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C Luo

Publications and source records attributed to C Luo.

At least 127 records · Page 7Linked to original sources
PubMed1996

Normal function of the transcription factor NFAT1 in wasted mice. Chromosome localization of NFAT1 gene.

NFAT1 (NFATp), a cytosolic component of the nuclear factor of activated T cells (NFAT), is encoded by a single gene which was mapped to mouse chromosome 2 in the vicinity of the wasted (wst) locus. Although wasted mice display a severe immune disorder, they express normal levels of NFAT1 protein. The NFAT1 protein in wasted mice is properly regulated and possesses comparable DNA binding activity as that in their littermate controls. Therefore, the wasted phenotype is not due to a defect in the expression or early regulation of the NFAT1 protein.

Animals↗
PubMed1996

Interaction of calcineurin with a domain of the transcription factor NFAT1 that controls nuclear import.

The nuclear import of the nuclear factor of activated T cells (NFAT)-family transcription factors is initiated by the protein phosphatase calcineurin. Here we identify a regulatory region of NFAT1, N terminal to the DNA-binding domain, that controls nuclear import of NFAT1. The regulatory region of NFAT1 binds directly to calcineurin, is a substrate for calcineurin in vitro, and shows regulated subcellular localization identical to that of full-length NFAT1. The corresponding region of NFATc likewise binds calcineurin, suggesting that the efficient activation of NFAT1 and NFATc by calcineurin reflects a specific targeting of the phosphatase to these proteins. The presence in other NFAT-family transcription factors of several sequence motifs from the regulatory region of NFAT1, including its probable nuclear localization sequence, indicates that a conserved protein domain may control nuclear import of all NFAT proteins.

Amino Acid Sequence↗
PubMed1996

Mechanisms of transactivation by nuclear factor of activated T cells-1.

Nuclear factor of activated T cells-family proteins (NFAT1/NFATp, NFATc, NFAT3, and NFAT4/NFATx/NFATc3) play a key role in the transcription of cytokine genes and other genes during the immune response. We have defined the mechanisms of transactivation by NFAT1. NFAT1 possesses two transactivation domains whose sequences are not conserved in the other NFAT-family proteins, and a conserved DNA-binding domain that mediates the recruitment of cooperating nuclear transcription factors even when it is expressed in the absence of other regions of the protein. The activity of the NH2-terminal transactivation domain is modulated by an adjacent regulatory region that contains several conserved sequence motifs represented only in the NFAT family. Our results emphasize the multiple levels at which NFAT-dependent transactivation is regulated, and predict significant differences in the architecture of cooperative transcription complexes containing different NFAT-family proteins.

Binding Sites↗
PubMed1996

An enhanced immune response in mice lacking the transcription factor NFAT1.

Transcription factors of the NFAT family are thought to play a major role in regulating the expression of cytokine genes and other inducible genes during the immune response. The role of NFAT1 was investigated by targeted disruption of the NFAT1 gene. Unexpectedly, cells from NFAT1 -/- mice showed increased primary responses to Leishmania major and mounted increased secondary responses to ovalbumin in vitro. In an in vivo model of allergic inflammation, the accumulation of eosinophils and levels of serum immunoglobulin E were increased in NFAT1 -/- mice. These results suggest that NFAT1 exerts a negative regulatory influence on the immune response.

Amino Acid Sequence↗
PubMed1996

Calcineurin binds the transcription factor NFAT1 and reversibly regulates its activity.

