Biomedical Journal (Feb 2016)

Stimulation of transforming growth factor-beta-1 and contact with type I collagen cooperatively facilitate irreversible transdifferentiation in proximal tubular cells

  • Chieh-Li Yen,
  • Yi-Jung Li,
  • Hsin-Hsu Wu,
  • Cheng-Hao Weng,
  • Cheng-Chia Lee,
  • Yung-Chang Chen,
  • Ming-Yang Chang,
  • Tzung-Hai Yen,
  • Hsiang-Hao Hsu,
  • Cheng-Chieh Hung,
  • Chih-Wei Yang,
  • Ya-Chung Tian

DOI
https://doi.org/10.1016/j.bj.2015.08.004
Journal volume & issue
Vol. 39, no. 1
pp. 39 – 49

Abstract

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Background: By transdifferentiation, proximal tubular cells (PTC) have been considered as a source of interstitial myofibroblasts. We examined the combined effect of transforming growth factor-beta-1 (TGF-β1) stimulation and contact with type I collagen on PTC transdifferentiation. Methods: Human kidney-2 cells were grown on type I substratum with the concurrent stimulation of TGF-β1. Results: Following addition of TGF-β1, cells acquired an elongated fibroblastic appearance and an increase in α-smooth muscle actin (α-SMA) expression, a myofibroblastic marker. Upon addition of TGF-β1, E-cadherin expression, an epithelial marker, was reduced, while cytokeratin expression, another epithelial marker, remained unaltered. Following removal of TGF-β1, PTC regained an epithelial appearance and E-cadherin expression reverted to the unstimulated level, suggesting incomplete and reversible transdifferentiation. Addition of TGF-β1 to cells grown on type I collagen demonstrated a cooperatively increased α-SMA expression and decreased E-cadherin and cytokeratin expressions, suggesting more complete transdifferentiation. Co-stimulation of TGF-β1 and contact with type I collagen led to a stable cell phenotype and persistently decreased E-cadherin, which was not reversed upon removal of TGF-β1, indicating irreversible transdifferentiation. Addition of TGF-β1 or type I collagen caused a 4-fold increase in migratory cell number as compared to the control, whereas addition of both TGF-β1 and type I collagen led to an 11-fold increase. Conclusions: TGF-β1 alone results in a reversible and incomplete transdifferentiation. The combination of TGF-β1 and exposure to type I collagen leads to an irreversible and complete PTC transdifferentiation.

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