Michel Pelletier

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Michel Pelletier , Ph.D

(He/Him/His)

Associate Professor and Chair (Biology)

(585) 395-5765
mpelleti@brockport.edu
Office: Lennon Hall B19

Bio

The major focus of my research is to characterize and better understand lipid biosynthesis in the parasite Trypanosoma brucei, the causative agent of African sleeping sickness in human, using a dual genetic/biochemical approach. Due to the importance of lipid biosynthesis in trypanosome, it is very likely that enzymes involved in these biosynthetic pathways play an essential role and could be used as a drug target. Specifically, we are interested in determining how post-translational modifications such as phosphorylation and arginine methylation regulate the activity of TbLpn, a protein likely to be involved in phospholipid biosynthesis in T. brucei.

Education

Ph.D. Microbiology: Department of Biochemistry

Université Laval, Quebec city, Canada

M.Sc. Microbiology: Department of Biochemistry

Université Laval, Quebec city, Canada

B.Sc. Microbiology: Department of Biochemistry

Université Laval, Quebec city, Canada

Areas of Specialty

Microbiology, Parasitology, Immunology

Courses Taught

BIO 323-Microbiology

BIO 414/514-Immunology

BIO 430-Immunology Lab

BIO 423/643-General Microbiology

BIO 433/533-Bacterial Physiology and Genetics

Research Interests

Human African Trypanosomiasis, also known as African sleeping sickness, is a vector-borne devastating disease caused by the parasitic protozoan Trypanosoma brucei. This parasite is transmitted between mammalian hosts by the tsetse flies of the genus Glossina. According to the World Health Organization (WHO), sleeping sickness threatens over 60 million people in 36 countries of sub-Saharan Africa. Over 70,000 deaths every year are a result of sleeping sickness and the disease is always fatal unless treated.1 During recent epidemics in several villages in the Democratic Republic of Congo, Angola, and Southern Sudan, the prevalence of the disease has reached 50%, and sleeping sickness was considered the first or second greatest cause of mortality, ahead of HIV/AIDS.1 T. brucei is also pathogenic to animals where it causes a disease known as nagana, particularly in African livestock. T. brucei is an evolutionarily ancient organism, further removed from yeast than yeast is from humans.2 The entire life cycle of T. brucei occurs extracellularly. After a mammalian host is inoculated by an infected tsetse fly, metacyclic trypomastigotes migrate from the skin tissue to the lymphatic system and pass into the bloodstream. Bloodstream form trypanosomes evade the host immune system by constantly changing the antigenic composition of the variant surface glycoprotein (VSG) coat. Inside the host, they transform into bloodstream trypomastigotes and move to the tissues and various organs. The tsetse fly becomes infected with bloodstream form trypomastigotes when taking a blood meal on an infected mammalian host. The then enter the fly midgut in which they transform into procyclic form trypomastigotes. In T. brucei, transcriptional gene regulation is essentially absent. Rather, gene expression is controlled primarily at the levels of RNA processing, stability, and translation, and likely involves a substantial number of RNA binding proteins.3-5 Besides its great health and economic importance, T. brucei represents an exceptional tool for the study of cell physiology/biology due to the possibility of carrying out RNA interference in this organism.

Protein arginine methylation is a post-translational modification resulting in the addition of methyl groups from S-adenosylmethionine (AdoMet) to the nitrogen of arginine residues in proteins.6-8 Arginine methylation is catalyzed by enzymes known as protein arginine methyltransferases (PRMTs). PRMTs have been identified in a variety of organisms including mammals, yeasts, plants, and protozoa.7, 9-11 Recent reports have established a role for arginine methylation in the control of signal transduction,12-14 RNA transport,15-16 RNA processing,17-19 protein localization,20-22 and transcription.23 However, the functional significance of many arginine methylation events is currently unknown. In mammalian cells, two major and distinct types of PRMTs have been identified. Type I enzymes catalyze the formation of both monomethylarginine (MMA) and asymmetrical dimethylarginine (ADMA), while the type II enzyme forms MMA and symmetrical dimethylarginine (SDMA). Interestingly, arginine methylation catalyzed by type I and type II often occurs within RGG, RG, or RXR motifs of RNA-binding proteins,6, 24, 25 suggesting that arginine methylation is likely to play a key role in the control of gene expression in T. brucei.

