[Isolation of a development revertant of Myxococus Xamthus]

fruA::Tc omega 5 is a development deficient strain of M. Xamthus. Transposon TnV was used to randomly mutagenize various sites of fruA::Tc omega 5 chromosome. Fruiting body formation was restored in one TnV insertion mutant, designated XM1206. The TnV-inserted DNA fragment from XM1206 chromosome was cloned, which may be served as a probe to isolate the corresponding allele from wild-type strain.

Modulation of BmKAS-1 and BmK1-3-2 to sodium channel in rat dorsal root ganglion neurons

OBJECTIVE

To investigate what effects BmKAS-1 (a polypeptide purified from the Chinese scorpion Buthus martensi Karsch [BmK] and named as BmK activator of skeletal-muscle ryanodine receptor) and its upstream mixture BmK1-3-2 have on Na+ channels in dorsal root ganglion (DRG) small diameter neurons.

METHODS

The whole-cell patch-clamp technique was used to investigate the effects of BmKAS-1 and BmK1-3-2 on Na+ current in rat small diameter DRG neurons.

RESULTS

About 50% peak Na+ current was suppressed by 10 micrograms/ml of BmK1-3-2. 1.62 micrograms/ml of BmKAS-1 also blocked 50% peak Na+ current, and there was an obvious dose-dependent relationship.

CONCLUSION

Both BmK1-3-2 and BmKAS-1 have a blocking effect on Na+ channels, and this may one of the mechanisms for the analgetic effect of BmK1-3-2 and BmKAS-1.

Metabolic changes in rats with photochemically induced cerebral infarction and the effects of batroxobin: a study by magnetic resonance imaging, 1H- and 31P-magnetic resonance spectroscopy

Metabolic changes in rats with photochemically induced cerebral infarction and the effects of batroxobin were investigated 1, 3, 5 and 7 days after infarction by means of magnetic resonance imaging (MRI), 1H- and 31P-magnetic resonance spectroscopy (MRS). A region of T2 hyperintensity was observed in left temporal neocortex in infarction group and batroxobin group 1, 3, 5 and 7 days after infarction. The volume of the region gradually decreased from 1 day to 7 days after infarction. The ratio of NAA/Cho + Cr in the region of T2 hyperintensity in the infarction group was significantly lower than that in the corresponding region in the sham-operated group 3, 5 and 7 days after infarction respectively (P < 0.05). Lac appeared in the region of T2 hyperintensity in the infarction group 1, 3, 5 and 7 days after infarction, but it was not observed in the corresponding region in sham-operated group at all time points. Compared with the sham-operated group, the ratios of beta ATP/PME + PDE and PCr/PME + PDE of the whole brain in the infarction group were significantly lower 1, 3 and 5 days after infarction respectively (P < 0.05), and the ratio of beta ATP/PCr also was significantly lower 1 day after infarction (P < 0.05). Batroxobin significantly decreased the volume of the region of T2 hyperintensity 1 and 3 days after infarction (P < 0.05), significantly increased the ratio of NAA/Cho + Cr in the region 5 and 7 days after infarction (P < 0.05), significantly decreased the ratios of Lac/Cho + Cr and Lac/NAA in the region 5 and 7 days after infarction (P < 0.05), and significantly increased the ratios of beta ATP/PME + PDE and beta ATP/PCr in the whole brain 1 day after infarction (P < 0.05). The results indicated that the infracted region had severe edema, increased Lac and apparent neuronal dysfunction and death, and energy metabolism of the whole brain decreased after focal infarction, and that batroxobin effectively ameliorated the above-mentioned abnormal changes.

The inhibitory effects of BmK IT2, a scorpion neurotoxin on rat nociceptive flexion reflex and a possible mechanism for modulating voltage-gated Na(+) channels

Buthus martensi Karsch IT2 (BmK IT2), a scorpion neurotoxin, was found to display a biphasic inhibitory effect on the C component of the rat nociceptive flexion reflex by subcutaneous injection in vivo, and also on the total Na(+) currents of rat dorsal root ganglion neurons using whole-cell patch clamping. BmK IT2 blocked the tetrodotoxin-resistant (TTX-R) component of the Na(+) currents with a degree of selectivity. The partial block of the TTX-R Na(+) currents, brought about by 0.01 microg/microl BmK IT2, reversed less rapidly and completely than the partial block of the tetrodotoxin-sensitive (TTX-S) current brought about by the same concentration of BmK IT2. These results suggest that the inhibition of the rat nociceptive flexion reflex by BmK IT2 may be attributed to modulation of the different voltage-gated Na(+) channels.

