Degree Name

PhD (Doctor of Philosophy)

Program

Biomedical Sciences

Date of Award

5-2016

Committee Chair or Co-Chairs

Deling Yin

Committee Members

Alok Agrawal, Balvin H. Chua, Dennis M. Defoe, Donald B. Hoover

Abstract

β-arrestin2, previously recognized as a facilitator for G-protein associated 7 TMR desensitization/ internalization, has now been appreciated as an independent signal transducer that regulates multiple cellular responses including inflammation. Cecal ligation and puncture procedure (CLP) induced septic shock is an acute inflammatory response characterized by uncontrolled systemic inflammation. Myocardial ischemia/reperfusion is a chronic sterilize inflammation that requires the reaction of macrophages, fibroblasts and cardiac stem cells for regeneration and remodeling of the infarcted myocardium. Restrained chronic stress is an immune suppression model in which the inactivation of macrophages may be involved. Here we showed β-arrestin2 overexpression inhibited CLP-induced heart dysfunction in septic shock, stabilized the cardiovascular system, and eventually promoted survival. Inhibition of the activation of p38 that downstream of the IL-6 pathway may be a key regulatory target for β-arrestin2. To rescue cardiomyocytes from ischemia and reperfusion injury, Sca-1+ CSC from Wide-type or β-arrestin2 Knockout mice were delivered to the risked area before reperfusion; β-arrestin2 was shown to be a required factor and a promoter for the differentiation of the cardiac stem cells. A β-arrestin2/miR-155/GSK3β pathway was identified in this study. TLR-9 is an important part of the innate immune system which has been shown to be regulated by β-arrestin2 in various inflammatory models. Here we found, the immune suppression induced by restrained stress is mediated by Toll-like receptor 9 (TLR-9). TLR-9 facilitated the elevation of IL-1β, IL-10 and IL-17 levels in serum and decrease of the levels of plasma IFN-γ. Furthermore, macrophage apoptosis was alleviated in TLR-9 deficiency mice. In summary, β-arrestin2 and associated proteins like TLR-9 are important regulators of the immune response in a variety of disease conditions. Therapeutic strategies should be generated to balance the inflammation and anti-inflammation response by modulating β-arrestin2 expression and functions.

Document Type

Dissertation - Withheld

Copyright

Copyright by the authors.

Available for download on Saturday, October 31, 2020

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