Regulation of the nuclear localization of the human Nedd4-related WWP1 protein by Notch

Abstract

Nedd4 family ubiquitin ligases regulate trafficking and degradation of numerous target substrates in different cellular compartments, including at the plasma membrane, in endosomes, in the secretory pathway and in the nucleus. WWP1 is a Nedd4 family protein closely related to mouse Itch and Drosophila Su(dx), both of which have been shown to regulate the Notch receptor. To investigate the possibility that WWP1 is also associated with Notch signalling we coexpressed human Notch1 and WWP1 in mouse myoblast cells. We found that WWP1 could localize to both the nucleus and cytoplasm in a context dependent manner. Coexpression of human Notch1 (hN1) depleted WWP1 from the nucleus to colocalise with hN1 in early endosomes, dependent on the presence of the C-terminal HECT domain. Furthermore we found that full-length expressed WWP1 could interact in vitro with the cytoplasmic domain of human Notch1. The Notch receptor has multiple roles in development, mediating a short-range signal that controls cell fate and pattern formation. The canonical Notch signal involves proteolytic release of the soluble Notch intracellular domain and the activation by the latter of the transcription factor Suppressor of Hairless/CBF-1 in the nucleus. This pathway does not however account for all of the activity of Notch. The ability of Notch to regulate the nuclear localization of WWP1 suggests a possible alternative mechanism by which Notch may communicate a signal to the nucleus. Drosophila Notch similarly regulated the nuclear localization of the Drosophila Nedd4 family protein, Suppressor of deltex, implying conservation of this mechanism during evolution.

Overexpression of WWP1 is associated with the estrogen receptor and insulin‐like growth factor receptor 1 in breast carcinoma

“…2b). Although WWP1 has been previously reported to localize to the cytoplasmic membrane, cytoplasmic compartments and nucleus by immunofluorescence staining, 17,33,34 we observed that WWP1 predominantly localizes to the cytoplasm by IHC. WWP1 is strongly overexpressed in some but not all invasive breast carcinomas.…”

The Nedd4-like family of E3 ubiquitin ligases and cancer

“…The C2 domain is necessary but not sufficient for endosomal localization. Wwp1 has been detected on early endosomes in the murine skeletal muscle cell line C2C12 [156]. Interestingly, Nedd4 is translocated to mitochondria upon IGF-1R activation, raising the possibility that Nedd4 may mediate the anti-apoptotic signaling of the IGF-1R [157].…”

WWP1: a versatile ubiquitin E3 ligase in signaling and diseases

“…It is worth pointing out that the exogenous WWP1 protein is predominantly localized in cytoplasmic punctate membrane structures and occasionally localized in the nucleus [11]. Flasza et al [26] demonstrated that the exogenous WWP1 protein is localized to the early endosome in C2C12 murine skeletal muscle-derived myoblast cells. By immunohistochemistry (IHC), Huu et al [24] detected both nuclear and cytoplasmic endogenous WWP1 protein expression in breast tumors.…”

“…In non-differentiated C2C12 cells, WWP1 is distributed in both the nucleus and cytoplasm. When the cells were induced to differentiate, the localization of WWP1 was exclusively in the cytoplasm [26].…”