Rational correction of pathogenic conformational defects in HTRA1

Area of Science:

• Molecular Biology
• Biochemistry
• Neuroscience
• Genetics

Background:

• Loss-of-function mutations in the homotrimeric serine protease HTRA1 are linked to cerebral vasculopathy.
• Defective trimer assembly of HTRA1 impairs its enzymatic activity, contributing to disease pathogenesis.
• Cerebral vasculopathy presents a significant challenge due to limited therapeutic options for correcting underlying protein defects.

Purpose of the Study:

• To develop and validate strategies for the functional correction of HTRA1 trimer assembly defects.
• To investigate both protein-based and small-molecule approaches for restoring HTRA1 enzymatic activity.
• To assess the therapeutic potential of these strategies in preclinical models of HTRA1-associated vasculopathy.

Main Methods:

• Identification and characterization of an HTRA1 variant that promotes trimer formation.
• In vitro enzymatic assays to measure HTRA1 activity.
• In vivo genetic experiments using Htra1^R274Q mice to assess protein corrector efficacy.
• Screening and identification of supramolecular chemical ligands and peptidic ligands that modulate HTRA1 assembly and activity.

Main Results:

• A novel HTRA1 variant was identified that enhances trimer formation and restores enzymatic activity in vitro.
• Expression of the protein-based corrector in trans successfully stabilized HtrA1-R274Q in mice, restoring brain vasculature proteomic signatures.
• Supramolecular chemical ligands and a specific peptidic ligand were found to shift the monomer-trimer equilibrium towards active trimers and activate HTRA1 monomers, respectively.

Conclusions:

• Independent approaches, including protein-based and chemical strategies, can effectively correct HTRA1 trimer assembly defects.
• These findings demonstrate the feasibility of targeted protein repair for HTRA1-associated cerebral vasculopathy.
• The study opens new avenues for developing tailored therapeutic strategies for protein misfolding and aggregation diseases.