Axonal localization of the Fragile X family of RNA binding proteins is conserved across mammals

2018 ◽  
Author(s):  
Katherine A. Shepard ◽  
Lulu I T. Korsak ◽  
Michael R. Akins

AbstractSpatial segregation of proteins to neuronal axons arises in part from local translation of select mRNAs that are first transported into axons in ribonucleoprotein particles (RNPs), complexes containing mRNAs and RNA binding proteins. Understanding the importance of local translation for a particular circuit requires not only identifying axonal RNPs and their mRNA cargoes, but also whether these RNPs are broadly conserved or restricted to only a few species. Fragile X granules (FXGs) are axonal RNPs containing the Fragile X related family of RNA binding proteins along with ribosomes and specific mRNAs. FXGs were previously identified in mouse, rat, and human brains in a conserved subset of neuronal circuits but with species-dependent developmental profiles. Here we asked whether FXGs are a broadly conserved feature of the mammalian brain and sought to better understand the species-dependent developmental expression pattern. We found FXGs in a conserved subset of neurons and circuits in the brains of every examined species that together include mammalian taxa separated by up to 160 million years of divergent evolution. A developmental analysis of rodents revealed that FXG expression in frontal cortex and olfactory bulb followed consistent patterns in all species examined. In contrast, FXGs in hippocampal mossy fibers showed an increase in abundance across development for most species except for guinea pigs and members of the Mus genus, animals that navigate particularly small home ranges in the wild. The widespread conservation of FXGs suggests that axonal translation is an ancient, conserved mechanism for regulating the proteome of mammalian axons.

Author(s):  
Kent E. Duncan

Both RNA-binding proteins (RBPs) and translation are increasingly implicated in several neurodegenerative diseases, but their specific roles in promoting disease are not yet fully defined. This chapter critically evaluates the evidence that altered translation of specific mRNAs mediated by RNA-binding proteins plays an important role in driving specific neurodegenerative diseases. First, diseases are discussed where a causal role for RNA-binding proteins in disease appears solid, but whether this involves altered translation is less clear. The main foci here are TAR DNA-binding protein (TDP-43) and fused in sarcoma (FUS) in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Subsequently, diseases are presented where altered translation is believed to contribute, but involvement of RNA-binding proteins is less clear. These include Huntington’s and other repeat expansion disorders such as fragile X tremor/ataxia syndrome (FXTAS), where repeat-induced non-AUG-initiated (RAN) translation is a focus. The potential contribution of both canonical and non-canonical RBPs to altered translation in Parkinson’s disease is discussed. The chapter closes by proposing key research frontiers for the field to explore and outlining methodological advances that could help to address them.


Biomolecules ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 167 ◽  
Author(s):  
Ohashi ◽  
Shiina

Spatiotemporal translational regulation plays a key role in determining cell fate and function. Specifically, in neurons, local translation in dendrites is essential for synaptic plasticity and long-term memory formation. To achieve local translation, RNA-binding proteins in RNA granules regulate target mRNA stability, localization, and translation. To date, mRNAs localized to dendrites have been identified by comprehensive analyses. In addition, mRNAs associated with and regulated by RNA-binding proteins have been identified using various methods in many studies. However, the results obtained from these numerous studies have not been compiled together. In this review, we have catalogued mRNAs that are localized to dendrites and are associated with and regulated by the RNA-binding proteins fragile X mental retardation protein (FMRP), RNA granule protein 105 (RNG105, also known as Caprin1), Ras-GAP SH3 domain binding protein (G3BP), cytoplasmic polyadenylation element binding protein 1 (CPEB1), and staufen double-stranded RNA binding proteins 1 and 2 (Stau1 and Stau2) in RNA granules. This review provides comprehensive information on dendritic mRNAs, the neuronal functions of mRNA-encoded proteins, the association of dendritic mRNAs with RNA-binding proteins in RNA granules, and the effects of RNA-binding proteins on mRNA regulation. These findings provide insights into the mechanistic basis of protein-synthesis-dependent synaptic plasticity and memory formation and contribute to future efforts to understand the physiological implications of local regulation of dendritic mRNAs in neurons.


2019 ◽  
Vol 528 (3) ◽  
pp. 502-519 ◽  
Author(s):  
Katherine A. Shepard ◽  
Lulu I T. Korsak ◽  
Danielle DeBartolo ◽  
Michael R. Akins

2016 ◽  
Vol 94 (6) ◽  
pp. 597-608 ◽  
Author(s):  
M. McCoy ◽  
D. Poliquin-Duchesneau ◽  
F. Corbin

