Genetic instability in intestinal metaplasia is a frequent event leading to well-differentiated early adenocarcinoma of the stomach

To understand the development of well-differentiated adenocarcinoma in the stomach, we examined genetic instability in 31 patients with stage Ia gastric cancer. Triplets of tissue specimens (normal/metaplasia/tumour) from 33 lesions were examined for microsatellite instability (MSI) and loss of heterozygosity (LOH), using nine microsatellite loci. Frameshift mutations in the transforming growth factor beta receptor type II (TGF-betaRII) (A)(10), Bcl-2-associated X protein (BAX) (G)(8), hMSH3 (A)(8) and hMSH6 (C)(8) genes were also studied. In this study, a high incidence of MSI (MSI-H) was defined as samples containing 30% or more MSI positive loci, and a low incidence of MSI (MSI-L) as samples which had less than 30% MSI. MSI-L was observed in 19 cancerous lesions (58%), and MSI-H in three (9%). Eleven intestinal metaplasia lesions (33%) showed MSI-L, but no metaplasia lesions exhibited MSI-H. Frameshift mutation was observed in only one cancerous lesion (3%) at the (A)(10) tract of TGF-betaRII. In contrast, LOH was observed in 24 cancerous lesions (73%), and in 15 (45%) of intestinal metaplasia lesions. Intriguingly, these alterations tend to be coincident between metaplasia and cancerous lesions in the same sets of specimens, and there was no case that showed alterations in metaplasia, but not in cancerous lesions. These findings suggest that metaplasia and well-differentiated adenocarcinoma in the stomach may have the same molecular backgrounds, and that these two lesions may be chronologically connected.

Synergistic effect of Bcl-2 and BAG-1 on the prevention of photoreceptor cell death

PURPOSE

Ectopic expression of Bcl-2 in photoreceptors of mice with retinal degenerative disease slows progression of the disease. BAG-1 has previously been shown to augment the inhibitory effect of Bcl-2 on programmed cell death in cultured cell systems. This study was designed to determine whether the coexpression of BAG-1 and Bcl-2 in the photoreceptors of mice with an autosomal dominant form of retinitis pigmentosa (RP) would enhance the protective effect provided by Bcl-2 alone.

METHODS

An expression vector using the 5' regulatory region of the murine opsin gene was used to target the expression of BAG-1 specifically to photoreceptor cells of mice. The BAG-1 transgenic mice were crossed to Bcl-2 transgenics to obtain animals that coexpress the two transgenes in photoreceptor cells. BAG-1/Bcl-2 animals were then crossed to an RP mouse model (a transgenic line overexpressing the S334ter rhodopsin mutant) to assess the effect of coexpression of BAG-1 and Bcl-2 on retinal degeneration. Morphologic analysis was performed on retinas isolated at various times after birth to monitor disease progression.

RESULTS

High levels of BAG-1 expression resulted in retinal degeneration that was not prevented by Bcl-2 expression. However, coexpression of appropriate levels of BAG-1 and Bcl-2 was found to have a profound inhibitory effect on retinal degeneration caused by overexpression of a mutant rhodopsin transgene. Whereas expression of Bcl-2 alone was previously found to delay degeneration of the retina from 2 weeks to approximately 4 weeks of age, coexpression of BAG-1 and Bcl-2 inhibited photoreceptor cell death for as long as 7 to 9 weeks.

CONCLUSIONS

The synergistic effect against photoreceptor cell death produced by the coexpression of Bcl-2 and BAG-1 indicates that these proteins can function in concert to prevent cell death. At the correct dosage, coexpression of Bcl-2 and BAG-1 may serve as a potential means to treat retinal degenerative diseases.

Highly divergent sequences of the pollen self-incompatibility (S) gene in class-I S haplotypes of Brassica campestris (syn. rapa) L

Self-incompatibility (SI) enables flowering plants to discriminate between self- and non-self-pollen. In Brassica, SI is controlled by the highly polymorphic S locus. The recently identified male determinant, termed SP11 or SCR, is thought to be the ligand of S receptor kinase, the female determinant. To examine functional and evolutionary properties of SP11, we cloned 14 alleles from class-I S haplotypes of Brassica campestris and carried out sequence analyses. The sequences of mature SP11 proteins are highly divergent, except for the presence of conserved cysteines. The phylogenetic trees suggest possible co-evolution of the genes encoding the male and female determinants.

Alteration of the self-incompatibility phenotype in Brassica by transformation of the antisense SLG gene

Self-incompatible (SI) Brassica rapa (syn. B. campestris) was transformed with an antisense SLG gene by using SLG8 cDNA isolated from the B. campestris S8 homozygote. Two transformed lines were obtained and analyzed. Northern blot and Western blot analyses revealed that endogenous SLG and SRK were greatly reduced of the transcriptional and translational levels in the transformant. Pollination experiments confirmed that their SI phenotype had broken down. In addition, the progeny with the antisense SLG gene, resulting from self- or cross-pollination of the transgenic plant, also showed the self-compatible phenotype. The breakdown of SI in the tranformants was due to the change in property of the stigma and not of the pollen. These results provide strong evidence that SLG and/or SRK is implicated in the pollen-stigma recognition of SI and that they act only as stigmatic factors.

