Medical Sciences Commons^™

Chlamydia Trachomatis Subverts Alpha-Actinins To Stabilize Its Inclusion, A. Haines, J. Wesolowski, F. Paumet

Department of Microbiology and Immunology Faculty Papers

Chlamydia trachomatis is the leading cause of sexually transmitted bacterial disease and a global health burden. As an obligate intracellular pathogen, Chlamydia has evolved many strategies to manipulate its host and establish its intracellular niche called the inclusion. C. trachomatis reorganizes the host actin cytoskeleton to form scaffolds around the inclusion and reinforce the growing inclusion membrane. To control the kinetics and formation of actin scaffolds, Chlamydia expresses the effector InaC/CT813, which activates the host GTPase RhoA. Here, we have discovered that InaC stabilizes actin scaffolds through the host actin cross-linking proteins α-actinins 1 and 4. We demonstrate that α-actinins …

The Role Of Actin Associated Sptbn1 Host Factor In Hiv-1 Infection In Microglial Cells, Hannah Matheney

MSU Graduate Theses

Human immunodeficiency virus (HIV) is a chronic illness affecting more than 32.7 million individuals worldwide. The virus infects immune cells, weakening the immune system overtime eventually leading to acquired immunodeficiency syndrome (AIDS) if left untreated. Infection starts with a fusion step, followed by uncoating of the HIV capsid once in the cytoplasm of the cell. HIV uses host cell proteins to complete the infection process, like the actin associated factor, SPTBN1. The Hulme lab has previously shown that SPTBN1 knockdown by siRNA in microglial cells decreased HIV infection and delayed uncoating of HIV. Because fusion is prior to uncoating, it …

Taking Control: Reorganization Of The Host Cytoskeleton By Chlamydia., Jordan Wesolowski, Fabienne Paumet

Department of Microbiology and Immunology Faculty Papers

Both actin and microtubules are major cytoskeletal elements in eukaryotic cells that participate in many cellular processes, including cell division and motility, vesicle and organelle movement, and the maintenance of cell shape. Inside its host cell, the human pathogen Chlamydia trachomatis manipulates the cytoskeleton to promote its survival and enhance its pathogenicity. In particular, Chlamydia induces the drastic rearrangement of both actin and microtubules, which is vital for its entry, inclusion structure and development, and host cell exit. As significant progress in Chlamydia genetics has greatly enhanced our understanding of how this pathogen co-opts the host cytoskeleton, we will discuss …

Chlamydia Hijacks Arf Gtpases To Coordinate Microtubule Posttranslational Modifications And Golgi Complex Positioning., Jordan Wesolowski, Mary M. Weber, Agata Nawrotek, Cheryl A. Dooley, Mike Calderon, Claudette M. St Croix, Ted Hackstadt, Jacqueline Cherfils, Fabienne Paumet

Department of Microbiology and Immunology Faculty Papers

The intracellular bacterium Chlamydia trachomatis develops in a parasitic compartment called the inclusion. Posttranslationally modified microtubules encase the inclusion, controlling the positioning of Golgi complex fragments around the inclusion. The molecular mechanisms by which Chlamydia coopts the host cytoskeleton and the Golgi complex to sustain its infectious compartment are unknown. Here, using a genetically modified Chlamydia strain, we discovered that both posttranslationally modified microtubules and Golgi complex positioning around the inclusion are controlled by the chlamydial inclusion protein CT813/CTL0184/InaC and host ARF GTPases. CT813 recruits ARF1 and ARF4 to the inclusion membrane, where they induce posttranslationally modified microtubules. Similarly, both …

The Effects Of Acetylenic Tricyclic Bis-(Cyano Enone) On Cell Migration, Eddie Chan

Electronic Thesis and Dissertation Repository

Although cancer survival rates have significantly improved over the past few decades, the improvements are primarily due to early diagnosis and inhibiting cancer growth. Limited progress has been made in the treatment of cancer metastasis, which contributes to 90% of cancer related deaths, and therapeutic agents targeting the various aspects of metastasis are lacking. One potential approach is to utilize small pharmacological compounds to inhibit tumour cell motility, as a strategy against tumour cell migration, invasion, and metastasis. The acetylenic tricyclic bis-(cyano enone), TBE-31, has been shown to be a promising chemopreventative compound. However, its effects on cell migration are …

