Recapitulation of premature ageing with iPSCs from Hutchinson–Gilford progeria syndrome

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Abstract
The premature ageing disorder Hutchinson–Gilford progeria syndrome (HGPS) is a rare genetic condition characterized by a rapid onset of signs associated with normal ageing, such as atherosclerosis and the degeneration of vascular smooth-muscle cells. Liu et al. report that the altered structure of the nuclear envelope and epigenetic modifications that accumulate during physiological ageing or under specific disease conditions can be restored to normalcy by reprogramming somatic cell lines established with fibroblasts from patients with HGPS as induced pluripotent stem (iPS) cells. Directed differentiation of the resulting iPS cells as vascular smooth-muscle cells then leads to the appearance of the premature senescence phenotypes associated with vascular ageing. This HGPS iPS cell model provides a way to study the mechanisms regulating premature and normal ageing in vitro. Hutchinson–Gilford progeria syndrome (HGPS) is a rare and fatal human premature ageing disease1,2,3,4,5, characterized by premature arteriosclerosis and degeneration of vascular smooth muscle cells (SMCs)6,7,8. HGPS is caused by a single point mutation in the lamin A (LMNA) gene, resulting in the generation of progerin, a truncated splicing mutant of lamin A. Accumulation of progerin leads to various ageing-associated nuclear defects including disorganization of nuclear lamina and loss of heterochromatin9,10,11,12. Here we report the generation of induced pluripotent stem cells (iPSCs) from fibroblasts obtained from patients with HGPS. HGPS-iPSCs show absence of progerin, and more importantly, lack the nuclear envelope and epigenetic alterations normally associated with premature ageing. Upon differentiation of HGPS-iPSCs, progerin and its ageing-associated phenotypic consequences are restored. Specifically, directed differentiation of HGPS-iPSCs to SMCs leads to the appearance of premature senescence phenotypes associated with vascular ageing. Additionally, our studies identify DNA-dependent protein kinase catalytic subunit (DNAPKcs, also known as PRKDC) as a downstream target of progerin. The absence of nuclear DNAPK holoenzyme correlates with premature as well as physiological ageing. Because progerin also accumulates during physiological ageing6,12,13, our results provide an in vitro iPSC-based model to study the pathogenesis of human premature and physiological vascular ageing.