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Y Z Ye

Publications and source records attributed to Y Z Ye.

15 recordsLinked to original sources
PubMed2006

Thermal nociception in adult Drosophila: behavioral characterization and the role of the painless gene.

Nociception, warning of injury that should be avoided, serves an important protective function in animals. In this study, we show that adult Drosophila avoids noxious heat by a jump response. To quantitatively analyze this nociceptive behavior, we developed two assays. In the CO2 laser beam assay, flies exhibit this behavior when a laser beam heats their abdomens. The consistency of the jump latency in this assay meets an important criterion for a good nociceptive assay. In the hot plate assay, flies jump quickly to escape from a hot copper plate (>45 degrees C). Our results demonstrate that, as in mammals, the latency of the jump response is inversely related to stimulus intensity, and innoxious thermosensation does not elicit this nociceptive behavior. To explore the genetic mechanisms of nociception, we examined several mutants in both assays. Abnormal nociceptive behavior of a mutant, painless, indicates that painless, a gene essential for nociception in Drosophila larvae, is also required for thermal nociception in adult flies. painless is expressed in certain neurons of the peripheral nervous system and thoracic ganglia, as well as in the definite brain structures, the mushroom bodies. However, chemical or genetic insults to the mushroom bodies do not influence the nociceptive behavior, suggesting that different painless-expressing neurons play diverse roles in thermal nociception. Additionally, no-bridge(KS49), a mutant that has a structural defect in the protocerebral bridge, shows defective response to noxious heat. Thus, our results validate adult Drosophila as a useful model to study the genetic mechanisms of thermal nociception.

Animals↗
PubMed2001

The Inhibitory Activities of Recombinant Eglin C Mutants on Kexin and Furin, Using Site-directed Mutagenesis and Molecular Modeling.

Mammalian furin and yeast kexin are members of the proprotein convertase family involved in the proteolytic processing of many important precursor proteins. Here the gene coding for the subtilisin inhibitor eglin C was totally synthesized and expressed in E.coli. Substitution of residues at each position P(1), P(2) and P(4) of eglin C with a basic residue using protein engineering could make eglin C a very strong inhibitor for furin (K(i) around 10(-9) mol/L),and even more strong for kexin (K( i ) around 10(-11) mol/ L). Results indicated that (1) A basic residue Lys or Arg at P(1) site is prerequisite for the inhibitor. (2) The second mutation with basic residue at P(4) site drastically increase the inhibitory activity by two orders of magnitude. (3) A basic residue at P(2) site is favorable for the binding to the enzyme, but unfavorable for the stability of the inhibitor, resulting in a temporary inhibition. (4) A hydrophobic residue is preferential at P(3) site. Based on the known crystal structures of subtilisin and eglin C, the interaction between the enzyme and inhibitor was modeled, and their involved residues were predicted which gave a good explanation to the experimental results.

Journal Article↗
PubMed2000

Effects of ICAM-1 antisense oligonucleotide on the tubulointerstitium in mice with unilateral ureteral obstruction.

UNLABELLED: Effects of ICAM-1 antisense oligonucleotide on the renal tubulointerstitium in mice with unilateral ureteral obstruction. BACKGROUND: To extend our previous study of the therapy of the renal lesions of unilateral ureteral obstruction (UUO) in mice by an inhibitor of intercellular adhesion molecule-1 (ICAM-1), we investigated the blocking effects of ICAM-1 antisense oligonucleotides (ASONs) on the ICAM-1 expression in mouse kidney. METHODS: First, ICAM-1 ASON was transducted into mouse renal tubular epithelial cells to investigate the effects of ICAM-1 ASON in vitro. Second, fluorescein isothiocyanate (FITC)-labeled ICAM-1 ASON was injected intravenously to determine the distribution of the ASON in vivo. Third, the expression of ICAM-1 in kidney and the changes of renal morphology were observed to investigate the therapeutic effects of ICAM-1 ASON on the UUO mice in vivo. RESULTS: The expressions of ICAM-1 in the epithelial cells induced by interleukin-1beta were inhibited by ICAM-1 ASON at the dosages of 100 and 200 nmol/L. Twenty-four hours after an introvenous injection with FITC-labeled ICAM-1 ASON, the highest level of fluorescein was detected within the proximal tubules in mouse kidney. Results of immunohistology and Northern blot showed that the ICAM-1 expression was markedly reduced in the obstructed kidney after treatment with ICAM-1 ASON. The ASON also alleviated the infiltration of inflammatory cells and accumulation of the extracellular matrix in the tubulointerstitium of UUO mice without apparent side effects. CONCLUSION: Our data demonstrate that ICAM-1 ASON is taken up primarily by the proximal tubular cells of mouse kidney. ICAM-1 ASON can selectively inhibit the ICAM-1 expression of the renal tubular cells both in vitro and in vivo.

