ABSTRACT
Autophagy is implicated in the pathogenesis of pulmonary arterial hypertension (PAH). We aimed to investigate whether the p62-Keap1-Nrf2 pathway affects the development of PAH by mediating autophagy. A PAH rat model was established using monocrotaline (MCT). Pulmonary artery smooth muscle cells (PASMCs) were extracted, and the changes in proliferation, migration, autophagy, and oxidative stress were analyzed following overexpression or knockdown of p62. The impact of p62 on the symptoms of PAH rats was assessed by the injection of an adenovirus overexpressing p62. We found that the knockdown of p62 increased the proliferation and migration of PASMCs, elevating the oxidative stress of PASMCs and upregulating gene expression of NADPH oxidases. Co-IP assay results demonstrated that p62 interacted with Keap1. p62 knockdown enhanced Keap1 protein stability and Nrf2 ubiquitination. LC3II/I and ATG5 were expressed more often when p62 was knocked down. Treating with an inhibitor of autophagy reversed the impact of p62 knockdown on PASMCs. Nrf2 inhibitor treatment reduced the expression of Nrf2 and p62, while increasing the expression of Keap1, LC3II/I, and ATG5 in PASMCs. However, overexpressing p62 diminished mRVP, SPAP, and Fulton index in PAH rats and attenuated pulmonary vascular wall thickening. Overexpression of p62 also decreased the expression of Keap1, LC3II/I, and ATG5 and increased the nuclear expression of Nrf2 in PAH rats. Importantly, overexpression of p62 reduced oxidative stress and the NADPH oxidase expression in PAH rats. Overall, activation of the p62-Keap1-Nrf2 positive feedback signaling axis reduces the proliferation and migration of PASMCs and alleviates PAH by inhibiting autophagy and oxidative stress.
Subject(s)
Pulmonary Arterial Hypertension , Animals , Rats , Autophagy/physiology , Cell Proliferation , Kelch-Like ECH-Associated Protein 1/genetics , Kelch-Like ECH-Associated Protein 1/metabolism , Monocrotaline , Myocytes, Smooth Muscle/metabolism , NF-E2-Related Factor 2/genetics , NF-E2-Related Factor 2/metabolism , Pulmonary Arterial Hypertension/pathology , Pulmonary Artery/metabolismABSTRACT
OBJECTIVE: To investigate the effect of ligustilide (LIG) on low potassium-induced apoptosis in primary cultured cerebellar granule neurons (CGN). METHODS: Apoptosis was induced by low potassium in cultured neonatal rat CGN in vitro. The CGN was divided into control/model/CGP54626 + LIG and LIG group. The neuronal viability of each group was measured by MTT assay. The protein expression levels of the key insulin-like growth factor 1 (IGF)-1 signaling effectors,including the phosphorylated IGF-1 receptor (IGF-1R), Akt, ERK1/2, CREB and activated caspase 3 were examined by Western blot analysis. RESULTS: LIG ranging from 2.5 to 20 micromol/L could protect against low potassium-induced apoptosis of CGN ini a concentration-dependent manner. 20 micromol/L LIG significantly induced upregulation of the phosphorylated levels of IGF-1, Akt, ERK1/2 and CREB, and downregulation of cleaved-caspase 3 expression, which could be blocked by a selective gamma-aminobutyric acid B (GABAs) receptor antagonist CGP54626. CONCLUSION: LIG concentration-dependently protects against low potassium-induced apoptosis in CGN at least partly through GABAa receptor activation and its downstream IGF-1 signaling pathway.
Subject(s)
4-Butyrolactone/analogs & derivatives , Apoptosis/drug effects , Neurons/drug effects , Potassium , Signal Transduction , 4-Butyrolactone/pharmacology , Animals , Animals, Newborn , Caspase 3/metabolism , Cells, Cultured , Cerebellum/cytology , Insulin-Like Growth Factor I/metabolism , Neurons/cytology , Organophosphorus Compounds , Phosphorylation , Rats , Receptor, IGF Type 1/metabolismABSTRACT
Klotho, an aging-suppressor gene, encodes a protein that potentially acts as a neuroprotective factor by modulating insulin-like growth factor 1 signaling and oxidative stress. In the present study, we investigated the potential role of Klotho in the therapeutic effect of ligustilide against Alzheimer's disease (AD)-like neuropathologies and memory impairment in aged senescence-accelerated mouse prone-8 (SAMP8) mice. Ligustilide treatment (10 and 40 mg/kg for 8 weeks, intragastrically) in 10-month-old SAMP8 mice reduced memory deficits, amyloid-ß(1)-42 accumulation, tau phosphorylation, and neuron loss, increased mitochondrial manganese-superoxide dismutase and catalase expression and activity, and decreased malondialdehyde, protein carbonyl, and 8-hydroxydesoxyguanosine levels in the brain. Ligustilide upregulated Klotho expression in the cerebral choroid plexus and serum, decreased Akt and Forkhead box class O1 phosphorylation. Moreover, ligustilide inhibited the insulin-like growth factor 1 pathway and induced Forkhead box class O1 activation in 293T cells along with Klotho upregulation. An inverse correlation was found between Klotho expression and the AD phenotype, suggesting that Klotho might be a novel therapeutic target for age-related AD, and Klotho upregulation might contribute to the neuroprotective effect of ligustilide against AD.
