Geminin is essential for DNA re-replication in the silk gland cells of silkworms

Endoreplication, known as endocycles or endoreduplication, is a cell cycle variant in which the genomic DNA is re-replicated without mitosis leading to polyploidy. Endoreplication is essential for the development and func-tioning of the different organs in animals and plants. Deletion of Geminin, a DNA replication licensing inhibitor, causes DNA re-replication or damage. However, the role of Geminin in endoreplication is still unclear. Here, we studied the role of Geminin in the endoreplication of the silk gland cells of silkworms by constructing two transgenic silkworm strains, including BmGeminin1-overexpression and BmGeminin1-RNA interference. Inter-ference of BmGeminin1 led to body weight gain, increased silk gland volume, increased DNA content, and enhanced DNA re-replication activity relative to wild-type Dazao. Meanwhile, overexpression of BmGeminin1 showed an opposite phenotype compared to the BmGem1-RNAi strain. Furthermore, RNA-sequencing of the transgenic strains was carried out to explore how BmGeminin1 regulates DNA re-replication. Our data demon-strated a vital role of Geminin in the regulation of endoreplication in the silk gland of silkworms.

核内再复制，也称为核内周期或核内多倍化，是一种细胞周期变体，其中基因组DNA在无有丝分裂的情况下进行再次复制，从而导致多倍体。核内再复制对于动植物不同器官的发育和功能至关重要。Geminin是一种DNA复制许可抑制剂，其缺失会导致DNA再次复制或损伤。然而，Geminin在核内再复制中的作用仍不清楚。在此，我们通过构建两个转基因家蚕品系，包括BmGeminin1过表达和BmGeminin1 - RNA干扰，研究了Geminin在家蚕丝腺细胞核内再复制中的作用。与野生型大造相比，BmGeminin1的干扰导致体重增加、丝腺体积增大、DNA含量增加以及DNA再次复制活性增强。同时，BmGeminin1的过表达与BmGem1 - RNAi品系相比呈现出相反的表型。此外，对转基因品系进行了RNA测序，以探究BmGeminin1如何调控DNA再次复制。我们的数据表明了Geminin在家蚕丝腺核内再复制调控中的重要作用。