A focus of the Beatty Group at OHSU is developing new chemical tools for illuminating human diseases.  We have been inspired to use innovative, cross-disciplinary approaches to identify and investigate the molecular basis of human diseases, including tuberculosis (TB) and breast cancer.  Since 2012, we have worked on the following research projects:

1.1   Chemical tools for detecting hydrolase activities in Mtb.

1.2  A new technology for tracking and mapping proteins by light and electron microscopy.

1.3   Imaging the HER signaling network in breast cancer.

1.4  Synthesis of new fluorescent and fluorogenic probes.

 

1.1    Chemical tools for detecting hydrolase activities in Mycobacterium tuberculosis (Mtb).

Beatty group team members: Katie Tallman (PMCB) and Dr. Samantha Levine

Project funding: OHSU School of Medicine, Collins Medical Trust, Medical Research Foundation of Oregon

The human pathogen Mtb is the causative agent of tuberculosis (TB). TB is the deadliest disease in human history, and kills nearly 2 million people every year.  An estimated one-third of humans harbor Mtb in a dormant state. These asymptomatic, latent infections impede TB eradication due to the long-term potential for reactivation. Moreover, three million cases of TB go undiagnosed each year, which contributes substantially to the spread of the disease. 

We are creating new chemical tools and using them to make fundamental discoveries on Mtb hydrolases implicated in latent and active TB infections.  To study TB pathogenesis, we use novel fluorogenic probes to reveal the activity of Mtb-associated hydrolases.  Dormant Mtb has reduced metabolism and enzymatic activity, but hydrolases that remain active facilitate pathogen survival.  As demonstrated by our publications, we have shown that enzyme-activated, fluorogenic probes are powerful tools for tracking hydrolase activities.  In the future, we will continue to characterize hydrolases associated with various stages of infection. 

    

 

1.2 A new technology for tracking and mapping proteins by light and electron microscopy.

Beatty group team members: Julia Doh (PMCB), Dr. Hannah Zane, and Dr. Jon White

Collaborators: Caroline Enns, Claudia Lopez, Dan Zuckerman, and Young Hwan Chang

Project funding: NIH (NIGMS: R01GM122854)

Recent advances in imaging instrumentation and computational analysis have created new opportunities for investigating the molecular basis of diseases with remarkable detail.  It is now possible to interrogate features ranging in size from angstroms to centimeters, which enables investigations into tissue architectures, neuronal connections, organelle coordination, signaling networks, and molecular organization.  These are representative examples of the types of studies that would immediately benefit from a versatile technology for labeling and tracking proteins across size scales.  We foresee an increased reliance on multi-color, multi-scale microscopy for investigating proteins associated with human diseases.  The central obstacle that has decelerated progress in this area is the shortage of methods for labeling proteins for multi-scale microscopy. 

To address this unmet need, we created a new concept for labeling proteins with reporters compatible with multi-scale microscopy.  Long-term, this technology will enable novel investigations into the spatial organization of cells during differentiation and migration, in response to drug treatment or infection, as well as a variety of other scenarios. 

Our strategy combines genetically-encoded peptide tags with a palette of reporter chemistries for labeling cellular nanostructures.  In 2017, we published our first demonstration of using versatile interacting peptide (VIP) tags to label cellular proteins (ChemBioChem, 2017).  Those VIP tags were small, target-specific, easy to use, and compatible with diverse chemical reporters, including bright organic fluorophores (fluorescein, rhodamine, and AF647) and quantum dots.  The reporter chemistry can be selected and optimized for different applications, which makes this technology a powerful resource for imaging studies. In ongoing work, we are developing and validating additional VIP tags.

 

1.3  Imaging the HER signaling network in breast cancer.

Beatty group team members: Dr. Jonathan White and Julia Doh

Collaborators: Tiera Liby, Dr. Jim Korkola and Dr. Joe Gray

Project funding: Women’s Circle of Giving and the Knight Cancer Institute (Pilot Grant)

In a new project, our group is collaborating with Dr. Joe Gray and Dr. Jim Korkola to investigate mechanisms of drug resistance in breast cancer.  HER2 amplification occurs in ~25% of all breast cancer and is associated with poor prognosis.  HER2-targeted therapeutics are clinically available, but their efficacy in patients has not lived up to pre-clinical promise. Multiple reasons for resistance to HER2-targeted inhibitors have been identified, including reactivation of HER2 signaling through feedback mechanisms. HER2 is thought to require HER3 as a partner for oncogenic signaling, as knockout of HER3 phenocopies HER2 knockout in HER2-amplified cells. We are using VIP tags to capture multi-color views of the dynamics of HER2-HER3 signaling. 

 

1.4 Synthesis of new fluorescent and fluorogenic probes.

Beatty group team members: Dr. Samantha Levine and Nick Lopez

Many of the most widely used reporter chemistries are fluorescent or fluorogenic (e.g., “turn-on”) probes.  For imaging within living systems, the most useful fluorophores excite and emit between 600 and 800 nm.  This region is biologically “quiet”, with little endogenous absorption, scattering, or autofluorescence.  However, there are few far-red chemical reporters.  We are using our expertise in color chemistry to develop new fluorescent and fluorogenic probes.  Some of our research in this area used the far-red fluorophore DDAO (Proc. Natl. Acad. Sci. USA 2013, ACS Chem. Biol. 2016, ACS Infect. Dis. 2016, ChemBioChem 2014).  We have also synthesized far-red carbazines that can be converted into enzyme-activated fluorophores (Chem. Commun., 2016).  In the future, we team will continue to develop novel molecular imaging agents for biomedical research.