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Articles 1 - 30 of 55

Full-Text Articles in Cell Biology

Motor Protein Regulation In Mammalian Mitosis, Barbara Mann Jan 2018

Motor Protein Regulation In Mammalian Mitosis, Barbara Mann

Doctoral Dissertations

Developing and maintaining a multicellular organism relies on the fundamental biological process of cell division, which ensures that genetic material is equally segregated between daughter cells. During mitosis, cells completely rearrange their cytoskeleton into a bipolar spindle through the concerted efforts of microtubules, motor proteins, and microtubule-associated proteins, which cells must regulate spatially and temporally to prevent errors such as chromosomal missegregation: a major cause of cancer. Although the mitotic spindle is a validated target for chemotherapy drug resistance and redundant pathways have highlighted the need for new targets. It is therefore important to understand how proteins that help build ...


Identifying Functional Components Of The Endoplasmic Reticulum Quality Control And Degradation Factor Edem1, Lydia Lamriben Jan 2018

Identifying Functional Components Of The Endoplasmic Reticulum Quality Control And Degradation Factor Edem1, Lydia Lamriben

Doctoral Dissertations

The ER Degradation-Enhancing Mannosidase-Like protein 1 (EDEM1) is a critical endoplasmic reticulum (ER) quality control factor involved in identifying and directing non-native proteins to the ER-associated protein degradation (ERAD) pathway. However, its recognition and binding properties have remained enigmatic since its discovery. Here we provide evidence for an additional redox-sensitive interaction between EDEM1 and Z/NHK that requires the presence of the single Cys on the α-1 antitrypsin ERAD clients. Moreover, this Cys-dependent interaction is necessary when the proteins are isolated under stringent detergent conditions, ones in which only strong covalent interactions can be sustained. This interaction is inherent to ...


Mechanism Of Regulation Of Kinesins Eg5 And Kif15 By Tpx2, Sai Keshavan Balchand Jan 2018

Mechanism Of Regulation Of Kinesins Eg5 And Kif15 By Tpx2, Sai Keshavan Balchand

Doctoral Dissertations

Cell division is the fundamental process by which the replicated genetic material is faithfully segregated to form two identical daughter cells. The mitotic spindle is the macromolecular cytoskeletal structure that is built during every round of cell division to successfully separate the duplicated genome equally into the daughter cells. Errors in spindle formation can thus causegenetic aberrations and can potentially lead to cancer. Understanding the mechanisms that govern proper spindle assembly and function is thus important. Eg5 and Kif15 are two important kinesins which play a major role in establishing and maintaining bipolarity of the mitotic spindle. Both Eg5 and ...


Studies Of Dynein Anchoring Protein In Budding Yeast Saccharomyces Cerevisiae, Safia Omer Jan 2018

Studies Of Dynein Anchoring Protein In Budding Yeast Saccharomyces Cerevisiae, Safia Omer

Doctoral Dissertations

Inheritance of equal genomic content is vital for cellular growth and survival. During cell division, the mitotic spindle is built to ensure equal chromosome segregation between dividing cells. Fidelity of segregation is achieved by the precise positioning of the mitotic spindle by force generators located at the cell cortex where they exert pulling on microtubule (MT). Cortical dynein, a minus end directed motor, generates pulling forces via microtubule end-on capture-shrinkage and lateral MT sliding mechanisms. In Saccharomyces cerevisiae, the dynein attachment molecule Num1 interacts with plasma membrane (PM), endoplasmic reticulum (ER), and mitochondria to facilitate spindle positioning across the mother-bud ...


The Interplay Between Polarity Regulators, Calcium, And The Actin Cytoskeleton During Tip Growth, Carlisle Bascom Jr Jan 2018

The Interplay Between Polarity Regulators, Calcium, And The Actin Cytoskeleton During Tip Growth, Carlisle Bascom Jr

Doctoral Dissertations

Plant cell growth is a meticulously regulated process whereby the cell wall is selectively loosened to allow for turgor-pressure driven expansion. The rate of expansion must equal delivery of new material, or the cell will lyse. In many plant cells, this process happens diffusely around the cell. However, a number of plant cells have anisotropic shapes that require exquisite spatial control of secretion. One simple example of anisotropic patterning is tip growth; highly polarized cell expansion utilized by pollen tubes, root hairs, and moss protonemata. Investigating the role various molecules have in tip growth sheds light on how plant cells ...


