The Jovanovic-Talisman Lab within Beckman Research Institute of City of Hope employs novel, quantitative imaging techniques and nanobiology to investigate biological mechanisms, develop new diagnostic assays, and advance therapeutics.
Quantitative single molecule localization microscopy (qSMLM)
To investigate biological processes that are critical to the progression of cancer and other diseases we use quantitative single molecule localization microscopy (qSMLM). qSMLM is a fluorescence-based imaging technique that evaluates single molecules with nanoscale precision. In typical qSMLM experiments, target molecules are detected with fluorescent reporters like optical highlighter proteins or antibodies labeled with photoswitchable dyes. Since these imaging agents have intricate photophysical properties, one major challenge in the field has been relating the number of localizations of reporters to the detected number of target proteins. To address this, we recently developed a new surface assay for molecular isolation (SAMI), that allows us to robustly count individual molecules. We use SAMI and other methodological advancements to study important biological mechanisms, aid in development of novel therapeutic agents, and advance diagnostics.
qSMLM for imaging of patient tissues
We advance qSMLM to assess patient specimens: cells from excised tissues and extracellular vesicles from biofluids.
We apply advanced qSMLM methods to quantify both the density and nano-organization of membrane receptors in cancer. We are currently focusing on assessing G-protein coupled receptors and receptor tyrosine kinases. Recently, we used fluorescently labeled trastuzumab to quantify human epidermal growth factor receptor 2 (HER2) in breast cancer. We have combined qSMLM with tissue touch preparation to assess human tumor samples. We developed a straightforward analytical protocol and algorithms designed for rapid data analysis; these advancements allowed us to obtain quantitative results for patients within one day. Results from these studies demonstrated a significant correlation between classical HER2 screening (i.e., fluorescence in situ hybridization, FISH) and HER2 assessment with qSMLM. Moreover, we recently assessed how the molecular features of HER2 varied with the therapy response. According to our results, the therapy response was associated with high detected HER2 densities and clustering. In the future, qSMLM could provide key data to complement the current diagnostic standards.
Both healthy and diseased cells continuously shed extracellular vesicles (EVs). These membrane encapsulated nanoscale particles regulate intercellular communications through their cargo (e.g., nucleotides, metabolites, lipids, and proteins). EVs contain a wealth of biological information and can reflect disease pathology. Moreover, EVs can be collected frequently and non-invasively from almost any accessible biofluid, such as blood, saliva, and urine. EVs are thus an attractive target for the early detection and monitoring of various diseases.
Patient biofluids contain complex mixtures of EVs; they originate from a wide variety of cells and tissues. A major challenge has been the detection of disease-specific EVs or tissue-specific EVs within the background of ‘other’ EVs. To address this, we are advancing methodology to isolate and characterize EV populations enriched in receptors that have high expression in either specific tissue/cell type or disease. Our qSMLM approach uniquely allows us to assess both the size and the molecular content of individual EVs with high sensitivity. Since limited information on EVs is currently available at the molecular level, we expect these studies to help address EV heterogeneity and advance EVs as biomarker sources in a clinical setting.
qSMLM for probing molecular mechanisms/advancing drug development
We have applied qSMLM to probe nano-organization of opioid receptors in alcohol use disorders and to delineate the mechanisms of nucleocytoplasmic transport.
New drugs are urgently needed to treat alcohol use disorders (AUDs). Long-term alcohol use can lead to cancer and diabetes; it can significantly shorten lifespan. However, current therapies to treat this disease are at best marginally effective. We have used qSMLM to assess how physiologically relevant concentrations of alcohol perturb the dynamic organization of signaling domains that harbor opioid receptors. Additionally, we are studying how the organization of these domains is affected when we administer potential therapeutic reagents.
The nucleus and cytoplasm communicate through nuclear pore complexes (NPCs) that are embedded in the nuclear envelope. NPCs are selectively permeable to certain macromolecules and thus regulate nucleocytoplasmic transport. To efficiently regulate selective transport, each NPC can shuttle thousands of molecules every second. Errors in this high throughput process can lead to large-scale cellular dysregulation observed in a number of diseases, including neurodegenerative disorders and solid tumors. Despite these high stakes, resolution of specific mechanism(s) of transport has been challenging. To advance our understanding of these mechanisms, we apply qSMLM to obtain single molecule data on NPC barrier mimics and on NPCs from intact nuclei. The resolution of nucleocytoplasmic transport mechanisms may ultimately provide novel targets and opportunities for drug development.
Principal Investigator: Tijana Jovanovic-Talisman, Ph.D.
Associate Professor, Department of Molecular Medicine
Andras Saftics received his BS degree in biochemical engineering (2012) and his MS degree in chemical engineering (2014) from the Budapest University of Technology and Economics. After graduation, he did his Ph.D. research in Dr. Robert Horvath’s Nanobiosensorics Laboratory at the Centre for Energy Research, where he focused on the development of functional coatings for label-free optical biosensor applications. Upon earning his Ph.D. degree at the George A. Olah Doctoral School of the Budapest University of Technology Economics (2019) and continuing research at the Nanobiosensorics Laboratory as a research fellow, Andras joined the laboratory of Dr. Tijana Jovanovic-Talisman at City of Hope as a postdoctoral fellow in 2020. In the Jovanovic-Talisman Lab, Andras is developing quantitative single molecule localization microscopy based methods for the characterization of disease-derived extracellular vesicles. He is excited to do research in an interdisciplinary team to advance vesicle related diagnostic technologies.
