Biochemistry, Biophysics, and Structural Biology Commons^™

Mechanisms And Roles Of Dynamic Actin Assembly Around Dysfunctional Mitochondria, Tak Shun Fung

Dartmouth College Ph.D Dissertations

Possessing the ability to efficiently generate ATP required to sustain cellular functions, mitochondria are often considered the ‘powerhouses of the cell’. However, our understanding of mitochondria in cell biology was further expanded when we recognized that communication between this unique organelle and the rest of the cell regulates cellular bioenergetics, metabolism and signaling processes such as mitophagy and apoptosis. Here, I investigate signaling between mitochondria and the actin cytoskeleton, and how this signaling regulates mitochondrial dynamics and cellular function. Specifically, I find that, upon mitochondrial dysfunction, actin polymerizes rapidly around the dysfunctional organelle, which we term ‘acute damage-induced actin’ (ADA). …

Editorial: Mitochondria, Metabolism And Cardiovascular Diseases, Jun-Ichiro Koga, Xinghui Sun, Masuko Ushio-Fukai

Department of Biochemistry: Faculty Publications

No abstract provided.

Studying Acetylation Of Aconitase Isozymes By Genetic Code Expansion, Jessica Araujo

Graduate Theses and Dissertations

The tricarboxylic acid (TCA) cycle is a very important, centrally located, energy-producing pathway that connects numerous other metabolic and regulatory pathways. Enzymes of this cycle have been more recently implicated in various cancers and neurometabolic disorders, however, the exact mechanism by which this happens becomes quite complex when considering the potential modification of these enzymes and the presence of multiple forms of the enzymes and therefore there is much to be studied in this area.

Aconitase has become a recent enzyme of interest as its substrate, citrate, has been found to play a major role in many vital processes within …

Role Of Bmi1 In Acute Lung Injury, María Helena Hernández-Cuervo

USF Tampa Graduate Theses and Dissertations

Acute Lung Injury (ALI) is a set of signs and symptoms that lead to acute hypoxemic respiratory failure characterized by bilateral pulmonary infiltrates not attributed to cardiogenic origin. It is caused by a massive innate immune response, with the migration of white blood cells (neutrophils and macrophages principally) and a cytokine storm, followed by alterations in mitochondrial function, increase in reactive oxygen species production, and oxidative stress that in turn induces more mitochondrial damage. Several studies have shown that mitochondrial alterations are key events in the mechanism of ALI and reducing mitochondrial dysfunction could be a possible target in the …

Determining The Effects Of Chemical Exposure On Hepatocyte Mitochondrial Networks And Cell Viability, Bethany Eaton

All Master's Theses

Mitochondria are cellular organelles that are becoming more recently studied. One of their main functions is the production of energy through cellular respiration, which is crucial to cell life. However, they are also associated with numerous disease states. It is hypothesized that reactive oxygen species (ROS), largely produced in mitochondria, induce oxidative stress and affect mitochondrial morphology along with cell viability. This study compares chemical exposure of menadione, an ROS producer, and phthalates (plasticizers) on two mouse hepatocyte cell lines to determine the effects they have on mitochondrial morphology and cell viability. Three experiments were performed to analyze the effects …

Mitochondrial Metal Homeostasis: A Look Into Iron And Copper Mobilization Within Mitochondria, Jonathan Dietz

Department of Biochemistry: Dissertations, Theses, and Student Research

Cellular iron and copper homeostasis is interdependent with mitochondrial iron and copper homeostasis. Mitochondria must import iron to form iron-sulfur clusters and heme, while it must import copper for usage and storage. These cofactors are incorporated into mitochondrial proteins that support essential functions, including cellular respiration and maintaining redox homeostasis. In turn, mitochondria also provide heme to the cell and enables the biogenesis of cytosolic iron-sulfur cluster containing proteins, while also providing copper when needed. Due to both metals (and their modified species) reactivity, iron and copper are stored and trafficked within the mitochondria carefully. Although these cofactors are crucial …

