Nonhomologous end-joining proteins are required for V(D)J recombination, normal growth, and neurogenesis.
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Animals↗
Biomedical subjects
Y Gu
Publications and source records attributed to Y Gu.
Chaotic dynamics in classical s-wave helium.
Classical dynamics of s-wave helium in the case of E<0 is investigated by the geometric method. The ambiguousness of the orbits after two-electron critical collision (TECC) is eliminated by confining the motion to the fundamental domain defined by r1>r2. Scattering orbits are classified into undelayed and delayed (resonant) according to whether they can avoid the recurrence of reaction. A global Smale horseshoe on the surface of section is constructed for the case of Z=2 which implies that the bounded motion is purely chaotic and explains the onset of the chaotic (resonant) scattering when the incident energy is below a threshold. Immediately below the threshold, the probability of resonant scattering increases linearly with the energy difference. Moreover, we found that the permitted code sequences for the scattering orbits at a given incident energy are determined by the principal TECC orbit. Compared with the e-Ze- collinear helium, the s-wave helium is less chaotic and exhibits a more intricate threshold behavior.
Journal Article↗
Localization of distant urogenital system-, central nervous system-, and endocardium-specific transcriptional regulatory elements in the GATA-3 locus.
We found previously that neither a 6-kbp promoter fragment nor even a 120-kbp yeast artificial chromosome (YAC) containing the whole GATA-3 gene was sufficient to recapitulate its full transcription pattern during embryonic development in transgenic mice. In an attempt to further identify tissue-specific regulatory elements modulating the dynamic embryonic pattern of the GATA-3 gene, we have examined the expression of two much larger (540- and 625-kbp) GATA-3 YACs in transgenic animals. A lacZ reporter gene was first inserted into both large GATA-3 YACs. The transgenic YAC patterns were then compared to those of embryos bearing the identical lacZ insertion in the chromosomal GATA-3 locus (creating GATA-3/lacZ "knock-ins"). We found that most of the YAC expression sites and tissues are directly reflective of the endogenous pattern, and detailed examination of the integrated YAC transgenes allowed the general localization of a number of very distant transcriptional regulatory elements (putative central nervous system-, endocardium-, and urogenital system-specific enhancers). Remarkably, even the 625-kbp GATA-3 YAC, containing approximately 450 kbp and 150 kbp of 5' and 3' flanking sequences, respectively, does not contain the full transcriptional regulatory potential of the endogenous locus and is clearly missing regulatory elements that confer tissue-specific expression to GATA-3 in a subset of neural crest-derived cell lineages.
Animals↗
Pharmacokinetics, tissue distribution and photodynamic therapy efficacy of liposomal-delivered hypocrellin A, a potential photosensitizer for tumor therapy.
Hypocrellin A, from Hypocrella bambusae, is a novel photosensitizer of high singlet oxygen quantum yield for photodynamic therapy (PDT). Tissue distributions were studied in tumor-bearing mice as a function of time following administration. The tumor model was S-180 sarcoma transplanted into one hind leg of male Kunming mice; hypocrellin A (HA) was delivered to the mice by intravenous injection of 5 mg/kg of body weight as a suspension either as a unilamellar liposome or in dimethyl sulfoxide (DMSO)-solubilized saline. The HA was isolated from several tissues and organs, as well as tumors and peritumoral muscles and skin. Quantitation was performed by a high-performance liquid chromatographic technique with detection that utilizes the native fluorescence of HA. Independent of the delivery system, the dye was retained in tumors at higher concentrations than in normal tissues, except for kidney, liver, lung and spleen. The dye retention in tumors was high and was vehicle dependent. For the liposomal system, the maximal accumulation in tumor and maximal ratios of dye in tumor versus peritumoral muscle and skin occurred 12 h postinjection; for the DMSO saline system, the maximal ratio occurred earlier, 6 h postadministration. Liposomal delivery improved the selective accumulation of the dye in tumor with higher maximal levels in tumor and higher ratios of tumor-to-muscle and tumor-to-skin. Levels of dye were very low or not detectable in the brain. The PDT efficacy of HA in the liposome and DMSO saline systems was determined by evaluating the tumor volume regression percent. The PDT efficacy of HA in liposomes was highest when light treatment was performed at 12 h postinjection, consistent with the highest retention of HA in tumors. Similarly, the maximal PDT efficacy in DMSO saline was attained at 6 h postinjection, the highest HA retention point in tumor. Moreover, the peak PDT efficacy of HA in liposomes was much higher than that of HA in DMSO saline and even hematoporphyrin monomethylether.
