Prolyl hydroxylase 3 stabilizes the p53 tumor suppressor by inhibiting the p53–MDM2 interaction in a hydroxylase-independent manner

Abstract

Prolyl hydroxylase 3 (PHD3) has initially been reported to hydroxylase hypoxia-inducible factor α (HIFα) and mediate HIFα degradation. More recent studies have shown that, in addition to HIFα, PHD3 has also other substrates. Moreover, pHD3 is believed to act as a tumor suppressor, but the underlying mechanism remains to be elucidated. Here, we demonstrate that PHD3 stabilizes p53 in a hydroxylase-independent manner. We found that PHD3 overexpression increases and PHD3 knockdown decreases p53 levels. Mechanistically, PHD3 bound MDM2 proto-oncogene (MDM2) and prevented MDM2 from interacting with p53, thereby inhibiting MDM2-mediated p53 degradation. Interestingly, we found that PHD3 overexpression could enhance p53 in the presence of the prolyl hydroxylase inhibitor dimethyloxalylglycine, and the prolyl hydroxylase activity-deficient variant PHD3-H196A also inhibited the p53-MDM2 interaction and stabilized p53. Genetic ablation of PHD3 decreased p53 protein levels in mice intestinal epithelial cells, but a genetic knockin of PHD3-H196A did not affect p53 protein levels in vivo. These results suggest that the prolyl hydroxylase activity of PHD3 is dispensable for its ability to stabilize p53. We found that both PHD3 and PHD3-H196A suppress the expression of the stem cell-associated gene NANOG and inhibited the properties of colon cancer stem cells through p53. Our results reveal an additional critical mechanism underlying the regulation of p53 expression and highlight that PHD3 plays a role in the suppression of colon cancer cell stemness in a hydroxylase-independent manner.

RETRACTED: Long noncoding RNA TUG1 facilitates cell ovarian cancer progression through targeting MiR‐29b‐3p/MDM2 axis

“…It has been reported that MDM2 involves in a negative regulatory loop between p53 and MDM2. MDM2 plays as an oncogene through negatively regulating the expression and activation of p53 (Xu et al, 2019; Zhang et al, 2019). MDM2 is a primary regulator of p53, p53 is well known as a crucial tumor suppressor in cancer through initiating cell cycle arrest, cell apoptosis, and promotes cancer cell senescence (Ning et al, 2019).…”

“…However, the function and the underlying molecular mechanism of TUG1 in OC were largely unknown. MDM2 is a well-known oncogene that is significantly overexpressed in a variety of cancers Xu et al, 2019). MDM2 gene is cloned from double minute, which is an abnormal chromosome and located in human chromosome 12q14.3-q15 and is a target gene of p53.…”

“…MDM2 is a well‐known oncogene that is significantly overexpressed in a variety of cancers (Liu, Wang, Wang, et al, 2019; Xu et al, 2019). MDM2 gene is cloned from double minute, which is an abnormal chromosome and located in human chromosome 12q14.3‐q15 and is a target gene of p53.…”

Understanding the Oxygen-Sensing Pathway and Its Therapeutic Implications in Diseases

“…Rodriguez et al 44 then demonstrated that p53 can be hydroxylated by PHD3/ EGLN3 at Pro359, which increases p53 stability by enhancing its ubiquitination by ubiquitin specific peptidase 7/10 (USP7/10). Interestingly, PHD3/EGLN3 also stabilizes p53 in a hydroxylase-independent manner, 45 suggesting a more complicated regulation network that deserves further investigation. Other important proteins that were subjected to PHD-mediated prolyl hydroxylation include I-kappaB kinase b (IKKb), mitogen-activated protein kinase 6 (MAPK6), dual-specificity tyrosine phosphorylation-regulated kinase 1A/1B (DYRK1A/B), N-myc downstreamregulated gene 3 (NDRG3), EPO receptor, and zinc fingers and homeoboxes 2 (ZHX2) and were therefore involved in the oxygen system and showed linkage with diseases.…”

Zebrafish phd3 Negatively Regulates Antiviral Responses via Suppression of Irf7 Transactivity Independent of Its Prolyl Hydroxylase Activity

“…Given a well-defined proline hydroxylase, phd3 modifies its target function through its enzymatic activity (3,5,6,16,19). To determine whether the suppressive role of phd3 on irf7 depended on its hydroxylase activity, we made two enzymatic-deficient mutants of phd3, Myc-phd3-HD142/144AA, and Myc-phd3-H203A and examined their effects on irf7 activity by promoter assays (16,19). These two enzymatic-deficient mutants had no obvious effect on the activity of the HRE reporter induced by either hif-1aa or hif-2aa (Supplemental Fig.…”