Previous Projects

The top 4 causes of blindness in the United States are all age-related diseases. Although we understand a lot about vision, how the eye generates energy as we age is less well understood. My main thesis project focused on how the retina and a neighboring cell type, the retinal pigment epithelium (RPE), use glucose and glutamine in aging. We found that glucose metabolism in tissue explants examined ex vivo were remarkably stable with aging, as was oxidative and reductive glutamine metabolism through the Krebs cycle in the retina. Only minimal changes were seen in aged RPE oxidative glutamine metabolism. We hypothesized that this indicates the retina and RPE (broadly) retain metabolic capacity with age. That future studies examining aging metabolism in the eye must do so in vivo to determine if the environment of the aged eye could impair uptake and processing of nutrients. This study suggests that given access to sustenance, these tissues age well!

Tsantilas KA, et al. An Analysis of Metabolic Changes in the Retina and Retinal Pigment Epithelium of Aging Mice. Investigative Ophthalmology & Visual Science. 2021. PMID: 34797906.

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In a pair of highly collaborative studies driven by Dr. Mariya Sweetwyne and Dr. Monica Sanchez-Contreras we examined how aging mitochondrial DNA mutations occur and how different tissues are impacted. Many studies have sought to do this, but none had used a high fidelity DNA sequencing method (In this case, duplex sequencing!) in combination with tandem application to 8 different tissues isolated by researchers that specialized in their biology. That’s what we sought to do! I isolated retinas and retinal pigment epithelium (RPE)-choroid complexes as part of this interdisciplinary team. We identified a mutational gradient associated with aging in mitochondrial DNA, and found that there is significant diversity in cross-tissue mutational burdens and mutation signatures and that they vary by tissue with age.

Sanchez-Contreras M, Sweetwyne MT, Kohrn BF, Tsantilas KA, et al. A replication-linked mutational gradient drives somatic mutation accumulation and influences germline polymorphisms and genome composition in mitochondrial DNA. Nucleic Acids Research. 2021. PMID: 34614167.

Sanchez-Contreras M, Sweetwyne MT, Tsantilas KA, et al. The multi-tissue landscape of somatic mtdna mutations indicates tissue specific accumulation and removal in aging. eLife. 2023. 30;505884.

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As a graduate student, I worked in the laboratory of Dr. James B. Hurley. Early in my PhD, I worked on a study led by a colleague, Dr. Mark Kanow, to better understand the metabolic ecosystem of the retina and its neighboring cell types. We used a combination of immunohistochemistry, live imaging of retinal slices, and metabolomics. In short, we found that retina rapidly consumes glucose and produces lactate, which may then be consumed by surrounding cell types.

Mitochondria in vertebrate cone photoreceptors often form large clusters with mitochondria of varied shapes and sizes that change with circadian rhythm. My colleague Dr. Michelle Giarmarco led an interdisciplinary study in the Hurley Lab using zebrafish and mice to better understand the role of mitochondria and metabolism in this process. We took measurements over full 24-hour cycles to cover daily circadian rhythm. We found that the shape, distribution, and metabolism of these mitochondria changes with circadian rhythm

I also contributed metabolic flux analyses to a study led by Dr. Ammaji Rajala in the laboratory of Dr. Raju V. S. Rajala. When Pyruvate Kinase M2 (PKM2) is knocked-out in mouse rod photoreceptors, their retinas accumulate glycolytic intermediates intermediates that are generated before the formation of pyruvate from PEP via PKM2.

Kanow M, Giarmarco M, Jankowski C, Tsantilas K, et al. Biochemical adaptations of the retina and retinal pigment epithelium support a metabolic ecosystem in the vertebrate eye. eLife. 2017. PMID: 28901286.

Giarmarco MM, Brock DC, Robbings BM, Cleghorn WM, Tsantilas KA, et al. Daily mitochondrial dynamics in cone photoreceptors. Proceedings of the National Academy of Sciences USA. 2020. PMID: 33144507.

Rajala A, Wang Y, Brush RS, Tsantilas K, et al. Pyruvate kinase M2 regulates photoreceptor structure, function, and viability. Cell Death & Disease. 2018. PMID: 29445082

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I worked on different human diseases and sample types including cells, tissues, and biofluids as an intern and technician at the Integrated Mass Spectrometry – Shared Resources (then called the Center for Proteomics) at TGen with Dr. Patrick Pirrotte.

My group performed mass spectrometry analysis for a study led by Dr. Lena Yang Li and Dr. Robert Bowser regarding amyotrophic lateral sclerosis (ALS). RNA-binding proteins are known to be involved in ALS, and they are found aggregated in inclusion bodies. Dr. Yang used immunoprecipitation coupled to MS to characterize protein-protein interactions of RBM45 in cells. In the binding partners, we found some known to ALS alongside novel proteins.

Finally, Dr. Claudia Fredolini, the team at the Center of Applied Proteomics and Molecular Medicine at George Mason University, and the team at TGen used hydrogel nanoparticles to identify novel biomarkers for invasive ductal carcinoma. The study team identified 32 differentially expressed proteins specific to invasive ductal carcinoma, and 4 (TGA2B, FLNA, RAP1A, and TLN-1) were verified in an independent cohort and classified patients with 100% sensitivity and 85% specificity.

Li Y, Collins M, An J, Geiser R, Tegeler T, Tsantilas K, et al. Immunoprecipitation and mass spectrometry defines an extensive RBM45 protein-protein interaction network. Brain Research. 2016. PMID: 26979993

Fredolini C, Pathak KV, Paris L, Chapple KM, Tsantilas KA, et al. Shotgun proteomics coupled to nanoparticle-based biomarker enrichment reveals a novel panel of extracellular matrix proteins as candidate serum protein biomarkers for early-stage breast cancer detection. Breast Cancer Research. 2020. PMID: 33267867

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