GAD2 on chromosome 10p12 is a candidate gene for human obesity

The gene GAD2 encoding the glutamic acid decarboxylase enzyme (GAD65) is a positional candidate gene for obesity on Chromosome 10p11–12, a susceptibility locus for morbid obesity in four independent ethnic populations. GAD65 catalyzes the formation of γ-aminobutyric acid (GABA), which interacts with neuropeptide Y in the paraventricular nucleus to contribute to stimulate food intake. A case-control study (575 morbidly obese and 646 control subjects) analyzing GAD2 variants identified both a protective haplotype, including the most frequent alleles of single nucleotide polymorphisms (SNPs) +61450 C>A and +83897 T>A (OR = 0.81, 95% CI [0.681–0.972], p = 0.0049) and an at-risk SNP (−243 A>G) for morbid obesity (OR = 1.3, 95% CI [1.053–1.585], p = 0.014). Furthermore, familial-based analyses confirmed the association with the obesity of SNP +61450 C>A and +83897 T>A haplotype (χ² = 7.637, p = 0.02). In the murine insulinoma cell line βTC3, the G at-risk allele of SNP −243 A>G increased six times GAD2 promoter activity (p < 0.0001) and induced a 6-fold higher affinity for nuclear extracts. The −243 A>G SNP was associated with higher hunger scores (p = 0.007) and disinhibition scores (p = 0.028), as assessed by the Stunkard Three-Factor Eating Questionnaire. As GAD2 is highly expressed in pancreatic β cells, we analyzed GAD65 antibody level as a marker of β-cell activity and of insulin secretion. In the control group, −243 A>G, +61450 C>A, and +83897 T>A SNPs were associated with lower GAD65 autoantibody levels (p values of 0.003, 0.047, and 0.006, respectively). SNP +83897 T>A was associated with lower fasting insulin and insulin secretion, as assessed by the HOMA-B% homeostasis model of β-cell function (p = 0.009 and 0.01, respectively). These data support the hypothesis of the orexigenic effect of GABA in humans and of a contribution of genes involved in GABA metabolism in the modulation of food intake and in the development of morbid obesity.     

Synthesis of 5-substituted-2,3-dihydro-1,4-benzoxathiins: biological evaluation as melatonin receptors ligands

The synthesis of benzoxathiins bearing a retroamide function is described from 8-hydroxythiochroman, the key step involving the synthesis of the benzoxathiin ring through a sulfonium salt. These new melatonin analogues were evaluated on human receptors MT1 and MT2 and have a similar affinity to that of melatonin itself.     

The expanding interleukin-1 family and its receptors: do alternative IL-1 receptor/signaling pathways exist in the brain?

Interleukin-1 (IL-1) has been implicated in neuroimmune responses and has pleiotropic actions in the brain. Compelling evidence has shown that IL-1 is a major mediator of inflammation and the progression of cell death in response to brain injury and cerebral ischemia. Its expression is strongly increased in these pathological conditions, and central administration of exogenous IL-1 significantly exacerbates ischemic brain damage. In contrast, inhibiting IL-1 actions (by intracerebroventricular [icv] injection of IL-1ra, neutralizing antibody to IL-1 or caspase-1 inhibitor) significantly reduces ischemic brain damage. IL-1 acts by binding to the IL-1 type-1 receptor (IL-1RI), which is to date, the only known functional receptor for IL-1. However, our recent investigations suggest that IL-1 can act independently of IL-1RI, raising the possibility that additional, as yet undiscovered, receptor(s) for IL-1 exist in the brain. The recent characterization of putative, new IL-1 ligands and new IL-1 receptor-related molecules leads to the hypothesis that there might be alternative IL-1 signaling pathway(s) in the central nervous system (CNS).     

Identification of the melatonin-binding site MT3 as the quinone reductase 2

The regulation of the circadian rhythm is relayed from the central nervous system to the periphery by melatonin, a hormone synthesized at night in the pineal gland. Besides two melatonin G-coupled receptors, mt(1) and MT(2), the existence of a novel putative melatonin receptor, MT(3), was hypothesized from the observation of a binding site in both central and peripheral hamster tissues with an original binding profile and a very rapid kinetics of ligand exchange compared with mt(1) and MT(2). In this report, we present the purification of MT(3) from Syrian hamster kidney and its identification as the hamster homologue of the human quinone reductase 2 (QR(2), EC ). Our purification strategy included the use of an affinity chromatography step which was crucial in purifying MT(3) to homogeneity. The protein was sequenced by tandem mass spectrometry and shown to align with 95% identity with human QR(2). After transfection of CHO-K1 cells with the human QR(2) gene, not only did the QR(2) enzymatic activity appear, but also the melatonin-binding sites with MT(3) characteristics, both being below the limit of detection in the native cells. We further confronted inhibition data from MT(3) binding and QR(2) enzymatic activity obtained from samples of Syrian hamster kidney or QR(2)-overexpressing Chinese hamster ovary cells, and observed an overall good correlation of the data. In summary, our results provide the identification of the melatonin-binding site MT(3) as the quinone reductase QR(2) and open perspectives as to the function of this enzyme, known so far mainly for its detoxifying properties.     

