the rates of self-catalyzed phosphorylation and dephosphorylation of response regulator proteins. The kinetics of these reactions vary dramatically (>40,000x) between different pathways and reflect the need to synchronize biological responses (e.g. behavior, development, physiology, virulence) to environmental stimuli. Member of the Molecular & Cellular Biophysics Training Program
We are interested in the mechanism by which eukaryotic cells are polarized and the role of vesicle transport plays in the determination and regulation of cell polarity and tumorigenesis.
Current research projects in the Campbell laboratory include structural, biophysical and biochemical studies of wild type and variant Ras and Rho family GTPase proteins, as well as the identification, characterization and structural elucidation of factors that act on these GTPases. Ras and Rho proteins are members of a large superfamily of related guanine nucleotide binding proteins. They are key regulators of signal transduction pathways that control cell growth. Rho GTPases regulate signaling pathways that also modulate cell morphology and actin cytoskeletal organization. Mutated Ras proteins are found in 30% of human cancers and promote uncontrolled cell growth, invasion, and metastasis. Another focus of the lab is in biochemical and biophysical characterization of the cell adhesion proteins, focal adhesion kinase, vinculin, paxillin and palladin. These proteins are involved in actin cytoskeletal rearrangements and cell motility, amongst other functions. Most of our studies are conducted in collaboration with laboratories that focus on molecular and cellular biological aspects of these problems. This allows us to direct cell-based signaling, motility and transformation analyses. Member of the Molecular & Cellular Biophysics Training Program.
Molecular evolution and mechanistic enzymology find powerful synergy in our study of aminoacyl-tRNA synthetases, which translate the genetic code. Class I Tryptophanyl-tRNA Synthetase stores free energy as conformational strain imposed by long-range, interactions on the minimal catalytic domain (MCD) when it binds ATP. We study how this allostery works using X-ray crystallography, bioinformatics, molecular dynamics, enzyme kinetics, and thermodynamics. As coding sequences for class I and II MCDs have significant complementarity, we also pursuing their sense/antisense ancestry. Member of the Molecular & Cellular Biophysics Training Program.
Cross-talk between insulin like growth factor -1 and cell adhesion receptors in the regulation of cardiovascular diseases and complications associated with diabetes
We study how Cytotoxic T Lymphocytes (CTL) are activated during infection and cancer. Our long-term goal is to increase immunity in the case of infection or cancer and to decrease immunity in the case of autoimmunity. The approaches that we use include x-ray crystallography and other biophysical techniques such as SPR and ITC, and immunological assays. We are currently working on three systems. 1) basic immunology to understand how cytotoxic T cells are signaled to kill infected or cancer cells. 2) immunotherapy of melanoma using modified T cell receptors. 3) Determining why specific T cells populate pancreatic islets of Langerhans in Type I diabetes. Students working on these projects could work on immunological or biophysical aspects (or both) depending on their interests. Member of the Molecular & Cellular Biophysics Training Program.
The main research project is to determine the role of intercellular junctions in normal development, cell aging and cataract formation in human and animal lenses.
The Dokholyan group focuses primarily on understanding protein dynamics, more specifically on how induced changes in protein folding and aggregation lead to diseases, such as cystic fibrosis, many types of cancers, and a number of neurodegenerative diseases. The Dokholyan group focuses on several such diseases, including Amyotrophic Lateral Sclerosis (ALS), also known as Lou Gehrig’s disease, and Huntington disease. The Dokholyan group is developing a hierarchy of molecular models, from simplified coarse-grained models to more detailed ones, to create a novel multi-scale simulation methodology. This methodology will enable simulations of large molecular complexes at the biologically-relevant time scales, thereby allowing to directly glance into processes associated with human diseases. Member of the Molecular & Cellular Biophysics Training Program.
The research in my lab is divided into two main areas - 1) Atomic force microscopy and fluorescence studies of protein-protein and protein-nucleic acid interactions, and 2) Mechanistic studies of transcription elongation. My research spans the biochemical, biophysical, and analytical regimes.
Our work is focused on understanding how major histocompatibility complex (MHC) molecules function in the immune response to pathogens. This simple question involves the most fundamental aspect of immunology - self/non-self discrimination.
We are interested in basic DNA-protein interactions as related to - DNA replication, DNA repair and telomere function. We utilize a combination of state of the art molecular and biochemical methods together with high resolution electron microscopes.
