Cell Biology Commons^™

Effects Of Osmotic Stress On Oxygen Consumption Of Drosophila Cells (Kc167), Ali A. Ahmed, Rajib Hassan, Michael A. Menze

The Cardinal Edge

This article investigates the effect of osmotic stress on a drosophila cell line called Kc167.

The embryonic-derived fly (Drosophila melanogaster) cell line, Kc-167, was employed as a model for water-stress sensitivity in Arthropods. Like mammalian cells, cells derived from the fruit fly contain the same basic set of membranous components found in all eukaryotic cells. A series of experiments were conducted to characterize the mitochondrial repones of Kc167 cells to water stress. Precisely, the oxygen flux in a sealed respirometer chamber containing Kc167 cells was measured under hyperosmotic and control conditions. Mitochondrial uncouplers were used in some experiments for intact …

Does Vdac2 Have A Bh3 Domain?, Lillian Ferkany

Honors Theses

Mitochondrial outer membrane permeabilization (MOMP) by Bax oligomerization triggers apoptosis. BCl-2 family proteins, classified as BH3 only proteins, pro-survival proteins, or pro-apoptotic proteins, control apoptosis partly through their agonist or antagonistic effects on Bax, which are mediated by their conserved BH3 domains. All BH3 domains form an alpha helix containing 5-7 conserved hydrophobic residues, designated H0-H5, and one conserved aspartic acid that drive interaction with Bax and other ‘multi-domain’ BCl-2 members. BH3 agonists induce Bax oligomerization, while BH3 antagonists sequester Bax to prevent MOMP. We discovered that voltage dependent anion channels (VDACs) in the MOM contain a putative BH3-like domain …

Mitochondrial Roles In Developmentally Programmed Heart Disease, Eli John Louwagie

Dissertations and Theses

Offspring of diabetic and obese mothers (ODOM) have greater risks of heart disease at birth and later in life. However, prevention is hindered because underlying mechanisms are poorly understood. Mounting studies in the Developmental Origins of Health and Disease field suggest that mitochondria play key roles in developmentally programmed heart disease similar to the roles they play in cardiomyopathy in adults with diabetes and obesity. However, whether mitochondria are responsible for the short[1]and long-term cardiac disease seen in ODOM remains unknown. Here, we sought to delineate the roles of mitochondria in the hearts of ODOM, determine whether mitochondria are playing …

Therapies For Mitochondrial Disorders, Kayli Sousa Smyth, Anne Mulvihill

SURE Journal: Science Undergraduate Research Experience Journal

Mitochondria are cytoplasmic, double-membrane organelles that synthesise adenosine triphosphate (ATP). Mitochondria contain their own genome, mitochondrial DNA (mtDNA), which is maternally inherited from the oocyte. Mitochondrial proteins are encoded by either nuclear DNA (nDNA) or mtDNA, and both code for proteins forming the mitochondrial oxidative phosphorylation (OXPHOS) complexes of the respiratory chain. These complexes form a chain that allows the passage of electrons down the electron transport chain (ETC) through a proton motive force, creating ATP from adenosine diphosphate (ADP). This study aims to explore current and prospective therapies for mitochondrial disorders (MTDS). MTDS are clinical syndromes coupled with abnormalities …

Ankyrin Dependent Mitochondrial Function And Bioenergetics In The Heart, Janani Subramaniam, Janani Subramaniam

Dissertations & Theses (Open Access)

ANK2 mutations in patients are associated with numerous arrhythmias, cardiomyopathies, and other heart defects. In the heart, AnkB, the protein encoded by ANK2, clusters relevant ion channels and cell adhesion molecules in several important domains; however, its role at Mitochondria Associated ER/SR Membranes (MAMs) has yet to be investigated. MAMs are crucial to mitochondrial function and metabolism and are signaling hubs implicated in various cardiac pathologies. Among several functions, these sites mediate the direct transfer of calcium from the ER/SR to the mitochondria to modulate ATP synthesis. Given that mitochondrial function and energy production are paramount to cardiovascular heath, …

Dpc29 Promotes Mitochondrial Translation Post-Initation In Saccharomyces Cerevisiae, Kyle Andrew Hubble

