Masc‐induced dosage compensation in silkworm cultured cells

The Masculinizer (Masc) gene encodes a CCCH‐tandem zinc finger protein that controls both masculinization and dosage compensation in the silkworm Bombyx mori. We previously measured the masculinizing activity of the lepidopteran Masc proteins using B. mori ovary‐derived cell line BmN‐4. Here, we established an RNA‐seq data‐based assay system in which the level of B. mori Masc (BmMasc)‐induced dosage compensation can be estimated in BmN‐4 cells. Using this system, we found that a cysteine residue at position 301, which was shown to be essential for the masculinizing activity of BmMasc, is also required for dosage compensation. We further investigated the relationships between Masc‐induced cell growth inhibition, masculinizing activity, and the level of dosage compensation, using Masc genes from three lepidopteran insects. In summary, we have established a cell‐based system to monitor levels of Masc‐induced dosage compensation.