[Inhibition of voltage-activated outward delayed rectifier potassium channel currents in dorsal root ganglion neurons of rats by lead]

OBJECTIVE

To study the effect of lead on voltage-activated outward delayed rectifier potassium channel currents in acute isolated dorsal root ganglion (DRG) neurons of adult rats.

METHODS

Patch clamp technique was employed to record the whole cell of DRG in adult rats.

RESULTS

In the experiments, delayed rectifier (IK) potassium currents channel was recorded and activation was voltage-dependent. The threshold concentration of lead (Pb2+) for IK was 1 mumol/L, which reduced potassium current by (8.6 +/- 0.8)%, 4 mumol/L of Pb2+ reduced the current by (38.6 +/- 6.2)%, and 8 mumol/L of Pb2+ reduced the current by (63.0 +/- 5.1)%. The action of lead was rapid and its effect would be reversed rapidly to various extent by washing.

CONCLUSION

Higher outward delayed rectifier potassium channel currents, which could be reversed.

Molecular cloning and genomic organization of a K(+) channel toxin from the Chinese scorpion Buthus martensii Karsch

A full-length cDNA encoding the precursor of a K(+) channel toxin (BmTX2) was first isolated from a venom-gland cDNA library of the Chinese scorpion Buthus martensii Karsch. The precursor is composed of a signal peptide of 21 residues and a mature toxin of 37 residues with three disulfide bridges. The genomic gene of BmTX2 was also cloned and sequenced. It consisted of two exons, disrupted by an intron of 81 bp inserted in the region encoding signal peptide.

Molecular cloning and sequence analysis of cDNAs encoding a beta-toxin-like peptide and two MkTx I homologues from scorpion Buthus martensii Karsch

Three full-length cDNAs, one encoding the precursor of a beta-toxin-like peptide (named BmKBT) and the other two encoding those of (MkTx I) homologues (named MkTx II and MkTx III, respectively), were isolated from a venom gland cDNA library of the Chinese scorpion Buthus martensii Karsch, by screening with a cDNA fragment generated by PCR. The encoded precursor of BmKBT contained 83 amino acid residues including a signal peptide of 19 residues, a mature peptide of 63 residues and an extra basic residue (Lys) which have to be removed in the processing step. The deduced amino acid sequence of BmKBT showed 52% homology to that of beta-neurotoxin TsVII isolated from scorpion Tityus serrulatus. However, the positions of disulfide bridges have a little variation between the two peptides. The precursors of MkTx II and MkTx III both contained 85 amino acid residues including a signal peptide of 19 residues, a mature peptide of 64 residues and two extra residues (Gly-Arg) which have to be removed in the processing step, too. There was high sequence similarity (90%) between the two peptides. The sequences of mature MkTx II and MkTx III were highly homologous with MkTx I isolated from scorpion Buthus martensii Karsch, both showing 90% identities.

Buthus martensi Karsch agonist of skeletal-muscle RyR-1, a scorpion active polypeptide: antinociceptive effect on rat peripheral nervous system and spinal cord, and inhibition of voltage-gated Na(+) currents in dorsal root ganglion neurons

The antinociceptive effect and potential antinociceptive mechanism of Buthus martensi Karsch agonist of skeletal-muscle RyR-1 (BmK AS-1), a scorpion venom derived neurotoxic polypeptide, have been investigated in rats. The results show that: (a) the withdrawal latency to rat plantar radiant heat was increased significantly by 100 and 150% after intrathecal injection of 0.6 and 1.2 microg doses; (b) C components of rat nociceptive flexion reflex were reduced to 72, 50 and 29% after intraplantar injection of 5, 10 and 20 microg doses; (c) both central (spinal cord) and peripheral antinociceptive effects of BmK AS-1 could not be reversed by naloxone; (d) tetrodotoxin-resistant (TTX-R) Na(+) current was depressed to 83.87+/-1.64, 64.73+/-5.43 and 15.85+/-17.63%, and tetrodotoxin-sensitive (TTX-S) Na(+) current was depressed to about 81.27+/-2.5, 49.08+/-8.09 and 9.03+/-12.34% with 0.2, 1.0 and 10 microg/ml BmK AS-1 measured using patch clamp recording in rat small dorsal root ganglion (DRG) neurons, respectively. The results indicate that BmK AS-1 may be a new component with potent antinociceptive activity mediated by modulating TTX-S and TTX-R Na(+) channels.

