Mitigation of carbon tetrachloride‐induced hepatic injury by methylene blue, a repurposed drug, is mediated by dual inhibition of GSK3β downstream of PKA. (June 2014)

• Record Type: Journal Article
• Authors: Wu, Hong Min; Lee, Chan Gyu; Hwang, Se Jin; Kim, Sang Geon
• Is Part Of: British journal of pharmacology. Volume 171:Number 11(2014:Jun.)
• Page Start: 2790
• Page End: 2802
• Publication Date: 2014-06
• Subjects: Pharmacology -- Periodicals; Chemotherapy -- Periodicals; Drug Therapy -- Periodicals; Pharmacology -- Periodicals; 615.1
• DOI: 10.1111/bph.12637
• Languages: English
• ISSNs: 0007-1188

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <sec id="bph12637-sec-0001" sec-type="section"> <title>Background and Purpose</title> <p>Methylene blue (MB) has recently been considered for new therapeutic applications. In this study, we investigated whether MB has antioxidant and mitochondria‐protecting effects and can prevent the development of toxicant‐induced hepatitis. In addition, we explored the underlying basis of its effects.</p> </sec> <sec id="bph12637-sec-0002" sec-type="section"> <title>Experimental Approach</title> <p>Blood biochemistry and histopathology were assessed in mice injected with CCl<sub>4</sub> (0.5 mL·kg<sup>−1</sup>) following MB administration (3 mg·kg<sup>−1</sup>·day<sup>−1</sup>, 3 days). Immunoblottings were performed to measure protein levels. Cell survival, H<sub>2</sub>O<sub>2</sub>, and mitochondrial superoxide and membrane permeability transition were determined in HepG2 cells.</p> </sec> <sec id="bph12637-sec-0003" sec-type="section"> <title>Key Results</title> <p>MB protected cells from oxidative stress induced by arachidonic acid plus iron; it restored GSH content and decreased the production of H<sub>2</sub>O<sub>2</sub>. It consistently attenuated mitochondria dysfunction, as indicated by inhibition of superoxide production and mitochondrial permeability transition. MB inhibited glycogen synthase kinase‐3β (GSK3β) and protected the liver against CCl<sub>4</sub>. Using siRNA, the inhibition of GSK3β was shown to depend on AMPK. MB increased the activation of AMPK <italic>in vitro</italic> (3–24 h) and <italic>in vivo</italic>. MB also increased the phosphorylation of liver kinase B1 (LKB1) via cAMP‐dependent PKA. SiRNA knockdown of LKB1 eliminated phosphorylation of AMPK and inhibited MB activation of AMPK. In addition, MB treatment (≤1 h) facilitated PKA‐mediated GSK3β serine phosphorylation independently of AMPK.</p> </sec> <sec id="bph12637-sec-0004" sec-type="section"> <title>Conclusions and Implications</title> <p>MB has antioxidant and mitochondria‐protecting effects and protects the liver from toxicants, which results from the dual inhibition of GSK3β by AMPK downstream of PKA‐activated LKB1, and PKA itself. Our findings reveal a novel pharmacological effect of MB and its molecular basis.</p> </sec> </abstract>