Wai Mak completed her Bachelor of Science degree in chemistry at the University of California, Santa Cruz. During this time, she worked as an undergraduate researcher in Professor Nader Pourmand’s lab which focused on developing nanopipette sensors to probe analytes within live single cells. After realizing how fun research can be, Wai decided to continue her career by pursuing a chemistry PhD at University of California, Los Angeles. Under the direction of Professor Richard Kaner, Wai studied the production and characterization of two-dimensional nanomaterials and its uses in a wide range of materials applications. As a postdoctoral fellow in Professor Tijana Jovanovic-Talisman’s lab, Wai is currently using super resolution microscopy to probe lateral organization of membrane proteins to investigate potential therapeutics for alcohol use disorders.
Eugenia Romano graduated from University of Naples Federico II in Italy in 2017 with a M.Sc. in Pharmaceutical Chemistry and Technologies. During her master’s thesis she joined the group of Professor Paolo Antonio Netti at the Istituto Italiano Di Tecnologia working on polymer-based engineered nanostructures for in vivo application in diagnosis and therapy. In 2021 she obtained her Ph.D. in Industrial Product and Process Engineering. The aim of her thesis research was to study the dynamic and physical properties of Extracellular Vesicles lipidic bilayer for theragnostic application. She subsequently joined the lab of Dr. Jovanovic-Talisman where she is assessing extracellular vesicles as biomarker sources.
Ima Ghaeli is an interdisciplinary research scientist at nano-/biointerfaces. She got her Doctoral Degree in Biomedical engineering from University of Porto, Portugal. After her PhD, she joined the UBNP group at INL Institute, Portugal as a postdoc fellow. There, Ima developed a custom-built near-field based imaging technique and analyzed optical and magnetic properties of advanced surfaces on enhancing axial resolution. In 2022, she joined Jovanovic-Talisman Lab at City of Hope, as a postdoctoral fellow, working towards advancing super-resolution microscopy methods to detect disease-specific and organ-specific extracellular vesicles.
Ima Ghaeli, Ph.D. Postdoctoral Fellow
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In 2018 Shelby Thompson, PhD graduated from Texas Tech University with their Bachelors of Science in Chemistry, followed by their PhD in Analytical Chemistry in 2022, also from Texas Tech University. They completed their PhD project in the laboratory of Dr. Dimitri Pappas, where they conducted research involving the synthesis and characterization of fluorescent nanoparticles and their potential use in localization-based super-resolution microscopy. Shelby joined the laboratory of Dr. Tijana Jovanovic-Talisman as a Postdoctoral Fellow and is excited to start the next stage of their career and explore super-resolution microscopy in the context of medical research.
Irell & Manella Graduate School of Biological Sciences PhD Student
Sarah Abu-Elreich graduated from University of California, Davis in 2011 with a bachelor’s degree in genetics. Post-graduation, she worked as a research assistant in the Stem Cell Unit in Riyadh, Saudi Arabia. Her previous interests focus on deciphering implicated pathways in osteogenic, adipogenic, and chondrogenic differentiated human mesenchymal stem cells. After numerous successful publications, Sarah pursued a master’s degree at the Cancer Research Lab of Jason Bush, Ph.D. at California State University, Fresno in 2017. The aim of her thesis research was to better understand the dysfunction of the HER2 signaling pathway in breast cancer. In 2019, she earned a Master of Science in Biology with Honors. As a graduate student of City of Hope’s Irell & Manella Graduate School of Biological Sciences, Sarah is conducting her dissertation research in the laboratory of Tijana Jovanovic-Talisman, Ph.D. developing and utilizing methods to characterize cargo of extracellular vesicles using quantitative single molecule localization microscopy towards diagnostics applications.
Sarah Abu-Elreich Irell & Manella Graduate School of Biological Sciences PhD Student
626-256-HOPE, ext. 65598 email@example.com
Irell & Manella Graduate School of Biological Sciences MSTM Student
Nan Jiang graduated with a Bachelor of Science in Pharmacy (Biochemistry and Pharmacology) from China Pharmaceutical University and with Bachelor of Science in Biochemistry and Pharmacology with first class honors from the University of Strathclyde, UK. Currently, she is a graduate student at City of Hope’s Irell & Manella Graduate School of Biological Science. Her master's thesis in the lab of Dr. Jovanovic-Talisman is focused on characterizing extracellular vesicles from breast cancer cells for ultimate diagnostic applications.
Irell & Manella Graduate School of Biological Sciences MSTM Student
626-256-HOPE, ext. 65598 firstname.lastname@example.org
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