Isolation and characterization of pollen coat proteins of Brassica campestris that interact with S locus-related glycoprotein 1 involved in pollen-stigma adhesion

Adhesion of pollen grains to the stigmatic surface is a critical step during sexual reproduction in plants. In Brassica, S locus-related glycoprotein 1 (SLR1), a stigma-specific protein belonging to the S gene family of proteins, has been shown to be involved in this step. However, the identity of the interacting counterpart in pollen and the molecular mechanism of this interaction have not been determined. Using an optical biosensor immobilized with S gene family proteins, we detected strong SLR1-binding activity in pollen coat extracts of Brassica campestris. Two SLR1-binding proteins, named SLR1-BP1 and SLR1-BP2, were identified and purified by the combination of SLR1 affinity column chromatography and reverse-phase HPLC. Sequence analyses revealed that these two proteins (i) differ only in that a proline residue near the N terminus is hydroxylated in SLR1-BP1 but not in SLR1-BP2, and (ii) are members of the class A pollen coat protein (PCP) family, which includes PCP-A1, an SLG (S locus glycoprotein)-binding protein isolated from Brassica oleracea. Kinetic analysis showed that SLR1-BP1 and SLR1-BP2 specifically bound SLR1 with high affinity (K(d) = 5.6 and 4.4 nM, respectively). The SLR1-BP gene was specifically expressed in pollen at late stages of development, and its sequence is highly conserved in Brassica species with the A genome.

Effects of medical treatment on gastric mucosal abnormalities in gastroduodenal ulcer disease

The development of carcinoma in cases of gastric ulcer disease during long-term H(2)-blocker treatment is slowly increasing, and ulcers that require such treatment exhibit the characteristics of intractable conditions, including linear ulcers, simultaneous gastric and duodenal ulcers, immature intestinal metaplasia of the gastric epithelium, and atrophic gastritis accompanied with multiple ulcer cicatrices. The incomplete form of intestinal metaplasia resembling Filipe's type III lesions and showing structural atypia developed in the background gastric mucosa in such cases, and the characteristics of this metaplasia included structural atypia, a residuum of gastric-type mucous cells, rapid proliferative activity, and in some areas abnormal expression of P53 protein. In addition, in rat studies it was demonstrated that prolonged administration of H(2)-blockers while gastric ulcers were present accelerated cell proliferation in the background gastric mucosa in the long term. Accordingly, it was considered possible that the development of the incomplete form of intestinal metaplasia, which was strongly suggested to have some relation to the sites where intestinal-type gastric carcinoma appeared, was accelerated by mucosal injury due to chronic ulcers and by persistent elevation in intragastric pH. The results of the present study of gastric carcinoma as a complication of peptic ulcer disease indicated the possibility that Helicobacter pylori was a major contributory factor to the development of the incomplete form of intestinal metaplasia from damage to the background mucosa, but it was unclear whether H. pylori made any direct contribution to carcinogenesis.

An application of apo(a) isoforms for the clinical assessment of Lp(a)

To examine whether or not Lp(a) is applicable as a diagnostic marker for atherosclerosis, we studied the correlation between Lp(a) levels and molecular weights of apo(a) isoforms in sera from both normal healthy adults and diabetic patients. Serum Lp(a) level was measured by turbidimetric immunoassay (TIA) and the molecular weight of apo(a) isoform was determined by Western blotting analysis. The serum Lp(a) levels of the diabetic patients (25.0 mg/dl +/- 2.2 [mean +/- SE], n = 54) were significantly higher than those of the normal subjects (14.4 mg/dl +/- 0.57, n = 500). With respect to the correlation between serum Lp(a) levels and the molecular weights of apo(a) isoforms, there was an inverse correlation in sera from normal subjects (n = 298), whereas there was no correlation in sera from the diabetic patients. Statistical significant inverse correlation (r = -0.91, y = 224.25 - 3.07x) was especially observed in 50 representative apo(a) isotypes from the normal subjects. By applying a standardized curve based on the significant inverse correlation to serum Lp(a) levels, 40.7% (22/54) of the diabetic patients were revealed to have an abnormally high value of serum Lp(a). Moreover, it was found that the significantly higher mean value of serum Lp(a) in the diabetic group was caused by the 22 patients with higher value of Lp(a). The present findings suggest that determination of apo(a) isoform size provides estimation of the serum Lp(a) value and that the inverse correlation curve between serum Lp(a) level and the molecular weight of apo(a) isoform may be applicable to the clinical use of Lp(a).

The pollen determinant of self-incompatibility in Brassica campestris

Many flowering plants possess self-incompatibility (SI) systems that prevent inbreeding. In Brassica, SI is controlled by a single polymorphic locus, the S locus. Two highly polymorphic S locus genes, SLG (S locus glycoprotein) and SRK (S receptor kinase), have been identified, both of which are expressed predominantly in the stigmatic papillar cell. We have shown recently that SRK is the determinant of the S haplotype specificity of the stigma. SRK is thought to serve as a receptor for a pollen ligand, which presumably is encoded by another polymorphic gene at the S locus. We previously have identified an S locus gene, SP11 (S locus protein 11), of the S(9) haplotype of Brassica campestris and proposed that it potentially encodes the pollen ligand. SP11 is a novel member of the PCP (pollen coat protein) family of proteins, some members of which have been shown to interact with SLG. In this work, we identified the SP11 gene from three additional S haplotypes and further characterized the gene. We found that (i) SP11 showed an S haplotype-specific sequence polymorphism; (ii) SP11 was located in the immediate flanking region of the SRK gene of the four S haplotypes examined; (iii) SP11 was expressed in the tapetum of the anther, a site consistent with sporophytic control of Brassica SI; and (iv) recombinant SP11 of the S(9) haplotype applied to papillar cells of S(9) stigmas, but not of S(8) stigmas, elicited SI response, resulting in inhibition of hydration of cross-pollen. All these results taken together strongly suggest that SP11 is the pollen S determinant in SI.

