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1.  Inhibition of galectin-3 reduces atherosclerosis in apolipoprotein E-deficient mice 
Glycobiology  2013;23(6):654-663.
Atherosclerosis is a major risk factor for cardiovascular disease (CVD) and stroke. Galectin-3 is a carbohydrate-binding lectin implicated in the pathophysiology of CVD and is highly expressed within atherosclerotic lesions in mice and humans. The object of this present study was to use genetic deletion and pharmacological inhibition in a well-characterized mouse model of atherosclerosis to determine the role of galectin-3 in plaque development. Apolipoprotein-E/galectin-3 knockout mice were generated and fed a high-cholesterol “western” diet. Galectin-3 deletion had no consistent effect on the serum lipid profile but halved atherosclerotic lesion formation in the thoracic aorta (57% reduction), the aortic arch (50% reduction) and the brachiocephalic arteries. The aortic plaques were smaller, with reduced lipid core and less collagen. In apolipoprotein E-deficient (ApoE−/−) mice, there was a switch from high inducible nitric oxide expression in early lesions (6 weeks) to arginase-1 expression in later lesions (20 weeks), which was reversed in ApoE−/−/gal-3−/− mice. Administration of modified citrus pectin, an inhibitor of galectin-3, during the latter stage of the disease reduced plaque volume. We conclude that inhibiting galectin-3 causes decreased atherosclerosis. Strategies to inhibit galectin-3 function may reduce plaque progression and potentially represent a novel therapeutic strategy in the treatment of atherosclerotic disease.
PMCID: PMC3641797  PMID: 23426722
atherosclerosis; galectin-3; inflammation; macrophages; plaque
2.  Regulation of Transforming Growth Factor-β1–driven Lung Fibrosis by Galectin-3 
Rationale: Idiopathic pulmonary fibrosis (IPF) is a chronic dysregulated response to alveolar epithelial injury with differentiation of epithelial cells and fibroblasts into matrix-secreting myofibroblasts resulting in lung scaring. The prognosis is poor and there are no effective therapies or reliable biomarkers. Galectin-3 is a β-galactoside binding lectin that is highly expressed in fibrotic tissue of diverse etiologies.
Objectives: To examine the role of galectin-3 in pulmonary fibrosis.
Methods: We used genetic deletion and pharmacologic inhibition in well-characterized murine models of lung fibrosis. Further mechanistic studies were performed in vitro and on samples from patients with IPF.
Measurements and Main Results: Transforming growth factor (TGF)-β and bleomycin-induced lung fibrosis was dramatically reduced in mice deficient in galectin-3, manifest by reduced TGF-β1–induced EMT and myofibroblast activation and collagen production. Galectin-3 reduced phosphorylation and nuclear translocation of β-catenin but had no effect on Smad2/3 phosphorylation. A novel inhibitor of galectin-3, TD139, blocked TGF-β–induced β-catenin activation in vitro and in vivo and attenuated the late-stage progression of lung fibrosis after bleomycin. There was increased expression of galectin-3 in the bronchoalveolar lavage fluid and serum from patients with stable IPF compared with nonspecific interstitial pneumonitis and controls, which rose sharply during an acute exacerbation suggesting that galectin-3 may be a marker of active fibrosis in IPF and that strategies that block galectin-3 may be effective in treating acute fibrotic exacerbations of IPF.
Conclusions: This study identifies galectin-3 as an important regulator of lung fibrosis and provides a proof of principle for galectin-3 inhibition as a potential novel therapeutic strategy for IPF.
PMCID: PMC3410728  PMID: 22095546
fibrosis; epithelial cells; fibroblasts
3.  Loss of the Integrin-Activating Transmembrane Protein Fam38A (Piezo1) Promotes a Switch to a Reduced Integrin-Dependent Mode of Cell Migration 
PLoS ONE  2012;7(7):e40346.
Lung cancer is one of the most common fatal diseases in the developed world. The disease is rarely cured by currently available therapies, with an overall survival rate of ∼10%. Characterizing novel proteins that offer crucial insights into the processes of lung tumour invasion and metastasis may therefore provide much-needed prognostic markers, and influence therapeutic strategies. Aberrant function of the integrin family of heterodimeric cell surface receptors is a common theme in cancer - investigation into novel integrin activity regulators may offer crucial insights into the processes of tumour invasion and metastasis and may reveal insights into potential therapeutic targets. We previously described that depletion of the novel multi-transmembrane domain protein Fam38A, located at the endoplasmic reticulum (ER), inactivates endogenous beta1 integrin affinity, reducing cell adhesion. We now show that depletion of Fam38A, also now known as Piezo1, causes anchorage independence and a switch to a reduced integrin-dependent mode of cell migration/invasion, a novel phenotype for this integrin-regulating protein. Normal lung epithelial cells show increased rates of migration by 2D time-lapse microscopy and increased capacity to invade into matrigel, despite having decreased integrin affinity. We confirm greatly depleted Fam38A expression in small cell lung cancer (SCLC) lines where a form of reduced integrin-dependent migration, i.e. amoeboid migration, is a known phenotype. We propose that loss of Fam38A expression may cause increased cell migration and metastasis in lung tumours.
