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Loss Of Tsc2 Results In Abnormal Postnatal Neurogenesis And Striatal Hamartomas, Victoria Riley

All Dissertations

Billions of years of evolution have culminated in the most complex organ in all of biology: the brain. Its capacity to sense, store, and predict information uniquely bestows humans with the capability to generate art, music, language, and math and sets humans apart from other species. It is therefore prudent and worthwhile to study the brain and its development. A critical aspect of brain development is neurogenesis, or the production of neurons. Neurogenesis is facilitated by neural stem cells (NSCs) and is influenced by the mTORC1 signaling pathway. For NSCs to differentiate and become committed to a neuronal cell fate, …

Determining The Existence And Regulation Of Microlipophagy In Primary Brown And White Adipocytes, Sara C. Arenas De Leon

Biomedical Sciences ETDs

Lipids are one of life’s four main macromolecules and provide essential functions to cells.

The degradation of lipid droplets and mobilization of lipids occurs through lipolysis. Emerging evidence demonstrates evidence of a selective form of autophagy in lipolysis. The process of microlipophagy has only recently been described, and many features of its regulation are still poorly understood. Our recent study showed that inhibiting mammalian target of rapamycin complex 1 (mTORC1) pathway by depletion of Raptor in adipocytes led to an influx of lysosomes and accumulation of lipid droplets within lysosome. Here, we expand on these previous findings. We were able …

Determining The Existence And Regulation Of Microlipophagy In Primary Brown And White Adipocytes, Sara C. Arenas De Leon

Biomedical Sciences ETDs

Lipids are one of life’s four main macromolecules and provide essential functions to cells, as they serve as building blocks of cellular membranes, mediate cell signaling, and are a critical energy source. Within cells, esterified fatty acids aggregate into lipid droplets in the form of triglycerides, consisting of a neutral lipid core surrounded by a phospholipid monolayer decorated with various proteins.

The degradation of lipid droplets and mobilization of lipids occurs through lipolysis, a process that hydrolyzes a molecule of triglyceride into a glycerol and three fatty acids. Emerging evidence demonstrates the involvement of a selective form of autophagy in …

Inflammation And Altered Signaling In Obstetric Pathologies, Ya-Fang Tsai

Theses and Dissertations

The purpose of this research project was to elucidate the molecular interactions and detail the signaling pathways in obstetric pathologies. This work first seeks to understand inflammation related complications relevant to obstetrics. Prior research in our lab identified the implications of the receptor of advanced glycation end products (RAGE) during inflammatory response in the placenta. Current work identified the presence of DNA double-strand breaks (DNA-DSBs) in inflammation associated pregnancy complications of preeclampsia (PE) and preterm labor (PTL) and demonstrated the positive role of RAGE in repairing the damage. The confluent relevance of disrupted mitochondrial function and inflammation has been recognized …

The Effect Of Nutrition On Longevity And Fertility In Diverse Drosophila: A Tor-Mediated Process, Tessa E. Steenwinkel

Dissertations, Master's Theses and Master's Reports

Nutrition and growth are strongly linked, but not much is known about how nutrition leads to growth. To understand the connection between nutrition through diet, growth and/or proliferation, we need to study the phenotypes resulting from the activation and inhibition of central metabolic pathways. Here I use the model organism Drosophila melanogaster (D. mel.) and three non-model Drosophila species with different dietary needs, Drosophila guttifera (D. gut.), Drosophila deflecta (D. def.), and Drosophila tripunctata (D. tri.), to study the effects of dietary amino acid availability in these diverse flies on fecundity and …

Investigating The Potential Of Microbial Metabolites And Mtor Signaling On Chicken Necrotic Enteritis, Mohit Bansal