Long-term toxicity and carcinogenicity study of cyclamate in nonhuman primates

Twenty-one monkeys (cynomolgus, rhesus, African green) were fed cyclamate (100 mg/kg and 500 mg/kg) in the diet five times per week from a few days after birth and continuing for up to 24 years. Malignant tumors were diagnosed in three 24-year-old cyclamate monkeys; these were metastatic colon carcinoma (rhesus; 500 mg/kg), metastatic hepatocellular carcinoma (cynomolgus; 500 mg/kg), and a small, well differentiated adenocarcinoma of the prostate (cynomolgus; 100 mg/kg). Benign tumors were found at necropsy in three females; these were adenoma of the thyroid gland (rhesus; 100 mg/kg) and two cases of leiomyoma of the uterus (rhesus; 100 mg/kg and 500 mg/kg). No tumors were detected in an age-matched control group of 16 monkeys. Examination of the testes revealed complete testicular atrophy in one of the old cyclamate monkeys, and focal germ cell aplasia (Sertoli-only tubules) in two other cyclamate monkeys. Focal spermatogenic interruption (maturation arrest) at various germ cell levels mixed with normal spermatogenesis was observed in both the cyclamate-treated and the control monkeys, all of which were over 20 years old. Measurements of terminal cyclohexylamine concentrations showed that three of the males dosed with cyclamate at 500 mg/kg were high converters, with plasma concentrations comparable to the levels that produce testicular atrophy in rats. However, only one of the three high converters showed histologic evidence of irregular spermatogenesis. The overall conclusion is that the testicular abnormalities and the sporadic cases of different malignancies found after more than 20 years of dosing do not provide clear evidence of a toxic or carcinogenic effect of sodium cyclamate in monkeys.

Patterning proteins and cells using soft lithography

This review describes the pattering of proteins and cells using a non-photolithographic microfabrication technology, which we call 'soft lithography' because it consists of a set of related techniques, each of which uses stamps or channels fabricated in an elastomeric ('soft') material for pattern transfer. The review covers three soft lithographic techniques: microcontact printing, patterning using microfluidic channels, and laminar flow patterning. These soft lithographic techniques are inexpensive, are procedurally simple, and can be used to pattern a variety of planar and non-planar substrates. Their successful application does not require stringent regulation of the laboratory environment, and they can be used to pattern surfaces with delicate ligands. They provide control over both the surface chemistry and the cellular environment. We discuss both the procedures for patterning based on these soft lithographic techniques, and their applications in biosensor technology, in tissue engineering, and for fundamental studies in cell biology.

Differential effects of the hsp70-binding protein BAG-1 on glucocorticoid receptor folding by the hsp90-based chaperone machinery

The heat shock protein hsp70/hsc70 is a required component of a five-protein (hsp90, hsp70, Hop, hsp40, and p23) minimal chaperone system reconstituted from reticulocyte lysate that forms glucocorticoid receptor (GR).hsp90 heterocomplexes. BAG-1 is a cofactor that binds to the ATPase domain of hsp70/hsc70 and that modulates its chaperone activity. Inasmuch as BAG-1 has been found in association with several members of the steroid receptor family, we have examined the effect of BAG-1 on GR folding and GR.hsp90 heterocomplex assembly. BAG-1 was present in reticulocyte lysate at a BAG-1:hsp70/hsc70 molar ratio of approximately 0.03, and its elimination by immunoadsorption did not affect GR folding and GR. hsp90 heterocomplex assembly. At low BAG-1:hsp70/hsc70 ratios, BAG-1 promoted the release of Hop from the hsp90-based chaperone system without inhibiting GR.hsp90 heterocomplex assembly. However, at molar ratios approaching stoichiometry with hsp70, BAG-1 produced a concentration-dependent inhibition of GR folding to the steroid-binding form with corresponding inhibition of GR.hsp90 heterocomplex assembly by the minimal five-protein chaperone system. Also, there was decreased steroid-binding activity in cells that were transiently or stably transfected with BAG-1. These observations suggest that, at physiological concentrations, BAG-1 modulates assembly by promoting Hop release from the assembly complex; but, at concentrations closer to those in transfected cells and some transformed cell lines, hsp70 is continuously bound by BAG-1, and heterocomplex assembly is blocked.

