FMRP - G-quadruplex mRNA - miR-125a interactions: Implications for miR-125a mediated translation regulation of PSD-95 mRNA.

Fragile X syndrome, the most common inherited form of intellectual disability, is caused by the CGG trinucleotide expansion in the 5'-untranslated region of the Fmr1 gene on the X chromosome, which silences the expression of the fragile X mental retardation protein (FMRP). FMRP has been shown to bind to a G-rich region within the PSD-95 mRNA, which encodes for the postsynaptic density protein 95, and together with microRNA-125a to mediate the reversible inhibition of the PSD-95 mRNA translation in neurons. The miR-125a binding site within the PSD-95 mRNA 3'-untranslated region (UTR) is embedded in a G-rich region bound by FMRP, which we have previously demonstrated folds into two parallel G-quadruplex structures.

hnRNP-Q1 represses nascent axon growth in cortical neurons by inhibiting Gap-43 mRNA translation.

Posttranscriptional regulation of gene expression by mRNA-binding proteins is critical for neuronal development and function. hnRNP-Q1 is an mRNA-binding protein that regulates mRNA processing events, including translational repression. hnRNP-Q1 is highly expressed in brain tissue, suggesting a function in regulating genes critical for neuronal development.

Fragile X mental retardation protein interactions with a G quadruplex structure in the 3'-untranslated region of NR2B mRNA.

Fragile X syndrome, the most common cause of inherited intellectual disability, is caused by a trinucleotide CGG expansion in the 5'-untranslated region of the FMR1 gene, which leads to the loss of expression of the fragile X mental retardation protein (FMRP). FMRP, an RNA-binding protein that regulates the translation of specific mRNAs, has been shown to bind a subset of its mRNA targets by recognizing G quadruplex structures. It has been suggested that FMRP controls the local protein synthesis of several protein components of the post synaptic density (PSD) in response to specific cellular needs.

G quadruplex RNA structures in PSD-95 mRNA: potential regulators of miR-125a seed binding site accessibility.

Fragile X syndrome (FXS) is the most common inherited form of intellectual disability caused by the CGG trinucleotide expansion in the 3'-untranslated region of the FMR1 gene on the X chromosome, that silences the expression of the Fragile X mental retardation protein (FMRP). FMRP has been shown to bind to a G-rich region within the PSD-95 mRNA which encodes for the postsynaptic density protein 95 (PSD-95), and together with the microRNA miR-125a, to play an important role in the reversible inhibition of the PSD-95 mRNA translation in neurons. The loss of FMRP in Fmr1 KO mice disables this translation control in the production of the PSD-95 protein.

Hepatitis C virus RNA: molecular switches mediated by long-range RNA-RNA interactions?

Multiple conserved structural cis-acting regulatory elements have been recognized both in the coding and untranslated regions (UTRs) of the hepatitis C virus (HCV) genome. For example, the cis-element 5BSL3.2 in the HCV-coding region has been predicted to use both its apical and internal loops to interact with the X RNA in the 3'-UTR, with the IIId domain in the 5'-UTR and with the Alt sequence in the coding region.