Developmental Expression Of Drebrin And Icam-5 During Cerebral Spinogenesis And Synaptogenesis In FXS Mice

Objective:To observe the expression of Drebrin A,Drebrin E and Icam-5 mRNA in cerebral cortex during spinogenesis and synaptogenesis of the FMR-1 knock out mice and the control.Methods:This study assessed the level of target mRNA withβ-actin as internal control,measured by real-time PCR with reversed cDNA extracted from cerebral cortex at the developmental stage of spinogenesis and synaptogenesis in both the KO and control mice.Check points were set at day 7,14,21,and 28 after birth.Results:The level of Drebrin A mRNA increased till day 21 and followed a slight decline at day 28.In the KO group,a significantly lower expression was observed at day 14 compared to the control group(P<0.05);Drebrin E showed a dramatic drop after birth,fell to the lowest point at day 14,and descended mildly after that. Compared to the control,the KO group showed an apparently higher expression at day 14(P<0.01);The tendency of Icam-5 mRNA level assembled with Drebrin A, continuously ascended till day 21 and went down a bit at day 28,showing significantly higher expression at day 14 and 21 in KO group(p= 0.022,p=0.014).Conclusion:1. The delayed turnover of Drebrin A to Drebrin E and over expression of Icam-5 during critical stage of spinogenesis and synaptogenesis plays one of the key roles for the defective dendritic spines in Fragile X Syndrome(FXS).2.Dendritic external proteins, other than internal proteins,involved in the formation of aberrant morphology and function of dendrtic spines via signal transduction,enrich the precedent study into a more integral one.3.Likely underlying mechanism of Drebrin and Icam-5:A deficient and untimely expression of Drebrin A during spinogenesis and synaptogenesis results in dysfunctional dendritic protrusions,causing failure to contact axon terminals. For that reason the pruning of Icam-5 gets into trouble and consequentially maintains the dendritic filopodia and slows the maturation of dendritic protrusions.