O-080 Activated AKT/mTOR signalling in peripheral blood of women with premature ovarian insufficiency and its correlation with variable FMR1 expression profiles
Authors: Rehnitz J , Messmer B , Nguyen X P , Germeyer A , Hinderhofer K , Strowitzki T , Capp E 
Published: August 2021

Abstract

Study question
How predictive are gene expression levels of AKT/mTOR-signalling-pathway genes in peripheral blood of patients with premature ovary insufficiency (POI) and is there a link to FMR1-expression?

Summary answer
AKT1, TSC2, mTOR, S6K and FOXO3-expression-levels are significantly upregulated in POI-patients and demonstrate a positive correlation with FMR1-expression-level in case of mTOR-, S6K and FOXO3.

What is known already
The AKT/mTOR-signalling-pathway is involved in a range of cellular functions. In female germline it regulates early follicular-activation and follicular-pool-maintenance. Over the past few years AKT-activation has been experimentally applied to induce follicular maturation in POI-patients. Additionally, first evidence of a linked FMR1 – AKT/mTOR signaling in female germline have been reported.
FMR1 is a major control gene in folliculogenesis. Due to increased (CGG)-triplet-numbers (54 &lt; n &lt; 200) in its 5′-untranslated-region, named premutation, increased FMR1-expression-levels and reduced FMRP-production have been described, associated with POI in 20% of cases. A former study found premutation independent, large transcript-level-variances of FMR1 in leukocyte RNA-samples of POI-patients.

Study design, size, duration
74 POI patients and 56 fertile controls were prospectively enrolled in this study. Accordingly, expression levels of genes associated with the AKT/mTOR-signaling pathway and FMR1 were analyzed and correlated on the mRNA level of their leukocytes.

Participants/materials, setting, methods
All patients provided written informed consent. mRNA was extracted from EDTA blood after lysis; quantitative expression analyses of FMR1, AKT, mTOR, S6K, FOXO3, FOXO1 genes were performed with specific TaqMan-Assays. Statistical analyses was performed with SPSS; statistical significance was set to P &lt; 0.05.

Main results and the role of chance
Gene expression levels of AKT1, TSC2, mTOR, S6K, FOXO3 are significant higher in POI patients compared to controls (P &lt; 0.009 or less).
The rate of FMR1-expression is highly correlated with mTOR-, S6K and FOXO3-expression levels (P &lt; 0.001) in all patients, in addition. When grouped according to ovarian reserve this effect is more pronounced in POI than in control patients. Additionally, the correlation of FMR1 with FOXO3 remained significant only in the POI subgroup.
The upregulation of AKT/mTOR-signaling in POI may reflect a compensative mechanism in POI aiming the activation of the last remaining follicles.
The linkage of FMR1 with AKT/mTOR-signalling in peripheral blood comparable to prior results from germline, support its putative impact on the pathogenesis of POI and other folliculogenesis related disorders, such as poor ovarian response.

Limitations, reasons for caution
Results are based on limited patient numbers. More patients, stratified for age and other risks factors, are needed to further elucidate this mechanism.

Wider implications of the findings
This is the first evidence that FMR1 is linked to an AKT/mTOR activation in POI potentially involved in its pathogenesis. Such a marker in peripheral blood offers a perspective towards its usability as a predictive tool in the diagnostics and prognosis of POI, if results are consistent in further studies.

Trial registration number
not applicable