GSE196454
Early Postnatal Alterations in Follicular Stress Response and Survival in a Mouse Model of Classic Galactosemia
Primary ovarian insufficiency (POI) is characterized by accelerated loss of primordial follicles, which results in ovarian failure and concomitant menopause before age 40.  1-3% of females in the general population are diagnosed with POI and 80% of females with the inherited disease Classic Galactosemia (CG) will develop POI. CG is caused by mutations in the GALT gene encoding the enzyme galactose-1-phosphate uridylyltransferase.  While dietary restriction of galactose is lifesaving in the neonatal period, the development of severe complications including POI is not mitigated.  Additionally, the pattern of follicle loss have not been completely characterized.  The chronic accumulation of aberrant metabolites such as galactose-1 phosphate and galactitol are the suspected culprits in the development of the sequelae, yet the mechanisms remain elusive.   Our group uses a GalT gene-trapped mouse model to study the pathophysiology of CG.  Recently, we showed that alterations in the Integrated Stress Response pathway occur in the ovaries of these mice, likely contributing to the POI phenotype.  Using immunofluorescent staining in whole-ovary histology at progressive ages, we saw evidence of altered Integrated Stress Response activity in granulosa cells and primordial oocytes leading to accelerated primordial follicle growth, aberrant DNA damage repair, and increased cellular stress/death.  RNA-sequencing of whole ovary revealed significant alterations in cholesterol/lipid metabolism and transcriptional regulation.   Overall, our findings indicate abnormal stress response results in accelerated primordial follicle activation or “burnout,” which may explain the POI phenotype of fewer primordial follicles at later ages. Overall design: We extracted RNA from 3 wildtype and 3 mutant mouse ovaries at P49; Both genotypes were treated with a diet containing 2.5% galactose for 4 weeks after weaning.