Relationship between polyploidy and pollen self-incompatibility phenotype in Petunia hybrida Vilm

Self-incompatibility in Solanaceae is controlled by a single multiallelic locus, the S-locus. The S-allele associated ribonucleases (S-RNases) in the pistil are involved in pollen rejection. In this work, we analyzed two newly isolated lines of Petunia hybrida, termed PB and PF. They both had the same set of S-RNases (SB1- and SB2-RNases), however the PB was a self-incompatible diploid while PF was a self-compatible tetraploid. Cross pollination tests between PB and PF indicated diploid pollen from PF lost the incompatibility phenotype. In order to clarify the effects of polyploidy on pollen phenotypic change, we artificially induced tetraploid plants from a diploid SB1SB2 heterozygote (= PB) and a diploid SB1SB1 homozygote. The obtained SB1 SB1SB1SB1 homoallelic tetraploid remained self-incompatible, whereas the SB1SB1SB2SB2 heteroallelic tetraploid became self-compatible. These data suggested that the diploid heteroallelic pollen lost the incompatibility phenotype and had the characteristics of self-compatibility with SB1SB2 style.

Regeneration of periodontal tissues by basic fibroblast growth factor

Several growth factors (or cytokines) have recently received attention because of their ability to actively regulate various cellular functions of periodontal ligament (PDL) cells and the effects of topical application of such factor(s) on periodontal tissue regeneration has been evaluated. In this study, we examined the role of basic fibroblast growth factor (bFGF) in the wound healing and regeneration of periodontal tissues. Alveolar bone defects (such as 2-wall, 3-wall and furcation class II bone defects) were created surgically in beagle dogs and primates. Recombinant bFGF was topically applied to the artificial bony defects. Six or 8 wk after application, the periodontal regeneration was morphologically and histomorphometrically analyzed. In all sites where bFGF was applied, significant periodontal ligament formation with new cementum deposits and new bone formation was observed in amounts greater than in the control sites. We found it noteworthy that no instances of epithelial down growth, ankylosis or root resorption were observed in the bFGF sites. In vitro studies demonstrated that bFGF enhances the proliferative responses of human PDL cells, which express FGF receptor-1 and -2, but inhibits the induction of alkaline phosphatase activity and mineralized nodule formation by PDL cells. Interestingly, we observed that the mRNA level of laminin in PDL cells, which plays an important role in angiogenesis, was specifically upregulated by bFGF stimulation, but that of type I collagen was downregulated. The present study demonstrates that bFGF can be applied as one of the therapeutic modalities which actively induce periodontal tissue regeneration. The results of in vitro studies suggest that by suppressing the cytodifferentiation of PDL cells into mineralized tissue forming cells, bFGF may play important roles in wound healing by promoting angiogenesis and inducing the growth of immature PDL cells, and may in turn accelerate periodontal regeneration.

Oxidation of Benzyl Alcohol with Cu(II) and Zn(II) Complexes of the Phenoxyl Radical as a Model of the Reaction of Galactose Oxidase

Profound insights into the catalytic mechanism of galactose oxidase (GO) are offered by new models of the active form of the metalloenzyme. The important role of the Cu(II) center in the oxidation of benzyl alcohol to benzaldehyde by the Cu(II)-phenoxyl radical complex of ligand 1 has been revealed by comparison with the reactivity of the corresponding Zn(II)-phenoxyl radical complex; py=2-pyridyl.

Genomic organization of the S locus: Identification and characterization of genes in SLG/SRK region of S(9) haplotype of Brassica campestris (syn. rapa)

In Brassica, two self-incompatibility genes, encoding SLG (S locus glycoprotein) and SRK (S-receptor kinase), are located at the S locus and expressed in the stigma. Recent molecular analysis has revealed that the S locus is highly polymorphic and contains several genes, i.e., SLG, SRK, the as-yet-unidentified pollen S gene(s), and other linked genes. In the present study, we searched for expressed sequences in a 76-kb SLG/SRK region of the S(9) haplotype of Brassica campestris (syn. rapa) and identified 10 genes in addition to the four previously identified (SLG(9), SRK(9), SAE1, and SLL2) in this haplotype. This gene density (1 gene/5.4 kb) suggests that the S locus is embedded in a gene-rich region of the genome. The average G + C content in this region is 32.6%. An En/Spm-type transposon-like element was found downstream of SLG(9). Among the genes we identified that had not previously been found to be linked to the S locus were genes encoding a small cysteine-rich protein, a J-domain protein, and an antisilencing protein (ASF1) homologue. The small cysteine-rich protein was similar to a pollen coat protein, named PCP-A1, which had previously been shown to bind SLG.

In vivo antiviral effect of interleukin 18 in a mouse model of vaccinia virus infection

Interleukin-18 (IL-18), originally called interferon-gamma (IFN-gamma)-inducing factor is a novel cytokine which exhibits pleiotropic immunomodulatory activities such as the activation of natural killer (NK) cells and cytotoxic T lymphocytes (CTL). In this study, the efficacy of IL-18 on viral infection in mice was investigated. IL-18 treatment significantly suppressed pock formation on the tails of BALB/c mice inoculated intravenously with vaccinia virus when the cytokine was administered intraperitoneally on days 0, 2 and 4 after infection. Sequentially, NK and CTL activity of the infected mice were significantly augmented by IL-18 injection. The in vivo anti-vaccinia virus activity of IL-18 was only partially inhibited by treating the infected mice with anti-asialo GM1 antibody. When infected mice were injected with anti-IFN-gamma antibody only, severe deterioration of health and significant body weight loss were observed, suggesting that IFN-gamma is very important in protecting mice against vaccinia virus infection. Interestingly, IL-18 injection visibly improved the severe vaccinia virus-induced symptoms in mice treated with anti-IFN-gamma antibody, even though a pivotal involvement of IFN-gamma in IL-18-mediated anti-vaccinia virus effect is not yet determined. Taken together, these results indicate that the IL-18-elicited anti-vaccinia virus effect in the acute phase of infection would be raised by the sum of various host defence mechanisms including NK cells and CTL, and not from a specific immunocompetent cell population or effector molecule.

