Insulin‐like growth factor 2 mRNA‐binding protein 2‐regulated alternative splicing of nuclear factor 1 C‐type causes excessive granulosa cell proliferation in polycystic ovary syndrome

Abstract

Objectives Polycystic ovary syndrome (PCOS) is a common reproductive endocrine disorder. Insulin‐like growth factor 2 mRNA‐binding protein 2 (IGF2BP2) serves as an HMGA2 target gene to promote the proliferation of granulosa cells (GCs). However, it is still unclear whether IGF2BP2 participates in the pathogenesis of PCOS as RNA binding protein (RBP). In this study, we aimed to elucidate IGF2BP2‐interacting transcripts, global transcriptome together with alternative splicing in GCs to eventually uncover potential mechanisms of PCOS pathogenesis. Materials and Methods The expression of IGF2BP2 in GCs from PCOS patients was detected using quantitative reverse transcription PCR (RT‐qPCR) and western blot. We captured IGF2BP2‐interacting transcripts, global transcriptome together with alternative splicing by RNA immunoprecipitation sequencing (RIP‐seq) and RNA sequencing (RNA‐seq). KGN cells transfected with IGF2BP2 overexpressing plasmids and nuclear factor 1 C‐type (NFIC) siRNAs, were applied to CCK‐8, EdU and TUNEL assays. Results IGF2BP2 was highly expressed in GCs from PCOS patients. As an RBP, it preferentially bound to the 3′and 5′UTRs of mRNAs with GGAC motif and a newly found GAAG motif. The overexpression of IGF2BP2 changed the transcriptome profile of KGN cells. IGF2BP2 functioned to regulate alternative splicing events and promote cell proliferation through inhibiting exon skipping events of NFIC. Conclusion In conclusion, we demonstrated that IGF2BP2 promotes GC proliferation via regulating alternative splicing of NFIC in PCOS. The findings help to better understand the roles of IGF2BP2 in the pathogenesis of PCOS.

IGF2BP2 and IGFBP3 Genotypes, Haplotypes, and Genetic Models Studies in Polycystic Ovary Syndrome

“…Thus, we hypothesized that insulin might also affect other members of the IGFBP family, such as IGF2BP2 and IGF2BP3, thereby influencing IGF levels. In PCOS patients, IGF2BP2 overexpression is associated with excessive proliferation of the GCs because it preferentially binds to mRNAs with AU‐rich elements (AREs) [13]. This is important because the induction of programmed cell death, called apoptosis, is responsible for the growth of GCs, therefore contributing to the etiology of PCOS [77].…”

“…Known as insulin-like growth factor II (IGF-II) mRNA-binding protein 2 (IGF2BP2), it binds to the crucial growth and insulin signaling molecule IGF-II. IGF2BP2 is encoded by the IGF2BP2 gene located on chromosome 3q27 [12,13]. PCOS is characterized by insulin resistance; therefore, SNPs linked to the insulin signaling pathways may contribute to the development of PCOS's clinical features [14].…”

“…Additionally, IGFBP3 is required for normal growth and development, like its counterparts IGF2BP2 and IGF mRNA-binding protein 3 (IMP-3). As a result of its attachment to the 5′UTR of the IGF-II leader 3 mRNA, they have a profound influence on post-transcriptional processes [12,13]. A relatively high expression of IGFBP3 is also found in the ovaries [18].…”

Zika virus remodels and hijacks IGF2BP2 ribonucleoprotein complex to promote viral replication organelle biogenesis

“…Most notably, ZIKV infection decreased IGF2BP2 interaction with 15 proteins of the mRNA splicing machinery. Interestingly, there is evidence that IGF2BP2 regulates mRNA splicing (38) in addition to its most characterized functions in mRNA stability and translation. Furthermore, several studies reported that ZIKV infection alters mRNA splicing (59)(60)(61).…”

Renal Endothelial Single-Cell Transcriptomics Reveals Spatiotemporal Regulation and Divergent Roles of Differential Gene Transcription and Alternative Splicing in Murine Diabetic Nephropathy

“…Figure S12). Some of these RBPs are known to regulate splicing, e.g., Rbm4b [44] at 6-week, Son [45] at 11/20-week, and Igf2bp2 [46] at 6/20-week.…”