Accumulation of mutant lamin A causes progressive changes in nuclear architecture in Hutchinson–Gilford progeria syndrome

TLDR

HGPS is a premature aging disorder caused by a lamin A point mutation that deletes 50 amino acids near the C‑terminus (LAΔ50). The study tests whether LAΔ50 induces nuclear structural changes through a concentration‑dependent dominant‑negative effect on lamin functions. The authors introduced LAΔ50 into normal cells via transfection or protein injection and used light and electron microscopy to assess nuclear morphology. Microscopy revealed that HGPS cells exhibit nuclear lobulation, lamina thickening, loss of peripheral heterochromatin, and nuclear pore clustering, which worsen with age and correlate with increased LAΔ50; introducing LAΔ50 into normal cells recapitulates these defects.

Abstract

Hutchinson–Gilford progeria syndrome (HGPS) is a premature aging disorder, commonly caused by a point mutation in the lamin A gene that results in a protein lacking 50 aa near the C terminus, denoted LAΔ50. Here we show by light and electron microscopy that HGPS is associated with significant changes in nuclear shape, including lobulation of the nuclear envelope, thickening of the nuclear lamina, loss of peripheral heterochromatin, and clustering of nuclear pores. These structural defects worsen as HGPS cells age in culture, and their severity correlates with an apparent increase in LAΔ50. Introduction of LAΔ50 into normal cells by transfection or protein injection induces the same changes. We hypothesize that these alterations in nuclear structure are due to a concentration-dependent dominant-negative effect of LAΔ50, leading to the disruption of lamin-related functions ranging from the maintenance of nuclear shape to regulation of gene expression and DNA replication.