Developmental expression of the fragile X-related 1 proteins in mouse testis: association with microtubule elements
M E Huot1, R Mazroui, P Leclerc
1Unité de Recherche en Génétique Humaine et Moléculaire, Hôpital St. François d'Assise du CHUQ, 10, rue de l'Espinay, Québec G1L 3L5, Canada.
Abstract:
Fragile X mental retardation 1 protein (FMRP) is the archetype of a class of cytoplasmic mRNA-binding proteins that includes the fragile X-related 1 and 2 proteins (FXR1P and FXR2P). Whereas absence of FMRP is the cause of fragile X syndrome, it is not known if FXR1P and FXR2P are associated with any pathology. It is also still elusive whether these homologous proteins can partially compensate for the absence of FMRP in the case of the fragile X syndrome. FXR1 is widely expressed in mammals and its expression pattern is complex since several mRNA variants and protein isoforms are detected. In mouse, we observed that the highest level of FXR1 is found in the adult testis. This tissue is an exception, since all known FXR1P isoforms, some of which have been considered as tissue specific, are detected in it. In young animals, changes in mRNA-spliced variants and their corresponding protein isoforms occur during spermatogenesis. Using biochemical, immunohistochemical and electron microscopic techniques, we show that FXR1P is associated with microtubule elements. Since the cytoskeletal framework is implicated in cellular plasticity as well as in mRNA transport, we propose new possibilities for the function(s) of the FXR proteins.
Insights
Fragile X mental retardation 1 protein (FMRP) and its homologs FXR1P and FXR2P are key in cellular function. FXR1P associates with microtubules, suggesting roles in mRNA transport and cellular plasticity.
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- Fragile X mental retardation 1 protein (FMRP) absence causes fragile X syndrome.
- The roles and pathologies associated with homologous proteins FXR1P and FXR2P remain unclear.
- It is unknown if FXR1P and FXR2P can compensate for FMRP deficiency in fragile X syndrome.
Purpose of the Study:
- Investigate the expression pattern and cellular localization of FXR1 protein (FXR1P).
- Explore the potential functions of FXR1P, particularly in relation to cytoskeletal elements.
- Examine the complexity of FXR1 expression, including mRNA variants and protein isoforms.
Main Methods:
- Biochemical analysis
- Immunohistochemistry
- Electron microscopy
- Analysis of mRNA variants and protein isoforms during spermatogenesis in mice.
Main Results:
- FXR1 exhibits a complex expression pattern with multiple mRNA variants and protein isoforms.
- The adult mouse testis displays the highest level of FXR1 expression, containing all known FXR1P isoforms.
- Changes in FXR1 mRNA and protein isoforms occur during spermatogenesis in young mice.
- FXR1P was found to be associated with microtubule elements within the cell.
Conclusions:
- FXR1P's association with microtubules suggests a role in cytoskeletal functions.
- The findings propose novel possibilities for FXR protein functions, potentially involving mRNA transport and cellular plasticity.
- Further research is warranted to elucidate the specific roles of FXR1P and FXR2P in cellular processes and their potential involvement in fragile X syndrome.
More Related Videos
11:10Dissecting Cell-Autonomous Function of Fragile X Mental Retardation Protein in an Auditory Circuit by In Ovo Electroporation
Published on: July 6, 2022
10:59Generation and Characterization of Human Induced Pluripotent Stem Cell-derived Astrocytes Lacking Fragile X Messenger Ribonucleoprotein
Published on: June 6, 2025
Related Concept Videos
01:43Sex-linked Disorders
02:19The Y Chromosome Determines Maleness
Evolution
Around 300 million years ago, the two sex chromosomes diverged from two identical autosomal chromosomes. Over time, the Y chromosome has lost most of its genes, shrinking in size. Today,...