Molecular basis of gene deregulation by the oncogenic transcription factor E2A-PBX1
The E2A gene is also involved in a chromosomal translocation that results in the oncogenic transcription factor E2A-PBX1. The two activation domains of E2 (AD1 and AD2) display redundant, independent, and cooperative functions in a cell-dependent manner, at least in part through an interaction with the transcriptional co-activator CBP/p300. The E2A-PBX1:CBP/p300 interaction is critical for oncogenesis. However, a molecular understanding of this interaction and associated function has been lacking. Here, we describe our use of structural biology, biophysical and biochemical approaches, and complementary cell-based assays and mouse studies to characterize the interactions of E2A-PBX1 with CBP/p300, and our ability to disrupt this interaction by an engineered peptide. Our studies are defining the molecular basis for transcriptional activation and oncogenesis by E2A and E2A-PBX1, and serve as a structural foundation for inhibitor design.
11:30-12:30 BioSci Rm. 3110
The living dead: metabolic arrest and the control of biological time
The Storey lab studies the molecular mechanisms and regulatory principles that provide the common basis for animal metabolic arrest. Although not part of the human experience, torpor or dormancy is widespread across the animal kingdom and represents a key survival strategy in the face of daunting environmental challenges. Indeed, strong metabolic rate depression underlies multiple phenomena including estivation, diapause, freezing and anoxia tolerance, anhydrobiosis, and hibernation. Mammalian hibernation has perhaps the greatest relevance to humans as molecular adaptations imparting survival of hibernator organs at low temperatures have numerous medical applications including improvement of the hypothermic preservation of excised organs for transplant, ischemia resistance, and prevention of muscle atrophy. Current research in the Storey lab also focuses on signal transduction and gene expression in multiple systems, including the action of microRNAs as translational regulators, and novel epigenetic mechanisms (histone and DNA modifications). Supported by NSERC.
For more information visit http://kenstoreylab.com/
Biography: Prof. Kenneth B. Storey, Ph.D., F.R.S.C holds the Canada Research Chair in Molecular Physiology. He received a B.Sc. from the University of Calgary and Ph.D. from the University of British Columbia. Ken is an international authority in the field of biochemical adaptation. His lab integrates the tools of enzymology, metabolic biochemistry, protein chemistry, and molecular biology to identify evolved adaptations underpinning amazing animal phenomena including hibernation, estivation, and freeze and anoxia tolerance. Ken is a prolific author and speaker – he has authored over 750 publications and has given hundreds of talks around the world. Among his many tributes Ken was awarded the 2010 Flavelle Medal in Biological Sciences from the Royal Society of Canada, the 2011 Fry Medal from the Canadian Society of Zoologists, and the 2014 CryoBiology Society Medal.
***Note Special Location: BioSci Rm 1103***
Chill susceptible insects: a slow battle against entropy
The timing and severity of the winter season are key predictors of insect distribution and abundance, but we lack an integrative understanding of why chilling causes tissue damage and death in insects. Most insect species are chill susceptible, meaning they enter a cold-induced coma (chill coma) and suffer irreversible chilling injury well before any freezing of their body fluids occurs. I will give a overview of our recent efforts to connect natural variation in chilling tolerance to the capacity of insects to maintain osmotic homeostasis in the cold. Cold-adapted or cold-acclimated flies and crickets can maintain ion balance at low temperatures and survive prolonged cold exposure. By contrast, warm-adapted species or warm-acclimated individuals lose Na+ and water balance when chilled, which causes a progressive rise in extracellular [K+] that depolarizes cell membranes and causes cell death. The gut and Malpighian tubule epithelia of insects are central to the maintenance of whole animal ion and water balance, and appear to play a critical role in the ability to survive chilling. As an example, I will discuss how cold acclimation reduces the tendency for solute leak through the paracellular septate junctions of the Drosophila gut before and during chronic cold stress. This tightening of paracellular pathways appears to primarily be driven by plastic changes in the abundance of several major structural components of the junctions, and is likely to have cascading impacts on metabolism, growth, and development.