Asymmetrically differentiating cells are formed with the aid of RNA-binding proteins (RBPs), which can bind, stabilize, regulate, and transport target mRNAs. The loss of RBPs in neurons may lead to severe neurodevelopmental diseases such as the Fragile X Syndrome with the absence of the Fragile X Mental Retardation Protein (FMRP). Because the latter is ubiquitous and shares many similarities with other RBPs involved in the development of peripheral cells, we suggest that FMRP would have a role in the differentiation of all tissues where it is expressed. A MEG-01 differentiation model was, therefore, established to study the global developmental functions of FMRP. PMA induction of MEG-01 cells causes important morphological changes driven by cytoskeletal dynamics. Cytoskeleton change and colocalization analyses were performed by confocal microscopy and sucrose gradient fractionation. Total cellular protein content and de novo synthesis were also analyzed. Microtubular transport mediates the displacement of FMRP and other RBP-containing mRNP complexes towards regions of the cell in development. De novo protein synthesis decreases significantly upon differentiation and total protein content composition is altered. Because those results are comparable with those obtained in neurons, the absence of FMRP would have significant consequences in cells everywhere in the body. The latter should be further investigated to give a better understanding of the systemic implications of imbalances of FMRP and other functionally similar RBPs.


eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Raeann Goering ◽  
Laura I Hudish ◽  
Bryan B Guzman ◽  
Nisha Raj ◽  
Gary J Bassell ◽  
...  

The sorting of RNA molecules to subcellular locations facilitates the activity of spatially restricted processes. We have analyzed subcellular transcriptomes of FMRP-null mouse neuronal cells to identify transcripts that depend on FMRP for efficient transport to neurites. We found that these transcripts contain an enrichment of G-quadruplex sequences in their 3′ UTRs, suggesting that FMRP recognizes them to promote RNA localization. We observed similar results in neurons derived from Fragile X Syndrome patients. We identified the RGG domain of FMRP as important for binding G-quadruplexes and the transport of G-quadruplex-containing transcripts. Finally, we found that the translation and localization targets of FMRP were distinct and that an FMRP mutant that is unable to bind ribosomes still promoted localization of G-quadruplex-containing messages. This suggests that these two regulatory modes of FMRP may be functionally separated. These results provide a framework for the elucidation of similar mechanisms governed by other RNA-binding proteins.


2014 ◽  
Vol 90 (5) ◽  
Author(s):  
Jessie M. Sutherland ◽  
Barbara A. Fraser ◽  
Alexander P. Sobinoff ◽  
Victoria J. Pye ◽  
Tara-Lynne Davidson ◽  
...  

Reproduction ◽  
2005 ◽  
Vol 130 (2) ◽  
pp. 203-212 ◽  
Author(s):  
Niels A Hammer ◽  
Thomas v O Hansen ◽  
Anne Grete Byskov ◽  
Eva Rajpert-De Meyts ◽  
Marie Louise Grøndahl ◽  
...  

Insulin-like growth factor-II mRNA-binding proteins 1, 2 and 3 (IMP1, IMP2 and IMP3) belong to a family of RNA-binding proteins implicated in mRNA localization, turnover and translational control. We examined their expression pattern during development of murine and human testis and ovaries. In the mouse, IMPs were expressed in male and female gonadal cells at embryonic day 12.5 (E12.5). From E16.5, IMP1 and IMP3 became restricted to the developing germ cells, whereas IMP2 expression persisted in the interstitial cells. In mature mouse and human ovaries, IMP1, IMP2 and IMP3 were detected in resting and growing oocytes and in the granulosa cells. In testis, IMP1 and IMP3 were found mainly in the spermatogonia, whereas IMP2 was expressed in the immature Leydig cells. Moreover, all three IMPs were detected in human semen. The developmental expression pattern of IMP1 and IMP3 in the human testis prompted us to examine their possible involvement in testicular neoplasia. IMPs were detected primarily in germ-cell neoplasms, including preinvasive testicular carcinoma in situ, classical and spermatocytic seminoma, and nonseminomas, with particularly high expression in undifferentiated embryonal carcinoma. The relative expression of IMP1, IMP2 and IMP3 varied among tumor types and only IMP1 was detected in all carcinoma in situ cells. Thus IMPs, and in particular IMP1, may be useful auxiliary markers of testicular neoplasia.


Neuron ◽  
2007 ◽  
Vol 55 (4) ◽  
pp. 565-571 ◽  
Author(s):  
Oyinkan A. Sofola ◽  
Peng Jin ◽  
Yunlong Qin ◽  
Ranhui Duan ◽  
Huijie Liu ◽  
...  

Author(s):  
Claudia Bagni ◽  
Eric Klann

Chapter 8 discusses how Fragile X syndrome (FXS) is caused by the absence of the RNA-binding protein fragile X mental retardation protein (FMRP). FMRP is highly expressed in the brain and gonads, the two organs mainly affected in patients with the syndrome. Functionally, FMRP belongs to the family of RNA-binding proteins, shuttling from the nucleus to the cytoplasm, and, as shown for other RNA-binding proteins, forms large messenger ribonucleoparticles.


Sign in / Sign up

Export Citation Format

Share Document