Effects of oral administration of interferon-alpha on antibody production in mice with induced tolerance

In vivo systemic effects and the immunomodulating potential of the oral administration of murine interferon-alpha (IFN-alpha) were investigated through mRNA expression of both IFN-alpha-inducible factors, interferon regulatory factor-1 (IRF-1) and 2,5-adenylate synthetase [2-5(A) synthetase] and 2-5(A) synthetase enzymatic activity in spleen and antibody production. The daily administration of IFN-alpha (0.1, 1, 10, and 100 IU/body) for 1 week augmented IRF-1 and 2-5(A) synthetase mRNA expression levels, as well as 2-5(A) synthetase enzymatic activity in spleen cells but not in cervical lymph nodes. The in vivo immunomodulating potential of the oral administration of IFN-alpha was also evaluated through antibody production in mice with induced tolerance. Ovalbumin (OVA) was administered intraperitoneally (i.p.) to induce systemic antibody production on day 0 when OVA feeding was initiated. The OVA was fed every 2-3 days for a total of 14 doses to suppress serum antibody levels. Oral administration of murine IFN-alpha was initiated on day 0 and was continued for 5 consecutive days weekly for 5 weeks (24 doses). On every sampling date (days 10, 17, 24, and 32), specific antibody levels in the IFN-alpha-administered groups were significantly higher than those in the control (nonadministered) group. This was especially noted in early phases (days 10 and 17) of antibody production when the levels of antibody in serum from the IFN-alpha-administration groups were equivalent to those of the nontolerance group. Altogether, it is suggested that oral use of IFN-alpha can elicit immunomodulating actions (e.g., antibody levels) by affecting the systemic immune system(s).

Oral use of interferon-alpha delays the onset of insulin-dependent diabetes mellitus in nonobese diabetes mice

Insulin-dependent diabetes mellitus (IDDM) in the nonobese diabetes (NOD) mouse model is thought to be an autoimmune CD4 Th1-like cell-mediated disease. We tested the efficacy of oral use of interferon-alpha (IFN-alpha) therapy on IDDM in NOD mice. Using urine and blood sugar levels as indicators of IDDM, oral administration of murine IFN-alpha (100 IU/body) to NOD mice significantly delayed the onset of symptomatic diabetes. However, oral use of IFN-alpha did not prevent diabetic NOD mice from losing weight once NOD mice were symptomatic, suggesting that orally administered IFN-alpha is a prophylactic rather than therapeutic approach to the management of IDDM.

Centromeric localization of an S-RNase gene in Petunia hybrida Vilm

S-RNase has been identified to be an S-allele-specific stylar determinant contributing to the self-incompatibility response in Solanaceae. In order to examine the physical location of the S-RNase gene, multi-color fluorescence in situ hybridization (FISH) using the S (B1) -RNase cDNA probe and ribosomal RNA gene (rDNA) probe was performed on an S (B1) S (B2 )heterozygote of Petunia hybrida. The S (B1) -RNase gene was detected as a doublet signal close to the centromere of chromosome III. Next, we performed FISH using a large genome probe prepared from a λSB1-311 clone (20 kb) which contains the S (B1) -RNase gene and its 3´ flanking region. This probe hybridized to the centromeric regions of all P. hybrida chromosomes. Sequence analysis of the λSB1-311 clone revealed the presence of a repetitive sequence consisting of a novel 666 bp unit sequence. A subclone (pBS-SB1B5) containing this unit sequence also hybridized to all of the centromeric regions, confirming that this unit is the centromeric specific repetitive sequence. These data suggested that the S ( B1 ) -RNase gene is located very close to (within a distance of 12 kb from) the centromeric-specific repetitive sequence. Likewise, the pBS-SB1B5 probe hybridized to the centromeric regions of all chromosomes in P. littoralis, another Petunia species. However, the probe did not hybridize to the centromere of the chromosomes from other species in Solanaceae. These results suggested that this centromeric repetitive sequence might be a genus-specific one.

The value of serial auditory brainstem response in patients with subacute sclerosing panencephalitis

A total of 98 serial auditory brainstem responses from 17 patients (11 boys and 6 girls) with subacute sclerosing panencephalitis were compared with their clinical course and stages. These patients were exposed to measles early in life (at 1.8 +/- 1.4 years old) with the average onset of the disease at 8.8 +/- 0.7 years of age. The main abnormalities of their auditory brainstem responses were a prolongation of waves I, III, and V, and of the I to V interpeak interval. Wave V thresholds were also elevated. These effects on the auditory brainstem responses started 1 to 2 years after onset of neurologic signs. I to V interpeak latency became prolonged with the progress of clinical stages, especially in Jabbour's clinically advanced stage IV. In two patients with an acute progressive type of subacute sclerosing panencephalitis, very rapid deterioration with a distorted wave pattern of later components was observed. These findings suggest rostrocaudal progression in the central nervous system of both long-term and fulminant cases.

