Apoptotic cell death plays an important role in limiting testicular germ cell population during spermatogenesis and its dysregulation has been shown to be associated with male infertility. The growing evidence on the role of the transcription factor nuclear factor (NF)-kappa B in controlling apoptosis prompted us to investigate NF-kappa B activity in the normal human testis and its role in testis tissue undergoing excessive apoptosis in vitro. In electrophoretic mobility shift assays, low-level constitutive NF-kappa B DNA-binding activity was found and, by immunostaining of the RelA and p50 NF-kappa B subunits, was localized to Sertoli cell nuclei. During in vitro-induced testicular apoptosis, the Sertoli cell nuclear NF-kappa B levels and whole seminiferous tubule NF-kappa B DNA-binding activity increased previous detection of germ cells undergoing apoptosis. The anti-inflammatory drug sulfasalazine effectively suppressed stress-induced NF-kappa B DNA binding and NF-kappa B-mediated I kappa B alpha gene expression. Importantly, concomitantly with inhibiting NF-kappa B, sulfasalazine blocked germ cell apoptosis. These results suggest that during testicular stress Sertoli cell NF-kappa B proteins exert proapoptotic effects on germ cells, which raises the possibility that pharmacological inhibition of NF-kappa B could be a therapeutic target in transient stress situations involving excessive germ cell death.

Renal XOR induction in SHRs does not precede the development of hypertension, but progress concomitantly with an increase in SBP. The results indicate a role for locally synthesized XOR in the development of hypertension-associated end-organ damage, but no major role in the development of hypertension.

BACKGROUND: Linkage and knock-out mice studies suggest that the melanocortin-3-receptor (MC3R) is a candidate gene for obesity. OBJECTIVE: To evaluate whether MC3R mutations underlie morbid obesity. SUBJECTS AND METHODS: MC3R coding and 5 0 -flanking regions were sequenced in 48 subjects and the detected variants genotyped in 252 morbidly obese (BMI ! 40 kg/m 2 ) Finns. Gel shifts were used to examine whether a mutation in the putative promoter alters GATA-factor binding. RESULTS: Three common MC3R variants were found: a 17C > A variant, changing Thr6?Lys in 16%, a 241G > A variant changing Val81?Ile in 15%, and a 7239A > G substitution in the GATA binding site in 21% of the subjects. Four other variants were detected in the 5 0 flanking region. Frequencies of the three common variants did not differ between obese and contol subjects. Among the obese, the 17C > A and 241G > A variants were coinherited and associated with increased insulin -glucose ratios (P < 0.05) and leptin levels (P < 0.05). GATA-4 bound efficiently to wild type oligonucleotide, but only weakly to the oligonucleotide with the 7239A > G mutation. CONCLUSIONS: MC3R gene variants are common and do not explain human morbid obesity. These variants associated with subtle changes in onset of weight gain, hyperleptinemia and insulin -glucose ratios. The 7239A > G mutation abolishes binding of GATA-4 to the MC3R promoter region.

No abstract

O. Raivio. Posttranslational inactivation of human xanthine oxidoreductase by oxygen under standard cell culture conditions. Am J Physiol Cell Physiol 285: C48-C55, 2003. First published March 12, 2003 10.1152/ajpcell.00561.2002 catalyzes the final reactions of purine catabolism and may account for cell damage by producing reactive oxygen metabolites in cells reoxygenated after hypoxia. We found a three-to eightfold higher XOR activity in cultured human bronchial epithelial cells exposed to hypoxia (0.5-3% O 2) compared with cells grown in normoxia (21% O 2) but no difference in XOR protein or mRNA. XOR promoter constructs failed to respond to hypoxia. The cellular XOR activity at 3% O 2 returned to basal levels when the cells were returned to 21% O 2, and hyperoxia (95% O2) abolished enzyme activity with no change in XOR protein.Our data suggest reversible enzyme inactivation by oxygen or its metabolites. NADH was normally oxidized by the oxygen-inactivated enzyme, which rules out damage to the flavin adenine dinucleotide cofactor. Hydrogen peroxide partially inactivated the molybdenum center of XOR, as shown by a parallel decrease in XOR-catalyzed xanthine oxidation and dichlorophenolindophenol reduction. We conclude that the transcription or translation of XOR is not influenced by hypoxia or hyperoxia. Instead, the molybdenum center of XOR is posttranslationally inactivated by oxygen metabolites in "normal" (21% O 2) cell culture atmosphere. This inactivation is reversed in hypoxia and accounts for the apparent induction. xanthine oxidase; hypoxia; hyperoxia; ischemia reperfusion