SRSF7 downregulation induces cellular senescence through generation of MDM2 variants
Jiwon Hong1,2,3, Seongki Min1,2,3, Gyesoon Yoon1,2,3
1Department of Biochemistry and Molecular Biology, Ajou University School of Medicine, Suwon 16499, Korea.
Abstract:
Alternative splicing (AS) enables a pre-mRNA to generate different functional protein variants. The change in AS has been reported as an emerging contributor to cellular senescence and aging. However, it remains to be elucidated which senescent AS variants are generated in and regulate senescence. Here, we observed commonly down-regulated SRSF7 in senescent cells, using publicly available RNA-seq datasets of several in vitro senescence models. We further confirmed SRSF7 deregulation from our previous microarray datasets of time-series replicative senescence (RS) and oxidative stress-induced senescence (OSIS) of human diploid fibroblast (HDF). We validated the time-course changes of SRSF mRNA and protein levels, developing both RS and OSIS. SRSF knockdown in HDF was enough to induce senescence, accompanied by p53 protein stabilization and MDM2 variants formation. Interestingly, expression of MDM2 variants showed similar patterns of p53 expression in both RS and OSIS. Next, we identified MDM2-C as a key functional AS variant generated specifically by SRSF7 depletion. Finally, we validated that MDM2-C overexpression induced senescence of HDF. These results indicate that SRSF7 down-regulation plays a key role in p53-mediated senescence by regulating AS of MDM2, a key negative regulator of p53, implying its critical involvement in the entry into cell senescence.
Insights
Down-regulation of SRSF7 triggers cellular senescence by altering alternative splicing of MDM2. This leads to p53 stabilization and the formation of senescent-inducing MDM2 variants, highlighting SRSF7
Area of Science:
- Molecular Biology
- Cellular Senescence
- RNA Splicing
Background:
- Alternative splicing (AS) generates diverse protein variants from a single pre-mRNA.
- Altered AS is increasingly recognized as a factor in cellular senescence and aging.
- The specific AS variants involved in senescence regulation remain largely unknown.
Purpose of the Study:
- To identify senescent AS variants and elucidate their regulatory roles.
- To investigate the function of SRSF7 in cellular senescence.
- To determine the link between SRSF7, MDM2 splicing, and p53-mediated senescence.
Main Methods:
- Analysis of RNA-seq and microarray datasets from in vitro senescence models.
- SRSF7 knockdown experiments in human diploid fibroblasts (HDFs).
- Validation of mRNA and protein levels, p53 stabilization, and MDM2 variant formation.
- Identification and functional validation of the MDM2-C AS variant.
Main Results:
- SRSF7 was commonly down-regulated in senescent cells.
- SRSF7 knockdown induced senescence, p53 stabilization, and MDM2 variant formation in HDFs.
- MDM2-C was identified as a key functional AS variant specifically generated by SRSF7 depletion.
- Overexpression of MDM2-C induced senescence in HDFs.
Conclusions:
- SRSF7 down-regulation is a critical event in p53-mediated senescence.
- SRSF7 regulates the alternative splicing of MDM2, a key negative regulator of p53.
- The identified MDM2-C variant plays a significant role in the induction of cellular senescence.
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