Biochemical Phenomena, Metabolism, and Nutrition Commons^™

Impaired Mitochondrial Magnesium Transport Induces Genome-Wide Transcriptional Changes In Hepatic Steatosis, Inflammatory Signaling, And Detoxification Pathways During High-Fat Diet Feeding, Abhishek Shastry, Thiruvelselvan Ponnusamy, Asha Parveen Sakkarai Mohamed, Marianne Assogba, Natarajaseenivasan Kalimuthusamy, Shanmughapriya Santhanam

Rowan-Virtua Research Day

Calcium overload during fatty diet consumption induces oxidative stress and mitochondrial apoptosis. Intramitochondrial magnesium inhibits calcium uptake into mitochondria; therefore, modulating the activity of the mitochondrial magnesium transporter Mrs2 may regulate calcium-induced hepatocellular stress. As previous work demonstrates that liver-specific Mrs2 inhibition increases hepatic lipid deposition, RNA-sequencing was performed to identify potential transcriptional mechanisms for hepatocellular stress.

Mrs2 knockout (Mrs2^KO) mice were generated by crossing male Mrs2^fl/fl mice with liver-specific-Cre transgenic mice. Eight-week-old wild-type (Mrs2^WT) and Mrs2^KO mice were placed on chow or high-fat diet (HFD) for 12 months (n=3/group). Whole liver was collected …

Long Acting Beta2-Adrenergic Receptor Agonists Reverse Diabetic Nephropathy And Liver Steatosis In Murine Models Of Diabetes And Are Associated With Protection In Retrospective Human Studies, Brennan Winkler

MUSC Theses and Dissertations

Diabetes Mellitus (DM) affects 13.9% of men and 14.3% of women worldwide, a total of approximately 828 million people. Patients with diabetes are at risk of several complications including diabetic nephropathy (DN) and metabolic-associated steatohepatitis (MASH). These diseases eventually lead to end stage kidney disease (ESKD) and liver failure requiring dialysis and organ transplantation. In addition, diabetes exacerbates disease severity of autosomal dominant polycystic kidney disease (ADPKD), the most common potentially lethal genetic disease to affect humans with a prevalence of 1 in 500-1000. Therefore, a therapeutic approach that can attenuate organ damage and restore function in patients with DM, …

Alcohol And Metabolic Stress Synergize To Dysregulate Mitochondrial Health And Lipid Metabolism; Evidence From A Hepatocyte Spheroid Model, Eden M. Gallegos, Kaitlin Couvillion, Drake Darden, Keishla Rodriguez-Graciani, Patricia E. Molina, Liz Simon

School of Graduate Studies Faculty Publications

Metabolic dysfunction-associated steatotic liver disease and alcohol-associated liver disease frequently co-occur, manifesting as MetALD. Understanding the hepatocyte-specific effects of alcohol and metabolic stressors is critical to uncovering mechanisms of synergistic injury. This study evaluated the individual and combined effects of ethanol, sugars, and saturated/monounsaturated fats on hepatocyte lipid metabolism, oxidative stress, and mitochondrial function using a 3D human HepaRG spheroid model. HepaRG spheroids were treated with ethanol (50 mm), sugar (glucose and fructose), and fatty acids alone or in combination for 10 d. The combination of ethanol (E) and metabolic (sugar and fat, SF) stressors (ESF) synergistically increased triglyceride content …

Integrated Systems Biology Identifies Disruptions In Mitochondrial Function And Metabolism As Key Contributors To Hfpef, Andrew A. Gibb, Kyle Lapenna, Ryan B. Gaspar, Nadina R. Latchman, Yinfei Tan, Carmen Choya-Foces, Jake E. Doiron, Zhen Li, Huijing Xia, Michael P. Lazaropoulos, Mariell Conwell, Thomas E. Sharp, Traci T. Goodchild, David J. Lefer, John W. Elrod

