Human LMNA gene mutations result in laminopathies that include Emery-Dreifuss muscular dystrophy (AD-EDMD) and Hutchinson-Gilford progeria, the premature aging syndrome (HGPS). The Lmna null (Lmna−/−) and progeroid LmnaΔ9 mutant mice are models for AD-EDMD and HGPS, respectively. Both animals develop severe tissue pathologies with abbreviated life spans. Like HGPS cells, Lmna−/− and LmnaΔ9 fibroblasts have typically misshapen nuclei. Unexpectedly, Lmna−/− or LmnaΔ9 mice that are also deficient for the inner nuclear membrane protein Sun1 show markedly reduced tissue pathologies and enhanced longevity. Concordantly, reduction of SUN1 overaccumulation in LMNA mutant fibroblasts and in cells derived from HGPS patients corrected nuclear defects and cellular senescence. Collectively, these findings implicate Sun1 protein accumulation as a common pathogenic event in Lmna−/−, LmnaΔ9, and HGPS disorders.
Graphical Abstract
Highlights
▸ Premature death of progeric and dystrophic mice is ameliorated by removal of Sun1 ▸ LMNA mutations cause Sun1 overaccumulation in the Golgi ▸ Sun1 overaccumulation in the Golgi is pathogenic ▸ Cellular senescence of HGPS fibroblasts is corrected by depletion of SUN1