To understand the roles of arginine methylation in trypanosome gene expression, and to identify substrates and/or regulators of PRMTs in T. brucei, we began by identifying proteins interacting with the major type I PRMT, TbPRMT1, using a yeast-two-hybrid screening. This revealed several potential TbPRMT1 interacting proteins, notably a protein homologous to yeast and human lipin, a phosphatidate phosphatase involved in membrane biogenesis, energy metabolism, and adipose tissue development. The lipin family of proteins have dual cellular functions, acting as an enzyme required for triacylglycerol (TAG) and phospholipids biosynthesis, and as a transcriptional coactivator in the regulation of lipid metabolism genes (Figure 1).26 As phospholipids constitute the major constituents of biological membranes, lipin plays a pivotal role in membrane biogenesis. The first member of the family, lipin-1, was first identified through positional cloning of the mutant gene responsible for fatty liver dystrophy (fld), a genetic disease characterized by loss of body fat, fatty liver, hypertriglyceridemia, and insulin resistance.27 In mammals, 3 members of the lipin gene family have been identified. Two lipin-1 protein isoforms are generated by alternative mRNA splicing of the Lpin1 gene.28 Lipin-2 and Lipin-3 were identified through sequence similarity to lipin-1.27 While lipin-1 is mostly expressed in white and brown adipocytes, skeletal muscles, and testis,27 lipin-2 is mostly present in liver and brain, whereas lipin-3 is present in small intestine and liver, albeit at low levels.29 In mouse, two Lpin-1-related genes, Lpin2 and Lpin3, have also been identified. Orthologs have also been found in Saccharomyces cerevisiae, Schyzosaccharomyces pombe, Drosophila, Caenorhabditis elegans, Arabidopsis thaliana, and Plasmodium falciparum. Sequence alignments of the lipin-related genes revealed the presence of two highly conserved regions, designated amino-terminal and carboxy-terminal lipin (NLIP and CLIP) domains.

Two distinct functions of lipin-1 have recently been identified. First, lipin-1 acts as a Mg2+-dependent phosphatidate phosphatase (PAP1) involved in TAG and phospholipids biosynthesis. Lipin-1 catalyzes the dephosphorylation of phosphatidic acid (PA) to diacylglycerol (DAG) which, in turn, is used for the synthesis of phosphatidylcholine (PC) and phosphatidylethanolamine (PE), as well as TAG Figure 2). In eukaryotic cells, PC and PE are the most abundant phospholipids, usually accounting for 30-50% and 20-40%, respectively, of total phospholipids.30-31 In the presence of high levels of fatty acids within the cells, lipin translocates from the cytosol to the endoplasmic reticulum, where it converts phosphatidic acid to diacylglycerol. Lipin-1-deficient cells are immature adipocytes unable to store lipid or express mature adipocyte markers.32 This results in a loss of body weight, peripheral neuropathy due to myelin degradation, Schwann cell differentiation defects and proliferation, and nerve conduction velocity (Figure 3).33-35

The yeast ortholog of lipin, PAH1, was later identified in Saccharomyces cerevisiae, and was shown to possess the same Mg2+-dependent PAP1 activity. The catalytic activity was mapped to the DxDxT motif present in the CLIP domain of PAH1.36 and was later shown to be present in all lipin-related proteins. As for their mammalian counterparts, pah1Ģ mutants contain elevated levels of PA and low levels of DAG and TAG. The levels of phosphatidylinositol (PI), PC, and PE, are also affected in these mutants.36, 37. In addition, PAH1-deficient mutants exhibit aberrant expansion of the nuclear/ER membrane due to elevated PA levels and derepression of phospholipids synthesis genes, attributed to increased concentration of PA at the nuclear/ER membrane .37

The T. brucei lipin homologue was identified by yeast-two-hybrid as a TbPRMT1-interacting protein. The gene, located on chromosome VII (locus Tb927.7.5450), encodes a predicted 806 amino acid protein, which we termed TbLpn. The predicted protein has a molecular weight of 86.7 kDa and a pI of 4.9, and displays, at the amino acid level, between 15 and 25% identity to the lipin family of protein. Most importantly, the two conserved regions NLIP and CLIP, characteristic of the lipin family of protein, are also present in TbLpn (Figure 4). In addition, careful examination of the predicted amino acid sequence revealed the presence of the DxDxT motif, namely DVDGT, located from amino acid 445 to 449. This clearly suggests that TbLpn possesses PAP1 activity and represent a functional homologue of lipin proteins