CpG oligodeoxynucleotide vaccination suppresses IgE induction but may fail to down-regulate ongoing IgE responses in mice

Antigen-specific IgE plays an important role in the pathogenesis of allergic disorders. Immunostimulatory CpG motifs (CpG) in bacterial DNA or synthesized oligodeoxynucleotides (ODN) are gaining recognition as potential immunomodulators for switching on protectiveT(h)1-mediated immunity and preventing or potentially inhibiting T(h)2-dependent allergic responses. To date, allergic models used in CpG ODN studies have been established by immunization of mice with allergen in the presence of adjuvant. This, in addition to failure to assess specific IgE production in most of the studies, has limited understanding of the role of CpG ODN vaccination in allergic responses. Here, we examine the effects of synthesized CpG ODN on both developing and ongoing IgE responses in mice sensitized using a recombinant mosquito salivary antigen (rAed a 2) without adjuvant. Pretreatment of mice with CpG ODN mixed with rAed a 2 successfully inhibited subsequent induction of serum rAed a 2-specific IgE (but not IgG1) and antigen-induced IL-4 and IL-5 production in spleen cells. This was associated with an increase of serum IgG2a and IL-12, and increased IFN-gamma and IL-12 production by spleen cells. In this model, however, co-administration of CpG ODN with rAed a 2 to presensitized mice failed to down-regulate ongoing IgE responses despite significant up-regulation of serum IL-12 and specific IgG2a. Strikingly, a transient skin delayed-type hypersensitivity reaction occurred in CpG ODN-treated mice. These observations provide a new insight into the potential therapeutic application of CpG ODN to allergic disorders.

Activation of EGFP expression by Cre-mediated excision in a new ROSA26 reporter mouse strain

Reporter mouse strains are important tools for monitoring Cre recombinase-mediated excision in vivo. In practice, excision may be incomplete in a given population due to threshold level or variegated expression of Cre. Hence, it is desirable in many experimental contexts to isolate cells that have undergone excision to assess the consequences of gene ablation. To generate alternative reporter mice, an enhanced green fluorescent protein (EGFP) gene was targeted to the retroviral-trapped ROSA26 locus. Upon Cre-mediated excision of "Stop" sequences, EGFP was expressed ubiquitously during embryogenesis and in adult tissues (including T cells, B cells, and myeloid cells). Using this new reporter strain, separation of excised from nonexcised cells in vitro was achieved in thymocytes in a noninvasive manner based on activated EGFP expression. This new EGFP reporter strain should facilitate a variety of conditional gene-targeting experiments, including the functional studies of hematopoietic cells in lineage-specific knockout mice.

[Effect of physical and chemical factors on Macaca Mulatta's pulp and change of the collagen in pulp]

OBJECTIVE

To investigate the change of pulp and its collagen to outside stimuli.

METHODS

51 permanent teeth from 10 adult healthy Macaca Mulatta's monkeys were chosen as experimental teeth. 39 of them were prepared Class V cavities. The teeth were divided into two groups, one was filled with zinc phosphate cement and another group with zinc oxide eugenol. A blank control group of 12 teeth was set at the same time. Just after the operation, 3 d, 7 d, 1 month and 3 months later, the animals were executed. Histologic changes were evaluated by means of HE and collagen staining method.

RESULTS

Local inflammation was the major representation in the pulps of the zinc phosphate cement group from 7 d to 3 months after operation. The percentage of collagen decrease dropped sharply, and there was no inflammation cells infiltration in the pulps of zinc oxide eugenol group from 1 to 3 months after operation. By means of collagen staining method, the morphological characters, distribution and the change of pulpal collagen during a certain pathologic process were clearly represented in histologic slices. The change of collagen appeared earlier than the inflammation cells infiltration.

CONCLUSIONS

Zinc phosphate cement can lead to medium inflammation of the pulp. The change of collagen appears earlier than that of WBC, which can be used as a sensitive indicator.