NFAT1 (previously termed NFATp) is a cytoplasmic transcription factor involved in the induction of cytokine genes. We have previously shown that the dephosphorylation of NFAT1, accompanied by its nuclear translocation and increased DNA binding activity, is regulated by calcium- and calcineurin-dependent mechanisms, as each of these hallmarks of NFAT1 activation is elicited by ionomycin and blocked by the immunosuppressive drugs cyclosporin A and FK506 (Shaw, K.T.-Y., Ho, A.M., Raghavan, A., Kim, J., Jain, J., Park, J., Sharma, S., Rao, A., and Hogan, P.G. (1995) Proc. Natl. Acad. Sci. U.S.A. 92, 11205-11209). Here we show that the activation state of NFAT1 in T cells is remarkably sensitive to the level of calcineurin activity. Addition of cyclosporin A, even in the presence of ongoing ionomycin stimulation, results in rephosphorylation of NFAT1, its reappearance in the cytoplasm, and a return of its DNA binding activity to low levels. Similar effects are observed upon removal of ionomycin or addition of EGTA. We also demonstrate a direct interaction between calcineurin and NFAT1 that is consistent with a direct enzyme-substrate relation between these two proteins and that may underlie the sensitivity of NFAT1 activation to the level of calcineurin activity. The NFAT1-calcineurin interaction, which involves an N-terminal region of NFAT1 conserved in other NFAT family proteins, may provide a target for the design of novel immunosuppressive drugs.

Amino Acid Sequence↗
PubMed1996

Bacterial diversity at surface water in three locations within the Baltic sea as revealed by culture-dependent molecular techniques.

Diversity of culturable bacteria inhabiting the Baltic sea surface waters was studied in three separate locations. Based on electrophoretically separated whole cell proteins the number of operational taxonomic units (OTU) within each sampling location was high. Most of the OTUs were unique to single locations. Within each sampling location 8-22% of isolates belonged to a single OTU. Rarefaction analysis revealed that the bacterial community was more divergent at a polluted location than at clean areas. Also the most common OTUs were different in clean locations compared to the polluted site suggesting that both diversity and species composition of the bacterial community is greatly affected by pollution. The partial 16S rRNA gene sequences of the isolates of the most common OTUs are unique. Intragroup variation and an OTU-specific bacteriocin system was observed among the isolates of the second common OTU. The bacteriocin activity was linked to restriction fragment length polymorphism grouping, although additional variation correlating to geographic origin of isolates was observed.

Bacteria↗
PubMed1996

The genetic and molecular dissection of a prototypic circadian system.

A great deal is known about this archetypal circadian system, and it is likely that Neurospora will represent the first circadian system in which it will be possible to provide a complete description of the flow of information from the photoreceptor, through the components of oscillator, out to a terminal aspect of regulation. In Neurospora the strongest case has been made for there being a state variable of clock identified (Hall, 1995), it has now been shown that light resetting of the clock is mediated by the rapid light induction of the gene encoding this state variable, and a number of defined clock-regulated output genes have been identified, in two of which the clock-specific parts of the promoters have been localized. In addition to the importance of these factoids themselves, our efforts towards understanding of this system has allowed the development of tools and paradigms (e.g. Loros et al., 1989; Loros and Dunlap, 1991; Aronson et al., 1994a) that will help to pave the way for proving the identity of clock components in more complex systems, for understanding how clocks are regulated by entraining factors, and for showing how time information eventually is used to regulate the behaviors of clock cells, and of whole organisms.

Animals↗
PubMed1996

Recombinant NFAT1 (NFATp) is regulated by calcineurin in T cells and mediates transcription of several cytokine genes.

Transcription factors of the NFAT family play a key role in the transcription of cytokine genes and other genes during the immune response. We have identified two new isoforms of the transcription factor NFAT1 (previously termed NFATp) that are the predominant isoforms expressed in murine and human T cells. When expressed in Jurkat T cells, recombinant NFAT1 is regulated, as expected, by the calmodulin-dependent phosphatase calcineurin, and its function is inhibited by the immunosuppressive agent cyclosporin A (CsA). Transactivation by recombinant NFAT1 in Jurkat T cells requires dual stimulation with ionomycin and phorbol 12-myristate 13-acetate; this activity is potentiated by coexpression of constitutively active calcineurin and is inhibited by CsA. Immunocytochemical analysis indicates that recombinant NFAT1 localizes in the cytoplasm of transiently transfected T cells and translocates into the nucleus in a CsA-sensitive manner following ionomycin stimulation. When expressed in COS cells, however, NFAT1 is capable of transactivation, but it is not regulated correctly: its subcellular localization and transcriptional function are not affected by stimulation of the COS cells with ionomycin and phorbol 12-myristate 13-acetate. Recombinant NFAT1 can mediate transcription of the interleukin-2, interleukin-4, tumor necrosis factor alpha, and granulocyte-macrophage colony-stimulating factor promoters in T cells, suggesting that NFAT1 contributes to the CsA-sensitive transcription of these genes during the immune response.

