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KRAB domain-associated protein 1 (KAP1) is highly expressed in atherosclerotic plaques. Here, we studied the role of KAP1 in atherosclerosis development using a cell model of endothelial dysfunction induced by oxidative low-density lipoprotein (OxLDL). The phosphorylation and protein levels of KAP1 were similar between OxLDL-treated and non-treated endothelial cells (ECs). KAP1 depletion significantly inhibited the production of OxLDL-enhanced reactive oxygen species and the expression of adhesion molecules in ECs. Treatment with OxLDL promoted the proliferation and migration of ECs, which was also confirmed by the elevated levels of the proliferative markers c-Myc and PCNA, as well as the migratory marker MMP-9. However, these effects were also abrogated by KAP1 depletion. Moreover, the depletion of KAP1 in OxLDL-treated ECs resulted in decreases in the LOX-1 level and increases in eNOS expression. Generally, the data suggest that strategies targeting KAP1 depletion might be particularly useful for the prevention or treatment of atherosclerosis.

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BackgroundNeural stem cell proliferation is a critical process in endogenous neurogenesis after ischemic/reperfusion injury. Ischemic succinate accumulation causes cerebral damage due to excess reactive oxygen species production. However, it remains elusive whether ischemic succinate accumulation affects neural stem cell proliferation.MethodsIn this study, we established rat middle cerebral artery occlusion model to mimic ischemic/reperfusion injury in vivo. Primary neural stem cell and neural stem cell line C17.2 were challenged with oxygen-glucose deprivation and reoxygenation. The level of succinate was assessed by liquid chromatography–mass spectrometry analysis. Cell proliferation was tested by cell counting kit 8. The infarct volume was measured by 2,3,5-Triphenyltetrazolium chloride staining. G protein coupled receptor GPR91 was detected by immunofluorescence. Sirtuin 5 knockdown was performed with Sirt 5 siRNA transfection. Cdc42 GTPase activity and succinylation were evaluated by co-immunoprecipitation.ResultsWe showed that succinate increased in the serum and brain (cortex and hippocampus) in middle cerebral artery occlusion rats. oxygen-glucose deprivation also induced abundant succinate in neural stem cell. Diethyl succinate inhibited C17.2 cell proliferation. Intraperitoneal administration of DS (800mg/kg) increased the infarct volume in middle cerebral artery occlusion rats. Besides, Diethyl succinate increases Cdc42 succinylation but represses Rho family GTPase Cdc42 activity, without affecting the level of its receptor G protein-coupled receptor-91 in neural stem cells. Increasing Cdc42 succinylation by desuccinylacylase Sirt5 knockdown inhibited GTPase Cdc42 activity. Accordingly, Cdc42 inhibtor ML141 also inhibited C17.2 proliferation.ConclusionsOur observations showed that accumulation of succinate inhibited neural stem cell proliferation by inducing Cdc42 succinylation, which reduced Cdc42 GTPase activity and was detrimental for neurogenesis after ischemic/reperfusion injury. Our data revealed a new mechanism that ischemic succinate accumulation aggrevated cerebral ischemic/reperfusion injury.