Project description:Fragile-X Syndrome (FXS) is a multi-organ disease leading to mental retardation, macro-orchidism in males, and premature ovarian insufficiency in female carriers. FXS is also a prominent monogenic disease associated with autism spectrum disorders (ASD). FXS is typically caused by the loss of FRAGILE X-MENTAL RETARDATION 1 (FMR1) expression, which encodes for the RNA-binding protein (RBP), FMR1 (or FMRP). We report the discovery of the RNA recognition elements (RREs), binding sites, and mRNA targets for wild-type and I304N mutant FMRP isoforms as well as its paralogs, FXR1 and FXR2. RRE frequency, ratio, and distribution determine target mRNA association with FMRP. Among highly-enriched targets, we identified many genes involved in ASD and demonstrate that FMRP can affect their protein levels in cell culture, mice, and human brain. Unexpectedly, we discovered that these targets are also dysregulated in Fmr1-/- mouse ovaries, showing signs of premature follicular overdevelopment. These results indicate that FMRP targets shared signaling pathways across different cellular contexts. As it is become increasingly appreciated that signaling pathways are important to FXS and ASD, our results here provide an invaluable molecular guide towards the pursuit of novel therapeutic targets for these devastating neurological disorders. The mRNA profile of RNA recovered from FLAG-antibody immunoprecipitated FMRP was compared to the mRNA profile of the starting lysate material.
Project description:Fragile-X Syndrome (FXS) is a multi-organ disease leading to mental retardation, macro-orchidism in males, and premature ovarian insufficiency in female carriers. FXS is also a prominent monogenic disease associated with autism spectrum disorders (ASD). FXS is typically caused by the loss of FRAGILE X-MENTAL RETARDATION 1 (FMR1) expression, which encodes for the RNA-binding protein (RBP), FMR1 (or FMRP). We report the discovery of the RNA recognition elements (RREs), binding sites, and mRNA targets for wild-type and I304N mutant FMRP isoforms as well as its paralogs, FXR1 and FXR2. RRE frequency, ratio, and distribution determine target mRNA association with FMRP. Among highly-enriched targets, we identified many genes involved in ASD and demonstrate that FMRP can affect their protein levels in cell culture, mice, and human brain. Unexpectedly, we discovered that these targets are also dysregulated in Fmr1-/- mouse ovaries, showing signs of premature follicular overdevelopment. These results indicate that FMRP targets shared signaling pathways across different cellular contexts. As it is become increasingly appreciated that signaling pathways are important to FXS and ASD, our results here provide an invaluable molecular guide towards the pursuit of novel therapeutic targets for these devastating neurological disorders. PAR-CLIP profiling for wild-type and I304N mutant FMRP isoforms as well as paralogs, FXR1 and FXR2.
Project description:Fragile-X Syndrome (FXS) is a multi-organ disease leading to mental retardation, macro-orchidism in males, and premature ovarian insufficiency in female carriers. FXS is also a prominent monogenic disease associated with autism spectrum disorders (ASD). FXS is typically caused by the loss of FRAGILE X-MENTAL RETARDATION 1 (FMR1) expression, which encodes for the RNA-binding protein (RBP), FMR1 (or FMRP). We report the discovery of the RNA recognition elements (RREs), binding sites, and mRNA targets for wild-type and I304N mutant FMRP isoforms as well as its paralogs, FXR1 and FXR2. RRE frequency, ratio, and distribution determine target mRNA association with FMRP. Among highly-enriched targets, we identified many genes involved in ASD and demonstrate that FMRP can affect their protein levels in cell culture, mice, and human brain. Unexpectedly, we discovered that these targets are also dysregulated in Fmr1-/- mouse ovaries, showing signs of premature follicular overdevelopment. These results indicate that FMRP targets shared signaling pathways across different cellular contexts. As it is become increasingly appreciated that signaling pathways are important to FXS and ASD, our results here provide an invaluable molecular guide towards the pursuit of novel therapeutic targets for these devastating neurological disorders.
