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Updated: Jun 22, 2026
Oct4GiP Reporter Assay to Study Genes that Regulate Mouse Embryonic Stem Cell Maintenance and Self-renewal
Published on: May 30, 2012
PARP1 poly(ADP-ribosyl)ates Sox2 to control Sox2 protein levels and FGF4 expression during embryonic stem cell
Furong Gao1, Sung Won Kwon2, Yingming Zhao2
1Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institute of Biological Sciences, Chinese Academy of Sciences/Shanghai JiaoTong University School of Medicine, Shanghai 200025, China; Shanghai Stem Cell Institute, Shanghai JiaoTong University School of Medicine, Shanghai 200025, China; Graduate School of Chinese Academy of Sciences, Beijing 100000, China.
Abstract:
Transcription factors Oct4 and Sox2 are key players in maintaining the pluripotent state of embryonic stem cells (ESCs). Small changes in their levels disrupt normal expression of their target genes. However, it remains elusive how protein levels of Oct4 and Sox2 and expression of their target genes are precisely controlled in ESCs. Here we identify PARP1, a DNA-binding protein with an NAD+-dependent enzymatic activity, as a cofactor of Oct4 and Sox2 to regulate expression of their target gene FGF4. We demonstrate for the first time that PARP1 binds the FGF4 enhancer to positively regulate FGF4 expression. Our data show that PARP1 interacts with and poly(ADP-ribosyl)ates Sox2 directly, which may be a step required for dissociation and degradation of inhibitory Sox2 proteins from the FGF4 enhancer. When PARP1 activity is inhibited or absent, poly(ADP-ribosyl)ation of Sox2 decreases and association of Sox2 with FGF4 enhancers increases, accompanied by an elevated level of Sox2 proteins and reduced expression of FGF4. Significantly, specific knockdown of Sox2 expression by RNA interference can considerably abrogate the inhibitory effect of the poly(ADP-ribose) polymerase inhibitor on FGF4 expression. Interestingly, PARP1 deficiency does not affect undifferentiated ESCs but compromises cell survival and/or growth when ESCs are induced into differentiation. Addition of FGF4 can partially rescue the phenotypes caused by PARP1 deficiency during ESC differentiation. Taken together, this study uncovers new mechanisms through which Sox2 protein levels and FGF4 expression are dynamically regulated during ESC differentiation and adds a new member to the family of proteins regulating the properties of ESCs.
Insights
Poly(ADP-ribose) polymerase 1 (PARP1) regulates embryonic stem cell (ESC) differentiation by controlling Sox2 protein levels and FGF4 expression. PARP1
Area of Science:
- Stem Cell Biology
- Epigenetics
- Gene Regulation
Background:
- Oct4 and Sox2 are crucial transcription factors for maintaining embryonic stem cell (ESC) pluripotency.
- Precise control of Oct4 and Sox2 protein levels and their target gene expression is essential for ESC function.
- Mechanisms regulating these factors during ESC differentiation remain incompletely understood.
Purpose of the Study:
- To identify novel cofactors involved in regulating Oct4 and Sox2 activity in ESCs.
- To elucidate the role of PARP1 in controlling FGF4 expression and ESC differentiation.
- To understand the interplay between PARP1, Sox2, and FGF4 during ESC differentiation.
Main Methods:
- Chromatin immunoprecipitation (ChIP) to assess protein binding to the FGF4 enhancer.
- In vitro poly(ADP-ribosyl)ation assays to study PARP1-Sox2 interactions.
- RNA interference (RNAi) to knockdown Sox2 expression.
- PARP1 inhibition and deficiency studies in ESCs.
- Assessment of cell survival, growth, and FGF4 rescue experiments during differentiation.
Main Results:
- PARP1 acts as a cofactor for Oct4 and Sox2, directly binding the FGF4 enhancer to promote FGF4 expression.
- PARP1 poly(ADP-ribosyl)ates Sox2, facilitating its dissociation and degradation, thereby regulating Sox2 protein levels.
- PARP1 inhibition or deficiency leads to increased Sox2 association with the FGF4 enhancer, elevated Sox2 protein levels, and reduced FGF4 expression.
- PARP1 deficiency impairs ESC survival and growth during differentiation, which can be partially rescued by FGF4 addition.
- PARP1 deficiency does not affect undifferentiated ESCs but impacts differentiation.
Conclusions:
- PARP1 is a key regulator of Sox2 protein stability and FGF4 expression during ESC differentiation.
- PARP1-mediated regulation of Sox2 and FGF4 provides a novel mechanism for controlling ESC fate.
- This study identifies PARP1 as a new player in the complex network governing ESC properties and differentiation.
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