Clpxp Functions In Caulobacter As A Universal And Species-Specific Protease, Robert Vass Jan 2018

Clpxp Functions In Caulobacter As A Universal And Species-Specific Protease, Robert Vass

Doctoral Dissertations

Proteolysis shapes many aspects of cellular survival, including protein quality control and cellular signaling. Powered proteolysis couples ATP hydrolysis with a degradation force that actively probes and interrogates the protein population. ClpXP, exemplifies a conserved two-part protease system charged with powered proteolysis. This protease exists as a regulatory element (ClpX), and a compartmentalized, self-contained peptidase element (ClpP). In Caulobacter crescentus, ClpXP degradation plays a crucial role maintaining proteins that exhibit proper activity, and also triggers the start of cellular differentiation. Substrate elimination requires shared aspects of the protease from both quality control and precision protein destruction functions. Here, the regulatory ...


The Far C-Terminus Of Tpx2 Contributes To Spindle Morphogenesis, Brett Estes Jan 2017

The Far C-Terminus Of Tpx2 Contributes To Spindle Morphogenesis, Brett Estes

Masters Theses

A cell must build a bipolar mitotic spindle in order to faithfully segregate replicated DNA. To do so, multiple microtubule nucleation pathways are utilized to generate the robust spindle apparatus. TPX2, a microtubule binding protein, holds crucial roles in both the Ran-dependent and Augmin-dependent pathways where microtubules are nucleated near the chromosomes and from pre-existing microtubules. However, the exact role TPX2 plays in branching microtubules is less understood. Here, we explored the effect of truncating the essential TPX2 C-terminal 37 amino acids on Augmin localization and branching microtubule activity. First, we depleted LLC-Pk1 cells of the Augmin subunit HAUS6 and ...


Partial Craniofacial Cartilage Rescue In Ace/Fgf8 Mutants From Compensatory Signaling From The Ventricle Of Danio Rerio, Douglas A. Calenda Ii Jan 2017

Partial Craniofacial Cartilage Rescue In Ace/Fgf8 Mutants From Compensatory Signaling From The Ventricle Of Danio Rerio, Douglas A. Calenda Ii

Masters Theses

Examples of asymmetric organs are found throughout the animal kingdom. Whether it is superficial like the fiddler crab’s claw or within an organism like our visceral organs, asymmetries have repeatedly evolved in nature. However, the genetic and developmental origins for asymmetric organ development remain unclear, especially for superficially paired structures. Within zebrafish, a striking example of asymmetry occurs within the ace/fgf8 mutant. The pharyngeal cartilages of these mutants develop asymmetrically 35% of the time, with more cartilages developing on the left or right side of the head, but the origins of this asymmetry are unknown. A significant proportion ...


Regulated Proteolysis Of Dnaa Coordinates Cell Growth With Stress Signals In Caulobacter Crescentus, Jing Liu Jan 2017

Regulated Proteolysis Of Dnaa Coordinates Cell Growth With Stress Signals In Caulobacter Crescentus, Jing Liu

Doctoral Dissertations

DNA replication is an essential process in all domains of life. Replication must be precisely regulated, especially at the step of initiation. In bacteria, the replication initiator DnaA is regulated by multiple post-translational regulations to ensure timely replication. Caulobacter crescentus has the most strict replication regulation that DNA only replicates once per cell cycle, and proteolysis of DnaA identified in this species is the only irreversible way to inhibit DnaA, suggesting it might be pivotal to restricting DNA replication. However, the responsible protease(s) and mechanism for its degradation remain unclear since its first discovery in 2005. In this thesis ...


Protein-Nanoparticle Co-Engineering: Self-Assembly, Intracellular Protein Delivery, And Crispr/Cas9-Based Gene Editing, Rubul Mout Jan 2017

Protein-Nanoparticle Co-Engineering: Self-Assembly, Intracellular Protein Delivery, And Crispr/Cas9-Based Gene Editing, Rubul Mout

Doctoral Dissertations

Direct cytoplasmic delivery of gene editing nucleases such CRISPR/Cas9 systems and therapeutic proteins provides enormous opportunities in curing human genetic diseases, and assist research in basic cell biology. One approach to attain such a goal is through engineering nanotechnological tools to mimic naturally existing intra- and extracellular protein delivery/transport systems. Nature builds transport systems for proteins and other biomolecules through evolution-derived sophisticated molecular engineering. Inspired by such natural assemblies, I employed molecular engineering approaches to fabricate self-assembled nanostructures to use as intracellular protein delivery tools. Briefly, proteins and gold nanoparticles were co-engineered to carry complementary electrostatic recognition elements ...


