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Presence of inclusions positive for polyglycine containing protein, FMRpolyG, indicates that repeat-associated non-AUG translation plays a role in fragile X-associated primary ovarian insufficiency
- Source :
- Human reproduction (Oxford, England), vol 31, iss 1, Human Reproduction, 31(1), 158-168. Oxford University Press
- Publication Year :
- 2015
- Publisher :
- Oxford University Press (OUP), 2015.
-
Abstract
- STUDY QUESTION Does repeat-associated non-AUG (RAN) translation play a role in fragile X-associated primary ovarian insufficiency (FXPOI), leading to the presence of polyglycine containing protein (FMRpolyG)-positive inclusions in ovarian tissue? SUMMARY ANSWER Ovaries of a woman with FXPOI and of an Fmr1 premutation (PM) mouse model (exCGG-KI) contain intranuclear inclusions that stain positive for both FMRpolyG and ubiquitin. WHAT IS KNOWN ALREADY Women who carry the FMR1 PM are at 20-fold increased risk to develop primary ovarian insufficiency (FXPOI). A toxic RNA gain-of-function has been suggested as the underlying mechanism since the PM results in increased levels of mRNA containing an expanded repeat, but reduced protein levels of fragile X mental retardation protein (FMRP). Recently, RAN translation has been shown to occur from FMR1 mRNA that contains PM repeat expansions, leading to FMRpolyG inclusions in brain and non-CNS tissues of fragile X-associated tremor/ataxia syndrome (FXTAS) patients. STUDY DESIGN, SIZE, DURATION Ovaries of a woman with FXPOI and women without PM (controls), and ovaries from wild-type and exCGG-KI mice were analyzed by immunohistochemistry for the presence of inclusions that stained for ubiquitin and FMRpolyG . The ovaries from wild-type and exCGG-KI mice were further characterized for the number of follicles, Fmr1 mRNA levels and FMRP protein expression. The presence of inclusions was also analyzed in pituitaries of a man with FXTAS and the exCGG-KI mice. PARTICIPANTS/MATERIALS, SETTING, METHODS Human ovaries from a woman with FXPOI and two control subjects and pituitaries from a man with FXTAS and a control subjects were fixed in 4% formalin. Ovaries and pituitaries of wild-type and exCGG mice were fixed in Bouin's fluid or 4% paraformaldehyde. Immunohistochemistry was performed on the human and mouse samples using FMRpolyG, ubiquitin and Fmrp antibodies. Fmr1 mRNA and protein expression were determined in mouse ovaries by quantitative RT-PCR and Western blot analysis. Follicle numbers in mouse ovaries were determined in serial sections by microscopy. MAIN RESULTS AND THE ROLE OF CHANCE FMRpolyG-positive inclusions were present in ovarian stromal cells of a woman with FXPOI but not in the ovaries of control subjects. The FMRpolyG-positive inclusions colocalized with ubiquitin-positive inclusions. Similar inclusions were also observed in the pituitary of a man with FXTAS but not in control subjects. Similarly, ovaries of 40-week-old exCGG-KI mice, but not wild-type mice, contained numerous inclusions in the stromal cells that stained for both FMRpolyG- and ubiquitin, while the ovaries of 20-week-old exCGG-KI contained fewer inclusions. At 40 weeks ovarian Fmr1 mRNA expression was increased by 5-fold in exCGG-KI mice compared with wild-type mice, while Fmrp expression was reduced by 2-fold. With respect to ovarian function in exCGG-KI mice: (i) although the number of healthy growing follicles did not differ between wild-type and exCGG-KI mice, the number of atretic large antral follicles was increased by nearly 9-fold in 40-week old exCGG-KI mice (P < 0.001); (ii) at 40 weeks of age only 50% of exCGG-KI mice had recent ovulations compared with 89% in wild-type mice (P = 0.07) and (iii) those exCGG-KI mice with recent ovulations tended to have a reduced number of fresh corpora lutea (4.8 ± 1.74 versus 8.50 ± 0.98, exCGG-KI versus wild-type mice, respectively, P = 0.07). LIMITATIONS, REASONS FOR CAUTION Although FMRpolyG-positive inclusions were detected in ovaries of both a woman with FXPOI and a mouse model of the FMR1 PM, we only analyzed one ovary from a FXPOI subject. Caution is needed to extrapolate these results to all women with the FMR1 PM. Furthermore, the functional consequence of FMRpolyG-positive inclusions in the ovaries for reproduction remains to be determined. WIDER IMPLICATIONS OF THE FINDINGS Our results suggest that a dysfunctional hypothalamic-pituitary-gonadal-axis may contribute to FXPOI in FMR1 PM carriers. STUDY FUNDING/COMPETING INTERESTS This study was supported by grants from NFXF, ZonMW, the Netherlands Brain Foundation and NIH. The authors have no conflict of interest to declare.
- Subjects :
- Male
0301 basic medicine
inclusions
Intranuclear Inclusion Bodies
ovarian failure
Hypothalamic–pituitary–gonadal axis
Primary Ovarian Insufficiency
Inbred C57BL
Medical and Health Sciences
Mice
Fragile X Mental Retardation Protein
Tremor
2.1 Biological and endogenous factors
Aetiology
FXPOI
media_common
Rehabilitation
Obstetrics and Gynecology
Middle Aged
HPG-axis
medicine.anatomical_structure
Studies in Human Society
FMRpolyG
Immunohistochemistry
Female
trinucleotide repeat expansion
Adult
medicine.medical_specialty
Intellectual and Developmental Disabilities (IDD)
media_common.quotation_subject
Ovary
Biology
03 medical and health sciences
Follicle
Rare Diseases
RAN translation
Internal medicine
Genetics
medicine
Animals
Humans
Ovarian follicle
Obstetrics & Reproductive Medicine
Ovulation
Aged
Animal
Neurosciences
CGG-repeat
Original Articles
Antral follicle
FMR1
Brain Disorders
Mice, Inbred C57BL
Disease Models, Animal
030104 developmental biology
Endocrinology
Reproductive Medicine
Fragile X Syndrome
Disease Models
Mutation
Ataxia
FXTAS
Trinucleotide Repeat Expansion
Peptides
FMR1 premutation
Subjects
Details
- ISSN :
- 14602350 and 02681161
- Volume :
- 31
- Database :
- OpenAIRE
- Journal :
- Human Reproduction
- Accession number :
- edsair.doi.dedup.....1b1a07b1c912550de6e3285da2d51674