Mrp4-Dependent Regulation Of Fibroblast Migration, Chandrima Sinha

Theses and Dissertations (ETD)

Roles of cyclic nucleotides and cyclic nucleotide-dependent signaling molecules in regulating several signaling pathways including cell migration have long been known. However, the new and revolutionary concept is that it is not just the absence or presence of cyclic nucleotides, but a highly coordinated balance between these molecules regulates cell migration. Multi-drug resistance protein 4 (MRP4), is a member of the large family of ATP binding cassette (ABC) transporter proteins, that localizes to the plasma membrane and functions as a nucleotide efflux transporter and thus plays a pivotal role in the regulation of intracellular cyclic nucleotide dynamics. In our study …

Role Of Anillin In Regulation Of Epithelial Junctions, Gibran Chadha

Theses and Dissertations

Adherens junctions (AJs) and tight junctions (TJs) are characteristic features of differentiated epithelial cells and are critical for regulation of epithelial barriers and cell polarity. Integrity and remodeling of epithelial junctions depend on their interactions with underlying actomyosin cytoskeleton. Anillin is a multifunctional scaffold able to interact with different cytoskeletal proteins including F-actin and Myosin II. This project aimed to investigate roles of anillin in regulating epithelial AJs and TJs. Using A549 human lung epithelial and DU145 human prostate epithelial cells, we demonstrated the anillin depletion-induced loss of AJs and TJs. This was accompanied by disorganization of perijunctional actomyosin belt …

Assembly And Function Of Myosin Ii On Ultraviolet/Ozone Patterned Trimethylchlorosilane Substrates, Hideyo Takatsuki, Madhukar Kolli, Kevin Rice, B. Day, Shinichi Asano, Mashiur Rahman, Yue Zhang, Ryoki Ishikawa, Kazuhiro Kohama, Eric Blough

B. Scott Day

The study of biomolecular motors represents a rapidly and progressing field of nanobiotechnology. Here, we present a simple method for patterning myosin II on a microstructured surface. Our findings indicate that UV/ozone treatment can be used to alter the hydrophobicity of trimethyl-chloro-silane (TMCS) coated glass surfaces, to alter protein binding, and effectively produce localized motor activity. Taken together, these data suggest that photoreactive patterning may be useful for the selective localization of functional myosin II motor tracks.

Assembly And Function Of Myosin Ii On Ultraviolet/Ozone Patterned Trimethylchlorosilane Substrates, Hideyo Takatsuki, Madhukar Kolli, Kevin Rice, B. Day, Shinichi Asano, Mashiur Rahman, Yue Zhang, Ryoki Ishikawa, Kazuhiro Kohama, Eric Blough

Kevin M Rice

The study of biomolecular motors represents a rapidly and progressing field of nanobiotechnology. Here, we present a simple method for patterning myosin II on a microstructured surface. Our findings indicate that UV/ozone treatment can be used to alter the hydrophobicity of trimethyl-chloro-silane (TMCS) coated glass surfaces, to alter protein binding, and effectively produce localized motor activity. Taken together, these data suggest that photoreactive patterning may be useful for the selective localization of functional myosin II motor tracks.

Assembly And Function Of Myosin Ii On Ultraviolet/Ozone Patterned Trimethylchlorosilane Substrates, Hideyo Takatsuki, Madhukar Kolli, Kevin Rice, B. Day, Shinichi Asano, Mashiur Rahman, Yue Zhang, Ryoki Ishikawa, Kazuhiro Kohama, Eric Blough

Eric Blough

The study of biomolecular motors represents a rapidly and progressing field of nanobiotechnology. Here, we present a simple method for patterning myosin II on a microstructured surface. Our findings indicate that UV/ozone treatment can be used to alter the hydrophobicity of trimethyl-chloro-silane (TMCS) coated glass surfaces, to alter protein binding, and effectively produce localized motor activity. Taken together, these data suggest that photoreactive patterning may be useful for the selective localization of functional myosin II motor tracks.