Graduate Theses and Dissertations

Necrotic enteritis (NE), caused by C. perfringens and coccidiosis, is responsible for substantial economic loss annually. In the first chapter, we investigated the effect of secondary bile acid on necrotic enteritis. Day-old broiler chicks were randomly assigned to 5 groups of diets supplemented with 0 (basal diet), 0.8, 1.0, and 1.5 g/kg (on top of basal diet) deoxycholic acid (DCA). The birds were challenged with Eimeria maxima (20,000 oocysts/bird) at d 18 and C. perfringens (109CFU/bird/day) at d 23 and d 24 to induce NE. Birds were sacrificed at d 26, and ileal tissue and digesta samples were collected. DCA …

Genetic Analysis Of Pi3k And Mtor Inhibition In U87mg Glioblastoma Cell Line, Carl G. Litif

Theses and Dissertations

NVP-BEZ235 is a Glioblastoma Multiform chemotherapeutic dual PI3K/mTOR pathway inhibitor created in 2008 and has since been proven experimentally to induce pluripotentcy in oncological cell populations. The inhibition of PI3K and mTOR has shown to coerce phenotypes associated with stem cell markers, most notably OCT4. It is necessary to understand the genetic composure of how PI3K/mTOR inhibited tumor cells are bypassing the canonical pathway for proliferation and growth and utilizing other parallel sources for tumor invasion into other neural regions. Taking a genetic approach with RNA-sequencing allowed us to gain insight into how glioblastoma interact with cytoskeleton factors MAPK4 and …

Gene Expression Regulation In The Mouse Liver By Mechanistic Target Of Rapamycin Complexes I And Ii, Anthony Poluyanoff

Masters Theses

The mechanistic target of rapamycin (mTOR) is a key serine/threonine protein kinase that functions in complexes mTORC1 and mTORC2. mTORC1, originally discovered due to its sensitivity towards the mTOR inhibitor rapamycin, responds to extracellular growth factor signaling, WNT signaling, and nutrient abundance via glucose and amino acid-triggered signaling. Downstream effectors of mTORC1 include autophagy, mitochondrial metabolic function, protein synthesis, and ribosome biogenesis. mTORC2, initially discovered as a rapamycin-insensitive complex of mTOR, responds to insulin, growth factor signaling, and inflammatory signaling such as tumor necrosis factor-alpha, with its downstream effectors being Akt, a key serine/threonine kinase that functions in cell division …

Nutrient Sensing Pathways Mediating Igfbp1 Phosphorylation In Fgr, Shapnil Bhuiyan

Electronic Thesis and Dissertation Repository

Impairment of fetal oxygen levels and nutrient delivery contributes to fetal growth restriction (FGR), which affects 20% of pregnancies. Such cellular stress induces hepatic Insulin-like Growth Factor Binding Protein 1 (IGFBP1) phosphorylation, which sequesters Insulin-like Growth Factor 1 (IGF-I) and markedly reduces fetal growth signaling. IGFBP1 hyperphosphoryaltion in hypoxia is mediated through the mTOR signaling pathway and through the Amino Acid Response (AAR) pathway during amino acid deprivation. Hypoxia stimulates upstream mTORC1 regulators, AMPK and REDD1 which are well-established upstream regulators of one of the two mTOR complexes, mTORC1. The molecular mechanisms by which upstream mTORC1-driven processes regulate IGFBP1 phosphorylation …

Amino Acid Sensing Ability By The Mechanistic Target Of Rapamycin In Oligodendrocytes, Emma England

Senior Theses and Projects

Oligodendrocytes (OLs) are a type of glial cell in the central nervous system that require substantial nutrients such as lipids and amino acids to create the extensive, metabolically expensive myelin sheath surrounding the axons of neurons. The mammalian target of rapamycin (mTOR) is a regulatory kinase that is necessary for the maturation of progenitor OLs through their distinct oligo-lineage phases. Amino acids are vital for the functioning of cells. The focus of this study was to determine if mTOR activity is dependent on the availability of leucine, methionine, and alanine. This was assessed by examining the phosphorylation level of the …

The Role Of Ifrd1 In The Recruitment And Function Of Reserve Stem Cells In Regeneration And Cancer, Mark Anthony Lewis

