Manganese Superoxide Dismutase Gene Expression Is Induced by Nanog and Oct4, Essential Pluripotent Stem Cells’ Transcription Factors

Abstract

Pluripotent stem cells possess complex systems that protect them from oxidative stress and ensure genomic stability, vital for their role in development. Even though it has been reported that antioxidant activity diminishes along stem cell differentiation, little is known about the transcriptional regulation of the involved genes. The reported modulation of some of these genes led us to hypothesize that some of them could be regulated by the transcription factors critical for self-renewal and pluripotency in embryonic stem cells (ESCs) and in induced pluripotent stem cells (iPSCs). In this work, we studied the expression profile of multiple genes involved in antioxidant defense systems in both ESCs and iPSCs. We found that Manganese superoxide dismutase gene (Mn-Sod/Sod2) was repressed during diverse differentiation protocols showing an expression pattern similar to Nanog gene. Moreover, Sod2 promoter activity was induced by Oct4 and Nanog when we performed a transactivation assay using two different reporter constructions. Finally, we studied Sod2 gene regulation by modulating the expression of Oct4 and Nanog in ESCs by shRNAs and found that downregulation of any of them reduced Sod2 expression. Our results indicate that pluripotency transcription factors positively modulate Sod2 gene transcription.

Insights into the Dichotomous Regulation of SOD2 in Cancer

“…In stem cells, transcription of the SOD2 gene has been shown to be Nanog and Oct4-dependent based on promoter activity assays and RNAi-mediated knockdown of the two pluripotency transcription factors [ 125 ]. Potential Nanog, Oct4, and Sox2 binding sites are located at the 5′ upstream of the SOD2 gene transcription start site, suggesting that these transcription factors may regulate SOD2 in a stem cell-like state [ 125 ].…”

“…In stem cells, transcription of the SOD2 gene has been shown to be Nanog and Oct4-dependent based on promoter activity assays and RNAi-mediated knockdown of the two pluripotency transcription factors [ 125 ]. Potential Nanog, Oct4, and Sox2 binding sites are located at the 5′ upstream of the SOD2 gene transcription start site, suggesting that these transcription factors may regulate SOD2 in a stem cell-like state [ 125 ]. Inhibiting mechanistic Target Of Rapamycin (mTOR) by rapamycin has also been demonstrated to increase SOD2 expression in self-renewing keratinocytes and confers radioprotective effects to these cells [ 126 ], as previously described for hematopoietic progenitor cells [ 127 ].…”

The pluripotency transcription factor Nanog represses glutathione reductase gene expression in mouse embryonic stem cells

“…Based on the growing evidence that antioxidant defense system is modulated when pluripotent stem cells are induced to differentiate, and that glutathione reductase is an important enzyme involved in the cellular response to oxidative stress, we decided to study Gsr gene modulation. In a previous work, we have in silico analyzed the upstream region of the coding sequence of diverse genes involved in antioxidant system, including Gsr and found the presence of multiple predicted binding sites for the transcription factors Oct4 and Nanog in a 5 kbp region upstream the transcription start site of this gene [16]. In this work, we first studied Gsr gene modulation in undifferentiated ESCs and along differentiation.…”

“…Based on the reported modulation of this system and its importance in securing genomic stability and cellular functions, we hypothesized that some of the antioxidant genes are regulated by the transcription factors fundamental for pluripotency, such as Oct4, Sox2 and Nanog. We have previously found that both sod1 and sod2 genes, that encode for superoxide dismutases, are induced by the pluripotency transcription factors, which are essential for ESCs’ self-renewal and pluripotency [16, 17].…”

Mitochondrial Superoxide Dismutase Specifies Early Neural Commitment by Modulating Mitochondrial Dynamics

“…Previous studies from our laboratory and others had elucidated the role of SOD2 in maintaining stem cell pluripotency ( Sheshadri et al., 2015 ; Solari et al., 2015 ). Following this observation, we expected that its inhibition would enhance tri-lineage differentiation of mESCs.…”