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Full-Text Articles in Cell Biology

Identification Of Deubiquitinating Enzymes That Control The Cell Cycle In Saccharomyces Cerevisiae, Claudine E. Mapa Nov 2018

Identification Of Deubiquitinating Enzymes That Control The Cell Cycle In Saccharomyces Cerevisiae, Claudine E. Mapa

GSBS Dissertations and Theses

A large fraction of the proteome displays cell cycle-dependent expression, which is important for cells to accurately grow and divide. Cyclical protein expression requires protein degradation via the ubiquitin proteasome system (UPS), and several ubiquitin ligases (E3) have established roles in this regulation. Less is understood about the roles of deubiquitinating enzymes (DUB), which antagonize E3 activity. A few DUBs have been shown to interact with and deubiquitinate cell cycle-regulatory E3s and their protein substrates, suggesting DUBs play key roles in cell cycle control. However, in vitro studies and characterization of individual DUB deletion strains in yeast suggest that these ...


Understanding Nuage-Mitochondrial Coupling In Drosophila Pirna Biogenesis, Tianfang Ge Aug 2018

Understanding Nuage-Mitochondrial Coupling In Drosophila Pirna Biogenesis, Tianfang Ge

GSBS Dissertations and Theses

In the Drosophilaovary, PIWI-interacting RNAs (piRNAs) suppress transposon expression, ensuring female fertility. PIWI proteins Aub and Ago3, loaded with ping-pong piRNAs and reside in perinuclear nuage granules, engage in reciprocal transposon transcript cleavage termed the ping-pong cycle. The other PIWI protein Piwi, loaded with phased piRNAs and resides in the nucleus, silences transposon transcriptionally. Ping-pong piRNAs are made through the ping-pong amplification loop by Aub and Ago3, whereas phased piRNAs are made through consecutive endonucleolytic cleavages that spread in 5′-to-3′ direction, presumably by Zucchini (Zuc), an endonuclease resides on the surface of mitochondria. The ping-pong and phasing biogenesis ...


Maelstrom Represses Canonical Rna Polymerase Ii Transcription In Drosophila Dual-Strand Pirna Clusters, Timothy H. Chang Apr 2018

Maelstrom Represses Canonical Rna Polymerase Ii Transcription In Drosophila Dual-Strand Pirna Clusters, Timothy H. Chang

GSBS Dissertations and Theses

Transposons constitute much of the animal genome. While many transposons are ancient and inactivated, numerous others are intact and must be actively repressed. Uncontrolled transposons can cause genomic instability through DNA damage or mutations and must be carefully silenced in the germline or risk sterility or mutations that are passed on to offspring.

In Drosophila melanogaster, 23–30 nt long piRNAs direct transposon silencing by serving as guides for Aubergine, Argonaute3, and Piwi, the three fly PIWI proteins. piRNAs derive from piRNA clusters—large heterochromatic DNA loci comprising transposons and transposon fragments. piRNAs are loaded into PIWI proteins via the ...


Understanding Multiple Independent Functions Of The Tip60 Acetyltransferase In Embryonic Development, Diwash Acharya Dec 2017

Understanding Multiple Independent Functions Of The Tip60 Acetyltransferase In Embryonic Development, Diwash Acharya

GSBS Dissertations and Theses

Chromatin is a dynamic structure, and chromatin remodeling enzymes regulate chromatin structure to control gene expression and proper lineage specification. Tip60-p400 is a multi-subunit chromatin remodeling complex containing two biochemical activities: the Tip60 subunit is a lysine acetyltransferase (KAT) that targets histones and non-histone proteins, and p400 catalyzes ATP-dependent incorporation of histone variant H2AZ into chromatin. Both of these chromatin modifications have been widely studied with respect to gene expression, DNA damage repair, and apoptosis. Ablation of these catalytic subunits causes defects in normal embryonic development, ESC self-renewal, and gene expression. My goal has been to understand the multiple independent ...