Arts & Sciences Electronic Theses and Dissertations

Mature cells can reprogram into a proliferative, progenitor-like state to repair tissue following injury and inflammation. Differentiated cells in diverse tissues can become proliferative via a dedicated, evolutionarily conserved program we termed paligenosis. We detailed how paligenosis occurs, in both gastric chief and pancreatic acinar cells, in a step-wise manner that involves: 1) autodegradation of mature cell components; 2) re-expression of progenitor genes; 3) re-entry into the cell cycle. This process is governed by mTORC1, a fundamental cellular energy sensor and regulator of protein translation. Blocking mTORC1 permitted autophagy and metaplastic gene induction but blocked cell cycle re-entry at S-phase. …

Translational Control Of Stress Induced Breast Cancer Plasticity, Michael Jewer

Electronic Thesis and Dissertation Repository

Cancer cell plasticity, whereby stem-cell-like properties are acquired in response to stress, represents a major challenge in cancer treatment. Using cell line and patient-derived xenograft (PDX) models, we demonstrate that translational reprogramming occurs in response to stresses such as hypoxia and chemotherapy which elicits stem cell properties in breast cancer. Other stresses like chemotherapy demonstrate the translational inhibition that has been well characterized as an integral hypoxic cellular response. The inhibition of translation is primarily regulated at initiation by mTOR/4E-BP1 and PERK/eIF2α signalling. We identify previously undescribed 5’ untranslated regions (5’UTRs) of plasticity-associated genes like NANOG, SNAIL and NODAL. …

Pas Kinase And Tor, Controllers Of Cell Growth And Proliferation, Brooke Jasmyn Cozzens

Theses and Dissertations

Nutrient sensing kinases lie at the heart of cellular health and homeostasis, allowing cells to quickly adapt to changing environments. Target of Rapamycin (TOR) and PAS kinase (PASK, or PASKIN) are two such nutrient kinases, conserved from yeast to man. In yeast, these kinases each have paralogs. The two TOR paralogs in yeast mimic the mammalian TORC1 and TORC2 complexes, except both Tor1 and Tor2 may contribute to TORC1 or TORC2 function. The two PAS kinase paralogs are paired with the TOR paralogs, meaning that both Psk1 and Psk2 regulate TORC1, while Psk2 suppresses a temperature-sensitive allele of Tor2. Herein …

Insulin-Like Growth Factor-1 Overexpression Mediates Hippocampal Remodeling And Plasticity Following Tbi, Erica Latrice Littlejohn

Theses and Dissertations--Physiology

Every year over 2.5 million traumatic brain injuries (TBI) occur and are the leading cause of death and disability among adolescents. There are no approved treatments for TBI. Survivors suffer from persistent cognitive impairment due to posttraumatic tissue damage and disruption of neural networks which significantly detract from their quality of life. Posttraumatic cognitive impairment depends in part on the brain's limited ability to repair or replace damaged cells. Immature neurons in the hippocampus dentate gyrus, a brain region required for learning and memory, are particularly vulnerable to TBI. Insulin-like growth factor-1 (IGF1) is a potential therapeutic for TBI because …

Characterization Of Notch1 And Pi3k-Pten-Akt/Mtor Pathway Interaction In Head And Neck Squamous Cell Carcinoma, Kyriante' Henry

Dissertations & Theses (Open Access)

Head and neck squamous cell carcinoma (HNSCC) affects various mucosal sites of the upper aerodigestive tract, including the nasal and oral cavities, the nasopharynx, and the oropharynx. More than five hundred thousand new cases of HNSCC occurred in 2011 alone, with 50,000 reported cases in the United States. This trend made HNSCC the seventh most common non-skin cancer worldwide (Ferlay et al., 2015). Although significant epidemiological and pathological advancements have been made, survival rates have not improved much over the last 40 years, leaving a mortality rate that remains at approximately 50%. An unbiased drug screen demonstrated that HNSCC cell …

Anti-Cancer Effects Of Tocotrienols In Nsclc, Lichchavi Raj Raj

Wayne State University Dissertations

Lung cancer is one of the leading causes of death among cancers, with non-small cell lung cancer (NSCLC) accounting for 80-85% of all lung cancers and a five-year survival rate of 5 % at stage IIIB. Delta-tocotrienol (δT) including other tocotrienol isomers has been shown to exhibit anti-tumor activity via inhibition of different signaling pathways in tumors including NSCLC. Previously we reported that δT reduced cell invasion via inhibition of the Notch-1 and NF-κb pathway.

