FMR1
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| Location (UCSC) | Chr X: 147.91 – 147.95 Mb | Chr X: 67.72 – 67.76 Mb | |||||||
| PubMed search | [3] | [4] | |||||||
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FMR1 (Fragile X Messenger Ribonucleoprotein 1) is a
Function
Synaptic plasticity
FMRP has a diverse array of functions throughout different areas of the neuron; however these functions have not been fully characterized. FMRP has been suggested to play roles in nucleocytoplasmic shuttling of
Group 1 metabotropic glutamate receptor (mGluR) signaling has been implicated in playing an important role in FMRP-dependent synaptic plasticity. Post-synaptic mGluR stimulation results in the up-regulation of protein synthesis through a second messenger system.[11] A role for mGluR in synaptic plasticity is further evidenced by the observation of dendritic spine elongation following mGluR stimulation.[12] Furthermore, mGluR activation results in the synthesis of FMRP near synapses. The produced FMRP associates with polyribosomal complexes after mGluR stimulation, proposing the involvement of Fragile X Messenger Ribonucleoprotein in the process of translation. This further advocates a role for FMRP in synaptic protein synthesis and the growth of synaptic connections.[13] The loss of FMRP results in an abnormal dendritic spine phenotype. Specifically, deletion of the FMR1 gene in a sample of mice resulted in an increase in spine synapse number.[14]
Role in translation
The proposed mechanism of FMRP's effect upon synaptic plasticity are through its role as a negative regulator of translation. FMRP is an RNA-binding protein which associates with
FMRP has been shown to inhibit translation of mRNA. Mutation of the FMRP protein resulted in the inability to repress translation as opposed to the wild-type counterpart which was able to do so.[17] As previously mentioned, mGluR stimulation is associated with increased FMRP protein levels. In addition, mGluR stimulation results in increased levels of FMRP target mRNAs. A study found basal levels of proteins encoded by these target mRNAs to be significantly elevated and improperly regulated in FMRP deficient mice.[18]
FMRP translation repression acts by inhibiting the initiation of translation. FMRP directly binds
FMRP translational control has been shown to be regulated by mGluR signaling. mGluR stimulation may result in the transportation of mRNA complexes to synapses for local protein synthesis. FMRP granules have been shown to localize with
Gene expression
The FMR1 gene is located on the
FMRP is a chromatin-binding protein that functions in the DNA damage response.[26][27] FMRP occupies sites on meiotic chromosomes and regulates the dynamics of the DNA damage response machinery during spermatogenesis.[26]
The FMR1 gene can be found on the long (q) arm of the X chromosome at position 27.3, from base pair 146,699,054 to base pair 146,738,156
Related conditions
Fragile X syndrome
Almost all cases of fragile X syndrome are caused by expansion of the CGG trinucleotide repeat in the FMR1 gene. In these cases, CGG is abnormally repeated from 200 to more than 1,000 times. As a result, this part of the FMR1 gene is methylated, which silences the gene (it is turned off and does not make any protein). Without adequate FMR1, severe learning disabilities or intellectual disabilities can develop, along with physical abnormalities seen in fragile X syndrome.
Fewer than 1% of all cases of fragile X syndrome are caused by mutations that delete part or all of the FMR1 gene, or change a base pair, leading to a change in one of the amino acids in the gene. These mutations disrupt the 3-dimensional shape of FMRP or prevent the protein from being synthesized, leading to the signs and symptoms of fragile X syndrome.
A CGG sequence in the FMR1 gene that is repeated between 55 and 200 times is described as a premutation. Although most individuals with the premutation are intellectually normal, some of these individuals have mild versions of the physical features seen in fragile X syndrome (such as prominent ears) and may experience mental health problems such as anxiety or depression.
Fragile X-associated tremor/ataxia syndrome
Premutations are associated with an increased risk of
Premature ovarian aging
The FMR1 gene plays a very important role in ovarian function, independent from cognitive/neurological effects. Minor expansions of CGG repeats that do not cause
Polycystic ovarian syndrome
A very specific sub-genotype of FMR1 has been found to be associated with
Interactions
FMR1 has been shown to
References
- ^ a b c GRCh38: Ensembl release 89: ENSG00000102081 – Ensembl, May 2017
- ^ a b c GRCm38: Ensembl release 89: ENSMUSG00000000838 – Ensembl, May 2017
- ^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
- ^ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
- S2CID 21463845.