School of Graduate Studies Faculty Publications

Heart failure with preserved ejection fraction (HFpEF) accounts for ∼50% of HF cases. The ZSF1-obese rat model recapitulates clinical features of HFpEF including hypertension, obesity, metabolic syndrome, exercise intolerance, and diastolic dysfunction. We utilized a systems-biology approach to define the metabolic and transcriptional signatures to gain mechanistic insight into pathways contributing to HFpEF development. Male ZSF1-obese, ZSF1-lean hypertensive controls, and WKY (wild-type) controls were compared at 14 weeks of age for extensive physiological phenotyping and left ventricle (LV) tissue harvesting for unbiased-metabolomics, RNA-sequencing, and mitochondrial morphology and function. Utilizing ZSF1-lean and WKY controls enabled a distinction between hypertension-driven molecular changes …

Oxidized Carbon Nanoparticles Enhance Cellular Energetics With Application To Injured Brain, Karthik Mouli, Anton V Liopo, Emily A Mchugh, Erica Underwood, Jing Zhao, Pramod K Dash, Anh T T Vo, Vikas H Malojirao, Muralidhar L Hegde, James M Tour, Paul J Derry, Thomas A Kent

Faculty, Staff and Student Publications

Pro-energetic effects of functionalized, oxidized carbon nanozymes (OCNs) are reported. OCNs, derived from harsh acid oxidation of single-wall carbon nanotubes or activated charcoal are previously shown to possess multiple nanozymatic activities including mimicking superoxide dismutase and catalyzing the oxidation of reduced nicotinamide adenine dinucleotide (NADH) to NAD+. These actions are predicted to generate a glycolytic shift and enhance mitochondrial energetics under impaired conditions. Impaired mitochondrial energy metabolism is increasingly recognized as an important facet of traumatic brain injury (TBI) pathophysiology and decreases the efficiency of electron transport chain (ETC)-coupled adenosine triphosphate (ATP) and NAD+ regeneration. In vitro, OCNs promote a …

Sex Differences In Response To Diet Enriched With Glutathione Precursors In The Aging Heart, Aude Angelini, Grecia Garcia Marquez, Anna Malovannaya, Marta L Fiorotto, Alexander Saltzman, Antrix Jain, Joann Trial, George E Taffet, Katarzyna A Cieslik

Faculty, Staff and Students Publications

Common features of the aging heart are dysregulated metabolism, inflammation, and fibrosis. Elevated oxidative stress is another hallmark of cardiac aging that can exacerbate each of these conditions. We hypothesize that by increasing natural antioxidant levels (glutathione), we will improve cardiac function. Twenty-one-month-old mice were fed glycine and N-acetyl cysteine (GlyNAC; glutathione precursors)-supplemented or control diets for 12 weeks. Heart function was monitored longitudinally, and the exercise performance was determined at the end of the study. We found that the GlyNAC diet was beneficial for old male but not old female mice, leading to an increase of Ndufb8 expression (a …

Mammalian Mitochondrial Inorganic Polyphosphate (Polyp) And Cell Signaling: Crosstalk Between Polyp And The Activity Of Ampk, Renata T. Da Costa, Anna Nichenko, Matheus M. Perez, Malgorzata Tokarska-Schlattner, Sheida Kavehmoghaddam, Vedangi Hambardikar, Ernest R. Scoma, Erin L. Seifert, Uwe Schlattner, Joshua C. Drake, Maria E. Solesio

Department of Pathology, Anatomy, and Cell Biology Faculty Papers

UNLABELLED: Inorganic polyphosphate (polyP) is an evolutionary and ancient polymer composed by orthophosphate units linked by phosphoanhydride bonds. In mammalian cells, polyP shows a high localization in mammalian mitochondria, and its regulatory role in various aspects of bioenergetics has already been demonstrated, via molecular mechanism(s) yet to be fully elucidated. In recent years, a role for polyP in signal transduction, from brain physiology to the bloodstream, has also emerged.

OBJECTIVE: In this manuscript, we explored the intriguing possibility that the effects of polyP on signal transduction could be mechanistically linked to those exerted on bioenergetics.

