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The Anti-Diabetic Drug Metformin Disrupts Feeding And Sleeping Behaviors In Drosophila Melanogaster., Lucas Fitzgerald

College of Arts & Sciences Senior Honors Theses

Dimethylbiguanide, also known as metformin, is the single most prescribed oral treatment for non-insulin dependent diabetes mellitus, or type 2 diabetes, in Western countries. The primary mechanism of action that metformin acts through is the activation of AMP kinase, an important regulator of energy homeostasis. While the anti-diabetic effects of metformin are well documented, its effects on feeding and sleeping behaviors are not well characterized. Using the model organism Drosophila melanogaster, the mean daily quantity of food consumed was measured and compared between groups treated with several dosages of metformin. Feeding interactions such as meal frequency and length were …

Ampk Signalling As A Regulator Of Autophagy In A Model Of Ovarian Tumour Dormancy, Jeremi Laski

Electronic Thesis and Dissertation Repository

One of the hallmarks of epithelial ovarian cancer (EOC) metastasis lies in the process of spheroid formation, whereby tumour cells aggregate into 3D structures. Previous literature suggests that as EOC cells form spheroids they undergo bioenergetic stress, activate AMP-activated protein kinase (AMPK) signaling, and thereby force cells to enter a metabolically quiescent state. We have previously shown that EOC spheroids up- regulate autophagy, a process that provides energy during starvation conditions. Herein, I examined the role of AMPK-mediated signaling regulation of autophagy in a model of ovarian tumour dormancy. Attenuation of AMPK signaling in EOC spheroids resulted in reduction of …

Regulation Of Canonical And Non-Canonical Hippo Pathway Components In Mitosis And Cancer, Seth Stauffer

Theses & Dissertations

The Hippo pathway is conserved regulator of organ size through control of proliferation, apoptosis, and stem-cell self-renewal. In addition to this important function, many of the canonical signaling members have also been shown to be regulated during mitosis. Importantly, Hippo pathway components are frequently dysregulated in cancers and have attracted attention as possible targets for improved cancer therapeutics. Further exploration of Hippo-YAP (yes-associated protein) signaling has revealed new regulators and effectors outside the canonical signaling network and has revealed a larger non-canonical network of signaling proteins in which canonical Hippo pathway components crosstalk with important cellular homeostasis and apoptosis signaling …

Functional Signature Ontology-Based Identification And Validation Of Novel Therapeutic Targets And Natural Products For The Treatment Of Cancer, Beth Neilsen

Theses & Dissertations

Multiple studies have revealed that Ras-driven tumors acquire vulnerabilities by adapting cellular mechanisms that promote uncontrolled proliferation and suppress apoptosis. Kinase Suppressor of Ras 1 (KSR1) modulates ERK activation downstream of oncogenic Ras, and knockdown of KSR1 selectively kills malignant, Ras-driven cancer cells, but does not kill immortalized, non-transformed human colon epithelial cells (HCECs). KSR1^-/- mice are fertile and phenotypically normal, but resistant to Ras-driven tumor formation suggesting KSR1 represents a vulnerability in cancer cells.

To identify additional vulnerabilities in cancer, a screening approach termed Functional Signature Ontology (FUSION) was used to screen 14,355 genes and 1,200 natural product …

Carbohydrate-Based Inducers Of Cellular Stress For Targeting Cancer Cell Metabolism, Fidelis Ndombera

Wayne State University Dissertations

ABSTRACT

CARBOHYDRATE-BASED INDUCERS OF CELLULAR STRESS FOR TARGETING CANCER CELL METABOLISM

by

FIDELIS TOLOYI NDOMBERA

May 2018

Advisor: Dr. Young-Hoon Ahn

Major: Chemistry (Biochemistry)

Degree: Doctor of Philosophy

Metabolic reprogramming and redox control of cancer cells is vital for their proliferation, but also provides selective strategies for treating cancer. Increased generation of reactive oxygen species (ROS) and an intricate control of redox status in cancer cells relative to normal cells provide a basis for designing ROS-inducing anticancer agents. In my work, I designed, synthesized and evaluated carbohydrate-based small molecules for ROS-generation, cytotoxicity and redox signaling and stress response. Our data …

