Dataset Information

Amino Acids 563-566 of the Na+/H+ Exchanger Isoform 1 C-Terminal Cytosolic Tail Prevent Protein Degradation and Stabilize Protein Expression and Activity.

ABSTRACT: Isoform one of the mammalian Na+/H+ exchanger is a plasma membrane protein that is ubiquitously present in humans. It regulates intracellular pH through the removal of one intracellular proton in exchange for a single extracellular sodium. It consists of a 500 amino acid membrane domain plus a 315 amino acid, C-terminal tail. We examined amino acids of the C-terminal tail that are important in the targeting and activity of the protein. A previous study demonstrated that stop codon polymorphisms can result in decreased activity, expression, targeting and enhanced protein degradation. Here, we determine elements that are critical in these anomalies. A series of progressive deletions of the C-terminal tail demonstrated a progressive decrease in activity and targeting, though these remained until a final drop off with the deletion of amino acids 563-566. The deletion of the 562LIAGERS568 sequence or the alteration to the 562LAAAARS568 sequence caused the decreased protein expression, aberrant targeting, reduced activity and enhanced degradation of the Na+/H+ exchanger (NHE1) protein. The 562LIAGERS568 sequence bound to other regions of the C-terminal cytosolic domain. We suggest this region is necessary for the activity, targeting, stability, and expression of the NHE1 protein. The results define a new sequence that is important in maintenance of NHE1 protein levels and activity.

SUBMITTER: Li X

PROVIDER: S-EPMC7084640 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

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Amino Acids 563-566 of the Na+/H+ Exchanger Isoform 1 C-Terminal Cytosolic Tail Prevent Protein Degradation and Stabilize Protein Expression and Activity.

Li Xiuju X Dutta Debajyoti D Jung Martin M Zimmermann Richard R Fliegel Larry L

International journal of molecular sciences 20200303 5

Isoform one of the mammalian Na+/H+ exchanger is a plasma membrane protein that is ubiquitously present in humans. It regulates intracellular pH through the removal of one intracellular proton in exchange for a single extracellular sodium. It consists of a 500 amino acid membrane domain plus a 315 amino acid, C-terminal tail. We examined amino acids of the C-terminal tail that are important in the targeting and activity of the protein. A previous study demonstrated that sto ...[more]

PMID: 32138345

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Project description:Transmissible gastroenteritis virus (TGEV) is member of the family Coronaviridae and mainly causes acute diarrhea. TGEV infection is characterized by vomiting, watery diarrhea, and severe dehydration, resulting in high mortality rates in neonatal piglets. TGEV infection symptoms are related to an imbalance of sodium absorption in small intestinal epithelial cells; however, the etiology of sodium imbalance diarrhea caused by TGEV remains unclear. In this study, we performed transcriptomic analysis of intestinal tissues from infected and healthy piglets and observed that the expression of NHE3, encoding Na+/H+ exchanger 3 (NHE3), the main exchanger of electroneutral sodium in intestinal epithelial cells, was significantly reduced upon TGEV infection. We also showed that specific inhibition of intestinal NHE3 activity could lead to the development of diarrhea in piglets. Furthermore, we revealed an interaction between TGEV N protein and NHE3 near the nucleus. The binding of TGEV N to NHE3 directly affected the expression and activity of NHE3 on the cell surface and affected cellular electrolyte absorption, leading to diarrhea. Molecular docking and computer-aided screening techniques were used to screen for the blocker of the interaction between TGEV N and NHE3, which identified irinotecan. We then demonstrated that irinotecan was effective in relieving TGEV-induced diarrhea in piglets. These findings provide new insights into the mechanism of TGEV-induced sodium imbalance diarrhea and could lead to the design of novel antiviral strategies against TGEV. IMPORTANCE A variety of coronaviruses have been found to cause severe diarrhea in hosts, including TGEV; however, the pathogenic mechanism is not clear. Therefore, prompt determination of the mechanism and identification of efficient therapeutic agents are required, both for public health reasons and for economic development. In this study, we demonstrated that NHE3 is the major expressed protein of NHEs in the intestine, and its expression decreased by nearly 70% after TGEV infection. Also, specific inhibition of intestinal NHE3 resulted in severe diarrhea in piglets. This demonstrated that NHE3 plays an important role in TGEV-induced diarrhea. In addition, we found that TGEV N directly regulates NHE3 expression and activity through protein-protein interaction, which is essential to promote diarrhea. Molecular docking and other techniques demonstrated that irinotecan could block the interaction and diarrhea caused by TGEV. Thus, our results provide a basis for the development of novel therapeutic agents against TGEV and guidance for the development of drugs for other diarrhea-causing coronaviruses.

Dataset Information

Amino Acids 563-566 of the Na+/H+ Exchanger Isoform 1 C-Terminal Cytosolic Tail Prevent Protein Degradation and Stabilize Protein Expression and Activity.

Publications

Amino Acids 563-566 of the Na<sup>+</sup>/H<sup>+</sup> Exchanger Isoform 1 C-Terminal Cytosolic Tail Prevent Protein Degradation and Stabilize Protein Expression and Activity.

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