AMPKα2 Knockout Exacerbates Hepatic Aging and Metabolic Dysfunction in Mice via Phosphoproteomic Changes
Background
The liver is highly susceptible to age-related changes, often leading to metabolic dysregulation and hepatic aging. Current interventions for age-related liver diseases are limited, highlighting a need for deeper mechanistic understanding. AMP-activated protein kinase α2 (AMPKα2) is a crucial regulator of cellular energy metabolism, playing a vital role in maintaining metabolic homeostasis. However, the specific effects of germline AMPKα2 knockout on the phosphoproteomic landscape of the aged liver, and how this contributes to age-related pathology, have remained largely unexplored, representing a significant gap in understanding its role in aging.
Study Design
This study investigated the impact of germline AMPKα2 knockout on aged mouse liver. Researchers utilized a mouse model lacking the AMPKα2 gene, comparing them to wild-type controls. The experimental approach involved comprehensive morphological analysis of liver tissue, Western blot (WB) to validate protein expression and phosphorylation states, and advanced data-independent acquisition (DIA) phosphoproteomic analysis. This phosphoproteomic approach was employed to identify and quantify site-specific phosphorylation changes across a wide range of proteins, providing a detailed molecular signature of the AMPKα2 knockout effect in the aged liver.
Results
The absence of AMPKα2 significantly exacerbated several hallmarks of hepatic aging. AMPKα2 knockout mice displayed worsened glucose-lipid metabolism dysfunction, heightened inflammatory responses, and pronounced age-related morphological changes in the liver. Enhanced senescent phenotypes were further validated by Western blot analysis. The DIA phosphoproteomic analysis identified a total of 4,448 specific phosphopeptides, with 316 of these showing significant differential modification between knockout and wild-type mice. Key findings included enhanced phosphorylation of glucose-lipid metabolism proteins: > Acetyl-CoA carboxylase 1 (Acaca) phosphorylation was significantly enhanced at S118, S80, S79, S157, and S117 sites in AMPKα2 knockout mice. Additionally, genomic instability protein HSP90β (Hsp90ab1) showed enhanced phosphorylation at S255. Conversely, phosphorylation of the stress response protein HSP27 (Hspb1) at S86 was significantly reduced, a finding independently validated by Western blot.
Key Findings
- Germline AMPKα2 knockout significantly worsened glucose-lipid metabolism dysfunction and inflammatory responses in aged mouse liver.
- Enhanced senescent phenotypes were observed and validated in AMPKα2 knockout aged mouse livers.
- Phosphoproteomic analysis identified 316 significantly differentially modified phosphopeptides in AMPKα2 knockout livers.
- Phosphorylation of
Acaca(glucose-lipid metabolism) was enhanced at multiple sites (e.g., S118, S80) in knockout mice. - Stress response protein
HSP27phosphorylation at S86 was significantly reduced in AMPKα2 knockout livers.
Why It Matters
This research provides a foundational phosphoproteomic map of the aged liver in the context of AMPKα2 deficiency, offering novel insights into the molecular mechanisms driving hepatic aging and metabolic dysfunction. For those interested in age-related diseases, this work highlights specific protein phosphorylation sites as potential therapeutic targets. Understanding how AMPKα2 modulates these phosphorylation events could lead to strategies for mitigating age-related liver damage. While this is a preclinical mouse study, the identification of HSP27 as a potential AMPKα2 downstream effector through site-specific phosphorylation opens avenues for drug development. This could eventually inform future protocols aimed at modulating AMPK activity or its downstream targets to combat liver aging and metabolic decline.
ampk
hepatic aging
metabolic dysfunction
phosphoproteomics
mouse model
inflammation