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Biomedical subjects

W Gu

Publications and source records attributed to W Gu.

At least 37 records · Page 2Linked to original sources
PubMed2001

Cortical neurogenesis in adult rats after transient middle cerebral artery occlusion.

BACKGROUND AND PURPOSE: This study explored the possible occurrence of newly generated nerve cells in the ischemic cortex of adult rats after middle cerebral artery occlusion and reperfusion. METHODS: Nine- to 10-week-old male Wistar rats were subjected to 2 hours of middle cerebral artery occlusion by the monofilament method. Rats received repeated intraperitoneal injections of the cell proliferation-specific marker 5-bromodeoxyuridine (BrdU) after stroke induction. Brain sections were processed for immunohistochemistry with an avidin-biotin complex-alkaline phosphatase and/or -peroxidase method. Brain sections processed with double-immunofluorescent staining were further scanned by confocal microscopy. RESULTS: Interspersed among the predominantly newly formed glial cells, some cells were double labeled by BrdU and 1 of the neuron-specific markers, Map-2, beta-tubulin III, and Neu N, at 30 and 60 days after stroke onset. These cells were randomly distributed throughout cortical layers II through VI, occurring with highest density in the ischemic boundary zone. Three-dimensional confocal analyses of BrdU and the neuron-specific marker Neu N confirmed their colocalization within the same cortical cells. CONCLUSIONS: This study suggests that new neurons can be generated in the cerebral cortex of adult rats after transient focal cerebral ischemia. Cortical neurogenesis may be a potential pathway for brain repair after stroke.

Animals↗
PubMed2001

[Relationship between circulating vascular cell adhesion molecule-1 and vascular complications in type 2 diabetes mellitus].

OBJECTIVE: To investigate the relationship between soluble vascular cell adhesion molecule-1 (sVCAM-1) and type 2 diabetes complicated with vascular diseases. METHODS: In 61 cases of type 2 diabetes with macrovascular or microvascular complications and 36 cases of healthy control, sVCAM-1 levels were measured in duplicate by enzyme-linked immunosorbent assay using the soluble VCAM-1 Kit (R& D Systems Ltd, Ablingdon, Oxfordshire, UK). RESULTS: sVCAM-1 levels in type 2 diabetes [(973.25 +/- 73.38) microg/L] were higher than these of healthy controls [(230.45 +/- 12.47) microg/L], P < 0.001. sVCAM-1 levels of type 2 diabetes with hypertension [(1263.99 +/- 87.00) microg/L] were higher than those of type 2 diabetes with microvascular complications [(726.57 +/- 95.40) microg/L], P < 0.001. CONCLUSION: There was a significant correlation between sVCAM-1 concentration and vascular complications of type 2 diabetes.

Aged↗
PubMed2000

Differential protein profile in the ear-punched tissue of regeneration and non-regeneration strains of mice: a novel approach to explore the candidate genes for soft-tissue regeneration.

Wound repair/regeneration is a genetically controlled, complex process. In order to identify candidate genes regulating fast wound repair/regeneration in soft-tissue, the temporal protein profile of the soft-tissue healing process was analyzed in the ear-punched tissue of regeneration strain MRL/MpJ-Fas(lpr) (MRL) mice and non-regeneration strain C57BL/6J(B6) mice using surface-enhanced laser desorption and ionization (SELDI) ProteinChip technology. Five candidate proteins were identified in which responses of MRL to the ear punch were 2-4-fold different compared to that of B6. Their corresponding genes were predicted using an antigen-antibody assay validated mass-based approach. Most of the predicted genes are known to play a role or are likely to play a role in the wound repair/regeneration. Of the five candidate proteins, the amount of the 23560 Da protein in the ear-punched tissue was significantly correlated with the rate of ear healing in six representative strains of mice, making it a good candidate for fast wound repair/regeneration. We speculate that the increased concentration of the 23560 Da protein in the wound tissue could stimulate the expression of various growth-promoting proteins and consequently speed up the wound repair/regeneration processes. Here, we have shown that examination of protein expression profile using SELDI technology, coupled with database search, is an alternative approach to search for candidate genes for wound repair/regeneration. This novel approach can be implemented in a variety of biological applications.