Investigating Structural And Functional Defects In Als-Causing Profilin 1 Variants, Sivakumar Boopathy Sep 2017

Investigating Structural And Functional Defects In Als-Causing Profilin 1 Variants, Sivakumar Boopathy

GSBS Dissertations and Theses

Mutations in profilin 1 (PFN1) cause amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease that targets motor neurons. PFN1 is a 15 kDa protein that is best known for its role in actin dynamics. However, little is known about the pathological mechanisms of PFN1 in ALS. In this dissertation, it is demonstrated that certain familial ALS-linked mutations severely destabilize the native conformation of PFN1 in vitro and cause accelerated turnover of the PFN1 protein in neuronal cells. This mutation-induced destabilization can account for the high propensity of ALS-linked variants to aggregate and also provides rationale for their reported functional defects ...


Single-Molecule Studies Of Replication Kinetics In Response To Dna Damage, Divya Ramalingam Iyer May 2017

Single-Molecule Studies Of Replication Kinetics In Response To Dna Damage, Divya Ramalingam Iyer

GSBS Dissertations and Theses

In response to DNA damage during S phase, cells slow DNA replication. This slowing is orchestrated by the intra-S checkpoint and involves inhibition of origin firing and reduction of replication fork speed. Slowing of replication allows for tolerance of DNA damage and suppresses genomic instability. Although the mechanisms of origin inhibition by the intra-S checkpoint are understood, major questions remain about how the checkpoint regulates replication forks: Does the checkpoint regulate the rate of fork progression? Does the checkpoint affect all forks, or only those encountering damage? Does the checkpoint facilitate the replication of polymerase-blocking lesions? To address these questions ...


Novel Mechanisms Regulating Dopamine Transporter Endocytic Trafficking: Ack1-Controlled Endocytosis And Retromer-Mediated Recycling, Sijia Wu Jan 2017

Novel Mechanisms Regulating Dopamine Transporter Endocytic Trafficking: Ack1-Controlled Endocytosis And Retromer-Mediated Recycling, Sijia Wu

GSBS Dissertations and Theses

Dopamine transporters (DAT) facilitate high-affinity presynaptic dopamine (DA) reuptake in the central nervous system, and are required to constrain extracellular DA levels and maintain presynaptic DAergic tone. DAT is the primary target for addictive and therapeutic psychostimulants, which require DAT binding to elicit reward. DAT availability at presynaptic terminals ensures its proper function, and is dynamically regulated by endocytic trafficking. My thesis research focused on two fundamental questions: 1) what are the molecular mechanisms that control DAT endocytosis? and 2) what are the mechanism(s) that govern DAT’s post-endocytic fate? Using pharmacological and genetic approaches, I discovered that a ...


Role Of Energy Metabolism In The Thermogenic Gene Program, Minwoo Nam Jan 2017

Role Of Energy Metabolism In The Thermogenic Gene Program, Minwoo Nam

GSBS Dissertations and Theses

In murine and human brown adipose tissue (BAT), mitochondria are powerful generators of heat. Emerging evidence has suggested that the actions of mitochondria extend beyond this conventional biochemical role. In mouse BAT and cultured brown adipocytes, impaired mitochondrial respiratory capacity is accompanied by attenuated expression of Ucp1, a key thermogenic gene, implying a mitochondrial retrograde signaling. However, few have investigated this association in the context of mitochondria-nucleus communication.

Using mice with adipose-specific ablation of LRPPRC, a regulator of respiratory capacity, we show that respiration-dependent retrograde signaling from mitochondria to nucleus contributes to transcriptional and metabolic reprogramming of BAT. Impaired respiratory ...


The Role Of Mdm2 Phosphorylation In P53 Responses To Dna Damage And Tumor Suppression: A Dissertation, Michael I. Carr Jul 2016

The Role Of Mdm2 Phosphorylation In P53 Responses To Dna Damage And Tumor Suppression: A Dissertation, Michael I. Carr

GSBS Dissertations and Theses

The p53 tumor suppressor protein is upregulated in response to DNA damage and other stress signals. The upregulation of p53 involves freeing it from negative regulation imposed by Mdm2 and MdmX (Mdm4). Accumulating evidence indicates that phosphorylation of Mdm proteins by different stress-activated kinases such as ATM or c-Abl significantly impacts p53 functions. We have previously shown that ATM phosphorylation of Mdm2 Ser394 is required for robust p53 stabilization and activation following DNA damage.

