Regulation of netrin-1a expression by hedgehog proteins

Netrins, a family of growth cone guidance molecules, are expressed both in the ventral neural tube and in subsets of mesodermal cells. In an effort to better understand the regulation of netrins, we examined the expression of netrin-1a in mutant cyclops, no tail, and floating head zebrafish embryos, in which axial midline structures are perturbed. Netrin-1a expression requires signals present in notochord and floor plate cells. In the myotome, but not the neural tube, netrin-1a expression requires sonic hedgehog. In embryos lacking sonic hedgehog, the sonic-you locus, netrin-1a expression is reduced or absent in the myotomes but present in the neural tube. Embryos lacking sonic hedgehog express tiggy-winkle hedgehog in the floor plate, suggesting that, in the neural tube, tiggy-winkle hedgehog can compensate for the lack of sonic hedgehog in inducing netrin-1a expression. Ectopic expression of sonic hedgehog, tiggy-winkle hedgehog, or echidna hedgehog induces ectopic netrin-1a expression in the neural tube, and ectopic expression of sonic hedgehog or tiggy-winkle hedgehog, but not echidna hedgehog, induces ectopic netrin-1a expression in somites. These data demonstrate that in vertebrates netrin expression is regulated by Hedgehog signaling.     

Regulation of plasminogen gene expression by interleukin-6

Plasmin, the primary fibrinolytic enzyme, has a broad substrate spectrum and participates in other biological processes dependent upon proteolytic activity. Consequently, plasmin activity is tightly regulated by plasminogen activators and protease inhibitors. In this study, we examined whether regulation of plasminogen gene expression also might provide a new mechanism for controlling this system. We examined the effects of recombinant human interleukin-6 (rhIL-6), a pleiotropic cytokine, on plasminogen mRNA expression in primary murine hepatocytes and Hep3B human hepatoma cells. In primary hepatocytes, rhIL-6 and hydrocortisone separately increased plasminogen mRNA expression, but hydrocortisone did not markedly enhance the response to rhIL-6. Hep3B hepatoma cells exhibited more modest responses to rhIL-6. We used the polymerase chain reaction to amplify a 1,067-bp fragment of the human plasminogen promoter/5' flanking region. This fragment was cloned upstream of a luciferase reporter gene. Hep3B cells transiently transfected with this construct provided approximately 100-fold higher luciferase activity compared to cells transfected with control plasmids, and luciferase activity was increased approximately 4.5-fold when these cells were treated with rhIL-6. Furthermore, mice injected with rhIL-6 exhibited increases in hepatic plasminogen mRNA. Circulating plasminogen levels were significantly higher in the mice injected with rhIL-6 compared to mice injected with saline. Mice injected with lipopolysaccharide (an inducer of IL-6 in vivo) also showed increased hepatic plasminogen mRNA. Thus, plasminogen gene expression can be modulated by rhIL-6, suggesting a new mechanism for regulating biological systems that use plasmin.     

Regulation of IRF and STAT gene expression by retinoic acid

Ex vivo production of cytokines as determined by whole blood stimulation and supernatant ELISA is partly determined by heritability. To assess the ability of this system to distinguish between high and low producers the laboratory error and individual variation were investigated. Whole blood samples from healthy volunteers were collected using endotoxin-free tubes and were incubated with 0 to 1000 ng/ml lipopolysaccharide concentrations for 4 and 24 h, and subsequently centrifuged. In the supernatants, TNF-alpha and IL10 were measured by ELISA. Coefficients of variation for the day-to-day variation in the blood sampling, transport and stimulation as well as in the whole blood stimulation per se ranged from 7.5% to 12.3%. The intra-individual variation was 15% (TNF-alpha) and 19% (IL10) in contrast to the inter-individual variation of, on average, 35%. No interchanging of ranks between high and low producers was observed after repeating the whole blood stimulation on distinct days. The whole blood stimulation system is able to distinguish high and low producers of TNF-alpha and IL10.     

Regulation of tumor marker gene expression

Tumor marker is a group of proteins that specifically expressed in association with carcinogenic processes. Thus, studies of regulation mechanisms of the tumor marker genes are important for understanding the possible alteration of gene expression during neoplastic transformation. In this article, we described the molecular mechanisms of the regulation of two major tumor marker genes, i.e. human alpha-fetoprotein (AFP) gene and rat glutathione transferase P(GST-P) gene. Positive and negative mechanisms of each gene regulations are discussed.     

