Morrell, Craig

Introduction: Atherosclerotic lesions preferentially form in arterial regions exposed to disturbed flow (DF), where ECs exhibit mitochondrial (mt) dysfunction, metabolic reprogramming, and senescence. Hippo pathway kinases LATS1/2 maintain EC homeostasis, but how DF–mediated LATS1/2 suppression drives EC metabolic remodeling remains unclear. Hypothesis: We propose that DF activates CD38, leading to mt dysfunction and metabolic reprogramming that promotes EC senescence and aberrant proliferation by LATS1/2 inhibition. Methods: EC-specific Lats1/2 knockout mice were generated using tamoxifen-inducible Cre systems, and DF was induced by partial carotid ligation. Murine and human plaques were analyzed using COMET™ immunofluorescence, and spatial metabolomics. Bioenergetic profiling included Seahorse XF analysis, 13 C-glucose/ 13 C-glutamine tracing, and pharmacologic modulation of CD38, mtROS, and ATP synthase. Results: Complete Lats1/2 deletion caused fatal edema and vascular leakage, while partial loss produced fragile, highly neovascularized plaques. Spatial proteomics revealed a CD38-driven senescence-associated stemness (SAS) phenotype under LATS1/2 deficiency. Metabolomics showed sulfite and taurine accumulation, consistent with SUOX deficiency. Mechanistically, CD38 suppressed SUOX, induced Complex V reverse-mode , increased succinate flux, and accelerated ATP consumption. Despite ATP depletion, glutamate metabolism and TCA cycle flux were enhanced, sustaining EC proliferation under energetic stress. LATS1/2 knockdown reduced mt respiratory capacity (lower OCR peak) without significantly increasing glycolysis, and DF suppressed both OCR and ECAR, indicating impaired energy metabolism under pathological shear stress. CD38 inhibition restored mt respiration and glycolytic capacity by preserving NAD, and rescuing LATS1/2 and DF-mediated defects. Blocking reverse-mode Complex V reduced DF- and LATS1/2-dependent EC senescence and proliferation. Conclusion: Complete LATS1/2 deletion causes fatal vascular leakage, while partial loss drives plaque formation with fragile neovessels through a CD38-dependent SAS phenotype. CD38 suppresses SUOX, induces Complex V reverse-mode , increases succinate flux, and accelerates ATP consumption, enabling EC proliferation despite energy stress. DF and LATS1/2 loss impair mt and glycolytic function, whereas CD38 inhibition restores mt respiration and reduces EC senescence and proliferation to prevent atherothrombosis in DF regions.

BACKGROUND: Atherothrombosis, which underlies most acute coronary syndromes and is driven by intraplaque thrombosis, preferentially occurs in regions of disturbed blood flow (d-flow). Although LATS1/2 (large tumor suppressor kinases 1 and 2) are known regulators of endothelial mechanotransduction, the mechanisms by which d-flow connects endothelial senescence, proliferation, and intraplaque thrombosis remain poorly understood. METHODS: We investigated endothelial cell (EC)-specific roles of Lats1/2 using inducible EC-specific knockout mice in a partial carotid ligation model. Spatial multiomics of human and mouse plaques was performed using imaging mass cytometry, COMET sequential immunofluorescence, and spatial metabolomics. RESULTS: Tamoxifen-induced deletion of both Lats1 and Lats2 (homozygous) in ECs caused fatal edema and increased vascular permeability. In contrast, Lats1 het ( ± ) / Lats2 homo ( −/−) -EC-specific knockout mice survived and developed spontaneous atherothrombotic plaques with neovascularization. Spatial proteomics revealed that LATS1/2 loss induced a senescence-associated stemness phenotype driven by CD38 upregulation. Spatial metabolomics showed sulfite and taurine accumulation, indicating SUOX (sulfite oxidase) deficiency. CD38 suppressed SUOX, demonstrated a switch into the reverse mode of mitochondrial complex V, increased succinate dehydrogenase activity, and promoted ATP consumption. Despite ATP depletion, glutamate metabolism and the citric acid cycle flux increased, sustaining EC proliferation under energetic stress. This senescence-associated stemness state promoted both proliferation and senescence, leading to fragile, leaky neovessels and intraplaque thrombotic lesions. Pharmacological CD38 inhibition attenuated these phenotypes. Similar EC states were observed in human plaques. CONCLUSIONS: Loss of Lats1/2 in ECs induces a CD38-associated senescence-associated stemness-like phenotype that promotes intraplaque thrombosis through mitochondrial metabolic reprogramming, including changes consistent with reverse-mode operation of mitochondrial complex V. These findings define a mechanistic link between disturbed flow, endothelial metabolic reprogramming, and intraplaque thrombosis and hemorrhage.

Atherosclerotic and high-risk plaques are predominantly localized to vessel wall regions with non-laminar disturbed blood flow (d-flow), leading to the principle that d-flow-, but not laminar flow (l-flow)-driven endothelial cells (EC) dysfunction plays a role in this process. LATS1/2 and YAP are components of the Hippo signaling pathway that are involved in cellular responses to l-flow. The l-flow-mediated inhibition of LATS1/2 activity triggers YAP activation and maintains vascular structure. However, the role of Hippo signaling under d-flow remains unclear. Although both l- and d-flow increased YAP activity, only d-flow decreased LATS1/2 expression. Since the effects of l- and d-flow on EC differ, we studied the role of EC LATS1/2 using EC-specific Lats1 and 2 knock-out (EKO) mice. Within 14 days after inducing Lats1/2 deletion in tamoxifen-inducible Lats1 homo / Lats2 homo EKO mice, all the mice (27/27) died of severe systemic edema, accompanied by increased EC apoptosis and vascular permeability. We generated Lats1 he t / Lats2 homo -EKO mice ( Lats1 het /2 homo -EKO) and induced hypercholesteremia with AAV8-PCSK9 injections and a high-fat diet (HFD). After HFD, we detected plaque erosion-like plaque lesions at the d-flow areas, which revealed strongly fibrin/fibrinogen-positive organized thrombus (OTh) formation without sizeable necrotic cores. In Lats1 het /2 homo -EKO, we found significant increases in 1) EC proliferation, 2) EC apoptosis with senescent phenotype, 3) tissue factor (TF) expression, and 4) inflammation. Therefore, the phenotype observed in Lats1 het /2 homo -EKO represents a unique senescence-associated stemness (SAS) phenotype, which allows EC to escape senescence-induced cell cycle arrest. The EC proliferation induced by depletion of LATS1/2 was YAP-dependent. In contrast, EC senescence induced by CD38-mediated NAD + depletion was YAP-independent. These findings indicate that downregulating LATS1/2 expression-induced SAS leads to OTh via both YAP-dependent and independent mechanisms. OTh plays a key role in human atherosclerosis but is rarely observed in the mouse atherosclerosis model. Lats1 het /2 homo -EKO can provide a valuable platform for studying the mechanism and unique role of EC SAS-induced OTh formation.