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J Kim

Publications and source records attributed to J Kim.

At least 199 records · Page 11Linked to original sources
PubMed2001

Apoptosis signal-regulating kinase 1 controls the proapoptotic function of death-associated protein (Daxx) in the cytoplasm.

Although Daxx (death-associated protein) was first reported to mediate the apoptotic signal from Fas to JNK in the cytoplasm, other data suggested that Daxx is mainly located in the nucleus as a transcriptional regulator. Here, we demonstrated that cellular localization of Daxx could be determined by the relative concentration of a proapoptotic kinase, apoptosis signal-regulating kinase 1 (ASK1) by using immunofluorescence and transcriptional reporter assay. ASK1 sequestered Daxx in the cytoplasm and inhibited the repressive activity of Daxx in transcription. In addition, Daxx was bound to the activated Fas only in the presence of ASK1, accelerating the Fas-mediated apoptosis. These results suggest that Daxx requires ASK1 for its cytoplasmic localization and Fas-mediated signaling. Taken together, we could conclude that ASK1 controls the dual function of Daxx as a transcriptional repressor in the nucleus and as a proapoptotic signal mediator in the cytoplasm.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Effects of capsaicin on Ca(2+) release from the intracellular Ca(2+) stores in the dorsal root ganglion cells of adult rats.

We have investigated the effect of capsaicin on Ca(2+) release from the intracellular calcium stores. Intracellular calcium concentration ([Ca(2+)](i)) was measured in rat dorsal root ganglion (DRG) neurons using microfluorimetry with fura-2 indicator. Brief application of capsaicin (1 microM) elevated [Ca(2+)](i) in Ca(2+)-free solution. Capsaicin-induced [Ca(2+)](i) transient in Ca(2+)-free solution was evoked in a dose-dependent manner. Resiniferatoxin, an analogue of capsaicin, also raised [Ca(2+)](i) in Ca(2+)-free solution. Capsazepine, an antagonist of capsaicin receptor, completely blocked the capsaicin-induced [Ca(2+)](i) transient. Caffeine completely abolished capsaicin-induced [Ca(2+)](i) transient. Dantrolene sodium and ruthenium red, antagonists of the ryanodine receptor, blocked the effect of capsaicin on [Ca(2+)](i). However, capsaicin-induced [Ca(2+)](i) transient was not affected by 2-APB, a membrane-permeable IP(3) receptor antagonist. Furthermore, depletion of IP(3)-sensitive Ca(2+) stores by bradykinin and phospholipase C inhibitors, neomycin, and U-73122, did not block capsaicin-induced [Ca(2+)](i) transient. In conclusion, capsaicin increases [Ca(2+)](i) through Ca(2+) release from ryanodine-sensitive Ca(2+) stores, but not from IP(3)-sensitive Ca(2+) stores in addition to Ca(2+) entry through capsaicin-activated nonselective cation channel in rat DRG neurons.

Animals↗
PubMed2001

K252a, an indrocarbazole derivative, causes the membrane of myoblasts to enter a fusion-capable state.

K252a, an indrocarbazole derivative and protein kinase inhibitor, is reported to promote myogenic differentiation in C2 mouse myoblasts. We examined the effects of K252a on QM-RSV cells, quail myoblasts transformed with a temperature-sensitive mutant of Rous sarcoma virus. K252a promoted myotube formation of QM-RSV cells. Presumptive QM-RSV cells also formed multinucleated cells when exposed to K252a. However, the expression of myogenin, a muscle regulatory factor, was not stimulated in the presence of the drug, suggesting that it promotes membrane fusion but not myogenic differentiation. To confirm the promotion of membrane fusion by K252a, presumptive C2 cells, which are strongly resistant to HVJ-mediated cell fusion, were fused by HVJ (Sendai virus) after K252a treatment. Presumptive C2 cells treated with K252a fused with HVJ, demonstrating that K252a causes the cells to enter a fusion-capable state. The amount of membrane cholesterol, a factor that decreases membrane fluidity, fell in K252a-treated C2 cells. The results suggest that a decrease of membrane cholesterol is a cause of the change that renders myoblast membrane susceptible to fusion in the presence of K252a.

Animals↗
PubMed2001

Multiple ligand interaction of alpha-synuclein produced various forms of protein aggregates in the presence of Abeta25-35, copper, and eosin.

