PGE2 causes mesangial cell hypertrophy and decreases expression of cyclin D3

Glomerular hypertrophy is a feature of many glomerular diseases and is associated with the development of renal failure. We previously demonstrated that the cyclooxygenase 2 inhibitor, NS398, reduced glomerular size after uninephrectomy. Thus, we hypothesized that prostaglandin (PG) E(2) would cause mesangial cell hypertrophy in vitro.

We used a mesangial cell line and primary culture of rat mesangial cells. The effects of PGE(2) on mesangial cell hypertrophy were determined using immunohistochemistry and image analysis to assess cell size, 3H-leucine incorporation as a measure of protein synthesis and flow cytometry to assess cell cycle status. Western blot was used to examine the effect of PGE(2) on expression of cyclin D3, p15, p27 and cyclin-dependent kinase 4--known regulators of the cell cycle.

PGE(2) increased cell size by 13% and protein synthesis (3H-leucine incorporation) by 35% over 24 h. By flow cytometry, PGE(2) increased the percentage of cells in G0/G1 phase of the cell cycle from 70.13 +/- 1.01 to 74.06 +/- 1.18% and conversely, decreased the number of cells in S phase from 24.07 +/- 1.06 to 22.03 +/- 0.78%. The number of cells in G2/M was also reduced. Expression of cyclin D3 was decreased by 60% after treatment with PGE(2), while expression of p27 was increased. The effects of PGE(2) on cell size and flow cytometry were reproduced by the prostaglandin E(2) receptors EP1/EP3 agonist sulprostone.

PGE(2) induces mesangial cell hypertrophy and cell cycle arrest via its EP1 receptor.