Cell Biology and Cellular Dynamics
Eukaryotic cells are amazing machines that integrate information at multiple levels to rapidly adapt and respond to their enviroments, to coordinate efforts and communicate with their neighbors in tissues and organs, and to migrate or proliferate during development and disease. Cells employ a vast battery of proteins and protein complexes, as well as membrane-associated proteins, to achieve these sensory mechanisms and to transduce signals into action. Typical examples of coordination between signals and cellular dynamics include cell crawling, shape changes and response to potential pathogens. Biological mechanisms that underpin these cellular dynamics occur at multiple levels, from genesis of cell shape by rearranging the cortical cytoplasm, to assembling protein complexes that choreograph membrane budding and trafficking, to transport of small molecules and fluxes in signaling cascades.
In the Dept. of Biological Sciences, researchers in this area investigate: the role of the dynamic cytoskeleton during cellular morphogenesis and motility; signaling cascades involved in cancer and cell differentiation; cell size control; import of protein-nucleic acid complexes into the nucleus; deposition and organization of polysaccharides during cell wall biogenesis; protein and membrane trafficking to and from the plasma membrane; and response of cells to pathogens. These groups train numerous Ph.D. students and post-doctoral scientists, and host visits from international scholars on a regular basis. Student’s training in a cellular dynamics lab will take advantage of state-of-the-art imaging modalities, advance biochemical, proteomics and biophysical approaches; and, forward or reverse-genetic approaches in diverse model organisms. The investigators’ labs are well equipped for innovative, cutting-edge research and are supplemented by facilities provided in the Purdue Center for Cancer Research, The Life Sciences Imaging Facility and the Bindley Bioscience Center. Research in the area is supported by individual investigator and collaborative, interdisciplinary grants from agencies like the NIH, NSF, DOE and BARD.
Aguilar, Claudio
It is well established that the processes of endocytosis and signaling are functionally linked. In fact, our laboratory established that endocytic proteins can directly activate signaling pathways involved in cell polarity and cytoskeleton remodeling.
Currently, our research is focused on the role played by the endocytic machinery in the activation of signaling pathways related to cancer cell invasion and developmental diseases. We are particularly interested in the mechanisms controlling cell migration and spreading.
In order to pursue our research goals we use genetic, biochemical and cell biological techniques in yeast and mammalian cells. We study protein-protein interactions by using biophysical, biochemical and genetic tools. We also investigate the physiological relevance of these interactions in live cells by combining siRNA-mediated knock-down, functional assays (e.g., cell migration and invasion), time-lapse microscopy and Fluorescence Resonance Energy Transfer.
Chang, Henry
Our research interest is to understand how membrane trafficking affects animal development. Specifically, we use Drosophila as the model organism to examine two processes: 1) The activation of Notch signaling by ligand internalization, and 2) The formation of the plasma membrane during sperm formation by the clathrin-mediated transport. Our main strategy is to identify and analyze genes participating in these events. By doing so, we can understand how these genes influence cell fate decision and cellular morphogenesis through membrane dynamics. Our experimental approaches include Drosophila genetics, molecular genetics, immunohistochemistry, fluorescent imaging, and electron microscopy.
Gelvin, Stanton
Our research investigates how a soil bacterium, Agrobacterium tumefaciens, genetically engineers plants. Agrobacterium transfers a piece of bacterial DNA, the T-(transferred) DNA, to wounded plant cells where it makes its way through the cytoplasm to the nucleus. Once in the nucleus, T-DNA integrates into the host genome and expresses genes. Under normal circumstances, these genes cause the tumorous disease Crown Gall on plants. However, scientists have learned to manipulate T-DNA, replacing disease genes with genes of benefit to the plant. Many genetically engineered crop plants with desirable traits (disease resistance, herbicide tolerance, and enhanced nutritional value) were generated using Agrobacterium. Our laboratory investigates the role of plant genes and proteins in this natural genetic engineering process. We have identified plant genes involved in bacterial attachment to plant cells, T-DNA and Virulence protein transfer to and cytoplasmic trafficking within plants, T-DNA nuclear targeting, and T-DNA integration. Recently, we have been able to manipulate some of these plant genes to improve Agrobacterium transformation efficiency. We are currently working with agricultural biotechnology companies to improve the genetic engineering of crops.