Myosin Ii Regulates Actin Dynamics Critical For Structural Plasticity And Fear Memory Formation, Cristin Gavin

All ETDs from UAB

Dynamic changes to the actin cytoskeleton are required for synaptic plasticity and long-term memory formation. However, the molecular mechanisms that mediate filamentous actin (F-actin) dynamics during both activity-dependent synaptic potentiation and long-term memory encoding are poorly understood. Myosin II motor proteins are highly expressed in actin-rich growth structures in neurons, including dendritic spines. Recent work demonstrates that these molecular machines mobilize F-actin in response to synaptic stimulation and are required for memory encoding in CA1 hippocampus of rodents. The aims of this project were two-fold. First, we sought to establish if myosin II regulates actin filament polymerization necessary for structural …

Glutamatergic Plasticity In Medial Prefrontal Cortex And Ventral Tegmental Area Following Extended-Access Cocaine Self-Administration, Behnam Ghasemzadeh, Preethi Vasudevan, Chad Giles, Anthony Purgianto, Chad Seubert, John R. Mantsch

Biomedical Sciences Faculty Research and Publications

Glutamate signaling in prefrontal cortex and ventral tegmental area plays an important role in the molecular and behavioral plasticity associated with addiction to drugs of abuse. The current study investigated the expression and postsynaptic density redistribution of glutamate receptors and synaptic scaffolding proteins in dorsomedial and ventromedial prefrontal cortex and ventral tegmental area after cocaine self-administration. After 14 days of extended-access (6 h/day) cocaine self-administration, rats were exposed to one of three withdrawal regimen for 10 days. Animals either stayed in home cages (Home), returned to self-administration boxes with the levers withdrawn (Box), or underwent extinction training (Extinction). Extinction training …

Myosin Ii In Hippocampal Synapses: Regulation Of Synaptic Plasticity, Strength And Actin Dynamics By Two Distinct Isoforms, Maria Dolores Rubio

All ETDs from UAB

Cytoskeletal actin filaments underlie dendritic spine plasticity, critical for several forms of learning and memory. Therefore, understanding the mechanisms that regulate actin dynamics is essential to elucidate memory formation pathways. Myosins, a superfamily of actin binding proteins, have emerged as candidates for regulation of actin dynamics in the brain. Several myosin class II isoforms have been identified in brain, but their individual contribution to synaptic activity is still unknown. Based on the finding that myosin IIB regulates actin polymerization in the growth cone of developing neurons and that it is necessary for maintenance of dendritic spine structure, I hypothesized that …

Frazzled And Abelson Interact To Regulate The Actin Cytoskeleton In Drosophila, Bridget Elsa Varughese

Wayne State University Dissertations

Guidance receptors such as Frazzled affect cell shape and motility by directly or indirectly modulating the cytoskeleton. Fra is particularly needed for the formation of the posterior commissures in a developing Drosophila embryo. The cytoplasmic tyrosine kinase, Abelson Kinase (Abl) enhances the loss of commissures observed in fra mutant. Abl physically interacts with Frazzled to help guide commissural axons across the midline. Furthermore, the loss of commissural axons is only seen when the actin dynamics are perturbed. Abl is also known to regulate actin-dependent processes underlying formation of filopodia, microspikes and membrane ruffles. So, we established a Drosophila S2 cell …

Prostaglandin E(2) Is Crucial In The Response Of Podocytes To Fluid Flow Shear Stress., Tarak Srivastava, Ellen T. Mccarthy, Ram Sharma, Patricia A. Cudmore, Mukut Sharma, Mark L. Johnson, Lynda F. Bonewald