Animals↗
Epidermal growth factor receptor participates in growth hormone signaling pathway in cardiac myocytes of neonatal rat.
OBJECTIVE: To examine whether growth hormone (GH) promotes the phosphorylation of epidermal growth factor (EGF) receptor and to elucidate the mechanisms by which EGF receptors were transactivated by GH stimulation. METHODS: Cultured cardiac myocytes were stimulated by GH directly or pretreated with inhibitors before GH stimulation. The phosphorylations of EGF receptor and JAK2 were examined with immunoprecipitation followed by Western blotting using anti-phosphotyrosine antibody (4G10). The activities of extracellular signal-regulated kinases (ERKs) were assayed with the method of MBP-containing gel. RESULTS: GH stimulated phosphorylation of EGF receptor in a time-dependent manner. Tyrphostin AG1478, a selective inhibitor of EGF receptor, strongly suppressed GH-induced ERK activation, while tyrphostin AG1295, a selective inhibitor of PDGF receptor, had no effects on the activation of ERKs stimulated by GH in cardiac myocytes. In addition, GH induced tyrosine phosphorylation of JAK2, a cytoplasmic protein tyrosine kinase, in cardiac myocytes. Moreover, tyrphostin B42, an inhibitor of JAK2 suppressed GH-induced phosphorylation of EGF receptor as well as GH-induced activation of ERKs in cardiac myocytes. CONCLUSIONS: GH evokes the phosphorylation of EGF receptor in cardiac myocytes through activating JAK2. Phosphorylated EGF receptor plays a critical role in GH signaling pathway leading to ERK activation in cardiac myocytes.
Animals↗
[The relation between polymorphisms of apolipoprotein B gene and atherosclerotic cerebral infarction].
OBJECTIVE: To explore the association of variance at XbaI site of apolipoprotein B (ApoB) gene and atherosclerotic cerebral infarction (ACI) in Chinese Han population. METHODS: Using polymerase chain reaction (PCR) techniques, we studied the restrict fragment length polymorphism (RFLP) at XbaI site of ApoB gene in 150 patients with ACI and 301 healthy age, sex-matched individuals from a population of Chinese Han nationality in Beijing. RESULTS: In both ACI group and control group, X-X- genotype was the most frequent one (frequency: 0.907, 0.948) and we did not find X+X+ genotype. The distribution of genotypes in the two groups was at the Hardy-Weiberg equilibriums. The frequency of rare allele X+ was significantly lower in Chinese Han than that reported in Caucasians (0.027 vs 0.418, 0.454, 0.479, P < 0.01). The higher frequency of rare allele X+ was found in the ACI group as compared with the control group (0.053 vs 0.027, P < 0.05). markedly increased levels of TC (5.3 +/- 1.3), (4.9 +/- 1.3) mmol/L (P < 0.05), and low levels of Apo-AI, Apo-AI/ApoB in the ACI group were observed (1.02 +/- 0.34), (1.26 +/- 0.40) g/L, (P < 0.01); X+X- genotype was associated with higher levels of ApoB compared with the levels of X-X- genotype in the ACI group (0.89 +/- 0.29) g/L, (0.78 +/- 0.17) g/L (P < 0.05). CONCLUSION: X+ allele of ApoB gene may be associated with ACI to some extent in the Chinese population, and presumbly through its effect on ApoB metabolism it increases the susceptibility to ACI.