Hollenbeck, Peter
My laboratory is interested in long-distance transport within nerve cells. We are particularly interested in how these cells redistribute their mitochondria and how the process goes awry in neurodegenerative diseases. To observe and perturb nerve cells directly, we remove them from the nervous system of chick or Drosophila embryos and induce them to grow in vitro, where we can study the responses of intracellular transport to specific molecular events using computer-enhanced light microscopy. We also measure organelle motility within nerve axons in vivo in Drosophila larvae using confocal microscopy. We have gained insight into how mitochondria are moved, how cell signaling directs them to the right part of the axon at the right time, and how their activity and replication are regulated across time and distance.
Kirshner, Julia
The long-term research objective of my lab is to answer the fundamental questions in cancer stem cell biology. My lab is actively investigating the role of tissue microenvironment in maintaining the balance between self-renewal and differentiation of cancer stem cells. Our working hypothesis is that cancer stem cells are found in a specialized microenvironment niche which keeps the cells in a non-proliferative and drug-resistant state. Altering the conditions in favor of differentiation and proliferation leads to tumor re-growth.
To answer these questions we use tissue culture and in vivo approaches; using 3-dimensional tissue culture models to reconstruct human tissues in vitro and humanized mouse models to recapitulate the human microenvironment in an animal.
If you are interested in more information about current research projects, please visit the lab website at http://kirshner.bio.purdue.edu/
Konieczny, Stephen
Our laboratory is interested in defining the molecular mechanisms by which epithelial cells attain normal apical-basal polarity. We study pancreatic acinar cells which are the major cell population in the pancreas. These cells are responsible for synthesizing and secreting vast quantities of digestive enzymes that are needed by the intestines. Loss of cellular polarity can lead to several pancreatic disease states including pancreatitis and pancreatic cancer. Using a number of different transgenic mouse models, we induce disorganization or reorganization of cellular polarity within pancreatic acinar cells. Affy microarrays, ChIPSeq, and Chip-on-Chip assays, along with confocal microscopy, are employed to identify the key genes involved in this important biological process. Our long-term goals are to define the events required to maintain normal cellular polarity and function so that appropriate therapeutic strategies can be exploited to successfully treat patients with pancreatitis and pancreatic cancer.
Luo, Zhao-Qing
Our laboratory is interested in understanding the cellular and molecular mechanisms that allow microbial pathogens to survive and multiply within the hostile host cells. We use Legionella pneumophila, the causative agent of Legionnaires disease as a model organism. This bacterium is a facultative intracellular pathogen capable of growing in a vacuole within macrophages as well as fresh water amoebae. After uptake, the Legionella-containing vacuole (LCV) in its early phase evades fusion with the lysosomal network and later is transformed into a compartment with characteristics of rough endoplasmic reticulum. Biogenesis of this replicative vacuole requires the Dot/Icm Type IV secretion system that injects hundreds of effector proteins into target host cells. Our current focus is to analyze biochemical and cell biological activities conferred by these proteins and their roles in promoting the unique trafficking of the Legionella-containing vacuole in phagocytic cells. In particular, we are interested in identification of host proteins whose activities are modulated by substrates of the Dot/Icm system and how such modulation contributes to successful intracellular bacterial growth. The long term goal of these studies is to elucidate the molecular mechanisms underlying how this bacterium subverts host signal transduction pathways to establish a successful infection, such information will be invaluable in combating diseases caused by Legionella and other vacuolar pathogens.
Mattoo, Seema
(Biochemistry, Signal Transduction, and Microbiology) Investigation of Fic domain containing proteins in Cellular Signaling.
Mizukami, Yukiko
A fundamental question in cell biology that our laboratory addresses is “what is the relation between cell size and architecture or cellular dynamics in multicellular organisms?” To this end, we have been investigating the connection between cell size, intracellular organization (e.g., cytoskeletal & organelle organizations), and cellular activity (e.g., inner membrane dynamics). Currently, our research focuses on cell size-dependent dynamics of the Arabidopsis COPII cage complex, which plays a key role in protein trafficking from the ER to the Golgi apparatus.