Various protein aggregates of alpha-synuclein developed by way of the common protein self-oligomerization in the presence of Abeta25-35, copper, and eosin were examined. All the aggregates exhibited congo red birefringence although the actual amounts of the aggregates were varied as determined by thioflavin T binding fluorescence. When their morphologies were analyzed in relation to in vitro cytotoxicity, the smallest granular aggregates obtained with copper exhibited the highest cytotoxicity, while the fibrous structures by eosin did not affect the cell.

Amyloid beta-Peptides↗
PubMed2001

Mammographically detected ductal carcinoma in situ of the breast treated with breast-conserving surgery and definitive breast irradiation: long-term outcome and prognostic significance of patient age and margin status.

PURPOSE: This study was performed to determine the long-term outcome for women with mammographically detected ductal carcinoma in situ (DCIS; intraductal carcinoma) of the breast treated with breast-conserving surgery followed by definitive breast irradiation. METHODS AND MATERIALS: An analysis was performed of 422 mammographically detected intraductal breast carcinomas in 418 women from 11 institutions in North America and Europe. All patients were treated with breast-conserving surgery followed by definitive breast irradiation. The median follow-up time was 9.4 years (mean, 9.4 years; range, 0.1-19.8 years). RESULTS: The 15-year overall survival rate was 92%, and the 15-year cause-specific survival rate was 98%. The 15-year rate of freedom from distant metastases was 94%. There were 48 local failures in the treated breast, and the 15-year rate of any local failure was 16%. The median time to local failure was 5.0 years (mean, 5.7 years; range, 1.0-15.2 years). Patient age at the time of treatment and final pathology margin status from the primary tumor excision were both significantly associated with local failure. The 10-year rate of local failure was 31% for patient age < or = 39 years, 13% for age 40-49 years, 8% for age 50-59 years, and 6% for age > or = 60 years (p = 0.0001). The 10-year rate of local failure was 24% when the margins of resection were positive, 9% when the margins of resection were negative, 7% when the margins of resection were close, and 12% when the margins of resection were unknown (p = 0.030). Patient age < or = 39 years and positive margins of resection were both independently associated with an increased risk of local failure (p = 0.0006 and p = 0.023, respectively) in the multivariable Cox regression model. CONCLUSIONS: The 15-year results from the present study demonstrated high rates of overall survival, cause-specific survival, and freedom from distant metastases following the treatment of mammographically detected ductal carcinoma in situ of the breast using breast-conserving surgery and definitive breast irradiation. Younger age and positive margins of resection were both independently associated with an increased risk of local failure. The 15-year results in the present study serve as an important benchmark for comparison with other treatment modalities. These results support the use of breast-conserving surgery and definitive breast irradiation for the treatment of appropriately selected patients with mammographically detected ductal carcinoma in situ of the breast.

Adult↗
PubMed2001

A role for IL-12 receptor expression and signal transduction in host defense in leprosy.

The generation of cell-mediated immunity against intracellular infection involves the production of IL-12, a critical cytokine required for the development of Th1 responses. The biologic activities of IL-12 are mediated through a specific, high affinity IL-12R composed of an IL-12Rbeta1/IL-12Rbeta2 heterodimer, with the IL-12Rbeta2 chain involved in signaling via Stat4. We investigated IL-12R expression and function in human infectious disease, using the clinical/immunologic spectrum of leprosy as a model. T cells from tuberculoid patients, the resistant form of leprosy, are responsive to IL-12; however, T cells from lepromatous patients, the susceptible form of leprosy, do not respond to IL-12. We found that the IL-12Rbeta2 was more highly expressed in tuberculoid lesions compared with lepromatous lesions. In contrast, IL-12Rbeta1 expression was similar in both tuberculoid and lepromatous lesions. The expression of IL-12Rbeta2 on T cells was up-regulated by Mycobacterium leprae in tuberculoid but not in lepromatous patients. Furthermore, IL-12 induced Stat4 phosphorylation and DNA binding in M. leprae-activated T cells from tuberculoid but not from lepromatous patients. Interestingly, IL-12Rbeta2 in lepromatous patients could be up-regulated by stimulation with M. tuberculosis. These data suggest that Th response to M. leprae determines IL-12Rbeta2 expression and function in host defense in leprosy.

Antigens, Bacterial↗
PubMed2001

Human chromosome 19 and related regions in mouse: conservative and lineage-specific evolution.

To illuminate the function and evolutionary history of both genomes, we sequenced mouse DNA related to human chromosome 19. Comparative sequence alignments yielded confirmatory evidence for hypothetical genes and identified exons, regulatory elements, and candidate genes that were missed by other predictive methods. Chromosome-wide comparisons revealed a difference between single-copy HSA19 genes, which are overwhelmingly conserved in mouse, and genes residing in tandem familial clusters, which differ extensively in number, coding capacity, and organization between the two species. Finally, we sequenced breakpoints of all 15 evolutionary rearrangements, providing a view of the forces that drive chromosome evolution in mammals.