METHODS: To conduct our studies, …

Mechanistic Insights Into Metabolic Function Of Dynamin-Related Protein 1, Xin Li, Katherine Pham, Jazmin Ysaguirre, Iqbal Mahmud, Lin Tan, Bo Wei, Long J Shao, Maryam Elizondo, Rabie Habib, Fathima Elizondo, Hiromi Sesaki, Philip L Lorenzi, Kai Sun

Faculty, Staff and Student Publications

Dynamin-related protein 1 (DRP1) plays crucial roles in mitochondrial and peroxisome fission. However, the mechanisms underlying the functional regulation of DRP1 in adipose tissue during obesity remain unclear. To elucidate the metabolic and pathological significance of diminished DRP1 in obese adipose tissue, we utilized adipose tissue-specific DRP1 KO mice challenged with a high-fat diet. We observed significant metabolic dysregulations in the KO mice. Mechanistically, DRP1 exerts multifaceted functions in mitochondrial dynamics and endoplasmic reticulum (ER)-lipid droplet crosstalk in normal mice. Loss of function of DRP1 resulted in abnormally giant mitochondrial shapes, distorted mitochondrial membrane structure, and disrupted cristae architecture. Meanwhile, …

Junctophilin-2 Regulates Mitochondrial Metabolism, Sasha Z Prisco, Lynn M Hartweck, Felipe Kazmirczak, Jenna B Mendelson, Stephanie L Deng, Madelyn Blake, Satadru K Lahiri, Xander H T Wehrens, Kurt W Prins

Faculty, Staff and Students Publications

No abstract provided.

Deletion Of Mipep In Adipocytes Protects Against Obesity And Insulin Resistance By Boosting Muscle Metabolism, Alexis Diaz-Vegas, Kristen C Cooke, Harry B Cutler, Belinda Yau, Stewart W C Masson, Dylan Harney, Oliver K Fuller, Meg Potter, Søren Madsen, Niamh R Craw, Yiju Zhang, Cesar L Moreno, Melkam A Kebede, G Gregory Neely, Jacqueline Stöckli, James G Burchfield, David E James

Faculty, Staff and Students Publications

Mitochondria facilitate thousands of biochemical reactions, covering a broad spectrum of anabolic and catabolic processes. Here we demonstrate that the adipocyte mitochondrial proteome is markedly altered across multiple models of insulin resistance and reveal a consistent decrease in the level of the mitochondrial processing peptidase miPEP.

OBJECTIVE: To determine the role of miPEP in insulin resistance.

METHODS: To experimentally test this observation, we generated adipocyte-specific miPEP knockout mice to interrogate its role in the aetiology of insulin resistance.

RESULTS: We observed a strong phenotype characterised by enhanced insulin sensitivity and reduced adiposity, despite normal food intake and physical activity. Strikingly, …

Protocol For Seahorse Analysis Of Ex Vivo Mouse Brown And White Adipose Tissues, Fenfen Wang, Phu M Huynh, Yu A An

Faculty, Staff and Student Publications

The mitochondrial stress test is a gold-standard approach for assessing adipose tissue physiological functions and pathological changes. Here, we present a protocol for conducting Seahorse assays using ex vivo mouse brown and white adipose depots. We describe steps for rehydrating the cartridge, preparing freshly harvested fat depots, placing them onto an islet capture plate, and incubating them in a non-CO2 incubator. We then detail procedures for adding mitochondrial stressor solutions and conducting the mitochondrial stress test using the Seahorse XFe24 Analyzer. For complete details on the use and execution of this protocol, please refer to An et al.1.

