A hallmark of meiosis is the precise pairing and the stable physical connection (synapsis) of the homologous chromosomes. These processes are essential prerequisite for their proper segregation. Pairing of the homologs during meiotic prophase I critically depends on characteristic movements of chromosomes. These movements, in turn, require attachment of meiotic telomeres to the nuclear envelope and their subsequent dynamic repositioning. Dynamic repositioning of meiotic telomeres goes along with profound structural reorganization of the nuclear envelope. The short A-type lamin C2 is thought to play a critical role in this process due to its specific expression during meiotic prophase I and the unique localization surrounding telomere attachments. Consistent with this notion, here we provide compelling evidence that meiosis-specific lamin C2 features a significantly increased mobility compared to somatic lamins as revealed by photobleaching techniques. We show that this property can be clearly ascribed to the lack of the N-terminal head and the significantly shorter α-helical coil domain. Moreover, expression of lamin C2 in somatic cells induces nuclear deformations and alters the distribution of the endogenous nuclear envelope proteins lamin B1, LAP2, SUN1 and SUN2. Together, our data define lamin C2 as a "natural lamin deletion mutant" that confers unique properties to the nuclear envelope which would be essential for dynamic telomere repositioning during meiotic prophase I.

中文翻译：

---

减数分裂特异性 lamin C2 的动态特性及其对核膜完整性的影响

减数分裂的一个标志是同源染色体的精确配对和稳定的物理连接（突触）。这些过程是它们正确分离的必要先决条件。减数分裂前期 I 期间同源物的配对主要取决于染色体的特征运动。反过来，这些运动需要减数分裂端粒附着在核膜上以及随后的动态重新定位。减数分裂端粒的动态重新定位伴随着核膜的深刻结构重组。短 A 型核纤层蛋白 C2 被认为在该过程中发挥关键作用，因为它在减数分裂前期 I 期间的特异性表达以及围绕端粒附件的独特定位。与这个观念一致，在这里，我们提供了令人信服的证据，表明与光漂白技术所揭示的体细胞 lamin 相比，减数分裂特异性 lamin C2 具有显着增加的流动性。我们表明，这种特性可以清楚地归因于缺乏 N 端头和明显更短的 α-螺旋线圈域。此外，体细胞中 lamin C2 的表达诱导核变形并改变内源性核膜蛋白 lamin B1、LAP2、SUN1 和 SUN2 的分布。总之，我们的数据将 lamin C2 定义为“天然 lamin 缺失突变体”，它赋予核膜独特的特性，这对于减数分裂前期 I 期间的动态端粒重新定位至关重要。我们表明，这种特性可以清楚地归因于缺乏 N 端头和明显更短的 α-螺旋线圈域。此外，体细胞中 lamin C2 的表达诱导核变形并改变内源性核膜蛋白 lamin B1、LAP2、SUN1 和 SUN2 的分布。总之，我们的数据将 lamin C2 定义为“天然 lamin 缺失突变体”，它赋予核膜独特的特性，这对于减数分裂前期 I 期间的动态端粒重新定位至关重要。我们表明，这种特性可以清楚地归因于缺乏 N 端头和明显更短的 α-螺旋线圈域。此外，体细胞中 lamin C2 的表达诱导核变形并改变内源性核膜蛋白 lamin B1、LAP2、SUN1 和 SUN2 的分布。总之，我们的数据将 lamin C2 定义为“天然 lamin 缺失突变体”，它赋予核膜独特的特性，这对于减数分裂前期 I 期间的动态端粒重新定位至关重要。