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Ovarian cancer (OC) is the fifth most common cancer of female cancer death and leading cause of lethal gynecological cancers. High‐grade serous ovarian carcinoma (HGSOC) is an aggressive malignancy that is rapidly fatal. Many cases of OC show amplification of the 8q24 chromosomal region, which contains the well‐known oncogene MYC. Although MYC amplification is more frequently observed in OCs than in other tumor types, due to the large size of the 8q24 amplicon, the functions of the vast majority of the genes it contains are still unknown. The TIGD5 gene is located at 8q24.3 and encodes a nuclear protein with a DNA‐binding motif, but its precise role is obscure. We show here that TIGD5 often co‐amplifies with MYC in OCs, and that OC patients with high TIGD5 mRNA expression have a poor prognosis. However, we also found that TIGD5 overexpression in ovarian cancer cell lines unexpectedly suppressed their growth, adhesion, and invasion in vitro, and also reduced tumor growth in xenografted nude mice in vivo. Thus, our work suggests that TIGD5 may in fact operate as a tumor suppressor in OCs rather than as an oncogene. [ABSTRACT FROM AUTHOR]

Background: Perilipin A (PeriA) exclusively locates on adipocyte lipid droplets and is essential for lipid storage and lipolysis. Previously, we reported that adipocyte specific overexpression of PeriA caused resistance to diet-induced obesity and resulted in improved insulin sensitivity. In order to better understand the biological basis for this observed phenotype, we performed additional studies in this transgenic mouse model. Methodology and Principal Findings: When compared to control animals, whole body energy expenditure was increased in the transgenic mice. Subsequently, we performed DNA microarray analysis and real-time PCR on white adipose tissue. Consistent with the metabolic chamber data, we observed increased expression of genes associated with fatty acid β-oxidation and heat production, and a decrease in the genes associated with lipid synthesis. Gene expression of Pgc1a, a regulator of fatty acid oxidation and Ucp1, a brown adipocyte specific protein, was increased in the white adipose tissue of the transgenic mice. This observation was subsequently verified by both Western blotting and histological examination. Expression of RIP140, a regulator of white adipocyte differentiation, and the lipid droplet protein FSP27 was decreased in the transgenic mice. Importantly, FSP27 has been shown to control gene expression of these crucial metabolic regulators. Overexpression of PeriA in 3T3-L1 adipocytes also reduced FSP27 expression and diminished lipid droplet size. Conclusions: These findings demonstrate that overexpression of PeriA in white adipocytes reduces lipid droplet size by decreasing FSP27 expression and thereby inducing a brown adipose tissue-like phenotype. Our data suggest that modulation of lipid droplet proteins in white adipocytes is a potential therapeutic strategy for the treatment of obesity and its related disorders. [ABSTRACT FROM AUTHOR]

In higher plants the glutamate dehydrogenase (GDH) enzyme catalyzes the reversible amination of 2-oxoglutarate to form glutamate, using ammonium as a substrate. For a better understanding of the physiological function of GDH either in ammonium assimilation or in the supply of 2-oxoglutarate, we used transgenic tobacco (Nicotiana tabacum L.) plants overexpressing the two genes encoding the enzyme. An in vivo real time 15N-nuclear magnetic resonance (NMR) spectroscopy approach allowed the demonstration that, when the two GDH genes were overexpressed individually or simultaneously, the transgenic plant leaves did not synthesize glutamate in the presence of ammonium when glutamine synthetase (GS) was inhibited. In contrast we confirmed that the primary function of GDH is to deaminate Glu. When the two GDH unlabeled substrates ammonium and Glu were provided simultaneously with either [15N]Glu or 15NH4+ respectively, we found that the ammonium released from the deamination of Glu was reassimilated by the enzyme GS, suggesting the occurrence of a futile cycle recycling both ammonium and Glu. Taken together, these results strongly suggest that the GDH enzyme, in conjunction with NADH-GOGAT, contributes to the control of leaf Glu homeostasis, an amino acid that plays a central signaling and metabolic role at the interface of the carbon and nitrogen assimilatory pathways. Thus, in vivo NMR spectroscopy appears to be an attractive technique to follow the flux of metabolites in both normal and genetically modified plants. [ABSTRACT FROM PUBLISHER]