Mitochondrial Contact Site And Cristae Organizing System (Micos) Machinery Supports Heme Biosynthesis By Enabling Optimal Performance Of Ferrochelatase, Jonathan V. Dietz, Mathilda M. Willoughby, Robert B. Piel, Teresa A. Ross, Iryna Bohovych, Hannah G. Addis, Jennifer L. Fox, William N. Lanzilotta, Harry A. Dailey, James A. Wohlschlegel, Amit R. Reddi, Amy E. Medlock, Oleh Khalimonchuk

Department of Biochemistry: Faculty Publications

Heme is an essential cofactor required for a plethora of cellular processes in eukaryotes. In metazoans the heme biosynthetic pathway is typically partitioned between the cytosol and mitochondria, with the first and final steps taking place in the mitochondrion. The pathway has been extensively studied and its biosynthetic enzymes structurally characterized to varying extents. Nevertheless, understanding of the regulation of heme synthesis and factors that influence this process in metazoans remains incomplete. Therefore, we investigated the molecular organization as well as the physical and genetic interactions of the terminal pathway enzyme, ferrochelatase (Hem15), in the yeast Saccharomyces cerevisiae. Biochemical and …

Late Embryogenesis Abundant Proteins And Mitochondrial Membranes From An Animal Extremophile: Insights Into Severe Water Stress, John Marcus Anderson

LSU Doctoral Dissertations

This dissertation focuses on two major topics germane to mechanisms by which animals tolerate extreme water stress. First, the impact of transgenic expression of late embryogenesis abundant proteins (LEA) on water stress tolerance of the fruit fly Drosophila melanogaster was investigated. The overall aim was to extend current understanding of the protective properties of LEA proteins documented with isolated cells to a desiccation-sensitive organism during exposure to drying and hyperosmotic stress. Four lines of D. melanogaster were created that expressed transgenes encoding selected LEA proteins originally identified in embryos of the extremophile Artemia franciscana. After 80% tissue water loss, …

Evaluating Bioenergetics And Mitochondrial Dynamics In Patient Fibroblasts With Pathogenic Mitochondrial Dna Mutations Causing Leigh Syndrome, Ajibola Bakare

Graduate Theses and Dissertations

Leigh syndrome (LS) is a rare fatal mitochondrial disorder of infants caused by pathogenic mutations in the nuclear (nDNA) or mitochondrial DNA (mtDNA) leading to mitochondrial dysfunction. The extent to which pathogenic mtDNA variants regulate disease severity in LS is not well understood. The heterogeneous nature of this disorder, based in part by complex mitochondrial genetics, and the nuclear and mitochondrial cross-talk has made it particularly challenging to investigate and develop therapies for treating LS . While the prognosis is poor, several studies are underway to understand the pathophysiology of LS. This dissertation provides a comprehensive structural and functional analysis …

A Time-Course Characterization Of Muscle Function And Mitochondrial Markers During Colorectal Cancer-Induced Cachexia In Tumor-Bearing Male Mice, Ana Cabrera Ayuso

Graduate Theses and Dissertations

Cachexia is a multisystemic and multifactorial syndrome prevalent in cancer patients. It is clinically defined by involuntary loss of >5% weight in a six-month window, despite nutritional interventions. A negative energy balance characterizes cancer cachexia (CC), it is associated with weakness and fatigue in skeletal muscle. Impaired muscle function is associated with lower quality of life in cancer patients. Defects in mitochondrial function are strongly associated with muscle wasting. This study explored muscular contractile function and mitochondrial quality control (MQC) markers in soleus, gastrocnemius, and tibialis anterior (TA) muscles of C26-induced male tumor-bearing mice during a 25-day time course. It …

Mitochondrial Distribution Of Glycine Receptors In Motor Neuron Cell Lines, Katsiaryna Milashevich

