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Emery
Usher
BMMB Graduate Student-Showalter Lab
Image of Grace Usher standing next to the Bruker 850
The Showalter Lab

About Me

I obtained a B.S. with Honors in Chemistry with a minor in Engineering Science from Clarkson University (Potsdam, NY) in 2016. My undergraduate thesis research focused on the functionalization of gold nanoparticles with chemotherapeutic agents for applications in tumor ablation therapy through combinatorial drug/radiation treatments. During undergrad, I interned in the laboratory of Jeff Kelly at The Scripps Research Institute where I studied the kinetic stability of misfolded amyloidogenic antibody light chains. I joined the BMMB program at Penn State in 2016 and affiliated with the Showalter lab.

 

Research Interest

The Showalter Laboratory is interested in how intrinsically disordered proteins (IDPs)—proteins that do not adopt a stable folded structure—contribute to eukaryotic gene regulation. We employ various biophysical, biochemical, and cell biological tools to characterize the interactions and functions of IDPs. Broadly, we aim to understand how the unique properties IDPs permit their critical roles in various regulatory processes.

 

Research Summary

In the context of our broad laboratory interest in the roles of IDPs in gene regulation, my project focuses on a sequence-specific transcription factor, Pdx1. Pdx1 activates insulin transcription in pancreatic β cells to help facilitate glucose homeostasis in the body. Therefore, the appropriate regulation of Pdx1 is critical to the proper health and function of the pancreas. The ubiquitin ligase adaptor SPOP interacts with the disordered C-terminus of Pdx1 and inhibits Pdx1 function. It is the goal of my project to probe the interaction between Pdx1 and SPOP to elucidate the molecular mechanisms of and the cellular signals that lead to Pdx1 inhibition.

Image showing the interaction between Pdx1 and SPOP to elucidate the molecular mechanisms of and the cellular signals that lead to Pdx1 inhibition.

I have employed orthogonal biophysical and cell biological approaches to understand the functional interaction between Pdx1 and SPOP. NMR spectroscopy methods optimized for the study of IDPs provides residue-level insight into local structural features, intermolecular interaction, and post-translational modification (ie, phosphorylation). We gain valuable information about IDP post-translational modification—a common regulatory signal—through MALDI-TOF mass spectrometry performed on-site (https://www.huck.psu.edu/core-facilities/proteomics-and-mass-spectrometry-core-facility). Equilibrium binding experiments detected by fluorescence anisotropy allow us to understand the strength the interaction between various Pdx1 and SPOP constructs. We further validate our in vitro findings in cell culture through immunofluorescence to assess protein localization. Such complementary approaches afford us a diverse set of experiments by which to test our hypotheses.

 

Programs and Training Centers

 

Honors and Awards

  • NIH Ruth L. Kirschstein NRSA Predoctoral Fellow, 2019-2022
     
  • Biophysical Society Student Research Achievement Award, Intrinsically Disordered   Proteins category, 2019
     
  • Eukaryotic Gene Regulation Predoctoral Training Program T32 Fellowship, 2018-2019