Dissecting Molecular Pathways That Ensure Proper Chromosome Segregation And Cell Division, Anna Ye Jan 2017

Dissecting Molecular Pathways That Ensure Proper Chromosome Segregation And Cell Division, Anna Ye

Doctoral Dissertations

Equal segregation of the genome is a prerequisite for cell survival. During cell division the duplicated DNA is compacted into chromosomes and a multi-protein macrostructure, known as the kinetochore (Kt), is assembled on each copy of compacted DNA. Simultaneously, the mitotic spindle, which is made up of microtubules (MTs), is built to facilitate the equal distribution of the chromosomes between the resulting daughter cells. Kinetochores mediate the interaction between the MTs and the chromosomes, properly positioning them for segregation. To ensure that the DNA is equally divided in every cell division, cells have built a surveillance system to detect any ...


The Key Question In Symbiotic Nitrogen Fixation: How Does Host Maintain A Bacterial Symbiont?, Onur Oztas Jan 2017

The Key Question In Symbiotic Nitrogen Fixation: How Does Host Maintain A Bacterial Symbiont?, Onur Oztas

Doctoral Dissertations

The fact that plants cannot use nitrogen in the gaseous form makes them dependent on the levels of usable nitrogen forms in the soil. Legumes overcome nitrogen limitation by entering a symbiotic association with rhizobia, soil bacteria that convert atmospheric nitrogen into usable ammonia. In root nodules, bacteria are internalized by host plant cells inside an intracellular compartment called the symbiosome where they morphologically differentiate into nitrogen-fixing forms by symbiosome-secreted host proteins.

In this project, I explained the host proteins required to maintain bacterial symbionts and described their delivery to the symbiosome. I showed that the SYNTAXIN 132 (SYP132) gene ...


The Role Of The Formin Protein Family In Membrane Dynamics, Petrus Adrianus Cornelis Van Gisbergen Jan 2016

The Role Of The Formin Protein Family In Membrane Dynamics, Petrus Adrianus Cornelis Van Gisbergen

Doctoral Dissertations

Using molecular genetics, and high end imaging techniques, I assessed the function of the formin protein family in the moss Physcomitrella patens. Formins are proteins that can nucleate and elongate actin filaments. P. patens has 9 formins, divided over three classes. I found that a class II formin (For2A) is essential for polarized growth and specifically binds to the phosphoinositide PI(3,5)P2. Additionally, I show that this formin polymerizes actin filaments in vivo. I demonstrated that binding PI(3,5)P2 is essential for formin function.

My work also shows that one of the class I ...


Studies Of Kinetochore Mechanobiology In Drosophila, Stuart Cane Jan 2016

Studies Of Kinetochore Mechanobiology In Drosophila, Stuart Cane

Doctoral Dissertations

Kinetochores are large multiprotein structures through which chromosomes engage with the microtubules of the mitotic spindle. All kinetochore pairs must ultimately adopt a bioriented configuration, with their associated sister chromatids linked to opposite spindle poles and poised to segregate equally between two daughter cells. Erroneous, non-bioriented attachments that are left uncorrected lead to chromosome mis-segregation, producing aneuploid daughter cells with unequal numbers of chromosomes. Before anaphase onset, bioriented attachments are selectively stabilized whereas non-bioriented attachments remain unstable and are eliminated. This error correction process relies heavily on the extent of outer kinetochore phosphorylation by an Aurora B kinase activity centered ...


An In Vivo Study Of Cortical Dynein Dynamics And Its Contribution To Microtubule Sliding In The Midzone, Heather M. Jordan Jan 2016

An In Vivo Study Of Cortical Dynein Dynamics And Its Contribution To Microtubule Sliding In The Midzone, Heather M. Jordan

Masters Theses

In LLC-Pk1 cells, and most cultured mammalian cells, cell division is highly regulated to achieve equal sized daughter cells. During this process, duplicated centrosomes separate and establish a bipolar array called the mitotic spindle. The mitotic spindle is responsible for aligning the chromosomes at the metaphase plate, and separating sister chromatids during anaphase. Spindle positioning and elongation are thought to be driven by the interaction between dynamic astral microtubules and cortical dynein. Extensive research has revealed that dynein is anchored to the cortex via the highly conserved NuMA/LGN/Gαi ternary complex in metaphase and the additional PIP/PIP2/NuMA ...


