Cell Biology Commons^™

Investigating The Escape Mechanism Of Sre Bearing Mrna Transcripts During Viral Host Shutoff, Daniel Macveigh-Fierro

Doctoral Dissertations

During viral infection, the virus and host clash for control over gene expression in an evolutionarily arms race that has raged for thousands of years. During lytic replication, Kaposi’s sarcoma associated herpesvirus (KSHV) triggers a massive RNA decay event known as host shut off. This causes over 70% of all RNA to be degraded suppressing the host antiviral response while freeing resources for viral replication. Our lab focuses on a subset of transcripts that escape from this viral degradation event using a cis acting 3’ UTR element known as a “SOX resistant element” or SRE. Although we have identified a …

Protein Trafficking In The Endoplasmic Reticulum Mediated By A Tpr-Containing Adapter Protein, Nathan P. Canniff

Doctoral Dissertations

The endoplasmic reticulum (ER) is a large, multifunctional organelle that acts as the entrance into the secretory pathway, which accounts for the folding and maturation of approximately one third of the human proteome. It is the largest organelle in most cell types and is comprised of a single lumen and a contiguous membrane. The ER is responsible for a multitude of roles including protein translocation, folding, maturation, quality control, and glycosylation to name a few. These processes are buoyed by a large collection of chaperones and cochaperones, the largest subfamily of which is characterized by the presence of tetratricopeptide repeat …

Caulobacter Clpxp Adaptor Popa’S Domain Interactions In The Adaptor Hierarchy Of Ctra Degradation, Thomas P. Scudder

Masters Theses

The degradation and recycling of protein is a process essential for the maintenance and regulation of cellular function. More specifically, in Caulobacter crescentus, the ClpXP protease is responsible for driving progression through the cell cycle and protein quality control. This protease utilizes three known adaptors to selectively degrade proteins that initiate different stages of development. This thesis will elaborate on the specific binding interface on one of these adaptors, PopA, with another, RcdA, and focus in on specific residues on PopA and investigate their roles in adaptor binding and delivery of CtrA, the master regulator of Caulobacter. Finally, I …

Principles Of Aaa+ Proteases, Samar Mahmoud

Doctoral Dissertations

ATPases associated with diverse cellular activities (AAA+) proteases in bacteria help maintain protein homeostasis by degrading misfolded and regulatory proteins. While a handful of protein targets for these proteases have been identified in Caulobacter crescentus and other organisms, more research is needed to elucidate mechanisms that govern substrate specificity. In the second chapter of this thesis, I will elaborate on how AAA+ substrate specificity is less rigid than previous work has suggested and how limiting ATP or mutations can alter substrate preferences of the ClpXP protease. In the third chapter, I will highlight our efforts to use a quantitative proteomics …

Characterizing The Multifaceted Roles Of The Proteasomal Deubiquitinase Uch37 In Proteostasis, Heather A. Bisbee

Doctoral Dissertations

Cellular protein pools are maintained through the biological processes of synthesis, degradation and quality control. As the dysregulation of these processes has been implicated in diseases such as neurodegeneration and cancer, understanding their functions is critical for drug development. Modification of proteins with ubiquitin may direct them to the proteasome, a large cellular protease complex, for degradation. Yet, the proteasome contains three deubiquitinating enzymes (DUBs) which remove ubiquitin from proteins, potentially altering their fate. As each DUB recognizes specific ubiquitin linkages and architectures, their activity may regulate how the proteasome handles substrates in dynamic cellular contexts. In this work, we …

Tracking And Modulating Circadian Rhythms In Cell Culture Models, Sujeewa Sampath Lellupitiyage Don

Doctoral Dissertations

Circadian rhythms are 24–hour activity cycles that exist for all organisms, from yeast and bacteria to mammals. Epidemiological data has shown that disruptions to circadian rhythms are associated with various diseases, including cancers. Circadian rhythms are regulated at the cellular level by a "molecular clock,” whose oscillations in protein transcription and translation control a range of downstream pathways. However, the connections between altered rhythms and diseases at the molecular level is unclear. Therefore, in this project, I tracked circadian rhythms in a high-resolution manner and thoroughly analyzed them to more completely reflect circadian behaviors and clock functioning at the molecular …

Utilizing Fluorescence Microscopy To Characterize The Subcellular Distribution Of The Novel Protein Acheron, Varun Sheel

Masters Theses

All cells carry the genetic machinery required to commit cell suicide; a process known as programmed cell death (PCD). While the ability to initiate PCD serves a number of useful purposes during development and homeostasis, misregulation of PCD is the underlying basis of most human diseases, including cancer, autoimmunity disorders and neurodegeneration. Using the tobacco hawkmoth Manduca sexta as a model organism, the Schwartz lab at UMass has demonstrated that PCD requires de novo gene expression and has cloned many death-associated genes. One of these genes encodes a novel protein that was named Acheron after one of the rivers of …

