COPI vesicle formation and N-myristoylation are targetable vulnerabilities of senescent cells

Drugs that selectively kill senescent cells (senolytics) improve the outcomes of cancer, fibrosis and age-related diseases. Despite their potential, our knowledge of the molecular pathways that affect the survival of senescent cells is limited. To discover senolytic targets, we performed RNAi screens and identified coatomer complex I (COPI) vesicle formation as a liability of senescent cells. Genetic or pharmacological inhibition of COPI results in Golgi dispersal, dysfunctional autophagy, and unfolded protein response-dependent apoptosis of senescent cells, and knockdown of COPI subunits improves the outcomes of cancer and fibrosis in mouse models. Drugs targeting COPI have poor pharmacological properties, but we find that N-myristoyltransferase inhibitors (NMTi) phenocopy COPI inhibition and are potent senolytics. NMTi selectively eliminated senescent cells and improved outcomes in models of cancer and non-alcoholic steatohepatitis. Our results suggest that senescent cells rely on a hyperactive secretory apparatus and that inhibiting trafficking kills senescent cells with the potential to treat various senescence-associated diseases.

Galectin-1 prevents pathological vascular remodeling in atherosclerosis and abdominal aortic aneurysm

Pathological vascular remodeling is the underlying cause of atherosclerosis and abdominal aortic aneurysm (AAA). Here, we analyzed the role of galectin-1 (Gal-1), a β-galactoside-binding protein, as a therapeutic target for atherosclerosis and AAA. Mice lacking Gal-1 (Lgals1^-/-) developed severe atherosclerosis induced by pAAV/D377Y-mPCSK9 adenovirus and displayed higher lipid levels and lower expression of contractile markers of vascular smooth muscle cells (VSMCs) in plaques than wild-type mice. Proteomic analysis of Lgals1^-/- aortas showed changes in markers of VSMC phenotypic switch and altered composition of mitochondrial proteins. Mechanistically, Gal-1 silencing resulted in increased foam cell formation and mitochondrial dysfunction in VSMCs, while treatment with recombinant Gal-1 (rGal-1) prevented these effects. Furthermore, rGal-1 treatment attenuated atherosclerosis and elastase-induced AAA, leading to higher contractile VSMCs in aortic tissues. Gal-1 expression decreased in human atheroma and AAA compared to control tissue. Thus, Gal-1-driven circuits emerge as potential therapeutic strategies in atherosclerosis and AAA.

A major role of TWEAK/Fn14 axis as a therapeutic target for post-angioplasty restenosis

Background

Tumor necrosis factor-like weak inducer of apoptosis (Tnfsf12; TWEAK) and its receptor Fibroblast growth factor-inducible 14 (Tnfrsf12a; Fn14) participate in the inflammatory response associated with vascular remodeling. However, the functional effect of TWEAK on vascular smooth muscle cells (VSMCs) is not completely elucidated.

Methods

Next generation sequencing-based methods were performed to identify genes and pathways regulated by TWEAK in VSMCs. Flow-citometry, wound-healing scratch experiments and transwell migration assays were used to analyze VSMCs proliferation and migration. Mouse wire injury model was done to evaluate the role of TWEAK/Fn14 during neointimal hyperplasia.

Findings

TWEAK up-regulated 1611 and down-regulated 1091 genes in VSMCs. Using a gene-set enrichment method, we found a functional module involved in cell proliferation defined as the minimal network connecting top TWEAK up-regulated genes. In vitro experiments in wild-type or Tnfrsf12a deficient VSMCs demonstrated that TWEAK increased cell proliferation, VSMCs motility and migration. Mechanistically, TWEAK increased cyclins (cyclinD1), cyclin-dependent kinases (CDK4, CDK6) and decreased cyclin-dependent kinase inhibitors (p15^lNK4B) mRNA and protein expression. Downregulation of p15^INK4B induced by TWEAK was mediated by mitogen-activated protein kinase ERK and Akt activation.

Tnfrsf12a or Tnfsf12 genetic depletion and pharmacological intervention with TWEAK blocking antibody reduced neointimal formation, decreasing cell proliferation, cyclin D1 and CDK4/6 expression, and increasing p15^INK4B expression compared with wild type or IgG-treated mice in wire-injured femoral arteries. Finally, immunohistochemistry in human coronary arteries with stenosis or in-stent restenosis revealed high levels of Fn14, TWEAK and PCNA in VSMCs enriched areas of the neointima as compared with healthy coronary arteries.

Interpretation

Our data define a major role of TWEAK/Fn14 in the control of VSMCs proliferation and migration during neointimal hyperplasia after wire injury in mice, and identify TWEAK/Fn14 as a potential target for treating in-stent restenosis.

Fund

ISCiii-FEDER, CIBERCV and CIBERDEM.