In this section
Robert Marr, PhD
Dr. Marr received his undergraduate degree in applied biochemistry from the University of Guelph, Guelph, Ontario, Canada. Afterward, he did his graduate work in the laboratory of Dr. Frank Graham at McMaster University in Hamilton, Ontario, Canada where he worked on gene therapy for cancer. After receiving his PhD in Molecular Biology Genetics and Cancer from McMaster he moved to the Salk Institute for Biological Studies in La Jolla California. There his work in the laboratory of Dr. Inder Verma was primarily on the application of gene transfer technology to the study and treatment of Alzheimer’s disease.
The overlying area of Dr. Marr’s interests lay in the study of neurodegenerative diseases. More specifically his focus is on Alzheimer’s disease and the use of gene transfer vectors as a tool to investigate specific gene function(s) in the brain as it relates to Alzheimer’s. The derivation of potentially new therapeutic approaches to Alzheimer’s disease is also an area of focus for Dr. Marr, as well as the role of Alzheimer’s related genes in the process of traumatic brain injury. Finally, his laboratory has been working on the use in induced human neurons to model aspects of dementia and for their application to regenerative medicine.
He has been awarded the Lee Nielson Roth Award for Cancer Research from McMaster University (1997), and received awards from the Medical Research Council of Canada (1998), and the Canadian Institutes of Health Research (2000). He also received an Excellence in Research Award from the American Society for Gene Therapy (2003).
Current Research Support
Past Research Support
“Investigation of the role of MMEL (NEP2) in protection from Alzheimer's disease.”
The goal of this project was to examine to role of MMEL expression in AD and its therapeutic potential.
“SEP (NEP2) and Aβ Degradation: Assessment of in vivo role in protecting against Alzheimer disease.”
The goal of this project was to determine if endogenous mouse SEP expression is involved in Aβ degradation.
My work has primarily dealt with molecular mechanisms of neurodegeneration (mainly Alzheimer’s disease) with an emphasis on identifying molecular markers and therapies. Deficiencies in clearance of the amyloid-beta (Ab) peptide are thought to contribute to the development of Alzheimer’s disease (Marr et al. 2014. PMID: 25165447)(Marr RA (2014) Editorial on, “Amyloid-beta clearance in Alzheimer's disease”. Front. Aging Neurosci. 6:310.). The endopeptidase neprilysin (Nep) has been shown to be a key enzyme regulating Aß (Marr et al. 2003. PMID: 12657655). However, evidence suggests the existence of other proteases that contribute to the clearing of Aß (Marr et al. 2010. PMID: 20088804).Neprilysin-2 (Nep2) is the closest known homolog to Nep and is expressed in the brain; therefore, Nep2 is a good candidate for an enzyme that cooperates with Nep to control cerebral Aß levels. Our group has identified a new property for the Nep2 enzyme, in that it can degrade the Ab peptide in humans (Huang et al. 2008. PMID: 18571334). We also found that Nep2 functions in vivo to significantly reduce Ab peptide levels in the rodent brain (Hanson et al. 2010. PMID: 20941644; Hafez et al. 2011. PMID: 21224067). Finally, we showed that the expression and activity of Nep2 is altered in association with preclinical Alzheimer’s disease (Huang et al. 2012. PMID: 22008264). This finding suggests that Nep2 quantitation might serve as an early predictor of risk for developing the disease. My work on therapeutic applications to Alzheimer’s disease also extends to the use of antisense technology to specifically target genes linked to disease pathogenesis. Finally, in collaboration with DePaul University, I am also working on the therapeutic application of gene-manipulation of novel amyloid precursor protein (APP) interacting proteins (Philibert et al. 2014. PMID: 25346686) for Alzheimer’s disease.
In addition to my work as part of the neuroscience discipline, I am also a center investigator at the Center for Stem Cell and Regenerative Medicine here at RFUMS. My work with the center includes the investigation of the cross-talk between neurogenic pathways and neurodegeneration. Related to this, we have reported that gene transfer of the pro-neurogenic F-spondin gene reduced Alzheimer’s-like pathology in mice (Hafez et al. 2012. PMID: 22863679). Our interests also extend to the use of gene transfer vectors to “reprogram” cells in vitro and in vivo to produce induced neurons for disease modeling and therapeutic applications. Related to this we have used retroviral vectors for the manipulation of endogenous progenitor cell fate in the brain (Klempin et al. 2012. PMID: 22162276). Lastly, this work has implications for the study and treatment of traumatic brain injury which we are pursuing in collaboration with investigators at DePaul University.