Mitochondria Regulate Proliferation In Adult Cardiac Myocytes, Gregory B Waypa, Kimberly A Smith, Paul T Mungai, Vincent J Dudley, Kathryn A Helmin, Benjamin D Singer, Clara Bien Peek, Joseph Bass, Lauren Nelson, Sanjiv J Shah, Gaston Ofman, J Andrew Wasserstrom, William A Muller, Alexander V Misharin, G R Scott Budinger, Hiam Abdala-Valencia, Navdeep S Chandel, Danijela Dokic, Elizabeth Bartom, Shuang Zhang, Yuki Tatekoshi, Amir Mahmoodzadeh, Hossein Ardehali, Edward B Thorp, Paul T Schumacker

Faculty, Staff and Student Publications

Newborn mammalian cardiomyocytes quickly transition from a fetal to an adult phenotype that utilizes mitochondrial oxidative phosphorylation but loses mitotic capacity. We tested whether forced reversal of adult cardiomyocytes back to a fetal glycolytic phenotype would restore proliferative capacity. We deleted Uqcrfs1 (mitochondrial Rieske iron-sulfur protein, RISP) in hearts of adult mice. As RISP protein decreased, heart mitochondrial function declined, and glucose utilization increased. Simultaneously, the hearts underwent hyperplastic remodeling during which cardiomyocyte number doubled without cellular hypertrophy. Cellular energy supply was preserved, AMPK activation was absent, and mTOR activation was evident. In ischemic hearts with RISP deletion, new cardiomyocytes …

The Fatigue-Inducing Effects Of Cancer And Its Therapy Are Characterized By Decreased Physical Activity In The Absence Of Any Motivational Deficit, Thien T Phan, Kiersten S Scott, Brandon Chelette, A Phillip West, Robert Dantzer

Faculty, Staff and Student Publications

Although cancer and its therapy are well known to be associated with fatigue, the exact nature of cancer-related fatigue remains ill-defined. We previously reported that fatigue-like behavior induced independently by tumor growth and by the chemotherapeutic agent cisplatin is characterized by reduced voluntary wheel running and an intact motivation to expand effort for food rewards. The present set of experiments was initiated to characterize the functional consequences of fatigue induced by chemoradiotherapy in tumor-bearing mice and relate them to changes in the expression of genes coding for inflammation, mitochondria dynamics and metabolism. Two syngeneic murine models of cancer were selected …

Gpr84-Mediated Signal Transduction Affects Metabolic Function By Promoting Brown Adipocyte Activity, Xue-Nan Sun, Yu A An, Vivian A Paschoal, Camila O De Souza, May-Yun Wang, Lavanya Vishvanath, Lorena Ma Bueno, Ayanna S Cobb, Joseph A Nieto Carrion, Madison E Ibe, Chao Li, Harrison A Kidd, Shiuhwei Chen, Wenhong Li, Rana K Gupta, Da Young Oh

Faculty, Staff and Student Publications

The G protein-coupled receptor 84 (GPR84), a medium-chain fatty acid receptor, has garnered attention because of its potential involvement in a range of metabolic conditions. However, the precise mechanisms underlying this effect remain elusive. Our study has shed light on the pivotal role of GPR84, revealing its robust expression and functional significance within brown adipose tissue (BAT). Mice lacking GPR84 exhibited increased lipid accumulation in BAT, rendering them more susceptible to cold exposure and displaying reduced BAT activity compared with their WT counterparts. Our in vitro experiments with primary brown adipocytes from GPR84-KO mice revealed diminished expression of thermogenic genes …

Expert Panel Curation Of 113 Primary Mitochondrial Disease Genes For The Leigh Syndrome Spectrum, Elizabeth M Mccormick, Kierstin Keller, Julie P Taylor, Alison J Coffey, Lishuang Shen, Danuta Krotoski, Brian Harding, Xiaowu Gai, Marni J Falk, Zarazuela Zolkipli-Cunningham, Shamima Rahman

Children’s Nutrition Research Center Staff Publications

Objective: Primary mitochondrial diseases (PMDs) are heterogeneous disorders caused by inherited mitochondrial dysfunction. Classically defined neuropathologically as subacute necrotizing encephalomyelopathy, Leigh syndrome spectrum (LSS) is the most frequent manifestation of PMD in children, but may also present in adults. A major challenge for accurate diagnosis of LSS in the genomic medicine era is establishing gene-disease relationships (GDRs) for this syndrome with >100 monogenic causes across both nuclear and mitochondrial genomes.

