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Abstract: TH-OR004

Orphan Nuclear Receptor COUP-TFII Regulates Pericyte Detachment in AKI

Session Information

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Li, Li, Brigham and Women's Hospital/Harvard Medical School , Boston, Massachusetts, United States
  • Galichon, Pierre, Brigham and Women's Hospital/Harvard Medical School , Boston, Massachusetts, United States
  • Ichimura, Takaharu, Brigham and Women's Hospital/Harvard Medical School , Boston, Massachusetts, United States
  • Bonventre, Joseph V., Brigham and Women's Hospital/Harvard Medical School , Boston, Massachusetts, United States
Background

Pericytes are essential to maintain capillary integrity. Acute kidney injury (AKI) causes pericyte detachment from capillaries, triggering endothelial cell injury, capillary rarefaction, and hypoxia, contributing to interstitial fibrosis. The molecular mechanisms underlying pericyte detachment and subsequent transition to myofibroblasts are poorly understood. We hypothesized that Chicken Ovalbumin Upstream Promoter-Transcription Factor II (COUP-TFII) is important for maintaining kidney pericyte function by preventing detachment/activation in the setting of kidney injury.

Methods

COUP-TFII mRNA was measured by quantitative real-time PCR (qRT-PCR) and protein by immunostaining at different times after unilateral ischemia reperfusion (IRI). In vitro, knockdown of COUP-TFII was attained by transfecting a small interfering RNA (siRNA) into CH310T1/2 (pericyte-like cells). Angiopoietin 1 (Ang1, a angiotrophic protein produced by pericyte to maintain vessel stability) expression was evaluated. In addition, we generated CRISPR-cas9 COUP-TFII knock out and tetracycline-inducible COUP-TFII overexpressing CH310T1/2 cells. By modulating COUP-TFII expression, we studied the effect on αSMA expression (a marker of myofibroblast) and cell migration (using scratch motility assay) in CH310T1/2 cells.

Results

COUP-TFII mRNA and protein expression initially decreased at 4 hours after IRI, returned to baseline at 24 hours, and was significantly increased at day 21 post-IRI. In vitro, knockdown of COUP-TFII by siRNA resulted in decreased Ang1 expression in CH310T1/2 cells. Furthermore, knock out of COUP-TFII resulted in increased αSMA mRNA expression and promoted migration compared to wild type CH310T1/2 cells. In contrast, over-expression of COUP-TFII decreased αSMA mRNA expression and inhibited migration compared to control-transfected cells.

Conclusion

Down regulation of COUP-TFII in AKI is an early event regulating pericyte fate. It results in: 1) decreased Ang1 expression, which is important for pericyte-endothelial crosstalk; 2) increased αSMA expression and cell migration, which is important for the pericyte to myofibroblast transdiferentiation. Maintaining COUP-TFII expression may stabilize pericytes, protect endothelial cells in the early phase of AKI, and prevent vascular rarefaction, secondary ischemia and subsequent fibrosis.

Funding

  • NIDDK Support