The phosphorylation and SUMOylation of spastin modulate AMPAR GluA2 subunits trafficking in hippocampal neurons

Point mutations in SPG4,the gene encoding spastin,are a frequent cause of hereditary spastic paraplegia(HSP).In some complex HSP cases,there is cognitive impairment.Dynamic trafficking of AMPA receptors into and out of synapses is a key determinant of synaptic plasticity and further implicates learning and memory.However,the exact molecular mechanisms underlying AMPARs trafficking still remains unclear.Here,we performed immunofluorescence staining,whole-cell patch clamp,GST pull-down,and CoIP assays.First,we found that the desumoylation mutant at 427-site of spastin lost its microtubule severing function.Second,our results revealed the maturation of dendritic spines and the increase of GluA2 membrane trafficking after overexpression de-SUMO spastin in cultured hippocampal neurons.Also,we found that the interaction between de SUMO spastin and the GluA2 subunits increased in vitro and in vivo,which were enhanced by the 210-site phosphorylation of spastin at the mean time.Similarly,the phosphorylation modifications enhanced the maturation of dendritic spines and the increasing membrane GluA2 caused by de SUMO spastin.Thus,we show the reciprocal regulation between the phosphorylation and sumoylation of spastin,and jointly modulate the AMPA receptor GluA2 subunits trafficking in cultured hippocampal neurons.

CRMP2 phosphorylation mediates dendritic spine plasticity and learning function in mice with subacute hepatic encephalopathy

Hepatic encephalopathy is defined as a spectrum of neuropsychiatric abnormalities in patients with liver dysfunction,after exclusion of brain disease.Despite extensive scientific research,the pathogenesis of hepatic encephalopathy is still unknown,and the most classic hypothesis is the theory of ammonia intoxication.Currently available evidence suggests that clinical hepatic encephalopathy cause impairments of astrocytic function resulting in neuronal dysfunction.In this study standardize an animal model of HE induced by thioacetamide(TAA)in C57BL/6 mice evaluating behavioral symptoms,and we performed immunofluorescence staining,whole cell patch clamp recording,Golgi staining.

Phosphorylation of spastin promotes the tafficking of AMPARs subunit GluA2 to mediate dendritic spine plasticity

Trafficking of AMPA receptors(AMPARs)to and.from synapses and their final localizations are critical for the expression of synaptic plasticity.Spastin is a member of the ATPases associated with diverse cellular activities(AAA)protein family,and contains a microtubule interacting and organelle transport(MIT)domain.However,less is known about the post-translational modification of spastin in the trafficking of AMPARs.Here we performed GST pull-down and Co-IP assays,immunofluorescence staining and whole cell patch clamp recording.In this study,we found that spastin interacts with AMPAR subunit GluA2 in vivo and in vitro and this binding is regulated by the phosphorylation of spastin.Second,phosphorylation of spastin promotes the maturation of dendritic spines by promoting the trafficking of GluA2 and increasing the amplitude and frequency of mEPSC.

CRMP2 promotesthe trafficking of phosphorylated AMPA receptor GluA2 subunit

CRMP2 is one of the well-studied members of the CRMPs family,which has been demonstrated not only play the roles in neurite extension,dendrites and dendritic spine development,but also in the AMPA receptor trafficking.However,the role of CRMP2 on the trafficking of AMPA receptor GluA2 subunit especially phosphorylated GluA2 is unknown.GST-Pull down and C-IP assays,immunofluorescence staining and whole cell patch clamp recording technique were performed in this study.The results showed that CRMP2 interacted with wild-type GluA2 and promoted the surface expression of wild-type GluA2.No matter GluA2 S880 was exogenously phosphorylated by phorbol myristate acetate(TPA)or endogenously phosphorylated by PKC5,CRMP2 can promote the surface expression of phosphorylated GluA2 and enhance its amplitude and frequency of mEPSCs,increasing the slope of the I-V curve.

Cardiac-Adaptive Conductive Hydrogel Patch Enabling Construction of Mechanical–Electrical Anisotropic Microenvironment for Heart Repair

The biomimetic construction of a microstructural–mechanical–electrical anisotropic microenvironment adaptive to the native cardiac tissue is essential to repair myocardial infarction(MI).Inspired by the 3D anisotropic characteristic of the natural fish swim bladder(FSB),a novel flexible,anisotropic,and conductive hydrogel was developed for tissue-specific adaptation to the anisotropic structural,conductive,and mechanical features of the native cardiac extracellular matrix.The results revealed that the originally stiff,homogeneous FSB film was tailored to a highly flexible anisotropic hydrogel,enabling its potential as a functional engineered cardiac patch(ECP).In vitro and in vivo experiments demonstrated the enhanced electrophysiological activity,maturation,elongation,and orientation of cardiomyocytes(CMs),and marked MI repair performance with reduced CM apoptosis and myocardial fibrosis,thereby promoting cell retention,myogenesis,and vascularization,as well as improving electrical integration.Our findings offer a potential strategy for functional ECP and provides a novel strategy to bionically simulate the complex cardiac repair environment.