A -243A-->G polymorphism upstream of the gene encoding GAD65 associates with lower levels of body mass index and glycaemia in a population-based sample of 5857 middle-aged White subjects.

AIMS: The glutamate decarboxylase gene (GAD2) encodes GAD65, an enzyme catalysing the production of the gamma-aminobutyric acid (GABA) which interacts with neuropeptide Y to stimulate food intake. It has been suggested that in pancreatic islets, GABA serves as a functional regulator of pancreatic hormone release. Conflicting results have been reported concerning the potential impact of GAD2 variation on estimates of energy metabolism. The aim of this study was to elucidate potential associations between the GAD2-243A-->G polymorphism and levels of body mass index (BMI) and estimates of glycaemia. METHODS: Using high-throughput chip-based matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, the GAD2-243A-->G (rs2236418) polymorphism was genotyped in a population-based sample (Inter99) of 5857 middle-aged, unrelated Danish White subjects. RESULTS: The G-allele was associated with modestly lower BMI (P = 0.01). In a case-control study of obesity, the G-allele frequency in 2582 participants with BMI < 25 kg/m2 was 19.5% (18.4-20.6) compared with 17.1% (15.5-18.8) in 968 participants having BMI > or = 30 kg/m2 (P = 0.03), odds ratio 0.9 (0.7-1.0). Of the 5857 subjects, GG carriers had lower fasting plasma glucose levels (mmol/l) [AA (n = 3859) 5.6 +/- 0.8; AG (n = 1792) 5.5 +/- 0.8; GG (n = 206) 5.5 +/- 0.8, P = 0.008] and lower 30-min oral glucose tolerance test (OGTT)-related plasma glucose levels (AA 8.7 +/- 1.9; AG 8.6 +/- 1.9; GG 8.6 +/- 2.0, P = 0.04), adjusted for sex, age and BMI. Analysing subjects who were both normoglycaemic and glucose tolerant (n = 4431) GG carriers still had lower fasting plasma glucose concentrations: AA (n = 2895) 5.3 +/- 0.4; AG (n = 1383) 5.3 +/- 0.4; GG (n = 153) 5.2 +/- 0.4 (P = 9.10(-5)). CONCLUSION: The present study suggests that the GAD2-243A-->G polymorphism in a population of middle-aged White people associates with a modest reduction in BMI and fasting and OGTT-related plasma glucose levels.

Post-testicular sperm environment and fertility.

When mammalian spermatozoa exit the testis, they show a highly specialized morphology; however, they are not yet able to carry out their task: to fertilize an oocyte. This property, that includes the acquisition of motility and the ability to recognize and to fuse with the oocyte investments, is gained only after a transit through the epididymis during which the spermatozoa from the testis travel to the vas deferens. The exact molecular mechanisms that turn these cells into fertile gametes still remain mysterious, but surface-modifying events occurring in response to the external media are key steps in this process. Our laboratory has established cartographies of secreted (secretomes) and present proteins (proteomes) in the epididymal fluid of different mammals and have shown the regionalized variations in these fluid proteins along the epididymis. We have found that the main secreted proteins are common in different species and that enzymatic activities, capable of controlling the sperm surface changes, are present in the fluid. Our studies also indicate that the epididymal fluid is more complex than previously thought; it contains both soluble and particulate compartments such as exosome-like vesicles (epididymosomes) and certainly specific glycolipid-protein micelles. Understanding how these different compartments interplay to modify sperm components during their transit will be a necessary step if one wants to control and to ameliorate sperm quality and to obtain valuable fertility markers helpful to establish a male fertility based genetic selection.

Rat seminal vesicle FAD-dependent sulfhydryl oxidase. Biochemical characterization and molecular cloning of a member of the new sulfhydryl oxidase/quiescin Q6 gene family.

Rat FAD-dependent sulfhydryl oxidase was purified; partial sequencing indicated that it was homologous to human quiescin Q6. A cDNA (GenBank accession no. AF285078) was cloned from rat seminal vesicles, and active recombinant sulfhydryl oxidase was expressed in Chinese hamster ovary epithelial cells. This 2472-nucleotide cDNA has an open reading frame of 1710 base pairs, encoding a protein of 570 amino acids including a 32-amino acid leader sequence and two potential sites for N-glycosylation. One of them is used and the 64,000 M(r) purified protein was transformed to 61,000 by the action of endoglycosidase F. Northern blotting and reverse transcription-polymerase chain reaction analyses showed that there were small amounts of sulfhydryl oxidase in the rat testis, prostate, lung, heart, kidney, spleen, and liver, and that the gene was highly expressed in seminal vesicles and epididymis. Rat sulfhydryl oxidase cDNA corresponds to the human cell growth inhibiting factor cDNA, which could be a differently spliced form of quiescin Q6. Comparing sulfhydryl oxidase sequences with those of human quiescin Q6 and mammalian and Caenorhabditis elegans quiescin Q6-related genes established the existence of a new family of FAD-dependent sulfhydryl oxidase/quiescin Q6-related genes containing protein-disulfide isomerase-type thioredoxin and yeast ERV1 domains.