Methods: The Clinical Genome Resource (ClinGen) Mitochondrial Disease Gene Curation Expert Panel (GCEP), comprising 40 international PMD experts, met monthly for 4 years to review GDRs for LSS. The GCEP …

The Transcription Factor Chrebp Links Mitochondrial Lipidomes To Mitochondrial Morphology And Progression Of Diabetic Kidney Disease, Li Li, Jianyin Long, Koki Mise, Naravat Poungavrin, Philip L Lorenzi, Iqbal Mahmud, Lin Tan, Pradip K Saha, Yashpal S Kanwar, Benny H Chang, Farhad R Danesh

Faculty, Staff and Students Publications

A substantial body of evidence has established the contributions of both mitochondrial dynamics and lipid metabolism to the pathogenesis of diabetic kidney disease (DKD). However, the precise interplay between these two key metabolic regulators of DKD is not fully understood. Here, we uncover a link between mitochondrial dynamics and lipid metabolism by investigating the role of carbohydrate-response element-binding protein (ChREBP), a glucose-responsive transcription factor and a master regulator of lipogenesis, in kidney podocytes. We find that inducible podocyte-specific knockdown of ChREBP in diabetic db/db mice improves key biochemical and histological features of DKD in addition to significantly reducing mitochondrial fragmentation. …

Ether Phospholipids Are Required For Mitochondrial Reactive Oxygen Species Homeostasis, Ziheng Chen, I-Lin Ho, Melinda Soeung, Er-Yen Yen, Jintan Liu, Liang Yan, Johnathon L Rose, Sanjana Srinivasan, Shan Jiang, Q Edward Chang, Ningping Feng, Jason P Gay, Qi Wang, Jing Wang, Philip L Lorenzi, Lucas J Veillon, Bo Wei, John N Weinstein, Angela K Deem, Sisi Gao, Giannicola Genovese, Andrea Viale, Wantong Yao, Costas A Lyssiotis, Joseph R Marszalek, Giulio F Draetta, Haoqiang Ying

Faculty, Staff and Student Publications

Mitochondria are hubs where bioenergetics, redox homeostasis, and anabolic metabolism pathways integrate through a tightly coordinated flux of metabolites. The contributions of mitochondrial metabolism to tumor growth and therapy resistance are evident, but drugs targeting mitochondrial metabolism have repeatedly failed in the clinic. Our study in pancreatic ductal adenocarcinoma (PDAC) finds that cellular and mitochondrial lipid composition influence cancer cell sensitivity to pharmacological inhibition of electron transport chain complex I. Profiling of patient-derived PDAC models revealed that monounsaturated fatty acids (MUFAs) and MUFA-linked ether phospholipids play a critical role in maintaining ROS homeostasis. We show that ether phospholipids support mitochondrial …

Supplementing Glycine And N-Acetylcysteine (Glynac) In Older Adults Improves Glutathione Deficiency, Oxidative Stress, Mitochondrial Dysfunction, Inflammation, Physical Function, And Aging Hallmarks: A Randomized Clinical Trial, Premranjan Kumar, Chun Liu, James Suliburk, Jean W Hsu, Raja Muthupillai, Farook Jahoor, Charles G Minard, George E Taffet, Rajagopal V Sekhar

Faculty, Staff and Students Publications

BACKGROUND: Elevated oxidative stress (OxS), mitochondrial dysfunction, and hallmarks of aging are identified as key contributors to aging, but improving/reversing these defects in older adults (OA) is challenging. In prior studies, we identified that deficiency of the intracellular antioxidant glutathione (GSH) could play a role and reported that supplementing GlyNAC (combination of glycine and N-acetylcysteine [NAC]) in aged mice improved GSH deficiency, OxS, mitochondrial fatty-acid oxidation (MFO), and insulin resistance (IR). To test whether GlyNAC supplementation in OA could improve GSH deficiency, OxS, mitochondrial dysfunction, IR, physical function, and aging hallmarks, we conducted a placebo-controlled randomized clinical trial.