Peer Reviewed Publications
- SF Bazarek, M Thaqi, P King, AR Mehta, R Patel, CA Briggs, E Reisenbigler, JE Yousey, EA Miller, GE Stutzmann, RA Marr, and DA Peterson (2023). Engineered neurogenesis in naïve adult rat cortex by Ngn2-mediated neuronal reprogramming of resident oligodendrocyte progenitor cells. Front. Neurosci. doi.org/10.3389/fnins.2023.1237176. PMC10471311
- S Mustaly-Kalimi , W Gallegos , R Marr, A Gilman-Sachs, DA Peterson, I Sekler, and GE Stutzmann (2022). Protein mishandling and impaired lysosomal proteolysis generated through calcium dysregulation in Alzheimer's disease. Proc. Natl. Acad. Sci. USA. 119(49): e2211999119. PMID: 36442130
- KC Maigler, TJ Buhr, CS Park, SA Miller, DA Kozlowski, RA Marr† (2020). Assessment of the effects of altered amyloid-beta clearance on behavior following repeat closed-head brain injury in APP humanized mice. J Neurotrauma. 38(5):665-676. PMID: 33176547
- S Schrank, J McDaid, CA Briggs, S Mustaly-Kalimi, D Brinks, A Houcek, O Singer, V Bottero, RA Marr*, GE Stutzmann* (2020). Human-Induced Neurons from Presenilin 1 Mutant Patients Model Aspects of Alzheimer's Disease Pathology. Int J Mol Sci. 21(3): 21(3):1030. PMC7037274 *co-senior and co-corresponding authors
- PH Lim, SL Wert, E Tunc-Ozcan, R Marr, A Ferreira, EE Redei (2018). Premature hippocampus-dependent memory decline in middle-aged females of a genetic rat model of depression. Behav Brain Res. 353:242-249. PMID: 29490235
- Chang JL, Hinrich AJ, Roman B, Norrbom M, Rigo F, Marr RA, Norstrom EM, Hastings ML. (2018) Targeting Amyloid-β Precursor Protein, APP, Splicing with Antisense Oligonucleotides Reduces Toxic Amyloid-β Production. Mol Ther. 26(6):1539-1551. PMID: 29628304
- HS Villarroel, M Bompolaki, J Mackay, AM Tapia, S Michaelson, R Leitermann, R Marr, J Urban, and W Colmers (2018). NPY induces stress resilience via down-regulation of Ih in principal neurons of rat basolateral amygdala. Journal of Neuroscience. 38(19):4505-4520 PMC5943978
- Patrick H. Lim, SL Wert, E Tunc-Ozcan, R Marr, A Ferreira, and EE Redei (2018). Premature hippocampus-dependent memory decline in middle-aged females of a genetic rat model of depression. Behav Brain Res. doi: 10.1016/j.bbr.2018.02.030. PMID: 29490235
- Jamnia N, Urban JH, Stutzmann GE, Chiren SG, Reisenbigler E, Marr R, Peterson DA, Kozlowski DA. (2017) A Clinically Relevant Closed-Head Model of Single and Repeat Concussive Injury in the Adult Rat Using a Controlled Cortical Impact Device. J Neurotrauma. 34(7):1351-1363. PMID: 27762651
- AJ Hinrich, FM Jodelka, JL Chang, D Brutman, A Bruno, CA Briggs, BD. James, GE Stutzmann, DA Bennett, SA Miller, F Rigo, RA Marr, ML Hastings (2015). Therapeutic correction of apoER2 splicing in Alzheimer’s disease mice using antisense oligonucleotides. EMBO Molecular Medicine, 8(4):328-45. PMID: 26902204
- JA Bonds, Y Kuttner-Hirshler, N Bartolotti, MK Tobin; M Pizzi, RA Marr, O Lazarov (2015). Presenilin-1 dependent neurogenesis regulates hippocampal learning and memory. PLoS One, 10(6):e0131266. PMID: 26098332
- KD Philibert, RA Marr, EM Norstrom, MJ Glucksman (2014). Identification and characterization of Aβ peptide interactors in Alzheimer’s disease by structural approaches. Frontiers in Aging Neuroscience. 6(265): PMID: 25346686
- DM Hafez, JY Huang, JC Richardson, E Masliah, DA. Peterson, RA. Marr† (2012). F-spondin gene transfer improves memory performance and reduces amyloid-β levels in mice. Neuroscience, 223: 465–472. PMID: 22863679
- F Klempin, RA Marr, DA Peterson (2012). Modification of Pax6 and Olig2 in adult hippocampal neurogenesis selectively induces stem cell fate and alters both neuronal and glial populations. Stem Cells, 30(3):500-9. PMID: 22162276
- JY Huang, DM Hafez, BD James, DA Bennett, RA Marr† (2012). Altered NEP2 expression and activity in mild-cognitive impairment and Alzheimer’s disease. Journal of Alzheimer’s Disease, 28(2):433-41. PMID: 22008264
