The Mechanism Of SUMOylated Spastin To Regulate The Maturity Of Dendritic Spine In Hippocampal Neurons

Objective and significance Changes in synaptic plasticity after spinal cord injury(dendritic spine density or maturity)are critical for the repair of spinal cord injury.Dendritic spines are the structural basis of postsynaptic,and their morphology is closely related to synaptic plasticity.Current research reports on Spastin mainly include axonal transport,axon branching and lateral branch formation.SUMO modification plays an important role in the nervous system and synapse formation,and our group has verified that Spastin can be SUMOylated previously.But whether Spastin and different states of SUMOmodified Spastin were able to regulate synaptic plasticity is still needed elucidated.The objective of this study is to demonstrate how SUMOylation affects Spastin on the regulation of dendrite growth and synaptic plasticity.Exploring the regulation mechanism of SUMOylated Spastin in dendritic development will not only help us understand the regulation mechanism of neuronal development,but also the essential processes of neurological diseases and nerve injury,thus providing a new theoretical support for the treatment of neurodevelopmental disorders and nerve injury diseases.Materials and Methods We firstly used immunocytochemical staining to determine whether Spastin and SUMO1 were co-localized in dendrites and dendritic spines.Then,Spastin and its SUMOylated or de SUMOylated Spastin plasmids were constructed and overexpressed in hippocampal neurons cultured in vitro.Subsequently,the SUMO-modification of the role of Spastin in dendritic elongation,branch formation and dendritic spine development were observed.The expression of Glu A1 on the surface of neuronal cell membrane was observed.Finally,by tracking the distribution of endosomal proteins and Glu A1,we explored how Spastin and its SUMOylated or de SUMOylated Spastin affect the Glu A1 trafficking.Results 1.Spastin and SUMO1 proteins co-localize in dendrites and dendritic spines.2.Overexpression of Spastin can promote the elongation and branch formation of neuronal dendrites,while overexpression of the SUMOylation mutant SpastinK427 R does not promote dendritic elongation and branch formation.3.Overexpression of Spastin,SUMOylated or de SUMOylated Spastin has no significant effect on the density of dendritic spines.But overexpression of Spastin increases the proportion of thin-like dendritic spines,and dendritic spines tend to be immature.De SUMOylated Spastin mutant Spastin-K427 R increase the mushroom-like dendritic spines,and the dendritic spines tend to mature.4.Overexpression of Spastin and co-transfection of Spastin and SUMO1 can promote the internalization of Glu A1.De SUMOylated Spastin mutant Spastin-K427 R increased the expression of dendritic Glu A1 membrane in hippocampal neurons.The introduction of SENP1 significantly reduced the extent of Glu A1 internalization induced by Spastin.5.Overexpression of Spastin increased the colocalization of LAMP1 and Glu A1,but there was no significant increase in the colocalization of early endocytosis and midstage swallows and Glu A1.Furthermore,the SUMOylation mutant Spastin-K427 R can reduce the colocalization of LAMP1 and Glu A1.Conclusions 1.SUMOylated n Spastin can promote the elongation and branch of dendrites in hippocampal neurons,making dendritic spines tend to be slender,and the expression of Glu A1 membrane is decreased.After de SUMOylation,Spastin does not promote dendritic elongation and branch formation,dendritic spines tend to mature,and Glu A1 membrane expression is increased.2.SUMOylated Spastin-mediated internalization of Glu A1 is transported by late endocytic LAMP1.The reduction of Glu A1 transported by this pathway after Spastin was de SUMOylated.