Our laboratory develops novel chemical tools to address important questions in biology and medicine.  Our main goal is to advance our understanding of underlying mechanisms of human diseases with the focus on the following projects:

Project 1. Cancer Metabolic Reprogramming

Cancer metabolic reprogramming is an important hallmark of cancer. It relies of the fact that cancer tissue possesses several important metabolic features, such as differential utilization of many essential metabolites. Cancer metabolic reprogramming is required for malignant transformation, tumor development, invasion and metastasis. Its complex and dynamic nature has been recognized as one of the major challenges for effective cancer treatment. Therefore, a better understanding of metabolic dependencies in specific tumor types can provide a path for improved cancer treatments.

 

However, no efficient methodologies currently exist that allow noninvasive imaging and quantification of the uptake of essential metabolites in animal models of disease. To address the unmet need for nutrient uptake imaging tools, we decided to develop a novel platform based on a combination of versatile “click” chemistry reactions with noninvasive, ultrasensitive bioluminescent imaging techniques.

 

The results will lead to the generation of novel, effective treatments; therefore, this novel platform has high clinical applicability. Due to its versatile nature, application of the platform can be expended to studies of many other important human pathologies in which changes in metabolism play a key role, such as diabetes, neurodegenerative diseases, nonalcoholic steatohepatitis, and many others. Please see the first demonstration of the platform recently published in Nature Methods (2019).

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Project 2. Development of new tools for probing mitochondrial activity in cells and living animals

Mitochondria are essential organelles that provide eukaryotic cells with energy in the form of ATP generated through aerobic respiration. In addition, mitochondria play important role in multiple biological processes including cell differentiation, cell cycle control, cell survival, neuronal protection, and aging. Mitochondrial dysfunction contributes to a remarkably wide range of human diseases including cancer, Alzheimer’s disease, Parkinson’s disease, diabetes, ischemia perfusion injury, steatohepatitis, sepsis, Huntington’s disease, and many others. As more information associating mitochondrial dysfunction with human diseases emerges, the development of new tools to interrogate this important organelle becomes increasingly important.

 

Mitochondrial membrane potential (ΔΨm) is one of the main indicators of mitochondrial function but its direct role in many human pathologies still remain illusive due to  the lack of tools for imaging of ΔΨm levels both in vitro and in vivo. This issue represents a major obstacle to our understanding of the role of this important function in a range of important human diseases, making the drug discovery process complex and less efficient.

 

To address this unmet need, our lab developed novel bioluminescent probe that allows noninvasive longitudinal imaging and quantification of ΔΨm levels both in vitro and in vivo. The approach is based on combination of sensitive bioluminescent imaging and a powerful “click” reaction chemical tool and has wide applicability in the field of biomedical research. Please see our manuscript recently published in Nature Chemical Biology (2020). This novel ΔΨm imaging probe was successfully applied to elucidate the mechanism of action of a novel anti-cancer drug for the treatment of triple negative breast cancer (Nature Biotechnology, 2020)

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Project 3. Novel tools to unravel enzymatic functions of gut microbiota

The gut microbiota plays a major role in human health and has been characterized as an extremely dynamic and chemically diverse community. Gut microbes significantly impact host physiology by influencing host homeostasis including metabolism, neurobiology, and immune function. The microbiome-produced enzymes play central role in regulation of many essential functions of gut microbiome. For example, bile salt hydrolase (BSH) plays a central role in human health and is responsible for modulation of multiple host signaling pathways, bile detoxification, and gastrointestinal persistence of bacteria. Despite the importance of BAs in host health and disease, the underlying mechanisms by which the gut microbiota enzymes drive their composition and modification are largely unknown. Another important family of gut microbiota enzymes is nitroreductase (NTR) that is known to metabolize nitrosubstituted compounds and quinones using NADH or NADPH as reducing agents. They are important for the development of novel antibiotics being the main target for the treatment of infections caused by several pathogenic bacteria and parasides, NTR enzymatic activity in gut microbiota is also linked to carcinogen production and etiology of colorectal cancer.

 

However, monitoring of enzymatic activity in the gastro-intestinal tract is very challenging given the unique chemical environment, variable distribution of the microbiota, and highly dynamic nature of the microbiota. Currently, no methods exist for noninvasive real-time evaluation of enzymatic activities of the gut microbiota in its intact environment. The existing methods involve ex vivo evaluation of fecal samples, studies of isolated cultured bacteria (in vitro tests), and in silico methods. However, all of these approaches have significant drawbacks for assessment of the composition and function of the microbiota.

 

To address this unmet need, we developed a novel quantitative optical readout-based method that is bereft of these disadvantages. The design of the method is based on bioluminescence imaging and caged-luciferin approach that relies on “caging” luciferin with a small chemical group. First, we adopted this strategy to create a novel assay for non-invasive real-time imaging of NTR activity of gut microbiota (PLOS One, 2015). Next, developed a set of novel “caged” luciferin probes for real-time non-invasive monitoring of BSH activity in bacteria, mice, humans, and clinical samples. Using this assay, we showed for the first time that consumption of particular prebiotics increase BSH activity of the gut microbiota. We also successfully demonstrated application of this novel tool as non-invasive diagnostic test to predict the clinical status of inflammatory bowel disease (IBD) patients. This work represents the first application of functional bioluminescent probes in humans paving the path for clinical translation of these powerful tools for various clinical applications (Science Advances, 2021).

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