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

Area of Science:

• Molecular Biology
• Cell Biology
• Immunology

Background:

• Angiotensin-converting enzyme 2 (ACE2) is crucial for renin-angiotensin system regulation and SARS-CoV-2 entry.
• Previous ACE2 protein studies were limited by unreliable antibody specificity.
• Understanding ACE2 protein expression is vital for cellular biology and virology.

Approach:

• Developed a sensitive and specific flow cytometry assay for quantifying cellular ACE2 protein.
• Applied the assay to various cell lines, revealing significant expression heterogeneity.
• Investigated heterogeneity at the mRNA level, identifying proximal promoter initiation.

Key Points:

• ACE2 protein is heterogeneously expressed within isogenic cell populations.
• Expression is heritable across cell generations but subject to gradual drift.
• RNA-seq identified distinct transcriptomes for ACE2-expressing versus non-expressing cells.
• Epigenetic mechanisms likely regulate ACE2 gene expression.

Conclusions:

• The new assay provides a validated method for detecting cell-surface ACE2 protein.
• Findings support epigenetic regulation of ACE2 expression.
• Identified specific molecular pathways linked to ACE2 expression in HuH7 cells.