Student Theses and Dissertations

Although non-essential, glycine plays an important role in major metabolic reactions and is most known for its anti-inflammatory effects. An accumulation of contemporary research has shown that glycine is able to stabilize membrane potential using glycine receptors at the cellular level and to protect mitochondrial function directly, whether it is from inflammation, heavy metal poisoning, or ischemia-induced neuroinflammation. In this research, the existence of a hypothetical mitochondrial glycine receptor is examined. Immunofluorescence imaging was used to examine the presence of the glycine receptor subunits alpha 1 and alpha 2 in both non- differentiated and differentiated neuroblastoma cell lines. The preliminary …

Using Crispr-Cas9 To Construct Knockout Mutants In Dna-Repair Genes In Arabidopsis Thaliana, David Campbell

Honors Program: Senior Projects (Public)

The mitochondria are known as the powerhouse of the cell, and just like a real powerhouse, it can be a dangerous place to store sensitive information. Energy generation and redox reactions in the mitochondria can cause damage to the DNA stored there, resulting in a higher mutation rate. Compared to their animal counterparts, however, plant mitochondria exhibit a lower mutation rate and a higher recombination rate. It is hypothesized that the unique DNA repair methods present in plant mitochondria are responsible for the phenomena observed there. To study the mechanics of DNA-repair in this organelle, however, researchers must be able …

Mnrr1: Understanding The Role Of A Novel Mitochondrial-Nuclear Regulator, Stephanie L. Gladyck

Wayne State University Dissertations

Mitochondria are complex organelles that generate most of the energy required to sustain life and function in metabolic and signaling pathways required to maintain cellular homeostasis. MNRR1 (mitochondrial nuclear retrograde regulator 1 or CHCHD2) is a small, bi-organellar twin CX9C protein that is emerging as an important regulator of mitochondrial function, apoptosis, and cellular stress by participating in mitochondrial-nuclear crosstalk. Our lab has previously shown that in the mitochondria, MNRR1 regulates complex IV (Cytochrome c oxidase or COX) and is able to finetune the oxidase function through phosphorylation status. We have also shown that during stress, mitochondrial MNRR1 levels deplete, …

Huntingtin Aggregation At Interfaces Associated With Membranes And Organelles, Adewale Vincent Adegbuyiro

Graduate Theses, Dissertations, and Problem Reports (ETD)

Huntington’s Disease (HD) is a genetic neurodegenerative disease caused by the expansion of polyglutamine (polyQ) domain within the first exon (exon1) of the huntingtin (htt) protein. Due to this mutation within the polyQ domain, htt aggregates into various toxic species such as oligomers, fibrils, and other amorphous aggregates. While the aggregation of htt strongly correlates with polyQ length, other factors, e.g. interaction with membranes or organelles and posttranslational modifications (PTMs), modulate aggregation. The first 17 N-terminal amino acids (Nt17) that precede the polyQ in htt-exon1 enhances aggregation and facilitated binding of htt to membranous organelles, promoting morphological changes and disfunction. …

Mechanistic Insights Of Mitochondrial Reactive Oxygen Species In Alzheimer's Disease Models, Jakob C. Green

Theses and Dissertations

Alzheimer’s disease (AD) is a neurodegenerative disease that results in impaired cognition, disorientation, confusion, poor judgement, and behavioral changes. The mitochondrial cascade hypothesis (MCH), which postulates that accumulating oxidative stress and mitochondrial dysfunction plays an integral role in the development of the disease, potentially upstream, in conjunction with or independent of Aβ and tau. The literature supports the critical role of mitochondrial dysfunction in the progression and development of AD, but is inconclusive about what precise role, as initiator or delegate, it performs. Regardless, the impact that oxidative stress and mitochondrial dysfunction have on AD deserves further study and investigation. …

