Activity-Based Probes for the High Temperature Requirement A Serine Proteases

Abstract

The high temperature requirement A (HTRA) family of serine proteases mediates protein quality control. These proteins process misfolded proteins in several diseases including Alzheimer's disease (AD) and Parkinson's disease (PD). While their structures and activation mechanisms have been studied, the precise details of the regulation of their activity under physiological conditions have not been completely elucidated, partly due to the lack of suitable chemical probes. In the present study, we developed novel activity-based probes (ABPs) targeting the HTRAs and demonstrated their utility in the monitoring and quantification of changes in enzyme activity in live cells. Using our probes, we found the activity of HTRA1 to be highly elevated in an AD-like cell-based model. We also observed the active HTRA2 in live cells by using a mitochondrion-targeted probe. We believe that our probes can serve as a useful tool to study the role of human HTRAs in neurodegenerative diseases.

Chemical Probes and Activity-Based Protein Profiling for Cancer Research

“…Misfolded HTRA proteins are abundantly observed in Alzheimer’s disease (AD), Parkinson’s disease (PD), apoptotic signaling, and cancer cell invasion. Application of this probe to mitochondria has shown significant efficacy in monitoring HTRA2 in living cells [ 31 ]. Verhelst et al recently developed an activity-based probe utilizing alkyne-substituted benzoxazin-4-ones for serine protease activity monitoring [ 32 ].…”

Recent Advances in Organelle-Targeted Fluorescent Probes

“…The probe visualized changes in mitochondrial viscosity and polarity upon treatment with ionophores and electron transport complex inhibitors. Nam et al used a peptoid-based mitochondria-targeting group that is conjugated to an activity-based probe (30) to label the active mitochondrial enzyme HTRA2 (the hightemperature requirement A) serine protease in live cells [71]. This probe is particularly useful for monitoring enzyme activity changes in living cells without the use of cell permeabilizing agents or multiple antibodies and is applicable for diagnostic imaging.…”