Animals↗
PubMed2000

Differential association of products of alternative transcripts of the candidate tumor suppressor ING1 with the mSin3/HDAC1 transcriptional corepressor complex.

The candidate tumor suppressor ING1 was identified in a genetic screen aimed at isolation of human genes whose expression is suppressed in cancer cells. It may function as a negative growth regulator in the p53 signal transduction pathway. However, its molecular mechanism is not clear. The ING1 locus encodes alternative transcripts of p47(ING1a), p33(ING1b), and p24(ING1c). Here we report differential association of protein products of ING1 with the mSin3 transcriptional corepressor complex. p33(ING1b) associates with Sin3, SAP30, HDAC1, RbAp48, and other proteins, to form large protein complexes, whereas p24(ING1c) does not. The ING1 immune complexes are active in deacetylating core histones in vitro, and p33(ING1b) is functionally associated with HDAC1-mediated transcriptional repression in transfected cells. Our data provide basis for a p33(ING1b)-specific molecular mechanism for the function of the ING1 locus.

3T3 Cells↗
PubMed2000

She2p is a novel RNA-binding protein that recruits the Myo4p-She3p complex to ASH1 mRNA.

In Saccharomyces cerevisiae, Ash1p is a specific repressor of transcription that localizes exclusively to daughter cell nuclei through the asymmetric localization of ASH1 mRNA. This localization requires four cis-acting localization elements located in the ASH1 mRNA, five trans-acting factors, one of which is a myosin, and the actin cytoskeleton. The RNA-binding proteins that interact with these cis-elements remained to be identified. Starting with the 3' most localization element of ASH1 mRNA in the three-hybrid assay, element E3, we isolated a clone corresponding to the C-terminus of She3p. We also found that She3p and She2p interact, and this interaction is essential for the binding of She3p with element E3 in vivo. Moreover, She2p was observed to bind the E3 RNA directly in vitro and each of the ASH1 cis-acting localization elements requires She2p for their localization function. By tethering a She3p-MS2 fusion protein to a reporter RNA containing MS2 binding sites, we observed that She2p is dispensable for She3p-MS2-dependent RNA localization.

Actins↗
PubMed2000

Deacetylation of p53 modulates its effect on cell growth and apoptosis.

The p53 tumour suppressor is a transcriptional factor whose activity is modulated by protein stability and post-translational modifications including acetylation. The mechanism by which acetylated p53 is maintained in vivo remains unclear. Here we show that the deacetylation of p53 is mediated by an histone deacetylase-1 (HDAC1)-containing complex. We have also purified a p53 target protein in the deacetylase complexes (designated PID; but identical to metastasis-associated protein 2 (MTA2)), which has been identified as a component of the NuRD complex. PID specifically interacts with p53 both in vitro and in vivo, and its expression reduces significantly the steady-state levels of acetylated p53. PID expression strongly represses p53-dependent transcriptional activation, and, notably, it modulates p53-mediated cell growth arrest and apoptosis. These results show that deacetylation and functional interactions by the PID/MTA2-associated NuRD complex may represent an important pathway to regulate p53 function.

Acetylation↗
PubMed2000

Targeting the chromatin-remodeling MSL complex of Drosophila to its sites of action on the X chromosome requires both acetyl transferase and ATPase activities.

Dosage compensation in Drosophila is mediated by a multiprotein, RNA-containing complex that associates with the X chromosome at multiple sites. We have investigated the role that the enzymatic activities of two complex components, the histone acetyltransferase activity of MOF and the ATPase activity of MLE, may have in the targeting and association of the complex with the X chromosome. Here we report that MLE and MOF activities are necessary for complexes to access the various X chromosome sites. The role that histone H4 acetylation plays in this process is supported by our observations that MOF overexpression leads to the ectopic association of the complex with autosomal sites.