Substrate Selection In Endoplasmic Reticulum Protein Quality Control, Ben Adams

Doctoral Dissertations

Protein folding and maturation is a complex and error-prone process. Errors in this process may lead to deleterious effects ranging from non-functional single proteins to large-scale protein aggregation leading to cell death. It is essential for cellular function that protein misfolding does not occur unchecked, and therefore numerous chaperone systems exist within the cell. For the thousands of proteins which traffic through the secretory pathway, the primary site of folding and maturation is the endoplasmic reticulum (ER). Multiple chaperone pathways within the ER, generally termed ER protein quality control, must support the proper maturation process of these thousands of substrates. …

Investigating Optimal Chemotherapy Options For Osteosarcoma Patients Through A Mathematical Model, Trang M. Le, Sumeyye Su, Leili Shahriyari

Mathematics and Statistics Department Faculty Publication Series

Since all tumors are unique, they may respond differently to the same treatments. Therefore, it is necessary to study their characteristics individually to find their best treatment options. We built a mathematical model for the interactions between the most common chemotherapy drugs and the osteosarcoma microenvironments of three clusters of tumors with unique immune profiles. We then investigated the effects of chemotherapy with different treatment regimens and various treatment start times on the behaviors of immune and cancer cells in each cluster. Saliently, we suggest the optimal drug dosages for the tumors in each cluster. The results show that abundances …

Engineering Stimuli-Responsive Polymeric Nanoassemblies: Rational Designs For Intracellular Delivery Of Biologics, Kingshuk Dutta

Doctoral Dissertations

Biologic drugs have gained enormous research attention in recent years as reflected by the development of multiple candidates to the clinical pipelines and an increased percentage of FDA approval. This is reasoned by the fact that biologics have been proven to deliver more predictive and promising benefits for many hard-to-cure diseases by ‘drugging the undruggable’ targets. However, the challenges associated with biologic drug development are multi-fold, viz, poor encapsulation efficacy, systemic instability, low cellular internalization and endosomal escape capability. Thus, it is essential to develop new molecular strategies that can not only address the associated drug delivery challenges, but also …

Micro-Physiological Models To Mimic Mucosal Barrier Complexity Of The Human Intestine In Vitro, Abhinav Sharma

Doctoral Dissertations

The mucosal barrier in the intestine is vital to maintain selective absorption of nutrients while protecting internal tissues and maintaining symbiotic relationship with luminal microbiota. This bio-barrier consists of a cellular epithelial barrier and an acellular mucus barrier. Secreted mucus regulates barrier function via in situ biochemical and biophysical interaction with luminal content that continually evolves during digestion and absorption. Increasing evidence suggests that a mucus barrier is indispensable to maintain homeostasis in the gastrointestinal tract. However, the importance of mucus barrier is largely underrated for in vitro mucosal tissue modeling. The major gap is the lack of experimental material …

Engineering Mesothelin-Binding Proteins As Targeted Cancer Diagnostics And Therapeutics, Allison Rita Sirois

Doctoral Dissertations

Cancer is a significant global health concern; and traditional therapies, including chemotherapeutics, are often simultaneously toxic yet ineffective. There is a critical need to develop targeted cancer therapeutics which specifically inhibit molecules or molecular pathways essential for tumor growth and maintenance. Furthermore, a targeted therapy is only effective when a patient's tumor expresses the molecular target; therefore, companion diagnostics, including molecular imaging agents, are a necessary counterpart of targeted therapies. Mesothelin (MSLN) is a cell surface protein overexpressed in numerous cancers, including triple-negative breast, pancreatic, ovarian, liver, and lung, with limited expression in normal tissues. Aberrant MSLN expression promotes tumor …

Involvement Of Calcium-Dependent Protein Kinases And Phosphatases In Sperm Capacitation-Associated Events, Bidur Paudel

Doctoral Dissertations

ABSTRACT To acquire fertilizing ability, mammalian sperm undergo a series of biochemical and physiological changes collectively known as capacitation^1,2. At the molecular level, capacitation is associated with a fast bicarbonate (HCO₃^-)-dependent activation of a unique type of soluble adenyl cyclase (sAC) and a consequent increase in cyclic AMP (cAMP) levels and PKA activation³. Activation of a cAMP/PKA pathway results in the phosphorylation of PKA substrates, which in turn initiates activation of several signaling cascades ultimately leading to an increase in phosphorylation on tyrosine residues (P-Tyr) of sperm axonemal proteins^4,5. Increase in …

Cation Channels, Ca2+ Homeostasis, And Fertility In The Mouse, Goli Ardestani

Doctoral Dissertations

In mammals, fully grown immature oocytes, also known as germinal vesicle (GV), are arrested at prophase of meiosis I. Upon increase of the luteinizing hormone (LH), GV oocytes resume meiosis and reach the metaphase II (MII) stage of the second meiosis, a process known as oocyte maturation. These mature oocytes, henceforth referred to as eggs, are ovulated arrested at the MII stage, from which they are released at the time of fertilization. As in many other cells, Ca²⁺ homeostasis plays a pivotal role in oocytes during maturation and following fertilization, and it is therefore carefully regulated in these cells. …

Tpr-Containing Proteins Control Protein Organization And Homeostasis For The Endoplasmic Reticulum, Jill Bradley-Graham

