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Kidney Week

Abstract: PO0344

CB11: Mitochondrial Effects in Renal Proximal Tubular Cells

Session Information

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Crossman, Joshua D., The University of Arizona Department of Pharmacology and Toxicology, Tucson, Arizona, United States
  • Schnellmann, Rick G., The University of Arizona Department of Pharmacology and Toxicology, Tucson, Arizona, United States
Background

Oxidative stress and mitochondrial dysfunction are characteristic of many acute and chronic conditions such as acute kidney injury and chronic kidney disease. Renal proximal tubular cells (RPTC) are mitochondria-dense, dependent on oxidative phosphorylation, and are particularly susceptible to injury. Identifying compounds that induce mitochondrial biogenesis (MB) is of increasing importance for the treatment of renal diseases associated with metabolic dysfunction. We investigated the effects of 1-butyl-3-hydroxy-3-[2-oxo-2-(pyridin-2-yl)ethyl]-1,3-dihydro-2H-indol-2-one, (CB11), on MB, mitochondrial dynamics, antioxidant response, and apoptosis in RPTC using a model of oxidant-induced injury.

Methods

In primary cultures of renal proximal tubular cells, we used uncoupled oxygen consumption rate (FCCP-OCR), transmission electron microscopy, immunoblotting, oxidant-induced injury with tert-butyl hydroperoxide (TBHP), and flow cytometry.

Results

CB11 (0.1 nM) treatment increased FCCP-OCR and mitochondria number after 24h. CB11 exposure decreased expression of fusion protein Mfn1 at 1 and 10 nM concentrations. CB11 had no effect on fusion proteins Mfn2 or OPA1 or phosphorylation of fission protein Drp1 at serine residues S637 or S616. Expression of Nrf2 protein decreased with no effect on Nrf2-regulated antioxidant response proteins (e.g. NQO1, GSTM1, GSR1, GPX2). Following a 24h pretreatment with CB11, TBHP-induced injury at 1h was evaluated. CB11 exposure did not prevent the loss of monolayer confluence at 1h post-injury. However, daily exposure prevented further loss of confluence at 48, 72, and 96h. No significant change in apoptosis, as measured by annexin-V positive cells (AnnV+), was seen in control or CB11 exposed samples 48h post-injury. TBHP-induced injury increased AnnV+, while exposure of CB11 did not attenuate AnnV+.

Conclusion

CB11 represents a new and highly potent inducer of MB with a unique signaling pathway in RPTC. Our data reveal that CB11 pretreatment does not prevent oxidant-induced cell death but acts as a RPTC protectant. Future studies will test this compound in AKI and CKD models.

Funding

  • Commercial Support