Function Of Mllt3 In Liver Metabolism, Grace Ann Hammack

Master's Theses

The chromatin regulator MLLT3 recognizes target genes through the YEATS domain that identifies post-translationally modified histones, with preference for crotonyl and acetyl marks, and recruits different multiprotein effector complexes through its C-terminal domain to target genes. To study the role of MLLT3 in gene regulation, the Zeleznik-Le and Hemenway labs developed Mllt3 whole-body knockout (Mllt3;Rosa26-CreERT2) mice. These mice have a hematopoietic stem cell phenotype and an unexpected obesity and hepatic steatosis phenotype. It was unknown whether these phenotypes were from liver intrinsic effects or influenced by other parts of the body. To study this fatty liver phenotype further, Mllt3;Alb-Cre were …

Calcineurin, Trevor P. Creamer

Molecular and Cellular Biochemistry Faculty Publications

The serine/threonine phosphatase calcineurin acts as a crucial connection between calcium signaling the phosphorylation states of numerous important substrates. These substrates include, but are not limited to, transcription factors, receptors and channels, proteins associated with mitochondria, and proteins associated with microtubules. Calcineurin is activated by increases in intracellular calcium concentrations, a process that requires the calcium sensing protein calmodulin binding to an intrinsically disordered regulatory domain in the phosphatase. Despite having been studied for around four decades, the activation of calcineurin is not fully understood. This review largely focuses on what is known about the activation process and highlights aspects …

Protease Oma1 Modulates Mitochondrial Bioenergetics And Ultrastructure Through Dynamic Association With Micos Complex, Martonio P. Viana

Department of Biochemistry: Dissertations, Theses, and Student Research

Remodeling of mitochondrial ultrastructure is a complex dynamic process that is critical for a variety of mitochondrial functions and apoptosis. Although the key regulators of this process - mitochondrial contact site and cristae junction organizing system (MICOS) and GTPase Optic Atrophy 1 (OPA1) have been characterized, the mechanisms behind this regulation remain incompletely defined. Here, we found that in addition to its role in mitochondrial division, metallopeptidase OMA1 is required for maintenance of contacts between the inner and outer membranes through a dynamic association with MICOS. This association is independent of OPA1, appears to be mediated via the MIC60 MICOS …

The Shape Of Metabolism: Mitochondrial Dynamics, Remodeling, And Bioenergetic Reprogramming In Disease, Carl Decker

KGI Theses and Dissertations

Mitochondria are dynamic, double-membrane bound hubs of bioenergetics, cell signaling, and redox balance that exist as an oscillating network of fused superstructures and smaller, single organelles. Importantly, their position at the junction of catabolic and anabolic metabolism connects these morphological fluctuations to larger cellular metabolic programs, which in turn have implicated mitochondrial dynamics in a number of disease states and a varied set of cell phenomena. For example, differentiation of memory t-cells is dependent on mitochondrial network morphology, and in particular on remodeling dynamics that yield fused mitochondrial assemblies favoring oxidative phosphorylation-driven metabolism. In contrast, many cancers have been shown …

Quantification Of Mitochondrial Zinc Homeostasis And Analysis Of Zinc And Polyamine-Mediated Axonal Trafficking, Dylan Hunt Fudge

Electronic Theses and Dissertations

The zinc ion is an important emerging signaling molecule for biological processes. In this work we engineered improved zinc sensors based on our previously developed fluorescent sensor GZnP1 to provide sensors with a higher fluorescent readout, faster kinetics, and a superior sensitivity to zinc. We utilized these zinc sensors and further developed the sensors to answer questions pertaining to biological zinc. We showed the labile zinc concentration in the mitochondrial matrix was less than 1 pM while the labile zinc concentration in the cytosol and mitochondrial IMS were comparable (~100 pM) across four different cell lines. Using these zinc sensors …

Acetoacetate Enhances Oxidative Metabolism And Response To Toxicants Of Cultured Renal Cells, Trudi Maria Denoon