Insights Into The Therapeutic Potential Of Salt Inducible Kinase 1: A Novel Mechanism Of Metabolic Control, Randi Fitzgibbon

Dissertations & Theses (Open Access)

Salt inducible kinase 1 (SIK1) has been considered a stress-inducible kinase since it was first cloned in 1999. Continued efforts since this time have been dedicated to characterizing the structure and function of SIK1. Such research has laid the ground work for our understanding of SIK1 action and regulation in tissue and stimuli dependent manners. The fundamental findings of this dissertation continue in this tradition and include investigations of SIK1 regulatory mechanisms in skeletal muscle cells, the cellular and physiological effects of SIK1 loss of function in vitro and in vivo, and intracellular metabolic and mitochondrial regulation by this …

Identification Of Oxygen Optima For Mouse Trophoblast Stem Cells And Human Embryos And The Stress Responses Upon Departing Optima, Yu Yang

Wayne State University Dissertations

Low level of oxygen (O2) occurs physiologically during in vivo embryo development. As developing embryos moving from fallopian tube to uterus, oxygen level gradually decreases to ≤ 5% at the time of blastocyst implantation. Blastocysts are made of two major cell populations, trophoblast cells and inner cell mass, from which trophoblast stem cells (TSCs) and embryonic stem cells (ESCs) are derived respectively. TSCs serve as placental stem cells that later on proliferate and differentiate into placenta. Previous study has shown that 2% O2 is the optimal O2 level for mTSC in vitro growth and potency maintenance, which agrees with their …

The Role Of Amp-Activated Protein Kinase (Ampk) In Tumorigenesis, Fei Han

Dissertations & Theses (Open Access)

AMPK plays a central role in controlling cellular and whole body energy level. Increasing studies have also discovered the diverse function of AMPK in cancer, such as autophagy and mitochondria biogenesis. However, how AMPK promotes cancer progression is still not clear. Here, we show that AMPK is essential for EGF-induced Akt activation, Glut1 expression, and glucose uptake. AMPK is also required for various stresses induced Akt activation and promote cell survival, including hypoxia and glucose deprivation. In addition, we found glucose deprivation-induced VEGF expression and secretion is also depend on AMPK, which may contribute to angiogenesis of surrounding endothelial cell …

Understanding The Role Of Sumoylation In Regulating Lkb1 Function, Joan W. Ritho

Dissertations & Theses (Open Access)

Energy homeostasis in a cell is critical for its survival during metabolic stress. Liver kinase B1 (LKB1), one of the key regulators of cellular energy balance, was initially discovered as a tumor suppressor mutated in patients with Peutz-Jeghers syndrome. Germline mutations in LKB1 predispose patients to develop several benign and malignant tumors including gastrointestinal and lung cancers. In 2003, several groups demonstrated that LKB1is a major upstream kinase of the energy sensor AMP-activated protein kinase (AMPK), directly associating it with the regulation of energy balance in cells. During energy stress, LKB1 phosphorylates AMPK at threonine 172 (T172) resulting in AMPK …

Proteasome Inhibition As A Potential Anti-Breast Cancer Therapy: Mechanisms Of Action And Resistance-Reversing Strategies, Rahul Rajesinh Deshmukh

Wayne State University Dissertations

AMPK activation and Ubiquitin Proteasome System (UPS) inhibition have gained great attention as therapeutic strategies for the treatment of certain types of cancers. While AMPK serves as a master regulator of cellular metabolism, UPS regulates protein homeostasis. Although the crosstalk between them is suggested, the relationship between these two important pathways is not very clear. We observed that proteasome inhibition leads to AMPK activation in human breast cancer cells. We report that a variety of proteasome inhibitors activate AMPK in all of the tested cancer cell lines. Our data using Liver Kinase B1 (LKB1)-deficient cancer cells suggests that proteasome inhibitor-induced …

Rheb Dynamics On Lysosomal Membranes Determines Mtorc1 Activity After Loss Of P53 Or Activation Of Ampk, Catherine M. Bell