This dissertation describes in vivo examination of the mechanism by which Mdm2 Ser394 phosphorylation impacts p53 activities and its contribution to suppression of oncogene and DNA ...


Investigating The Architecture And Vesicle Tethering Function Of The Yeast Exocyst Complex: A Dissertation, Margaret R. Heider Jan 2016

Investigating The Architecture And Vesicle Tethering Function Of The Yeast Exocyst Complex: A Dissertation, Margaret R. Heider

GSBS Dissertations and Theses

The exocyst is an evolutionarily conserved, hetero-octameric protein complex proposed to serve as a multi-subunit tethering complex for exocytosis, although it remains poorly understood at the molecular level. The classification of the exocyst as a multisubunit tethering complex (MTC) stems from its known interacting partners, polarized localization at the plasma membrane, and structural homology to other putative MTCs. The presence of 8 subunits begs the questions: why are so many subunits required for vesicle tethering and what are the contributions of each of these subunits to the overall structure of the complex? Additionally, are subunit or subcomplex dynamics a required ...


Systematic Dissection Of Roles For Chromatin Regulators In Dynamics Of Transcriptional Response To Stress In Yeast: A Dissertation, Hsiuyi V. Chen Dec 2015

Systematic Dissection Of Roles For Chromatin Regulators In Dynamics Of Transcriptional Response To Stress In Yeast: A Dissertation, Hsiuyi V. Chen

GSBS Dissertations and Theses

The following work demonstrates that chromatin regulators play far more pronounced roles in dynamic gene expression than they do in steady-state. Histone modifications have been associated with transcription activity. However, previous analyses of gene expression in mutants affecting histone modifications show limited alteration. I systematically dissected the effects of 83 histone mutants and 119 gene deletion mutants on gene induction/repression in response to diamide stress in yeast. Importantly, I observed far more changes in gene induction/repression than changes in steady-state gene expression. The extensive dynamic gene expression profile of histone mutants and gene deletion mutants also allowed me ...


Roles Of Protein Arginine Methyltransferase 7 And Jumonji Domain-Containing Protein 6 In Adipocyte Differentiation: A Dissertation, Yu-Jie Hu Oct 2015

Roles Of Protein Arginine Methyltransferase 7 And Jumonji Domain-Containing Protein 6 In Adipocyte Differentiation: A Dissertation, Yu-Jie Hu

GSBS Dissertations and Theses

Regulation of gene expression comprises a wide range of mechanisms that control the abundance of gene products in response to environmental and developmental changes. These biological processes can be modulated by posttranslational modifications including arginine methylation. Among the enzymes that catalyze the methylation, protein arginine methyltransferase 7 (PRMT7) is known to modify histones to repress gene expression. Jumonji domain-containing protein 6 (JMJD6) is a putative arginine demethylase that potentially antagonize PRMT7. However, the biological significance of these enzymes is not well understood. This thesis summarizes the investigation of both PRMT7 and JMJD6 in cell culture models for adipocyte differentiation. The ...


Optimizing Rna Library Preparation To Redefine The Translational Status Of 80s Monosomes: A Dissertation, Erin E. Heyer Oct 2015

Optimizing Rna Library Preparation To Redefine The Translational Status Of 80s Monosomes: A Dissertation, Erin E. Heyer

GSBS Dissertations and Theses

Deep sequencing of strand-specific cDNA libraries is now a ubiquitous tool for identifying and quantifying RNAs in diverse sample types. The accuracy of conclusions drawn from these analyses depends on precise and quantitative conversion of the RNA sample into a DNA library suitable for sequencing. Here, we describe an optimized method of preparing strand-specific RNA deep sequencing libraries from small RNAs and variably sized RNA fragments obtained from ribonucleoprotein particle footprinting experiments or fragmentation of long RNAs. Because all enzymatic reactions were optimized and driven to apparent completion, sequence diversity and species abundance in the input sample are well preserved ...