Theses and Dissertations

In vitro methods can be cost effective and facilitate large scale drug screening in the pharmaceutical industry. Renal proximal tubular cells have been a prime target for drug induced toxicity. LLC-PK1 cells possess many transport functions of the proximal tubule epithelia, however, its energy metabolism differs from the highly oxidative tubule metabolism in vivo. This may impact its reliability in predicting toxicity. Modulating the growth media composition has been shown to shift cultured liver and muscle cells from high glycolytic activity to increased oxidative metabolism, but few studies have been done on renal cells. This study is designed to test …

Characterization Of The Biochemical Properties Of Nudt8, A Novel Coa-Degrading Enzyme That Localizes To The Mitochondria, Evan W. Kerr

Graduate Theses, Dissertations, and Problem Reports (ETD)

Coenzyme A (CoA) is a vital cofactor that is required for a variety of metabolic reactions including the TCA cycle and the synthesis and oxidation of fatty acids, amino acids and ketone bodies. The importance of CoA is underscored by its tight regulation, as prolonged elevations or inability to synthesize adequate amounts of this cofactor lead to severe metabolic dysfunction. Regulation of CoA biosynthesis has been extensively characterized, however less is known about regulation of CoA and its thioesters via degradation. Presently, two CoA-degrading enzymes, Nudt7 and Nudt19 have been identified as regulators of the peroxisomal pool of (acyl-)CoA in …

Novel Insights Into The Critical Role Of Cardiolipin In Cellular Metabolism And Mitochondrial Physiology, Jiajia Ji

Wayne State University Dissertations

Cardiolipin (CL) is the signature phospholipid of mitochondria. CL and its remodeling exert critical roles in biological processes both inside and outside of mitochondria. CL abnormalities have been associated with various mitochondrial disorders and aging. Understanding the role of CL in mitochondrial physiology and cellular metabolism could provide valuable insights into cell biology and human health. Several metabolic alterations have been reported in CL-deficient cells, including accumulated lactate, decreased PDH activity, and decreased TCA cycle function. This dissertation connected these findings by showing abnormal NAD+ metabolism in various models lacking CL. Importantly, it shows that NAD+ supplementation improves mitochondrial function …

From Synthesis To Utilization: The Ins And Outs Of Mitochondrial Heme, Samantha A. Swenson, Courtney M. Moore, Jason R. Marcero, Amy E. Medlock, Amit R. Reddi, Oleh Khalimonchuk

Department of Biochemistry: Faculty Publications

Heme is a ubiquitous and essential iron containing metallo-organic cofactor required for virtually all aerobic life. Heme synthesis is initiated and completed in mitochondria, followed by certain covalent modifications and/or its delivery to apo-hemoproteins residing throughout the cell. While the biochemical aspects of heme biosynthetic reactions are well understood, the trafficking of newly synthesized heme—a highly reactive and inherently toxic compound—and its subsequent delivery to target proteins remain far from clear. In this review, we summarize current knowledge about heme biosynthesis and trafficking within and outside of the mitochondria.

A Bioinformatic Approach To Exploring Land Plant Evolution, Lauren Margaret Orton

Graduate Research Theses & Dissertations

Today, researchers are inundated with an overwhelming amount of data due to advances in DNA sequencing technologies. This has benefited the fields of both bioinformatics and phylogenomics substantially. With the ability to increase sampling at both the taxonomic and molecular levels, we are now able to produce robust phylogenomic reconstructions and better discern relationships between taxa.

