Proteomic analysis of β‐catenin activation in mouse liver by DIGE analysis identifies glucose metabolism as a new target of the Wnt pathway

Abstract

The Wnt/beta-catenin signaling pathway has been increasingly implicated in liver development and physiology. Aberrant activation of this pathway is one of the major genetic events observed during the process of human HCC development. To gain insight into the mechanism underlying beta-catenin action in the liver, we conducted a quantitative differential proteomic analysis using 2-D DIGE combined with MS, in mice with liver-specific deletion of Apc resulting in acute activation of beta-catenin signaling (Apc(KOliv) mice). We identified 94 protein spots showing differential expression between mutant Apc(KOliv) and control mice, corresponding to 56 individual proteins. Most of the proteins identified were associated with metabolic pathways, such as ammonia and glucose metabolism. Our analysis showed an increase in lactate dehydrogenase activity together with a downregulation of two mitochondrial ATPase subunits (ATP5a1 and ATP5b). These observations indicate that beta-catenin signaling may induce a shift in the glucose metabolism from oxidative phosphorylation to glycolysis, known as the "Warburg effect". Imaging with (18)F-fluoro-2-deoxy-D-glucose-positron emission tomography suggests that the specific metabolic reprogramming induced by beta-catenin in the liver does not imply the first step of glycolysis. This observation may explain why some HCCs are difficult to assess by fluoro-2-deoxy-D-glucose-positron emission tomography imaging.

Proteomic analysis reveals APC-dependent post translational modifications and identifies a novel regulator of β-catenin

“…The APC-dependent difference-protein isoform pairs do not require β-cat transcription Previous proteomics of APC mutant tissue identified a number of proteins with elevated levels, presumably resulting from the transcriptional activation of Wnt target genes via β-cat (Chafey et al, 2009;Hammoudi et al, 2013). In our analysis, only two of the APC-dependent difference-proteins displayed a total abundance change in the Apc2 mutant consistent with reduced protein stability (mRpS30 and Cbs/Tcp-1ζ, Fig.…”

“…In addition, Drosophila APC1 binds actin monomers, nucleates F-actin assembly (Jaiswal et al, 2013) and binds the microtubule plus-tip protein EB1 (Webb et al, 2009), like vertebrate APC. Previous studies have examined the global cellular consequence of APC disruption using RNA-seq and two-dimensional difference gel electrophoresis (2D-DIGE) proteomics (Chafey et al, 2009;Wu et al, 2012). However, the results of these studies reflect chronic changes due to the primary and downstream effects of ligand-independent Wnt target gene activation.…”

“…To address these gaps, we conducted a comparative proteomic analysis using 2D-DIGE in Drosophila embryos null for APC proteins and discovered a set of APC-dependent protein isoform changes due to PTMs. 2D-DIGE comparisons of livers isolated from wild-type and Apc knockout mice 7 days postknockout revealed significant protein abundance changes (Chafey et al, 2009). Many of these changes are likely to result from transcriptional activation by β-cat.…”

Wnt/Snail Signaling Regulates CytochromecOxidase and Glucose Metabolism

“…Although Wnt induces PC, it increased lactate production (Fig. 5), possibly due to an increase in LDH levels through b-catenin, which is activated in response to Wnt (30). Thus, pyruvate seems to be converted either to lactate by LDH or to oxaloacetate by PC (Supplementary Fig.…”

Emerging Roles of Cadmium and Heme Oxygenase in Type-2 Diabetes and Cancer Susceptibility

“…A role for Wnt/ β-catenin signalling in the glucose-sensing mechanism has been shown in macrophage cells (Anagnostou and Sheperd 2008), and its connection to heme catabolism needs to be explored. Proteomic analysis identified glucose metabolism in mouse liver as the target of β-catenin signalling pathway (Chafey et al 2009). Polymorphism in the β-catenin effector gene TCF7/L2 was associated with increased risk of type-2 diabetes (Tong et al 2009).…”