ABSTRACT Lamins interact with the nuclear membrane and chromatin but the precise players and mechanisms of these interactions are unknown. Here, we tested whether the removal of the CaaX motif from Lamin B disrupts its attachment to the nuclear membrane and affects chromatin distribution. We used Drosophila melanogaster LamA25 homozygous mutants that lack the CaaX box. We found that the mutant Lamin B was not confined to the nuclear periphery but was distributed throughout the nuclear interior, colocalizing with chromosomes in salivary gland and proventriculus. The peripheral position of Lamin C, nuclear pore complex (NPC), heterochromatin protein 1a (HP1a), H3K9me2- and H3K27me3-associated chromatin remained intact. The fluorescence intensity of the DAPI-stained peripheral chromatin significantly decreased and that of the central chromatin significantly increased in the proventriculus nuclei of the mutantflies compared to wild-type. However, the mutation had little effect on chromatin radial distribution inside highly polytenized salivary gland nuclei.

中文翻译：

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缺乏 CaaX 盒的黑腹果蝇 Lamin B 突变体中核结构的重组

摘要 Lamins 与核膜和染色质相互作用，但这些相互作用的确切参与者和机制尚不清楚。在这里，我们测试了从 Lamin B 中去除 CaaX 基序是否会破坏其与核膜的附着并影响染色质分布。我们使用了缺乏 CaaX 框的黑腹果蝇 LamA25 纯合突变体。我们发现突变体 Lamin B 并不局限于核外围，而是分布在整个核内部，与唾液腺和腺胃中的染色体共定位。Lamin C、核孔复合物 (NPC)、异染色质蛋白 1a (HP1a)、H3K9me2 和 H3K27me3 相关染色质的外围位置保持完整。与野生型相比，DAPI 染色的外周染色质的荧光强度显着降低，而突变果蝇的腺胃核中的中央染色质的荧光强度显着增加。然而，该突变对高度聚合的唾液腺细胞核内的染色质径向分布几乎没有影响。