A snoRNA focused CRISPR-CAS9 screen identified SNORD42A to critically regulate proliferation of leukemic cells.
SNORD42A regulated ribosomal biogenesis and overall protein synthesis via 18S-U116 2´-O-methylation.
Non-coding RNAs including small nucleolar RNAs (snoRNAs) play important roles in leukemogenesis but the relevant mechanisms remain incompletely understood. We performed snoRNA focused CRISPR-Cas9 knockout library screenings which targeted the entire snoRNAnome and corresponding host genes. The C/D box containing SNORD42A was identified as an essential modulator for AML cell survival and proliferation in multiple human leukemia cell lines. In line, SNORD42A was consistently expressed at higher levels in primary AML patient samples than in CD34+ progenitors, monocytes and granulocytes. Functionally, knockout of SNORD42A reduced colony formation capability and inhibited proliferation. The SNORD42A acts as a C/D box snoRNA and directs 2´-O-methylation at Uridine 116 of 18S rRNA. Deletion of SNORD42A decreased 18S-U116 2´-O-methylation which was associated with a specific decrease in the translation of ribosomal proteins. In line, the cell size of SNORD42A deletion carrying leukemia cells was decreased. Taken together, these findings establish that high level expression of SNORD42A with concomitant U116 18S rRNA 2´-O-methylation is essential for leukemia cell growth and survival.