p53 kinetics plays a key role in regulating cell fate.Based on the p53 gene regulatory network composed by the core regulatory factors ATM,Mdm2,Wipl,and PIDD,the effect of the delays in the process of transcription an...p53 kinetics plays a key role in regulating cell fate.Based on the p53 gene regulatory network composed by the core regulatory factors ATM,Mdm2,Wipl,and PIDD,the effect of the delays in the process of transcription and translation of Mdm2 and Wipl on the dynamics of p53 is studied theoretically and numerically.The results show that these two time delays can affect the stability of the positive equilibrium.With the increase of delays,the dynamics of p53 presents an oscillating state.Further,we also study the effects of PIDD and chemotherapeutic drug etoposide on the kinetics of p53.The model indicates that(i)PIDD low-level expression does not significantly affect p53 oscillatory behavior,but high-level expression could induce two-phase kinetics of p53;(ii)Too high and too low concentration of etoposide is not conducive to p53 oscillation.These results are in good agreement with experimental findings.Finally,we consider the infuence of internal noise on the system through Binomial r-leap algorithm.Stochastic simulations reveal that high-intensity noise completely destroys p53 dynamics in the deterministic model,whereas low-intensity noise does not alter p53 dynamics.Interestingly,for the stable focus,the internal noise with appropriate intensity can induce quasi-limit cycle oscillations of the system.Our work may provide the useful insights for the development of anticancer therapy.展开更多
Studies have shown that downregulation of nuclear-enriched autosomal transcript 1(Neat1)may adversely affect the recovery of nerve function and the increased loss of hippocampal neurons in mice.Whether Neat1 has prote...Studies have shown that downregulation of nuclear-enriched autosomal transcript 1(Neat1)may adversely affect the recovery of nerve function and the increased loss of hippocampal neurons in mice.Whether Neat1 has protective or inhibitory effects on neuronal cell apoptosis after secondary brain injury remains unclear.Therefore,the effects of Neat1 on neuronal apoptosis were observed.C57 BL/6 primary neurons were obtained from the cortices of newborn mice and cultured in vitro,and an oxygen and glucose deprivation cell model was established to simulate the secondary brain injury that occurs after traumatic brain injury in vitro.The level of Neat1 expression in neuronal cells was regulated by constructing a recombinant adenovirus to infect neurons,and the effects of Neat1 expression on neuronal apoptosis after oxygen and glucose deprivation were observed.The experiment was divided into four groups:the control group,without any treatment,received normal culture;the oxygen and glucose deprivation group were subjected to the oxygen and glucose deprivation model protocol;the Neat1 overexpression and Neat1 downregulation groups were treated with Neat1 expression intervention techniques and were subjected to the in oxygen and glucose deprivation protocol.The protein expression levels of neurons p53-induced death domain protein 1(PIDD1,a pro-apoptotic protein),caspase-2(an apoptotic priming protein),cytochrome C(a pro-apoptotic protein),and cleaved caspase-3(an apoptotic executive protein)were measured in each group using the western blot assay.To observe changes in the intracellular distribution of cytochrome C,the expression levels of cytochrome C in the cytoplasm and mitochondria of neurons from each group were detected by western blot assay.Differences in the cell viability and apoptosis rate between groups were detected by cell-counting kit 8 assay and terminal deoxynucleotidyl transferase dUTP nick-end labeling assay,respectively.The results showed that the apoptosis rate,PIDD1,caspase-2,and cleaved caspase-3 expression levels significantly decreased,and cell viability significantly improved in the Neat1 overexpression group compared with the oxygen and glucose deprivation group;however,Neat1 downregulation reversed these changes.Compared with the Neat1 downregulation group,the cytosolic cytochrome C level in the Neat1 overexpression group significantly decreased,and the mitochondrial cytochrome C level significantly increased.These data indicate that Neat1 upregulation can reduce the release of cytochrome C from the mitochondria to the cytoplasm by inhibiting the PIDD1-caspase-2 pathway,reducing the activation of caspase-3,and preventing neuronal apoptosis after oxygen and glucose deprivation,which might reduce secondary brain injury after traumatic brain injury.All experiments were approved by the Animal Ethics Committee of the First Affiliated Hospital of Chongqing Medical University,China,on December 19,2020(approval No.2020-895).展开更多