Abstract: Keratinocyte-specific Pten-null mice revealed distinct phenotypes, including epidermal and sebaceous gland hyperplasia. To determine the candidate genes that contribute to their phenotypes, we analyzed a comprehensive gene expression of Pten-null keratinocytes using microarray technology. Consequently, it was demonstrated that the most induced gene was adipocyte-specific fatty acid-binding protein (FABP4). Collectively, it is conceivable that the FABP4 pathway mediates the sebaceous gland hyperplasia in keratinocyte-specific Pten-null mice. [Copyright &y& Elsevier]

Our objective was to determine the respective roles of the couple glutamine synthetase/glutamate synthase (GS/GOGAT) and glutamate dehydrogenase (GDH) in ammonium and amino acid metabolism during germination and post-germinative growth in the model legume Medicago truncatula Gaertn. For this aim, amino acids were analyzed by HPLC and changes in gene expression of several enzymes involved in N and C metabolism were studied by real-time quantitative reverse transcription–polymerase chain reaction. Among the enzymes studied, GDH showed the highest increase in gene expression (80-fold), specifically in the embryo axis and concomitant with the increase in ammonium content during post-germinative growth. In cotyledons, GDH gene expression was very low. Although in vitro GDH aminating activity was several times higher than its deaminating activity, in vivo 15NH4 incorporation into amino acids was completely inhibited by methionine sulfoximine, a GS inhibitor, indicating that GDH is not involved in ammonium assimilation/detoxification. Changes in the expressions of GS and GOGAT isoforms revealed that GS1b (EC 6.3.1.2) in concert with NADH-dependent GOGAT (EC 1.4.1.14) constitute the major route of assimilation of ammonium derived from reserve mobilization and glutamic acid/glutamine synthesis in germinating M. truncatula seeds. However, during post-germinative growth, although germination was held in darkness, expression of GS2 and Fd-GOGAT (EC 1.4.7.1) increased and expression of GS1b decreased in cotyledons but not in the embryo axis. 2-Oxoglutarate, the substrate of the transamination reaction, was provided by the cytosolic isoform of isocitrate dehydrogenase (EC 1.1.1.42). We suggest that GDH during post-germinative growth, specifically in the developing embryo axis, contributes to ammonium delivery to GS for glutamine synthesis in the absence of primary NO3- assimilation. Interestingly, this reaction also produces reducing power (NADH) in organs deprived of photosynthesis. [ABSTRACT FROM AUTHOR]