METHODS: Twenty-four …

Supplementing Glycine And N-Acetylcysteine (Glynac) In Older Adults Improves Glutathione Deficiency, Oxidative Stress, Mitochondrial Dysfunction, Inflammation, Physical Function, And Aging Hallmarks: A Randomized Clinical Trial, Premranjan Kumar, Chun Liu, James Suliburk, Jean W Hsu, Raja Muthupillai, Farook Jahoor, Charles G Minard, George E Taffet, Rajagopal V Sekhar

Faculty, Staff and Students Publications

BACKGROUND: Elevated oxidative stress (OxS), mitochondrial dysfunction, and hallmarks of aging are identified as key contributors to aging, but improving/reversing these defects in older adults (OA) is challenging. In prior studies, we identified that deficiency of the intracellular antioxidant glutathione (GSH) could play a role and reported that supplementing GlyNAC (combination of glycine and N-acetylcysteine [NAC]) in aged mice improved GSH deficiency, OxS, mitochondrial fatty-acid oxidation (MFO), and insulin resistance (IR). To test whether GlyNAC supplementation in OA could improve GSH deficiency, OxS, mitochondrial dysfunction, IR, physical function, and aging hallmarks, we conducted a placebo-controlled randomized clinical trial.

METHODS: Twenty-four …

An Overview: The Diversified Role Of Mitochondria In Cancer Metabolism, Yu'e Liu, Yihong Sun, Yadong Guo, Xiaoyun Shi, Xi Chen, Wenfeng Feng, Lei-Lei Wu, Jin Zhang, Shibo Yu, Yi Wang, Yufeng Shi

Faculty, Staff and Students Publications

Mitochondria are intracellular organelles involved in energy production, cell metabolism and cell signaling. They are essential not only in the process of ATP synthesis, lipid metabolism and nucleic acid metabolism, but also in tumor development and metastasis. Mutations in mtDNA are commonly found in cancer cells to promote the rewiring of bioenergetics and biosynthesis, various metabolites especially oncometabolites in mitochondria regulate tumor metabolism and progression. And mutation of enzymes in the TCA cycle leads to the unusual accumulation of certain metabolites and oncometabolites. Mitochondria have been demonstrated as the target for cancer treatment. Cancer cells rely on two main energy …

Chronic Restraint Stress Impairs Voluntary Wheel Running But Has No Effect On Food-Motivated Behavior In Mice, Kiersten Scott, Thien Trong Phan, Nabila Boukelmoune, Cobi J Heijnen, Robert Dantzer

Faculty, Staff and Student Publications

Chronic restraint stress is known to cause significant alterations of mitochondrial biology. However, its effects on effort-based behavior and the sensitivity of these effects to treatments that restore mitochondrial function have not been assessed. Based on the hypothesis that the behavioral consequences of this stressor should be more severe for an energy demanding activity than for an energy procuring activity, we compared the effects of chronic restraint stress on the performance of male mice trained to use a running wheel or to nose poke for a food reward in an operant conditioning cage. In accordance with our hypothesis, we observed …

The Use Of Second-Generation Antipsychotics And The Changes In Physical Growth In Children And Adolescents With Perinatally Acquired Hiv, Nan Xin, Jenni Durieux, Chunxia Yang, Suzanne Wolff, Hyun-Eui Kim, Andrew Dillin

Faculty, Staff and Student Publications

The mitochondrial unfolded protein response (UPRmt) is dedicated to promoting mitochondrial proteostasis and is linked to extreme longevity. The key regulator of this process is the transcription factor ATFS-1, which, upon UPRmt activation, is excluded from the mitochondria and enters the nucleus to regulate UPRmt genes. However, the repair proteins synthesized as a direct result of UPRmt activation must be transported into damaged mitochondria that had previously excluded ATFS-1 owing to reduced import efficiency. To address this conundrum, we analyzed the role of the import machinery when the UPRmt was induced. Using in vitro and in vivo analysis of mitochondrial …

