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Objective To analyze the influence of cyclic RNA homologous domain interacting protein kinase 3(circ_HIPK3)on function and morphology of myloid β-protein(Aβ)induced hippocampal neurons by targeting miR-381-3p/zinc finger protein 217(ZNF217)axis.Methods Hippocampal neurons of neonatal rats were prepared and divided into the control group,the Aβ group,the si NC1 group,the si HIPK3 group,the si HIPK3+inhibitor NC group,the si HIPK3+miR-381-3p inhibitor group,the si HIPK3+miR-381-3p inhibitor+si NC2 group and the si HIPK3+miR-381-3p inhibitor+si ZNF217 group.Except the control group,all the other groups were modeled by 40 μmol/L Aβ1～42.qRT-PCR was used to determine the circ of hippocampal neurons circ_HIPK3,miR-381-3p and ZNF217 mRNA levels.Cell morphology was observed by transmission electron microscope,and the survival rate of hippocampal neurons was measured by CCK-8 method.Hochesst 33342 method was used to measure apoptosis of hippocampal neurons.The intracellular Ca2+ fluorescence intensity of hippocampal neurons was detected by flow cytometry.The expression levels of P-Tau,B-cell lymphoma-2(Bcl-2),Bcl-2-associated X protein(Bax),Caspase-3 and ZNF217 proteins in hippocampal neurons were measured by Western blot assay.Double luciferase reporter genes were used to analyze the targeting relationship between miR-381-3p and circ_HIPK3,ZNF217.Results In the control group,the structure of hippocampal neurons was normal,the morphology of nucleus was normal,and there were no pathological changes in mitochondria and endoplasmic reticulum.In the Aβ group,hippocampal neurons showed degenerative changes,abnormal nuclear morphology,membrane invagination,a large number of mitochondria swelling and a large number of lipid droplets vacuoles in cytoplasm.Compared with the Aβ group,the hippocampal neuronal structure was partially restored in the si HIPK3 group.Compared with the si HIPK3 group,the hippocampal neuronal structure was severely damaged in the si HIPK3+miR-381-3p inhibitor group.Compared with the si HIPK3+miR-381-3p inhibitor group,the damage of hippocampal neurons in the si HIPK3+miR-381-3p inhibitor+si ZNF217 group was reduced.Compared with the control group,the circ_HIPK3,ZNF217 mRNA and ZNF217 protein levels,apoptosis rate,Ca2+ fluorescence intensity,P-Tau,Bax,Caspase-3 protein expression of hippocampal neurons were increased in the Aβ group,and the miR-381-3p level,survival rate and Bcl-2 protein expression decreased(P＜0.05).Compared with the Aβ group,the circ_HIPK3,ZNF217 mRNA and ZNF217 protein levels,apoptosis rate,Ca2+ fluorescence intensity,P-Tau,Bax and Caspase-3 protein expression of hippocampal neurons were decreased in the si HIPK3 group,and miR-381-3p level,survival rate and Bcl-2 protein expression increased(P＜0.05).Compared with the si HIPK3 group,the circ_HIPK3,ZNF217 mRNA and ZNF217 protein levels,apoptosis rate,Ca2+ fluorescence intensity,P-Tau,Bax and Caspase-3 protein expression of hippocampal neurons in the si HIPK3+miR-381-3p inhibitor group were increased,and the miR-381-3p level,survival rate and Bcl-2 protein expression decreased(P＜0.05).Compared with the si HIPK3+miR-381-3p inhibitor group,the ZNF217 mRNA and ZNF217 protein levels,apoptosis rate,Ca2+ fluorescence intensity,P-Tau,Bax and Caspase-3 protein expression of hippocampal neurons in the si HIPK3+miR-381-3p inhibitor+si ZNF217 group were decreased,and the survival rate and Bcl-2 protein expression increased(P＜0.05).miR-381-3p targeted and combined with HIPK3 and ZNF217.Conclusion circ_HIPK3 silencing may ameliorate Aβ-induced damage of hippocampal neuronal structure and function by regulating miR-381-3p/ZNF217 axis.