Amino Acid Sequence↗
PubMed1996

[The radiobiologic characteristics of DNA polymerase beta in hepatomas].

DNA polymerase beta activity, its content and gene transcription levels in SMMC-LTNM hepatoma were investigated, using 3H-TTP incorporation, immunocytochemistry and cytoplasmic dot hybridization, respectively. The relations between the biological properties of the enzyme and DNA repair synthesis induced by gamma-ray irradiation were also studied. It was found that DNA polymerase beta activity, its content and the amount of its mRNA were much higher in hepatoma than those in normal hepatocytes (P < 0.01). Following whole-body irradiation of the nude mouse bearing SMMC-LTNM with 2 Gy of gamma ray, the polymerase beta activity in hepatoma increased temporarily and the gene transcription of the enzyme seemed to be more active. DNA polymerase beta participated in DNA repair synthesis and this effect was different between hepatoma and hepatocyte because of the biological differences of DNA polymerase beta. The results presented here indicated that DNA polymerase beta could affect radiation damage and radiotherapy of cancer.

Animals↗
PubMed1996

[Curative effect of Interfon-Alpha in children with infectious mononucleosis].

Thirty-one cases of infectious mononucleosis treated with Interfon-Alpha were reported. The dose of intramuscular injection was one million units per day for 5-7 days. The recovery course of fever, angina, lymphadenopathy and hepatosplenomegaly was much shorter in the study group than in the control group (27 cases). The results suggested that interfon-Alpha should be efficacious against EBV activity and might shorten the course of this disease.

Antiviral Agents↗
PubMed1996

[Inhibitory effects of gypenoside on rat heart and brain Na+, K+(-)ATPase activity].

The effects of gypenoside (Gyp) on the microsomal Na+, K(+)-ATPase from rat hearts and brains were investigated in comparison with ginsenoside (Gin). The results showed that Gyp could inhibit the enzyme activity rapidly and reversibly in vitro. The inhibition was in a concentration-depend manner. The IC50 of Gyp for the heart and brain was 58.79 +/- 8.05 mg/L and 52.07 +/- 6.25 mg/L, respectively. Kinetic analysis revealed that Gyp was an incompetitive inhibitor of ATP. These results suggest that the positive inotrope effect and the inhibition of CNS by Gyp are related to the in hibitory action of Gyp on the actiyily of Na+, K(+)-ATPase from hearts or brains.

Animals↗
PubMed1995

COS cell expression cloning of Pfg377, a Plasmodium falciparum gametocyte antigen associated with osmiophilic bodies.