Animals↗
PubMed2000

[The expression patterns of genes in different biotypes by genome addition].

The patterns of SOD, EST and haemoglobin genes expression among the different combinations conducted with genome addition were investigated. The erythrocyte expression of these isozymes and protein were visualized by histochemical staining after polyacrylamide gradient gel electrophoresis. The results of our electrophoresis analysis have revealed that biochemical polymorphism exists in the combinations, and these genetic variance have resulted from the contribution of different genomes. This study provides additional evidence that gene dosages can be interpreted from the enzyme patterns and electrophoretic staining intensities existed in different ploidies, which suggests that subunit interactions for SOD are co-operative and additive. This would indicate that each allele could be differentially regulated so that even one-third genome can be expressed in triploid individuals. These genetic data could be used to construct genome specific varieties, and would not only help to maximize efficiency in the use of different biotypes identification, but also help to maximize studying the relationship between gene dosage, expression and regulation.

Animals↗
PubMed2000

[Expression of citrate transporter mRNA in the kidneys of rats with metabolic acidosis].

The purpose of the present study was to examine whether metabolic acidosis affects the expression of rat renal Na(+)/citrate cotransporter. Female Wistar rats were pair-fed with normal rat chow and drinking water (control) or water with 0.28 mol/L NH4Cl (metabolic acidosis). The mRNA of two renal Na(+)/citrate cotransporters, which were respectively expressed on apical and basolateral membrane, were measured by Northern blot with two probes, SDCT1 and SDCT2. Animals were sacrificed on day 1,3 and 7. On the 1st day, the blood plasma HCO(-)3 of acidosis group decreased significantly (P<0.01), but the mRNA abundance did not change. On the 3rd day in the acidosis group, the blood plasma HCO(-)3 increased slightly more than that on the 1st day, but was still significantly lower than that of the control group (P<0.01). Both the probes detected some increase in mRNA of brush border and basolateral Na(+)/citrate cotransporter. On the 7th day, the blood plasma HCO(-)3 of the acidosis group continuously increased and there was no significant difference between the two groups. The abundance of brush border and basolateral Na(+)/citrate cotransporter mRNA increased, but there was no difference between those of the 3rd day and the 7th day. It is concluded that metabolic acidosis can induce increase of Na(+)/citrate cotransporter mRNA, which may be responsible for hypocitraturia.

Acidosis↗
PubMed1999

Microtubule dysfunction by posttranslational nitrotyrosination of alpha-tubulin: a nitric oxide-dependent mechanism of cellular injury.

NO2Tyr (3-Nitrotyrosine) is a modified amino acid that is formed by nitric oxide-derived species and has been implicated in the pathology of diverse human diseases. Nitration of active-site tyrosine residues is known to compromise protein structure and function. Although free NO2Tyr is produced in abundant concentrations under pathological conditions, its capacity to alter protein structure and function at the translational or posttranslational level is unknown. Here, we report that free NO2Tyr is transported into mammalian cells and selectively incorporated into the extreme carboxyl terminus of alpha-tubulin via a posttranslational mechanism catalyzed by the enzyme tubulin-tyrosine ligase. In contrast to the enzymatically regulated carboxyl-terminal tyrosination/detyrosination cycle of alpha-tubulin, incorporation of NO2Tyr shows apparent irreversibility. Nitrotyrosination of alpha-tubulin induces alterations in cell morphology, changes in microtubule organization, loss of epithelial-barrier function, and intracellular redistribution of the motor protein cytoplasmic dynein. These observations imply that posttranslational nitrotyrosination of alpha-tubulin invokes conformational changes, either directly or via allosteric interactions, in the surface-exposed carboxyl terminus of alpha-tubulin that compromises the function of this critical domain in regulating microtubule organization and binding of motor- and microtubule-associated proteins. Collectively, these observations illustrate a mechanism whereby free NO2Tyr can impact deleteriously on cell function under pathological conditions encompassing reactive nitrogen species production. The data also yield further insight into the role that the alpha-tubulin tyrosination/detyrosination cycle plays in microtubule function.

