scholarly journals Cell Surface Expression of Human Ether-a-go-go-related Gene (hERG) Channels Is Regulated by Caveolin-3 Protein via the Ubiquitin Ligase Nedd4-2

2012 ◽  
Vol 287 (40) ◽  
pp. 33132-33141 ◽  
Author(s):  
Jun Guo ◽  
Tingzhong Wang ◽  
Xian Li ◽  
Heidi Shallow ◽  
Tonghua Yang ◽  
...  
Keyword(s):  
Cell Surface ◽  
Ubiquitin Ligase ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Related Gene ◽  
Herg Channels

scholarly journals Protein kinase C regulates organic anion transporter 1 through phosphorylating ubiquitin ligase Nedd4–2

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Zhou Yu ◽  
Chenchang Liu ◽  
Jinghui Zhang ◽  
Zhengxuan Liang ◽  
Guofeng You
Keyword(s):  
Protein Kinase C ◽  
Cell Surface ◽  
Ubiquitin Ligase ◽  
Organic Anion ◽  
Surface Expression ◽  
Organic Anion Transporter ◽  
Cell Surface Expression ◽  
Transport Activity ◽  
Kinase C ◽  
Anion Transporter

Abstract Background Organic anion transporter 1 (OAT1) is a drug transporter expressed on the basolateral membrane of the proximal tubule cells in kidneys. It plays an essential role in the disposition of numerous clinical therapeutics, impacting their pharmacological and toxicological properties. The activation of protein kinase C (PKC) is shown to facilitate OAT1 internalization from cell surface to intracellular compartments and thereby reducing cell surface expression and transport activity of the transporter. The PKC-regulated OAT1 internalization occurs through ubiquitination, a process catalyzed by a E3 ubiquitin ligase, neural precursor cell expressed developmentally down-regulated 4–2 (Nedd4–2). Nedd4–2 directly interacts with OAT1 and affects ubiquitination, expression and stability of the transporter. However, whether Nedd4–2 is a direct substrate for PKC-induced phosphorylation is unknown. Results In this study, we investigated the role of Nedd4–2 phosphorylation in the PKC regulation of OAT1. The results showed that PKC activation enhanced the phosphorylation of Nedd4–2 and increased the OAT1 ubiquitination, which was accompanied by a decreased OAT1 cell surface expression and transport function. And the effects of PKC could be reversed by PKC-specific inhibitor staurosporine. We further discovered that the quadruple mutant (T197A/S221A/S354A/S420A) of Nedd4–2 partially blocked the effects of PKC on Nedd4–2 phosphorylation and on OAT1 transport activity. Conclusions Our investigation demonstrates that PKC regulates OAT1 likely through direct phosphorylation of Nedd4–2. And four phosphorylation sites (T197, S221, S354, and S420) of Nedd4–2 in combination play an important role in this regulatory process.

scholarly journals A foldable CFTRΔF508 biogenic intermediate accumulates upon inhibition of the Hsc70–CHIP E3 ubiquitin ligase

2004 ◽  
Vol 167 (6) ◽  
pp. 1075-1085 ◽  
Author(s):  
J. Michael Younger ◽  
Hong-Yu Ren ◽  
Liling Chen ◽  
Chun-Yang Fan ◽  
Andrea Fields ◽  
...  
Keyword(s):  
Cystic Fibrosis ◽  
Cell Surface ◽  
Ubiquitin Ligase ◽  
E3 Ubiquitin Ligase ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Folding Defect ◽  
Cellular Components ◽  
Soluble State

CFTRΔF508 exhibits a correctable protein-folding defect that leads to its misfolding and premature degradation, which is the cause of cystic fibrosis (CF). Herein we report on the characterization of the CFTRΔF508 biogenic intermediate that is selected for proteasomal degradation and identification of cellular components that polyubiquitinate CFTRΔF508. Nonubiquitinated CFTRΔF508 accumulates in a kinetically trapped, but folding competent conformation, that is maintained in a soluble state by cytosolic Hsc70. Ubiquitination of Hsc70-bound CFTRΔF508 requires CHIP, a U box containing cytosolic cochaperone. CHIP is demonstrated to function as a scaffold that nucleates the formation of a multisubunit E3 ubiquitin ligase whose reconstituted activity toward CFTR is dependent upon Hdj2, Hsc70, and the E2 UbcH5a. Inactivation of the Hsc70–CHIP E3 leads CFTRΔF508 to accumulate in a nonaggregated state, which upon lowering of cell growth temperatures, can fold and reach the cell surface. Inhibition of CFTRΔF508 ubiquitination can increase its cell surface expression and may provide an approach to treat CF.

scholarly journals The HECT ubiquitin ligase AIP4 regulates the cell surface expression of select TRP channels

2006 ◽  
Vol 25 (24) ◽  
pp. 5659-5669 ◽  
Author(s):  
Tomasz Wegierski ◽  
Kerstin Hill ◽  
Michael Schaefer ◽  
Gerd Walz
Keyword(s):  
Cell Surface ◽  
Ubiquitin Ligase ◽  
Trp Channels ◽  
Surface Expression ◽  
Cell Surface Expression

Role of glycosylation in cell surface expression and stability of HERG potassium channels

2002 ◽  
Vol 283 (1) ◽  
pp. H77-H84 ◽  
Author(s):  
Qiuming Gong ◽  
Corey L. Anderson ◽  
Craig T. January ◽  
Zhengfeng Zhou
Keyword(s):  
Cell Surface ◽  
Protein Trafficking ◽  
Surface Expression ◽  
Site Directed Mutagenesis ◽  
Herg Channel ◽  
Cell Surface Expression ◽  
Delayed Rectifier ◽  
Channel Stability ◽  
Herg Channels

The human ether-à-go-go-related gene (HERG) encodes the pore-forming subunit of the rapidly activating delayed rectifier potassium channel in the heart. We previously showed that HERG channel protein is modified by N-linked glycosylation. HERG protein sequence contains two extracellular consensus sites for N-linked glycosylation (N598, N629). In this study, we used the approaches of site-directed mutagenesis and biochemical modification to inhibit N-linked glycosylation and studied the role of glycosylation in the cell surface expression and turnover of HERG channels. Our results show that N598 is the only site for N-linked glycosylation and that glycosylation is not required for the cell surface expression of functional HERG channels. In contrast, N629 is not used for glycosylation, but mutation of this site (N629Q) causes a protein trafficking defect, which results in its intracellular retention. Pulse-chase experiments show that the turnover rate of nonglycosylated HERG channel is faster than that of the glycosylated form, suggesting that N-linked glycosylation plays an important role in HERG channel stability.

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