- A Bruno, J Huang, DA Bennett, RA Marr, GE Stutzmann, and M Hastings (2011). Altered ryanodine receptor expression in mild cognitive impairment and Alzheimer's disease. Neurobiology of Aging, 33(5):1001.e1–1001.e6. PMID: 21531043
- BJ Spencer, RA Marr, R Gindi, R Potkar, S Michael, A Adame, E Rockenstein, IM Verma, E Masliah (2011). Peripheral delivery of a CNS targeted, metallo-protease reduces Aß toxicity in a mouse model of Alzheimer's disease. PLoS One, 6(1): 1-12 e16575. PMID: 21304989
- A Gadadhar, RA Marr, O Lazarov (2011). Presenilin-1 regulates neural progenitor cell differentiation in the adult brain. Journal of Neuroscience, 31(7):2615-23. PMID: 21325529
- D Hafez, JY Huang, AM Huynh, S Valtierra, E Rockenstein, AM Bruno, B Lu, L DesGroseillers, E Masliah, RA Marr† (2011). Neprilysin-2 is an important beta-amyloid degrading enzyme. American Journal of Pathology, 178(1): 306-312. PMID: 21224067
- LR Hanson, D Hafez, AL Svitak, RB Burns, X Li, WH Frey, and RA Marr† (2010). Intranasal phosphoramidon increases beta-amyloid levels in wild-type and NEP/NEP2 deficient mice. Journal of Molecular Neuroscience, 178(1): 306-312. PMID: 20941644
- J Rose, L Crews, E Rockenstein, A Adame, M Mante, L Hersh, FH Gage, B Spencer, R Potkar, R Marr, and E Masliah (2009). Neuropeptide Y fragments derived from neprilysin processing are neuroprotective in a transgenic model of Alzheimer's disease. Journal of Neuroscience, 29(4):1115–1125. PMID: 19176820
- B Spencer , RA Marr , E Rockenstein , L Crews , A Adame , R Potkar , C Patrick , FH Gage , IM Verma and E Masliah (2008). Long-term neprilysin gene transfer is associated with reduced levels of intracellular Abeta and behavioral improvement in APP transgenic mice. BMC Neuroscience, 9:109. PMID: 19014502
- JY Huang, AM Bruno, CA Patel, AM Huynh, KD Philibert, MJ Glucksman, RA Marr† (2008). Human membrane metallo-endopeptidase-like protein (MMEL) degrades both Ab42 and Ab40. Neuroscience, 155(1):258-62. PMID: 18571334
- SS El-Amouri, H Zhu, J Yu, R Marr, IM Verma, MS Kindy (2008). Neprilysin: An enzyme candidate to slow the progression of Alzheimer's disease. American Journal of Pathology, 172(5):1332-1344. PMID: 18403590
- I Hovatta, RS Tennant, R Helton, RA Marr, O Singer, JM Redwine, EE Schadt, JA Ellison, IM Verma, DJ Lockhart and C Barlow (2005). Glyoxalase 1 and glutathione reductase regulate anxiety in inbred mouse strains. Nature, 438(7068):662-6. PMID: 16244648
- O Singer*, RA Marr*, E Rockenstein, L Crews, NG Coufal, FH Gage, IM Verma, and E Masliah (2005). Targeting BACE1 with siRNAs ameliorates Alzheimer disease neuropathology in a transgenic model. Nature Neuroscience, 8(10):1343-9. PMID: 16136043 *both authors contributed equally
- JC Dodart, RA Marr, M Koistinaho, BM Gregersen, S Malkani, IM Verma, SM Paul (2005). Gene delivery of human apolipoprotein E alters brain Ab burden in a mouse model of Alzheimer’s disease. Proc. Natl. Acad. Sci. U S A., 104(4):1211-1216. PMID: 15657137
- M Hashimoto, E Rockenstein, M Mante, L Crews, P Bar-On, FH Gage, R Marr, and E Masliah (2004). An antiaggregation gene therapy strategy for Lewy body disease utilizing b-synuclein lentivirus in a transgenic model. Gene Therapy, 11(23): 1713-1723. PMID: 15483670
- HM Kankkonen, E Vähäkangas, RA Marr, T Pakkanen, A Laurema, P Leppänen, J Jalkanen, IM Verma, S Ylä-Herttuala (2004). Long-term lowering of serum cholesterol levels in LDL-receptor deficient WHHL rabbits by gene therapy. Molecular Therapy, 9(4):548-556. PMID: 15093185
- RA Marr, H Guan, E Rockenstein, M Kindy, FH Gage, I Verma, E Masliah, LB Hersh (2004). Neprilysin regulates amyloid-b peptide levels. Journal of Molecular Neuroscience, 22(1-2):5-11. PMID: 14742905
- RA Marr, E Rockenstein, A Mukherjee, MS Kindy, LB Hersh, FH Gage, IM Verma, and E Masliah (2003). Neprilysin gene transfer reduces human amyloid pathology in transgenic mice. Journal of Neuroscience, 23(6):1992-1996. PMID: 12657655 (Featured in The Lancet 361(9363):1107 and Drug Discovery Today 8(11): 474).