Acetylation↗
PubMed2000

Molecular and clinical study of spinocerebellar ataxia type 7 in Chinese kindreds.

OBJECTIVE: To investigate the clinical and molecular characteristics of spinocerebellar ataxia type 7 (SCA7) in Chinese kindreds. BACKGROUND: Spinocerebellar ataxia type 7 is caused by the expansion of an unstable CAG repeat in the first exon of the SCA7 gene. METHODS: Clinical and related examinations were performed in all affected or at-risk individuals from 4 Chinese families presenting with autosomal dominant cerebellar ataxia and decreased visual acuity. The size of the (CAG)(n) array of the SCA7 gene was detected by polymerase chain reaction, polyacrylamide gel electrophoresis, and related techniques in the 4 families and 67 healthy controls. The relationship between expanded repeat number and age of onset was statistically analyzed. RESULTS: The SCA7 mutation was identified in 2 families. Clinical study revealed that great variation occurred in the age of onset, initial symptoms, and associated signs. Meanwhile, the analysis of 11 parent-child couples demonstrated the existence of marked anticipation. Some distinct retinal changes were noted in 2 affected patients. All SCA7 patients in our series exhibited expanded CAG repeats, ranging from 44 to 85 repeats, with a strong negative correlation between repeat size and age of onset. Repeat lengths of expanded alleles showed somatic mosaicism in leukocyte DNA. There were some subtle clinical differences between the SCA7-positive and -negative cases. CONCLUSIONS: Clinical variation occurred not only among the SCA7 families but also within the same kindred. Meiotic and mitotic instability of the CAG repeat in the SCA7 gene were demonstrated, and intergenerational instability of the array was associated with the clinical phenomenon of anticipation. Arch Neurol. 2000;57:1513-1518

Adolescent↗
PubMed2000

Cloning and characterization of the Dictyostelium discoideum cycloartenol synthase cDNA.

Cycloartenol synthase converts oxidosqualene to cycloartenol, the first carbocyclic intermediate en route to sterols in plants and many protists. Presented here is the first cycloartenol synthase gene identified from a protist, the cellular slime mold Dictyostelium discoideum. The cDNA encodes an 81-kDa predicted protein 50-52% identical to known higher plant cycloartenol synthases and 40-49% identical to known lanosterol synthases from fungi and mammals. The encoded protein expressed in transgenic Saccharomyces cerevisiae converted synthetic oxidosqualene to cycloartenol in vitro. This product was characterized by 1H and 13C nuclear magnetic resonance and gas chromatography-mass spectrometry. The predicted protein sequence diverges sufficiently from the known cycloartenol synthase sequences to dramatically reduce the number of residues that are candidates for the catalytic difference between cycloartenol and lanosterol formation.

Amino Acid Sequence↗
PubMed2000

The USA-derived transcriptional coactivator PC2 is a submodule of TRAP/SMCC and acts synergistically with other PCs.

PC2, the high-molecular weight constituent of the potent USA transcriptional coactivator fraction, was identified as a Mediator-like complex. Its composition resembles that of the TRAP/SMCC complex, but PC2 is distinguished by the prominent absence of the SRB10 and SRB11 kinase/cyclin pair, as well as several additional polypeptides. Furthermore, affinity-purified PC2, which lacks independent activity, acts in synergy with USA-derived coactivators PC3/topoisomerase I and PC4 to mediate the effects of a variety of activators (including VP16, the synthetic activator GAL4-AH, and the orphan nuclear receptor HNF4) and thus recapitulates partial USA coactivator function.

HeLa Cells↗
PubMed2000

Spontaneous fracture (sfx): a mouse genetic model of defective peripubertal bone formation.

