TGF-β1 regulates the lncRNA transcriptome of ovarian granulosa cells in a transcription activity-dependent manner

Transforming growth factor β1 (TGF-β1), an essential cytokine belongs to TGF-β superfamily, is crucial for female fertility. Increasing evidence show that long noncoding RNAs (lncRNAs) influence the state of granulosa cells (GCs). This study aimed to detect the effects of TGF-β1 on the lncRNA transcriptome, and investigate whether lncRNAs mediate the functions of TGF-β1 in GCs.

RNA-seq and bioinformatics analyses were performed to identify and characterize the differentially expressed lncRNAs (DElncRNAs). The regulatory mechanism of TGF-β1 to lncRNA transcriptome was analyzed by chromatin immunoprecipitation. The effects of lncRNAs on the antiapoptotic and proproliferative functions of TGF-β1 were examined by morphological analysis, fluorescence-activated cell sorting, Cell Counting Kit-8, and Western blot.

A total of 72 DElncRNAs highly sensitive to TGF-β1 were identified with the criteria of |log₂ (fold chage)| ≥ 3 and false discovery rate < 0.05. Functional assessment showed that DElncRNAs were enriched in TGF-β, nuclear factor kappa B, p53, and Hippo pathways which are crucial for the normal state and function of GCs. Importantly, SMAD4 is essential for the regulation of TGF-β1 to lncRNA transcriptome. In vitro studies confirmed that TGF-β1 induced TEX14-IT1 transcription in a SMAD4-dependent manner, and TEX14-IT1 mediated the antiapoptotic and proproliferative effects of TGF-β1 in GCs.

Our findings demonstrate that TGF-β1 alters lncRNA transcriptome in a SMAD4-dependent manner, and highlight that lncRNAs mediate the functions of TGF-β1 in GCs, which contribute to a better understanding of the epigenetic regulation of female fertility.