CSB Seminar: Prof. Zhonglin Mou, Microbiology and Cell Science, University of Florida

CSB Departmental Seminar

Prof. Zhonglin Mou
Microbiology and Cell Science
University of Florida

“Function of Extracellular NAD(P) in Plant Immunity”

Abstract:

Emerging evidence from research in mammalian cells has indicated that cellular NAD(P) can be actively or passively released into the extracellular compartment (ECC), where NAD(P) is processed or perceived by ectoenzymes or cell-surface receptors/channels, leading to transmembrane signaling. Surprisingly, no homologous proteins of mammalian ectoenzymes have been identified in plants, which calls into question whether extracellular NAD(P) [eNAD(P)] and eNAD(P)-activated signaling pathways exist in plants. We found that exogenous application of NAD(P) induces immune responses without changing intracellular NAD(P) homeostasis in Arabidopsis, suggesting that NAD(P) may function in the ECC of plant cells. Moreover, during pathogen infection, cellular NAD(P) is released into the ECC and the amount of NAD(P) released is sufficient for activating immune responses in Arabidopsis. These data suggest that eNAD(P) may act as an endogenous elicitor in plant immune response. Supporting this hypothesis, the well-characterized human NAD(P)-metabolizing ectoenzyme CD38, when expressed in Arabidopsis, suppresses eNAD⁺-induced defense gene expression and disease resistance, indicating that the mechanisms used by plants to process or perceive eNAD(P) for immune response activation may not be the same as those in mammalian cells. Presently eNAD(P)-activated signaling networks in plants remain undefined and how eNAD(P) is processed or perceived by plant cells is unknown. We are addressing these questions through microarray and genetic experiments. Results of these experiments and possible plant cell-surface targets/receptors of eNAD(P) will be discussed.

Host: Keiko Yoshioka

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CSB Seminar: Prof. Mark Peifer, Biology Department, University of North Carolina at Chapel Hill

CSB Departmental Seminar

Prof. Mark Peifer

Biology Department

University of North Carolina at Chapel Hill

"Cytoskeletal Regulation from Molecules to Morphogenesis"

Abstract:

Actin regulators are essential for the cell shape changes and protrusive behaviors required for cell motility, morphogenesis, and cancer metastasis. While many key actin regulators have been identified and individually characterized in vitro and single cell contexts, critical questions remain about how they work in parallel and together to generate the diverse array of actin structures seen in vivo during normal development. Among the most critical actin-based structures driving development and homeostasis are the dynamic combinations of lamellipodia and filopodia characterizing different cell types. We use Diaphanous-class formins (Dia) and Enabled/VASP (Ena) proteins as models to address these fundamental questions. Both associate with actin filament barbed ends and promote actin polymerization. We have taken an interdisciplinary approach to attack this problem at a number of different scales, combining single molecule imaging, computational analysis of cell protrusive behavior in cell culture, and analysis of cell migration during normal embryonic development. These studies reveal how the different biochemical properties of Enabled and Diaphanous allow them to drive distinctive protrusive behaviors, reveal how their physical interaction with one another modifies this, and reveal how different cells in vivo use different combinations of regulators to drive their unique suites of cell protrusions.

Host: Prof. Dorothea Godt

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CSB Departmental Seminar: Gilles Hickson, Université de Montréal, "Cytokinesis: Scaffolding the Contractile Ring .... and Beyond"

Prof. Gilles Hickson
Sainte-Justine Hospital Research Centre and
Dept Pathology & Cell Biology
Université de Montréal

"Cytokinesis: Scaffolding the Contractile Ring .... and Beyond"

Host: Prof. Tony Harris

Video Conferencing at UTM (DV 4001) & UTSc (MW 229)

Abstract:

Cytokinesis of all animal cells involves dramatic changes in cell shape typified by assembly of an equatorial actin-, myosin- and septin-based contractile ring (CR). After closure of this ring, sister cells remain connected by an intercellular bridge, comprising a microtubule-based midbody encircled by a cortical midbody ring (MR) that mature together in poorly understood ways until abscission completes cytokinesis. Traditionally, the CR, MR and abscission stages have been considered separately. However, our recent work in Drosophila cells suggest that they represent a continuum, sharing a common machinery that evolves as cytokinesis progresses. The multi-domain scaffold protein, Anillin, is at the hub of this machinery, capable of integrating many other components. We are working towards deciphering how Anillin and its interactors coordinate cytokinetic progression. This will help us to understand how cells ordinarily execute cytokinesis with extreme fidelity, how the machinery is adapted to suit the needs of different developmental contexts, and how the machinery may be hijacked and/or targeted during cancer development.

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CSB Departmental Seminar: Eric Xu - Exploring Hormone Receptor Structures for Signalling Mechanism and Drug Discovery

Dr. H. Eric Xu
Laboratory of Structural Sciences
Van Andel Research Insitute
Grand Rapids, MI

Exploring Hormone Receptor Structures for Signalling Mechanism and Drug Discovery

Friday, October 3, 2014 at 2 p.m.
Ramsay Wright Building, Room 432

Host: Prof. Peter McCourt

Video Conferencing at UTM (DV 4001) & UTSc (MW 229)
Abstract:
Hormones are efficient messengers for cell-cell communications and
regulate diverse and important physiology processes in both animals
and plants. Our lab has been focused on structural studies of hormone
receptors in both plants (abscisic acid, strigolactones) and animals (GRCRs)
with a hope to uncovering fundamental signaling mechanisms. Since,
modulation of hormone signalling by pharmaceutical agents constitute
a large portion of modern drug discovery research we specifically use our
structural analysis for drug design and discovery.

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CSB Departmental Seminar: Peter Roy, University of Toronto

Professor Peter Roy

Department of Molecular Genetics
University of Toronto

"Seeing the Beacon in the Storm: The EVA-1-Co-Receptor Enables UNC-40/DCC to Respond to a Localized Guidance Cue at the Expense of the more Globally-Distributed UNC-6/Netrin CUE"

Friday, September 26, 2014 at 2 p.m.
Ramsay Wright Building, Room 432

Host: Prof. Maurice Ringuette
Video Conferencing at UTM (DV 4001) & UTSc (MW 229)

Abstract:

During animal development, cells and cell extensions migrate along stereotypical paths to their target destination by interacting with guidance cues in their environment. The guidance receptors on the surface of these cells can each interact with several different cues, and many of the cues can each interact with multiple receptors. How a migrating cell can reach its target amid this apparent receptor-cue promiscuity is poorly understood. Here, we extend our earlier investigation of how the UNC-40 receptor, which is known to interact with the UNC-6 guidance cue, mediates attraction towards the MADD-4 guidance cue. We show that another transmembrane protein called EVA-1 increases the sensitivity of UNC-40 to MADD-4. This increase in sensitivity allows UNC-40 to respond to MADD-4 in the presence of UNC-6. Without EVA-1, UNC-6 dominates UNC-40 function and restricts its response to MADD-4. Hence, the presence of EVA-1 acts like a switch to change UNC-40’s sensitivity from UNC-6 to MADD-4, and in turn allows UNC-40-expressing cells to migrate towards the source of MADD-4 within a field of the UNC-6 guidance cue.

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