Restoring FMRP Phenotypes Frpm Temporal Regional and Splice- Isoforms Varations

点击翻译按钮获取中文摘要

PROJECT IV: WILLIAM GREENOUGH RESTORING FMRP: PHENOTYPES FROM TEMPORAL, REGIONAL, AND SPLICE-ISOFORM VARIATIONS Fragile X syndrome (FXS) is the most frequent cause of inherited mental retardation. Certain treatments appear to restore/rescue particular WT phenotypic characteristics in the fmM-knockout mouse model. Gene reintroduction or replacement is becoming a serious future alternative, with research well under way. However, the FXS phenotype is heterogeneous. An array of features of the nervous system appear to be affected. While pharmacological treatments that affect a single neurotransmitter system may ameliorate some symptons (e.g. MPEP reduction of audiogenic seizure susceptibility in the Fmr1 KO mouse), the growing evidence of multiple isoforms of the Fragile X protein, the role of the Fragile X gene in the course of brain development, and a strategy for viral-vector delivery of the gene. The proposed work begins (Aim 1) by addressing the presumably varied roles of the different isoforms of the FMRP in terms of their relationship to phenotype by assessing a range of phenotypes in mice able to produce only single isoforms. The outcomes of these studies will inform our first attempts at viral-driven expression of exogenous FMRP (Aim 3), using those isoforms that were particularly effective in Aim 1. Finally, Aim2 investigates the stability and permanence of symptoms in the presence of restoration of the complete gene at selected stages in development. Our methods will include investigations of the neuroanatomical phenotypes of spine shape, spine density and dendritic field conformation, not just as static images but at the morphology changes over time with respect to afferent activity, using, in addition to conventional approaches, intrinsically-YFP-labeled neurons and multiple two-photon microscopic views over time of the developing spine and dendritic network. In addition, we will employ a biomarker, ERK phosphoylation, as a criterion for normallyfunctioning cellular signaling cascades, to characterize tissues with transient or permanent restoration of full or partial arrays of FMRP molecules.