Manuscripts, Articles, Book Chapters and Other Papers

Podocytes play a key role in maintaining and modulating the filtration barrier of the glomerulus. Because of their location, podocytes are exposed to mechanical strain in the form of fluid flow shear stress (FFSS). Several human diseases are characterized by glomerular hyperfiltration, such as diabetes mellitus and hypertension. The response of podocytes to FFSS at physiological or pathological levels is not known. We exposed cultured podocytes to FFSS, and studied changes in actin cytoskeleton, prostaglandin E(2) (PGE(2)) production and expression of cyclooxygenase-1 and-2 (COX-1, COX-2). FFSS caused a reduction in transversal F-actin stress filaments and the appearance of cortical actin …

Lim Kinase 1 And Twinstar In Synaptic Plasticity Of Drosophila Motoneurons, James Brian Machamer

All ETDs from UAB

Modification of the actin cytoskeleton is essential for synaptic plasticity, which is believed to underlie the brain's capacity for learning and memory. Regulation of the actin cytoskeleton by LIM Kinases (LIMK1 and LIMK2) and their downstream targets Actin Depolymerization Factor/Cofilin (ADF/Cofilin) in the mouse forebrain modulates dendritic spine morphology, synaptic function, long-term potentiation (LTP), and learning and memory, but appear dispensable for the regulation of most forms of presynaptic plasticity. However, these analyses were performed in mice mutant for single members of these gene families, and thus the interpretation of these results is confounded by potential compensatory activity of homologous …

Neuroadaptations In The Cellular And Postsynaptic Group 1 Metabotropic Glutamate Receptor Mglur5 And Homer Proteins Following Extinction Of Cocaine Self-Administration, M. Behnam Ghasemzadeh, Preethi Vasudevan, Christopher Mueller, Chad Seubert, John R. Mantsch

Biomedical Sciences Faculty Research and Publications

This study examined the role of group1 metabotropic glutamate receptor mGluR5 and associated postsynaptic scaffolding protein Homer1b/c in behavioral plasticity after three withdrawal treatments from cocaine self-administration. Rats self-administered cocaine or saline for 14 days followed by a withdrawal period during which rats underwent extinction training, remained in their home cages, or were placed in the self-administration chambers in the absence of extinction. Subsequently, the tissue level and distribution of proteins in the synaptosomal fraction associated with the postsynaptic density were examined. Cocaine self-administration followed by home cage exposure reduced the mGluR5 protein in nucleus accumbens (NA) shell and dorsolateral …

Tetraspanin Kai1/Cd82 Inhibits Cell Migration-Related Cellular Events Via Reorganizing Actin Network, Wei Liu

Theses and Dissertations (ETD)

To determine how tetraspanin KAI1/CD82, a tumor metastasis suppressor, inhibits cell migration, we assessed which motility-related cellular events are altered by KAI1/CD82 and how KAI1/CD82 regulates these events. We found that KAI1/CD82-overexpressing cancer cells exhibit various morphologies but typically display elongated cellular extensions and a lack of lamellipodia. Live imaging demonstrated that the formation of lamellipodia and retraction of extensions were deficient upon KAI1/CD82 overexpression.

The deficiency in developing motility-related cellular events was accompanied by defects in actin cortical network and stress fiber formations. Notably, actin polymerization was attenuated by KAI1/CD82. Although Rac1 activity was diminished upon KAI1/CD82 expression, Rac1 …

Tyrosine Phosphorylation Of Villin: Effects On Actin Dynamics, Cell Morphology And Cell Migration, Alok Tomar

Theses and Dissertations (ETD)

Cell migration is a key aspect of many normal and abnormal biological processes, including embryonic development, defense against infections, wound healing, and tumor cell metastasis. In this study we demonstrate that an epithelial cell actin-binding protein, villin, plays a crucial role in the process of cell migration. Overexpression of villin in doxycyline-regulated HeLa Tet-off and MDCK Tet-off cells enhanced cell migration. We further demonstrate that tyrosine phosphorylation of villin by c-src is required for villin-induced cell migration. Previously, we identified four tyrosine phosphorylation sites in the amino-terminal domain of villin. I further identified six new sites in the carboxylterminal region …