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Objective @#To investigate the relationship between circular RNA homeodomain interacting protein kinase 3 (circHIPK3) and the activation of rat microglia (RM) cells.@*Methods @#In vitro , RM cells were cultured and randomized into normal and oxygen⁃glucose deprivation/reperfusion (OGD/R) groups , and the expression level of circHIPK3 in each group was detected by RT⁃qPCR. The circHIPK3 lentiviral vector with puromycin resistance was constructed , and the overexpression (OE) group and negative control (NC) group were set up. The optimal multiplicity of infection (MOI) for RM cells was determined based on fluorescence expression , and puromycin was used to screen RM cells stably expressing circHIPK3. The cells of OE and NC groups were treated with OGD/R , and the expression levels of ionized calcium binding adaptor molecule 1 (Iba ⁃1) and eukaryotic tumor necrosis factor receptor superfamily (CD40) were detected by Western blot. The circHIPK3 translational protein potential was analyzed by the circRNAdb database , while the potential binding microRNAs on circHIPK3 were predicted by circBank and Starbase databases.@*Results @#OGD/R down⁃regulated circHIPK3 in RM cells ( P < 0. 000 1) . The sequencing results were accurate and the lentiviral vector of circHIPK3 was constructed successfully. The optimal MOI of RM cells was 80 , puromycin at a concentration of 2 μg/ml was used to screen RM cell lines stably expressing circHIPK3. RT⁃qPCR results showed that the expression level of circHIPK3 was significantly higher in the OE group compared with the NC group (P < 0. 01) . Western blot results revealed that the expression levels of Iba and CD40 in the OE group were markedly lower than those in the NC group (P < 0. 05) . Protein translation analysis showed that circHIPK3 encoded a polypeptide of 404 amino acids with two internal ribosome entry sites (IRES) and an open reading frame (ORF) . Database analysis uncovered that circHIPK3 could target eight specific miRNAs , namely hsa⁃miR⁃3529⁃5p , hsa⁃miR⁃379⁃5p , hsa⁃miR⁃506⁃3p , hsa⁃miR⁃33 , hsa⁃miR⁃450b⁃5p , hsa⁃miR551b⁃3p , hsa⁃miR⁃193 , and hsa⁃miR⁃508 ⁃3p.@*Conclusion @#The overexpression of circHIPK3 effectively suppresses OGD/R⁃induced activation of RM cells. It has the potential to encode peptides and may act as a miRNA sponge. These findings provide a foundation for further study of circHIPK3 functions.
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OBJECTIVE@#To investigate the effect and potential mechanism of dihydromyricetin (Dmy) on H9C2 cell proliferation, apoptosis, and autophagy.@*METHODS@#H9C2 cells were randomly divided into 7 groups, namely control, model, EV (empty pCDH-CMV-MCS-EF1-CopGFP-T2A-Puro vector), IV (circHIPK3 interference), Dmy (50 µ mol/L), Dmy+IV, and Dmy+EV groups. Cell proliferation and apoptosis were detected by cell counting kit-8 assay and flow cytometry, respectivley. Western blot was used to evaluate the levels of light chain 3 II/I (LC3II/I), phospho-phosphoinositide 3-kinase (p-PI3K), protein kinase B (p-AKT), and phospho-mammalian target of rapamycin (p-mTOR). The level of circHIPK3 was determined using reverse transcriptase polymerase chain reaction. Electron microscopy was used to observe autophagosomes in H9C2 cells.@*RESULTS@#Compared to H9C2 cells, the expression of circHIPK in H9C2 hypoxia model cells increased significantly (P<0.05). Compared to the control group, the cell apoptosis and autophagosomes increased, cell proliferation rate decreased significantly, and the expression of LC3 II/I significantly increased (all P<0.05). Compared to the model group, the rate of apoptosis and autophagosomes in IV, Dmy, and Dmy+IV group decreased, the cell proliferation rate increased, and the expression of LC3 II/I decreased significantly (all P<0.05). Compared to the control group, the expressions of p-PI3K, p-AKT, and p-mTOR in the model group significantly reduced (P<0.05), whereas after treatment with Dmy and sh-circHIPK3, the above situation was reversed (P<0.05).@*CONCLUSION@#Dmy plays a protective role in H9C2 cells by inhibiting circHIPK expression and cell apoptosis and autophagy, and the mechanism may be related to PI3K/AKT/mTOR pathway.