Binding of 14-3-3 reader proteins to phosphorylated DNMT1 facilitates aberrant DNA methylation and gene expression

Abstract

Mammalian DNA (cytosine-5) methyltransferase 1 (DNMT1) is essential for maintenance methylation. Phosphorylation of Ser143 (pSer143) stabilizes DNMT1 during DNA replication. Here, we show 14-3-3 is a reader protein of DNMT1pSer143. In mammalian cells 14-3-3 colocalizes and binds DNMT1pSer143 post-DNA replication. The level of DNMT1pSer143 increased with overexpression of 14-3-3 and decreased by its depletion. Binding of 14-3-3 proteins with DNMT1pSer143 resulted in inhibition of DNA methylation activity in vitro. In addition, overexpression of 14-3-3 in NIH3T3 cells led to decrease in DNMT1 specific activity resulting in hypomethylation of the genome that was rescued by transfection of DNMT1. Genes representing cell migration, mobility, proliferation and focal adhesion pathway were hypomethylated and overexpressed. Furthermore, overexpression of 14-3-3 also resulted in enhanced cell invasion. Analysis of TCGA breast cancer patient data showed significant correlation for DNA hypomethylation and reduced patient survival with increased 14-3-3 expressions. Therefore, we suggest that 14-3-3 is a crucial reader of DNMT1pSer143 that regulates DNA methylation and altered gene expression that contributes to cell invasion.

Gene expression analysis of heat-shock proteins and redox regulators reveals combinatorial prognostic markers in carcinomas of the gastrointestinal tract

“…We observed a strong negative correlation between DNAJA4 gene methylation and expression in stomach adenocarcinoma, which suggested that methylation of DNAJA4 may suppress gene expression. This is consistent with reports that DNAJA4 expression is strongly influenced by its methylation status [58]. Our data also revealed that patients with low DNAJA4 expression had poorer survival outcomes.…”

Allosteric control of mammalian DNA methyltransferases – a new regulatory paradigm

“…The S143 of DNMT1 is phosphorylated by AKT1, which leads to the stabilization of the methyltransferase ( 99 ). Recently, a specific 14-3-3 family reader protein for this modification was identified ( 100 ). It binds to the phosphorylated DNMT1, leading to the inhibition of DNMT1 activity in vitro and in cells, and subsequent aberrant DNA hypomethylation ( 100 ).…”

“…Recently, a specific 14-3-3 family reader protein for this modification was identified ( 100 ). It binds to the phosphorylated DNMT1, leading to the inhibition of DNMT1 activity in vitro and in cells, and subsequent aberrant DNA hypomethylation ( 100 ). Finally, phosphorylation of DNMT1 by protein kinase C (PKC) has been reported, but the target sites have not yet been identified ( 101 ).…”

TET2 stabilization by 14-3-3 binding to the phosphorylated Serine 99 is deregulated by mutations in cancer

“…S3a, b). 7 Importantly, we observed enriched co-localization of TET2 and nuclear 14-3-3 proteins after treatment with an AMPK activator, A769662 (Supplementary information, Fig. S3b, c).…”