Matrix metallopeptidase 9 (MMP9) dependent cell migration and invasion are key processes in cancer metastasis. Hence, its suppression is a promising strategy for cancer therapeutics. …

Concomitant Targeting Of The Mtor/Mapk Pathways: Novel Therapeutic Strategy In Subsets Of Non-Small Cell Lung Cancer, Dennis Ruder

Dissertations & Theses (Open Access)

Over the last decade, a paradigm-shift in lung cancer therapy has evolved into targeted-driven medicinal approaches. However, patients frequently relapse and develop resistance to available therapies. Herein, we utilized genomic mutation data from advanced chemorefractory non-small cell lung cancer (NSCLC) patients enrolled in the Biomarker-Integrated Approaches of Targeted Therapy for Lung Cancer Elimination (BATTLE-2) clinical trial to characterize novel actionable genomic alterations potentially of clinical relevance. We identified RICTOR alterations (mutations, amplifications) in 17% of lung adenocarcinomas and found RICTOR expression correlates to worse overall survival. There was enrichment of MAPK pathway genetic aberrations in key oncogenes (e.g. KRAS, BRAF, …

Effect Of Rapamycin As An Inhibitor Of The Mtor Cell Cycle Entry Complex On The Selective Lysis Of Human Leukemia Cells Lines In Vitro Using 20 Khz Pulsed Low-Frequency Ultrasound, Yasmine Hemida

Honors Capstone Projects - All

It has been shown that the mammalian target of rapamycin (mTOR) pathway, which regulates cell growth and proliferation, is aberrant in many hematological malignancies. Rapamycin inhibits mTOR signaling which regulates cell growth and cell cycle progression. This study sought to determine the effects of mTOR inhibitors on the cell sizes of normal and neoplastic cells and to determine ultrasonic sensitivity of normal and neoplastic cells treated with mTOR inhibitors. The effects of rapamycin (rapa), an extensively studied natural product that affects cell cycle entry by inhibiting mTORC1, and its analogs temsirolimus (tems) and everolimus (eve), were examined on leukemic cell …

The Impact Of Folate Restriction On Cancer And Aging: A Mechanistic Analysis, Safa Beydoun

Wayne State University Dissertations

Aging is a multifactorial process associated with alterations in several physiological functions. It increases susceptibility to disease and ultimately results in mortality. Since the associated diseases of aging are highly prevalent in the geriatric population, targeting the aging process as a whole may provide a better way to delay these age related diseases, in turn delaying aging. Various interventions have been shown to delay aging and age related diseases. They impact a major nutrient sensing pathway, mTOR. mTOR signaling is altered in many cancers and its downregulation was shown to delay aging. Other interventions extend lifespan by altering the one …

Metabolomics Of Mammalian And Cellular Models Of Aging, Nathan Gonzales Duval

Electronic Theses and Dissertations

Aging is often associated with impaired cognition and a progressive loss of organ function over time accompanied by an increased susceptibility for many disorders, including Alzheimer's disease (AD), Parkinson's disease (PD), heart disease, osteoporosis, type II diabetes, and many forms of cancer. With a rapidly aging population, the negative impacts of aging and age-related disorders is a major cause of increased human suffering both for affected individuals and for families and caregivers. Metabolic changes are also apparent in normal aging, but may increase in magnitude or nature with accompanying disease states or with accelerated aging. Thus, studying aging in a …

Molecular Mechanisms Linking Amino Acid (Leucine) Deprivation To Igfbp-1 Hyperphosphorylation In Fetal Growth Restriction, Niyati M. Malkani

