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Modeling Encephalopathy of Prematurity Using Prenatal Hypoxia-ischemia with Intra-amniotic Lipopolysaccharide in Rats
Published on: November 20, 2015
PHLDA1 contributes to hypoxic ischemic brain injury in neonatal rats via inhibiting FUNDC1-mediated mitophagy
Xiao-Lu Jiang1,2,3, Zu-Bin Zhang4,5, Chen-Xi Feng1
1Pediatrics Research Institute, Children's Hospital of Soochow University, Suzhou, 215025, China.
Insights
Pleckstrin homology-like domain family A member 1 (PHLDA1) exacerbates neonatal brain injury after hypoxia-ischemia (HI). PHLDA1 inhibits mitophagy, worsening neuronal damage, while its knockdown offers neuroprotection.
Area of Science:
- Neuroscience
- Cell Biology
- Pathology
Background:
- Neonatal brain injury is frequently caused by hypoxia-ischemia (HI).
- Mitophagy, the process of degrading damaged mitochondria, is crucial for cell survival following HI.
- Pleckstrin homology-like domain family A member 1 (PHLDA1) is involved in cellular processes like apoptosis and oxidative stress.
Purpose of the Study:
- To investigate the role of PHLDA1 in hypoxia-ischemia (HI)-induced neuronal injury in neonates.
- To explore the mechanisms by which PHLDA1 regulates mitophagy in the context of neonatal brain injury.
Main Methods:
- Established a hypoxia-ischemia (HI) model in newborn rats.
- Utilized primary hippocampal neurons subjected to oxygen and glucose deprivation/reoxygenation (OGD/R) in vitro.
- Employed lentiviral vectors for PHLDA1 knockdown and overexpression, and utilized mitophagy inhibitor Mdivi-1 and FUNDC1 knockdown.
Main Results:
- PHLDA1 expression was significantly upregulated in HI-induced neonatal brain injury models and OGD/R-treated neurons.
- PHLDA1 knockdown ameliorated neuronal injury and improved cognitive function in HI rats, while overexpression worsened outcomes.
- PHLDA1 knockdown enhanced mitophagy by activating FUNDC1, which was essential for its neuroprotective effects.
Conclusions:
- PHLDA1 plays a detrimental role in neonatal hypoxia-ischemia (HI) brain injury.
- PHLDA1 contributes to injury by inhibiting FUNDC1-mediated mitophagy.
- Targeting PHLDA1 may offer a therapeutic strategy for neonatal brain injury.
Abstract:
Hypoxia-ischemia (HI) is one of the main causes of neonatal brain injury. Mitophagy has been implicated in the degradation of damaged mitochondria and cell survival following neonatal brain HI injury. Pleckstrin homology-like domain family A member 1 (PHLDA1) plays vital roles in the progression of various disorders including the regulation of oxidative stress, the immune responses and apoptosis. In the present study we investigated the role of PHLDA1 in HI-induced neuronal injury and further explored the mechanisms underlying PHLDA1-regulated mitophagy in vivo and in vitro. HI model was established in newborn rats by ligation of the left common carotid artery plus exposure to an oxygen-deficient chamber with 8% O2 and 92% N2. In vitro studies were conducted in primary hippocampal neurons subjected to oxygen and glucose deprivation/-reoxygenation (OGD/R). We showed that the expression of PHLDA1 was significantly upregulated in the hippocampus of HI newborn rats and in OGD/R-treated primary neurons. Knockdown of PHLDA1 in neonatal rats via lentiviral vector not only significantly ameliorated HI-induced hippocampal neuronal injury but also markedly improved long-term cognitive function outcomes, whereas overexpression of PHLDA1 in neonatal rats via lentiviral vector aggravated these outcomes. PHLDA1 knockdown in primary neurons significantly reversed the reduction of cell viability and increase in intracellular reactive oxygen species (ROS) levels, and attenuated OGD-induced mitochondrial dysfunction, whereas overexpression of PHLDA1 decreased these parameters. In OGD/R-treated primary hippocampal neurons, we revealed that PHLDA1 knockdown enhanced mitophagy by activating FUNDC1, which was abolished by FUNDC1 knockdown or pretreatment with mitophagy inhibitor Mdivi-1 (25 μM). Notably, pretreatment with Mdivi-1 or the knockdown of FUNDC1 not only increased brain infarct volume, but also abolished the neuroprotective effect of PHLDA1 knockdown in HI newborn rats. Together, these results demonstrate that PHLDA1 contributes to neonatal HI-induced brain injury via inhibition of FUNDC1-mediated neuronal mitophagy.
