Samuel Todd Lamitina, PhD
- Associate Professor of Pediatrics
Lamitina has led a research program utilizing the nematode C. elegans to explore the cellular and molecular mechanisms of stress response pathways, protein misfolding, and age-related human disease. His lab is primarily known for defining the mechanisms of the hypertonic stress response in C. elegans. Recently, his lab has developed C. elegans as a model system for studying a new class of peptides that are translated from repeat expansion mutations that give rise to neurodegenerative diseases such as ALS, frontotemporal dementia, and Huntington’s disease. Since becoming an independent PI in 2006, Lamitina has trained 13 undergraduate and high school students, three Ph.D. graduate students, and five postdoctoral fellows. All of his post-graduate level trainees have gone on to either purse additional academic research training or establish their own independent laboratories. He has established and led successful multidisciplinary collaborations between biologists, physicists, mechanical engineers, and mathematicians.
Lamitina currently serves as the Associate Vice Chair for Basic Research with the Department of Pediatrics at the University of Pittsburgh. One of Lamitina’s longest research projects is defining the molecular genetics of the osmotic stress response, which is an important contributor to many physiological and pathophysiological states. Lamitina discovered that worms accumulate the osmolyte glycerol to adapt to hypertonicity via the upregulate of the key glycerol biosynthetic enzyme, glycerol-3-phosphate dehydrogenase gpdh-1. Hypertonic stress causes rapid (15 minutes) and substantial (1000x) upregulation of gpdh-1 in C. elegans epithelial cells. He showed that many other genes are also regulated by osmotic stress and that the overall pattern of gene expression is very similar to that seen when C. elegans are infected by pathogenic bacteria and fungi, suggesting mechanistic and physiological similarities in these stress responses. Through an unbiased forward genetic screen he also discovered an extracellular matrix pathway that functions in adults to control gpdh-1 expression. Notably, such pathways are unlikely to be identified in more traditional cell culture based studies since these complex ECM pathways are not faithfully reproduced. He discovered that osmotic stress induces a unique type of protein damage and that cells may utilize this distinct type of protein damage to discriminate between different types of proteotoxic stress. Most recently, his lab has performed unbiased forward genetic screens for mutations in genes essential for gpdh-1 induction by hypertonic stress and unexpectedly discovered a role for the conserved O-GlcNAcylation enzyme ogt-1 and the process of mRNA polyadenylation.
Another research area of Lamitina’s laboratory involves development of models of human diseases. C. elegans offers an outstanding opportunity to model aspects of human disease, either through the study of related nematode genes or through expression of human genes in the worm system. We have utilized these strengths to develop worm models of Cystic Fibrosis, ALS, Alzheimer’s disease, and Muscular Dystrophy. Recently, we develop new C. elegans models for novel peptides derived from CAG repeats in Huntington’s (and other) disease and the GGGGCC repeat in C9orf72 in ALS/FTD. Genetic screens are identifying novel and evolutionarily conserved factors required for the toxicity of these peptides. Through work with his collaborators, Lamitina has discovered that these genes discovered through C. elegans genetic screens play similar roles in mammalian neurons. Targeting of these genes, either genetically or pharmacologically, could lead to new therapies for these currently incurable diseases.
Professional and Scientific Society Memberships
- American Society of Nephrology, 2006-Present
- Genetics Society of America, 2006-Present
- American Physiological Society, 2009-Present
- Society for Neuroscience, 2013-Present
Education & Training
- BS, Biology, Emory University, 1995
- PhD, Cell and Developmental Biology, Emory University, 2002
- Post-Doctoral fellowship, Physiology, Vanderbilt University, 2002-2006
Morton, E.A. and T. Lamitina. Caenorhabditis elegansHSF-1 is an essential nuclear protein that forms stress granule-like structures following heat shock. Aging Cell, 2013 February 12(1):112-20. PMCID: PMC3552056
Tanis, J.E., Ma, Z., Krajacic, P., He, L., Foskett, J.K., Lamitina, T. CLHM-1 is a Functionally Conserved and Conditionally Toxic Ca2+-Permeable Ion Channel in Caenorhabditis elegans. J. of Neuroscience, 2013 July 33(30):12275-86. PMCID: PMC3721838
Krajacic, P., Pistilli, E.E., Tanis, J.E., Khurana, T.S.*, Lamitina, T.*. Fer-1/Dysferlin promotes cholinergic signaling at the neuromuscular junction in C. elegansand mice. Biology Open2013 October 2(11):1245-52. * - Co-corresponding authors. PMCID: PMC3828772.
Jablonski, A., Lamitina, T., Liachko, N.F., Sabatella, M., Liu, J, Ostrow, L.W., Gupta, P., Wu, C-Y., Doshi, S., Mojsilovic-Petrovic, J., Lans, H., Wang, J., Kraemer, B., Kalb, R.G. Loss of RAD-23 Protects Against Models of Motor Neuron Disease by Enhancing Mutant Protein Clearance. J. of Neuroscience, 2015, Oct 21;35(42):14286-306. PMCID: PMC4683688
Das, R., Melo, J.A., Thondamal, M., Morton, E., Cornwell, A.B., Crick, B, Kim, J.H., Swartz, E.W., Lamitina, T., Douglas, P., Samuelson A.V. The homeodomain-interacting protein kinase HPK-1 preserves protein homeostasis and longevity through master regulatory control of the HSF-1 chaperone network and TORC1-restricted autophagy in Caenorhabditis elegans. PLoS Genetics, 2017, Oct 16;13(10):e1007038. PMCID: PMC5658188
Rudich, P., Snoznik, C., Oosten, J., Monaghan, J., Pandey, U., Lamitina, T. Nuclear localized C9orf72-associated arginine containing dipeptides exhibit age-dependent toxicity in C. elegans. Human Molecular Genetics, 2017, Dec 15:26(24):4916-4928
Rudich, P., Snoznik, C., Puleo, N., and Lamitina, T. Methods for measuring RAN peptide toxicity inC. elegans. J Vis Exp. 2020 Apr 30;(158). doi: 10.3791/61024. PMID: 32420986
Rudich, P., Watkins, S., and Lamitina, T. PolyQ-independent toxicity associated with novel translational products from CAG repeat expansions. PLoS One. 2020 Apr 2;15(4):e0227464. doi: 10.1371/journal.pone.0227464. PMID: 32240172
Puleo, N. and Lamitina, T. The conserved multi-functional nuclear protein dss-1/Sem1is required for C9orf72-associated ALS/FTD dipeptide toxicity. microPublication Biology. 2020. In Press
Urso, S. and Lamitina, T. Post-transcriptional regulation of the osmotic stress response by the GlcNAc transferase OGT1. bioRxiv2020.05.01.072033; doi: https://doi.org/10.1101/2020.05.01.072033(Under peer review)
Snoznik, C., Mojsilovic-Petrovic, J., Rudich, P., Oosten, J., Kalb, R.G., Lamitina, T. A genome-wide RNAi screen identifies the nuclear ubiquitin ligase adaptor SPOP as a conserved regulator of C9orf72 dipeptide toxicity. In preparation