Amino Acid Sequence↗
PubMed1999

Immunohistochemical methods to detect nitrotyrosine.

The immunohistochemical detection of nitrotyrosine is a robust method for detecting peroxynitrite and other reactive nitrogen species. Success depends on optimizing conditions for the particular tissue and experimental design under investigation and the use of positive and negative controls to verify specificity. The two controls of dithionite reduction and blocking with nitrotyrosine are a powerful combination to demonstrate specificity. The pathological significance of tyrosine nitration in proteins can also be approached. Generally, nitrated proteins can be isolated from diseased tissues by immunoprecipitation and Western blotting. The sites of nitration on specific proteins can be determined by mass spectrometry, which has revealed surprising specificity in which tyrosines and/or proteins are nitrated in vivo. This provides important evidence concerning the functional consequences of peroxynitrite formation in vivo.

Animals↗
PubMed1998

[Angiotensin II type 2 receptor gene deletion does not affect renin-angiotensin system].

It has been postulated that Angiotensin II type 2 receptor (AT2) functionally antagonizes type 1 (AT1) receptor. In the present study, we investigated whether gene deletion of AT2 receptor causes the compensatory chaos of renin-angiotensin system in mice. It was shown that the concentrations of Angiotensin II in plasma and kidney tissues and the expressions of renin and AT1A receptor in the AT2 gene null mice were unchanged, as compared with those in AT2 wild-type mice. This result suggests that gene deletion of AT2 receptor does not markedly impact the stability of renin-angiotensin system and the inductive function of AT2 receptor is compensated in a way remaining to be clarified.

Animals↗
PubMed1997

Superoxide dismutase catalyzes nitration of tyrosines by peroxynitrite in the rod and head domains of neurofilament-L.

Superoxide dismutase (SOD) catalyzes the nitration of specific tyrosine residues in proteins by peroxynitrite (ONOO-), which may be the damaging gain-of-function resulting from mutations to SOD associated with familial amyotrophic lateral sclerosis (ALS). We found that disassembled neurofilament-L (light subunit) was more susceptible to tyrosine nitration catalyzed by SOD in vitro. Neurofilament-L was selectively nitrated compared with the majority of other proteins present in brain homogenates. Assembled neurofilament-L was more resistant to nitration, suggesting that the susceptible tyrosine residues were protected by intersubunit contacts in assembled neurofilaments. Electrospray mass spectrometry of trypsin-digested neurofilament-L showed that tyrosine 17 in the head region and tyrosines 138, 177, and 265 in alpha-helical coil regions of the rod domain of neurofilament-L were particularly susceptible to SOD-catalyzed nitration. Nitrated neurofilament-L inhibited the assembly of unmodified neurofilament subunits, suggesting that the affected tyrosines are located in regions important for intersubunit contacts. Neurofilaments are major structural proteins expressed in motor neurons and known to be important for their survival in vivo. We suggest that SOD-catalyzed nitration of neurofilament-L may have a significant role in the pathogenesis of ALS.

Amino Acid Sequence↗
PubMed1997

Extensive tyrosine nitration in human myocardial inflammation: evidence for the presence of peroxynitrite.