We report the deduced protein sequence and preliminary characterization of Pfg377, a novel sexual stage antigen of Plasmodium falciparum. An initial cDNA clone (Pfg377-1) encoding the N-terminal 755 amino acids of Pfg377 was isolated by transfecting a 3D7 gametocyte cDNA library into COS7 cells and selecting using a pool of anti-Pfs230 monoclonal antibodies. The protein encoded by Pfg377-1 included an N-terminal hydrophobic signal sequence, but no apparent transmembrane anchor. Instead, the particular cDNA clone selected was fused in-frame at its 3' end with the coding sequence for the human decay acceleration factor membrane anchor, which had been deliberately placed downstream of the vector polylinker in order to attach potential fusion proteins onto the COS cell surface. Northern blots probed with the Pfg377-1 cDNA demonstrated cross-hybridization to a single approximately 9.5-kb transcript, which was present only in sexual stages, and not in a sexual stages. DNA hybridization was used to obtain a series of overlapping genomic clones which collectively yielded the complete DNA sequence for Pfg377. There are no introns within the gene, which contains a 9360-bp open reading frame and encodes a 377-kDa protein. The Pfg377 protein is highly hydrophilic, and has an essentially non-repetitive structure, with only four very limited regions of tandem repeats. The Pfg377 gene resides on chromosome 12, and immunoelectron microscopy with two different anti-Pfg377 polyclonal antisera raised against two separate recombinant sub-fragments of the protein both indicated that the antigen is located in electron-dense organelles of the gametocytes--the osmiophilic bodies--which are proposed to play a role in parasite emergence from the erythrocyte during gametocyte maturation in the Anopheles mosquito midgut. Although it was selected with anti-Pfs230 antibodies, comparison of the sub-cellular locations and protein sequences of Pfg377 and Pfs2 show them to be completely distinct antigens. We hypothesize that Pfg377-1 was initially isolated because it expresses an epitope which is recognized by (i.e., cross-reacts with) one of the anti-Pfs230 monoclonal antibodies used to select the original transfected COS cells.

Amino Acid Sequence↗
PubMed1995

Intestinal parasites in HIV-seropositive Zambian children with diarrhoea.

We undertook a study over a period of 9 months to define the frequency of parasitic infections in hospitalized children with diarrhoea between the ages of 15 months and 5 years. Every alternate day, mothers of all children admitted with diarrhoea between 09.00 hours and 12.00 hours to one of the wards of the Department of Pediatrics and Child Health of the University Teaching Hospital (UTH) in Lusaka, Zambia, were interviewed for enrollment of their children into the study. A total of 178 children with diarrhoea were enrolled in the study. Of these 44 (25 per cent) were HIV seropositive and 134 (75 per cent) were seronegative for HIV. Out of 44 HIV-seropositive patients, 20 (45 per cent) had acute diarrhoea and 24 (55 per cent) had chronic diarrhoea. Of the 134 HIV-seronegative patients, 68 had acute diarrhoea (51 per cent) and 66 (49 per cent) had chronic diarrhoea. At least one intestinal parasite was found in 34 out of the 178 children enrolled. The commonest parasites identified were Ascaris and Cryptosporidia. No associations were identified between parasite isolation and the following: age, sex, or socio-economic status. Cryptosporidium spp. was isolated from 6 out of 44 (14 per cent) HIV-seropositive children, while 8 out of 134 (6 per cent) seronegative children had the parasite (P = 0.01). HIV-seropositive children with chronic diarrhoea had significantly higher cryptosporidium identification rates than those HIV-seropositive children with acute diarrhoea [5 out of 24 (21 per cent) patients with chronic diarrhoea compared to 1 out of 20 (5 per cent) patients with acute diarrhoea; (P > or = 0.01)].(ABSTRACT TRUNCATED AT 250 WORDS)

AIDS-Related Opportunistic Infections↗
PubMed1995

Impact of the human immunodeficiency virus type-1 on common pediatric illnesses in Zambia.

The seroprevalence of HIV-1 and in-patient mortality in children with common pediatric illnesses was studied. Between October 1990 and July 1991 at the Department of Paediatrics and Child Health, University Teaching Hospital (UTH), Lusaka, Zambia, mothers of all pediatric admissions were interviewed and counselled for enrollment of their children into the study. Of a total of 1323 children seen, 1266 children (600 female and 666 male) were enrolled into the study. Pneumonia (28 per cent), malaria (24 per cent), malnutrition (18 per cent), and diarrhoea (10 per cent) constituted over 80 per cent of the total admission diagnoses. Tuberculosis (5 per cent) was the fifth commonest cause of admission (61 out of 1266 children). A total of 354 out of the 1266 (28 per cent) children were found to be seropositive for HIV-1 compared to a seroprevalence rate of 9 per cent in children attending accident and emergency for traumatic injuries (P=0.001). High HIV-1 seroprevalence rates were found in children with tuberculosis (69 per cent), malnutrition (41 per cent), pneumonia (28 per cent). and diarrhoea (24 per cent). The overall mortality in hospital among HIV-seropositive children (19 per cent) was significantly higher than those who were HIV-seronegative (9 per cent) (P = < 0.0001).

