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E4orf1: A Novel Ligand That Improves Glucose Disposal in Cell Culture

Reducing dietary fat intake and excess adiposity, the cornerstones of behavioral treatment of insulin resistance(IR), are marginally successful over the long term. Ad36, a human adenovirus, offers a template to improve IR, independent of dietary fat intake or adiposity. Ad36 increases cellular gluco...

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Autores principales: Dhurandhar, Emily J., Dubuisson, Olga, Mashtalir, Nazar, Krishnapuram, Rashmi, Hegde, Vijay, Dhurandhar, Nikhil V.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2011
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3160302/
https://www.ncbi.nlm.nih.gov/pubmed/21886789
http://dx.doi.org/10.1371/journal.pone.0023394
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author Dhurandhar, Emily J.
Dubuisson, Olga
Mashtalir, Nazar
Krishnapuram, Rashmi
Hegde, Vijay
Dhurandhar, Nikhil V.
author_facet Dhurandhar, Emily J.
Dubuisson, Olga
Mashtalir, Nazar
Krishnapuram, Rashmi
Hegde, Vijay
Dhurandhar, Nikhil V.
author_sort Dhurandhar, Emily J.
collection PubMed
description Reducing dietary fat intake and excess adiposity, the cornerstones of behavioral treatment of insulin resistance(IR), are marginally successful over the long term. Ad36, a human adenovirus, offers a template to improve IR, independent of dietary fat intake or adiposity. Ad36 increases cellular glucose uptake via a Ras-mediated activation of phosphatidyl inositol 3-kinase(PI3K), and improves hyperglycemia in mice, despite a high-fat diet and without reducing adiposity. Ex-vivo studies suggest that Ad36 improves hyperglycemia in mice by increasing glucose uptake by adipose tissue and skeletal muscle, and by reducing hepatic glucose output. It is impractical to use Ad36 for therapeutic action. Instead, we investigated if the E4orf1 protein of Ad36, mediates its anti-hyperglycemic action. Such a candidate protein may offer an attractive template for therapeutic development. Experiment-1 determined that Ad36 ‘requires’ E4orf1 protein to up-regulate cellular glucose uptake. Ad36 significantly increased glucose uptake in 3T3-L1 preadipocytes, which was abrogated by knocking down E4orf1 with siRNA. Experiment-2 identified E4orf1 as ‘sufficient’ to up-regulate glucose uptake. 3T3-L1 cells that inducibly express E4orf1, increased glucose uptake in an induction-dependent manner, compared to null vector control cells. E4orf1 up-regulated PI3K pathway and increased abundance of Ras–the obligatory molecule in Ad36-induced glucose uptake. Experiment-3: Signaling studies of cells transiently transfected with E4orf1 or a null vector, revealed that E4orf1 may activate Ras/PI3K pathway by binding to Drosophila discs-large(Dlg1) protein. E4orf1 activated total Ras and, particularly the H-Ras isoform. By mutating the PDZ domain binding motif(PBM) of E4orf1, Experiment-4 showed that E4orf1 requires its PBM to increase Ras activation or glucose uptake. Experiment-5: In-vitro, a transient transfection by E4orf1 significantly increased glucose uptake in preadipocytes, adipocytes, or myoblasts, and reduced glucose output by hepatocytes. Thus, the highly attractive anti-hyperglycemic effect of Ad36 is mirrored by E4orf1 protein, which may offer a novel ligand to develop anti-hyperglycemic drugs.
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spelling pubmed-31603022011-08-30 E4orf1: A Novel Ligand That Improves Glucose Disposal in Cell Culture Dhurandhar, Emily J. Dubuisson, Olga Mashtalir, Nazar Krishnapuram, Rashmi Hegde, Vijay Dhurandhar, Nikhil V. PLoS One Research Article Reducing dietary fat intake and excess adiposity, the cornerstones of behavioral treatment of insulin resistance(IR), are marginally successful over the long term. Ad36, a human adenovirus, offers a template to improve IR, independent of dietary fat intake or adiposity. Ad36 increases cellular glucose uptake via a Ras-mediated activation of phosphatidyl inositol 3-kinase(PI3K), and improves hyperglycemia in mice, despite a high-fat diet and without reducing adiposity. Ex-vivo studies suggest that Ad36 improves hyperglycemia in mice by increasing glucose uptake by adipose tissue and skeletal muscle, and by reducing hepatic glucose output. It is impractical to use Ad36 for therapeutic action. Instead, we investigated if the E4orf1 protein of Ad36, mediates its anti-hyperglycemic action. Such a candidate protein may offer an attractive template for therapeutic development. Experiment-1 determined that Ad36 ‘requires’ E4orf1 protein to up-regulate cellular glucose uptake. Ad36 significantly increased glucose uptake in 3T3-L1 preadipocytes, which was abrogated by knocking down E4orf1 with siRNA. Experiment-2 identified E4orf1 as ‘sufficient’ to up-regulate glucose uptake. 3T3-L1 cells that inducibly express E4orf1, increased glucose uptake in an induction-dependent manner, compared to null vector control cells. E4orf1 up-regulated PI3K pathway and increased abundance of Ras–the obligatory molecule in Ad36-induced glucose uptake. Experiment-3: Signaling studies of cells transiently transfected with E4orf1 or a null vector, revealed that E4orf1 may activate Ras/PI3K pathway by binding to Drosophila discs-large(Dlg1) protein. E4orf1 activated total Ras and, particularly the H-Ras isoform. By mutating the PDZ domain binding motif(PBM) of E4orf1, Experiment-4 showed that E4orf1 requires its PBM to increase Ras activation or glucose uptake. Experiment-5: In-vitro, a transient transfection by E4orf1 significantly increased glucose uptake in preadipocytes, adipocytes, or myoblasts, and reduced glucose output by hepatocytes. Thus, the highly attractive anti-hyperglycemic effect of Ad36 is mirrored by E4orf1 protein, which may offer a novel ligand to develop anti-hyperglycemic drugs. Public Library of Science 2011-08-23 /pmc/articles/PMC3160302/ /pubmed/21886789 http://dx.doi.org/10.1371/journal.pone.0023394 Text en Dhurandhar et al. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Dhurandhar, Emily J.
Dubuisson, Olga
Mashtalir, Nazar
Krishnapuram, Rashmi
Hegde, Vijay
Dhurandhar, Nikhil V.
E4orf1: A Novel Ligand That Improves Glucose Disposal in Cell Culture
title E4orf1: A Novel Ligand That Improves Glucose Disposal in Cell Culture
title_full E4orf1: A Novel Ligand That Improves Glucose Disposal in Cell Culture
title_fullStr E4orf1: A Novel Ligand That Improves Glucose Disposal in Cell Culture
title_full_unstemmed E4orf1: A Novel Ligand That Improves Glucose Disposal in Cell Culture
title_short E4orf1: A Novel Ligand That Improves Glucose Disposal in Cell Culture
title_sort e4orf1: a novel ligand that improves glucose disposal in cell culture
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3160302/
https://www.ncbi.nlm.nih.gov/pubmed/21886789
http://dx.doi.org/10.1371/journal.pone.0023394
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