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Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)
 
 
 

Distinct functions for Ras GTPases in the control of proliferation and apoptosis in mouse and human mesangial cells.

In previous work, we have demonstrated that Ras GTPases regulate proliferation in a range of human renal cells. The present work compares human and mouse mesangial cell (HMC and MMC) responses to specific knockdown of Ras genes with antisense oligonucleotides (AS-oligos), and examines the role of the p21 ( cip1) and p27 (kip1) cyclin-dependent kinase inhibitors in these responses in mouse cells. HMC and MMC were lipofectin transfected with ras-targeted AS-oligo at 200-400 nM for 18 h followed by growth of cells in 20% serum for 18-72 h. Cell proliferation was assessed with an MTS assay and bromodeoxyuridine (BrdU) uptake. Apoptosis was quantified using nuclear stain with Hoechst 33342 dye. In MMC, Ha-ras AS-oligo caused an increase in apoptosis from <2% to 10-15% of cells after 18 h in serum (P<0.01). Control, Ki-ras and N-ras AS-oligos had minimal effects on apoptosis. BrdU uptake studies showed that BrdU+ve MMC were increased by 20-40% (P<0.05) after Ha-ras AS-oligo at 24 h; other ras AS-oligos were inactive. HMC number was reduced by 40-80% (P<0.01) at 48-72 h by both Ha-ras and Ki-ras AS-oligos. These actions were associated with reductions in BrdU+ve cells. In HMC, the ras AS-oligos did not induce apoptosis. p21(-,-) MMC showed exaggerated apoptotic responses to Ha-Ras AS-oligo. In mouse cells, Ha-Ras expression appears necessary to prevent apoptotic cell death; Ras expression does not appear necessary for cells to progress through the cell cycle. In human cells, Ras does not appear necessary to prevent apoptosis but Ha-Ras and Ki-Ras appear to be required for cell cycle progression.[1]

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