Centromere protein J governs reproductive development and fertility in the silkworm Bombyx mori

Centromere protein J (CENPJ) is a core centrosomal protein essential for centriole duplication and microtubule organization, and mutations in the gene cause aberrant neuronal morphology and primary microcephaly in mammals. However, its functions in insect development remain poorly understood. In this study, we investigated the role of CENPJ in the silkworm Bombyx mori, a lepidopteran model featuring unique holocentric chromosomes. We found that CENPJ is evolutionarily conserved and predominantly expressed in silkworm gonads. Cellular assays demonstrated that CENPJ exhibits cytoplasmic localization and regulates cell proliferation and DNA replication. CRISPR-Cas9-mediated knockout of CENPJ caused almost sterility in both sexes, leading to severe defects in ovarian and testicular development, impaired formation of both eupyrene and apyrene sperm, and abnormal structures of the spermatheca and seminal vesicle. Transcriptional analysis revealed downregulation of genes involved in cell cycle and gonad development in mutant individuates. These findings establish CENPJ as a master regulator of insect reproductive development and highlight its potential as a molecular target for reproductive disruption in lepidopteran pest management.