Over-expression of insulin-response element binding protein-1 (IRE-BP1) in mouse pancreatic islets increases expression of RACK1 and TCTP: Beta cell markers of high glucose sensitivity.

Abstract

BACKGROUND:

A targeted analysis of the 50kDa C-terminal fragment of insulin-response element binding protein-1 (IRE-BP1) activation of target genes through the insulin receptor substrate receptor/PI-3 kinase/Akt pathway has been demonstrated for the insulin growth factor-1 receptor. The broader effects of 50kDa C-terminal IRE-BP1 fragment over-expression on protein abundance in pancreatic islet beta cells have not been determined.

RESULTS:

Liquid-chromatography coupled to tandem mass spectrometry (LC-MS/MS) analyses of replicate lysates of pancreatic islets isolated from background strain animals and transgenic animals, overexpressing IRE-BP1 in pancreatic islet beta cells, demonstrated statistically significant increases in the expression of proteins involved in protein synthesis, endoplasmic reticulum (ER) stress and scaffolding proteins important for protein kinase C signaling; some of which were confirmed by immunoblot analyses. Bioinformatic analysis of protein expression network patterns suggested IRE-BP1 over-expression leads to protein expression patterns indicative of activation of functional protein networks utilized for protein post-translational modification, protein folding, and protein synthesis. Co-immunoprecipitation experiments demonstrate a novel interaction between two differentially regulated proteins receptor for activated protein kinase C (RACK1) and translationally controlled tumor protein (TCTP).

CONCLUSIONS:

Proteomic analysis of IRE-BP1 over-expression in pancreatic islet beta cells suggest IRE-BP1 (a) directly or indirectly through establishing hyperglycemia results in increased expression of ribosomal proteins and markers of ER stress and (b) leads to the enhanced and previously un-described interaction of RACK1 and TCTP.

SIGNIFICANCE:

This study identified C-terminal 50kDa domain of IRE-BP1 over-expression results in increased markers of ER-stress and a novel interaction between the scaffolding proteins RACK1 and TCTP.

• Authors: Betty C Villafuerte, Michelle T Barati, Madhavi J Rane, Susan Isaacs, Ming Li, Daniel W Wilkey, Michael L Merchant
• Journal: Biochimica et biophysica acta. Proteins and proteomics (Biochim Biophys Acta Proteins Proteom) Vol. 1865 Issue 2 Pg. 186-194 (Feb 2017) ISSN: 1570-9639 [Print] Netherlands
• PMID: 27816562 (Publication Type: Journal Article)
• Copyright: Copyright © 2016 Elsevier B.V. All rights reserved.

Chemical References

• Biomarkers
• Biomarkers, Tumor
• Insulin
• Neuropeptides
• RACK1 protein, mouse
• Receptors for Activated C Kinase
• Tpt1 protein, mouse
• Tumor Protein, Translationally-Controlled 1
• Protein Kinase C
• Iron Regulatory Protein 1
• Glucose

Topics

• Animals
• Biomarkers (metabolism)
• Biomarkers, Tumor (metabolism)
• Endoplasmic Reticulum Stress (physiology)
• Glucose (metabolism)
• Hyperglycemia
• Insulin (metabolism)
• Insulin-Secreting Cells (metabolism)
• Iron Regulatory Protein 1 (metabolism)
• Islets of Langerhans (metabolism)
• Mice
• Neuropeptides (metabolism)
• Protein Kinase C (metabolism)
• Protein Processing, Post-Translational (physiology)
• Proteomics (methods)
• Receptors for Activated C Kinase
• Response Elements (physiology)
• Tumor Protein, Translationally-Controlled 1