As for other eukaryotes, PC and PE constitute the majority of phospholipids in trypanosomes.38 Of great importance is the fact that, as opposed to other parasitic organisms, trypanosomes synthesize phospholipids de novo. This makes the trypanosome phospholipids biosynthesis machinery a very attractive target for new drug design. Although the pathways for phospholipids biosynthesis have not been very well characterized, recent data have helped to better understand how trypanosomes are able to assemble phospholipids. For example, the steps involved in the biosynthesis of glycosylphosphatidylinositol (GPI), a process essential for T. brucei bloodstream form survival, have been well studied. This synthesis differs in certain aspects from the pathway in mammalian cells and yeast, making phospholipids synthesis even more important as a drug target. Furthermore, the pathways for the synthesis of PI and PE have recently been determined.39, 40 We recently carried out down-regulation of TbLpn expression in procyclic form T. brucei by RNA interference, and found that TbLpn is essential for cell growth (Figure 5).

The major focus ofmy research is to identify the function(s) of Tblpn and its importance in trypanosome metabolism and infectivity using a dual genetic/biochemical approach. Functions of Tblpn in vivo will be assessed by disrupting its expression by RNA interference and determining the effect of the disruption on cellular growth, cellular phospholipid content, phosphatidic acid phosphatase activity, cell morphology, and expression of lipid biosynthetic genes, just to name a few.