Cloning of differentially expressed sequence tags from nickel-transformed human embryonic lung cells

Differential display polymerase chain reaction (DD-PCR) was used to analyze the differentially expressed genes from nickel-transformed human embryonic lung (HEL) cells (MRC-9 and IMR-90) and their control counterparts (non-treated). Two genes, MS515 and IC82, were confirmed by Northern blot analysis. MS515 was detected in control and nickel oxide (NiO)-transformed MRC-9 cells, as well as in non-small cell lung cancer (NSCLC) EBC-1 cells, while very weak expression was observed in nickel subsulfide (Ni(3)S(2))-transformed MRC-9 cells and small cell lung cancer (SCLC) SBC-2 cells. IC82 could not be detected in control IMR-90 cells, while it was expressed in EBC-1 cells and NiO- and Ni(3)S(2)-transformed IMR-90 cells. These findings indicate that individual nickel compounds have their own target gene(s) in inducing lung cancer. Sequencing analyses showed that the MS515 gene shared a high degree of homology (over 80%) with the gene Mena, which is involved in actin polymerization. IC82 showed 99% homology with human chromosome 4 clone C0440E08 and a coding sequence in the brain. The roles of these two genes in nickel carcinogenesis will be discussed.

Nine novel precursors of Buthus martensii scorpion alpha-toxin homologues

The cDNAs encoding nine novel alpha-toxin homologues were isolated from the venom gland cDNA library of the Chinese scorpion Buthus martensii Karsch (BmK). They are rich in AAAA and TTTT elements at the 5' UTRs. The flanking region of the translation initiation codon ATG is AAAATGAA, which is highly conserved in scorpion Na(+), K(+) and Cl(-) channel toxin genes. These putative scorpion alpha-toxins shared 45.5-98.4% homology with the characterized BmK alpha-toxins, and were completely conserved in the positions of all eight cysteines. This showed, together with higher homology at nucleotide level than that at amino acid level, that these toxins may originate from a common ancestor. The discovery of a series of homologues of scorpion alpha-toxin with a different degree of natural mutation in the primary structure will provide us with a valuable system for studying the structure-function relationship of scorpion toxins.

Tetrandrine inhibits inward rectifying potassium current in cultured bovine aortic endothelial cells

AIM

To study the effect of tetrandrine (Tet) on inward rectifying potassium current in cultured bovine aortic endothelial cells.

METHODS

Inward rectifying potassium current (IRK) was observed by the whole cell patch-clamp technique.

RESULTS

IRK was inhibited by Tet in a concentration-dependent manner and recovered to normal after wash with drug-free external solution. IRK was reduced from (582 +/- 48) pA to (221 +/- 40) pA at a holding potential of -70 mV by Tet 30 mumol/L. IC50 was 2.8 mumol/L.

CONCLUSION

Tet inhibited inward rectifying potassium current in cultured bovine aortic endothelial cells.

Blood eicosanoids and immune indices during fasciolosis in water buffaloes

The effects of trickle infections of water buffaloes with Fasciola hepatica (60 metacercariae daily during a period of 20 days) on the blood plasma levels of prostaglandin E(2) (PGE2), 6-keto-prostaglandin F(1alpha) (6-keto-PG F(1alpha)) and thromboxane B(2) (TXB2) were assessed. F. hepatica specific IgG and T- and B-lymphocyte ratios were evaluated as indicators of the immune response. Although the applied mode of infection did not result in clinical disease, changes in the plasma eicosanoid pattern were observed. Plasma PGE2 values were significantly elevated in the infected water buffaloes 11 weeks post-infection (w.p.i.). In contrast, transiently but significantly lower TXB2 values than in the uninfected controls were recorded in the phase of chronic fasciolosis. Plasma 6-keto-PGF(1alpha) values were not considerably altered by the infection throughout the study period. F. hepatica-specific IgG were detected from 4 to 21 w.p.i. The proportion of peripheral T- and B-lymphocytes shifted towards B-cells from 2 to 12 w.p.i., gradually returning to control values afterwards. Although the water buffaloes appeared to be rather resistant to trickle infection with F. hepatica, moderate changes in plasma eicosanoid patterns were observed, indicating tissue damage and/or inflammation. Induction of the immune response could be monitored by an increase of F. hepatica-specific IgG, which was paralleled by a relative increase of the B-lymphocyte population.

[Studies on cell transformation and cell cycle in human embryo lungs induced by nickel compounds]

OBJECTIVE

To elucidate the association between nickel compounds and occupational lung cancer.

METHODS

Human embryo lung cells (MRC-9 and IMR-90) were transformed by water-insoluble nickel oxide and nickel subsulfide, and changes in cell cycle of these transformed cells were analyzed by flow cytometric technique.