We focus on mechanistic/structural aspects of regulatory proteins (heterotrimeric and Ras family GTPases, RGS proteins, and PLC isozymes) involved in inositol lipid signaling, and on G protein-coupled receptors for extracellular nucleotides.
Spatio-temporal regulation of signal relay systems in cells using live cell fluorescence imaging and targeted gene disruption of signaling proteins to define their role in development, physiology and pathophysiology.
Signal transduction coupled by heterotrimeric G proteins. We use Arabidopsis, genetics, biochemistry, & in vivo imaging of protein-protein interactions. The type of signals we study include light, hormones, & sugars.
Our research focuses on the structure and function of medically important proteins from the crystallographic approach. The current topics include cycolphilin, calcineurin, heat shock protein 90 (hsp90), and cyclic nucleotide phosphodiesterase.
We use a combination of experimental and computational methods to redesign protein-protein interactions. The potential applications for this technology include enhancing protein therapeutic and creating new tools to study signaling pathways.
We study protein structure and dynamics as they relate to protein function and energetics. We are currently using NMR spectroscopy (e.g. spin relaxation), computation, and a variety of other biophysical techniques to gain a deeper understanding of proteins at atomic level resolution. Of specific interest is the general phenomenon of long-range communication within protein structures, such as observed in allostery and conformational change. A. Lee is a member of the Molecular & Cellular Biophysics Training Program.
The regulatory role of platelet membrane phosphatidylserine in blood coagulation; mechanism of protein-mediated membrane fusion in secretory processes and virus infection. Director of the Molecular & Cellular Biophysics Training Program.
We study the blood clotting protein fibrinogen, its biochemistry and its role in disease (Curr Opin Hematol. 14:236, 2007). We synthesize variant fibrinogens to correlate structure and function using crystallographic and biochemical analyses (Biochemistry 46:5114, 2007). We examine the mechnical properties of fibrin fibers using atomic force microscopy (Science 313:634. 2006). We explore the interactions of fibrinogen with biomaterials (Acta Biomaterialia 3:663, 2007). We use patient samples and mouse models to examine the links between fibrinogen and disease (J Thromb Haemost. 2:1484, 2004). Member of the Molecular & Cellular Biophysics Training Program.
Our laboratory studies the mechanisms of sensory information processing in the nervous system, with an emphasis on processing in the auditory pathways. We study the role of ion channels in integration at the single cell level, short and long-term synaptic plasticity, synaptic function, and ion channel dynamics in the auditory brainstem and auditory cortex. We are also studying how different kinds of hearing loss affect central auditory function. Experimentally, we use patch clamp (current, voltage and dynamic clamp) methods in brain slices, live optical imaging of activity, a variety of biochemical and molecular methods, mice with genetic hearing loss, noise-induced hearing loss, auditory brainstem evoked response, and acoustic startle response to evaluate hearing function in animal models. The laboratory extensively utilizes quantitative experimental techniques, complemented with detailed computational modeling at the single cell and network levels to further understand the normal information processing capacity of auditory neurons, and the consequences of changes in ion channel and synaptic function after hearing loss.
Our lab investigates molecular and cellular mechanisms that regulate mammalian spermatogenesis and fertilization. A major focus of our current research is sperm energy metabolism. Our gene knockout studies demonstrate that glycolysis is essential for sperm motility and male fertility, and genomic analyses indicate that male germ cells express unique enzymes for nearly every step in this central metabolic pathway. These sperm-specific glycolytic enzymes have distinctive properties, as demonstrated by biochemical and structural analyses. Understanding how sperm energy production is regulated has significant therapeutic potential, both for the development of new contraceptive strategies and the clinical management of infertility.
We are a theoretical physical chemistry group in the Department of Chemistry at the University of North Carolina at Chapel Hill. We use advanced computational methods to study biological processes at multiple scales, from single protein functional dynamics and chromatin folding and stability to cell-level processes, such as stochastic signal transduction and regulation of cell motility.
My graduate students and I use the formalism of equilibrium thermodynamics and the tools of molecular biology and biophysics to understand how nature designs proteins.
High-performance computing: algorithms, programming languages, compilers and architectures. Scientific computing with focus on computational biology and bioinformatics. High-level programming languages and problem solving environments.
