Premature aging disorders, metabolites, and atherosclerosis

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Project Summary/Abstract Premature senescence-triggered vascular diseases (PmSVD) induced by ionizing radiation (IR), as well as Hutchinson-Gilford progeria syndrome (HGPS), are notably characterized by accelerating processes of atherosclerosis (AthS) and coronary artery disease (CAD). Although endothelial dysfunction in PmSVDs is well known, there is a paucity of available treatments to prevent PmSVD-induced CAD; hence, there is an urgent need to fill this gap. Persistent senescence-associated secretory phenotype (PISP), provoked by TL dysfunction, plays a central role in cancer recurrence and resistance, but its regulatory mechanisms and contribution to AthS remain unknown. Our long-term goal is to determine the molecular mechanisms by which PmSVD induces PISP in endothelial cells (ECs) and CAD. PmSVD significantly up-regulated TOP2β degradation via PKCζ activation. The depletion of EC TOP2β instigated PARP activation and PISP; it also accelerated AthS. We showed the critical role of mtROS in PKCζ activation, which is one of the initial steps for the Mt-nucleus feedback loop. Of note, the crucial role of mtROS in both IR and HGPS has been well established. Lastly, by performing IC-MS analysis in both IR and HGPS ECs, we also found that the following 3 metabolite-related pathways were regulated in IR and HGPS ECs in common: 1) nucleotide sugars-glycosaminoglycans (GAGs) and sulfate, 2) glutamate, and 3) NAD+- hydrogen sulfide (H2S). Although the contribution of all 3 metabolites pathways to CAD and aging has been suggested, the exact role and mechanical insights in regulating PmSVD remain largely unknown. We propose the novel hypothesis that PmSVD-induced mtROS activates the PKCζ-TOP2β module, followed by TOP2β degradation, and instigates TL DNA damage. TL DNA damage promotes PARP activation, which induces mt dysfunction and forms an mt-nucleus feedback loop, resulting in persistent metabolites changes, including nucleotide sugars and NAD+-H2S pathways, causing PISP and CAD. We will test our hypothesis by pursuing the following 3 specific aims: In Aim 1, we will determine the role and regulatory mechanisms of the following 3 common metabolites-related pathways in PmSVD in vitro; 1) nucleotide sugars-GAGs and sulfate, 2) glutamate, 3) NAD+- H2S. in Aim 2, we will characterize the role of PKCζ-TOP2β module and PARP1 in PmSVD-mediated metabolites changes and mt dysfunction in vitro. In Aim 3, we will determine the role of the PKCζ-TOP2β module and subsequent PARP activation in PmSVD-induced coronary AthS (CAthS) in vivo. The proposed work is expected to establish the roles of PKCζ-TOP2β and PARP as the hub molecules in regulating PmSVD-induced metabolite changes and PISP. The approach is innovative because we will use the new technologies of iPSC, ion chromatography-mass spectrometry (IC-MS), machine learning, imaging mass cytometry, and a novel mouse CAthS model. The proposed research should positively impact PmSVD by leading to a novel approach to inhibiting PISP.