Laminophatic Mutations Affect SUN-1 Dynamics and Chromosome Pairing During C. elegans Meiosis

During meiosis, homologous chromosomes undergo dynamic movements to ensure correct pairing. This process depends on the LINC complex, which transmits cytoskeletal forces across the nuclear envelope via SUN domain proteins anchored in the inner nuclear membrane. Here, we demonstrate that lamin plays an essential role at the nuclear periphery during early prophase I. Using Caenorhabditis elegans as a model, we introduced mutations into the Ig domain of the lamin gene (CeLMN) that mimic human laminopathic variants. These mutations impaired SUN-1 dynamics at the nuclear envelope, leading to defects in homologous chromosome pairing and synaptonemal complex assembly. Specifically, laminopathic strains displayed abnormal SUN-1 mobility, incomplete loading of the central element protein SYP-1, and altered localization of the axial element protein HTP-3. As a consequence, meiotic nuclei frequently contained supernumerary 4′,6-diamidino-2-phenylindole (DAPI)-stained bodies and exhibited chromosomal aberrations during diakinesis. Our findings reveal a crucial role for the lamin Ig domain in coordinating nuclear mechanics with LINC complex function, thereby safeguarding chromosome dynamics and genome stability during gametogenesis.