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Nutrient-driven O -GlcNAcylation has been linked to epigenetic regulation of gene expression in metazoans. In C. elegans, O -GlcNAc marks the promoters of over 800 developmental, metabolic, and stress-related genes; these O -GlcNAc marked genes show a strong 5′, promoter-proximal bias in the distribution of RNA Polymerase II (Pol II). In response to starvation or feeding, the steady state distribution of O -GlcNAc at promoters remain nearly constant presumably due to dynamic cycling mediated by the transferase OGT-1 and the O -GlcNAcase OGA-1. However, in viable mutants lacking either of these enzymes of O -GlcNAc metabolism, the nutrient-responsive GlcNAcylation of promoters is dramatically altered. Blocked O -GlcNAc cycling leads to a striking nutrient-dependent accumulation of O -GlcNAc on RNA Pol II. O -GlcNAc cycling mutants also show an exaggerated, nutrient-responsive redistribution of promoter-proximal RNA Pol II isoforms and extensive transcriptional deregulation. Our findings suggest a complex interplay between the O -GlcNAc modification at promoters, the kinase-dependent “CTD-code,” and co-factors regulating RNA Pol II dynamics. Nutrient-responsive O -GlcNAc cycling may buffer the transcriptional apparatus from dramatic swings in nutrient availability by modulating promoter activity to meet metabolic and developmental needs. [ABSTRACT FROM AUTHOR]

Discriminating pathogenic bacteria from bacteria used as a food source is key to Caenorhabidits elegans immunity. Using mutants defective in the enzymes of O-linked N-acetylglucosamine (O-GlcNAc) cycling, we examined the role of this nutrient-sensing pathway in the C. elegans innate immune response. Genetic analysis showed that deletion of O-GlcNAc transferase (ogt-1) yielded animals hypersensitive to the human pathogen S. aureus but not to P. aeruginosa. Genetic interaction studies revealed that nutrient-responsive OGT-1 acts through the conserved β-catenin (BAR-1) pathway and in concert with p38 MAPK (PMK-1) to modulate the immune response to S. aureus. Moreover, whole genome transcriptional profiling revealed that O-GlcNAc cycling mutants exhibited deregulation of unique stress- and immune-responsive genes. The participation of nutrient sensor OGT-1 in an immunity module evolutionarily conserved from C. elegans to humans reveals an unexplored nexus between nutrient availability and a pathogen-specific immune response. [ABSTRACT FROM AUTHOR]

The carbohydrate modification of serine and threonine residues with O-linked beta- N-acetylglucosamine (O-GlcNAc) is ubiquitous and governs cellular processes ranging from cell signaling to apoptosis.The O-GlcNAc modification along with other carbohydrate modifications, including N-linked and O-linked glycans, glycolipids, and sugar polymers, all require the use of the nucleotide sugar UDP-GlcNAc, the end product of the hexosamine biosynthetic pathway (HBP). In this paper, we describe the biochemical consequences resulting from perturbation of the O-GlcNAc pathway in C. elegans lacking O-GlcNAc transferase and O-GlcNAcase activities. In ogt-1 null animals, steady-state levels of UDPGlcNAc/ UDP-GalNAc and UDP-glucose were substantially elevated. Transcripts of genes encoding for key members in the HBP (gfat-2, gna-2, C36A4.4) and trehalose metabolism (tre-1, tre-2, tps-2) were elevated in ogt-1 null animals. While there is no evidence to suggest changes in the profile of N-linked glycans in the ogt-1 and oga-1 mutants, glycans insensitive to PNGase digestion (including O-linked glycans, glycolipids, and glycopolymers) were altered in these strains. Our data support that changes in O-GlcNAcylation alters nucleotide sugar production, overall glycan composition, and transcription of genes encoding glycan processing enzymes. These data along with our previous findings that disruption in O-GlcNAc cycling alters macronutrient storage underscores the noteworthy influence this posttranslational modification plays in nutrient sensing. [ABSTRACT FROM AUTHOR]