A new mouse model of stage-specific bone growth failure and fracture has been recovered as an autosomal recessive mutation, designated spontaneous fracture (sfx). The sfx/sfx mice are phenotypically normal until shortly after weaning, when reduced mobility and impaired somatic growth are first noted. By 6 weeks of age, body, spleen, and thymus weights, as well as hematocrits and serum calcium, inorganic phosphate, total alkaline phosphatase, insulin-like growth factor-I, and osteocalcin levels are decreased. The sfx/sfx mice also show reduced femoral cortical density and diaphyseal circumference, as well as a paucity of mature osteoblasts on bone surfaces. Histological analyses of the femur and tibia in the mutants show subtle reduction of chondrocyte numbers in epiphyseal-plate columns, reduction of matrix, and near absence of osteoid below the differentiated chondrocytes. Trabeculae in proximal tibiae, iliacs, and vertebral bodies are sparse and thin. Cortical bone thickness of mutants is markedly thinned in all sites examined. By 7-8 weeks, radiographic films routinely show spontaneous impact fractures of the distal femur accompanied by callus formation, whereas complete fractures are less commonly observed. Volumetric bone mineral density (BMD) of mutant femurs is similar to +/? littermates in the center of the femoral diaphysis, but BMD declines as either end of the femoral diaphysis is approached. We have mapped the gene responsible for this phenotype to central Chromosome 14. Reduced bone mass, impaired bone formation, abnormalities of bone architecture, and a disposition to spontaneous fracture identify sfx/sfx mice as a useful model for understanding the mechanisms responsible for peripubertal bone formation.

Animals↗
PubMed2000

The function of PML in p53-dependent apoptosis.

The PML gene of acute promyelocytic leukaemia (APL) encodes a growth- and tumour-suppresor protein that is essential for several apoptotic signals. The mechanisms by which PML exerts its pro-apoptotic function are still unknown. Here we show that PML acts as a transcriptional co-activator with p53. PML physically interacts with p53 both in vitro and in vivo and co-localizes with p53 in the PML nuclear body (PML-NB). The co-activatory role of PML depends on its ability to localize in the PML-NB. p53-dependent, DNA-damage-induced apoptosis, transcriptional activation by p53, the DNA-binding ability of p53, and the induction of p53 target genes such as Bax and p21 upon gamma-irradiation are all impaired in PML-/- primary cells. These results define a new PML-dependent, p53-regulatory pathway for apoptosis and shed new light on the function of PML in tumour suppression.

Animals↗
PubMed2000

Early and delayed induction of immediate early gene expression in a novel focal cerebral ischemia model in the rat.

This study aimed at evaluating changes in expression of immediate early genes in a new photothrombotic focal ischemia model that exhibits late spontaneous reperfusion and morphological restoration in the region-at-risk within the cerebral cortex. Gene expression was studied with Northern blots, in situ hybridization and immunohistochemistry. At early time points (1-4 h), nerve growth factor-induced gene A and B, and c-fos mRNAs, were quickly induced throughout the ipsilateral cortex, with no obvious differences between the region-at-risk and remote cortical areas. High concentrations of nerve growth factor-induced gene A and c-Fos proteins were present within the region-at-risk even when cortical cerebral blood flow was as low as 40% of control values. At 4 h the nerve growth factor-induced gene A mRNA and protein expression was significantly decreased in the hippocampus vs. naive controls. However, a small decrease was also found in sham-operated and anaesthetized controls. A late induction, at 5 days, of c-fos and nerve growth factor-induced gene B mRNAs was seen bilaterally in the hippocampus and also, in the case of nerve growth factor induced-gene B, in the contralateral cortex. A complex pattern of changes in immediate early gene expression occurs after reversible focal cortical ischemia. This may be important for tissue recovery as well as neuropsychiatric symptoms after stroke.

Animals↗
PubMed2000

Cortical neurogenesis in adult rats after reversible photothrombotic stroke.

