Hypoxia hits APOL1 in the kidney

Area of Science:

• Nephrology
• Genetics
• Molecular Biology

Background:

• Individuals of African ancestry with two pathogenic apolipoprotein 1 (APOL1) variants face a high risk of chronic kidney disease (CKD).
• The progression of APOL1-associated nephropathy is highly variable, influenced by systemic factors like interferon response.
• Environmental factors contributing to this 'second-hit' model remain incompletely understood.

Purpose of the Study:

• To investigate the role of hypoxia-inducible factors (HIF) in regulating APOL1 gene expression.
• To identify potential environmental triggers that modulate APOL1 nephropathy.

Main Methods:

• Stabilization of HIF using hypoxia or HIF prolyl hydroxylase inhibitors.
• Analysis of APOL1 transcription in kidney podocytes and tubular cells.
• Identification and characterization of a HIF-interacting regulatory DNA element upstream of APOL1.
• Assessment of HIF's additive effects with interferon and in patient-derived cells.

Main Results:

• Stabilization of HIF activates APOL1 transcription in both podocytes and tubular cells.
• A specific upstream regulatory DNA element interacting with HIF was identified and found to be preferentially accessible in kidney cells.
• HIF-induced APOL1 upregulation was additive to interferon's effects.
• HIF stimulated APOL1 expression in tubular cells from a patient with a kidney disease risk variant.

Conclusions:

• Hypoxia-inducible factors (HIF) represent a significant pathway for modulating APOL1 expression in the kidney.
• Hypoxic insults may act as critical environmental factors exacerbating APOL1-associated nephropathy.
• Targeting HIF pathways could offer novel therapeutic strategies for APOL1-related kidney diseases.