AIDS-Related Opportunistic Infections↗
PubMed1995

Mutation of the predicted p34cdc2 phosphorylation sites in NuMA impair the assembly of the mitotic spindle and block mitosis.

NuMA is a 236 kDa intranuclear protein that is distributed into each daughter cell during mitosis through association with the pericentrosomal region of the mitotic spindle. NuMA's interaction with the microtubules of the mitotic spindle is mediated through its 45 kDa carboxyl-terminal globular tail, and there is indirect evidence suggesting that NuMA's interaction with the mitotic spindle is controlled in a mitosis-specific manner. Consistent with this evidence is the fact that all four of the predicted p34cdc2 consensus phosphorylation sites in the NuMA protein are located in the carboxyl-terminal globular domain, and we demonstrate here that NuMA is phosphorylated in a mitosis-specific fashion in vivo. To test if the predicted p34cdc2 phosphorylation sites are necessary for NuMA's mitosis-specific interaction with the mitotic spindle, we have introduced mutations into the human NuMA cDNA that convert these predicted p34cdc2 phosphorylation sites from threonine or serine residues into alanine residues, and subsequently determined the cell cycle-dependent localization of these altered NuMA proteins following their expression in tissue culture cells. While none of these specific mutations in the NuMA sequence alters the faithful targeting of the protein into the interphase nucleus, mutation of threonine residue 2040 alone or in combination with mutations in other potential p34cdc2 phosphorylation sites abolishes NuMA's ability to associate normally with the microtubules of the mitotic spindle. Instead of binding to the mitotic spindle these mutant forms of NuMA concentrate at the plasma membrane of the mitotic cell. Cells expressing these mutant forms of NuMA have disorganized mitotic spindles, fail to complete cytokinesis normally, and assemble micronuclei in the subsequent interphase. These data suggest that NuMA's interaction with the microtubules of the mitotic spindle is controlled by cell cycle-dependent phosphorylation in addition to differential subcellular compartmentalization, and the characteristics of the dominant negative phenotype induced by these mutant forms of NuMA support a role for NuMA in the organization of the mitotic spindle apparatus.

Animals↗
PubMed1995

[A 3-year follow-up study of 50 children with acute lymphoblastic leukemia].

Fifty children with acute lymphoblastic leukemia were followed up for an average period of 3 3/12 years. The results showed that 19 (38%) cases were given up after diagnosis. Eight patients only received treatment irregularly for 1 year; among them, 2 discontinued therapy by themselves for 2-3 years and survived free of events, and 6 were lost, Twenty-three received treatment regularly; among them, 3 died of infection, 11 were in continuously complete remission and 9 experienced relapse. The total disease-free survival rate for mean 3 3/12 years is 42% (13/31), exclusive of the 19 given up cases. Statistical analysis indicates a higher relapse rate in those cases with lower initial glucocorticoid receptors (GCR) of peripheral blood lymphocytes.

Child↗
PubMed1995

[Anti-lipid peroxidation effects of sini decoction and its components on ischemic myocardium and the dose- and time-effects].

The complete Sini Decoction can significantly reduce the content of MDA in ischemic myocardium. Single ingredients of the decoction, such as Radix Aconoti Praeparata or Radix Glycyrrhizae, except Rhizoma Zingiberis, also have similar effect but inferior to that of the complete decoction. Under the present conditions of experiment, anti-lipid peroxidation of Sini Decoction is significant at doses ranging from 0.05 to 0.2ml/20g administered for 2-7 days at 0.1ml/(20g.d).

Animals↗