Adult↗
Messenger RNA expressions of vasopressin system and aquaporin-2 in adriamycin-induced nephrotic rats and effects of astragalus membranaceus.
OBJECTIVE: To investigate the expressions of hypothalamic arginine vasopressin (AVP) mRNA, renal AVP V2 receptor mRNA, and AVP-dependent aquaporin-2 (AQP2) mRNA in rats with adriamycin-induced nephrotic syndrome. Effects of Chinese herb Astragalus membranaceus (AM) were also tested. METHODS: Sprague-Dawley rats with four weeks of adriamycin-induced nephrotic syndrome (NS) were used in this study. Another group NS + AM was set to testify the effects of AM given 0.5 g/kg daily on NS. Hypothalamic AVP mRNA expression was examined by dot blot method. Reverse transcription polymerase chain reaction was applied for detection of renal cortical and medullary V2 receptor and AQP2 mRNA. The results were normalized by mRNA of glyceraldehyde-3-phosphate dehydrogenase from the same sample. RESULTS: All rats receiving adriamycin presented typical nephrosis. No obvious difference in plasma osmolality was detected among NS, NS + AM, and normal control (NC) rats. Hypothalamic AVP mRNA expression was higher in NS rats than NC (53.59 +/- 5.49 vs 25.72 +/- 1.96, P < 0.01). AM completely reversed this up-regulated expression (21.88 +/- 1.25). In both cortex and medulla of the kidney, nephrotic rat had increased AVP V2 expressions by 169% and 55%, respectively, compared with normal control rat. The increment of expression of AQP2 mRNA was consistent with that of V2 receptor in NS rat. AM could partially however significantly correct these up-regulations of V2 and AQP2 mRNA expressions (P < 0.01). CONCLUSION: The up-regulated mRNA expressions of hypothalamic AVP, renal V2 receptor and AQP2 might play a role in edema formation in adriamycin-induced nephrotic rats. AM exerts its therapeutical effects on nephrosis partially through this mechanism.
Animals↗
[Clinical value of nocturnal SaO2 mornitoring in patients with overlap syndrome at high altitude].
OBJECTIVE: To study the nocturnal dynamic change of SaO2 in patients with overlap syndrome at high altitude, and to evaluate the value and significance of oxygen desaturation in assessing disease severity by means of polysomnography. METHODS: 13 patients with COPD and 12 with overlap syndrome were conducted nocturnal sleep, respiratory and dynamic SaO2 mornitoring. RESULTS: AHIs in the both groups were 3.7 +/- 1.3 and 35.7 +/- 12.9 respectively, and there was a significant difference between these two groups (P < 0.001). There were significant difference between these two groups in ISaO2, MSaO2, HSaO2, SIT85 and DI4(P < 0.005-0.001). There was a liner correlation between AHI and DI4. CONCLUSIONS: In patients with COPD, a suitable oxygen desaturation index has important clinical value on the preliminary selection and accurate diagnosis of SAS.
Altitude Sickness↗
[Expression and significance of human leukocyte antigen DR and intercellular adhesion molecule-1 in normal and pathological corneas].
OBJECTIVE: To study the expression of human leukocyte antigen DR (HLA-DR) and intercellular adhesion molecule-1 (ICAM-1) in normal and pathological corneas and their significance in corneal inflammation and rejection after keratoplasty. METHODS: The expression of HLA-DR and ICAM-1 were detected in 10 normal corneas and 48 pathological corneas by using immunohistochemical techniques. RESULTS: HLA-DR and ICAM-1 were not expressed or only slightly expressed in normal corneas and markedly expressed in pathological corneas, especially in inflammatory corneas. In general, HLA-DR and ICAM-1 were co-expressed in similar regions. The expression rates of HLA-DR and ICAM-1 in the 7 cases of keratoplasty rejection were higher than that in the 21 cases of non-rejection. CONCLUSION: The overexpression of HLA-DR and ICAM-1 is related to corneal inflammation and can promote the occurrence of keratoplasty rejection.