Electronic Thesis and Dissertation Repository

In this study, we explore the molecular mechanisms linking amino acid (leucine) deprivation to IGFBP-1 hyperphosphorylation in vitro. During pregnancy, a maladaptive fetal response to in utero amino acid deprivation leads to Fetal Growth Restriction (FGR). FGR infants display elevated phosphorylated IGFBP-1, which is associated with decreased IGF-I bioavailability. Leucine deprivation inhibits mechanistic target of rapamycin (mTOR) signaling and stimulates the amino acid response (AAR). Using HepG2 cells, a model for fetal hepatocytes, we demonstrate that in leucine deprivation, the AAR modulates total and phosphorylated IGFBP-1 while mTOR mediates total IGFBP-1 secretion only. We also reveal that protein kinases …

The Role Of Autophagy In The Sensitivity Of Osteosarcoma Cells To Gemcitabine Treatment, Janice M. Santiago-O'Farrill

Dissertations & Theses (Open Access)

Despite treatment improvement for osteosarcoma (OS), overall survival has remained unchanged in the last 20 years. Pulmonary metastasis continues to be the main cause of death; novel therapeutic strategies are urgently needed to improve the survival rate of these patients. Previous data in our laboratory has demonstrated that aerosol gemcitabine (GCB) treatment has a significant therapeutic effect on metastatic OS. However, treatment efficacy is decreased due to acquired resistance by a population of tumor cells that fails to respond to treatment. Recent studies have implicated autophagy as a resistance mechanism in various types of cancer. The purpose of this study …

Mtor Signaling And Endoplasmic Reticulum Stress In Mixed Glial Cultures, William Theodore Schreiber-Stainthorp

Senior Theses and Projects

Oligodendrocytes are the myelinating cells of the central nervous system. The extraordinary protein and lipid synthesis that myelin production entails makes oligodendrocytes especially prone to endoplasmic reticulum (ER) stress. In this experiment, we set out to investigate the dynamics of ER stress in mixed glial cultures, and how the consequences of that stress vary based on the activity of the anabolic PI3K/AKT/mTOR pathway. Previous experiments in isolated oligodendrocyte cultures demonstrated a negative correlation between AKT/mTOR signaling and oligodendrocyte cell viability in the presence of ER stressors. Because ER stress leads to a buildup of improperly processed proteins, decreases in mTOR …

The Endosomal Sorting Complex Required For Transport Pathway Mediates Chemokine Receptor Cxcr4 Akt Signaling By Promoting Lysosomal Degradation Of Mtor Antagonist Deptor, Rita Ramkaran Verma

Dissertations

The chemokine receptor CXCR4 is a member of the G protein-coupled receptor (GPCR) family. The cognate ligand for CXCR4 is the C-X-C chemokine known as CXCL12. The CXCL12/CXCR4 signaling axis is essential for a number of developmental processes including organogenesis, vascularization of the GI tract and hematopoiesis. Dysregulated CXCR4 signaling is also implicated in a variety of pathological conditions such as WHIM (Warts, Hypogammaglobunemia, Infections and myelokathexis) syndrome, cardiovascular disease and cancer. Despite its role in several pathologies, the molecular mechanisms mediating CXCR4 signaling are not completely understood. Upon CXCL12 binding to CXCR4, several signaling pathways are activated including the …

Desensitization Of Hacat Keratinocytes To Vitamin D3 Occurs Via Loss Of Redd1 Regulation Of The Mtor Pathway, Michelle Leigh Jones

Wayne State University Theses

Vitamin D3 treatment has long been considered in the treatment of cancer due to its well-documented anti-proliferative effects in vitro. While clinical studies have been positive in other cancers, results are inconclusive in cases of basal cell carcinoma. To better understand the reasons underlying this disconnect, this study employs an immortalized human keratinocyte cell line (HaCaT) to observe the effects of vitamin D3 treatment on cellular proliferation. The results show that both activate vitamin D3 (calcitriol) and its precursor (cholecalciferol) increase proliferation of these cells. Real-time PCR and western blot data indicate that the mTOR pathway becomes activated despite increased …