Graduate School of Biomedical Sciences Theses and Dissertations

Although the cytosolic and bacterial translation systems are well studied, much less is known about translation in mitochondria. In the yeast Saccharomyces cerevisiae, mitochondrial gene expression is predominately regulated by translational activators. These regulators are thought to promote translation by binding the elongated 5’-UTRs on their target mRNAs. Since mammalian mitochondrial mRNAs generally lack 5’-UTRs, they must regulate translation by other mechanisms. As expected, most yeast translational activators lack orthologues in mammals. Recently, a mitochondrial gene-specific translational activator, TACO1, was reported in mice and humans. To better define its role in mitochondrial translation I examined the yeast TACO1 orthologue, DPC29. …

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). …

Role Of Galactose, Thiazolidinediones, And Neet Proteins In Mitochondrial Physiology And Therapeutic Development., Robert Anthony Skolik

Electronic Theses and Dissertations

This dissertation explores the relationship between mitochondrial physiology and development of therapeutics. Mitochondrial dysfunction is associated with both acute and chronic forms of pathophysiology. This work aims to address development efforts at the cell culture and drug-target levels with respect to mitochondria. At the cell culture level, I characterize an approach that has been shown to improve the physiological dependency on mitochondria in tumor-derived cells. I demonstrate that prolonged replacement of glucose with galactose in culture medium induces a global metabolic shift in hepatocellular carcinoma (HepG2) cells to closer reflect a primary hepatocyte phenotype (Chapter 2). I characterize this shift …

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 …

Review: The Bidirectional Relationship Between Mitochondrial Respiratory Chain Inhibition And Import Machinery Malfunction In Parkinson’S Disease, Grace Riggs, Deepa Dabir

Honors Thesis

Parkinson’s Disease (PD) is characterized by a loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) portion of the ventral midbrain, the region of the brain largely responsible for motor control, executive cognitive function, and emotional limbic activity (Sonne 2020). SNpc dopaminergic neurons are more vulnerable than those in other regions due to their high energy demand arising from long, highly branched, unmyelinated axons (Pissadaki & Bolam 2013). They also have a higher basal rate of oxidative phosphorylation, which has been hypothesized to further increase vulnerability in cases of PD (Pacelli et al., 2015). One of the major …

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 …

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 …

The Yeast Protein Mam33 Functions In The Assembly Of The Mitochondrial Ribosome, Gabrielle A Hillman, Michael F Henry

Rowan-Virtua School of Osteopathic Medicine Faculty Scholarship

Mitochondrial ribosomes are functionally specialized for the synthesis of several essential inner membrane proteins of the respiratory chain. Although remarkable progress has been made toward understanding the structure of mitoribosomes, the pathways and factors that facilitate their biogenesis remain largely unknown. The long unstructured domains of unassembled ribosomal proteins are highly prone to misfolding and often require dedicated chaperones to prevent aggregation. To date, chaperones that ensure safe delivery to the assembling ribosome have not been identified in the mitochondrion. In this study, a respiratory synthetic lethality screen revealed a role for an evolutionarily conserved mitochondrial matrix protein called Mam33 …

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 …

Alpha-Synuclein Toxicity Is Caused By Mitochondrial Dysfunction, Michael G. Tauro

Electronic Thesis and Dissertation Repository

Parkinson’s disease (PD) is the second most common neurodegenerative disorder, affecting roughly 1% of the population over the age of sixty years. Alpha-synuclein (aSyn) is a protein implicated in both familial and idiopathic forms of PD, yet despite the wealth of data implicating aSyn as a causative agent in PD, the mechanisms underlying its toxicity remain mostly unknown. Mitochondrial dysfunction is a major hallmark of PD, yet there is only limited evidence linking aSyn toxicity to mitochondrial dysfunction. My study establishes a novel aSyn model in respiring yeast cells, which allows me to explore how aSyn affects mitochondrial homeostasis and …

Deletion Of Mgr2p Affects The Gating Behavior Of The Tim23 Complex, Oygul Mirzalieva, Shinhye Jeon, Kevin Damri, Ruth Hartke, Layla Drwesh, Keren Demishtein-Zohary, Abdussalam Azem, Cory D. Dunn, Pablo M. Peixoto

Publications and Research

The TIM23 complex is a hub for translocation of preproteins into or across the mitochondrial inner membrane. This dual sorting mechanism is currently being investigated, and in yeast appears to be regulated by a recently discovered subunit, the Mgr2 protein. Deletion of Mgr2p has been found to delay protein translocation into the matrix and accumulation in the inner membrane. This result and other findings suggested that Mgr2p controls the lateral release of inner membrane proteins harboring a stop-transfer signal that follows an N-terminal amino acid signal. However, the mechanism of lateral release is unknown. Here, we used patch clamp electrophysiology …