- Z Chen, H Huang, T Chang, S Carlsen, A. Saxena, R Marr, Z Xing, J Xiang (2002). Enhanced HER-2/neu-specific antitumor immunity by cotransduction of mouse dendritic cells with two genes encoding HER-2/neu and alpha tumor necrosis factor. Cancer Gene Therapy, 9(9): 778-786. PMID: 12189528
- RA Marr, M Hitt, J Gauldie, WJ Muller, and FL Graham (1999). A p75 TNF receptor specific mutant of murine TNFa expressed from an adenovirus vector induces an antitumour response with reduced toxicity. Cancer Gene Therapy, 6(5): 465-474. PMID: 10505857
- J Gauldie, PJ Sime, Z Xing, B Marr, and GM Tremblay (1999). TGFß gene transfer to the lung induces myofibroblast presence and pulmonary fibrosis. Current Topics in Pathology, 93: 35-45. PMID: 10339897
- PJ Sime, RA Marr, D Gauldie, Z Xing, BR Hewlett, FL Graham, and J Gauldie (1998). Transfer of tumour necrosis factor-alpha to rat lung induces severe pulmonary inflammation and patchy interstitial fibrogenesis with induction of transforming growth factor-beta1 and myofibroblasts. American Journal of Pathology, 153(3): 825-832. PMID: 9736031
- RA Marr, M Hitt, WJ Muller, J Gauldie, and FL Graham (1998). Tumour therapy using adenovirus vectors expressing human TNFa. International Journal of Oncology, 12(3): 509-515. PMID: 9472086
- XF Lei, Y Ohkawara, MR Stampfli, C Mastruzzo, RA Marr, D Snider, Z Xing, and M Jordana (1998). Disruption of antigen-induced inflammatory responses in CD40 ligand knock out mice. Journal of Clinical Investigations, 101(6): 1342-1353. PMID: 9502776
- RA Marr, CL Addison, D Snider, WJ Muller, J Gauldie, and FL Graham (1997). Tumour immunotherapy using an adenoviral vector expressing a membrane-bound mutant of murine TNFa. Gene Therapy, 4(11): 1181-1188. PMID: 9425441
† corresponding author
- KM Kim, M Thaqi, DA Peterson, and RA Marr† (2021). Induced Neurons for Disease Modeling and Repair: A Focus on Non-fibroblastic Cell Sources in Direct Reprogramming. Front Bioeng Biotechnol. 2021;9:658498. PMID: 33777923
- RA Marr†, DM Hafez (2014). Amyloid-beta and Alzheimer’s disease: The role of neprilysin-2 in amyloid-beta clearance. Frontiers in Aging Neuroscience. 6(187):1-7. PMID: 25165447
- O Lazarov† and RA Marr† (2013). Of mice and men: Neurogenesis, cognition and Alzheimer’s disease. Frontiers in Aging Neuroscience. 5:43 doi: 10.3389/fnagi.2013.00043. PMID: 23986699
- RA Marr, RM Thomas, and DA Peterson (2010). Insights into neurogenesis and aging: Potential therapy for degenerative disease? Future Medicine, 5(4): 527-541. PMID: 20806052
- Invited - RA Marr† and BJ Spencer (2010). NEP-like endopeptidases and Alzheimer’s disease. Current Alzheimer’s Research, 7:223-229. PMID: 20088804
- O Lazarov, RA Marr (2009). Neurogenesis and Alzheimer's disease: At the crossroads. Experimental Neurology, 223:267-281. PMID: 19699201
- B Spencer, E Rockenstein, L Crews, R Marr, E Masliah (2007). Novel strategies for Alzheimer's disease treatment. Expert Opin Biol Ther. 7(12):1853-67. PMID: 18034651
- Marr RA (2014). Editorial on, “Amyloid-beta clearance in Alzheimer’s disease.” Frontiers in Aging Neuroscience. doi: 10.3389/fnagi.2014.00310.
- Marr, RA (2015). The Amyloid Beta Precursor Protein and Cognitive Function in Alzheimer’s Disease. In Genes, Environment and Alzheimer’s Disease, O. Lazarov and G Tesco, eds, Elsevier / Academic Press, Section I, Chapter 4, pp. 98-117.
- Marr, RA (2011). MS: 133 | Neprilysin-2. In Handbook of Proteolytic Enzymes, 3rd edition, ND Rawlings and G Salvesen, eds, Elsevier, Ch. 128, pp. 620-624.
- Assistant Dean for Research
- Chair, Institutional Biosafety Committee
- Director, Molecular Quantification Laboratory