HECT domain and Ankyrin repeat-containing E3 ubiquitin protein ligase 1 (HACE1) is an E3 ubiquitin ligase involving oxidative stress, an important contributor in cerebral ischemia–reperfusion injury (CIRI). It was proposed to be associated with the PI3K/AKT pathway and Nrf2 nuclear translocation, which are important players of oxidative stress. Therefore, we supposed that HACE1 might affect CIRI by regulating the PI3K/AKT/Nrf2 pathway. Here, we used the transient middle cerebral artery occlusion-reperfusion (tMCAO/R) model to induce CIRI in rats and found lower HACE1 expression in ischemic rats compared with the control. To explore the exact role of HACE1, the lentivirus vector carrying the HACE1 sequence was administrated to rats by intracerebroventricular injection (1 × 10 9 TU/mL, 9 μL) one week before tMCAO/R operation. HACE1 overexpression alleviated tMCAO/R-induced brain damage in rats. Further studies revealed that it reduced oxidative stress via activating the PI3K/AKT/Nrf2 pathway, thereby inhibiting neuronal apoptosis in the ischemic penumbra of rats with CIRI. Then, differentiated PC12 cells were cultured in oxygen-glucose deprivation-reoxygenation (OGD/R) conditions (OGD: 1 % O 2 , 94 % N2, and 5 % CO 2 ; R: normal atmosphere) to simulate CIRI in vitro . Similarly, HACE1 overexpression inhibited neuronal apoptosis caused by OGD/R treatment. The PI3K inhibitor LY294002 reversed the inhibitory effects of HACE1 overexpression on oxidative stress in OGD/R-injured cells, accompanied by the inactivated AKT/Nrf2 pathway. Altogether, our results suggest that HACE1 protects against oxidative stress-induced neuronal apoptosis in CIRI by activating the PI3K/AKT/Nrf2 pathway, providing a new insight into the CIRI treatment.
Delong Meng,Qian Su,Kejuan Jia,Mengjie Jin,Wenting Liu,Shiqi Yang,Zhiqiang Su
Ischemic stroke is a kind of cerebrovascular disease with high mortality. The expression of ETS variant transcription factor 5 (ETV5) is down-regulated in ischemic stroke, but the specific role and mechanism remain unclear. In this study, the effects of ETV5 on ischemic stroke were investigated in vivo and in vitro by establishing the middle cerebral artery occlusion/reperfusion (MCAO/R) animal model and oxygen-glucose deprivation/reoxygenation (OGD/R) microglia model, respectively. We found that ETV5 reduced the infarct size, neurological deficit, microglia M1 polarization, and neuron pyroptosis level. Mechanistically, we further examined the expression of the HECT domain and ankyrin repeat-containing E3 ubiquitin protein ligase 1 (HACE1) and nuclear factor erythroid 2-related factor 2 (Nrf2) based on animal and cellular models to assess whether ETV5 affects ischemic stroke through the HACE1/Nrf2 signaling pathway. We found that ETV5 promoted the expression of HACE1 and Nrf2 in microglia and that HACE1 was transcriptionally activated by ETV5, which in turn competed with the E3 ligase KEAP1 for binding of Nrf2 and enhances the protein stability and nuclear expression of Nrf2. Our results suggest that ETV5 can ameliorate brain injury caused by ischemic stroke and this is closely related to inducing the HACE1/Nrf2 pathway to inhibit microglia M1 polarization.
Mingzhi Wu,Xiaojun Zhou,Xinyi Zhou,Genxin Wang,Yiqun Zeng,Jun Li,Edward V. Prochownik,Fubing Wang,Youjun Li
Cholesterol metabolism reprogramming plays essential roles in hepatocellular carcinoma (HCC). However, precisely how cholesterol metabolism is dysregulated is not clear. Here, we show that the palmitoyltransferase ZDHHC3 and depalmitoylase ABHD17A regulate HCC cell cholesterol biosynthesis by dynamically S-acylating SREBP cleavage-activating protein (SCAP). SCAP S-acylation by ZDHHC3 at C264 antagonizes HACE1-mediated SCAP ubiquitination. Intriguingly, SREBP2 transcriptionally upregulates ZDHHC3 to form a positive feedback loop, which explains why negative feedback regulation of SCAP/SREBP2 signaling fails in HCC. Increased cholesterol in the tumor microenvironment (TME) restrains CD4 + T cell cytotoxicity. Hence, the cholesterol metabolism reprogramming and cholesterol level alternation in the TME cooperate to promote HCC development. We identified a small-molecule inhibitor of ZDHHC3 that, combined with anti-PD-1 immunotherapy, inhibited diethyl nitrosamine (DEN)/CCl 4 -induced HCC growth in mice. ZDHHC3-mediated SCAP S-acylation reprograms cholesterol metabolism and promotes HCC immune escape. ZDHHC3 is thus identified as a rational chemotherapy target for HCC.
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