A Cancer Ubiquitome Landscape Identifies Metabolic Reprogramming As Target Of Parkin Tumor Suppression, Ekta Agarwal, Aaron R Goldman, Hsin-Yao Tang, Andrew V Kossenkov, Jagadish C Ghosh, Lucia Languino, Valentina Vaira, David W Speicher, Dario C Altieri

Department of Cancer Biology Faculty Papers

Changes in metabolism that affect mitochondrial and glycolytic networks are hallmarks of cancer, but their impact in disease is still elusive. Using global proteomics and ubiquitome screens, we now show that Parkin, an E3 ubiquitin ligase and key effector of mitophagy altered in Parkinson's disease, shuts off mitochondrial dynamics and inhibits the non-oxidative phase of the pentose phosphate pathway. This blocks tumor cell movements, creates metabolic and oxidative stress, and inhibits primary and metastatic tumor growth. Uniformly down-regulated in cancer patients, Parkin tumor suppression requires its E3 ligase function, is reversed by antioxidants, and is independent of mitophagy. These data …

Sirt3 Is Required For Liver Regeneration But Not For The Beneficial Effect Of Nicotinamide Riboside, Sarmistha Mukherjee, James Mo, Lauren M Paolella, Caroline E Perry, Jade Toth, Mindy M Hugo, Qingwei Chu, Qiang Tong, Karthikeyani Chellappa, Joseph A Baur

Children’s Nutrition Research Center Staff Publications

Liver regeneration is critical to survival after traumatic injuries, exposure to hepatotoxins, or surgical interventions, yet the underlying signaling and metabolic pathways remain unclear. In this study, we show that hepatocyte-specific loss of the mitochondrial deacetylase SIRT3 drastically impairs regeneration and worsens mitochondrial function after partial hepatectomy. Sirtuins, including SIRT3, require NAD as a cosubstrate. We previously showed that the NAD precursor nicotinamide riboside (NR) promotes liver regeneration, but whether this involves sirtuins has not been tested. Here, we show that despite their NAD dependence and critical roles in regeneration, neither SIRT3 nor its nuclear counterpart SIRT1 is required for …

Enhancing Glucose Metabolism Via Gluconeogenesis Is Therapeutic In A Zebrafish Model Of Dravet Syndrome, Rajeswari Banerji, Christopher Huynh, Francisco Figueroa, Matthew T Dinday, Scott C Baraban, Manisha Patel

Faculty, Staff and Students Publications

Energy-producing pathways are novel therapeutic targets for the treatment of neurodevelopmental disorders. Here, we focussed on correcting metabolic defects in a catastrophic paediatric epilepsy, Dravet syndrome which is caused by mutations in sodium channel NaV1.1 gene, SCN1A. We utilized a translatable zebrafish model of Dravet syndrome (scn1lab) which exhibits key characteristics of patients with Dravet syndrome and shows metabolic deficits accompanied by down-regulation of gluconeogenesis genes, pck1 and pck2. Using a metabolism-based small library screen, we identified compounds that increased gluconeogenesis via up-regulation of pck1 gene expression in scn1lab larvae. Treatment with PK11195, a pck1 activator …

Mir-30a Targets Gene Networks That Promote Browning Of Human And Mouse Adipocytes, Pradip K Saha, Mark P Hamilton, Kimal Rajapakshe, Vasanta Putluri, Jessica B Felix, Peter Masschelin, Aaron R Cox, Mandeep Bajaj, Nagireddy Putluri, Cristian Coarfa, Sean M Hartig

Faculty, Staff and Students Publications

MicroRNA-30a (miR-30a) impacts adipocyte function, and its expression in white adipose tissue (WAT) correlates with insulin sensitivity in obesity. Bioinformatic analysis demonstrates that miR-30a expression contributes to 2% of all miRNA expression in human tissues. However, molecular mechanisms of miR-30a function in fat cells remain unclear. Here, we expanded our understanding of how miR-30a expression contributes to antidiabetic peroxisome proliferator-activated receptor-γ (PPARγ) agonist activity and metabolic functions in adipocytes. We found that WAT isolated from diabetic patients shows reduced miR-30a levels and diminished expression of the canonical PPARγ target genes ADIPOQ and FABP4 relative to lean counterparts. In human adipocytes, …

