Epimedii Folium and Ligustri Lucidi Fructus synergistically delay renal aging through AMPK/ULK1/Bcl2L13-mediated mitophagy

Abstract

Ethnopharmacological relevance: The root of aging is attributed to kidney essence insufficiency and gradual loss of kidney function. The combination of Epimedii Folium and Ligustri Lucidi Fructus (ELL) is traditionally recognized to tonify kidney yin and yang and has significant efficacy in delaying aging and aging-related diseases, but little is known about the exact mechanism.

Aim of the study: The research focuses on the mechanism of delaying renal aging by which ELL regulates mitophagy through serine/threonine kinase AMP-activated protein kinase (AMPK)/UNC-51- like autophagy activating kinase 1 (ULK1)/B-cell lymphoma-2-like protein 13 (Bcl2L13) in vivo.

Materials and methods: We employed a rat model of natural aging, using rats of different ages as dynamic controls, and a natural aging mouse model to evaluate the effects of ELL on delaying renal aging via AMPK/ULK1/Bcl2L13. The assessment included renal histopathology, oxidative stress, cell senescence, mitochondrial dynamics, mitophagy, and the AMPK/ULK1/Bcl2L13 signaling pathway. In the aging rat model, network pharmacology and proteomics were combined to dissect the renal aging process, and a Multilayer Perceptron (MLP) -artificial neural networks (ANN) model was used to evaluate the effects of ELL comprehensively. In the aging mouse model, the AMPK inhibitor dorsomorphin was applied to assess whether the AMPK signaling pathway was involved in ELL-induced mitophagy.

Results: Compared with the young rats, the kidney exhibited signs of degenerative pathologies and increased oxidative stress in 17-month-old rats. A thorough analysis identified the mitochondrial protein Bcl2L13 as a crucial biomarker associated with renal aging. The AMPK/ULK1/Bcl2L13 pathway significantly regulated mitochondrial function and mitophagy, which were potential mechanisms underlying renal aging. In contrast to aged rats, the renal pathological changes and cell senescence in rats treated with ELL were significantly mitigated, the antioxidant capacity, mitochondrial dynamics, and mitophagy were improved, and the expression of AMPK/ULK1/Bcl2L13 was upregulated. After the application of AMPK inhibitor dorsomorphin, the effects of ELL were reversed. It appears that ELL modulates the AMPK/ULK1/Bcl2L13 signaling pathway, and upregulates mitophagy to potentially decelerate renal aging.

Conclusions: The findings indicate that aging kidneys display mitochondrial dysfunction, disorganization of mitochondria, and a decrease in mitophagy. Concurrently, ELL significantly regulates mitochondrial dynamics and mitophagy via AMPK/ULK1/Bcl2L13. This regulation helps mitigate mitochondrial dysfunction, suggesting ELL as a promising herbal remedy for delaying renal aging and age-related kidney diseases.

Keywords: AMPK/ULK1/Bcl2L13 signaling pathway; Epimedii folium/ligustri lucidi fructus; Mitophagy; Renal aging.