Vascular Smooth Muscle Cell-Specific Progerin Expression Provokes Contractile Impairment in a Mouse Model of Hutchinson-Gilford Progeria Syndrome that Is Ameliorated by Nitrite Treatment

Abstract

Cardiovascular disease (CVD) is the main cause of death worldwide, and aging is its leading risk factor. Aging is much accelerated in Hutchinson-Gilford progeria syndrome (HGPS), an ultra-rare genetic disorder provoked by the ubiquitous expression of a mutant protein called progerin. HGPS patients die in their teens, primarily due to cardiovascular complications. The primary causes of age-associated CVD are endothelial dysfunction and dysregulated vascular tone; however, their contribution to progerin-induced CVD remains poorly characterized. In the present study, we found that progeroid Lmna^G609G/G609G mice with ubiquitous progerin expression show both endothelial dysfunction and severe contractile impairment. To assess the relative contribution of specific vascular cell types to these anomalies, we examined Lmna^LCS/LCSTie2Cre^tg/+ and Lmna^LCS/LCSSm22αCre^tg/+ mice, which express progerin specifically in endothelial cells (ECs) and vascular smooth muscle cells (VSMCs), respectively. Whereas vessel contraction was impaired in mice with VSMC-specific progerin expression, we observed no endothelial dysfunction in mice with progerin expression restricted to VSMCs or ECs. Vascular tone regulation in progeroid mice was ameliorated by dietary sodium nitrite supplementation. Our results identify VSMCs as the main cell type causing contractile impairment in a mouse model of HGPS that is ameliorated by nitrite treatment.

Keywords: ECs; HGPS; VSMCs; progerin; sodium nitrite; vascular function.

Figure 1

Defective aortic contraction in Lmna^G609G/G609G mice. Thoracic aortas from 14-week-old progeroid Lmna^G609G/G609G mice (ubiquitous progerin expression) and wild-type (Lmna^+/+) mice were analyzed by wire myography (n = 12 for each genotype). (A) Strength of contraction induced by phenylephrine (left) and representation of the area under de curve (right; a.u.: arbitrary units). (B) Strength of contraction induced by KCl. Statistical differences were analyzed by two-way ANOVA with Bonferroni’s post-hoc test for phenylephrine data, and by two-tailed t-test for KCl data. * p < 0.05 *** p < 0.001.

Figure 2

Defective endothelium-dependent aortic dilation in Lmna^G609G/G609G mice. Thoracic aortas from 14-week-old progeroid Lmna^G609G/G609G mice (ubiquitous progerin expression) and wild-type mice (Lmna^+/+) were analyzed by wire myography (n = 12 for each genotype). (A) Endothelium-dependent vasodilation induced by acetylcholine (left) and representation of the area under the curve (AUC; a.u.: arbitrary units) (right). (B) Endothelium-independent vasodilation induced by the NO donor diethylamine NONOate (DEA-NO). (C) Representation of area under the curve from acetylcholine-dependent relaxation curves performed in the absence (control) or presence of L-NAME, tranylcypromine (TCP), catalase, or Tempol. Statistical differences were analyzed by two-way ANOVA with Bonferroni’s post-hoc test for acetylcholine and DEA-NO data, and by one-way ANOVA for AUC data. * p < 0.05 and ** p < 0.01 compared with corresponding control in (A) and (C); +, p < 0.05 Lmna^+/+ versus Lmna^G609G/G609G in (C).

Figure 3

Progerin expression restricted to VSMCs impairs aortic contraction, but VSMC-specific and EC-specific progerin expression is not sufficient to cause defective vessel relaxation. Wire myography was performed in thoracic aorta rings from 14-week-old mice expressing progerin specifically in VSMCs (Lmna^LCS/LCSSM22α^tg/+) or in ECs (Lmna^LCS/LCSTie2^tg/+) and in control mice without progerin expression (Lmna^LCS/LCS). (A) Contraction induced by phenylephrine (left) and KCl (right) in aortic rings from Lmna^LCS/LCSSM22α^tg/+ mice and Lmna^LCS/LCS controls. (B) Endothelium-dependent vasodilation induced by acetylcholine (left) and endothelium-independent vasodilation induced by diethylamine NONOate (DEA-NO) (right) in aortic rings from Lmna^LCS/LCSSM22α^tg/+ mice and Lmna^LCS/LCS controls. (C) Contraction induced by phenylephrine (left) and KCl (right) in aortic rings from Lmna^LCS/LCSTie2^tg/+ mice and Lmna^LCS/LCS controls. (D) Endothelium-dependent vasodilation induced by acetylcholine (left) and endothelium-independent vasodilation induced by DEA-NO (right) in aortic rings from Lmna^LCS/LCSTie2^tg/+ mice and Lmna^LCS/LCS controls. Statistical differences were analyzed by two-way ANOVA with Bonferroni’s post-hoc test for acethylcholine, DEA-NO, and phenylephrine data, and by two-tailed t-test for KCl data. * p < 0.05; *** p < 0.001.

Figure 4

Collagen disruption by collagenase does not rescue contractile impairment in progerin-expressing mice. Wire myography experiments to test the effect of 15 min incubation with 0.2% collagenase on contractile responses induced by 120 mM KCl in aortic rings. (A) Lmna^G609G/G609G mice and wild-type controls (Lmna^+/+). (B) Lmna^LCS/LCSSM22α^tg/+ mice and Lmna^LCS/LCS controls. Statistical differences were analyzed with two-way ANOVA followed by the Sidak multiple comparison test. * p < 0.05; *** p < 0.001.

Figure 5

Sodium nitrite treatment improves vascular tone regulation in progeroid mice. Wire myography in thoracic aorta rings from 14-week-old Lmna^G609G/G609G and wild-type mice (Lmna^+/+) treated with sodium nitrite in drinking water for 6 weeks. (A) Endothelium-dependent vasodilation induced by acetylcholine. (B) Endothelium-independent vasodilation induced by diethylamine NONOate (DEA-NO). (C) Contraction induced by phenylephrine. (D) Contraction induced by KCl. Statistical differences were analyzed by two-way ANOVA with Bonferroni’s post-hoc test for acetylcholine, DEA-NO and phenylephrine data, and by two-tailed t-test for KCl data. * p < 0.05.