AMPK/PGC-1α and p53 modulate VDAC1 expression mediated by reduced ATP level and metabolic oxidative stress in neuronal cells

Abstract

Voltage-dependent anion channel 1 (VDAC1) is a pore protein located in the outer mitochondrial membrane. Its channel gating mediates mitochondrial respiration and cell metabolism, and it has been identified as a critical modulator of mitochondria-mediated apoptosis. In many diseases characterized by mitochondrial dysfunction, such as cancer and neurodegenerative diseases, VDAC1 is considered a promising potential therapeutic target. However, there is limited research on the regulatory factors involved in VDAC1 protein expression in both normal and pathological states. In this study, we find that VDAC1 protein expression is up-regulated in various neuronal cell lines in response to intracellular metabolic and oxidative stress. We further demonstrate that VDAC1 expression is modulated by intracellular ATP level. Through the use of pharmacological agonists and inhibitors and small interfering RNA (siRNA), we reveal that the AMPK/PGC-1α signaling pathway is involved in regulating VDAC1 expression. Additionally, based on bioinformatics predictions and biochemical verification, we identify p53 as a potential transcription factor that regulates VDAC1 promoter activity during metabolic oxidative stress. Our findings suggest that VDAC1 expression is regulated by the AMPK/PGC-1α and p53 pathways, which contributes to the maintenance of stress adaptation and apoptotic homeostasis in neuronal cells.

1. Introduction

Voltage-dependent anion channels (VDACs) are a family of transmembrane porins that are located mainly in the mitochondrial outer membrane and are described in eukaryotes of all species [1]. VDACs facilitate the transportation and mediation of ATP, metabolites, fatty acids, and ion fluxes across the mitochondrial outer membrane. As central regulators of mitochondrial cytoplasmic metabolic homeostasis and oxygen species (ROS)-induced apoptosis, VDACs play crucial roles in cellular processes [1,2]. VDACs also interact with various proteins from the cytoplasm, endoplasmic reticulum, and mitochondria, and participate in multiple signal transduction pathways. In addition, VDACs are critical proteins in mitochondria-mediated apoptosis and involve the release of apoptogenic factors and interaction with anti-apoptotic proteins [3].

In mammals, three isoforms of VDACs have been identified, namely, VDAC1, VDAC2, and VDAC3. These three isoforms are expressed in most tissues. Among them, VDAC1 is the most abundant and best characterized. The literature documents the significant upregulation of VDAC1 in cancer and neurodegenerative diseases, highlighting its potential as a pathological biomarker and therapeutic target [3–5]. However, the influencing factors involved in the transcription or expression mechanism of VDAC1 in higher eukaryotes remain to be determined. VDAC1 is encoded by nuclear genes, suggesting that its expression should be coordinated with that of other mitochondrial proteins to balance organelle biogenesis. The heterogeneous expression of VDAC isoforms suggests the presence of distinct regulatory mechanisms governing VDAC1 expression, in addition to overall gene regulation [6–8]. Since metabolic reprogramming and dysregulation of cellular redox status occur in both tumors and neurodegenerative diseases, we speculate that related signaling pathways and mechanisms may contribute to the regulation of VDAC1 expression.

Maintaining the balance between ATP production and ROS prevention is a key factor for the survival of neuronal cells. In the context of neurodegenerative diseases, impaired generation of energy and the burden of oxidative stress are substantial risk factors that underlie neuronal damage [9]. In neurocytomas, due to rapid growth and limited nutrient supply, cancer cells are often in a state of metabolic stress in the microenvironment [10]. Recent studies have indicated that metabolic stress initiates ROS-induced apoptosis and leads to increased expression of apoptosis-related proteins and transcription factors [11,12]. As a critical modulator of mitochondria-mediated apoptosis, VDAC1 expression may be regulated by molecular mechanisms related to neuronal metabolic disorders and oxidative stress. Notably, only a few studies have reported on potential transcription factors that are capable of modulating VDAC1 gene transcription activity. Previous studies via bioinformatics surveys and promoter activity experiments indicated that NRF-1 and HIF-1α are involved in the regulation of VDAC1 promoter activation, suggesting a potential regulatory mechanism of VDAC1 expression under nutrient deficiency and hypoxia [13].