Abstract: TH-PO0284
Nuclear Translocation of a Cleaved N-Terminal APOL1-G1 Fragment Drives Podocyte Toxicity in HIV-Associated Nephropathy
Session Information
- Glomerular Diseases: Cell Biology
October 22, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1401 Glomerular Diseases: Mechanisms, including Podocyte Biology
Authors
- Li, Jinliang, Children's National Hospital, Washington, District of Columbia, United States
- Yu, Jing, University of Virginia, Charlottesville, Virginia, United States
- Zhu, Junyi, University of Maryland Baltimore, Baltimore, Maryland, United States
- Xu, Lian, Children's National Hospital, Washington, District of Columbia, United States
- Das, Jharna R., Children's National Hospital, Washington, District of Columbia, United States
- Han, Zhe, University of Maryland Baltimore, Baltimore, Maryland, United States
- Ray, Patricio E., University of Virginia, Charlottesville, Virginia, United States
Background
APOL1-G1 risk variants increase susceptibility to HIV-associated nephropathy (HIVAN), but the mechanisms through which APOL1-G1 injures podocytes in the context of HIV-1 remain incompletely understood. Current models emphasize membrane-associated toxicity mediated by full-length APOL1 risk variants; however, inflammatory stress may also alter APOL1 localization, proteolytic processing, and downstream signaling. We hypothesized that HIV-1 and proinflammatory cytokines promote proteolytic processing of APOL1-G1, generating fragments capable of causing additional toxicity.
Methods
Podocytes cultured from the urine of children with HIVAN (HIVAN podocytes) were used to generate APOL1-G1/G1 and APOL1-knockout (KO) cell lines. Immunohistochemistry, qRT-PCR, bulk RNA-seq, proteomics, Western blotting, lipid raft isolation, and nuclear fractionation studies were performed. CRISPR-Cas9 editing was used to insert GFP in frame into exon 5 of endogenous APOL1-G1 to define its localization and cytotoxicity following exposure to HIV-1, TNF-α, and IFN-γ. In vivo toxicity was assessed using nephrocyte-specific expression of APOL1-G1 transgenes in Drosophila.
Results
Endogenous APOL1-G1 localized predominantly to a perinuclear endoplasmic reticulum-associated cytosolic compartment, lipid rafts, and vacuolar structures. HIV-1, TNF-α, and IFN-γ increased APOL1-G1 expression and cytotoxicity. APOL1-KO HIVAN podocytes were more permissive to HIV infection, suggesting a partial antiviral role for APOL1-G1. Unexpectedly, GFP-APOL1-G1 localized to the nuclei of select podocyte clones exhibiting enhanced inflammatory and cytotoxic transcriptional signatures. Proteomic analysis of nuclear fractions identified an N-terminal APOL1-G1 fragment (~14 kDa). Expression of either full-length APOL1-G1 fused to a nuclear localization signal or the N-terminal fragment markedly increased podocyte death. In vivo, nephrocyte-specific expression of GFP-APOL1-G1 significantly reduced nephrocyte survival.
Conclusion
These studies identify a previously unrecognized APOL1-G1 injury pathway in HIVAN podocytes in which proteolytic processing generates a toxic N-terminal fragment capable of nuclear accumulation. Our findings suggest that APOL1-G1–mediated podocyte injury involves both established membrane-associated toxicity and a distinct nuclear fragment–mediated cytotoxic pathway.
Funding
- NIDDK Support