Theses and Dissertations

The tumor suppressor TP53 is the most frequently altered gene in human cancers. The growth-promoting complex, mTORC1 plays a part of the oncogenic profile caused by dysfunctional p53. mTORC1 sits downstream of AMPK and other crucial tumor suppressors/oncogenes, PTEN, LKB1, and Akt. The antifolate pemetrexed was found by this laboratory to activate AMPK via the inhibition of the enzyme AICART in de novo purine synthesis. This work presents a mechanism of mTORC1 activation with p53 loss, as well as of mTORC1 inhibition by pemetrexed-induced AMPK. We have found that mTORC1 activity was substantially upregulated by the loss …

Pemetrexed, A Modulator Of Amp-Activated Kinase Signaling And An Inhibitor Of Wild Type And Mutant P53, Stuti Agarwal

Theses and Dissertations

New drug discoveries and new approaches towards diagnosis and treatment have improved cancer therapeutics remarkably. One of the most influential and effective discoveries in the field of cancer therapeutics was antimetabolites, such as the antifolates. The interest in antifolates increased as some of the antifolates showed responses in cancers, such as mesothelioma, leukemia, and breast cancers. When pemetrexed (PTX) was discovered, our laboratory had established that the primary mechanism of action of pemetrexed is to inhibit thymidylate 22 synthase (TS) (E. Taylor et al., 1992). Preclinical studies have shown that PTX has a broad range of antitumor activity in human …

Lkb1 Deficient Non-Small Cell Lung Cancer Cells Are Vulnerable To Energy Stress Induced By Atp Depletion, Chao Yang

Dissertations & Theses (Open Access)

Lung cancer is the second most frequent cancer in United States, which represents about 13.5% of new cancer cases every year. It accounts for about 27.2% of all cancer related deaths, which is more than the sum of deaths caused by prancretic, breast and colorectal. On average, only about 16% of lung cancer patients survive beyond 5 years. LKB1 is the third most mutated gene in lung cancer. It has been shown that LKB1 is mutated in at least 15% to 30% of NSCLC. Tumor with LKB1 mutation is associated with poor differentiation, high metastasis and worse response to chemotherapy. …

Novel Posttranslational Modification In Lkb1 Activation And Function, Szu-Wei Lee

Dissertations & Theses (Open Access)

Cancer cells display dramatic alterations in cellular metabolism to meet their needs of increased growth and proliferation. In the last decade, cancer research has brought these pathways into focus, and one emerging issue that has come to attention is that many oncogenes and tumor-suppressors are intimately linked to metabolic regulation (Jones and Thompson, 2009). One of the key tumor-suppressors involved in metabolism is Liver Kinase B1 (LKB1). LKB1 is the major upstream kinase of the evolutionarily conserved metabolic sensor—AMP-activated protein kinase (AMPK). Activation of the LKB1/AMPK pathway provides a survival advantage for cells under energy stress. LKB1 forms a heterotrimeric …

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 …

The Effects Of Aging On Skeletal Muscle Ampk Activation And An Analysis Of Chronic Aicar Treatment On The Aging Phenotype, Shalene E. Hardman

Theses and Dissertations

AMP-activated protein kinase (AMPK), a metabolic regulator, acts in opposition to many of the effects of aging and may provide insights into the development of sarcopenia. However, the effect of aging on AMPK activation is unclear. The purpose of this dissertation was to: 1) clarify the controversy concerning the activation of AMPK in response to endurance-like exercise in aged skeletal muscle; 2) address mechanisms for the age-associated alterations in AMPK activation; and 3) address the known benefits of chronic AICAR treatment in aged skeletal muscle. First, to clarify the effect of age on AMPK activation, young adult (YA) (8 mo.) …

Iron Deficiency Causes A Shift In Amp-Activated Protein Kinase (Ampk) Catalytic Subunit Composition In Rat Skeletal Muscle, John Merrill

