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Published on: March 7, 2022
Targeted Activation of HNF4α by AMPK Inhibits Apoptosis and Ameliorates Neurological Injury Caused by Cardiac Arrest
Haohong Zhan1,2, Qiang Zhang3,2, Chenyu Zhang1,4,2
1Department of Emergency Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, China.
Abstract:
Previous studies have shown that AMPK plays an important role in cerebral ischemia-reperfusion injury by participating in apoptosis, but the exact mechanism and target of action remains unclear. This study aimed to investigate the protective mechanism of AMPK activation on brain injury secondary to cardiac arrest. HE, Nills and TUNEL assays were used to evaluate neuronal damage and apoptosis. The relationships between AMPK, HNF4α and apoptotic genes were verified by ChIP-seq, dual-luciferase and WB assays. The results showed that AMPK improved the 7-day memory function of rats, and reduced neuronal cell injury and apoptosis in the hippocampal CA1 region after ROSC, while the use of HNF4α inhibitor weakened the protective effect of AMPK. Further research found that AMPK positively regulated the expression of HNF4α, and AMPK could promote the expression of Bcl-2 and inhibit the expression of Bax and Cleaved-Caspase 3. In vitro experiments showed that AMPK ameliorated neuronal injury by inhibiting apoptosis through the activation of HNF4α. Combined with ChIP-seq, JASPAR analysis and Dual-luciferase assay, the binding site of HNF4α to the upstream promoter of Bcl-2 was found. Taken together, AMPK attenuates brain injury after CA by activating HNF4α to target Bcl-2 to inhibit apoptosis.
Insights
AMP-activated protein kinase (AMPK) activation protects the brain from cardiac arrest injury by reducing neuronal apoptosis. It achieves this by increasing HNF4α, which targets Bcl-2 to inhibit cell death.
Area of Science:
- Neuroscience
- Cellular Biology
- Biochemistry
Background:
- Cerebral ischemia-reperfusion injury involves apoptosis, with AMP-activated protein kinase (AMPK) playing a key role, though its precise mechanism is unclear.
- Understanding AMPK's protective mechanisms against brain injury following cardiac arrest (CA) is crucial for developing therapeutic strategies.
Purpose of the Study:
- To elucidate the protective mechanism of AMPK activation against brain injury after cardiac arrest (CA).
- To investigate the molecular targets and pathways through which AMPK exerts its neuroprotective effects.
Main Methods:
- Histological (HE, Nills) and TUNEL assays were used to assess neuronal damage and apoptosis.
- Chromatin immunoprecipitation sequencing (ChIP-seq), Western blot (WB), and dual-luciferase assays were employed to verify molecular interactions.
- In vivo (rat memory function, hippocampal CA1 region analysis) and in vitro experiments were conducted.
Main Results:
- AMPK activation improved memory function and reduced neuronal injury and apoptosis in the hippocampus post-ROSC.
- AMPK positively regulated hepatocyte nuclear factor 4-alpha (HNF4α) expression, which was essential for AMPK's protective effects.
- AMPK promoted Bcl-2 expression and inhibited Bax and Cleaved-Caspase 3, indicating apoptosis suppression via HNF4α targeting of Bcl-2.
Conclusions:
- AMPK activation attenuates brain injury following cardiac arrest by activating HNF4α.
- HNF4α, in turn, targets the Bcl-2 promoter to inhibit apoptosis, thereby conferring neuroprotection.
- This study reveals a novel AMPK-HNF4α-Bcl-2 pathway crucial for mitigating brain damage after CA.
