Dr. Morgan Fullerton

Biography

Research Interests

The Fullerton laboratory is interested in understanding various aspects of metabolism, with a specific focus on lipid homeostasis in liver and innate immune cells. Many fundamental cellular processes are intimately linked to lipid metabolism, and our research aims to uncover some of the underlying mechanisms by which these processes are altered in chronic diseases such as insulin resistance (which leads to type 2 diabetes) and atherosclerosis (which leads to heart disease). We use genetically engineered (knock-out and knock-in) mice, that have targeted changes to specific metabolic pathways, in combination with molecular, biochemical and cellular biology techniques to investigate changes in whole-body physiology. Our aim is to better understand how these pathways function, in normal and diseased conditions, so to potentially develop novel strategies to prevent and treat chronic metabolic diseases.

AMPK regulation of macrophage cholesterol metabolism in atherosclerosis

Heart disease is a condition that affects more than one million Canadians, and costs the Canadian healthcare system almost 21 billion dollars annually. Atherosclerosis is the buildup of cholesterol and immune cells in the lining of the arteries (atherosclerotic plaque), and is a leading cause of heart attack and stroke. In addition to heart disease risk factors such as obesity and type 2 diabetes, the way that our body handles the build up of cholesterol in the arteries is also very important. Specialized immune cells called macrophages are able to take up and store excess cholesterol, protecting the artery wall in the process. These macrophages have specialized pathways to then transfer the cholesterol they scavenge to the circulating lipoprotein “HDL”, which then carries the cholesterol to the liver, where it can be safely removed (this is why HDL-cholesterol is called the “good” cholesterol). This is known as reverse cholesterol transport. However, when this process is overwhelmed, cholesterol builds in macrophages, turning them into foam cells and causing atherosclerosis to progress. The AMP-activated protein kinase (AMPK) is an important metabolic regulator that ensures there is enough cellular energy, and has been shown to play important roles in carbohydrate, protein and lipid metabolism. We have evidence to suggest that AMPK favourably alters lipid metabolism and are interested in determining the role of AMPK in macrophages and atherosclerosis. We use genetically engineered mice that are lacking the AMPK gene, as well as therapeutic compounds that specifically activate AMPK to test our hypotheses. The goal of our research is to investigate and uncover novel mechanisms that contribute to atherosclerosis and heart disease in the hopes of developing more effective prevention and therapeutic strategies.

CTL1 and the role of choline uptake in metabolic disease

Choline is an essential nutrient and a key molecular building block in mammals. A fundamental component of membrane phospholipids, choline is a precursor for the biosynthesis of the neurotransmitter acetylcholine, as well is an important donor of methyl groups for epigenetic regulation. Accordingly, choline deficiency can cause developmental impairments, decreased cognitive function, liver dysfunction, and abnormalities in lipid metabolism and gene regulation.  Choline is a positively charged molecule that requires transport to cross the lipid bilayer. Choline transporter-like protein-1 (CTL1) is a member of a new family of transporters and has been shown to be widely expressed and to transport choline at a high-affinity. The limited number of initial studies have used cell culture models to investigate the regulation and the associated choline transport of CTL1; however, there are no studies that have addressed the importance of CTL1 in a physiological animal model. Our research involves generating and characterizing a novel knockout mouse model, where the CTL1 gene (Slc44a1) will be targeted for disruption (CTL1 KO) and represents the necessary next step to fully understand the role of CTL1 in the transport and subsequent metabolism of choline in the body.