Mammalian Egg Activation: The Roles Of Trpv3 Channels And Plcz1, Hoi Chang Lee Jan 2016

Mammalian Egg Activation: The Roles Of Trpv3 Channels And Plcz1, Hoi Chang Lee

Doctoral Dissertations

Calcium channels at the plasma membrane have been suggested to mediate Ca2+ influx during egg activation. The transient receptor potential (TRP) Ca2+ channel, TRPV3, is differentially expressed in oocytes during maturation, being fully active at MII stage. Specific stimulation of TRPV3 channels in mouse eggs promotes Ca2+ influx sufficient to induce egg activation and parthenogenesis. In chapter 2, we explore the function and distribution dynamics of the TRPV3 channel protein during oocyte maturation. Using dsRNA, TrpV3 overexpression, and inhibitors of protein synthesis, we modified the native expression of the channel and showed that the TRPV3 protein is ...


The Cellular Context Of Estradiol Regulation In The Zebra Finch Auditory Forebrain, Maaya Ikeda Jan 2016

The Cellular Context Of Estradiol Regulation In The Zebra Finch Auditory Forebrain, Maaya Ikeda

Doctoral Dissertations

Estradiol, traditionally known as a hormone that communicates with distant cells in the body, is also synthesized locally in the brain to act as a neuromodulator. Neuromodulators differ from neurotransmitters in that they simultaneously affect a population of neurons and their actions are not limited to the synapse. One of the many effects of estradiol signaling is rapid modulation of auditory processing in response to external stimuli. The enzyme required for estradiol synthesis, aromatase, is highly expressed in the regions that are involved in higher-order processing of sounds in humans and songbirds. Since zebra finches, a type of songbird, are ...


Cell Adhesion Biophysics On Dynamic Polymer Constructs, Andreas Kourouklis Jan 2015

Cell Adhesion Biophysics On Dynamic Polymer Constructs, Andreas Kourouklis

Doctoral Dissertations

The biophysical characteristics of cell adhesion from single protein to cell length scales have primarily been studied using purely elastic substrates. However, natural extracellular matrix (ECM) is viscoelastic and contains mobile components. In this work, we combined chemistry and cell biology tools to design and characterize laterally mobile viscoelastic polymer films that promote receptor-specific cell adhesion. Moreover, we used amphiphilic block copolymers that are end-labeled with RGD peptide ligands to allow for integrin-mediated cell adhesion. The addition of a trace hydrophobic homopolymer in the supported bilayer block-copolymer films is used to tune the lateral mobility of the films. NIH 3T3 ...


Mimicking The Arterial Microenvironment With Peg-Pc To Investigate The Roles Of Physicochemical Stimuli In Smc Phenotype And Behavior, William G. Herrick Jan 2015

Mimicking The Arterial Microenvironment With Peg-Pc To Investigate The Roles Of Physicochemical Stimuli In Smc Phenotype And Behavior, William G. Herrick

Doctoral Dissertations

The goal of this dissertation was to parse the roles of physical, mechanical and chemical cues in the phenotype plasticity of smooth muscle cells (SMCs) in atherosclerosis. We first developed and characterized a novel synthetic hydrogel with desirable traits for studying mechanotransduction in vitro. This hydrogel, PEG-PC, is a co-polymer of poly(ethylene glycol) and phosphorylcholine with an incredible range of Young’s moduli (~1 kPa - 9 MPa) that enables reproduction of nearly any tissue stiffness, exceptional optical and anti-fouling properties, and support for covalent attachment of extracellular matrix (ECM) proteins. To our knowledge, this combination of mechanical range, low ...


Characterization Of Ca2+ Influx Pathway(S) During Mouse Oocyte Maturation, Banyoon Cheon Sep 2014

Characterization Of Ca2+ Influx Pathway(S) During Mouse Oocyte Maturation, Banyoon Cheon

Doctoral Dissertations

Ca2+ signaling induced at fertilization, also known as oscillations, is essential in mammalian eggs to initiate early embryonic development. The generation of the oscillations relies on optimization of Ca2+ toolkit components during oocyte maturation. In this dissertation, we intend to deepen our understanding of how this differentiation of the Ca2+ toolkit, especially those components associated with Ca2+ influx, is achieved during maturation, and how it contributes to the filling of the ER Ca2+ store during the maturation and fertilization.