Project description:Fragile-X Syndrome (FXS) is a multi-organ disease leading to mental retardation, macro-orchidism in males, and premature ovarian insufficiency in female carriers. FXS is also a prominent monogenic disease associated with autism spectrum disorders (ASD). FXS is typically caused by the loss of FRAGILE X-MENTAL RETARDATION 1 (FMR1) expression, which encodes for the RNA-binding protein (RBP), FMR1 (or FMRP). We report the discovery of the RNA recognition elements (RREs), binding sites, and mRNA targets for wild-type and I304N mutant FMRP isoforms as well as its paralogs, FXR1 and FXR2. RRE frequency, ratio, and distribution determine target mRNA association with FMRP. Among highly-enriched targets, we identified many genes involved in ASD and demonstrate that FMRP can affect their protein levels in cell culture, mice, and human brain. Unexpectedly, we discovered that these targets are also dysregulated in Fmr1-/- mouse ovaries, showing signs of premature follicular overdevelopment. These results indicate that FMRP targets shared signaling pathways across different cellular contexts. As it is become increasingly appreciated that signaling pathways are important to FXS and ASD, our results here provide an invaluable molecular guide towards the pursuit of novel therapeutic targets for these devastating neurological disorders.
Project description:The Fragile X Mental Retardation Protein, FMRP, is thought to regulate the translation of a specific set of neuronal mRNAs on polyribosomes. Therefore, we prepared polyribosomes on sucrose gradients and purified mRNA specifically from these fractions, as well as the total mRNA levels, to determine whether a set of mRNAs might be changed in its % association with polyribosomes in the absence of FMRP in the KO mouse model. No significant differences were found, other than the Fmr1 transcript itself, in total mRNA levels or % polyribosome association that withstood multiple test correction, in P7 Fmr1 KO mouse cerebral cortex compared with WT littermates.. We prepared polyribosomes on sucrose gradients from 6 littermate pairs of Fmr1 KO and WT littermates (FVB background, P7 males, cerebral cortex) and purified RNA from both polyribosomal fractions and input to the gradient, reflecting total mRNA levels for comparison.
Project description:N6-methyladenosine (m6A) modification of mRNA is emerging as a vital mechanism regulating RNA function. Here, we show that fragile X mental retardation protein (FMRP), an RNA-binding protein, reads m6A to regulate nuclear export of methylated mRNA targets during neural stem cell differentiation. In Fmr1 KO mice neural progenitors show delayed cell cycle exit and differentiation, resulting in their progressive accumulation in the ventricular and subventricular zones. RNA-seq of neural precursor cells (NPCs) from Fmr1 KO mice and m6A-seq uncovered nuclear retention of m6A-modified FMRP target mRNAs involved in regulating neural differentiation, including components of Notch and Hedgehog signaling pathways. Analysis of NPCs from Mettl14 cKO mice, which are devoid of m6A, revealed that methylation of RNAs promotes their nuclear export through CRM1. Altogether, our findings suggest that FMRP reads and facilitates nuclear export of m6A-modified mRNAs to regulate neural stem cell differentiation, contributing to Fragile X syndrome.
Project description:Maternal RNA degradation is critical for embryogenesis and is tightly controlled by maternal RNA-binding proteins. Fragile X mental-retardation protein (FMR1) binds target mRNAs to form ribonucleoprotein (RNP) complexes/granules that control various biological processes, including early embryogenesis. However, how FMR1 recognizes target mRNAs and how FMR1-RNP granule assembly/disassembly regulates FMR1-associated mRNAs remain elusive. Here we show that Drosophila FMR1 preferentially binds mRNAs containing m6A-marked “AGACU” motif with high affinity to contributes to maternal RNA degradation. The high-affinity binding largely depends on a hydrophobic network within FMR1 KH2 domain. Importantly, this binding greatly induces FMR1 granule condensation to efficiently recruit unmodified mRNAs. The degradation of maternal mRNAs then causes granule de-condensation, allowing normal embryogenesis. Our findings reveal that sequence-specific mRNAs instruct FMR1-RNP granules to undergo a dynamic phase-switch, thus contributes to maternal mRNA decay. This mechanism may represent a general principle that regulated RNP-granules control RNA processing and normal development.
Project description:The Fragile X Mental Retardation Protein, FMRP, is thought to regulate the translation of a specific set of neuronal mRNAs on polyribosomes. Therefore, we prepared polyribosomes on sucrose gradients and purified mRNA specifically from these fractions, as well as the total mRNA levels, to determine whether a set of mRNAs might be changed in its % association with polyribosomes in the absence of FMRP in the KO mouse model. No significant differences were found, other than the Fmr1 transcript itself, in total mRNA levels or % polyribosome association that withstood multiple test correction, in P7 Fmr1 KO mouse cerebral cortex compared with WT littermates..