Regulation Of Igfbp-1 Phosphorylation In Hypoxia Via Mtor Signaling, Ian Damerill

Electronic Thesis and Dissertation Repository

In this study, we provide novel evidence for a role of fetal liver mTOR signaling in regulating IGF-I bioavailability by modulating IGFBP-1 phosphorylation due to hypoxia – a key factor in the development of reduced fetal growth in utero. We utilized HepG2 cells in vitro and demonstrated a link between mTOR inhibition and hypoxia-induced IGFBP-1 phosphorylation. Using a biological assay for IGF-I receptor autophosphorylation, we demonstrated a functional significance for hypoxia-induced IGFBP-1 phosphorylation in reducing IGF-I bioactivity in vitro. Further, we have implicated a mechanistic link to increased CK2 activity within this regulation. We demonstrate that mTOR inhibition …

Non-Canonical Notch Signaling Regulates Activation And Differentiation Of Peripheral Cd4+ T Cells, Anushka Dongre

Doctoral Dissertations

Cleavage of the Notch receptor via a γ-secretase, results in the release of the active intra-cellular domain of Notch that migrates to the nucleus and interacts with RBP-J_Κ, resulting in the activation of downstream target genes. This canonical Notch signaling pathway has been documented to influence T-cell development and function. However, the mechanistic details underlying this process remain obscure. In addition to RBP-J_Κ, the intra-cellular domain of Notch also interacts with other proteins in the cytoplasm and nucleus, giving rise to the possibility of an alternate, RBP-J_Κ independent Notch pathway. However, the contribution of such RBP-J …

Pi3k- And Mtor-Dependent Mechanisms Of Lapatinib Resistance And Resulting Therapeutic Opportunities, Samuel Brady

Dissertations & Theses (Open Access)

Breast cancers with HER2 amplification represent 20-25% of breast cancer cases and are frequently responsive to the HER2 kinase inhibitor lapatinib, but generally for only short duration. We aimed to understand how breast cancers with HER2 amplification become resistant to lapatinib, in order to identify potential therapies that can overcome lapatinib resistance. To establish lapatinib resistance models we treated three HER2+ breast cancer cell lines with lapatinib for several months until they became lapatinib-resistant. We then compared lapatinib-sensitive (parental) cells with their lapatinib-resistant (LapR) counterparts to identify changes conferring lapatinib resistance. We found that activation of PI3K, specifically the p110α …

Strategies To Sensitize Bladder Cancer Cells To Small Molecule Inhibitors Targeting The Pi3k Pathway, Giovanni Nitti

Dissertations & Theses (Open Access)

After many years of cancer research, it is well accepted by the scientific community that the future cure for this disease lies in a personalized therapeutic approach. Anticipating therapeutic outcome based on the genetic signature of a tumor has become the new paradigm. The PI3K pathway represents an ideal target for bladder cancer, as many of the key proteins of this pathway are altered or mutated in this particular type of cancer. Several small molecule inhibitors have been developed to target this pathway, but their efficacy has been shown to be heterogeneous among different cell lines and mostly cytostatic but …

Examination Of Anabolic Signaling And Muscle Growth With Caffeine Treatment In Overloaded Hindlimb Muscle And Electrically Stimulated Muscle Lacking Liver Kinase B1, Timothy Michael Moore

Theses and Dissertations

Skeletal muscle has the ability to increase in size (hypertrophy) after resistance is placed upon it. This hypertrophy is marked by significant upregulation of the mammalian target of rapamycin (mTOR) and its downstream targets. The upstream kinases, protein kinase B (also known as Akt) and AMP-activated protein kinase (AMPK), are two of the many regulators of the mTOR pathway. Recent studies suggest that the widely consumed neuroactive compound caffeine could potentially inhibit mTOR by acting through Akt and/or AMPK. The purpose of this thesis was to: 1) determine if caffeine can inhibit the mTOR pathway and ultimately attenuate skeletal muscle …