Investigating The Effects Of Mutant Fus On Stress Response In Amyotrophic Lateral Sclerosis: A Thesis, Laura J. Kaushansky Aug 2015

Investigating The Effects Of Mutant Fus On Stress Response In Amyotrophic Lateral Sclerosis: A Thesis, Laura J. Kaushansky

GSBS Dissertations and Theses

During stress, eukaryotes regulate protein synthesis in part through formation of cytoplasmic, non-membrane-bound complexes called stress granules (SGs). SGs transiently store signaling proteins and stalled translational complexes in response to stress stimuli (e.g. oxidative insult, DNA damage, temperature shifts and ER dysfunction). The functional outcome of SGs is proper translational regulation and signaling, allowing cells to overcome stress.

The fatal motor neuron disease Amyotrophic Lateral Sclerosis (ALS) develops in an age-related manner and is marked by progressive neuronal death, with cytoplasmic protein aggregation, excitotoxicity and increased oxidative stress as major hallmarks. Fused in Sarcoma/Translocated in Liposarcoma (FUS) is ...


Regulation Of Cdk1 Activity During The G1/S Transition In S. Cerevisiae Through Specific Cyclin-Substrate Docking: A Dissertation, Samyabrata Bhaduri Oct 2014

Regulation Of Cdk1 Activity During The G1/S Transition In S. Cerevisiae Through Specific Cyclin-Substrate Docking: A Dissertation, Samyabrata Bhaduri

GSBS Dissertations and Theses

Several cell cycle events require specific forms of the cyclin-CDK complexes. It has been known for some time that cyclins not only contribute by activating the CDK but also by choosing substrates and/or specifying the location of the CDK holoenzyme. There are several examples of B-type cyclins identifying certain peptide motifs in their specific substrates through a conserved region in their structure. Such interactions were not known for the G1 class of cyclins, which are instrumental in helping the cell decide whether or not to commit to a new cell cycle, a function that is non-redundant with B-type cylins ...


Small Rnas And Argonautes Provide A Paternal Epigenetic Memory Of Germline Gene Expression To Promote Thermotolerant Male Fertility: A Dissertation, Colin C. Conine Sep 2014

Small Rnas And Argonautes Provide A Paternal Epigenetic Memory Of Germline Gene Expression To Promote Thermotolerant Male Fertility: A Dissertation, Colin C. Conine

GSBS Dissertations and Theses

During each life cycle, gametes must preserve and pass on both genetic and epigenetic information, making the germline both immortal and totipotent. In the male germline the dramatic morphological transformation of a germ cell through meiosis, into a sperm competent for fertilization, while retaining this information is an incredible example of cellular differentiation. This process of spermatogenesis is inherently thermosensitive in numerous metazoa ranging from worms to man. Here, I describe the role of two redundant AGO-class paralogs, ALG-3/4, and their small RNA cofactors, in promoting thermotolerant male fertility in Caenorhabditis elegans. alg-3/4 double mutants exhibit temperature dependent ...


Molecular Landscape Of Induced Reprogramming: A Dissertation, Chao-Shun Yang Feb 2014

Molecular Landscape Of Induced Reprogramming: A Dissertation, Chao-Shun Yang

GSBS Dissertations and Theses

Recent breakthroughs in creating induced pluripotent stem cells (iPS cells) provide alternative means to obtain embryonic stem (ES) cell-like cells without destroying embryos by introducing four reprogramming factors (Oct3/4, Sox2, and Klf4/c-Myc or Nanog/Lin28) into somatic cells. However, the molecular basis of reprogramming is largely unknown. To address this question, we employed microRNAs, small molecules, and conducted genome-wide RNAi screen, to investigate the regulatory mechanisms of reprogramming.

