2. Academic Validation
  3. A fluorogenic, peptide-based probe for the detection of Cathepsin D in macrophages

A fluorogenic, peptide-based probe for the detection of Cathepsin D in macrophages

  • Commun Chem. 2023 Nov 2;6(1):237. doi: 10.1038/s42004-023-01035-9.
Maria Rodriguez-Rios 1,  Brian J McHugh 2,  Zhengqi Liang 1,  Alicia Megia-Fernandez 1 3,  Annamaria Lilienkampf 1,  David Dockrell 2,  Mark Bradley 4
Affiliations

Affiliations

  • 1 School of Chemistry, University of Edinburgh, David Brewster Road, EH9 3FJ, Edinburgh, UK.
  • 2 University of Edinburgh Centre for Inflammation Research, Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh BioQuarter, Edinburgh, EH16 4TJ, UK.
  • 3 Organic Chemistry Department, Faculty of Sciences, University of Granada, Avda. Fuente Nueva S/N, Granada, 18071, Spain.
  • 4 Precision Healthcare University Research Institute, Queen Mary University of London, Empire House, 67-75 New Road, London, E1 1HH, UK. [email protected].
PMID: 37919467 DOI: 10.1038/s42004-023-01035-9
Abstract

Cathepsin D is a protease that is an effector in the immune response of macrophages, yet to date, only a limited number of probes have been developed for its detection. Herein, we report a water soluble, highly sensitive, pH insensitive fluorescent probe for the detection of Cathepsin D activity that provides a strong OFF/ON signal upon activation and with bright emission at 515 nm. The probe was synthesised using a combination of solid and solution-phase chemistries, with probe optimisation to increase its water solubility and activation kinetics by addition of a long PEG chain (5 kDa) at the C-terminus. A BODIPY fluorophore allowed detection of Cathepsin D across a wide pH range, important as the protease is active both at the low pH found in lysosomes and also in higher pH phagolysosomes, and in the cytosol. The probe was successfully used to detect Cathepsin D activity in macrophages challenged by exposure to bacteria.

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