Neurogenesis occurs throughout life in the dentate gyrus of hippocampus and subventricular zone, but this phenomenon has rarely been observed in other brain regions of adult mammals. The aim of the current study was to investigate the cell proliferation process in the ischemically challenged region-at-risk after focal cerebral ischemia in the adult rat brain. A reversible photothrombotic ring stroke model was used, which features sustained hypoperfusion followed by late spontaneous reperfusion and a remarkable morphologic tissue recovery in the anatomically well defined somatosensory cortical region-at-risk. Twelve-week-old male Wistar rats received repeated intraperitoneal injections of the cell proliferation specific marker 5-bromodeoxyuridine (BrdU) after stroke induction. Immunocytochemistry of coronal brain sections revealed that the majority of BrdU-positive cells were of glial, macrophage, and endothelial origin, whereas 3% to 6% of the BrdU-positive cells were double-labeled by BrdU and the neuronspecific marker Map-2 at 7 and 100 days after stroke onset in the region-at-risk. They were distributed randomly in cortical layers II-VI. Three-dimensional confocal analyses of BrdU and the neuronal-specific marker Neu N by double immunofluorescence confirmed their colocalization within the same cells at 72 hours and 30 days after stroke induction. This study suggests that, as a potential pathway for brain repair, new neurons can be generated in the cerebral cortex of adult rats after sublethal focal cerebral ischemia.

Animals↗
PubMed2000

The drosophila MSL complex acetylates histone H4 at lysine 16, a chromatin modification linked to dosage compensation.

In Drosophila, dosage compensation-the equalization of most X-linked gene products in males and females-is achieved by a twofold enhancement of the level of transcription of the X chromosome in males relative to each X chromosome in females. A complex consisting of at least five gene products preferentially binds the X chromosome at numerous sites in males and results in a significant increase in the presence of a specific histone isoform, histone 4 acetylated at lysine 16. Recently, RNA transcripts (roX1 and roX2) encoded by two different genes have also been found associated with the X chromosome in males. We have partially purified a complex containing MSL1, -2, and -3, MOF, MLE, and roX2 RNA and demonstrated that it exclusively acetylates H4 at lysine 16 on nucleosomal substrates. These results demonstrate that the MSL complex is responsible for the specific chromatin modification characteristic of the X chromosome in Drosophila males.

Animals↗
PubMed2000

[Delineation of 6q deletions in breast carcinoma cell lines by fluorescence in situ hybridization].

OBJECTIVE: To detect and delineate 6q deletions in ten breast carcinoma cell lines. METHODS: Fluorescence in situ hybridization(FISH) with 37 YAC probes hybridizing from 6q12 to 6q27 and a centromeric probe of chromosome 6 as internal control. RESULTS: In five cell lines, large deletions extending from 6q12 to 6q27 were found, while a small deletion involving 6q25-6q27 was identified in one cell line. In two cell lines containing different cell populations, deletions of 6q occurred in cells with polysomy 6, but not in cells with disomy 6. In addition, an overpresentation of 6q21-q22.2 was detected in one cell line. CONCLUSION: 6q25-q27 seems to be the commonly deleted region in breast cancers and 6q deletions might be secondary changes.

Chromosome Deletion↗
PubMed2000

[The effect of fluoride-arsenic exposure on the lipid peroxidation and antioxidation of the offspring of rats].

OBJECTIVE: To provide information on the effects of the offspring of rats exposed to fluoride-arsenic. METHODS: The levels of lipid peroxidation and the abilities of antioxidation were determined in the blood of the rats and their offsprings under two generations-one nest reproductive test. RESULTS: The activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in the blood decreased with the increase of exposure dose. For example, the activity of SOD, was 14.56, 13.74, 11.89 and 11.21 micromol x min(-1) x mg Hb(-1) in different dose groups of F(2), respectively. In contrast, the concentration of lipid peroxides (LPO) increased. Eight weeks after exposure, the activities of SOD and GSH-Px increased, the activity of SOD was 13.97, 13.55, 13.47 and 12.76 micromol x min(-1) x mg Hb(-1), respectively, and the concentration of LPO returned to normal level. CONCLUSION: Fluoride-arsenic exposure can cause oxidative damage of the rat's offspring.

Animals↗