Mimp/Mtch2, an Obesity Susceptibility Gene, Induces Alteration of Fatty Acid Metabolism in Transgenic Mice.

Metabolic dysfunctions, such as fatty liver, obesity and insulin resistance, are among the most common contemporary diseases worldwide, and their prevalence is continuously rising. Mimp/Mtch2 is a mitochondrial carrier protein homologue, which localizes to the mitochondria and induces mitochondrial depolarization. Mimp/Mtch2 single-nucleotide polymorphism is associated with obesity in humans and its loss in mice muscle protects from obesity. Our aim was to study the effects of Mimp/Mtch2 overexpression in vivo.Transgenic mice overexpressing Mimp/Mtch2-GFP were characterized and monitored for lipid accumulation, weight and blood glucose levels. Transgenic mice liver and kidneys were used for gene expression analysis.Mimp/Mtch2-GFP transgenic mice express high levels of fatty acid synthase and of β-oxidation genes and develop fatty livers and kidneys. Moreover, high-fat diet-fed Mimp/Mtch2 mice exhibit high blood glucose levels. Our results also show that Mimp/Mtch2 is involved in lipid accumulation and uptake in cells and perhaps in human obesity.Mimp/Mtch2 alters lipid metabolism and may play a role in the onset of obesity and development of insulin resistance

HGF/SF Increases Tumor Blood Volume: A Novel Tool for the In Vivo Functional Molecular Imaging of Met

Molecular functional and metabolic imaging allows visualization of disease-causing processes in living organisms. Here we present a new approach for the functional molecular imaging (FMI) of endogenous tyrosine kinase receptor activity using Met and its ligand, hepatocyte growth factor/scatter factor (HGF/SF), as a model. HGF/SF and Met play significant roles in the biology and pathogenesis of a wide variety of cancers and, therefore, may serve as potential targets for cancer prognosis and therapy. We have previously shown that Met activation by HGF/SF increases oxygen consumption in vitro and results in substantial alteration of blood oxygenation levels in vivo, as measured by blood oxygenation level-dependent magnetic resonance imaging. Using contrast medium (CM) ultrasound imaging, we demonstrate here that HGF/SF induces an increase in tumor blood volume. This increase is evident in small vessels, including vessels that were not detected before HGF/SF treatment. The specificity of the effect was validated by its inhibition using anti-HGF/SF antibodies. This change in tumor hemodynamics, induced by HGF/SF and measured by CM ultrasound, is further used as a tool for Met FMI in tumors. This novel noninvasive molecular imaging technique may be applied for the in vivo diagnosis, prognosis, and therapy of Met-expressing tumors

Detection of fatty livers and kidneys and blood glucose levels in Mimp/Mtch2-GFP transgenic mice.

<p><b>A.</b> (a) Ultrasound analysis of control (I) and Mimp/Mtch2-GFP transgenic mouse (II), 14 month old. (b) Calculation of % of mice showing fatty changes in H&E stained fixed sections from Mimp/Mtch2-GFP (n = 18) and WT (n = 7) mice. <i>P</i> = 0.0003 for both liver and kidney (Chi test). All mice were maintained on HFD. <b>B.</b> (a) H&E staining of fixed sections. (I) Control mouse liver. (II) Liver section of Mimp/Mtch2-GFP transgenic mouse. Fat vesicles are indicated by arrow. (III) Control mouse showing a normal kidney. (IV) Kidney section obtained from a Mimp/Mtch2-GFP transgenic mouse shows fatty vesicles that accumulate mainly in the proximal convoluted tubules of the kidney (indicated by arrow). Bars represent 0.10 mm. (b) Oil-Red-O staining of Mimp/Mtch2-GFP transgenic mouse showing fatty liver (II) and fatty kidney (IV), and of control mouse showing normal liver (I) and kidney (III). All mice were between the ages of 12 and 14 month and maintained on HFD from birth. <b>C.</b> Glucose levels and weight in Mimp/Mtch2-GFP mice. Mimp/Mtch2-GFP transgenic mice (n = 16) and age matched control mice (n = 12) consuming high or low fat diets were monitored weekly in the mornings for their (a) blood glucose levels and (b) their weight. Measurements were performed between the ages of 9 to 16 month and then averaged for all time points and all mice. All bar graphs results are expressed as means ± SEM. Groups were compared using ANOVA with Tukey’s post hoc.</p

Mimp/Mtch2 increases expression of lipids, lipid uptake and lipid metabolism genes in HEK-293T cells.

