Ribonuclease Inhibitor and Angiogenin collaboratively regulate cell-type-specific global translation

Translation of mRNAs is a fundamental process that occurs in all cell-types of multicellular organisms. Conventionally, it has been considered a default step in gene expression, lacking specific regulation. However, recent studies have documented that certain mRNAs exhibit cell-type-specific translation1-3. Despite this, it remains unclear whether global translation is controlled in a cell-type-specific manner. Here we report that a ribosome-associated protein ribonuclease inhibitor-1 (RNH1) and its binding partner Angiogenin (ANG) collaboratively regulates cell-type-specific global translation. By employing human cell-lines and mouse models, we found that deletion of RNH1 decreases global translation selectively in hematopoietic origin cells but not in the non-hematopoietic origin cells. RNH1 mediated such cell-type-specific translation is mechanistically linked to ANG. We found that ANG, which is known to regulate ribosomal biogenesis4, is predominantly expressed in non-hematopoietic origin cells and absent in hematopoietic origin cells. ANG safeguards the non-hematopoietic origin cells from RNH1-knockout-mediated translation defects by upregulating ribosomal biogenesis. Further, we discovered that RNH1 controls the translation of ribosomal protein (RP) transcripts and influences mRNA circularization. Collectively, this study unravels the existence of cell-type-specific global translation regulators and highlights the complex translation regulation in vertebrates.