RESULTS

Morphological transformation in MRC-9 and IMR-90 cells were induced after exposure to nickel compounds for 3 - 5 months, including formation of transforming foci, overlaying growth and epithelium-like changes in cells, etc. Some transformed cells could form colonies in soft agar media. Changes in cell cycle of the transformed cells were observed with flow cytometry. Proportions of cells at G(1) phase and G(2)/M phase were 62.61% and 16.37%, respectively, in the untreated MRC-9 cells and hyperploid cells were hardly seen in cell cycle plots. But, in the transformed MRC-9 cells, proportion of cells at G(1) phase reduced to about 50%, and that at G(2)/M phase increased to over 20% and that of hyperploid cells to over 10%. The same phenomenon was observed in the IMR-90 cells.

CONCLUSIONS

Water-insoluble nickel compounds can induce morphological transformation of human embryo lung cells and those transformed cells appeared certain biological characteristics of tumor cells.

Molecular and cytogenetic analysis of glioblastoma multiforme

Glioblastoma multiforme (GBM) is the most common primary tumor occurring in the central nervous system of adults. Although progress has been made in clinical management of this tumor, little is known about the molecular defects underlying the initiation and progression of GBM. To address these issues, we have characterized five cases of GBM using cytogenetics, comparative genomic hybridization (CGH), fluorescence in situ hybridization (FISH), and direct sequencing. All of these tumors were observed to have clonal chromosome aberrations. Complicated chromosome translocations including der(18)t(2;4;12;18), der(X)t(X;10)(q27.1;p12.1) and der(10)t(10;15)(p11.23;q11.2), and der(1) (:1p31-->1q44::7q11. 3-->7qter) were seen in three tumors. Loss of the CDKN2 gene was noted in four tumors. A gain of copy number of the Cathepsin L gene was seen in two tumors. Amplification of the CDK4, MDM2, and GLI/CHOP genes was noted in two tumors, and amplification of the PDGFR gene was detected in one tumor. Mutation of exon 5 of the TP53 gene was found in three tumors. No mutation of the BCL10 gene was detected in five cases of GBM analyzed, although deletion of chromosome 1p was seen in two tumors. These results provide information for further investigation of GBM.

Structure-function analysis of yeast mRNA cap methyltransferase and high-copy suppression of conditional mutants by AdoMet synthase and the ubiquitin conjugating enzyme Cdc34p

Here we present a genetic analysis of the yeast cap-methylating enzyme Abd1p. To identify individual amino acids required for Abd1p function, we introduced alanine mutations at 35 positions of the 436-amino acid yeast protein. Two new recessive lethal mutations, F256A and Y330A, were identified. Alleles F256L and Y256L were viable, suggesting that hydrophobic residues at these positions sufficed for Abd1p function. Conservative mutations of Asp-178 established that an acidic moiety is essential at this position (i.e. , D178E was viable whereas D178N was not). Phe-256, Tyr-330, and Asp-178 are conserved in all known cellular cap methyltransferases. We isolated temperature-sensitive abd1 alleles and found that abd1-ts cells display a rapid shut-off of protein synthesis upon shift to the restrictive temperature, without wholesale reduction in steady-state mRNA levels. These in vivo results are consistent with classical biochemical studies showing a requirement for the cap methyl group in cap-dependent translation. We explored the issue of how cap methylation might be regulated in vivo by conducting a genetic screen for high-copy suppressors of the ts growth defect of abd1 mutants. The identification of the yeast genes SAM2 and SAM1, which encode AdoMet synthase, as abd1 suppressors suggests that Abd1p function can be modulated by changes in the concentration of its substrate AdoMet. We also identified the ubiquitin conjugating enzyme Cdc34p as a high-copy abd1 suppressor. We show that mutations of Cdc34p that affect its ubiquitin conjugation activity or its capacity to interact with the E3-SCF complex abrogate its abd1 suppressor function. Moreover, the growth defect of abd1 mutants is exacerbated by cdc34-2. These findings suggest a novel role for Cdc34p in gene expression and engender a model whereby cap methylation or cap utilization is negatively regulated by a factor that is degraded when Cdc34p is overexpressed.

Molecular and cytogenetic analysis of lymphoblastoid and colon cancer cell lines from cotton-top tamarin (Sagiunus oedipus)

