FMRpolyG accumulates in FMR1 premutation granulosa cells

Area of Science:

• Reproductive Biology
• Neurogenetics
• Molecular Biology

Background:

• Fragile X premutation (55-200 CGG repeats) increases risk for FXPOI in females and FXTAS in males.
• CGG repeats trigger RAN translation of FMRpolyG, a protein found in FXTAS brain cells.
• FMRpolyG accumulation in ovarian cells of FXPOI patients suggests a potential role in folliculogenesis.

Purpose of the Study:

• To investigate FMRpolyG accumulation in mural granulosa cells of FMR1 premutation carriers.
• To evaluate COV434 cells transfected with premutation repeats as a model for FXPOI pathogenesis.

Main Methods:

• Immunohistochemistry was used to detect FMRpolyG and ubiquitin in granulosa cells from carriers and controls.
• COV434 cells were transfected with plasmids expressing CGG repeats to enable FMRpolyG expression.

Main Results:

• FMRpolyG aggregates were detected in mural granulosa cells of FMR1 premutation carriers, but not in controls.
• FMRpolyG and ubiquitin co-localization varied among carriers.
• Transfected COV434 cells showed FMRpolyG aggregates, mirroring findings in carrier granulosa cells.

Conclusions:

• FMRpolyG accumulates in mural granulosa cells of FMR1 premutation carriers, consistent with FXTAS findings.
• Premutation-transfected COV434 cells may serve as a model for studying RAN translation in FXPOI.
• FMRpolyG accumulation in ovarian cells suggests a shared protein-mediated toxic mechanism in FXPOI and FXTAS.