Partial nucleotide sequencing of the NS3/helicase region of hepatitis G virus to prove vertical transmission

To study non-parental transmission of hepatitis G virus and/or GB virus C (HGV/GBV-C), we sequenced and compared the NS3/helicase region of the virus for five HGV/GBV-C RNA-positive mothers and their 11 children who had experienced neither blood transfusion nor overt hepatitis and were negative for HBV, HCV and HIV, except in one mother coinfected with HCV. The nucleotide sequences of the familial HGV/GBV-C isolates showed high similarity of 99-100% (mean 99.8%, 100% at the deduced amino acid level) between mother and her child(ren) in each family. These findings strongly suggest the spontaneous occurrence of mother-to-child transmission of HGV/GBV-C as reported previously. They also suggest that nucleotide sequence analysis on the NS3/helicase region of HGV/GBV-C may be a useful tool to study HGV/GBV-C transmission.

BAG-1 accelerates cell motility of human gastric cancer cells

BAG-1 is a Hsp70/Hsc70-binding protein that interacts with Bcl-2, Raf-1, steroid hormone receptors, Siah-1, and hepatocyte growth factor (HGF) receptors, implying multiple functions for the BAG-1 protein. Here, we provide evidence that gene transfer-mediated overexpression of BAG-1 markedly enhances the motility of human gastric cancer cells. Two independent in vitro migration assays showed that the BAG-1-expressing MKN74 cells exhibited more active migration compared with control transfectants or parent MKN74 cells. In MKN74 cells, the overexpression of BAG-1 affected neither cell adhesion capability nor migration responses to HGF. The promotive effect of BAG-1 on cell migration was similarly observed in transfectants of another human gastric cancer MKN45 cell line. In BAG-1 transfected gastric cancer MKN74 cells, BAG-1 colocalized with cytokeratin as well as actin filaments, and was concentrated at membrane ruffles induced by lysophosphatidic acid (LPA). Taken together, these studies demonstrate that BAG-1 has a novel function as promoter of cell migration in human gastric cancer cells, possibly through cooperation with cytoskeletal proteins.

Effects of long-term oral administration of DDT on nonhuman primates

Because of reports on tumorigenic activity in different animal species exposed to DDT a decision was made in 1969 to evaluate the long-term effects of DDT on 24 cynomolgus and rhesus monkeys. DDT (20 mg/kg) was given in the diet for 130 months, followed by an observation period that ended in 1994. The two cases of malignant tumor detected in the DDT group included a metastatic hepatocellular carcinoma in a 233-month-old male and a well-differentiated adenocarcinoma of the prostate in a 212-month-old monkey. Benign tumors detected in the DDT group included three cases of leiomyoma, two of which were uterine and one, esophageal. No tumor was detected in the control group of 17 monkeys. Fatty changes in the liver were observed in 52.9% of the DDT group and 29.4% of the control group. More specific signs of hepatotoxicity were documented microscopically in seven DDT monkeys. Severe tremors and histological evidence of CNS and spinal cord abnormalities were observed in six DDT monkeys. The present findings show clear evidence of hepatic and CNS toxicity following long-term DDT administration to cynomolgus and rhesus monkeys. However, the two cases involving malignant tumors of different types are inconclusive with respect to a carcinogenic effect of DDT in nonhuman primates.

Patterning cells and their environments using multiple laminar fluid flows in capillary networks

This paper describes the use of laminar flow of liquids in capillary systems to pattern the cell culture substrate, to perform patterned cell deposition, and to pattern the cell culture media. We demonstrate the patterning of the cell culture substrate with different proteins, the patterning of different types of cells adjacent to each other, the patterned delivery of chemicals to adhered cells, and performing enzymatic reactions over select cells or over a portion of a cell. This method offers a way to simultaneously control the characteristics of the surface to which cells are attached, the type of cells that are in their vicinity, and the kind of media that cells or part of a cell are exposed to. The method is experimentally simple, highly adaptable, and requires no special equipment except for an elastomeric relief that can be readily prepared by rapid prototyping.

Usefulness of dual SPECT with Tc-99m pyrophosphate and Tl-201 to predict further events after acute myocardial infarction with single-vessel coronary artery disease

PURPOSE

This study was undertaken to determine whether the findings of dual SPECT with Tc-99m pyrophosphate (PYP) and Tl-201 were predictive of further cardiac events after acute myocardial infarction.

METHODS

The authors evaluated 88 patients with acute myocardial infarction who underwent dual SPECT for single-vessel coronary artery disease.

RESULTS

Twenty-nine patients showed overlapping of Tc-99m PYP and Tl-201 in the same location (overlap-positive group), and 59 patients had no overlap (overlap-negative group). In patients in the overlap-positive group, the incidence of subsequent events was significantly higher than in patients in the overlap-negative group (P < 0.001). In the overlap-positive group, the number of overlap segments in patients with further events was significantly greater than that in patients without further events (P < 0.005).

