P-606 Maintenance of telomere length through autophagy and androgen receptor inhibition in infertile individuals with differences of sex development (DSD)
Authors: Krivega M , Zimmer J , Slezko A , Frank-Herrmann P , Strowitzki T 
Published: July 2024

Abstract

Study question
What are the molecular mechanisms underlying genome instability concomitant with increased telomere length (TL) in individuals with DSD?

Summary answer
Low autophagy activity and androgen receptor signaling stabilize GAR1, a telomerase-specific protein, leading to an increase in TL in DSD cells.

What is known already
Increased genome instability is linked to infertility, and compromised telomere maintenance is associated with genome instability. Individuals with DSD, characterized by dysgenic gonads and a high risk of Germ Cell Tumor (GCT) development, exhibit concurrent genome instability, increased TL, and deregulated Androgen Receptor (AR) signaling. Telomeric DNA damage promotes autophagy, which induces cell death and prevents propagation of replication crisis and tumorigenesis. We previously demonstrated that inhibition of autophagy, a conservative process of protein degradation, led to TL increase in cell lines derived from individuals with DSD, but the underlying mechanisms remain unclear.

Study design, size, duration
112 individuals with DSD, including Swyer syndrome (46,XY females), Complete Androgen Insensitivity Syndrome (CAIS 46,XY females), Turner (45,X0 females), and Mixed Gonadal Dysgenesis (MGD 45,X0/46,XY females and males) were enrolled into study during routine praxis in our clinic. The samples were collected with written patients consent. A control group included fertile women and men, when appropriate, of comparable age. Samples underwent standard genetic and histological characterization. Lymphoblastoid cell lines were used for functional studies.

Participants/materials, setting, methods
Study groups comprised individuals with CAIS (n = 19); Swyer (n = 8); MGD (n = 12); Turner (n = 23) with mosaic (n = 12), with chr. X/Y deletions (n = 8), with X-isochr./idiocentric/marker chr. (n = 23) syndromes. Blood samples were collected for DNA, RNA and protein isolation from leukocytes. Additionally, individuals with DSD who underwent gonadectomy formed an additional group with histologically proven GCT (DSD-GCT, n = 7). Gonadal tissue was provided by the tissue bank. Samples were analyzed using quantitative real-time PCR (qRT-PCR), immunoblotting, and mass spectrometry.

Main results and the role of chance
Leukocytes from Swyer (p = 0,0069), Turner (p = 0,0064), and MGD without GCT (p = 0,05) groups exhibited a 1,5-folds increase in TL, diminished with GCT (p = 0,003). The RNA component of telomerase, TERC, was inhibited two times in Swyer (p = 0,0417). Proteomic analysis identified a telomerase protein GAR1 accumulation in Swyer, but downregulated in GCT group together with AR upregulation (p = 0,0379). Immunoblotting confirmed a two-fold increase of GAR1 in Swyer (p = 0,0022) and Turner (p = 0,0401), while GAR1 decreased in all DSD samples (p = 0,0455). GAR1 protein increased stability, not due to upregulated transcription, and promoted TL since we illustrated GAR1 accumulation within 72h of BafilomycinA1 treatment inhibiting autophagy. This treatment induced telomerase activity within 24h. Further autophagy inhibition caused accumulation of DNA damage in DSD cells, measured by γH2AX levels labeling double strand brakes (p = 0,0286). Dysgenic gonadal tissue analysis also showed a negative correlation between autophagy and TL-specific gene expression, with LC3 (p = 0,0341) and P62 (p = 0,0342) increased in all DSD samples, and proteins LC3 (p = 0,0298) and P62 (p = 0,0237) upregulated, and GAR1 (p = 0,0432) inhibited exclusively in Swyer group. Inhibition of AR increased TL (p = 0,0357) together with GAR1 (p = 0,0125) in DSD group at 19h, which was associated with a consecutive γH2AX upregulation (p = 0,0489) at 24h with Enzalutamide.

Limitations, reasons for caution
This study is based on a limited number of samples from the individuals with rare genetic syndromes, some observed only in 1 out of 10,000 clinical cases. Therefore, in vitro study models are recommended for further research.

Wider implications of the findings
The study reveals gene expression patterns and molecular regulatory mechanisms associated with DSD and GCT risk. The data suggest possibilities for prophylactic treatment of DSD individuals and new diagnostic approaches of GCT using peripheral blood. The study also emphasizes the importance of addressing genome integrity in infertility research.

Trial registration number
NA