Animals↗
PubMed2001

Prevalence of the enteroaggregative Escherichia coli heat-stable enterotoxin 1 (EAST1) gene in isolates in weaned pigs with diarrhea and/or edema disease.

A total of 476 Escherichia coli isolated from weaned pigs with diarrhea and/or edema disease were screened for the presence of the enteroaggregative E. coli heat-stable enterotoxin 1 (EAST1) gene by polymerase chain reaction (PCR). E. coli strains that carried EAST1 genes were also tested by PCR for the presence of genes for five fimbriae (F4, F5, F6, F18 and F41), two heat-stable (STa and STb) and one heat-labile (LT) enterotoxin, and Shiga toxin 2e (Stx2e). One hundred and forty nine (31.3%) of the 476 E. coli isolates carried the gene for EAST1. Of these 149 isolates, 66 (44.3%) carried the east1 gene only and 83 (55.7%) carried genes for the fimbrial adhesins or enterotoxins. E. coli which carried east1 gene also possessed genes for STa or F4 frequently. EAST1 may represent an additional determinant in the pathogenesis of E. coli diarrhea in weaned pigs.

Animals↗
PubMed2001

A rapid screen for putative mislocalization mutations by using a GAL4-hybrid protein.

A GAL4 one-hybrid system was used to develop an indirect assay for intracellular localization. The Kar1 protein, a component of the yeast spindle pole body (SPB), was shown to be targeted to the SPB by electron microscopic analysis, or indirect immunofluorescence methods. To assay localization of the Kar1p by measuring the reporter gene expression on solid media, we constructed Kar1-Gal4 hybrid proteins with or without the SPB localization domain. The long fusion Kar1(299)-Gal4 with the localization domain led to non-growth on SC-His + AT media, and quite a low level of the lacZ reporter gene expression. The short fusion Kar1(107)-Gal4 without the localization domain caused a full activation of the reporter genes, HIS3 and lacZ, indicating that the protein remains in the nucleoplasm. These results suggest that the Kar1(299)-Gal4p fusion protein, localized to the SPB, can be clearly differentiated with the mislocalized protein by assaying the reporter gene expression. By utilizing the Kar1(299)-Gal4 construct, we isolated ten spontaneous mutations that were defective in the Kar1-Gal4p localization. Four of these mutations were in the same complementation group. We propose, therefore, that the Gal4-hybrid localization assay can be utilized in cases where the target organelle or the structure is too small for microscopic analysis, or in the initial screening for mutations defective in localization.

DNA-Binding Proteins↗
PubMed2001

Control of conformational and interpolymer effects in conjugated polymers.

The role of conjugated polymers in emerging electronic, sensor and display technologies is rapidly expanding. In spite of extensive investigations, the intrinsic spectroscopic properties of conjugated polymers in precise conformational and spatial arrangements have remained elusive. The difficulties of obtaining such information are endemic to polymers, which often resist assembly into single crystals or organized structures owing to entropic and polydispersity considerations. Here we show that the conformation of individual polymers and interpolymer interactions in conjugated polymers can be controlled through the use of designed surfactant poly(p-phenylene-ethynylene) Langmuir films. We show that by mechanically inducing reversible conformational changes of these Langmuir monolayers, we can obtain the precise interrelationship of the intrinsic optical properties of a conjugated polymer and a single chain's conformation and/or interpolymer interactions. This method for controlling the structure of conjugated polymers and establishing their intrinsic spectroscopic properties should permit a more comprehensive understanding of fluorescent conjugated materials.

Journal Article↗
PubMed2001

Hydrogen peroxide is a novel inducer of connective tissue growth factor.