CONCLUSIONS

Areas with overlapping of Tc-99m PYP and Tl-201 may contain jeopardized myocardium. These results suggest that patients who have a Tc-99m PYP and Tl-201 overlap-negative scan are a low risk group, whereas patients who have more overlapping segments may require catheterization and revascularization. Thus simultaneous SPECT imaging with Tc-99m PYP and Tl-201 might be useful to identify patients with greater ischemic risk after acute myocardial infarction.

Multiple infection of TT virus (TTV) with different genotypes in Japanese hemophiliacs

To clarify the persistent TT virus (TTV) infection, we studied a possibility of multiple TTV infection by genotype analysis of isolated TTV obtained from seven Japanese hemophiliacs. The nucleotide sequences including 222 bp in the open reading frame 1 (ORF1) region of 10 TTV isolates from each patient were analyzed and classified into various TTV genotypes such as G1 to G6 by phylogenetic analysis using a N-J method. Multiple TTV genotypes were observed in all the hemophiliacs: three different TTV genotypes were found in three patients, whereas four different TTV genotypes were observed in the other three patients. The remaining patient was also infected with TTV of five different genotypes. Moreover, new TTV genotypes were found in these seven patients and tentatively designated as G7. The present findings indicate that multiple TTV infection with different TTV genotypes has occurred in Japanese hemophiliacs. They also provide valuable information to understand persistent TTV infection.

Prevalence and persistence of a novel DNA TT virus (TTV) infection in Japanese haemophiliacs

To clarify the clinical implication of a newly discovered 'TT virus (TTV)', we assayed TTV DNA in sera from 50 haemophiliacs by a seminested-PCR. TTV DNA was detected in 75% (35/50), which was a much higher prevalence than for HBV (HBc-Ab), HCV RNA, or HGV RNA. In particular, TTV DNA was found in 44.4% (4/8) of patients who had been treated only with virally inactivated factor VIII concentrates. Elevated ALT levels were observed in patients with HCV RNA and TTV DNA; however, the elevation in TTV DNA was obtained from patients co-infected with HCV RNA (62.9%, 22/35). There was no significant difference in ALT levels between TTV DNA-positive and DNA-negative in patients without HCV RNA. 85.3% (35/41) of TTV DNA-positive sera in 1990 were again positive for TTV DNA in 1995. These findings suggest that many haemophiliacs have been infected with TTV. Although TTV infection was not associated with serum ALT elevation, persistent TTV infection may contribute to cryptogenic hepatic failure in haemophiliacs.

Prognostic significance of apoptosis regulators in breast cancer

Dysregulation of normal programmed cell death mechanisms plays an important role in the pathogenesis and progression of breast cancer, as well as in responses of tumors to therapeutic intervention. Overexpression of anti-apoptotic members of the Bcl-2 family such as Bcl-2 and Bcl-X(L) has been implicated in cancer chemoresistance, whereas high levels of pro-apoptotic proteins such as Bax promote apoptosis and sensitize tumor cells to various anticancer therapies. Though the mechanisms by which Bcl-2 family proteins regulate apoptosis are diverse, ultimately they govern decision steps that determine whether certain caspase family cell death proteases remain quiescent or become active. To date, approximately 17 cellular homologs of Bcl-2 and at least 15 caspases have been identified in mammals. Other types of proteins may also modulate apoptotic responses through effects on apoptosis-regulatory proteins, such as BAG-1-a heat shock protein 70 kDa (Hsp70/Hsc70)-binding protein that can modulate stress responses and alter the functions of a variety of proteins involved in cell death and division. In this report, we summarize our attempts thus far to explore the expression of several Bcl-2 family proteins, caspase-3, and BAG-1 in primary breast cancer specimens and breast cancer cell lines. Moreover, we describe some of our preliminary observations concerning the prognostic significance of these apoptosis regulatory proteins in breast cancer patients, contrasting results derived from women with localized disease (with or without node involvement) and metastatic cancer.

Selective inhibition of beta-1,4- and alpha-1,3-galactosyltransferases: donor sugar-nucleotide based approach

A combined rational and library approach was used to identify bisphosphonates (IC50 = 20 microM) and galactose type 1-N-iminosugar (IC50=45 microM) as novel motifs for selective inhibition of beta-1,4-galactosyltransferase (beta-1,4-GalT) and alpha-1,3-galactosyltransferase (alpha-1,3-GalT), respectively. Our results demonstrate that, though these two galactosyltransferases both utilize the same donor sugar-nucleotide (UDP-Gal), the difference in their mechanisms can be utilized to design donor sugar or nucleotide analogues with inhibitory activities selective for only one of the galactosyltransferases. Investigation of beta-1,4-GalT inhibition using UDP-2-deoxy-2-fluorogalactose (UDP-2-F-Gal), UDP, and bisphosphonates, also led to the observation of metal dependent inhibition of beta-1,4-GalT. These observations and the novel inhibitor motifs identified in this study pave the way for the design and identification of even more potent and selective galactosyltransferase inhibitors.

