Kidney Week

Abstract: TH-PO393

Alternative Oxidase Expression Restores Kidney Progenitor Differentiation in Mice with Mitochondrial Complex lll Disruption

Session Information

• Development, Organoids, Injury, and Regeneration
  October 24, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Development, Stem Cells, and Regenerative Medicine

• 600 Development, Stem Cells, and Regenerative Medicine

Authors

• Bessho, Ryoichi, Vanderbilt University School of Medicine, Nashville, Tennessee, United States

Ryoichi Bessho, MD, PhD

• Kobayashi, Hanako, Vanderbilt University School of Medicine, Nashville, Tennessee, United States

Hanako Kobayashi, PhD

• Haase, Volker H., Vanderbilt University School of Medicine, Nashville, Tennessee, United States

Volker H. Haase, MD, DrMed

Background

Oxidative metabolism in mitochondria generates ATP through oxidative phosphorylation, regulates cellular differentiation and gene expression through intermediary metabolism and produces reactive oxygen species (ROS). The specific roles of different mt functions in kidney development and pathogenesis are not well understood. We previously reported that disruption of mitochondrial (mt) complex III in cap mesenchyme resulted in severe kidney dysplasia and perinatal death (Guan N, et al. Kidney Int 2022). For the disruption of mt complex III, we targeted ubiquinone binding protein QPC using the Six2-Cre transgene (Six2-Qpc^-/- mutants). This resulted in decreased proliferation of renal progenitors and their complete failure to differentiate into tubular epithelium. QPC inactivation disrupted mt electron flux and oxidative phosphorylation and decreased total kidney tricarboxylic acid (TCA) cycle metabolites and amino acid levels.

Methods

To investigate the contribution of TCA cycle dysfunction to the Six2-Qpc^-/- phenotype, we generated mice expressing alternative oxidase (AOX) in Qpc^-/- renal progenitors. AOX is derived from sea squirt and restores mt electron transport and TCA cycle flux. We performed morphological, immunohistochemical, gene expression, as well as targeted and untargeted metabolomic analyses of kidneys at postnatal day 0.

Results

AOX expression in Qpc^-/- renal progenitors rescued postnatal lethality. Immunohistochemical staining and gene expression analyses of tubular differentiation markers, such as megalin, demonstrated restoration of proximal tubular differentiation. AOX expression, however, did not completely restore kidney weight to normal values and all AOX-expressing Six2-Qpc^-/- mutants died by postnatal day 14. The results from metabolomic analyses will be presented in detail at the meeting.

Conclusion

Taken together, restoration of TCA cycle flux by AOX induced tubular differentiation in mice with mt electron chain disruption in SIX2 nephron progenitors but did not generate functional adult kidneys. Although, our studies suggest a critical role for TCA cycle flux and TCA cycle-regulated gene expression in nephron progenitor differentiation, other mt functions, such as oxidative phosphorylation and ROS production, are required for cell proliferation and postnatal growth of the kidney.

Funding

• NIDDK Support