RUI: Activity-based Mapping of Cellular Cathepsins B and L - An introduction to Chemical Biology in Undergraduate Curriculum

Cuny Queens College, Flushing NY

Investigators

Abstract

With this RUI award, the Chemistry of Life Processes Program in the Division of Chemistry is funding Professor Sanjai Kumar to investigate the function of two important enzymes found in human cells. A cell is a complex yet highly organized system where thousands of events are coordinated with great precision at any given moment. These processes are elegantly orchestrated by proteins, the main centers of activity of the cell. It is estimated that the total number of proteins in a human cell is between 250,000 to one million. Assigning individual functions to the various proteins is a challenging endeavor, especially since a protein may be active or inactive depending on the status of the cell. This status of a protein is often controlled by a group of enzymes known as proteases. The human genome has the capacity to produce about 550 proteases. How, why, and where these proteases function in the complex cellular environment remains poorly understood. This project involves examining two closely-related proteases of the cysteine cathepsin family of enzymes; cathepsin B and L. Selective probes are made to target these cathepsins so that their function can be understood. This research endeavor provides educational opportunities with hands-on research experience to graduate and undergraduate students. The laboratory environment is structured for an enhanced interdisciplinary experience for both undergraduate and graduate students. Additionally, there are outreach activities incorporating research training for students from Queensborough Community College and Bard High School Early College in New York. Special emphasis is given to include students from underrepresented groups in science disciplines, women, and veterans. Human cysteine cathepsins comprise a small group of eleven enzymes that are important in maintaining cell homeostasis, growth, differentiation, and survival. One of the main challenges of cathepsin biology is in assigning specific function to individual enzymes in a given cellular context. This is mainly because several functional redundancies and overlapping substrate specificities have been shown to exist in individual cell types. Since newly synthesized cellular cathepsins are subject to post-translational modifications, thereby leading to alteration of their activities (and hence function), specific investigative tools are needed for activity-based interrogation of cellular function in live cells. This project is developing selective tagless activity-based probes (TABPs) of two closely related cysteine cathepsins; cathepsin L and B. The developed TABPs are used in differential and quantitative mapping of cathepsin B and L activities in live pancreatic and neuronal cells. The knowledge gained from these studies significantly advances the functional understanding of cellular processes involving human cathepsin B and L.