The cotton-top tamarin (CTT) (Sagiunus oedipus) has been used as an animal model to investigate the etiology and pathophysiology of several human diseases, including ulcerative colitis and its associated colorectal carcinoma (CRC). Little is known, however, about genetic synteny between CTT and humans, and about chromosome aberrations in CTT CRC. To address these issues, we have analyzed CTT lymphoblastoid and CRC cell lines using cytogenetics, fluorescence in situ hybridization (Zoo-FISH), and direct sequencing. The CTT lymphocytes had pseudodiploid chromosomes of 46. The CTT CRC cells showed near-diploid chromosomes of 45. Several clonal structural aberrations were observed, including der(1), a marker chromosome, and double minutes. Zoo-FISH using human chromosome 2, 3, 5, 6, 9, 11, 13, 15, 16, 17, 19, 22, and X paints identified homologous chromosomes and subchromosomal regions in the CTT genome. Fluorescence in situ hybridization with human telomeric probe also detected a homologous sequence in CTT genome. Direct sequencing of CTT genomic DNA using primers amplifying exons 4 and 15 of the human APC gene identified DNA sequences in CTT genome with 99% and 95% homology, respectively. These results provide a basis for further comparative studies of CTT and human genome.

Cdc42 is required for PIP(2)-induced actin polymerization and early development but not for cell viability

BACKGROUND

Cdc42 and other Rho GTPases are conserved from yeast to humans and are thought to regulate multiple cellular functions by inducing coordinated changes in actin reorganization and by activating signaling pathways leading to specific gene expression. Direct evidence implicating upstream signals and components that regulate Cdc42 activity or for required roles of Cdc42 in activation of downstream protein kinase signaling cascades is minimal, however. Also, whereas genetic analyses have shown that Cdc42 is essential for cell viability in yeast, its potential roles in the growth and development of mammalian cells have not been directly assessed.

RESULTS

To elucidate potential functions of Cdc42 mammalian cells, we used gene-targeted mutation to inactivate Cdc42 in mouse embryonic stem (ES) cells and in the mouse germline. Surprisingly, Cdc42-deficient ES cells exhibited normal proliferation and phosphorylation of mitogen- and stress-activated protein kinases. Yet Cdc42 deficiency caused very early embryonic lethality in mice and led to aberrant actin cytoskeletal organization in ES cells. Moreover, extracts from Cdc42-deficient cells failed to support phosphatidylinositol 4,5-bisphosphate (PIP(2))-induced actin polymerization.

CONCLUSIONS

Our studies clearly demonstrate that Cdc42 mediates PIP(2)-induced actin assembly, and document a critical and unique role for Cdc42 in this process. Moreover, we conclude that, unexpectedly, Cdc42 is not necessary for viability or proliferation of mammalian early embryonic cells. Cdc42 is, however, absolutely required for early mammalian development.

[Laboratory diagnosis of Chlamydia trachomatis and Ureaplasma urealyticum of chronic prostatitis]

Prostatic fluid taken from 1038 cases of chronic prostatitis were detected by fluorescent monoclonal antibody technique and isolating cultural method for Chlamydia Trachomatis (CT) and Ureaplasma Urealyticum (UU). The control group consisted of 80 cases. CT and UU were not found in control group. The positive rates of CT and UU infection were 28.4% and 33.0% respectively in the tested group whose cases were abacterial prostatitis. The results suggested that CT and UU are pathogens causing chronic abacterial prostatitis.

[Expression, purification and characterization of fruA, a transcription factor in Myxococcus xanthus]

FruA is a transcription factor essential for the development of Myxocoxccus xanthus. Gene encoding fruA with a poly-histidine tag was expressed in E. coli and simply purified by chromatography on nickel column. Data from gel retardation assay suggest that FruA regulates transcription of target genes in collaboration with other factors.

Expression of the RNA-binding protein TIAR is increased in neurons after ischemic cerebral injury

T-cell restricted intracellular antigen-related protein (TIAR) is an RNA recognition motif-type RNA-binding protein that has been implicated in the apoptotic death of T-lymphocytes and retinal pigment epithelial cells. Western blots prepared with a monoclonal antibody against TIAR showed expression in normal rat hippocampus, and induction by 15 min of global cerebral ischemia. This increased expression was evident at 8 hr after ischemia and maximal at 24 hr, whereas expression at 72 hr was reduced below basal levels. Expression of TIAR protein was also increased in parietal cortex 6 and 24 hr after 90 min of focal cerebral ischemia induced by middle cerebral artery (MCA) occlusion, as well as in cultured cortical neurons and astroglia after exposure to hypoxia in vitro. Immunocytochemistry showed that increased expression of TIAR occurred mainly in the CA1 sector of hippocampus 24 hr after global ischemia, and in cortical and striatal neurons 24 hr after 20 or 90 min of focal ischemia. Double-labeling studies showed that TIAR protein expression was co-localized with DNA damage in neuronal cells. The findings suggest that TIAR may be involved in neuronal cell death after cerebral ischemic injury.