11:30-12:30 BioSci Rm. 3110
*** And Free Pizza Meet & Greet after 12:30-1:30 in BioSci 3rd floor lunch room (Rm 3406)
Macrophage activation and fusion on polymeric surfaces in the presence of damage-associated molecular patterns
Synthetic polymers have widespread use in current and emerging biomedical applications, as components of medical devices, tissue engineering scaffolds, drug delivery devices and sensors. However, the success of these applications is dependent on the cellular response to the implanted material. Essentially all materials elicit an inflammatory response following implantation that can have detrimental affects on the performance of the material, including material degradation leading to failure, chronic inflammation at the implant site and poor tissue integration at the material-tissue interface. Protein adsorption from the biomaterial’s local environment is considered a key factor in determining the cellular, and thus overall host response, to implanted materials. While effect of adsorbed proteins derived from blood has been investigated extensively, the role of endogenous danger signals in biomaterial-induced inflammatory responses is not well understood. These damage associated molecular patterns (DAMPs) are released upon tissue injury (e.g. during implant placement) and are known to induce inflammatory responses in macrophages, a key cell type of biomaterial host responses.
The work described here will focus on an in vitro model of macrophage-biomaterial interactions that investigates the adsorption of DAMPs, and subsequent macrophage activation, on polymer surfaces. Using cell lysate as a complex source of DAMPs, we have demonstrated that DAMP-adsorbed surfaces have increased Toll-like receptor (TLR)-2-mediated NF-kB activity and cytokine expression, compared to serum-adsorbed surfaces. Furthermore, we have observed rapid macrophage fusion to form multinucleated giant cells, independent of the addition of fusogenic factors interleukin (IL)-4, IL-13 and interferon (IFN)-g, suggesting the lysate-mediated fusion occurs through a novel fusion mechanism. The research aims to improve our understanding of in vivo material-cell interactions, which will guide the development of novel strategies to control biomaterial host responses current clinical materials and improve the lifespan of current medical implants.
Evolution of subfunctionalization in metabolic genes
Comparative physiology is a field that celebrates novelty, but intermediary metabolism is notoriously conserved, particularly amongst animals. Short-term regulation of existing enzymes can deal with changes in metabolic flux, and cells can produce more or less of the enzymes to deal with longer term changes. Over evolutionary time there is potential for the proteins themselves to change, yet many differences in primary structure are inconsequential. Against this background of conservation, there are examples where whole genome duplications enabled the evolution of functional divergence in paralogous genes/proteins of animals. In this seminar I will discuss examples where paralogous genes/proteins show lineage-specific patterns of subfunctionalization. That is, genes/proteins that may be orthologous in origin have evolved differences in function, with important consequences for the evolution of energy metabolism.
Feeding hungry plants: exploring the role of cell wall-targeted purple acid phosphatases in Arabidopsis phosphate acquisition
Phosphorus (P) is a limiting macronutrient that roots must assimilate from the soil as soluble inorganic phosphate (Pi; H2PO4-). The most abundant P fraction of many soils exists as organic P-monoesters unavailable for root uptake until hydrolyzed by secretory purple acid phosphatases (PAPs). Plant PAPs belong to a relatively large multigene family whose specific functions in P-metabolism are poorly understood. Purification, characterization, and identification (via peptide sequencing) of native PAP isozymes upregulated by Pi-starved suspension cell cultures of Arabidopsis thaliana has been complemented by studies of the corresponding loss-of-function pap mutant seedlings. This approach has pinpointed the predominant Pi-starvation inducible (PSI), cell wall (CW) targeted PAP isozymes (AtPAP12, AtPAP17, AtPAP25, and especially AtPAP26) that appear to facilitate Arabidopsis Pi-acquisition from extracellular P-esters. AtPAP26 is secreted into the CW as a pair of differentially glycosylated ‘glycoforms’ (AtPAP26-CW1 and -CW2). AtPAP26-CW2 is a high mannose glycoform that interacts with a PSI, CW lectin (curculin). This is the first time that glycoforms or a lectin have been implicated in the plant Pi starvation response. The objective of my PhD thesis is to further our understanding of biochemical and functional properties of CW-targeted PAPs of Pi-deprived Arabidopsis, particularly AtPAP26-CW1 and –CW2, as well as AtPAP17, and AtPAP25. Overall, these studies are relevant to applied efforts to bioengineer crops that are more efficient at acquiring and using Pi, urgently needed to reduce the massive overuse of non-renewable and polluting Pi-containing fertilizers in agriculture.
