Measuring peroxidasin activity in live cells using bromide addition for signal amplification

Area of Science:

• Biochemistry
• Cell Biology
• Extracellular Matrix Biology

Background:

• Peroxidasin (PXDN) is crucial for crosslinking collagen IV, a key component of basement membranes.
• Disruptions in basement membrane integrity, linked to collagen IV or PXDN alterations, can cause developmental issues and diseases.
• Studying PXDN activity in physiological and pathological conditions is therefore highly significant.

Purpose of the Study:

• To develop and validate a novel method for measuring peroxidasin (PXDN) activity in live cells.
• To establish a sensitive assay for real-time analysis of PXDN function within cellular environments.

Main Methods:

• Adapted the Amplex Red assay with signal amplification for live-cell PXDN activity measurement.
• Utilized bromide addition to enhance signal, with carnosine as a scavenger to confirm the mechanism (HOBr formation).
• Validated the assay using pharmacological inhibition (Brefeldin A) and genetic approaches to confirm PXDN specificity.

Main Results:

• Successfully measured PXDN activity in live cells for the first time.
• Demonstrated signal amplification via bromide addition, likely through hypobromous acid (HOBr) formation.
• Confirmed assay specificity through inhibition and genetic manipulation, showing a direct correlation with PXDN activity.

Conclusions:

• The modified Amplex Red assay provides a robust tool for quantifying PXDN activity in live cells.
• This new method enables deeper investigation into the role of PXDN in various (patho)physiological contexts.
• Opens avenues for studying basement membrane dynamics and related diseases at the cellular level.