PMCID: PMC3390408  PMID: 22792288
4.  Critical role of c‐jun (NH2) terminal kinase in paracetamol‐ induced acute liver failure 
Gut  2006;56(7):982-990.
Acute hepatic failure secondary to paracetamol poisoning is associated with high mortality. C‐jun (NH2) terminal kinase (JNK) is a member of the mitogen‐activated protein kinase family and is a key intracellular signalling molecule involved in controlling the fate of cells.
To examine the role of JNK in paracetamol‐induced acute liver failure (ALF).
A previously developed mouse model of paracetamol poisoning was used to examine the role of JNK in paracetamol‐induced ALF.
Paracetamol‐induced hepatic JNK activation both in human and murine paracetamol hepatotoxicity and in our murine model preceded the onset of hepatocyte death. JNK inhibition in vivo (using two JNK inhibitors with different mechanisms of action) markedly reduced mortality in murine paracetamol hepatotoxicity, with a significant reduction in hepatic necrosis and apoptosis. In addition, delayed administration of the JNK inhibitor was more effective than N‐acetylcysteine after paracetamol poisoning in mice. JNK inhibition was not protective in acute carbon tetrachloride‐mediated or anti‐Fas antibody‐mediated hepatic injury, suggesting specificity for the role of JNK in paracetamol hepatotoxicity. Furthermore, disruption of the JNK1 or JNK2 genes did not protect against paracetamol‐induced hepatic damage. Pharmacological JNK inhibition had no effect on paracetamol metabolism, but markedly inhibited hepatic tumour necrosis foctor α (TNF α) production after paracetamol poisoning.
These data demonstrated a central role for JNK in the pathogenesis of paracetamol‐induced liver failure, thereby identifying JNK as an important therapeutic target in the treatment of paracetamol hepatotoxicity.
PMCID: PMC1994347  PMID: 17185352
5.  Cross-Linking CD98 Promotes Integrin-like Signaling and Anchorage-independent Growth 
Molecular Biology of the Cell  2002;13(8):2841-2852.
CD98, an early marker of T-cell activation, is an important regulator of integrin-mediated adhesion events. Previous studies suggest that CD98 is coupled to both cellular activation and transformation and is involved in the pathogenesis of viral infection, inflammatory disease, and cancer. Understanding of the molecular mechanisms underlying CD98 activity may have far-reaching practical applications in the development of novel therapeutic strategies in these disease states. Using small cell lung cancer cell lines, which are nonadherent, nonpolarized, and highly express CD98, we show that, in vitro, under physiological conditions, CD98 is constitutively associated with β1 integrins regardless of activation status. Cross-linking CD98 with the monoclonal antibody 4F2 stimulated phosphatidylinositol (PI) 3-kinase, PI(3,4,5)P3, and protein kinase B in the absence of integrin ligation or extracellular matrix engagement. Furthermore, cross-linking CD98 promoted anchorage-independent growth. Using fibroblasts derived from β1 integrin null stem cells (GD25), wild-type GD25β1, or GD25 cells expressing a mutation preventing β1 integrin-dependent FAK phosphorylation, we demonstrate that a functional β1 integrin is required for CD98 signaling. We propose that by cross-linking CD98, it acts as a “molecular facilitator” in the plasma membrane, clustering β1 integrins to form high-density complexes. This results in integrin activation, integrin-like signaling, and anchorage-independent growth. Activation of PI 3-kinase may, in part, explain cellular transformation seen on overexpressing CD98. These results may provide a paradigm for events involved in such diverse processes as inflammation and viral-induced cell fusion.
PMCID: PMC117946  PMID: 12181350
6.  The Small GTP-binding Protein R-Ras Can Influence Integrin Activation by Antagonizing a Ras/Raf-initiated Integrin Suppression Pathway 
Molecular Biology of the Cell  1999;10(6):1799-1809.
The rapid modulation of ligand-binding affinity (“activation”) is a central property of the integrin family of cell adhesion receptors. The small GTP-binding protein Ras and its downstream effector kinase Raf-1 suppress integrin activation. In this study we explored the relationship between Ras and the closely related small GTP-binding protein R-Ras in modulating the integrin affinity state. We found that R-Ras does not seem to be a direct activator of integrins in Chinese hamster ovary cells. However, we observed that GTP-bound R-Ras strongly antagonizes the Ras/Raf-initiated integrin suppression pathway. Furthermore, this reversal of the Ras/Raf suppressor pathway does not seem to be via a competition between Ras and R-Ras for common downstream effectors or via an inhibition of Ras/Raf-induced MAP kinase activation. Thus, R-Ras and Ras may act in concert to regulate integrin affinity via the activation of distinct downstream effectors.
PMCID: PMC25373  PMID: 10359597

Results 1-6 (6)