Adolescent↗
Interleukin 18 stimulates HIV type 1 in monocytic cells.
The cytokine interleukin (IL) 18 (formerly interferon gamma-inducing factor) induces the T helper type 1 response. In the present studies, IL-18 increased HIV type 1 (HIV-1) production from 5- to 30-fold in the chronically infected U1 monocytic cell line. Inhibition of tumor necrosis factor (TNF) activity by the addition of TNF-binding protein reduced IL-18-stimulated HIV-1 production by 48%. In the same cultures, IL-18-induced IL-8 was inhibited by 96%. Also, a neutralizing anti-IL-6 mAb reduced IL-18-induced HIV-1 by 63%. Stimulation of U1 cells with IL-18 resulted in increased production of IL-6, and exogenous IL-6 added to U1 cells increased HIV-1 production 4-fold over control. A specific inhibitor of the p38 mitogen-activated protein kinase reduced IL-18-induced HIV-1 by 73%, and a 50% inhibition was observed at 0.05 microM. In the same cultures, IL-8 was inhibited by 87%. By gel-shift and supershift analyses, increased binding activity of the transcription factor NF-kappaB was measured in nuclear extracts from U1 cells 1 h after exposure to IL-18. These results demonstrate induction of HIV-1 by IL-18 in a monocyte target associated with an intermediate role for TNF and IL-6, activation of p38 mitogen-activated protein kinase, and nuclear translocation of NF-kappaB.
Base Sequence↗
The zeta-Potential of Silicone Oil Droplets Dispersed in Aqueous Solutions.
An experimental method to measure the zeta-potential of small liquid droplets dispersed in another immiscible liquid was presented in this paper. Basically, a liquid droplet was held stationary in a test cell by applying a proper static electric field. An existing theory shows that the electrical force experienced by the droplet can be related to the zeta-potential of the liquid droplet. Thus the zeta-potential can be determined from the force balance among the electrical force, the gravitational force, and the buoyancy force being exerted on the stationary droplet. This electrical suspension method was applied to study the effects of pH values, ionic features, and concentrations of three electrolytes and two ionic surfactants on the zeta-potential of the silicone oil (No. 1) droplets. Copyright 1998 Academic Press.
Journal Article↗
Measurements of Contact Angles between an Oil-Water Interface and a Fiber by the ACDPAC Technique.
The ACRPAC (Analysis of Capillary Rise Profile Around a Cylinder) method was modified and extended to measure the contact angles between an oil-water interface and a fiber. Basically, the accurate image of the partial capillary depression profile was acquired and digitized by applying computer digital image processing and analysis techniques. The contact angle was determined by finding the best fit of the theoretically predicted profile, i.e., the curve representing a solution of the Laplace equation of capillarity, to the physically observed liquid-liquid interface. This analysis of the capillary depression profile around a cylinder (ACDPAC) technique was used to measure the contact angles of different water-oil interfaces on cylindrical glass fibers pre-coated with FC725. The wettability of the fiber-water-oil systems with varying oil and aqueous phases was examined. In particular, the wetting effects of a cationic surfactant cetyltrimethylammonium bromide (CTAB) and an anionic surfactant sodium dodecyl sulfate (SDS) dissolved in the aqueous phase were studied by using the ACDPAC technique. The oil phases tested were two dimethyl siloxane liquids, silicone oil A-type and silicone oil B-type. Copyright 1998 Academic Press.
Journal Article↗
Crystal structure of JNK3: a kinase implicated in neuronal apoptosis.
