WNK1 regulates uterine homeostasis and its ability to support pregnancy

Abstract

21WNK1 is critical for uterine function as a mediator of stromal cell decidualization in vitro. 22 Here, we employed a mouse model with conditional WNK1 ablation from the female 23 reproductive tract to define its in vivo role in uterine biology. Loss of WNK1 altered uterine 24 morphology, causing endometrial epithelial hyperplasia, adenomyosis and a delay in 25 embryo implantation, ultimately resulting in compromised fertility. Mechanistic 26 investigations through transcriptomic and proteomic approaches uncovered the 27 regulatory role of WNK1 in controlling the PP2A-AKT-FOXO1 signaling axis. We show 28 that WNK1 interacts directly with PPP2R1A, which is crucial for PP2A phosphatase 29 activity. PP2A phosphatase in turn dephosphorylates AKT, thereby reducing its inhibitory 30 effect on FOXO1. This permits the nuclear entry of FOXO1 to transcriptionally regulate 31 implantation-associated genes. Our findings revealed a novel function of WNK1 in 32 regulating AKT-FOXO1 post-translational modification, and demonstrated that this 33 signaling pathway is critical in normal uterine physiology and pregnancy. 34 35 36 37 38 physiological functions, the underlying cellular components regulated by WNK1 may share 62 similarity between the different tissues. 63 64Despite its ubiquitous expression pattern, WNK1's role in organs other than those described 65 above remain unexplored. Given the role of WNK1 in regulating uterine stromal cell biology in 66 vitro, we hypothesized that WNK1 is essential in regulating uterine functions. To test this idea, we 67 established a conditional uterine WNK1 ablated mouse model, which resulted in severely 68 compromised fertility. We demonstrated that WNK1 is critical in maintaining uterine morphology, 69regulating epithelial proliferation and permitting appropriate embryo implantation. Additionally, we 70 defined the molecular mechanism through both transcriptomic and proteomic approaches to show 71 that the WNK1 signaling cascade begins by its direct interaction with the scaffold subunit of the 72 phosphatase complex PP2A, PPP2R1A. This interaction stabilized PP2A which prevented 73 unregulated AKT phosphorylation, ultimately alleviating AKT's inhibitory effect on FOXO1 nuclear 74 localization, an indispensable mediator of implantation 16 . 75 76 5 RESULTS 77 78 WNK1 is expressed in the uterus during early pregnancy in both humans and mice 79WNK1 expression was examined by immunohistochemistry in human endometrium during the 80 proliferative and mid-secretory phases as well as in the peri-implantation uterus of mice. In 81 humans, WNK1 is expressed in both the epithelial and stromal cells during the proliferative and 82 mid-secretory phases (Fig. 1.A). Similarly in mice, WNK1 is expressed during and after 83 implantation on gestation days (GDs) 4.5 and 5.5 (Fig. 1.B). These findings support the in vivo 84 involvement of WNK1 in regulating functions of the female reproductive tract. 85 86 WNK1 ablation altered uterine morphology and microenvironment 87To examine WNK1's function in the ...

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“…Such disruption could potentially affect the timing of embryos' arrival in the uterus at the window of receptivity. Embryos missing the window of receptivity may still proceed to implantation but often end up with pregnancy loss (81). Another potential cause of the pregnancy loss phenotype is the spiral vasculature remodeling (82).…”

Targeting Akt in cancer for precision therapy

“…Aldolase B facilitates the recruiting of PP2A to phosphorylated Akt and then promotes Akt dephosphorylation independent of the enzyme activity of adolase B [ 119 ]. Furthermore, the stability of PP2A subunits is enhanced by WNK lysine-deficient protein kinase 1, which interacts with protein phosphatase 2 scaffold subunit alpha [ 120 ]. However, Akt may reciprocally inactivate PP2A via microtubule-associated serine/threonine kinase-like (MASTL) [ 121 ].…”