LncRNA-THBS4 affects granulosa cell proliferation and apoptosis in diminished ovarian reserve by regulating PI3K/AKT/mTOR signaling pathway.

Backgrounds: Recent studies have found Several lncRNAs were proved differential expression in diminished ovarian reserve (DOR) patients, however, the mechanism of DOR caused by lncRNAs is still largely unclear.

Methods: High throughput sequencing was performed in ovarian GCs extracted from women with normal ovarian function and women with DOR. Bioinformation analysis was used to analyze the sequencing data and identify the differential expression of lncRNAs. Quantitative RT-PCR (qRT-PCR) was used to verify the sequencing results. Situ fluorescence hybridization (FISH) followed by confocal microscopy and qRT-PCR were used to explore the location and expression of LncRNA-THBS4 in GCs. The significantly enriched signaling pathways of LncRNA-THBS4 were identified by KEGG. The study used RNA interference technology to decipher LncRNA-THBS4 function by silencing LncRNA-THBS4 in GCs. Western blot and qRT-PCR were used to explore the mRNA and protein expressions of key factors of PI3Ks pathway. The pro-apoptotic protein and anti-apoptotic protein were detected by western blot. The proliferation and apoptosis of GCs were detected by MTT assay and Flow cytometry.

Results: 197 lncRNAs with significant differences in expression levels were detected between control and DOR group by high throughput sequencing. The study found the expression of LncRNA-THBS4 in GCs was positively correlated with Anti-Mullerian hormone (AMH) (p = 0.0020, r = 0.4742)、antral follicle count (AFC) (p = 0.0007, r = 0.5130)、good embryo rate (p = 0.0006, r = 0.5210), negatively correlated with basal FSH level (p = 0.0007, r = －0.5152). LncRNA-THBS4 was mainly localized in the cytoplasm of GCs. LncRNA-THBS4 silencing could inhibit the PI3Ks pathway; decrease the levels of anti-apoptotic protein, inhibit the proliferation of GCs; increase the levels of apoptosis protein, enhance the apoptosis of GCs.

Conclusions: The expression level of lncRNA-THBS4 is correlated with ovarian function indicators and pregnancy outcomes in women. LncRNA-THBS4 may participate in the pathogenesis of DOR by affecting the proliferation and apoptosis of GCs via regulating PI3K/AKT/mTOR signaling pathway.