Regulation of chorionic gonadotropin gene expression

This paper describes the development of a high-performance liquid chromatographic method for the quantitation of free carnitine, total carnitine, acetylcarnitine, propionylcarnitine, isovalerylcarnitine, hexanoylcarnitine and octanoylcarnitine in human urine. Carnitine and acylcarnitines were isolated from 10 or 25 microliters of urine using 0.5-ml columns of silica gel, derivatized with 4'-bromophenacyl trifluoromethanesulfonate and separated by high-performance liquid chromatography. Using 4-(N,N-dimethyl-N-ethylammonio)-3-hydroxybutanoate ("e-carnitine") as the internal standard, standard curves (10-300 nmol/ml) were generated. Carnitine and acylcarnitines were quantified (when they were present) in normal human urine and the urine of patients diagnosed with one of three different disorders of organic acid metabolism: methylmalonic aciduria, isovaleric aciduria, isovaleric acidemia, and medium-chain acyl-CoA dehydrogenase deficiency.     

Regulation of expression of the erythropoietin gene

Vertebral hydatid cysts are rare and found in less than 1% of all the cases of hydatidosis. Neural compression is common in vertebral hydatidosis. The prognosis is generally regarded as very poor. This paper examines the natural history and complications which may arise during the treatment of vertebral hydatid cyst, and discusses their treatment. Thirteen cases of hydatid disease affecting the vertebrae are presented. The patients were admitted with symptoms of spinal cord compression. Twelve were treated by laminectomy and one by costotransversectomy. Low back pain radiating to the legs and lower extremity weakness were the predominant symptoms. Different degrees of pareses were present in 12 patients. Nine patients had impaired sensation in lower extremities. In 13 patients, 27 operations were performed. The major complication of surgery was the death of one patient due to the formaline irrigation. The surgical goal should be an extensive removal of the cysts and affected bone. The surgical area needs to be irrigated with hypertonic saline. Mebendazole or albendazole therapy seems to retard the recurrences and control the disease.     

Regulation of the expression of the tissue transglutaminase gene by DNA methylation

We have investigated the role of DNA methylation in the regulation of the expression of the human tissue transglutaminase gene. Studies on the methylation of the transglutaminase promoter in normal and neoplastic human cells demonstrated that the promoter is methylated in vivo and hypomethylation of the promoter is correlated with constitutive gene expression. Demethylation of the promoter in vivo by treatment of the cells with 5-azacytidine increased transglutaminase expression and hypermethylation of the promoter in vitro suppressed its activity. These studies suggest that alternations in DNA methylation may be one of the mechanisms regulating the tissue-specific expression of the tissue transglutaminase gene.     

Regulation of gene expression in developing epidermal epithelia

Studies of conditioned locomotor activity typically use an entire environmental context as the conditioned stimulus. To determine whether conditioned locomotion can be elicited by specific, discrete stimuli similar to those used in traditional studies of classical conditioning, rats were injected intraperitoneally (i.p.) with saline before 30 min sessions in a locomotor activity chamber. Interspersed (one to two times a week) with these baseline sessions, the rats were injected with cocaine (20 mg/kg) and placed in the chamber with a tone or flashing light present. Although baseline levels of activity remained stable, locomotion increased (sensitized) over six drug-stimulus pairings. Conditioned locomotor activity was elicited when the stimuli were then presented in the absence of cocaine. When a cocaine challenge was administered, locomotor activity was higher in the presence of the conditioned stimuli than in their absence, indicating that conditioning contributed to sensitization. These conditioned effects did not occur in control groups in which cocaine was not associated with the stimulus. To determine whether reinforcing properties had been conditioned to the stimuli, the rats were then tested in an operant chamber where responding in one nose-poke hole produced a 2 s conditioned-stimulus presentation. Rats that had received stimulus-drug pairings responded at a higher rate in this hole than in another, inactive hole. Locomotor activity can thus be conditioned to discrete stimuli, and the reinforcing properties conditioned to these stimuli can transfer to other environments. In this respect, the drug-conditioning effects seen in rodents appear to be analogous to the conditioned responses observed when human drug abusers are presented with discrete, drug-related stimuli.