We first identified the expression and characterized the function of the components of the Store Operated ...


The Roles Of Myosin Xi And Rop In Moss Tip Growth, Graham M. Burkart May 2014

The Roles Of Myosin Xi And Rop In Moss Tip Growth, Graham M. Burkart

Doctoral Dissertations

Because of the large number of myosin XI and ROP genes found in many angiosperms, it has been difficult to determine their precise role with respect to tip growth. In contrast, there are only two myosin XI genes in four ROP genes in the moss Physcomitrella patens. To determine their role in tip growth using a loss-of-function approach, I used RNA interference (RNAi) and found that both of these proteins are essential for tip growth. Consistent with a role in tip growth, I show that a functional, full-length fusion of mEGFP to myosin XI accumulates at a subcortical, apical region ...


Functional Analysis Of Moss Class Viii Myosin And Its Role In Plant Cell Division, Shu-Zon Wu May 2014

Functional Analysis Of Moss Class Viii Myosin And Its Role In Plant Cell Division, Shu-Zon Wu

Doctoral Dissertations

The moss Physcomitrella patens is a great model system for studying plant gene function using reverse genetic approaches. It undergoes efficient gene-targeting by homologous recombination, allowing the generation of specific gene knockout and tagging a gene at its endogenous locus. Additionally, RNAi is quite effective in P. patens, providing an effective tool for rapid gene silencing and phenotypic characterization. Taking advantage of these features, this dissertation described the establishment of a system to perform an unbiased gene-by-gene RNAi assay to screen for tip growth phenotypes in P. patens. A small set of RNAi constructs were tested, within them one gene ...


The Identification And Characterization Of A Group Of Er Tpr-Containing Adapter Proteins, Johan C. Sunryd Dr. Apr 2014

The Identification And Characterization Of A Group Of Er Tpr-Containing Adapter Proteins, Johan C. Sunryd Dr.

Doctoral Dissertations

The endoplasmic reticulum (ER) is an organelle responsible for a variety of functions in all eukaryotic cells. Some of these functions are localized to specific regions in the ER, such as the ribosome-studded rough ER sheets or the ribosome-free smooth ER sheets. The smooth ER sheets have the ability to form ER tubules, which extend throughout the cell and make contact with other organelles. In order to accommodate these localized functional regions, a certain degree of heterogeneity and compartmentalization into sub-domains exists within the ER. Since the ER membrane and lumen are contiguous, the compartmentalization of the ER into sub-domain ...


The Inflammatory Response To Acute Muscle Injury, Kevin O'Fallon Feb 2014

The Inflammatory Response To Acute Muscle Injury, Kevin O'Fallon

Doctoral Dissertations

The overall goal of this dissertation was to examine inflammatory and regenerative responses to acute skeletal muscle damage and to define molecular mediators of repair. Study I examined the effects of an oral anti-inflammatory supplement on exercise-induced muscle damage (EIMD) and systemic inflammation in a human model. Quercetin has been shown in animal and in vitro models to downregulate nuclear factor-kappa beta (NF-κB) nuclear transactivation and monocyte chemoattractant protein 1 (MCP-1) secretion, which regulate muscle regeneration and inflammatory signaling between muscle and immune cells after injury. Subjects ingested quercetin (N=15) or placebo (N=15) before and after performing 24 ...


Effect Of A 10 Day Decrease In Physical Activity On Circulating Angiogenic Cells, Gayatri Guhanarayan Jan 2014

Effect Of A 10 Day Decrease In Physical Activity On Circulating Angiogenic Cells, Gayatri Guhanarayan

Masters Theses 1911 - February 2014

Circulating angiogenic cells (CACs) are early predictors of cardiovascular health and are inversely proportional to related outcomes. Increased number and function of CACs is seen in healthy individuals compared with individuals with cardiovascular disease (CVD). Exercise increases CAC number and function in CVD populations, through a nitric oxide-mediated mechanism. Inactivity is a growing concern in industrialized nations; it is an independent risk factor for CVD and is linked to increased mortality. The purpose of this study was to understand the effect of reduced physical activity (rPA) on two CAC populations (CFU-Hill and CD34+) in highly active individuals. We examined the ...