Ferredoxin (Fd)-dependent glutamate synthase is present in green leaves, etiolated leaves, shoots, and roots of Arabidopsis thaliana (ecotype Columbia). In photosynthetic green leaves and shoots, Fd-dependent glutamate synthase accounts for more than 96% of the total glutamate synthase activity in vitro with the remaining activity derived from an enzyme that uses NADH as the electron donor. In etiolated leaves and roots, Fd-dependent glutamate synthase is 3-4-fold less active than in green leaves, but represents 70-85% of the total glutamate synthase activity in these tissues. Fd-dependent glutamate synthase is detected as a single peptide of 165 kDa on a western blot of green leaf and shoot tissues, and this Fd-dependent glutamate synthase polypeptide is 3-4-fold less abundant in etiolated leaves and roots. In these non-photosynthetic tissues, there is a higher activity of NADH-dependent glutamate synthase. The A. thaliana gltS mutant (strain CS254) contains, only 1.7% and 17.5% of the wild-type Fd-dependent glutamate synthase activity in leaves and roots, respectively. Western blots indicate that the Fd-dependent glutamate synthase peptide of 165 kDa is absent from leaves and roots of the gltS mutant. In contrast, NADH-dependent glutamate synthase activity in leaves and roots is unaffected. During illumination of wild-type dark-grown leaves for 72 h, the levels of Fd-dependent glutamate synthase protein and its activity increased threefold to levels equivalent to those in green leaves. In contrast, NADH-dependent glutamate synthase activity decreases, twofold during illumination. The complete nucleotide sequence of the complementary DNA for A. thaliana Fd-dependent glutamate synthase has been determined. Analysis of the amino acid sequence deduced from the complete cDNA sequence (5178 bp) has revealed that A. thaliana Fd-dependent glutamate synthase is synthesized as a 1648-amino-acid precursor protein (180090 Da) which consists of a 131-amino-acid transit peptide (14603 Da) and a 1517-amino-acid mature peptide (165487 Da). The A. thaliana Fd-dependent glutamate synthase has a high similarity to maize Fd-dependent glutamate synthase (83%) and to the analogous region of NADH-dependent glutamate synthase (42%) and NADPH-dependent glutamate synthases (40-43%) from different organisms. The A. thaliana Fd-dependent glutamate synthase contains the purF-type glutamine-amido-transfer domare as well as ravin and iron-sulfur-cluster-binding domains. The deduced primary structures of A. thaliana Fd-dependent glutamate synthase and of glutamate synthases from other organisms indicate that Fd-dependent glutamate synthase may have evolved from bacterial NADPH-dependent glutamate synthase. The cDNA hybridized to RNA of about 5.3 kb from different tissues of A. thaliana. A high steadystate level of Fd-dependent glutamate synthase mRNA is found in photosynthetic green leaves and shoots, and roots contain less mRNA for Fd-dependent glutamate synthase. In the gltS mutant, there are twofold and fourfold lower levels of Fd-dependent glutamate synthase mRNA in leaves and roots, respectively, relative to those in wild-type A. thaliana. Under continuous illumination of dark-grown leaves, the Fddependent glutamate synthase mRNA is induced twofold to a level equivalent to that in green leaves. [ABSTRACT FROM AUTHOR]

PTEN is a tumor suppressor gene mutated in many human cancers. We generated a bronchioalveolar epithelium-specific null mutation of Pten in mice [SP-C-rtTA/(tetO)(7)-Cre/Pten(flox/flox) (SOPten(flox/flox)) mice] that was under the control of doxycycline. Ninety percent of SOPten(flox/flox) mice that received doxycycline in utero [SOPten(flox/flox)(E10-16) mice] died of hypoxia soon after birth. Surviving SOPten(flox/flox)(E10-16) mice and mice that received doxycycline postnatally [SOPten(flox/flox)(P21-27) mice] developed spontaneous lung adenocarcinomas. Urethane treatment accelerated number and size of lung tumors developing in SOPten(flox/flox) mice of both ages. Histological and biochemical examinations of the lungs of SOPten(flox/flox)(E10-16) mice revealed hyperplasia of bronchioalveolar epithelial cells and myofibroblast precursors, enlarged alveolar epithelial cells, and impaired production of surfactant proteins. Numbers of bronchioalveolar stem cells (BASCs), putative initiators of lung adenocarcinomas, were increased. Lungs of SOPten(flox/flox)(E10-16) mice showed increased expression of Spry2, which inhibits the maturation of alveolar epithelial cells. Levels of Akt, c-Myc, Bcl-2, and Shh were also elevated in SOPten(flox/flox)(E10-16) and SOPten(flox/flox)(P21-27) lungs. Furthermore, K-ras was frequently mutated in adenocarcinomas observed in SOPten(flox/flox)(P21-27) lungs. These results indicate that Pten is essential for both normal lung morphogenesis and the prevention of lung carcinogenesis, possibly because this tumor suppressor is required for BASC homeostasis. [ABSTRACT FROM AUTHOR]