Connective tissue growth factor (CTGF) has recently been described as a fibrogenic factor and is greatly induced by various extracellular stimuli, such as transforming growth factor-beta (TGF-beta), dexamethasone, and serotonin. CTGF induces collagen type I and fibronectin, and the deposition of such molecules leads to fibrotic disease in many tissues. Intracellular reactive oxygen species (ROS) are generated by extracellular stress conditions and are produced as by-products of cellular metabolism. Imbalanced cellular redox status is a potent pathogenic factor that leads to various degenerative diseases, including tissue fibrosis. Since CTGF is believed to play a crucial role in fibrotic disease formation in many tissues, we examined the role of ROS in CTGF gene expression in human lens epithelial cell line B3. The results showed that CTGF was induced by reactive oxygen species such as hydrogen peroxide and hydroxyl radicals. Next, we examined whether CTGF induction by ROS is via newly synthesized TGF-beta. The results showed that ROS directly induced CTGF mRNA not via the increased TGF-beta synthesis or activation. Next, we treated AG490, which is the well-known inhibitor of Janus kinase (JAK), with hydrogen peroxide. AG490 abrogated the CTGF induction by ROS in a dose-dependent manner. The results suggest that JAK-2/-3 seems to be involved in the enhanced CTGF mRNA expression by hydrogen peroxide. In this report, we present that hydrogen peroxide is a novel inducer of CTGF gene expression and that JAK-2/-3 activation seems to play a role in CTGF induction.

Amino Acid Sequence↗
PubMed2001

Homology-driven assembly of a sequence-ready mouse BAC contig map spanning regions related to the 46-Mb gene-rich euchromatic segments of human chromosome 19.

Draft sequence derived from the 46-Mb gene-rich euchromatic portion of human chromosome 19 (HSA19) was utilized to generate a sequence-ready physical map spanning homologous regions of mouse chromosomes. Sequence similarity searches with the human sequence identified more than 1000 individual orthologous mouse genes from which 382 overgo probes were developed for hybridization. Using human gene order and spacing as a model, these probes were used to isolate and assemble bacterial artificial chromosome (BAC) clone contigs spanning homologous mouse regions. Each contig was verified, extended, and joined to neighboring contigs by restriction enzyme fingerprinting analysis. Approximately 3000 mouse BACs were analyzed and assembled into 44 contigs with a combined length of 41.4 Mb. These BAC contigs, covering 90% of HSA19-related mouse DNA, are distributed throughout 15 homology segments derived from different regions of mouse chromosomes 7, 8, 9, 10, and 17. The alignment of the HSA19 map with the ordered mouse BAC contigs revealed a number of structural differences in several overtly conserved homologous regions and more precisely defined the borders of the known regions of HSA19-syntenic homology. Our results demonstrate that given a human draft sequence, BAC contig maps can be constructed quickly for comparative sequencing without the need for preestablished mouse-specific genetic or physical markers and indicate that similar strategies can be applied with equal success to genomes of other vertebrate species.

Animals↗
PubMed2001

Rat embryo fibroblasts require both the cell-binding and the heparin-binding domains of fibronectin for survival.

Fibronectin (FN) is known to transduce signal(s) to rescue cells from detachment-induced apoptosis (anoikis) through an integrin-mediated survival pathway. However, the functions of individual FN domains have not been studied in detail. In the present study we investigated whether the interaction of the cell-binding domain of FN with integrin is sufficient to rescue rat embryo fibroblasts (REFs) from detachment-induced apoptosis. REFs attached and spread normally after plating on substrates coated with either intact FN or a FN fragment, FN120, that contains the cell-binding domain but lacks the C-terminal heparin-binding domain, HepII. REFs on FN maintained a well-spread fibroblastic shape and even proliferated in serum-free medium at 20 h after plating. In contrast, previously well-spread REFs on FN120 started losing fibroblastic shape with time and detached from FN120-coated plates after approx. 8 h. Nuclear condensation indicated apototic cell death. This was due to the decreased activity/stability of focal adhesion kinase (pp125FAK) in the absence of HepII domain. A peptide in the HepII domain [peptide V, WQPPRARI (single-letter amino acid codes)], which has previously been implicated in cytoskeletal organization, rescued apoptotic changes. Consistently, pp125FAK phosphorylation was increased, and both cleavage of pp125FAK and activation of caspase 3 on FN120 were partly blocked by peptide V. Thus the interaction of the cell-binding domain with integrin has a major role in cell survival but is itself not sufficient for cell survival. One or more additional survival signals come from the HepII domain to regulate pp125FAK activity/stability.

Amino Acid Sequence↗
PubMed2001

Apg2 is a novel protein required for the cytoplasm to vacuole targeting, autophagy, and pexophagy pathways.