Rapid Method Of Processing Sperm For Nucleic Acid Extraction In Clinical Research, Matthew K. De Gannes Jan 2014

Rapid Method Of Processing Sperm For Nucleic Acid Extraction In Clinical Research, Matthew K. De Gannes

Masters Theses

Background: Sperm contain highly compact nuclei, inhibiting DNA extraction using traditional techniques. Current methods extracting sperm DNA involve lengthy lysis and no means of stabilizing DNA, hindering clinical research.

Objective: We sought to optimize an efficient method of extracting high quality human sperm DNA.

Methods: Sperm from three volunteers were isolated using PureCeption. We tested 1) proteinase K with DNA/RNA Shield, 2) DTT and TCEP as reducing agents, 3) QIAshredder homogenization, and 4) stability of sperm DNA fresh (baseline) or after 4 weeks of storage at 4OC in DNA/RNA Shield using modified Quick-gDNA MiniPrep. DNA was ...


The Role Of The Novel Lupus Antigen, Acheron, In Moderating Life And Death Decisions, Ankur Sheel Jan 2014

The Role Of The Novel Lupus Antigen, Acheron, In Moderating Life And Death Decisions, Ankur Sheel

Masters Theses

Programmed cell death (PCD) is a major regulatory mechanism employed during development and homeostasis. The term PCD was coined to describe the death of the intersegmental muscles (ISMs) of moths at the end of metamorphosis. The timing of ISM death in the Tobacco Hawkmoth, Manduca sexta, is regulated by a fall in the titer of the steroid molting hormone 20-hydroxyecdysone (20E) late on day 17of pupal-adult development. This triggers the release of the peptide hormone, Eclosion Hormone (EH), which mediates its effects via the secondary messenger cGMP. It has been previously demonstrated that ISM death requires de novo gene expression ...


The Role Of Ykl-40 In The Progression Of Glioblastoma, Ralph Anthony Francescone Sep 2013

The Role Of Ykl-40 In The Progression Of Glioblastoma, Ralph Anthony Francescone

Open Access Dissertations

Glioblastoma Multiforme (GBM) is the most common brain cancer and one of the most fatal forms of cancer overall. The average survival time is 10-14 months, and less than 10% of patients survive more than 5 years after diagnosis. It is characterized by extreme vasculature, chemo/radioresistance, and invasiveness into the normal brain. The current standard of care, which includes surgical removal of tumor, radiation, and the chemotherapeutic agent temozolomide, initially stunt tumor growth. Nevertheless, the tumor invariably rebounds and the patient succumbs to the disease. Therefore, there is an urgent need to develop new therapies for this devastating disease ...


Effects Of Phytochemicals From Rhodiola Crenulata On Highly Invasive Breast Cancer Cell Lines And Embryonic Models Of Migration, Adaris Rodriguez-Cortes Sep 2013

Effects Of Phytochemicals From Rhodiola Crenulata On Highly Invasive Breast Cancer Cell Lines And Embryonic Models Of Migration, Adaris Rodriguez-Cortes

Open Access Dissertations

The root of the Tibetan plant Rhodiola crenulata is part of eastern traditional medicine. Studies have suggested that members of the Rhodiola genus display anticancer properties. In this study we examine the effect of R. crenulata in a cellular model of invasive breast cancer, this disease being the second cause of cancer death among women in the US. Deregulation of the Wnt/β-catenin pathway has been frequently observed in breast cancers and appears to have a key role in the transformation of benign cells to a malignant form. Although mutations of the Wnt growth factor are rarely observed in cancer ...


Characterizing The Heavy Metal Chelator, Tpen, As A Ca2+ Tool In The Mammalian Oocyte, Robert A. Agreda Mccaughin Jan 2013

Characterizing The Heavy Metal Chelator, Tpen, As A Ca2+ Tool In The Mammalian Oocyte, Robert A. Agreda Mccaughin

Masters Theses 1911 - February 2014

N,N,N’,N’-tetrakis-(2-Pyridylmethyl) ethylenediamine (TPEN) is a heavy metal chelator with high affinity for zinc. TPEN causes important responses in mammalian eggs. For example, these eggs are arrested at the MII stage by the Endogenous Mitotic Inhibitor 2 (Emi2), which prevents activation of the Anaphase Promoting Complex (APC) and degradation of Cyclin B. By chelating zinc, TPEN inactivates Emi2 and eggs undergo spontaneous exit of meiosis and egg activation. TPEN chelates Ca2+ with lower affinity, although in the Endoplasmic Reticulum (ER), where Ca2+ concentrations are high, TPEN may sequester Ca2+ preventing release into the ...