Theses and Dissertations

To determine effects of iron deficiency on AMPK activation and signaling, as well as the AMPKα subunit composition in skeletal muscle, rats were fed a control (C=50-58 mg/kg Fe) or iron deficient (ID=2-6 mg/kg Fe) diet for 6-8 wks. Their respective hematocrits were 47.5% ± 1.0 and 16.5% ± 0.6. Iron deficiency resulted in 28.3% greater muscle fatigue (p<0.01) in response to 10 min of stimulation (1 twitch/sec) and was associated with a greater reduction in phosphocreatine (C: Resting 24.1 ± 0.9 micromol/g, Stim 13.1 ± 1.5 micromol/g; ID: Resting 22.7 ± 1.0 micromol/g, Stim 3.2 ± 0.7 micromol/g; p<0.01) and ATP levels (C: Resting 5.89 ± 0.48 micromol/g, Stim 6.03 ± 0.35 micromol/g; ID: Resting 5.51 ± 0.20 micromol/g, Stim 4.19 ± 0.47 micromol/g; p<0.05). AMPK activation increased with stimulation in muscles of C and ID animals. A reduction in Cytochrome c and other iron-dependent mitochondrial proteins was observed in ID animals (p<0.01). The AMPK catalytic subunit (alpha) was also examined because both isoforms are known to play different roles in responding to energy challenges. In ID animals, AMPK alpha2 subunit protein content was reduced to 71.6% of C (p<0.05), however this did not result in a significant difference in resting AMPK alpha2 activity. AMPK alpha1 protein was unchanged, however an overall increase in AMPK alpha1 activity was observed (C: 0.91 pmol/mg/min; ID: 1.63 pmol/mg/min; p<0.05). Resting phospho Acetyl CoA Carboxylase (pACC) was unchanged. This study indicates that chronic iron deficiency causes a shift in the expression of AMPK alpha subunit composition and potentially altered sensitivity to cellular energy challenges.

Characterization Of The Lkb1-Mo25-Strad Ampkk Complex In Adult Mouse Skeletal Muscle, Cody Don Smith

Theses and Dissertations

In liver tissue, the AMP-activated protein kinase kinase (AMPKK) complex was identified as the association of LKB1, MO25α/β, and STRADα/β proteins; however, this complex has yet to be characterized in skeletal muscle. In this report, we demonstrate the expression of the LKB1-MO25-STRAD AMPKK complex in adult skeletal muscle, confirm the absence of mRNA splice variants, and report the relative mRNA expression levels of these complex-forming proteins. To facilitate this characterization we used control (ctrl) and muscle-specific LKB1 knockout (LKB1-/-) mice. LKB1 detection in untreated ctrl and LKB1-/- muscle lysates revealed two protein bands at approximately 50 and 60 kDa; although, …

Role Of Ampk In The Upregulation Of Steroidogenic Acute Regulatory Protein In The Zona Fasciculata Of The Adrenal Cortex, Adam Wesley Dayton

Theses and Dissertations

Cortisol is a glucocorticoid produced by the zona fasciculata (ZF) of the adrenal cortex. Traditionally, cortisol production and release was seen as being regulated strictly by adrenocorticotropic hormone (ACTH). While this is true of baseline cortisol levels and in response to acute mental stress, the picture is somewhat more complicated in other situations.Interleukin-6 (IL-6) contributes to the maintenance of cortisol levels in situations of prolonged immune or inflammatory stress. AMP activated protein kinase (AMPK) was investigated as a possible mediator of the action of IL-6 or as an independent actor in raising cortisol levels in response to hypoxemic or hypoglycemic …

The Effects Of Excess Corticosterone On Lkb1 And Ampk Signaling In Skeletal Muscle Of Rats, Gary N. Nakken

Theses and Dissertations

Cushing's syndrome and glucocorticoid therapy lead to central obesity, insulin resistance, and symptoms of altered energy regulation similar to those observed in the metabolic syndrome. We hypothesized that excess glucocorticoids alter energy sensing/signaling in skeletal muscle through mediation of the LKB1/AMPK signaling pathway. To test this hypothesis, three 100 mg pellets of corticosterone were implanted subcutaneously in each of nine rats for two weeks. Responses were compared with sham operated controls fed ad libitum or food restricted to produce the body weights similar to the treatment group rats. After the treatment period, animals were anesthetized and the right gastrocnemius-plantaris and …

Effects Of Endurance Training On The Ampk Response To Exercise., David Gerald Chesser

Theses and Dissertations

Activation of AMP-activated protein kinase (AMPK) results in the upregulation of several intracellular systems which help to prepare a cell for a high energy challenge. The magnitude of the AMPK response to a 10 min bout of exercise has been found to decrease in red quadriceps (RQ) following training, while putative AMPK roles seem to be maintained; specifically, the biogenesis of mitochondria and higher levels of hexokinase II and glucose transporter 4 (GLUT4). If the AMPK response to exercise is responsible in part for these adaptations, how can they be maintained if the AMPK response is attenuated? The purpose of …

