Study Of The Proteins Interacted With MTSS1 From Neurons

Neurons are basic structural and functional units of nervous system.By polarization,migration and formation of synapses,neurons could establish mature circuits in brain.Purkinje neurons have the most complicated dendritic structure in central nervous system and maintain its plasticity after differentiation.They play important role in the motor memory.Tumor metastasis suppressor 1 protein(MTSS1),a kind of tumor metastasis-related actin binding protein,was reported to be involved in the polarization and migration of neuron in the development of central nervous system(CNS)recently.It has been reported that the temporal and spatial pattern of MTS S1 is regulated in the development of cerebellum.It maintained a high expression level after the maturation and mainly distributed in the cell body,axon and dendrite of Purkinje neuron.In this study,immunoprecipitation combined with mass spectrometry was used to screen MTS S1 interacting proteins.From the list of identified candidates,Homer3 and Collapsin response mediator protein 2(CRMP2)were selected for father study.Homer family,as one of the postsynaptic density protein family members,is an important linker between the synaptic contact cytoskeletal proteins and signaling proteins.Homer3 is a signal transduction regulatory protein and could interact various target proteins,including metabotropic glutamate receptor I,inositol triphosphate receptors and N-methyl-D-aspartate receptor Shank proteins.In Purkinje neuron,Homer3 is the major type of Homer protein family.It is widely distributed in dendrites,axons and cell body,but most notably in the accumulation of dendritic spines.In this study,the interaction of Homer3 with MTSS1 in cerebellum was verified by co-immunoprecipitation and pull down assay.The temporal pattern of Homer3 and MTSS1 in the postnatal development stages of rat cerebellum is similar.The distribution of MTSS1 in purkinje neuron is the same as that of the reported pattern of Homer3,indicating the connection between Homer3 and MTSS1 in the cerebellum.CRMP2 is one of the five subtypes of CRMP family in the developing nervous system.It plays an important role in the growth and polarization of axons.The interaction of CRMP2 with MTSS1 in brain is suggested by mass spectrum identification and pull down experiments.Further experimental results need to be done to verify the interaction.Except for immunoprecipitation,Blue native PAGE electrophoresis was used to exhibit the protein complex pattern of synaptosome from cerebellum and hippocampus.Our preliminary study suggested that the pattern of protein complex of the synaptosome from cerebellum is obvious different from that of hippocampus.In addition,the effect of MTSS1 on ?-actinin induced actin fiber was also investigated by transmission electron microscope and our result showed that MTSS1 could modify the morphology of the ?-actinin induced actin fiber.