scholarly journals Gαs protein binds ubiquitin to regulate epidermal growth factor receptor endosomal sorting

2017 ◽  
Vol 114 (51) ◽  
pp. 13477-13482 ◽  
Author(s):  
Xuezhi Li ◽  
Danny Létourneau ◽  
Brian Holleran ◽  
Richard Leduc ◽  
Pierre Lavigne ◽  
...  
Keyword(s):  
Epidermal Growth Factor Receptor ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Cellular Response ◽  
Growth Factor Receptor ◽  
Fine Tuning ◽  
Lysosomal Degradation ◽  
Endosomal Sorting ◽  
Epidermal Growth ◽  
G Protein Coupled

The Gαs subunit is classically involved in the signal transduction of G protein-coupled receptors (GPCRs) at the plasma membrane. Recent evidence has revealed noncanonical roles for Gαs in endosomal sorting of receptors to lysosomes. However, the mechanism of action of Gαs in this sorting step is still poorly characterized. Here, we report that Gαs interacts with ubiquitin to regulate the endosomal sorting of receptors for lysosomal degradation. We reveal that the N-terminal extremity of Gαs contains a ubiquitin-interacting motif (UIM), a sorting element usually found in the endosomal sorting complex required for transport (ESCRT) machinery responsible for sorting ubiquitinated receptors into intraluminal vesicles (ILVs) of multivesicular bodies (MVBs). Mutation of the UIM in Gαs confirmed the importance of ubiquitin interaction for the sorting of epidermal growth factor receptor (EGFR) into ILVs for lysosomal degradation. These findings demonstrate a role for Gαs as an integral component of the ubiquitin-dependent endosomal sorting machinery and highlight the dual role of Gαs in receptor trafficking and signaling for the fine-tuning of the cellular response.

scholarly journals The Ubiquitin-like Protein PLIC-2 Is a Negative Regulator of G Protein-coupled Receptor Endocytosis

2008 ◽  
Vol 19 (3) ◽  
pp. 1252-1260 ◽  
Author(s):  
Elsa-Noah N'Diaye ◽  
Aylin C. Hanyaloglu ◽  
Kimberly K. Kajihara ◽  
Manojkumar A. Puthenveedu ◽  
Ping Wu ◽  
...  
Keyword(s):  
Epidermal Growth Factor Receptor ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
G Protein ◽  
Growth Factor Receptor ◽  
Negative Regulator ◽  
Regulatory Function ◽  
Receptor Endocytosis ◽  
Epidermal Growth ◽  
G Protein Coupled

The activity of many signaling receptors is regulated by their endocytosis via clathrin-coated pits (CCPs). For G protein-coupled receptors (GPCRs), recruitment of the adaptor protein arrestin to activated receptors is thought to be sufficient to drive GPCR clustering in CCPs and subsequent endocytosis. We have identified an unprecedented role for the ubiquitin-like protein PLIC-2 as a negative regulator of GPCR endocytosis. Protein Linking IAP to Cytoskeleton (PLIC)-2 overexpression delayed ligand-induced endocytosis of two GPCRs: the V2 vasopressin receptor and β-2 adrenergic receptor, without affecting endocytosis of the transferrin or epidermal growth factor receptor. The closely related isoform PLIC-1 did not affect receptor endocytosis. PLIC-2 specifically inhibited GPCR concentration in CCPs, without affecting membrane recruitment of arrestin-3 to activated receptors or its cellular levels. Depletion of cellular PLIC-2 accelerated GPCR endocytosis, confirming its regulatory function at endogenous levels. The ubiquitin-like domain of PLIC-2, a ligand for ubiquitin-interacting motifs (UIMs), was required for endocytic inhibition. Interestingly, the UIM-containing endocytic adaptors epidermal growth factor receptor protein substrate 15 and Epsin exhibited preferential binding to PLIC-2 over PLIC-1. This differential interaction may underlie PLIC-2 specific effect on GPCR endocytosis. Identification of a negative regulator of GPCR clustering reveals a new function of ubiquitin-like proteins and highlights a cellular requirement for exquisite regulation of receptor dynamics.

Neoadjuvant Trastuzumab Induces Apoptosis in Primary Breast Cancers

2005 ◽  
Vol 23 (11) ◽  
pp. 2460-2468 ◽  
Author(s):  
Syed K. Mohsin ◽  
Heidi L. Weiss ◽  
M. Carolina Gutierrez ◽  
Gary C. Chamness ◽  
Rachel Schiff ◽  
...  
Keyword(s):  
Epidermal Growth Factor Receptor ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Cellular Response ◽  
Single Agent ◽  
Locally Advanced ◽  
Growth Factor Receptor ◽  
Breast Cancers ◽  
Her 2 ◽  
Epidermal Growth

Purpose Greater understanding of the cellular response in trastuzumab-treated patients will provide insight into the clinical management of patients. Patients and Methods We performed a neoadjuvant trial in 35 patients with locally advanced HER-2/neu overexpressing breast cancers who received weekly trastuzumab given as a single agent for the first 3 weeks, followed by a combination of trastuzumab and docetaxel for 12 weeks before surgery. Sequential core biopsies were taken at baseline and within weeks 1 and 3 after the first dose of trastuzumab. Clinical response to trastuzumab was assessed by tumor measurements on day 22 before chemotherapy. Core biopsies were assessed by immunohistochemistry for cell cycle and proliferation (Ki67, p27, phosphorylated [p] -MAPK), apoptosis and survival (apoptotic index, p-Akt), epidermal growth factor receptor, and total and p-HER-2. Results There was early tumor regression with a median decrease of −20.0% (range. 0% to 60.4%) after only 3 weeks of trastuzumab, and eight patients (23%) had a partial response. Consistent with the clinical regressions, apoptosis was significantly induced (median increase from 3.5% to 4.7%; P = .006) within week 1, a 35% increase above baseline. No significant change in epidermal growth factor receptor score was observed in week 1, without changes in total or p-HER-2 expression. Tumors with high baseline Ki67 were less likely to respond (P = .02). Conclusion In primary breast cancers, trastuzumab substantially induces apoptosis, providing a molecular explanation for both its therapeutic efficacy and its successful combination with cytotoxic chemotherapy.

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