Abstract: SA-OR081

Role of COUP-TFII in Pericyte Activation and Kidney Fibrosis

Session Information

Category: Acute Kidney Injury

  • 001 AKI: Basic

Authors

  • Li, Li, Brigham & Women's Hospital/Harvard Medical School, Boston, Massachusetts, United States
  • Xiao, Xiaoyan, Brigham & Women's Hospital/Harvard Medical School, Boston, Massachusetts, United States
  • Ichimura, Takaharu, Brigham & Women's Hospital/Harvard Medical School, Boston, Massachusetts, United States
  • Wilflingseder, Julia, Brigham & Women's Hospital/Harvard Medical School, Boston, Massachusetts, United States
  • Bonventre, Joseph V., Brigham & Women's Hospital/Harvard Medical School, Boston, Massachusetts, United States
Background

Genetic fate mapping studies suggest that pericytes are the main source of myofibroblasts enriched in injury-induce kidney fibrosis. The transcriptional network that controls the pericyte-myofibroblast transdifferentiation is poorly understood. Chicken Ovalbumin Upstream Promoter-Transcription Factor II (COUP-TFII) is a transcription factor critical to the kidney development. It is broadly detected in the mesenchyme of developing organs and has a profound impact on organogenesis and cell fate determination.

Methods

We measured COUP-TFII mRNA by quantitative real-time PCR (qRT-PCR) and protein by Western Blot from normal C57BL/6 mouse kidneys and at different times after unilateral ureter obstruction (UUO). To assess the origin of COUP-TFII+ cells, we crossed Forkhead Box D1 (Foxd1)-Cre driver mice to tdTomato reporter mice to genetically label the Foxd1-derived stromal cells. In vitro, knockdown of COUP-TFII was attained by transfecting a small interfering RNA (siRNA) into CH310T1/2 (pericyte-like cells). COUP-TFII and αSMA expression was evaluated in tissue by immunostaining and in siRNA-transfected CH310T1/2 by RT-PCR.

Results

In non-injured kidney, expression of COUP-TFII is sparsely distributed in interstitial cells, Bowman’s capsule and to a lesser extent in tubules. Cells expressing COUP-TFII are PDGFRβ+ (pericytes/fibroblasts) and are adjacent to CD31+ (endothelial) cells. Most COUP-TFII+ cells are localized in the region of Foxd1-derived stromal cells. Upon injury, COUP-TFII expression is significantly increased in αSMA+ cells (myofibroblasts) localized within the fibrotic region. COUP-TFII expression did not overlap with F4/80 (macrophages) staining. Both mRNA and protein levels of COUP-TFII increased at 5, 7 and 10 days after UUO and are associated with increased levels of αSMA at the same time point. In vitro, knockdown of COUP-TFII by siRNA results in decreased αSMA expression in pericyte-like cells.

Conclusion

COUP-TFII is expressed at basal levels in non-injured kidney in Foxd1-derived stromal cells. Upon injury, COUP-TFII expression increased in αSMA+ cells localized within the fibrotic region. Attenuation of COUP-TFII expression is associated with reduced expression of αSMA in pericyte-like cells. These data suggest that COUP-TFII may play a role in the regulation of pericyte-myofibroblast transdifferentiation in injury-induce kidney fibrosis.

Funding

  • Other NIH Support