Expression Of Alternative Oxidase In The Copepod T. Californicus When Exposed To Environmental Stressors, Carly Tward

Theses and Dissertations (Comprehensive)

In addition to the typical electron transport system in animal mitochondria responsible for oxidative phosphorylation, some species possess an alternative oxidase (AOX) pathway, which causes electrons to bypass proton pumping complexes. Although AOX appears to be energetically wasteful, studies have revealed its wide taxonomic distribution, and indicate it plays a role in environmental stress tolerance. AOX discovery in animals is recent, and further research into its expression, regulation, and physiological role has been impeded by the lack of an experimental model organism. DNA database searches using bioinformatics revealed an AOX sequence present in the arthropod Tigriopus californicus. Multiple sequence …

Pyronaridine Exerts Potent Cytotoxicity On Human Breast And Hematological Cancer Cells Through Induction Of Apoptosis, Paulina J. Villanueva, Alberto Martinez, Sarah T. Baca, Rebecca E. Dejesus, Manuel Larragoity, Lisett Contreras, Denisse A. Gutierrez, Armando Varela-Ramirez, Renato J. Aguilera

Publications and Research

The potent antimalarial drug pyronaridine (PND) was tested for its potential as an anticancer drug. After exposing cancerous (17) and non-cancerous (2) cells to PND for 72 hr, PND was found to exhibit consistent and potent cytotoxic activity at low micromolar (μM) concentrations that ranged from 1.6 μM to 9.4 μM. Moreover, PND exerted a significant selective cytotoxicity index (SCI) on five out of seven breast cancer cell lines tested, with favorable values of 2.5 to 4.4, as compared with the non-cancerous breast MCF-10A cell line. By using the same comparison, PND exhibited a significant SCI on three out of …

Impact Of San-Mediated Signaling On Glioblastoma And Neuroblastoma Metabolism, Monica Rodriguez Silva

FIU Electronic Theses and Dissertations

Glioblastoma (GBM) is the most common and aggressive type of brain cancer, with an average life expectancy of 15 months. The standard of care for GBM, surgery accompanied by radiation and chemotherapy (temozolomide-TMZ), has not changed in over 10 years illustrating the need for new and efficacious treatments. Therefore, it is imperative to improve our knowledge of GBM physiology to understand the mechanisms driving recurrence and chemoresistance so that more effective therapeutic options can be developed. Mitochondria-cell communication is key to monitor and maintain both mitochondrial and cellular health, and signaling events on the outer mitochondrial membrane (OMM) have emerged …

Mitochondrial Mrna Translation Is Required For Maintenance Of Oxidative Capacity, David Lee

Graduate Theses and Dissertations

Oxidative metabolism is required to produce adequate energy to sustain human life. A primary example of deteriorating oxidative capacity is seen in the cardiac musculature during chronic heart failure. This suggests that by improving oxidative potential, chronic heart disease could be mitigated and one approach to accomplish this may be through targeting the mt-mRNA translation system. Purpose: This investigation’s purpose was to characterize disruptions in mt-mRNA translation machinery in multiple forms of cardiomyopathy and to determine if mitochondrial mRNA translation initiation factor (mtIF2) is necessary to maintain oxidative capacity in cardiomyocytes. Methods Using a combination of animal and cell culture …

Mechanism Of Transcription Anti-Termination In Human Mitochondria., Hauke S Hillen, Andrey V Parshin, Karen Agaronyan, Yaroslav I Morozov, James J Graber, Aleksandar Chernev, Kathrin Schwinghammer, Henning Urlaub, Michael Anikin, Patrick Cramer, Dmitry Temiakov

Rowan-Virtua School of Osteopathic Medicine Faculty Scholarship

In human mitochondria, transcription termination events at a G-quadruplex region near the replication origin are thought to drive replication of mtDNA by generation of an RNA primer. This process is suppressed by a key regulator of mtDNA-the transcription factor TEFM. We determined the structure of an anti-termination complex in which TEFM is bound to transcribing mtRNAP. The structure reveals interactions of the dimeric pseudonuclease core of TEFM with mobile structural elements in mtRNAP and the nucleic acid components of the elongation complex (EC). Binding of TEFM to the DNA forms a downstream "sliding clamp," providing high processivity to the EC. …

Mitochondrial Damage Accumulation In Oocytes – A Potential Link Between Maternal Obesity And Increased Cardiometabolic Disease Risk In Offspring., Anna Louise Boudoures

