Laminopathy-inducing mutations reduce nuclear import of expressed prelamin A

作者：Kiel T; Busch A; Meyer Rachner A; Huebner S^*

来源：International Journal of Biochemistry & Cell Biology, 2014, 53: 271-280.

DOI：10.1016/j.biocel.2014.05.035

• Nuclear import
• NLS
• Laminopathies
• SSIM
• CaaX motif

Lamins are structural components of the nuclear lamina and integral parts of the nucleoplasm. The tripartite domain structure partitions the molecule into an amino-terminal head, central rod and a carboxy-terminal tail domain. The tail domain contains a nuclear localization sequence and in most lamins an additional CaaX motif, which is necessary to post-translationally process prelamin to mature lamin. As players of nuclear and cellular integrity, lamins must possess unrestrained access to the nucleus. To study whether nuclear trafficking of lamins is compromised in laminopathies, we determined relative nuclear import activities between expressed prelamin A and selected laminopathy-inducing mutants thereof. Furthermore, the impact of inhibition of maturation on nuclear import of expressed prelamin A was examined. To perform quantitative transport measurements, import competent but lamina incorporation-deficient GFP- or DsRed-tagged prelamin A deletion mutants were used, which lacked the head and rod domain (Delta HR-prelamin A). Nuclear accumulation of Delta HR-prelamin A carrying the lipodystrophy and metabolic syndrome-inducing mutations R419C and L421P or progeria-causing deletions was significantly reduced, but that of the maturation-deficient mutant Delta HR-prelamin A SSIM was significantly increased. In the case of the full length prelamin A mutants R419C and L421P altered subcellular localization and reduced lamina incorporation were detected, with the prelamin A-binding protein Narf being redistributed into R419-containing aggregates. The results suggest that impaired nuclear transport of certain prelamin A mutants may represent a contributing factor in the pathogenesis of certain laminopathies.

• 出版日期2014-8