We examine dynamic cellular processes using structural biology. Current projects focus on Infectious disease, particularly the spread of antibiotic resistance and host-pathogen interactions; Protein-DNA complexes involved in DNA manipulation; the Design of protein therapeutics; Nuclear receptors in transcriptional control; and Enzymes central to drug recognition and metabolism.
The primary research focus is the structure, function and biosynthetic processing of membrane proteins which provide permeability pathways through the membranes of cells. Much of the current work is concentrated on the ion channel protein, CFTR (cystic fibrosis transmembrane conductance regulator) which is absent or dysfunctional in patients with cystic fibrosis. To elucidate the molecular mechanisms of CFTR function, we study single channel properties by electrophysiological techniques, enzymatic activity and physical interaction with other cellular molecules. A major objective of studies with the purified molecule is to obtain 3-dimensional structure information so that small molecules capable of recognizing features of its surface shape can be synthesized and used to modulate its folding and activity.
Cell adhesion controls cellular functions implicated in human disease, e.g. cancer. FAK, a tyrosine kinase, is a major component of this signaling pathway. We study the function and molecular mechanisms by which FAK controls these events.
Regulator of G-protein signaling (RGS) proteins accelerate the GTPase activity of G-alpha subunits and thereby act as critical negative regulators of hormone and neurotransmitter signaling via G protein-coupled receptors. Our lab first recognized the existence of these critical signaling regulators in 1996. We continue to study their structural and functional diversity, as well as their roles in physiological and disease processes, including immunity, oncogenic transformation, and pain processing.
Our lab examines cytoskeletal dynamics, the molecules that regulate it and the biological processes it is involved in using live cell imaging, in vitro reconstitution and x-ray crystallography. Of particular interest are the microtubule +TIP proteins that dynamically localize to microtubule plus ends, communicate with the actin network, regulate microtubule dynamics, capture kinetochores and engage the cell cortex under polarity-based cues.
My primary research area is computational geometry, in which one studies the design and analysis of algorithms for geometric computation. Computational geometry finds application in problems from solid modeling, CAD/CAM, computer graphics, molecular biology, data structuring, and robotics, as well as problems from discrete geometry and topology. Most of my work involves identifying, representing, and exploiting geometric and topological information that permit efficient computation. My current focus is on applications of computational geometry in Molecular Biology and Geographic Information Systems (GIS). Examples of the former include docking and folding problems, and scoring protein structures using Delaunay tetrahedralization.
Our laboratory studies signal transduction systems controlled by heterotrimeric G proteins as well as Ras-related GTPases using a variety of biophysical, biochemical and cellular techniques. Member of the Molecular & Cellular Biophysics Training Program.
We are combining biochemistry and molecular biology to study protein synthesis in mammalian mitochondria. Factors required for the initiation and elongation steps of have been cloned and detailed protein chemistry is being carried out to study their properties. Mutations of several of these proteins are lethal in humans and these mutations are being studied to study the interactions of these factors with ribosomes and the structures of these factors bound to ribosomes are being examined using cryoelectron microscopy. Chemical probing is being used to explore the structures of mitochondrial mRNAs. The tRNAs in mammalian mitochondria are quite unusual and mutations in them can cause human diseases. The underlying defects in these tRNAs are being probed at structural and biochemical levels providing an understanding of how the mutations lead to human disease.
The major area of our research is Biomolecular Informatics, which implies understanding relationships between molecular structures (organic or macromolecular) and their properties (activity or function). We are interested in building validated and predictive quantitative models that relate molecular structure and its biological function using statistical and machine learning approaches. We exploit these models to make verifiable predictions about putative function of untested molecules.
Our vision is to address one of the great remaining and intractable problems in cellular and molecular biology -- that of determining comprehensive and quantitative structures for all cellular and viral RNAs. To this end, we are developing high-throughput RNA structure analysis technologies (called SHAPE) with the goal of making RNA secondary and tertiary structure analysis as straightforward, in principle, as DNA sequencing is today. We then use these tools to understand otherwise daunting problems that play pivotal roles in cellular function. Current projects include (i) RNA folding and protein assembly reactions central to the infectivity and pathogenesis of human viruses and (ii) assembly of large biomedically important ribonucleoprotein complexes inside living cells.
Our work focuses on molecular aspects of androgen receptor regulation of gene expression, which includes coactivator interactions with the androgen receptor and its functional importance in various clinical syndromes.