文摘p53 kinetics plays a key role in regulating cell fate.Based on the p53 gene regulatory network composed by the core regulatory factors ATM,Mdm2,Wipl,and PIDD,the effect of the delays in the process of transcription and translation of Mdm2 and Wipl on the dynamics of p53 is studied theoretically and numerically.The results show that these two time delays can affect the stability of the positive equilibrium.With the increase of delays,the dynamics of p53 presents an oscillating state.Further,we also study the effects of PIDD and chemotherapeutic drug etoposide on the kinetics of p53.The model indicates that(i)PIDD low-level expression does not significantly affect p53 oscillatory behavior,but high-level expression could induce two-phase kinetics of p53;(ii)Too high and too low concentration of etoposide is not conducive to p53 oscillation.These results are in good agreement with experimental findings.Finally,we consider the infuence of internal noise on the system through Binomial r-leap algorithm.Stochastic simulations reveal that high-intensity noise completely destroys p53 dynamics in the deterministic model,whereas low-intensity noise does not alter p53 dynamics.Interestingly,for the stable focus,the internal noise with appropriate intensity can induce quasi-limit cycle oscillations of the system.Our work may provide the useful insights for the development of anticancer therapy.
基金supported by the Youth Scienceof the National Natural Science Foundation of China,No.81701226(to LJ)。
文摘Studies have shown that downregulation of nuclear-enriched autosomal transcript 1(Neat1)may adversely affect the recovery of nerve function and the increased loss of hippocampal neurons in mice.Whether Neat1 has protective or inhibitory effects on neuronal cell apoptosis after secondary brain injury remains unclear.Therefore,the effects of Neat1 on neuronal apoptosis were observed.C57 BL/6 primary neurons were obtained from the cortices of newborn mice and cultured in vitro,and an oxygen and glucose deprivation cell model was established to simulate the secondary brain injury that occurs after traumatic brain injury in vitro.The level of Neat1 expression in neuronal cells was regulated by constructing a recombinant adenovirus to infect neurons,and the effects of Neat1 expression on neuronal apoptosis after oxygen and glucose deprivation were observed.The experiment was divided into four groups:the control group,without any treatment,received normal culture;the oxygen and glucose deprivation group were subjected to the oxygen and glucose deprivation model protocol;the Neat1 overexpression and Neat1 downregulation groups were treated with Neat1 expression intervention techniques and were subjected to the in oxygen and glucose deprivation protocol.The protein expression levels of neurons p53-induced death domain protein 1(PIDD1,a pro-apoptotic protein),caspase-2(an apoptotic priming protein),cytochrome C(a pro-apoptotic protein),and cleaved caspase-3(an apoptotic executive protein)were measured in each group using the western blot assay.To observe changes in the intracellular distribution of cytochrome C,the expression levels of cytochrome C in the cytoplasm and mitochondria of neurons from each group were detected by western blot assay.Differences in the cell viability and apoptosis rate between groups were detected by cell-counting kit 8 assay and terminal deoxynucleotidyl transferase dUTP nick-end labeling assay,respectively.The results showed that the apoptosis rate,PIDD1,caspase-2,and cleaved caspase-3 expression levels significantly decreased,and cell viability significantly improved in the Neat1 overexpression group compared with the oxygen and glucose deprivation group;however,Neat1 downregulation reversed these changes.Compared with the Neat1 downregulation group,the cytosolic cytochrome C level in the Neat1 overexpression group significantly decreased,and the mitochondrial cytochrome C level significantly increased.These data indicate that Neat1 upregulation can reduce the release of cytochrome C from the mitochondria to the cytoplasm by inhibiting the PIDD1-caspase-2 pathway,reducing the activation of caspase-3,and preventing neuronal apoptosis after oxygen and glucose deprivation,which might reduce secondary brain injury after traumatic brain injury.All experiments were approved by the Animal Ethics Committee of the First Affiliated Hospital of Chongqing Medical University,China,on December 19,2020(approval No.2020-895).