BACKGROUND: The c-Jun N-terminal kinases (JNKs) are members of the mitogen-activated protein (MAP) kinase family, and regulate signal transduction in response to environmental stress. Activation and nuclear localization of JNK3, a neuronal-specific isoform of JNK, has been associated with hypoxic and ischemic damage of CA1 neurons in the hippocampus. Knockout mice lacking JNK3 showed reduced apoptosis of hippocampal neurons and reduced seizure induced by kainic acid, a glutamate-receptor agonist. Thus, JNK3 may be important in the pathology of neurological disorders and is of significant medical interest. RESULTS: We report here the structure of unphosphorylated JNK3 in complex with adenylyl imidodiphosphate, an ATP analog. JNK3 has a typical kinase fold, with the ATP-binding site situated within a cleft between the N- and C-terminal domains. In contrast to other known MAP kinase structures, the ATP-binding site of JNK3 is well ordered; the glycine-rich nucleotide-binding sequence forms a beta-strand-turn-beta-strand structure over the nucleotide. Unphosphorylated JNK3 assumes an open conformation, in which the N- and C-terminal domains are twisted apart relative to their positions in cAMP-dependent protein kinase. The rotation leads to the misalignment of some of the catalytic residues. The phosphorylation lip of JNK3 partially blocks the substrate-binding site. CONCLUSIONS: This is the first JNK structure to be determined, providing a unique opportunity to compare structures from the three MAP kinase subfamilies. The structure reveals atomic-level details of the shape of JNK3 and the interactions between the kinase and the nucleotide. The misalignment of catalytic residues and occlusion of the active site by the phosphorylation lip may account for the low activity of unphosphorylated JNK3. The structure provides a framework for understanding the substrate specificity of different JNK isoforms, and should aid the design of selective JNK3 inhibitors.
Adenylyl Imidodiphosphate↗
Reduced apoptosis and cytochrome c-mediated caspase activation in mice lacking caspase 9.
Caspases are essential components of the mammalian cell death machinery. Here we test the hypothesis that Caspase 9 (Casp9) is a critical upstream activator of caspases through gene targeting in mice. The majority of Casp9 knockout mice die perinatally with a markedly enlarged and malformed cerebrum caused by reduced apoptosis during brain development. Casp9 deletion prevents activation of Casp3 in embryonic brains in vivo, and Casp9-deficient thymocytes show resistance to a subset of apoptotic stimuli, including absence of Casp3-like cleavage and delayed DNA fragmentation. Moreover, the cytochrome c-mediated cleavage of Casp3 is absent in the cytosolic extracts of Casp9-deficient cells but is restored after addition of in vitro-translated Casp9. Together, these results indicate that Casp9 is a critical upstream activator of the caspase cascade in vivo.
Animals↗
Evidence that Hsc70 negatively modulates the activation of the heme-regulated eIF-2alpha kinase in rabbit reticulocyte lysate.
The role of the heat-shock cognate protein, Hsc70, in regulating the activity of the heme-regulated eIF-2alpha kinase (HRI) in hemin-supplemented rabbit reticulocyte lysate (RRL) in response to heat and oxidative stress was examined and compared with the effect of Hsc70 on HRI activation in response to heme deficiency. Hsc70 suppressed eIF-2alpha phosphorylation and maintained the guanine nucleotide exchange activity of eIF-2B in heme-deficient RRL and in hemin-supplemented RRL exposed to elevated temperatures (42 degrees C), denatured protein (reduced carboxymethylated bovine serum albumin, RCM-BSA), oxidized glutathione or Hg2+. The ability of Hsc70 to inhibit HRI activation was mediated through its ability to inhibit the hyper-autophosphorylation of transformed HRI, which causes the hyperactivation of HRI. Maintenance of protein-synthesis rate was observed to be an unreliable indicator of the ability of Hsc70 to suppress HRI activation in response to stress. While Hsc70 completely reversed protein synthesis inhibition caused by Hg2+. Hsc70 only partially reversed translational inhibition caused by oxidized glutathione (GSSG) or heat shock. The inability of Hsc70 to fully protect protein synthesis from inhibition induced by heat shock or GSSG was due to inability of Hsc70 to protect eIF-4 E from heat-induced dephosphorylation, and its inability to protect translational elongation from GSSG-induced inhibition, respectively. Activation of HRI in heat-shocked hemin-supplemented lysate correlated with a marked decrease in the pool of Hsc70 that was available to bind RCM-BSA and the loss of the interaction of Hsc70 with HRI. These observations indicate that heat shock induced the accumulation of a sufficient quantity of Hsc70 binding substrates (e.g., denatured protein) to sequester Hsc70 and inhibit the ability of Hsc70 to suppress HRI activation. Our results indicate that Hsc70 not only negatively modulates the activation of HRI in heme-deficienct RRL, but also in hemin-supplemented RRL in response to heat and oxidative stress.