Methyl-Sensing Nuclear Receptor Liver Receptor Homolog-1 Regulates Mitochondrial Function In Mouse Hepatocytes, Sungwoo Choi, Bingning Dong, Chih-Chun Janet Lin, Mi Jeong Heo, Kang Ho Kim, Zhen Sun, Martin Wagner, Nagireddy Putluri, Jae Myoung Suh, Meng C Wang, David D Moore

Faculty, Staff and Students Publications

Liver receptor homologue-1 (LRH-1; NR5A2) is a nuclear receptor that regulates metabolic homeostasis in the liver. Previous studies identified phosphatidylcholines as potential endogenous agonist ligands for LRH-1. In the liver, distinct subsets of phosphatidylcholine species are generated by two different pathways: choline addition to phosphatidic acid via the Kennedy pathway, or trimethylation of phosphatidylethanolamine via Phosphatidylethanolamine N-methyl Transferase (PEMT). Here we report that a PEMT - LRH-1 pathway specifically couples methyl metabolism and mitochondrial activities in hepatocytes. We show that the loss of Lrh-1 reduces mitochondrial number, basal respiration, beta-oxidation and ATP production in hepatocytes, and decreases expression of mitochondrial …

Student-Faculty Collaborative Research Grant Report, Megan Bestwick

Post-Grant Reports

Mitochondria are essential organelles in most eukaryotic cells because of their role in metabolism and the production of ATP by the oxidative phosphorylation (OXPHOS) pathway, as well as other key cellular processes. Metal cofactors, such as copper (Cu) and iron (Fe), are incorporated into OXPHOS protein complexes of yeast located within the inner membrane of the mitochondria. Misincorporation or modulation of these available metals in mitochondrial enzymes leads to the production of reactive oxygen species (ROS). ROS are reactive molecules containing oxygen such as peroxides, superoxide, and hydroxyl radicals. Yeast are a good model for studying aging and the effect …

Mitochondrial Metabolism In Major Neurological Diseases, Zhengqiu Zhou, Grant L. Austin, Lyndsay E. A. Young, Lance A. Johnson, Ramon Sun

Molecular and Cellular Biochemistry Faculty Publications

Mitochondria are bilayer sub-cellular organelles that are an integral part of normal cellular physiology. They are responsible for producing the majority of a cell’s ATP, thus supplying energy for a variety of key cellular processes, especially in the brain. Although energy production is a key aspect of mitochondrial metabolism, its role extends far beyond energy production to cell signaling and epigenetic regulation–functions that contribute to cellular proliferation, differentiation, apoptosis, migration, and autophagy. Recent research on neurological disorders suggest a major metabolic component in disease pathophysiology, and mitochondria have been shown to be in the center of metabolic dysregulation and possibly …

Acute Loss Of Iron-Sulfur Clusters Results In Metabolic Reprogramming And Generation Of Lipid Droplets In Mammalian Cells, Daniel R. Crooks, Nunziata Maio, Andrew N. Lane, Michal Jarnik, Richard M. Higashi, Ronald G. Haller, Ye Yang, Teresa Whei-Mei Fan, W. Marston Linehan, Tracey A. Rouault

Center for Environmental and Systems Biochemistry Faculty Publications

Iron–sulfur (Fe-S) clusters are ancient cofactors in cells and participate in diverse biochemical functions, including electron transfer and enzymatic catalysis. Although cell lines derived from individuals carrying mutations in the Fe-S cluster biogenesis pathway or siRNA-mediated knockdown of the Fe-S assembly components provide excellent models for investigating Fe-S cluster formation in mammalian cells, these experimental strategies focus on the consequences of prolonged impairment of Fe-S assembly. Here, we constructed and expressed dominant–negative variants of the primary Fe-S biogenesis scaffold protein iron–sulfur cluster assembly enzyme 2 (ISCU2) in human HEK293 cells. This approach enabled us to study the early metabolic reprogramming …