• Awards/Recognitions
  • Chancellor’s Award for Excellence in Teaching
  • Presidential Teaching Excellence Award
• Recent Publications
  • Pelletier, M., and Draper, J. (2022). Characterization and identification of bacterial flora from infected equine hooves. International Journal of Veterinary Science and Research. April 27, 2022: 50-56.
  • Pelletier, M., Haynes, J. M., Dungan, A. M., Kroeckel, J. (2014). Characterization of the microbial population found in and around San Salvador Island, Bahamas. The International Journal of Bahamian Studies. 20:27-37.
  • Pelletier, M., Frainier, A. S., Munini, D. N., Wiemer, J. M., Karpie, A. R., Sattora, J. J. (2013). Identification of a novel lipin homologue from the parasitic protozoan Trypanosoma brucei. BMC Microbiology, 13(101), 11. www.biomedcentral.com/1471-2180/13/101.
  • Pelletier, M., Read, L.K., and Aphasizhev, R. (2007). Purification of RNA editing accessory factors from Trypanosoma brucei. Methods in Enzymology Vol 424:75-105.
  • Duan, P., Xu, Y., Birkaya, B., Myers, J., Pelletier, M., Read, LK., Guarnaccia, C., Pongor, S., Denman, RB., and Aletta, J.M. (2007). Generation of polyclonal antiserum for the detection of methylarginine proteins. Journal of Immunological Methods 320:132-142.
  • Goulah, C., Pelletier, M., and Read L.K. (2006). Arginine methylation regulates mitochondrial gene expression in Trypanosoma brucei through multiple effector proteins. RNA 12:1545-1555.
  • Pelletier, M., Pasternack, D.A., and Read, L.K. (2005). In vitro and in vivo analysis of the major type I protein arginine methyltransferase from Trypanosoma brucei. Molecular and Biochemical Parasitology 144:206-217.
  • Pelletier, M., and Read, L.K. (2003). RBP16 is a multifunctional gene regulatory protein involved in editing and stabilization of specific mitochondrial mRNAs in Trypanosoma brucei. RNA 9(4):457-68.
  • Pelletier, M., Xu, Y., Wang, X., Zahariev, S., Pongor, S., Aletta, J.M., and Read, L.K. (2001). Arginine methylation of a mitochondrial guide RNA binding protein from Trypanosoma brucei. Molecular and Biochemical Parasitology 118:49-59.
  • Pelletier, M., Miller, M.M., and Read, L.K. (2000). RNA-binding properties of the mitochondrial Y-box protein RBP16. Nucleic Acids Research 28: 1266-1275.
• Presentations
  • Hoyser, J., Drum, M., Pelletier, M. Arginine Methylation of TbLpn in Trypanosoma brucei and its Roles in Phosphatidic Acid Phosphatase Enzymatic Activity. Scholars Day 2022, SUNY Brockport, Brockport, NY. (April 13, 2022).
  • Aloyce, A., Pelletier, M. Prevention and Control of Tropical Diseases in The Democratic Republic of Congo. Scholars Day 2022, SUNY Brockport, Brockport, NY. (April 13, 2022).
  • Wasson, E., Pelletier, M. STOP Study: Sanitize to Omit Pathogens. Scholars Day 2022, SUNY Brockport, Brockport, NY. (April 13, 2022).
  • VanGelder, A., Pelletier, M. The Effect of Phosphorylation on the Enzymatic Activity of TbLpn, a Trypanosoma brucei Phosphatidic Acid Phosphatase. Scholars Day 2022, SUNY Brockport, Brockport, NY. (April 13, 2022).
  • Hoyser, J., Pelletier, M. Arginine Methylation of TbLpn in Trypanosoma brucei and its Roles in Phosphatidic Acid Phosphatase Enzymatic Activity. Rochester Academy of Science, Rochester, NY, United States. (November 6, 2021).
  • Drum, M., Pelletier, M. Effect of Arginine Methylation on the Enzymatic Activity of TbLpn and its Role in Phospholipid Biosynthesis in Trypanosoma brucei,” Rochester Academy of Science, Rochester, NY, United States. (November 6, 2021).
  • Case, Z., VanGelder, A., Pelletier, M. Effect of Phosphorylation on the Enzymatic Activity of TbLpn, a Trypanosoma brucei Phosphatidic Acid Phosphatase. Rochester Academy of Science, Rochester, NY, United States. (November 6, 2021).
  • Baron, C., Pelletier, M. TbLpn and the Effect of Phosphorylation on Enzymatic PAP Activity, Scholars Day 2021, SUNY Brockport, Brockport, NY, (April 2021).
  • Mousso, T., and Pelletier M. Determination of the Roles of Trypanosoma brucei Lipin Homologue TbLpn. Scholars Day 2020, SUNY Brockport, Brockport, NY., (April 2020).
  • Case, Z., and Pelletier, M. Effect of Arginine Methylation on the Enzymatic Activity and Functions of TbLpn in Trypanosoma brucei. Scholars Day 2020, SUNY Brockport, Brockport, NY., (April 2020).
  • Green, E., and Pelletier, M., Phospholipid Biosynthesis and Arginine Methylation in Trypanosoma brucei. Scholars Day 2020, SUNY Brockport, Brockport, NY., (April 2020).
  • Seaburg, J., Schultz, T., and Pelletier, M. Effect of Dietary Magnesium on the Microbiome of the Spleen in a Mouse Model of Ulcerative Colitis. Scholars Day 2019, SUNY Brockport, Brockport, NY., (April 10, 2019).
  • Raichel, A., and Pelletier, M. Investigation of TbLpn methylation in Trypanosoma brucei. Scholars Day 2019, SUNY Brockport, Brockport, NY., (April 10, 2019).
  • Kaptein, V., Pelletier, M., and Noll, M. Variations in Stream Sediment Microbial Communities Across a Natural Climate Gradient in Southeastern Puerto Rico. Geological Society of America Annual Meeting, November 2018.
  • Carlson, C., Pelletier, M., and Ortega, B. Effect of Dietary Magnesium Manipulation on the Gastrointestinal Microbiome of a Mouse Model of Ulcerative Colitis. Rochester Academy of Science Annual Meeting, Geneseo, NY. (September 2018).