First we showed that depleting miR-21 and miR-29a enhances reprogramming in mouse embryonic fibroblasts (MEFs). We also showed that p53 and ERK1/2 pathways are regulated by miR-21 and miR-29a ...


Investigation Of Multiple Concerted Mechanisms Underlying Stimulus-Induced G1 Arrest In Yeast: A Dissertation, Patricia A. Pope Jun 2013

Investigation Of Multiple Concerted Mechanisms Underlying Stimulus-Induced G1 Arrest In Yeast: A Dissertation, Patricia A. Pope

GSBS Dissertations and Theses

Progression through the cell cycle is tightly controlled, and the decision whether or not to enter a new cell cycle can be influenced by both internal and external cues. For budding yeast one such external cue is pheromone treatment, which can induce G1 arrest. Two distinct mechanisms are known to be involved in this arrest, one dependent on the arrest protein Far1 and one independent of Far1, but the exact mechanisms have remained enigmatic. The studies presented here further elucidate both of these mechanisms.

We looked at two distinct aspects of the Far1-independent arrest mechanism. First, we studied the role ...


Role Of Map4k4 In Skeletal Muscle Differentiation: A Dissertation, Mengxi Wang May 2013

Role Of Map4k4 In Skeletal Muscle Differentiation: A Dissertation, Mengxi Wang

GSBS Dissertations and Theses

Skeletal muscle is a complicated and heterogeneous striated muscle tissue that serves critical mechanical and metabolic functions in the organism. The process of generating skeletal muscle, myogenesis, is elaborately coordinated by members of the protein kinase family, which transmit diverse signals initiated by extracellular stimuli to myogenic transcriptional hierarchy in muscle cells. Mitogen-activated protein kinases (MAPKs) including p38 MAPK, c-Jun N terminal kinase (JNK) and extracellular signal-regulated protein kinase (ERK) are components of serine/threonine protein kinase cascades that play important roles in skeletal muscle differentiation. The exploration of MAPK upstream kinases identified mitogen activated protein kinase kinase kinase kinase ...


Transcriptional Regulation Of A Human H4 Histone Gene Is Mediated By Multiple Elements Interacting With Similar Transcription Factors: A Dissertation, Thomas J. Last May 1998

Transcriptional Regulation Of A Human H4 Histone Gene Is Mediated By Multiple Elements Interacting With Similar Transcription Factors: A Dissertation, Thomas J. Last

GSBS Dissertations and Theses

Synthesis of histone proteins occurs largely during the S phase of the cell cycle and coincides with DNA replication to provide adequate amounts of histones necessary to properly package newly replicated DNA. Controlling transcription from cell cycle dependent and proliferation specific genes, including histone H4, is an important level of regulation in the overall governance of the cell growth process. Coordination of histone gene transcription results from the cumulative effects of cell signaling pathways, dynamic chromatin structure and multiple transcription factor interactions. The research of this dissertation focused on the characterization and identification of transcription factors interacting on the human ...


Molecular Characterization Of Mitofilin, A Novel, Mitochondrial, Coiled Coil Protein, And The Relationship Between Organism Complexity And Coiled Coil Protein-Mediated Structure: A Dissertation, Paul R. Odgren Nov 1995

Molecular Characterization Of Mitofilin, A Novel, Mitochondrial, Coiled Coil Protein, And The Relationship Between Organism Complexity And Coiled Coil Protein-Mediated Structure: A Dissertation, Paul R. Odgren

GSBS Dissertations and Theses

In the course of experiments designed to identify and characterize structural proteins of the nuclear matrix, one antibody was generated which recognized an extraction-resistant cytoplasmic protein. This antibody was used as the starting point in the cloning and molecular characterization of a novel protein of the inter-membrane space of the mitochondrion which has been named mitofilin. Mitofilin is expressed in all human cell types, and murine homologues also exist. Mitofilin associates only with mitochondria and not with other membrane-bounded organelles such as Golgi or endoplasmic reticulum. This observation has been confirmed both by biochemical fractionation and multi-label fluorescence microscopy. Recombinant ...