ACE2 protein expression within isogenic cell lines is heterogeneous and associated with distinct transcriptomes

Area of Science:

• Cell Biology
• Immunology
• Virology

Background:

• Angiotensin-converting enzyme 2 (ACE2) is crucial for renin-angiotensin system regulation and serves as the SARS-CoV-2 cellular receptor.
• Previous ACE2 protein studies were limited by unreliable commercial antibody specificity, hindering accurate expression analysis.

Purpose of the Study:

• To develop and validate a sensitive, specific assay for quantifying cellular ACE2 protein abundance.
• To investigate the heterogeneity of ACE2 protein expression within cell populations.

Main Methods:

• Development of a flow cytometry-based assay for specific detection of cell surface ACE2 protein.
• Application of the assay to multiple cell lines to assess ACE2 expression heterogeneity.
• RNA sequencing (RNA-seq) to compare transcriptomes of ACE2-expressing versus non-expressing cells.

Main Results:

• The novel assay demonstrated sensitive and specific detection of ACE2 protein on single cells.
• Significant cellular heterogeneity in ACE2 protein expression was observed, with only a subset of cells expressing detectable levels.
• ACE2 expression heterogeneity is linked to mRNA transcripts initiated from the proximal promoter and exhibits heritable, yet dynamic, epigenetic regulation.

Conclusions:

• A validated method for specific ACE2 protein detection on single cells was established.
• Findings support an epigenetic mechanism underlying ACE2 gene regulation and expression heterogeneity.
• Distinct transcriptomic profiles associated with ACE2 expression were identified, highlighting specific cellular pathways.