Thiols provide the major intracellular redox milieu and can undergo reversible oxidation and reduction. To understand the role of thiols in redox signaling events, we have studied the effect of N-ethylmaleimide, a specific thiol alkylating agent, on platelet-derived growth factor-BB (PDGF-BB)-induced mitogenesis in vascular smooth muscle cells (VSMC). Thiol alkylation inhibited PDGF-BB-induced expression of the Fos and Jun family proteins and AP-1 activity in VSMC. Thiol alkylation also inhibited PDGF-BB-induced expression of cyclin A and growth in these cells. In contrast, thiol alkylation enhanced and sustained the effect of PDGF-BB on the activation of the Jak STAT pathway, and this event was correlated with inhibition of protein tyrosine phosphatase lB activity. Thiol alkylation via inducing the expression of p21waf1/cip1 in a STAT1- and p53-dependent manner antagonized the downregulation of this cell cycle inhibitory molecule by PDGF-BB. The inhibition of AP-1 and activation of STATs, particularly STAT1, by thiol alkylation correlated with increased production of active caspase 1 and apoptosis in VSMC. Together, these findings suggest a role for thiols in mediating mitogenic and/or apoptotic signaling events in VSMC. These results also show that a sustained change in the intracellular thiol redox state can convert a mitogen into a death promoter.Oncogene (2003) 22, 117–130. doi:10.1038/sj.onc.1206065 [ABSTRACT FROM AUTHOR]

Presents several medical case studies. Association of water intoxication with carbamazepine treatment; Diagnosis of Miliary Crohn's disease; Effect of glibenclamide on antidiuretic hormones.

A three-year-old boy with positive diagnostic criteria for both Toxocara infection and active Toxoplasma infection was referred to the Pediatric Outpatient Department in Great Britain. He had a history of irregular fever, malaise, lethargy, occasional headache, and vomiting for two months. He was the fourth child in a family of five, of Indian parents, born in Wolverhampton, England following an uneventful full-term pregnancy and normal delivery. The medical history of the family was noncontributory. Treatment with diethylcarbamazine maintained for two weeks produced no appreciable improvement. A four weeks' course of pyrimethamine and sulphadiazine was then started, along with folic acid, iron, and vitamin supplements produced better results.

In a variety of organisms, including worms, flies, and mammals, glucose homeostasis is maintained by insulin-like signaling in a robust network of opposing and complementary signaling pathways. The hexosamine signaling pathway, terminating in O-linked-N-acetylglucosamine (O-1cNAc) cycling, is a key sensor of nutrient status and has been genetically linked to the regulation of insulin signaling in Caenorhabditis elegans. Here we demonstrate that O-G1cNAc cycling and insulin signaling are both essential components of the C. elegans response to glucose stress. A number of insulin-dependent processes were found to be sensitive to glucose stress, including fertility, reproductive timing, and dauer formation, yet each of these differed in their threshold of sensitivity to glucose excess. Our findings suggest that O-G1cNAc cycling and insulin signaling are both required for a robust and adaptable response to glucose stress, but these two pathways show complex and interdependent roles in the maintenance of glucose-insulin homeostasis. [ABSTRACT FROM AUTHOR]

Thiols provide the major intracellular redox milieu and can undergo reversible oxidation and reduction. To understand the role of thiols in redox signaling events, we have studied the effect of N-ethylmaleimide, a specific thiol alkylating agent, on platelet-derived growth factor-BB (PDGF-BB)-induced mitogenesis in vascular smooth muscle cells (VSMC). Thiol alkylation inhibited PDGF-BB-induced expression of the Fos and Jun family proteins and AP-1 activity in VSMC. Thiol alkylation also inhibited PDGF-BB-induced expression of cyclin A and growth in these cells. In contrast, thiol alkylation enhanced and sustained the effect of PDGF-BB on the activation of the Jak STAT pathway, and this event was correlated with inhibition of protein tyrosine phosphatase lB activity. Thiol alkylation via inducing the expression of p21waf1/cip1 in a STAT1- and p53-dependent manner antagonized the downregulation of this cell cycle inhibitory molecule by PDGF-BB. The inhibition of AP-1 and activation of STATs, particularly STAT1, by thiol alkylation correlated with increased production of active caspase 1 and apoptosis in VSMC. Together, these findings suggest a role for thiols in mediating mitogenic and/or apoptotic signaling events in VSMC. These results also show that a sustained change in the intracellular thiol redox state can convert a mitogen into a death promoter.Oncogene (2003) 22, 117–130. doi:10.1038/sj.onc.1206065 [ABSTRACT FROM AUTHOR]