  • Illingworth, J., Raichel, A., Green, E., Rossier, R., and Pelletier, M. Effect of Arginine Methylation on the Enzymatic Activity and Functions of TbLpn, a Lipin Homologue from Trypanosoma brucei. Rochester Academy of Science Annual Meeting, Geneseo, NY. (September 2018).
  • Seaburg, J., Schultz, T., and Pelletier, M. Effect of Dietary Magnesium on the Microbiome of the Spleen in a Mouse Model of Ulcerative Colitis. Rochester Academy of Science Annual Meeting, Geneseo, NY. (September 2018).
  • Serbonich, M., Pelletier, M., Disruption of TbLpn expression in T. brucei by RNA interference. Scholars Day 2018, The College at Brockport, Brockport, NY., (April 11, 2018).
  • Wegman, R., Pelletier, M., Effect of Arginine methylation of TbLpn by TbPRMT1. Scholars Day 2018, The College at Brockport, Brockport, NY., (April 11, 2018).
  • Kiser, M., Pelletier, M., Effect of Arginine Methylation of TbLpn by TbPRMT7 on its Enzymatic Activity. Scholars Day 2018, The College at Brockport, Brockport, NY, (April 11, 2018).
  • Flint, A., Pelletier, M., Effect of arginine methylation of TbLpn enzymatic activity and cellular localization in Trypanosoma brucei. Scholars Day 2018, The College at Brockport, Brockport, NY., (April 11, 2018).
  • Michelle Tartaglia, Bernardo Ortega, and Michel Pelletier. Effect of a low magnesium diet on the mouse gut microbial flora. Rochester Academy of Science Annual Meeting, Rochester, NY. (September 2016).
  • Ashley White, Adam Rich, and Michel Pelletier, The effects of gastrointestinal motility on the enteric microbiota in Zebrafish. Rochester Academy of Science Annual Meeting, Rochester, NY. (September 2016).
  • Jennifer J. Taylor, and Michel Pelletier. Identification of a trypanosome lipin homologue function by looking at protein-protein interactions. Scholars Day 2015, The College at Brockport, Brockport, NY. (April 8, 2015).
  • Jennifer J. Taylor, and Michel Pelletier. Cloning of Trypanosome Lipin Homologue for Protein-Protein Interaction Study. New York Six Liberal Arts Consortium Upstate New York Undergraduate Research Conference, Geneva, NY. (September 20, 2014).
  • Pelletier, M., Bigham, W. A., Kocik, C. J., Bellomio, P. M., Tobin, R. A., Fadden, G. J., Peeck, C. L., Tascione, G. M., Schmidt, S. K., Brotsch, M. W., Bablin, N. J., Taylor, J. J. TbLpn, a novel methylated Trypanosoma brucei protein and its role in phospholipid synthesis. 26th Annual Buffalo Conference on Microbial Pathogenesis, The Witebsky Center for Microbial Pathogenesis and Immunology, Buffalo, NY. (April 30, 2014).
  • Pelletier, M., Bellomio, P., Tobin, R. Development of a Non-Radioactive Method to Assay Arginine Methylation of TbLpn in Trypanosoma brucei. Scholars Day 2014, The College at Brockport, Brockport, NY. (April 9, 2014).
  • Pelletier, M., Meyer. The Trypanosoma brucei Protein TbLpn is Methylated in vitro by TbPRMT1. Scholars Day 2014, The College at Brockport, Brockport, NY. (April 9, 2014).
  • Mackenzie M. Meyer, and Michel Pelletier. Trypanosoma brucei lipin homologue is methylated by TbPRMT1. McNair Program Conference, University at Buffalo, NY. (June 2013).
  • Pelletier, M., Draper, J. M. Characterization of the bacterial flora associated with hoof infections in horses. 27th National Conference on Undergraduate Research (NCUR), La Crosse, Wisconsin. (April 11, 2013).
  • Pelletier, M., Snyder, E. In vivo Disruption of TbLpn Expression in Trypanosoma brucei. Scholars Day 2013, The College at Brockport, Brockport, NY. (April 10, 2013).
  • Pelletier, M., Muehleisen, N. TbLpn and phospholipid biosynthesis in Trypanosoma brucei. Scholars Day 2013, The College at Brockport, Brockport, NY. (April 10, 2013).
  • Pelletier, M., Meyer, M. The Trypanosoma brucei Protein TbLpn Forms Oligomers in vitro. Scholars Day 2013, The College at Brockport, Brockport, NY. (April 10, 2013).
  • Pelletier, M., and Frainier, A.S. A Novel Trypanosome Cytoplasmic Protein Interacts With the Enzyme TbPRMT1. Scholars Day 2012, The College at Brockport. (April 11, 2012).
  • Pelletier, M., and Munini, D. Characterization of in vitro Enzymatic Activity of TbLpn and Its Role in Phospholipid Biosynthesis in Trypanosoma brucei. Scholars Day 2012, The College at Brockport, Brockport, NY. (April 11, 2012).
  • Pelletier, M., Rich, A.J., and Blair, I.M. Cloning of the KitA Gene From Zebrafish. Scholars Day 2012, The College at Brockport, Brockport, NY. (April 11, 2012).
  • Pelletier, M., and Karpie, A.R. Expression and Characterization of a Mutant of the Lipin Homolog TbLpn in Trypanosoma brucei. Scholars Day 2012, The College at Brockport, Brockport, NY. (April 11, 2012).
  • Karpie, A.R., and Pelletier, M. Expression and Characterization of a mutant of the lipin homolog TbLpn in Trypanosoma brucei. The National Conference on Undergraduate Research (NCUR), Weber State University, Ogden, Utah. (March 30, 2012).
  • Wiemer, J. M., Frainier, A. S., Pelletier, M. TbLpn and its role in phospholipid Biogenesis in Trypanosoma brucei. Kinetoplastid Molecular and Cell Biology Meeting, Woods Hole, Ma. (April 10, 2011).