Publications

• Hunter RW, Foretz M, Bultot L, Fullerton MD, Deak M, Ross FA, Hawley SA, Shpiro N, Viollet B, Barron D, Kemp BE, Steinberg GR, Hardie DG, Sakamoto K. Mechanism of Action of Compound-13: An α1-Selective Small Molecule Activator of AMPK. Chem Biol. 2014 Jul 17;21(7):866-79.
• Henriksbo BD, Lau TC, Cavallari JF, Denou E, Fullerton MD, Tarnopolsky MA, Steinberg GR, Schertzer JD. Fluvastatin causes NLRP3 inflammasome-mediated adipose insulin resistance. Diabetes 2014 Jun 10. pii: DB_131398. [Epub ahead of print].
• O'Neill HM, Lally JS, Galic S, Thomas M, Azizi PD, Fullerton MD, Smith BK, Pulinilkunnil T, Chen Z, Samaan MC, Jorgensen SB, Dyck JR, Holloway GP, Hawke TJ, van Denderen BJ, Kemp BE, Steinberg GR. AMPK phosphorylation of ACC2 is required for skeletal muscle fatty acid oxidation and insulin sensitivity in mice. Diabetologia. 2014 Aug;57(8):1693-702.
• Bujak A, Blümer RM, Marcinko K, Fullerton MD, Kemp BE, Steinberg GR. Reduced skeletal muscle AMPK and mitochondrial content does not promote the development of aging-induced insulin resistance.  J Appl Physiol (1985). 2014 Jul 15;117(2):171-9.
• Bojic LA, Telford DE, Fullerton MD, Ford RJ, Sutherland BJ, Edwards JY, Sawyez CG, Gros R, Steinberg GR, and Huff MW. PPARδ-specific activation in liver attenuates triglyceride accumulation via enhanced fatty acid oxidation, reduced fatty acid synthesis and improved insulin sensitivity. J Lipid Res. 2014 May 26;55(7):1254-1266.
• Samaan MC, Marcinko K, Sikkema S, Fullerton MD, Ziafazeli T, Khan MI, Steinberg GR. Endurance interval training in obese mice reduces muscle inflammation and macrophage content independently of weight loss. Physiol Rep. 2014 May 19;2(5). pii: e12012. doi: 10.14814/phy2.12012.
• Fullerton MD and Steinberg GR. ‘Presenting’ an adaptive role for AMPK. J Leukoc Biol. 2013 Dec;94(6):1099-101. 
• Fullerton MD*, Galic S*, Marcinko K, Sikkema S, Pulinilkunnil T, O'Neill HM, Ford RJ, Palanivel R, O’Brien M, Hardie DG, Macaulay SL, Schertzer JD, Dyck JR, Kemp BE, Steinberg GR. A single amino acid in Acc1 and Acc2 regulates lipid homeostasis and the insulin-sensitizing effects of metformin. Nature Medicine, 2013 Dec;19(12):1649-54.
• Fullerton MD, Steinberg GR, Schertzer JD. Immunometabolism of AMPK in insulin resistance and atherosclerosis. Mol Cell Endocrinol. 2012, Feb 25;366(2):224-34
• Shulga YV, Loukov D, Ivanova PT, Milne SB, Myers DS, Hatch GM, Umeh G, Jalan D, Fullerton MD, Steinberg GR, Topham MK, Brown HA, Epand RM. Diacylglycerol Kinase Delta Promotes Lipogenesis. Biochemistry. 2013 Nov 5;52(44):7766-76
• Jorgensen SB, O'Neill HM, Sylow L, Honeyman J, Hewitt KA, Palanivel R, Fullerton MD, Öberg L, Balendran A, Galic S, van der Poel C, Trounce IA, Lynch GS, Schertzer JD, Steinberg GR. Deletion of Skeletal Muscle SOCS3 Prevents Insulin Resistance in Obesity. Diabetes. 2013 Jan;62(1):56-64.
• Basseri S, Lhoták S, Fullerton MD, Palanivel R, Jiang H, Lynn EG, Ford RJ, Maclean KN, Steinberg GR, Austin RC. Loss of TDAG51 results in mature-onset obesity, hepatic steatosis, and insulin resistance by regulating adipogenesis and lipogenesis. Diabetes. 2013 Jan;62(1):158-69.
• Palanivel R, Fullerton MD, Galic S, Honeyman J, Hewitt KA, Jorgensen SB, Steinberg GR. Reduced Socs3 expression in adipose tissue protects female mice against obesity-induced insulin resistance. Diabetologia. 2012 Nov;55(11):3083-93.
• Singh RK, Fullerton MD, Vine D, Bakovic M. Mechanisms of hypertriglyceridemia in CTP:phosphoethanolamine cytidylyltransferase (Pcyt2) deficient mice. J Lipid Res. 2012 Sept;53(9):1811-22. Citations: 2
• Hawley SA, Fullerton MD, Ross FA, Schertzer JD, Chevtzoff C, Walker KJ, Peggie MW, Zibrova D, Green KA, Mustard KJ, Kemp BE, Sakamoto K, Steinberg GR and Hardie DG. The ancient drug salicylate directly activates AMP-activated protein kinase. Science. 2012 May 18;336(6083):918-22.
• Fullerton MD*, Galic S*, Schertzer JD, Sikkema S, Marcinko K, Walkley CR, Izon D, Honeyman J, Chen ZP, van Denderen BJ, Kemp BE, Steinberg GR. Hematopoietic deletion of AMPK β1 exacerbates inflammation and hepatic insulin resistance in obesity. J Clin Invest. 2011 Dec;121(12):4903-15.
• Schertzer JD, Tamrakar AK, Magalhães JG, Pereira S, Bilan PJ, Fullerton MD, Philpott DJ, Steinberg GR, Giacca A and Klip A. NOD1 activators link innate immunity and insulin resistance. Diabetes. 2011, Sep;60(9):2206-15.
• Fullerton MD, Steinberg GR. SirT1 takes a back seat to AMPK in the regulation of insulin sensitivity by resveratrol. Diabetes 2010 Mar;59(3):551-3.
• Fullerton MD, Bakovic M. Complementation of the metabolic defect in CTP: phosphoethanolamine cytidylyltransferase (Pcyt2) deficient primary hepatocytes. Metabolism 2010 Dec;59(12):1691-700.
• Fullerton MD, Hakimuddin F, Bonen A, Bakovic M. The Development of a Metabolic Disease Phenotype in CTP:Phosphoethanolamine Cytidylyltransferase-deficient Mice. J Biol Chem. 2009 Sep 18; 284(38):25704-13. Epub 2009 Jul 22.
• Wood KC, Fullerton MD, El-Sohemy A, Bakovic M. Interactions between hepatic lipase and apolipoprotein E gene polymorphisms affect serum lipid profiles of healthy Canadian adults. Appl Physiol Nutr Metab. 2008 Aug; 33(4): 761-8.
• Fullerton MD, Hakimuddin F, Bakovic M. Developmental and metabolic effects of disruption of the mouse CTP:phosphoethanolamine cytidylyltransferase gene (Pcyt2). Mol Cell Biol. 2007 May; 27(9): 3327-36.
• Bakovic M, Fullerton MD, Michel V. Metabolic and molecular aspects of ethanolamine phospholipid biosynthesis: the role of CTP:phosphoethanolamine cytidylyltransferase (Pcyt2). Biochem Cell Biol. 2007 Jun; 85(3): 283-300. Invited Review.
• Fullerton MD, Wagner L, Yuan Z, Bakovic M. Impaired trafficking of choline transporter-like protein-1 at plasma membrane and inhibition of choline transport in THP-1 monocyte-derived macrophages. Am J Physiol Cell Physiol. 2006 Apr; 290 (4): C1230-8.