<p><b>A.</b> Oil-red-O staining of HEK-293T cells transiently expressing Mimp/Mtch2-GFP (b) and control non-transfected cells (a). <b>B.</b> HEK-293T cells were transfected with Mimp/Mtch2-GFP or an empty GFP vector. RNA was extracted and measured by qRT-PCR for the expression of MCAD, Thiolase and FASN. Expression between the groups was compared using Student’s t-test. <b>C.</b> HEK-293T cells were transfected with Mimp/Mtch2-GFP or an empty GFP vector. Cells medium was supplemented with 100 or 200 μM oleic acid for 24 hours and cells were stained for triglycerides using oil-red-O. Cells were imaged using Leica and oil-red-O signal intensity was quantified using Image J software. Each bar represents an average of at least 6 fields and experiment was repeated 3 times. Groups were compared using ANOVA with Tukey’s post hoc. All bar graphs results are expressed as means ± SEM.</p

Gene expression in obesity.

<p>The expression levels of: <b>A.</b> Mimp/Mtch2 and <b>B.</b> MCAD and Thiolase, in pre-published cDNA microarray from human skeletal muscle of non-obese, obese and morbidly obese patients [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0157850#pone.0157850.ref019" target="_blank">19</a>]. All bar graphs results are expressed as means ± SEM. The non-obese and morbidly obese groups were compared using Student’s t-test.</p

Cluster analysis of cDNA microarray and gene expression in Mimp/Mtch2-GFP mice.

<p><b>A.</b> K-Means clustering over 57 probes that change significantly (p<0.05) in fatty (n = 2) compared to non-fatty (n = 2) kidneys of Mimp/Mtch2-GFP transgenic mice consuming HFD. Rows, genes; Columns, samples. Down-regulation is colored in green and up-regulation is colored in red. <b>B.</b> Quantitative real time PCR (qRT-PCR) for gene expression of (a) Mimp/Mtch2, (b) MCAD and Thiolase and (c) FASN, in livers (I) and kidneys (II) of control (WT) and Mimp/Mtch2-GFP transgenic mice, in the ages of 21–23 month, consuming low fat diet. The transgenic mice were divided into 2 groups of low and high Mimp/Mtch2 according to Mimp/Mtch2 expression levels. Each group consists of at least 3 mice. Results are represented as averaged relative quantity (RQ) of the mice in each group. All bar graphs results are expressed as means ± SEM. Groups were compared using ANOVA with Tukey’s post hoc.</p

In Vivo Direct Molecular Imaging of Early Tumorigenesis and Malignant Progression Induced by Transgenic Expression of GFP-Met

The tyrosine kinase receptor Met and its ligand, hepatocyte growth factor/scatter factor (HGF/SF), play an important role in normal developmental processes, as well as in tumorigenicity and metastasis. We constructed a green fluorescent protein (GFP) Met chimeric molecule that functions similarly to the wild-type Met receptor and generated GFP-Met transgenic mice. These mice ubiquitously expressed GFP-Met in specific epithelial and endothelial cells and displayed enhanced GFP-Met fluorescence in sebaceous glands. Thirty-two percent of males spontaneously developed adenomas, adenocarcinomas, and angiosarcomas in their lower abdominal sebaceous glands. Approximately 70% of adenocarcinoma tumors metastasized to the kidneys, lungs, or liver. Quantitative subcellular-resolution intravital imaging revealed very high levels of GFP-Met in tumor lesions and in single isolated cells surrounding them, relative to normal sebaceous glands. These single cells preceded the formation of local and distal metastases. Higher GFP-Met levels correlated with earlier tumor onset and aggressiveness, further demonstrating the role of Met-HGF/SF signaling in cellular transformation and acquisition of invasive and metastatic phenotypes. Our novel mouse model and high-resolution intravital molecular imaging create a powerful tool that enables direct real-time molecular imaging of receptor expression and localization during primary events of tumorigenicity and metastasis at single-cell resolution

Epigenetic loss of m1A RNA demethylase ALKBH3 in Hodgkin lymphoma targets collagen conferring poor clinical outcome

We thank CERCA Programme/Generalitat de Catalunya for institutional support. This work was supported by the Health Department PERIS-project no. SLT/002/16/00374 and AGAUR-projects no. 2017SGR1080 of the Catalan Government (Generalitat de Catalunya); Ministerio de Ciencia e Innovación (MCI), Agencia Estatal de Investigación (AEI) and European Regional Development Fund (ERDF) project no. RTI2018-094049-B-I00; the Cellex Foundation; and “la Caixa” Banking Foundation (LCF/PR/GN18/51140001). P.S.O. is a fellow of the Severo Ochoa Program (Bp17- 165). V.D. is supported by the Spanish Association Against Cancer (AECC).Peer reviewe