# Novel mechanisms and Drosophila model of APOL1-HIV-1 nephropathies in children

> **NIH NIH R01** · UNIVERSITY OF VIRGINIA · 2022 · $423,938

## Abstract

PROJECT SUMMARY
Individuals carrying two APOL1 risk alleles (RA) named G1 or G2 have ~ 30-fold higher odds of developing
HIV-nephropathy (HIVAN) compared to HIV+ controls. Our current knowledge regarding the role of APOL1 in
HIVAN is mostly derived from studies done in cultured renal cells or clinical genetic studies, and new
experimental models are needed to gain a more in depth understanding of the interactions between HIV-1
and the APOL1-RA in vivo. Our pediatric nephrology program has been studying HIV-renal diseases (HIV-
RD) for 25 years and is in a unique position to fill this gap. Recently, we developed Drosophila APOL1-G0
and G1 transgenic (Tg) lines, and found that ectopic expression of APOL1-G1 in nephrocytes (the equivalent
of mammalian podocytes) enhanced the endocytic activity and size of these cells, impaired the acidification
of intracellular vacuoles, and accelerated their death. In addition, we found that HIV-1 induces a low level
productive infection of podocytes cultured from HIV+ children through a dynamin-dependent endocytosis
mechanism that is independent of CD4, and increases the expression of APOL1-G1 in these cells.
Furthermore, we found that overexpression of APOL1-G1 in Tg-flies and cultured podocytes increases the
activity of GTPases involved in endocytosis, regulation of cytoskeletal networks, and cell trafficking. Based
on these findings, we hypothesize that HIV-1 acts as a “second hit” to precipitate HIV-RD in children
by infecting podocytes through an endocytosis mediated mechanism that increases the expression /
activity of the APOL1-RA beyond their toxic threshold levels. In turn, these changes impair key
endocytic, cell trafficking, acidification, and autophagy pathways that disrupt the homeostasis of
podocytes and accelerate their dead, causing proteinuria and HIV-RD. To test this hypothesis, in aim 1
we will determine the phenotype of Drosophila Tg lines expressing APOL1-G0/G1/G2, and the HIV- genes
Tat, Nef, and Vpr, specifically in nephrocytes, and assess how they affect their structure and function. In aim
2, we will define how APOL1-RA and HIV-genes interact in vivo to modulate the function of nephrocytes in
dual Tg-fly lines, define whether APOL1-RA precipitate the death of nephrocytes expressing HIV-genes by
affecting their autophagic flux, and perform RNA-Seq analysis to identify new transcriptional pathways that
regulate these interactions. These findings will be validated in HIV-Tg26 mice carrying the autophagy reporter
construct RFP-EGFP-LC3. In aim 3, we will select the best Drosophila model and perform an RNAi-based
APOL1-HIV genetic interaction screening to identify new pathways that affect the function and survival of
nephrocytes, determine how the APOL1-RA affect the infection of podocytes, and validate all clinical relevant
findings in samples or tissues derived from children with HIV-RD. These studies will identify new
mechanisms through which APOL1-RA and HIV-1 interact to infect podocytes a...

## Key facts

- **NIH application ID:** 10439649
- **Project number:** 5R01DK115968-05
- **Recipient organization:** UNIVERSITY OF VIRGINIA
- **Principal Investigator:** ZHE HAN
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $423,938
- **Award type:** 5
- **Project period:** 2019-07-01 → 2025-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10439649

## Citation

> US National Institutes of Health, RePORTER application 10439649, Novel mechanisms and Drosophila model of APOL1-HIV-1 nephropathies in children (5R01DK115968-05). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10439649. Licensed CC0.

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