LYC inhibits the AKT signaling pathway to activate autophagy and ameliorate TGFB-induced renal fibrosis

Renal fibrosis is a typical pathological change in chronic kidney disease (CKD). Epithelial-mesenchymal transition (EMT) is the predominant stage. Activation of macroautophagy/autophagy plays a crucial role in the process of EMT. Lycopene (LYC) is a highly antioxidant carotenoid with pharmacological effects such as anti-inflammation, anti-apoptosis and mediation of autophagy. In this study, we demonstrated the specific mechanism of LYC in activating mitophagy and improving renal fibrosis. The enrichment analysis results of GO and KEGG showed that LYC had high enrichment values with autophagy. In this study, we showed that LYC alleviated aristolochic acid I (AAI)-induced intracellular expression of PINK1, TGFB/TGF-β, p-SMAD2, p-SMAD3, and PRKN/Parkin, recruited expression of MAP1LC3/LC3-II and SQSTM1/p62, decreased mitochondrial membrane potential (MMP), and ameliorated renal fibrosis in mice. When we simultaneously intervened NRK52E cells using bafilomycin A₁ (Baf-A1), AAI, and LYC, intracellular MAP1LC3-II and SQSTM1 expression was significantly increased. A similar result was seen in renal tissue and cells when treated in vitro and in vivo with CQ, AAI, and LYC, and the inhibitory effect of LYC on the AAI-activated SMAD2-SMAD3 signaling pathway was attenuated. Molecular docking simulation experiments showed that LYC stably bound to the AKT active site. After intervention of cells with AAI and GSK-690693, the expression of PINK1, PRKN, MAP1LC3-II, BECN1, p-SMAD2 and p-SMAD3 was increased, and the expression of SQSTM1 was decreased. However, SC79 inhibited autophagy and reversed the inhibitory effect of LYC on EMT. The results showed that LYC could inhibit the AKT signaling pathway to activate mitophagy and reduce renal fibrosis.Abbreviation: AA: aristolochic acid; ACTA2/α-SMA: actin alpha 2, smooth muscle, aorta; ACTB: actin beta; AKT/protein kinase B: thymoma viral proto-oncogene; BAF-A1: bafilomycin A₁; BECN1: beclin 1, autophagy related; CCN2/CTGF: cellular communication network factor 2; CDH1/E-Cadherin: cadherin 1; CKD: chronic kidney disease; COL1: collagen, type I; COL3: collagen, type III; CQ: chloroquine; ECM: extracellular matrix; EMT: epithelial-mesenchymal transition; FN1: fibronectin 1; LYC: lycopene; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MMP: mitochondrial membrane potential; MTOR: mechanistic target of rapamycin kinase ; PI3K: phosphoinositide 3-kinase; PINK1: PTEN induced putative kinase 1; PRKN/Parkin: parkin RBR E3 ubiquitin protein ligase; PPI: protein-protein interaction; SMAD2: SMAD family member 2; SMAD3: SMAD family member 3; SQSTM1/p62: sequestosome 1; TGFB/TGFβ: transforming growth factor, beta; VIM: vimentin.