Cell-state- and compartment-dependent PI3K/Akt redox signaling in chronic kidney disease: mechanisms and...

Chronic kidney disease (CKD) progression results from coordinated pathological processes across diverse renal cell types and cannot be reduced to extracellular matrix accumulation alone. Tubular stress, disruption of the glomerular filtration barrier, microvascular rarefaction, immune activation, and interstitial remodeling collectively contribute to the progressive loss of renal structure and function. Although oxidative stress occurs throughout CKD progression, modern redox biology emphasizes that the effects of reactive oxygen species (ROS) depend on their source, concentration, chemical identity, duration, and subcellular localization. As a central hub in this redox regulatory network, the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) pathway integrates redox sensing with cell survival, metabolic reprogramming, inflammation, and fibrosis. In experimental systems, oxidative signals such as hydrogen peroxide (H₂O₂) can reversibly oxidize phosphatase and tensin homolog (PTEN) and other protein tyrosine phosphatases, thereby favoring localized phosphatidylinositol 3,4,5-trisphosphate (PIP3) accumulation and Akt activation. Activated Akt engages downstream effectors including nuclear factor erythroid 2-related factor 2 (Nrf2), forkhead box O (FOXO) transcription factors, mechanistic target of rapamycin (mTOR), glycogen synthase kinase 3 beta (GSK3β), nuclear factor kappa B (NF-κB), sterol regulatory element-binding proteins (SREBPs), autophagy-related pathways, and mitochondrial quality-control programs, thereby reshaping redox homeostasis and influencing injury and repair trajectories. PI3K/Akt signaling exhibits marked context dependence in CKD. The GSK3β/Nrf2 branch can enhance antioxidant defenses and limit inflammation, whereas sustained AKT serine/threonine kinase 1 (AKT1), mTOR complex 1 (mTORC1), mTOR complex 2 (mTORC2), or PI3K/Akt/mTOR/hexokinase II (HKII) signaling can promote maladaptive tubular repair, podocyte injury, and interstitial cell activation. PI3K/Akt therefore represents a key signaling node linking redox regulation, cell-state changes, and tissue remodeling. This review examines PI3K/Akt-mediated redox regulation across four dimensions: redox inputs, organellar microdomains, renal cell states, and clinical translation, while discussing therapeutic strategies tailored to specific cell states and spatial compartments.