Figure 1.

Low translation levels in senescent cells are not due to global changes in mRNA abundance. (A) Young (Y) and senescent (S) WI-38 cells were labeled with L-[³⁵S]methionine and L-[³⁵S]cysteine for 15 min and whole-cell lysates were resolved by SDS-PAGE (12% polyacrylamide), transferred onto filters and visualized using a PhosphorImager. (B) Percentages of unchanged, upregulated and downregulated mRNAs in S relative to Y cells, as revealed by microarray analysis. (C) Partial list of genes identified by microarray analysis of Y and S cells; after isolation of total RNA, mRNAs were identified by Illumina microarray analysis. The threshold considered was ±2 fold. (D) Validation of expressed mRNAs by RT-qPCR amplification using gene-specific primer pairs. Transcript abundance was normalized to GAPDH mRNA.