Fragile X mental retardation protein (FMRP), a causative gene (FMR1) product of Fragile X syndrome (FXS), is an RNA-binding protein to regulate local protein synthesis in dendrites for postsynaptic functions.
Whether fragile X mental retardation protein (FMRP) target mRNAs and neuronal activity contributing to elevated basal neuronal protein synthesis in fragile X syndrome (FXS) is unclear.
Lack or mutations of FMRP lead to Fragile X Syndrome (FXS), the most common form of inherited intellectual disability and a leading monogenic cause of autism spectrum disorder (ASD).
Fragile X syndrome (FXS) is the most common cause of inherited intellectual disabilities and autism spectrum disorders, and it is an X-linked disorder in which there is a deficiency of the fragile X mental retardation 1 protein.
<b>Background</b>: Fragile X Syndrome (FXS), the most common cause of inherited intellectual disability (ID), is caused by a CGG repeat expansion (full mutation (FM), >200 CGG) at the Fragile X Mental Retardation 1 (FMR1) gene.
Using metabolomics, in vivo metabolic phenotyping of the Fmr1-KO FXS mouse model and in vitro approaches, we show that the absence of FMRP induced a metabolic shift towards enhanced glucose tolerance and insulin sensitivity, reduced adiposity, and increased β-adrenergic-driven lipolysis and lipid utilization.
Loss of regulated Cav2.3 expression could underlie the neuronal hyperactivity and aberrant calcium spiking in FMRP KO mice and contribute to FXS, potentially serving as a novel target for future therapeutic strategies.<b>SIGNIFICANCE STATEMENT</b> Patients with fragile X syndrome (FXS) exhibit signs of neuronal and circuit hyperexcitability, including anxiety and hyperactive behavior, attention deficit disorder, and seizures.
Twenty children and adolescents (aged 6-17 years) with a diagnosis of FXS (confirmed through molecular documentation of FMR1 full mutation) were enrolled in an open-label, multi-site, trial of ZYN002.
The functional absence of FMRP causes the fragile X syndrome (FXS), the most common form of inherited intellectual disability and the most common monogenic cause of autism.
Numerous preclinical studies have supported the theory that enhanced activation of mGluR5 signaling, due to the absence or reduction of the FMR1 protein, contributes to cognitive and behavioral deficits in patients with fragile X syndrome (FXS).
Synaptic plasticity, protein synthesis, and cellular growth pathways have been studied extensively in hippocampal slices from a mouse model of FXS (Fmr1 KO).
Here, we also explore the possibility that recently reported missense mutations in the FMR1 gene disrupt the PTM homoeostasis of FMRP, thus participating in the aetiology of FXS.
Our results from animals of both sexes suggest that the modulation of the Kv3.1 channel may have potential for the treatment of sensory hypersensitivity in patients with FXS.<b>SIGNIFICANCE STATEMENT</b> mRNA encoding the Kv3.1 potassium channel was one of the first described targets of the fragile X mental retardation protein (FMRP).
FMR1 CGG trinucleotide repeat expansions are associated with Fragile X syndrome (full mutations) and primary ovarian insufficiency (premutation range); the effect of FMR1 on the success of fertility treatment is unclear.
In this review, we highlight these advances and discuss how these new findings could contribute to our understanding of FMRP in brain development and function, the neural pathology of fragile X syndrome, and perhaps impact of future therapeutic considerations.
In aggregate, our study provides a novel approach to understand the molecular basis of FXS by linking the dysregulated synaptic expression of NLGNs with FMRP.
We found that the previously published Fmr1 knockout rat model of FXS expresses an Fmr1 transcript with an in-frame deletion of exon 8, which encodes for the K-homology (KH) RNA-binding domain, KH1.