Abstract 12533: Progerin Causes a Disproportionate Senescence in Endothelial Cells

Abstract

Hutchinson-Gilford progeria syndrome (HGPS) is a premature aging disorder caused by the mutation of LMNA gene leading to irreversibly farnesylated lamin A protein, i.e. progerin. The major causes of death in HGPS are coronary and arterial occlusive disease. In the murine model of HGPS, vascular smooth muscle cells (VSMCs) loss is the primary vascular manifestation, which is quite different from the human arterial occlusive disease. To identify the mechanisms of HGPS vascular disease in humans, we differentiated isogenomic endothelial cells (ECs) and VSMCs from the same lines of HGPS-iPSCs and control-iPSCs. Both HGPS-ECs and HGPS-VSMCs manifested cellular hallmarks of aging, including dysmorphic nuclei, impaired proliferation, increased β-galactosidase staining, shortened telomeres, upregulated secretion of inflammatory cytokines, increased DNA damage, loss of heterochromatin and altered shelterin complex expression. However, at similar passage number, HGPS-ECs are more severely affected compared to VSMCs, as indicated by a higher percentage of β-galactosidase positive cells, significantly shortened telomere length, and greater frequency of DNA damage signals. With increasing passage number, there is progressive senescence in HGPS-ECs that is greater than that observed in HGPS-VSMCs. Using immunoprecipitation and mass spectrometry, we compared the integrity of the Shelterin Protein Complex (SPC), which is composed of six different proteins and whose function is to protect the telomeres, on the ECs and VSMCs of HGPS and control cells. We observed increased γH2A.X binding to RAP1 (member of SPC) and to Lamin A (nuclear envelope) in HGPS cells. The expression of γH2A.X was greater in HGPS ECs than VSMCs, and is associated with loss of SPC integrity, telomere shortening and loss of heterochromatin formation. Whereas progerin expression has deleterious effect in both vascular ECs and VSMCs, the severity of dysfunction is more extensive in HGPS-ECs in comparison to HGPS-VSMCs. These studies indicate that an endothelial-targeted therapy may be useful in HGPS.