- S2CID 4331494.
- ^ "Fragile X Messenger Ribonucleoprotein 1" The Human Gene Compendium
- S2CID 16002209.
- ^ PMID 16098134.
- PMID 12032354.
- PMID 8102206.
- PMID 11818568.
- ^ PMID 9144248.
- S2CID 18257268.
- PMID 9624140.
- S2CID 35339859.
- PMID 11157796.
- ^ S2CID 13915959.
- ^ S2CID 14123165.
- PMID 17507556.
- S2CID 14892764.
- S2CID 24629325.
- American College of Medical Genetics. 2000-10-02. Retrieved 2013-03-29.
- PMID 23064752.
- PMID 25608779.
- ^ PMID 24813610.
- S2CID 44159474.
- S2CID 26409068.
- PMID 19712568.
- PMID 18973899.
- ^ PMID 11438699.
- ^ PMID 12837692.
- ^ PMID 8668200.
- ^ PMID 7489725.
- PMID 10567518.
- PMID 10556305.
Further reading
- Bassell GJ, Warren ST (October 2008). "Fragile X syndrome: loss of local mRNA regulation alters synaptic development and function". Neuron. 60 (2): 201–14. PMID 18957214.
- Hagerman PJ, Hagerman RJ (May 2004). "The fragile-X premutation: a maturing perspective". American Journal of Human Genetics. 74 (5): 805–16. PMID 15052536.
- Hagerman RJ, Leavitt BR, Farzin F, Jacquemont S, Greco CM, Brunberg JA, Tassone F, Hessl D, Harris SW, Zhang L, Jardini T, Gane LW, Ferranti J, Ruiz L, Leehey MA, Grigsby J, Hagerman PJ (May 2004). "Fragile-X-associated tremor/ataxia syndrome (FXTAS) in females with the FMR1 premutation". American Journal of Human Genetics. 74 (5): 1051–6. PMID 15065016.
- Jacquemont S, Hagerman RJ, Leehey MA, Hall DA, Levine RA, Brunberg JA, Zhang L, Jardini T, Gane LW, Harris SW, Herman K, Grigsby J, Greco CM, Berry-Kravis E, Tassone F, Hagerman PJ (January 2004). "Penetrance of the fragile X-associated tremor/ataxia syndrome in a premutation carrier population". JAMA. 291 (4): 460–9. PMID 14747503.
- Jin P, Alisch RS, Warren ST (November 2004). "RNA and microRNAs in fragile X mental retardation". Nature Cell Biology. 6 (11): 1048–53. S2CID 7315938.
- Jin P, Warren ST (March 2003). "New insights into fragile X syndrome: from molecules to neurobehaviors". Trends in Biochemical Sciences. 28 (3): 152–8. PMID 12633995.
- O'Donnell WT, Warren ST (2002). "A decade of molecular studies of fragile X syndrome". Annual Review of Neuroscience. 25: 315–38. PMID 12052912.
- Oostra BA, Chiurazzi P (December 2001). "The fragile X gene and its function". Clinical Genetics. 60 (6): 399–408. S2CID 40128119.
- Oostra BA, Willemsen R (October 2003). "A fragile balance: FMR1 expression levels". Human Molecular Genetics. 12 Spec No 2 (90002): R249–57. PMID 12952862.
- Nicola NA, Metcalf D (October 1991). "Subunit promiscuity among hemopoietic growth factor receptors". Cell. 67 (1): 1–4. S2CID 12696714.
- Sielska D, Milewski M, Bal J (2003). "[Molecular pathogenesis of fragile X syndrome]". Medycyna Wieku Rozwojowego. 6 (4): 295–308. PMID 12810982.
- Bagni C, Greenough WT (May 2005). "From mRNP trafficking to spine dysmorphogenesis: the roots of fragile X syndrome". Nature Reviews. Neuroscience. 6 (5): 376–87. S2CID 17374547.
- Huber KM (April 2006). "The fragile X-cerebellum connection". Trends in Neurosciences. 29 (4): 183–5. S2CID 8674692.
- Loesch DZ, Bui QM, Dissanayake C, Clifford S, Gould E, Bulhak-Paterson D, Tassone F, Taylor AK, Hessl D, Hagerman R, Huggins RM (2007). "Molecular and cognitive predictors of the continuum of autistic behaviours in fragile X". Neuroscience and Biobehavioral Reviews. 31 (3): 315–26. PMID 17097142.
External links
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