Amp-Activated Protein Kinase Kinase Activity And Phosphorylation Of Amp-Activated Protein Kinase In Contracting Muscle Of Sedentary And Endurance Trained Rats, Denise Hurst

Theses and Dissertations

This study was designed to examine activity of AMP-activated protein kinase kinase (AMPKK) and AMP-activated protein kinase (AMPK) in muscles from control (C) and endurance trained (T) rats. Rats were trained 5 days/wk, 2 hr/d for 8 wks at a final intensity of 32 m/min up a 15% grade with 30 second sprints at 52 m/min every 10 min. Gastrocnemius muscles were stimulated in situ in T and C rats for 5 min at frequencies of 0.4/sec and 1/sec. Gastrocnemius LKB1 protein, a putative component of the AMPKK complex (LKB1, STRAD, and MO25), increased approximately 2-fold in response to training. …

Regulation Of Lkb1-Strad-Mo25 Complex Expression And Activation Of Ampk In Skeletal Muscle By Thyroid Hormone, Devon Jack Branvold

Theses and Dissertations

AMP-activated protein kinase (AMPK), a heterotrimeric protein which serves as a metabolic master switch in skeletal muscle, is a research target for the pharmaceutical treatment and prevention of type 2 diabetes. The expression of all of the isoforms of the subunits of AMPK and AMPK activity are increased in skeletal muscle tissue of hyperthyroid rats. Activity of AMPK is regulated by an upstream kinase (AMPKK). The LKB1-STRAD-MO25 complex is a major AMPKK in skeletal muscle. This experiment was designed to determine whether the increase in AMPK activity is accompanied by a thyroid hormone-induced increase in the expression of the LKB1-STRAD-MO25 …

The Effects Of 3-Phosphoglycerate And Other Metabolites On The Activation Of Amp-Activated Protein Kinase By Lkb1/Strad/Mo25, William John Ellingson

Theses and Dissertations

Skeletal muscle contraction results in the phosphorylation and activation of the AMP-activated protein kinase (AMPK) by an upstream kinase, AMPKK. The LKB1-STRAD-MO25 complex is the major AMPKK in skeletal muscle; however, LKB1-STRAD-MO25 activity is not increased by muscle contraction. This relationship suggests that phosphorylation of AMPK by LKB1-STRAD-MO25 during skeletal muscle contraction may be regulated by allosteric mechanisms. In this study we tested an array of metabolites including glucose-6-phosphate (G6P), fructose-6-phosphate (F6P), fructose 1,6-bisphosphate (F1,6-P2), 3-phosphoglycerate (3PG), glucose-1-phosphate (G1P), glucose-1,6-bisphosphate (G1,6-P2), adenosine diphosphate (ADP), carnitine (Carn), acetyl-carnitine (Acarn), inosine monophosphate (IMP), inosine, and ammonia for allosteric regulation. We found that …

Pka As An Upstream Kinase For Lkb1/Strad/Mo25, Seth Taylor Herway

Theses and Dissertations

The LKB1/STRAD/MO25 complex (LSMK) has been identified as the major upstream kinase for AMP-activated protein kinase (AMPK). PKA phosphorylates LKB1 at the Ser428 residue in humans and Ser431 residue in mice. We investigated PKA as an upstream kinase for LSMK. LKB1 that had been incubated with PKA prior to incubation with AMPK experienced up to a 51% increase in AMPK Kinase activity compared to LKB1 alone (p < 0.05). When blocked with a PKA Inhibitor, the kinase effect of PKA on LKB1 was eliminated. Rat epitrochlearis muscle tissue incubated with epinephrine experienced no increase in AMPK activity compared with controls indicating that epinephrine does not cause AMPK activity in this type of tissue. In conclusion, phosphorylation by PKA can increase the AMPKK activity of LKB1-STRAD-MO25 in vitro. Because LKB1 has been found to be constitutively active, it is postulated that phosphorylation by PKA may act to enhance LKB1-AMPK interaction and thus achieve its effect.