Posttranscriptional down-regulation of small ribosomal subunit proteins correlates with reduction of 18S rRNA in RPS19 deficiency.

Ribosomal protein S19 (RPS19) is mutated in patients with Diamond-Blackfan anemia (DBA). We hypothesized that decreased levels of RPS19 lead to a coordinated down-regulation of other ribosomal (r-)proteins at the subunit level. We show that small interfering RNA (siRNA) knock-down of RPS19 results in a relative decrease of small subunit (SSU) r-proteins (S20, S21 and S24) when compared to large subunit (LSU) r-proteins (L3, L9, L30 and L38). This correlates with a relative decrease in 18S rRNA with respect to 28S rRNA. The r-protein mRNA levels remain relatively unchanged indicating a post transcriptional regulation of r-proteins at the level of subunit formation.