In vivo single-cell CRISPR screen for microproteins identifies a critical ribosome component

Here, we exploit an in vivo single-cell CRISPR screening strategy in the mouse epidermis to systematically investigate the tissue-wide function of microproteins. We document global and cell-type-specific roles of microproteins during epidermal development and homeostasis at single-cell transcriptomic resolution.

Focusing on select candidates, we identify a novel microprotein on Gm10076, identical to the ribosomal intersubunit bridge protein RPL41, whose perturbation strongly impairs proliferation and protein synthesis. Employing ribosome profiling and RNA sequencing, we show that Gm10076 perturbation profoundly reshapes the translational landscape. Contrary to its prior classification as nonessential, we find that the ribosomal protein RPL41 is critical for cellular proliferation, warranting further investigation into its role as an intersubunit bridge in the translational machinery.