Ready, Don
Our laboratory seeks to understand mechanisms of the cytoskeleton and membrane transport in the development and maintenance of healthy photoreceptors. We apply genetic, molecular and cellular methods to Drosophila photoreceptors, a powerful model system, to conduct in vivo functional assays of genes and proteins essential for normal photoreceptor physiology and development. Recent work in the lab has focused on Rab11 and Myosin V in rhodopsin transport, calcium regulation of Myosin V motility, Arrestin translocation and the unfolded protein response.
Staiger, Chris
The cytoskeleton comprises a dynamic network of polymers that constantly rearranges to achieve a multitude of functions, like cell migration, intracellular motility and cellular morphogenesis. Defects or upregulation of the cytoskeleton are implicated in deafness, metastases of cancer cells and a host of other diseases. The regulation of turnover in cells obviously requires a plethora of associated proteins, but the exact mechanisms are poorly understood. The Staiger lab is interested in how the actin cytoskeleton participates in fundamental cellular responses in plants and transduces signals into changes in cellular architecture. We use state-of-the-art biophysical approaches, advanced imaging modalities, reconstituted biomimetic systems and reverse-genetics to dissect actin dynamics and the function of actin-binding proteins. In particular, we are using variable-angle epifluorescence (VAEM) and total internal reflection fluorescence (TIRFM) microscopy to examine single actin filaments in vivo and in vitro. This has allowed us to generate and test a model for actin turnover called "stochastic dynamics" that differs significantly from current textbook models. We are also examining the crosstalk between the actin cytoskeleton and a bacterial phytopathogen, Pseudomonas syringae, as well as the role of the cortical cytoskeleton in cell wall deposition and organelle motility.
Suter, Daniel
Directional cellular movements are critical in normal physiology and pathophysiology, such as the extension of axons or migration of immune cells to site of infections. Cell motility is a highly dynamic process requiring the integration of extracellular cue sensing, signaling and cytoskeletal dynamics. We use the large growth cones of Aplysia neurons to study this process. They are excellent for quantitative analysis of protein dynamics using various fluorescent imaging approaches including Fluorescent Speckle Microscopy (FSM) and Fluorescence Resonance Energy Transfer (FRET). Protein functions are investigated via molecular, pharmacological and biophysical approaches. We hope that our work will not only improve our understanding of directional cellular movements but also impact the development of therapeutics for pathophysiological conditions, such as neurodegeneration and cancer.
Szymanski, Dan
My lab provides new knowledge about how plant cells integrate central carbon metabolism with cell signaling and growth control.
Taparowsky, BJ
Intracellular signaling pathways culminate in changes in the activity of transcription factors that, in turn, activate or repress genes whose protein products direct cells to proliferate, to differentiate or to undergo programmed cell death. Our laboratory studies the AP-1 transcription factor complex which functions downstream of all major signaling pathways in mammalian cells and is a frequent target of mutations associated with disease. In particular, we study a group of tissue-specific AP-1 proteins - the Batf proteins - which are induced by cellular signaling pathways in hematopoietic cells and function to modulate AP-1 transcriptional activity. Understanding the molecular details of Batf protein function and regulation will shed light on potential approaches that may be used to control AP-1 activity other cellular contexts.
Zhou, Daoguo
My research focuses on the cell biology of infectious diseases, in particular human intestinal diseases caused by pathogenic Salmonella and E. coli. These pathogens cause intestinal diarrhea and may lead to more serious systematic infections in humans. Both pathogenic Salmonella and E. coli utilize the type III protein secretion/translocation system (TTSS) to inject bacterial "effector proteins" into host cells to exploit host cell functions to survive in the hostile environment and cause inflammatory responses. We aim to understand the molecular and cellular mechanism of how these effectors function to enable the pathogens to circumvent our host immune system to cause diseases. We currently have projects studying the role(s) of actin dynamics in Salmonella and E. coli infections and how bacterial effectors exploit the host ubiquitination pathways to induce inflammatory responses.