The goals of this dissertation are in two distinct parts: 1) to advance the understanding of land plant terrestrialization and evolution through examination of the closest relative to the land plant lineage, a species of green algae; and 2) to explore evolution among a …

Seasonal Variation In Mitochondrial Bioenergetics Of The Bluegill Sunfish, Lepomis Macrochirus, From A Shallow Midwest River, Derick Isaac Lamptey

Masters Theses

As average global temperature increase, the frequency and magnitude of extreme temperatures in shallow aquatic ecosystems are more ubiquitous. In order to understand how these changing thermal regimes affect aquatic ectotherms, it is essential to develop studies evaluating the response of ectotherms to seasonal fluctuating thermal regimes. Previous studies on fluctuating temperature regimes have reported an increased physiological stress leading to morphological, behavioral and biochemical adaptations. From the latter, the adaptive capacity and seasonal performance associated with optimal function of the oxidative phosphorylation system (OXPHOS) are key for species persistence. However, studies on this matter are scarce. This study explores …

Mitochondrial Metabolism In Astrocytes Regulates Brain Bioenergetics, Neurotransmission And Redox Balance, Jordan Rose, Christian Brian, Aglaia Pappa, Mihalis I. Panayiotidi, Rodrigo Franco

School of Veterinary and Biomedical Sciences: Faculty Publications

In the brain, mitochondrial metabolism has been largely associated with energy production, and its dysfunction is linked to neuronal cell loss. However, the functional role of mitochondria in glial cells has been poorly studied. Recent reports have demonstrated unequivocally that astrocytes do not require mitochondria to meet their bioenergetics demands. Then, the question remaining is, what is the functional role of mitochondria in astrocytes? In this work, we review current evidence demonstrating that mitochondrial central carbon metabolism in astrocytes regulates overall brain bioenergetics, neurotransmitter homeostasis and redox balance. Emphasis is placed in detailing carbon source utilization (glucose and fatty acids), …

Xenobiotic Exposure Requires Mitochondrial Metabolism For Redox Homeostasis And Survival In Astrocytes, Jordan Rose

Department of Biochemistry: Dissertations, Theses, and Student Research

Astrocytes are integral components of glutamatergic neurotransmission, providing essential metabolic processes for neuronal homeostasis and acting as the first line of defense against xenobiotics crossing the blood brain barrier. Arsenic is a xenobiotic with widespread natural and industrial prevalence, and has been linked to impaired neurodevelopment and neuronal death. Given the integrated metabolic nature of astrocytes and neurons, we sought to explore how arsenic impacts astrocyte metabolism in order to better understand the mechanisms of xenobiotic toxicity in the mammalian brain.

We demonstrate that astrocyte viability depends upon de novoglutathione (GSH) synthesis during arsenic exposure, and sub-lethal arsenic exposure …

A Dedicated Chaperone Mediates The Safe Transfer Of Mitoribosomal Proteins To Their Site Of Assembly, Gabrielle Ashley Hillman

Graduate School of Biomedical Sciences Theses and Dissertations

Mitochondrial ribosomes are functionally specialized for the synthesis of several essential inner membrane proteins of the respiratory chain. While remarkable progress has recently been made towards understanding the structure of mitoribosomes, the unique pathways and factors that facilitate their biogenesis remain largely unknown. This dissertation defines the physiological role of an evolutionarily conserved yeast protein called Mam33 in mitochondrial ribosome assembly. The biomedical relevance of this finding stems from the fact that mutations or changes in its expression of the human ortholog p32 result in mitochondrial dysfunction. In human patients, bi-allelic mutations cause severe multisystemic defects in mitochondrial energy metabolism, …

Hormone Signaling, Gene Expression, And Mitochondrial Hormone Receptor Expression In Avian Muscle (Cells), Kentu Rushadd Lassiter

Graduate Theses and Dissertations

Mitochondria are vital to the proper growth and function of muscle cells since they’re responsible for the majority of ATP production used for cellular energy. Previous studies have investigated how differences in mitochondrial function affects feed efficiency (FE) in broilers phenotyped for High and Low FE. Low FE broilers have been shown to have increased levels of reactive oxygen species (ROS), thus contributing to higher levels of oxidative stress and damage seen in these birds. Global gene and protein expression studies conducted on breast muscle of the High FE and Low FE phenotypes have suggested that differences in mitochondrial function …