OBJECTIVES: Production of nitric oxide via the cytokine-mediated activation of myocardial inducible nitric oxide synthase decreases myocardial contractility. Whether myocardial dysfunction is mediated directly by nitric oxide or indirectly through the formation of secondary reaction products, such as peroxynitrite, has not been established. Peroxynitrite, but not nitric oxide, reacts with the phenolic ring of tyrosine to form the stable product 3-nitro-L-tyrosine. Demonstration of tissue nitrotyrosine residues, therefore, infers the presence of peroxynitrite or related nitrogen-centered oxidants. DESIGN: Retrospective analysis of human autopsy specimens. SETTING: University pathology and basic science laboratories. PATIENTS: Formalin-fixed, paraffin-embedded myocardial tissue samples were obtained from 11 patients with a diagnosis of sepsis, seven patients with a diagnosis of viral myocarditis, and five control patients without clinical or pathologic cardiac disease. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Specific antibodies to nitrotyrosine were utilized to detect nitrotyrosine residues in human autopsy specimens. Cardiac tissue obtained from patients with myocarditis or sepsis demonstrated intense nitrotyrosine immunoreactivity in the endocardium, myocardium, and coronary vascular endothelium and smooth muscle. In contrast, connective tissue elements were without appreciable immunohistochemical staining. Nitrotyrosine antibody binding was blocked by coincubation with nitrotyrosine or nitrated bovine serum albumin, but not by aminotyrosine, phosphotyrosine, or bovine serum albumin. In situ reduction of tissue nitrotyrosine to aminotyrosine by sodium hydrosulfite also blocked antibody binding. Densitometric analysis of nitrotyrosine immunoreactivity demonstrated significantly higher values for specimens from myocarditis and sepsis patients when compared with control tissue specimens. CONCLUSION: These results demonstrate the formation of peroxynitrite within the myocardium during inflammatory disease states, suggesting a role for peroxynitrite in inflammation-associated myocardial dysfunction.

Adolescent↗
PubMed1995

Evidence for in vivo peroxynitrite production in human acute lung injury.

Oxidant-mediated toxicity resulting from acute pulmonary inflammation has been demonstrated in acute lung injury. A potent biological oxidant, peroxynitrite, is formed by the near diffusion-limited reaction of nitric oxide with superoxide. In addition to having hydroxyl radical-like oxidative reactivity, peroxynitrite is capable of nitrating phenolic rings, including protein-associated tyrosine residues. Nitric oxide does not directly nitrate tyrosine residues, therefore, demonstration of tissue nitrotyrosine residues infers the action of peroxynitrite or related nitrogen-centered oxidants. Lung tissue was obtained from formalin-fixed, paraffin-embedded autopsy specimens, and specific polyclonal and monoclonal antibodies to nitrotyrosine were visualized by diaminobenzidene-peroxidase staining. Acute lung injury resulted in intense staining throughout the lung, including lung interstitium, alveolar epithelium, proteinaceous alveolar exudate, and inflammatory cells. In addition, staining of the vascular endothelium and subendothelial tissues was present in those patients with sepsis-induced acute lung injury. Antibody binding was blocked by coincubation with nitrotyrosine or nitrated bovine serum albumin but not by aminotyrosine, phosphotyrosine, or bovine serum albumin. Reduction of tissue nitrotyrosine to aminotyrosine by sodium hydrosulfite also blocked antibody binding. In control specimens with no overt pulmonary disease, there was only slight staining of the alveolar septum. These results demonstrate that nitrogen-derived oxidants are formed in human acute lung injury and suggest that peroxynitrite may be an important oxidant in inflammatory lung disease.

Cadaver↗
PubMed1994

Extensive nitration of protein tyrosines in human atherosclerosis detected by immunohistochemistry.

Oxidation of lipoproteins is important for the initiation and propagation of the atherosclerotic lesion and may involve secondary oxidants derived from nitric oxide. Nitric oxide (NO) reacts at near diffusion limited rates with superoxide (O2-.) to form the strong oxidant, peroxynitrite (ONOO-). Nitration on the ortho position of tyrosine is a major product of peroxynitrite attack on proteins. Nitrotyrosine was detected in atherosclerotic lesions of formalin-fixed human coronary arteries with polyclonal and monoclonal antibodies. Binding was pronounced in and around foamy macrophages within the atheroma deposits. Nitration was also observed in early subintimal fatty streaks. Antibody binding was completely blocked by co-incubation with 10mM nitrotyrosine, but not by equivalent concentrations of aminotyrosine or phosphotyrosine. The presence of nitrotyrosine indicates that oxidants derived from nitric oxide such as peroxynitrite are generated in human atherosclerosis and may be involved in its pathogenesis.

Cell Nucleus↗