Multiple variants of intellectual disability, e.g., the Fragile X Syndrome are associated with alterations in dendritic spine morphology, thereby pointing to dysregulated actin dynamics during development and processes of synaptic plasticity. Surprisingly, although the necessity of spine actin remodeling was demonstrated repeatedly, the importance and precise role of actin regulators is often undervalued. Here, we provide evidence that structural and functional plasticity are severely impaired after NMDAR-dependent LTP in the hippocampus of Fmr1 KO mice. We can link these defects to an aberrant activity-dependent regulation of Cofilin 1 (cof1) as activity-dependent modulations of local cof1 mRNA availability, local cof1 translation as well as total cof1 expression are impaired in the absence of FMRP. Finally, we can rescue activity-dependent structural plasticity in KO neurons by mimicking the regulation of cof1 observed in WT cells, thereby illustrating the potential of actin modulators to provide novel treatment strategies for the Fragile X Syndrome.

中文翻译：

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FMRP通过结合Cofilin1 mRNA和调节定位和本地翻译来调节活动依赖的脊柱可塑性。

智力残疾的多种变体，例如脆性X综合征与树突棘形态的改变有关，从而指出突触可塑性发展和过程中肌动蛋白动力学失调。令人惊讶的是，尽管反复证明了脊柱肌动蛋白重塑的必要性，但肌动蛋白调节剂的重要性和确切作用常常被低估了。在这里，我们提供的证据表明Fmr1 KO小鼠海马中NMDAR依赖性LTP后，结构和功能可塑性受到严重损害。我们可以将这些缺陷与Cofilin 1（cof1）的异常依赖于活动的调节联系起来，因为在缺乏FMRP的情况下，对局部cof1 mRNA可用性，局部cof1翻译以及总cof1表达的依赖活动的调节受到损害。最后，