Doctoral Dissertations

The endoplasmic reticulum (ER) is a complex, multifunctional organelle comprised of a continuous membrane and lumen that is organized into several functional regions. It plays various roles including protein translocation, folding, quality control, secretion, calcium signaling, and lipid biogenesis. Cellular protein homeostasis is maintained by a complicated chaperone network, and the largest functional family within this network consists of proteins containing tetratricopeptide repeats (TPRs). TPRs are well-studied structural motifs that mediate intermolecular protein-protein interactions, supporting interactions with a wide range of ligands or substrates. Nine TPR-containing proteins have been shown to localize to the ER and control protein organization and …

De-Coding The Impact Of Evolved Changes In Gene Expression And Cellular Phenotype On Primate Evolution, Trisha Zintel

Doctoral Dissertations

The goal of the dissertation work outlined here was to investigate the influence of proximal processes contributing to evolutionary differences in phenotypes among primate species. There are numerous previous comparative analyses of gene expression between primate brain regions. However, primate brain tissue samples are relatively rare, and my results have contributed to the pre-existing data on more well-studied primates (i.e. humans, chimpanzees, macaques, marmosets) as well as produced information on more rarely-studied primates (i.e. patas monkey, siamang, spider monkey). Additionally, the primary visual cortex has not previously been as extensively studied at the level of gene expression as other brain …

From Soap Bubbles To Cell Membranes, Peter Beltramo

Science and Engineering Saturday Seminars

Have you ever blown a soap bubble and wondered - what causes the bubble to be so stable and produces those colorful reflections of light? The answer lies in a class of molecules known as surfactants, and they have remarkable similarities with the molecules that comprise the cell membrane of all living organisms. In this workshop, we will use the analogy of a soap bubble to describe cellular membrane properties such as chemistry, structure, membrane transport, and ion channel formation. The goals of this workshop are to 1) link initially intractable concepts in biology like intracellular transport to the intuitive …

Environmental Risk Factors For Inflammatory Bowel Disease: Triclosan And Other Consumer Antimicrobials, Katherine Z. Sanidad

Doctoral Dissertations

Inflammatory bowel disease (IBD) has become a serious health problem since the incidence and prevalence of IBD has dramatically increased throughout the world. There is evidence that environmental factors are primarily responsible for the increase of IBD, therefore, it is important to identify novel environmental risk factors to reduce the risk of IBD and its associated diseases. Antimicrobials used in consumer products might serve as environmental risk factors for IBD and its associated diseases. Triclosan (TCS), triclocarban (TCC), benzalkonium chloride (BAC), benzethonium chloride (BET), and chloroxylenol (PCMX) are widely used antimicrobial ingredients in consumer products and are ubiquitous contaminants in …

Investigating The Role Of Lbh During Early Embryonic Development In Xenopus Laevis, Emma Weir

Masters Theses

LBH is a highly conserved protein whose role during vertebrate development is relatively under-studied. In collaboration with the Albertson lab, our lab has previously shown that it is necessary for cranial neural crest cell migration in the zebrafish and in Xenopus laevis. The molecular mechanisms through which it acts are not well understood.

In Xenopus, LBH is a maternally deposited protein. As such, studying its role in early development has not been feasible through the morpholino-mediated knockdown techniques that prevent translation of target genes. Recently, a technique for degrading endogenous proteins was developed, called Trim-Away. This was developed in mammalian …

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 …

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 the …

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 …

Characterization Of She1 Spindle Role Using Ceullular, Biochemical, And Biophysical Methods, Yili Zhu

Doctoral Dissertations

During development, metaphase spindles undergo large movement and/or rotation to determine the cell division axis. While it has been shown that spindle translocation is achieved by astral microtubules pulling and/or pushing the cortex, how metaphase spindle stability is maintained during translocation remains not fully understood. In budding yeast, our lab has previously proposed a model for spindle orientation wherein the mitotic spindle protein She1 promotes spindle translocation across the bud neck by polarizing cortical dynein pulling activity on the astral microtubules. Intriguingly, She1 exhibits dominant spindle localization throughout the cell cycle. However, whether She1 has any additional role on the …

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 …

Examining Shsp-Substrate Capture And Chaperone Network Coordination Through Cross-Linking, Keith Ballard

Doctoral Dissertations

Small heat shock proteins (sHSPs) and related α-crystallins are virtually ubiquitous, ATP-independent molecular chaperones linked to protein misfolding diseases. They comprise a conserved core α-crystallin domain (ACD) flanked by an evolutionarily variable N-terminal domain (NTD) and semi-conserved C-terminal extension/domain (CTD). They are capable of binding up to an equal mass of unfolding protein, forming large, heterogeneous sHSP-substrate complexes that coordinate with ATP-dependent chaperones for refolding. To derive common features of sHSP-substrate recognition, I compared the chaperone activity and specific sHSP-substrate interaction sites for three different sHSPs from Arabidopsis (At17.6B), pea (Ps18.1) and wheat (Ta16.9), for which the atomic solution-state structures …

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 …

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 …

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 …

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. When these …

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, I …