Arts & Sciences Electronic Theses and Dissertations

The developmental origins of health and disease (DoHAD) hypothesis suggests that negative maternal lifestyle choices, such as obesity, affect the health of her offspring. Clinical and laboratory studies support this hypothesis – offspring born to obese mothers are at increased risk for health conditions including cardiometabolic syndrome and congenital abnormalities. Maternal obesity damages the oocytes, contributing to the increased disease risk by transmitting damaged organelles and epigenetic modifications to the offspring. Mitochondria, the most abundant organelle in the oocyte, are damaged in oocytes from obese females. However, we do not understand if mitochondrial damage in oocytes is reversible nor why …

Mitochondrial Dynamics Controls T Cell Fate Through Metabolic Programming, Michael Buck

Arts & Sciences Electronic Theses and Dissertations

Activated effector T (TE) cells augment anabolic pathways of metabolism, such as aerobic glycolysis, while memory T (TM) cells engage catabolic pathways, like fatty acid oxidation (FAO). However, signals that drive these differences remain unclear. Mitochondria are metabolic organelles that actively transform their ultrastructure. Therefore, we questioned whether mitochondrial dynamics controls T cell metabolism. We show that TE cells have punctate mitochondria, while TM cells maintain fused networks. The fusion protein Opa1 is required for TM, but not TE cells after infection, and enforcing fusion in TE cells imposes TM cell characteristics and enhances antitumor function. Our data suggest that, …

The Prohibitin Protein Complex Promotes Mitochondrial Stabilization And Cell Survival In Hematologic Malignancies, Elisa Robles Escajeda

Open Access Theses & Dissertations

Lymphocyte proliferation and differentiation is coordinated with high precision in healthy humans and is vital to maintaining a normal immune system. Imbalance of these events can result in the development of autoimmune diseases, immunodeficiencies and hematopoietic malignancies. These pathologies, specifically leukemia and lymphoma have a high incidence of relapse and mortality due to limited treatment options. Therefore, there is a critical need to characterize the signal transduction pathways and understand molecular hallmarks that mediate T cell activation in order to develop new strategies for diagnosis and treatments of these diseases.

Prohibitins (PHB1 and PHB2) have been proposed to play important …

Axonal Transport And Life Cycle Of Mitochondria In Parkinson's Disease Model, Hyun Sung

Open Access Dissertations

In neurons, normal distribution and selective removal of mitochondria are essential for preserving compartmentalized cellular function. Parkin, an E3 ubiquitin ligase associated with familial Parkinson’s disease, has been implicated in mitochondrial dynamics and removal. However, it is not clear how Parkin plays a role in mitochondrial turnover in vivo, and whether the mature neurons possess a compartmentalized Parkin-dependent mitochondrial life cycle. Using the live Drosophila nervous system, here, I investigate the involvement of Parkin in mitochondrial dynamics; organelle distribution, morphology and removal. Parkin deficient animals displayed less number of axonal mitochondria without disturbing organelle motility behaviors, morphology and metabolic state. …

Mir494 Reduces Renal Cancer Cell Survival Coinciding With Increased Lipid Droplets And Mitochondrial Changes, Punashi Dutta, Edward Haller, Arielle Sharp, Meera Nanjundan

Molecular Biosciences Faculty Publications

Background: miRNAs can regulate cellular survival in various cancer cell types. Recent evidence implicates the formation of lipid droplets as a hallmark event during apoptotic cell death response. It is presently unknown whether MIR494, located at 14q32 which is deleted in renal cancers, reduces cell survival in renal cancer cells and if this process is accompanied by changes in the number of lipid droplets.

Methods: 769-P renal carcinoma cells were utilized for this study. Control or MIR494 mimic was expressed in these cells following which cell viability (via crystal violet) and apoptotic cell numbers (via Annexin V/PI staining) were …

Role Of Interleukin-6 In Cd4 And Cd8 T Cell Effector Functions, Rui Yang

Graduate College Dissertations and Theses

IL-6 is an inflammatory cytokine that contributes to the pathogenesis of many immunological diseases including rheumatoid arthritis, multiple sclerosis, systemic lupus erythematosus, allergic asthma, as well as the protection against infections caused by various pathogens. These are linked to its role in regulating CD4 T cell differentiation and effector function.

Most of these functions are dependent on the IL-6-mediated signaling through the transcription factor Stat3. In this thesis, we identify a novel molecular mechanism by which IL-6 regulates CD4 T cell effector function. We show that IL-6-dependent signal raises the levels of mitochondrial Ca2+ late during activation of CD4 T …