Abstract We0064: PSMD7 regulates the stability of TFEB protein and participates in atherosclerosis

Background: Atherosclerosis (AS) is an important cause of cardiovascular and cerebrovascular diseases. Inflammation and autophagy play important roles in the occurrence and progression of AS. The transcription factor EB (TFEB) has been shown to inhibit inflammation and promote autophagy, thereby alleviating the development of AS. Proteasome 26S subunit, non-ATPase 7 (PSMD7) is an important component of the proteasome deubiquitinating enzyme complex, and its role in the progression of AS has not been reported. Methods: The relationship between PSMD7 protein expression and prognosis was analyzed by collecting the plaque tissues of 20 patients who underwent CEA.The expression of PSMD7 in AS was detected by Western-blot and immunohistochemistry. Searching for PSMD7 interacting proteins in PSMD7 knockdown endothelial cells by Mass spectrum. Immunofluorescence, co-immunoprecipitation (CO-IP), proximity ligation assay (PLA), and GST pull-down experiments were performed to confirm the interaction between PSMD7 and TFEB, and their co-localization in the proteasome. The effect of PSMD7 on the stability of TFEB protein was detected by protein stability assay. In vitro experiments were conducted to determine if PSMD7 can remove the ubiquitination of TFEB. Furthermore, the regulatory effects of PSMD7 on inflammation and autophagy were evaluated by manipulating PSMD7 expression in TFEB wild-type and knockout vascular endothelial cells. Animal studies using apolipoprotein E gene knockout (ApoE -/- ) mice were also conducted to assess the impact of PSMD7 modulation on plaque stability and AS progression. Results: PSMD7 is highly expressed in AS tissues. PSMD7 and TFEB were co-located in vascular endothelial cells. CO-IP and GST-pull down experiments show that PSMD7 and TFEB have direct interaction. Knockdown of PSMD7 enhanced TFEB stability by preventing its ubiquitination and subsequent proteasomal degradation. This stabilization of TFEB led to increased transcription of autophagy-related genes and reduced the expression of pro-inflammatory adhesion molecules in endothelial cells. In ApoE -/- mice, inhibition of PSMD7 resulted in enhanced plaque stability and delayed AS progression, whereas endothelial-specific overexpression of PSMD7 accelerated AS development. Conclusion: PSMD7 directly binds to TFEB, promoting its ubiquitination and proteasomal degradation, inhibiting TFEB-mediated autophagy, and enhancing inflammatory responses, thereby promoting the progression of AS.