pH control of the plant outwardly-rectifying potassium channel SKOR

SKOR, an Arabidopsis depolarisation-activated K+-selective channel, was expressed in Xenopus oocytes, and external and internal pH effects were analysed. Internal pH was manipulated by injections of alkaline or acidic solutions or by acid load from acetate-containing medium. An internal pH decrease from 7.4 to 7.2 induced a strong (ca. 80%) voltage-independent decrease of the macroscopic SKOR current, the macroscopic gating parameters and the single channel conductance remained unchanged. An external acidification from 7.4 to 6.4 had similar effects. It is proposed that pH changes regulate the number of channels available for activation. Sensitivity of SKOR activity to pH in the physiological range suggests that internal and external pH play a role in the regulation of K+ secretion into the xylem sap.     

Regulation of Dlx gene expression in the zebrafish pharyngeal arches: from conserved enhancer sequences to conserved activity

The Dlx genes play an important role in the development of the pharyngeal arches and the structures derived from these tissues, including the craniofacial skeleton. They are typically expressed in a nested pattern along the proximo‐distal axis of the branchial arches in mice. This pattern is known as the “Dlx code” and has been proposed to be responsible for an early regional patterning of branchial arches in mammals. A number of cis‐ regulatory elements (CREs) have been identified within the Dlx loci, which target reporter expression to the developing pharyngeal arches of the mouse. Most of these CREs are located in the intergenic regions between the two genes constituting a Dlx bigene cluster. Therefore, the regionalized dlx expression in the branchial arches could be the result of the shared activities of these regulatory regions. Here we analyze previously published and new results showing these CREs are highly conserved in both their sequence and their activity in the pharyngeal arches of two distantly related vertebrates, the zebrafish and the mouse. A better understanding of Dlx gene regulation of the Dlx genes and of the genetic cascades in which they are involved can lead to clues explaining variations in morphology of the craniofacial regions of vertebrates.     

Two applications of 3D semi-landmark morphometrics implying different template designs: the theropod pelvis and the shrew skull

Geometric morphometrics involves defining landmark points to generate a discrete representation of an object. This crucial step is strongly influenced by the biological question guiding the analysis, and even more when using curve and surface semi-landmarks methods, because these require to generate a template of reference. We exemplify these constraints using two datasets from projects with very different backgrounds. The Theropod Dataset is a functional morphometric analysis of different extinct and extant theropod pelves. The Shrew Dataset is a populational morphometric analysis of the white-toothed shrew with very small variations in skull shape. We propose a novel procedure to generate a regular template configuration, using polygonal modelling tools. This method allows us to control the template geometry and adapt its complexity to the morphological variation in the sample. More studies are necessary to assess the morphometric and statistical importance of template design in curve and surface analyses.     

Une lame de faucille sous la stèle gravée Chalcolithique dite du « Chef de tribu », Vallée des Merveilles, région du Mont Bego, Tende, Alpes-Maritimes

The carved stele known as the “head of the tribe”, attributed to the Chalcolithic, erected at an altitude of 2290 m in the chaos of blocks in the Merveilles torrent in the Mont Bego region at Tende, was removed from its original standing place. Earth extracted from under the stele and sieved yielded a sickle blade in very fine and homogeneous Bedoulian pale biege translucid flint, pressure flaked on a heated core. The blade bears a light polish caused by cereal harvesting. This sickle blade is similar to those widely used in the southern Chassey culture (4300 to 3000 years before our era) but also sometimes in the Campaniform culture, during the ancient and middle Bronze age, like in Murée cave, in the Verdon gorges. The location of the sickle blade at the foot of the carved stele, known as the “head of the tribe”, is not just coincidental. It is highly probable that the blade was intentionally placed beside this rock. It is seemingly during a ritual ceremony that this sickle blade, probably still inserted in a wooden handle, was intentionally placed, in a propitious gesture or as an offering, beside the stele known as the “head of the tribe”.