Study On The Correlation Between PTEN Gene And Axon Regeneration Of IB4~+ Neuron

Part Ⅰ Expression of PTEN gene association with axon regeneration of IB4~+ neuronPurpose:Injured nerve regeneration is a major clinical problem,because of the poor functional recovery,high propotion of disability.In peripheral nervous system(PNS),the axons of Isolectin B4 positive(IB4~+)neurons can hardly regenerate after injury.Previous studies found that PTEN gene widely expressed in nervous system,inhibition of PTEN gene promoted axon regeneration in central nervous system(CNS).So,we purpose that PTEN gene expression in IB4~+ neurons is correlated with the poor axon regeneration ability of IB4~+ neurons.Methods:In this study,we harvest dorsal root ganglion cells(DRGs)for culture from ICR mice with or without sciatic nerve axotomy respectively,the length of axons in IB4~+ and IB4-neurons were measured.DRG tissures were cryo-sectioned and immunostained to examine the distribution and expression of PTEN gene in IB4~+ and IB4-neurons.The changes of PTEN gene expression before and after sciatic nerve axotomy in IB4~+ neurons were also observed.Results: Whethter DRGs cultured with or without sciatic nerve axotomy,axon length of IB4~+ neurons is much more shorter than IB4-neurons(p<0.05);Immunostaining results of DRG tissues showed that PTEN expression in IB4~+ neurons is higher than in IB4-neurons,and the expression of PTEN gene was not significantly decreased after sciatic nerve axotomy.Conclusion:The ability of axon regeneration in IB4~+ neurons is much more weaken than IB4-neurons.PTEN gene expression in IB4~+ neurons is higher than in IB4-neurons and the expression of PTEN gene in IB4~+ neurons is not significantly decreased after sciatic nerve axotomy.Part Ⅱ Inhibition of PTEN gene promotes axonal regeneration of IB4~+ neuronsPurpose:The ability of axon regeneration in peripheral nerve is poor,especially in the IB4~+ neurons.Previous studies showed that inhibition of PTEN gene promotes axon regeneration in CNS.Besides,our results in the first part showed that PTEN gene might play a key role in the poor ability of axon regeneration in IB4~+ neurons.Therefore,we further investigate that whether inhibition of PTEN promotes axon regeneration in IB4~+ neurons or not.Methods:In vitro experiments,DRGs were cultured with two different PTEN gene inhibitors in it with or without sciatic nerve axotomy compared to the control group respectively.The length of axons in IB4~+ neurons were measured.In vivo experiments,PTENflox/flox mice were injected with AAV-Cre virus to knock out PTEN expression,then DRGs were harvested for culture,axon length of IB4~+ neurons were measured.Results:In vitro experiments,whether with or without sciatic nerve axotomy,the mean length of axons in IB4~+ neurons is much more longer in inhibit group than that in control group(p<0.05);In vivo experiments,the mean length of axons in IB4~+ neurons is longer in knockout group than that in control group(p<0.05).Conclusion:Inhibiting PTEN gene promotes axon regeneration in IB4~+ neurons.