11:30-12:30 BioSci Rm. 3110
Characterizing the calcium dependent regulation of plant myosins
Our lab is primarily interested in understanding how plants use calcium signal transduction to regulate various cellular events. In animal cells, links between calcium signalling and cytoskeletal activity have been well documented. For example, a major component of the animal cytoskeleton is the acto-myosin complex, where myosin motor-domain proteins “walk” processively along actin filaments and function in a range of important events including muscle contraction, chromosomal rearrangements, and many other processes. Calcium signalling is linked to animal myosin function through the binding of the canonical calcium sensor, calmodulin, to myosin neck regions where it functions as part of the ‘lever’ mechanism in myosin walking. In plants, much less in known about the biochemical properties and physiological roles of myosins. Arabidopsis possesses 17 myosin isoforms divisible into two classes based upon predicted structural differences; class VIII and XI. Although these plant myosins have not been well studied, emerging evidence suggests roles in events such as organelle remodeling and movement, gravotropic response, immune response, and cell expansion. Thus, myosins represent an interesting link between cytoskeletal activity and calcium signal transduction in plants. Surprisingly, evidence for an interaction between calmodulin and myosins in plants is not well established. My project aims to explore questions addressing how plant myosins use calcium sensors to regulate their activity. I will outline my research plan and progress to date drawn from a variety of biochemical, genetic, and physiological approaches.
11:30-12:30 BioSci Rm. 3110
Visualizing replication stress in yeast models of genome instability
DNA replication stress can promote genome instability and cancer. We test fission yeast for the effects of DNA replication stress using genetic and high-resolution microscopy methods. We have seen that interesting differences between replication mutant yeast become apparent after S-phase stress is over: the recovery phase post-instability. This suggests that the recovery phase is an important time when cells that survive might be distinguished from cells that die. We are now testing how replication instability caused by cancer chemotherapy drugs is influenced by cellular environment. Yeast is an ideal tool to determine the genetic contributions of drug-sensitivity and resistance that may promote better patient response to chemotherapeutics. Ideally, drug-surviving cells can be identified with biomarkers found during long-term, live-cell imaging.
11:30-12:30 BioSci Rm. 3110
Chromosomes and bytes of code: A computational genomics approach to identify imprinted genes on the human X chromosome
Humans and other mammals have two sets of chromosomes: one set that is maternally inherited; the other, paternally inherited. While most genes are evenly expressed, there are cases where one copy of the gene is favoured over the other. We typically think of this happening as one trait or allele being ‘dominant’ over the other. In the case of genomic imprinting, however, gene expression is determined based on parent of origin, rather than gene sequence. This results in asymmetric expression of alleles for traits inherited maternally vs. paternally. Defects in imprinted genes are responsible for a number of diseases such as: Prader-Willi syndrome, Beckwith-Wiedemann syndrome, and Angelman syndrome. To date, there have been no imprinted genes identified on the human X chromosome. This is mainly due to the experimental limitations, as well as the random X inactivation that occurs in humans. With these restrictions in mind, how do we investigate genomic imprinting on the human X chromosome? Can computers and data mining be used to complement next-gen sequencing and traditional molecular techniques?
11:30-12:30 BioSci Rm. 3110
**Note: Special date, time and place!
Monday, Sept. 26 from 1:30-2:30pm in the 4th floor EEB Lounge
Advancements in Western Blotting Technology: Bio-Rad's Western Workflow delivers more sensitive results, faster at a lower cost
Bio-Rad Western Blot Imager demo after the seminar 2:30-3:30pm in the Monaghan Lab BioSci Rm. 3416