To survive starvation conditions, eukaryotes have developed an evolutionarily conserved process, termed autophagy, by which the vacuole/lysosome mediates the turnover and recycling of non-essential intracellular material for re-use in critical biosynthetic reactions. Morphological and biochemical studies in Saccharomyces cerevisiae have elucidated the basic steps and mechanisms of the autophagy pathway. Although it is a degradative process, autophagy shows substantial overlap with the biosynthetic cytoplasm to vacuole targeting (Cvt) pathway that delivers resident hydrolases to the vacuole. Recent molecular genetics analyses of mutants defective in autophagy and the Cvt pathway, apg, aut, and cvt, have begun to identify the protein machinery and provide a molecular resolution of the sequestration and import mechanism that are characteristic of these pathways. In this study, we have identified a novel protein, termed Apg2, required for both the Cvt and autophagy pathways as well as the specific degradation of peroxisomes. Apg2 is required for the formation and/or completion of cytosolic sequestering vesicles that are needed for vacuolar import through both the Cvt pathway and autophagy. Biochemical studies revealed that Apg2 is a peripheral membrane protein. Apg2 localizes to the previously identified perivacuolar compartment that contains Apg9, the only characterized integral membrane protein that is required for autophagosome/Cvt vesicle formation.

Autophagy-Related Proteins↗
PubMed2001

Evidence of two distinct subsubtypes within the HIV-1 subtype A radiation.

Members of HIV-1 group M are responsible for the vast majority of AIDS cases worldwide and have been classified on the basis of their phylogenetic relationships into nine roughly equidistant clades, termed subtypes. Although there are no known phenotypic correlates for these genotypes, the disproportionate spread of certain of these lineages has been taken to indicate that subtype-specific biological differences may exist. The subtype nomenclature thus remains an important molecular epidemiological tool with which to track the course of the group M pandemic. In this study, we have characterized HIV-1 strains described previously as unusual subtype A variants on the basis of partial sequence analysis. Six such strains from Cyprus (CY), South Korea (KR), and the Democratic Republic of Congo (CD) were PCR amplified from infected cell culture or patient PBMC DNA, cloned, and sequences in their entirety (94CY017, 97KR004, 97CDKTB48, and 97CDKP58) or as half genomes (97CDKS10 and 97CDKFE4). Distance and phylogenetic analyses showed that four of these viruses (94CY017, 97CDKTB48, 97CDKFE4, and 97CDKS10) were closely related to each other, but quite divergent from all other HIV-1 strains, except for subtype A viruses, which represented their closest relatives. In phylogenetic trees from gag, pol, env, and nef regions, the four newly characterized HIV-1 strains formed a distinct sister clade to subtype A, which was as closely related to subtype A as subsubtypes F1 and F2 are to each other. According to current nomenclature rules, this defines a subsubtype, which we have tentatively termed A2. The two other viruses, 97KR004 and 97CDKP58, as well as a full-length HIV-1 sequence from the sequence database (ZAM184), were found to represent complex A2/D, A2/G, and A2/C recombinants, respectively. These results indicate that HIV-1 subtype A is composed of two subsubtypes (A1 and A2), both of which appear to have a widespread geographic distribution. The A2 viruses described here represent the first reference reagents for this new group M lineage.

Cyprus↗
PubMed2001

Drosophila phosphoinositide-dependent kinase-1 regulates apoptosis and growth via the phosphoinositide 3-kinase-dependent signaling pathway.

Phosphoinositide-dependent kinase-1 (PDK-1) is a central mediator of the cell signaling between phosphoinositide 3-kinase (PI3K) and various intracellular serine/threonine kinases including Akt/protein kinase B (PKB), p70 S6 kinases, and protein kinase C. Recent studies with cell transfection experiments have implied that PDK-1 may be involved in various cell functions including cell growth and apoptosis. However, despite its pivotal role in cellular signalings, the in vivo functions of PDK-1 in a multicellular system have rarely been investigated. Here, we have isolated Drosophila PDK-1 (dPDK-1) mutants and characterized the in vivo roles of the kinase. Drosophila deficient in the dPDK-1 gene exhibited lethality and an apoptotic phenotype in the embryonic stage. Conversely, overexpression of dPDK-1 increased cell and organ size in a Drosophila PI3K-dependent manner. dPDK-1 not only could activate Drosophila Akt/PKB (Dakt1), but also substitute the in vivo functions of its mammalian ortholog to activate Akt/PKB. This functional interaction between dPDK-1 and Dakt1 was further confirmed through genetic analyses in Drosophila. On the other hand, cAMP-dependent protein kinase, which has been proposed as a possible target of dPDK-1, did not interact with dPDK-1. In conclusion, our findings provide direct evidence that dPDK-1 regulates cell growth and apoptosis during Drosophila development via the PI3K-dependent signaling pathway and demonstrate our Drosophila system to be a powerful tool for elucidating the in vivo functions and targets of PDK-1.

3-Phosphoinositide-Dependent Protein Kinases↗