Angiotensin II-stimulated hypertrophy of LLC-PK1 cells depends on the induction of the cyclin-dependent kinase inhibitor p27Kip1

Kidney Int. 1996 Dec;50(6):2112-9. doi: 10.1038/ki.1996.537.


Angiotensin II (Ang II) induces hypertrophy of cultured proximal tubular epithelial cells including the LLC-PK1 cell line. We have previously shown that this hypertrophy appears in the G1-phase of the cell cycle. Since progression through the cell cycle is controlled by a series of cyclin and cyclin-dependent kinase (CdK) complexes that may be inactivated by CdK inhibitors, we studied the expression of the CdK-inhibitor p27Kip1 in LLC-PK1 cells challenged with Ang II. Compared to cells grown in serum-free medium, Ang II treatment enhanced p27Kip1 protein, but not mRNA expression. This p27Kip1 induction was mediated through AT1-receptors. Exogenous TGF-beta also stimulated p27Kip1 protein expression. Immunoprecipitation experiments revealed that p27Kip1 preferentially associated with CdK4 in Ang II-treated LLC-PK1 cells and that the activity of this kinase was inhibited after Ang II-treatment, an effect that may be generated by increased p27Kip1 binding to cyclin D1-CdK4 complexes. In contrast, p27Kip1 was not associated with cyclin E-CdK2 complexes in Ang II-stimulated cells. Treatment of LLC-PK1 cells with p27Kip1 antisense, but not missense, oligonucleotides abolished the Ang II-mediated cell hypertrophy as measured by de novo protein synthesis and total protein content, and facilitated entry into the S-phase of the cell cycle. Our findings suggest that Ang II stimulates p27Kip1 expression in renal cells. Furthermore, this induction of the CdK-inhibitor appears pivotal in the hypertrophy induced by Ang II and elucidates the molecular mechanisms associated with this growth response in proximal tubular cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Angiotensin II / toxicity*
  • Animals
  • Cell Cycle Proteins*
  • Cyclin-Dependent Kinase Inhibitor p27
  • Cyclin-Dependent Kinases / antagonists & inhibitors*
  • G1 Phase
  • Hypertrophy
  • Kidney Tubules, Proximal / drug effects
  • Kidney Tubules, Proximal / pathology*
  • LLC-PK1 Cells
  • Microtubule-Associated Proteins / physiology*
  • Swine
  • Tumor Suppressor Proteins*


  • Cell Cycle Proteins
  • Microtubule-Associated Proteins
  • Tumor Suppressor Proteins
  • Angiotensin II
  • Cyclin-Dependent Kinase Inhibitor p27
  • Cyclin-Dependent Kinases