Animals↗
Ku70 is required for late B cell development and immunoglobulin heavy chain class switching.
Immunoglobulin (Ig) heavy chain (HC) class switch recombination (CSR) is a late B cell process that involves intrachromosomal DNA rearrangement. Ku70 and Ku80 form a DNA end-binding complex required for DNA double strand break repair and V(D)J recombination. Ku70(-/-) (K70T) mice, like recombination activating gene (RAG)-1- or RAG-2-deficient (R1T or R2T) mice, have impaired B and T cell development at an early progenitor stage, which is thought to result at least in part from defective V(D)J recombination (Gu, Y., K.J. Seidl, G.A. Rathbun, C. Zhu, J.P. Manis, N. van der Stoep, L. Davidson, H.L. Cheng, J.M. Sekiguchi, K. Frank, et al. 1997. Immunity. 7:653-665; Ouyang, H., A. Nussenzweig, A. Kurimasa, V.C. Soares, X. Li, C. Cordon-Cardo, W. Li, N. Cheong, M. Nussenzweig, G. Iliakis, et al. 1997. J. Exp. Med. 186:921-929). Therefore, to examine the potential role of Ku70 in CSR, we generated K70T mice that carry a germline Ig HC locus in which the JH region was replaced with a functionally rearranged VH(D)JH and Ig lambda light chain transgene (referred to as K70T/HL mice). Previously, we have shown that B cells from R1T or R2T mice carrying these rearranged Ig genes (R1T/HL or R2T/HL mice) can undergo CSR to IgG isotypes (Lansford, R., J. Manis, E. Sonoda, K. Rajewsky, and F. Alt. 1998. Int. Immunol. 10:325-332). K70T/HL mice had significant numbers of peripheral surface IgM+ B cells, which generated serum IgM levels similar to those of R2T/HL mice. However, in contrast to R2T/HL mice, K70T/HL mice had no detectable serum IgG isotypes. In vitro culture of K70T/HL B cells with agents that induce CSR in normal or R2T/HL B cells did lead to the induction of germline CH transcripts, indicating that initial signaling pathways for CSR were intact in K70T/HL cells. However, treatment with such agents did not lead to detectable CSR by K70T/HL B cells, and instead, led to cell death within 72 h. We conclude that Ku70 is required for the generation of B cells that have undergone Ig HC class switching. Potential roles for Ku70 in the CSR process are discussed.
Animals↗
Dynorphin uses a non-opioid mechanism to potentiate N-methyl-D-aspartate currents in single rat periaqueductal gray neurons.
The interaction of the endogenous K-opioid, dynorphin, with N-methyl-D-aspartate (NMDA) receptors was studied in single periaqueductal gray (PAG) cells using the whole cell patch recording technique. We have found that dynorphin A (1-17) rapidly and reversibly potentiates NMDA-activated currents in a subpopulation of PAG cells. The potentiation cannot be blocked by the non-specific opioid antagonist, naloxone, nor can it be reversed by the specific kappa-opioid antagonist, nor-BNI. In addition, the non-opioid fragment of dynorphin, dynorphin A (2-17), is effective in potentiating NMDA currents, while the specific kappa-opioid, U50,488, cannot mimic the action of dynorphin A (1-17). The non-opioid dynorphin action and the rapid onset and recovery of the potentiation are consistent with the idea that dynorphin interacts directly with NMDA receptors in PAG cells.
3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