Clinicopathological study of background gastric mucosa during long-term conservative maintenance therapy for intractable peptic ulcer

We studied the background gastric mucosa in eight patients with intractable peptic ulcer in whom gastric cancer developed during more than 4 years' administration of histamine (H)2-receptor antagonists (H2-RAs), and in two patients with intractable gastric ulcer without gastric cancer in whom H2-RAs were administered for 4 years. As controls, we studied background mucosa in seven patients with combined gastroduoderal ulcers not treated with H2-RAs. The cancers were differentiated adenocarcinomas in all eight patients. The characteristic features of these patients and of the two patients with intractable gastric ulcer were: expansion of the generative cell zone, poor differentiation of the goblet cells, mild cellular atypia, and abnormal branching and anastomosis of glands, as well as wide areas of incomplete-type intestinal metaplasia. The sites of the differentiated adenocarcinomas were classified by mucin histochemistry as intestinal-type mucosa in all patients. A special type of incomplete intestinal metaplasia, of the intestinal type and which retained gastric-type properties, was present in some areas, and p53-positive cells were observed in some areas. In patients with intractable gastric ulcer in whom the background gastric mucosa had been exposed to more than 4 years of H2-RA treatment, it was considered possible that the preconditions for cancerous lesions were present.

An evolutionarily conserved family of Hsp70/Hsc70 molecular chaperone regulators

Heat Shock Protein 70 kDa (Hsp70) family molecular chaperones play critical roles in protein folding and trafficking in all eukaryotic cells. The mechanisms by which Hsp70 family chaperones are regulated, however, are only partly understood. BAG-1 binds the ATPase domains of Hsp70 and Hsc70, modulating their chaperone activity and functioning as a competitive antagonist of the co-chaperone Hip. We describe the identification of a family of BAG-1-related proteins from humans (BAG-2, BAG-3, BAG-4, BAG-5), the invertebrate Caenorhabditis elegans (BAG-1, BAG-2), and the fission yeast Schizosaccharomyces pombe (BAG-1A, BAG-1B). These proteins all contain a conserved approximately 45-amino acid region near their C termini (the BAG domain) that binds Hsc70/Hsp70, but they differ widely in their N-terminal domains. The human BAG-1, BAG-2, and BAG-3 proteins bind with high affinity (KD congruent with 1-10 nM) to the ATPase domain of Hsc70 and inhibit its chaperone activity in a Hip-repressible manner. The findings suggest opportunities for specification and diversification of Hsp70/Hsc70 chaperone functions through interactions with various BAG-family proteins.

[Biochemical and immunohistological changes in the gastric mucosa of rats with long-term administration of histamine H2-receptor antagonist]

Effects of long term administration of Histamine H2-receptor Antagonist (H2-RA) in the treatment of peptic ulcer was studied for the influence to the risk of causing precancerous changes in gastric mucosa. Serum gastrin. ODC activities, polyamine and PCNA labeling index were biochemically and immunohistologically observed. Rat's mucosae with experimentally induced peptic ulcer treated with long term H2-RA, showed no morphological changes but at 30 weeks of H2-RA, had significantly higher value in PCNA labeling index and in polyamine (spermidine) quantity compared to control H2-RA alone and ulcer alone groups. These results suggest that long term administration of H2-RA, even after healing of the ulcer, may cause the gastric mucosa to possess a milieu in favour of precancerous changes, due to the increased proliferative activity of the cells.

Chemoenzymatic synthesis of iminocyclitol derivatives: a useful library strategy for the development of selective fucosyltransfer enzymes inhibitors

A chemoenzymatic strategy has been developed for the synthesis of libraries of iminocyclitol derivatives for the discovery of new and selective fucosidase inhibitors.

Acceptor substrate-based selective inhibition of galactosyltransferases

This paper describes the discovery of glycosyl acceptor analogs as potent and selective inhibitors of alpha-1,3- and beta-1,4-galactosyltransferases. Incorporation of an appropriate aromatic group to the aglycon position of the enzyme's acceptors results in a strong inhibition, representing the first and most potent small uncharged molecules as selective inhibitors of these two enzymes and thus providing a new strategy for the development of selective glycosyltransferase inhibitors.

BAG-1, a negative regulator of Hsp70 chaperone activity, uncouples nucleotide hydrolysis from substrate release

Molecular chaperones influence the process of protein folding and, under conditions of stress, recognize non-native proteins to ensure that misfolded proteins neither appear nor accumulate. BAG-1, identified as an Hsp70 associated protein, was shown to have the unique properties of a negative regulator of Hsp70. Here, we demonstrate that BAG-1 inhibits the in vitro protein refolding activity of Hsp70 by forming stable ternary complexes with non-native substrates that do not release even in the presence of nucleotide and the co-chaperone, Hdj-1. However, the substrate in the BAG-1-containing ternary complex does not aggregate and remains in a soluble intermediate folded state, indistinguishable from the refolding-competent substrate-Hsp70 complex. BAG-1 neither inhibits the Hsp70 ATPase, nor has the properties of a nucleotide exchange factor; instead, it stimulates ATPase activity, similar to that observed for Hdj-1, but with opposite consequences. In the presence of BAG-1, the conformation of Hsp70 is altered such that the substrate binding domain becomes less accessible to protease digestion, even in the presence of nucleotide and Hdj-1. These results suggest a mechanistic basis for BAG-1 as a negative regulator of the Hsp70-Hdj-1 chaperone cycle.

Erythrocyte aldose reductase protein: a clue to elucidate risk factors for diabetic neuropathies independent of glycemic control

Prolonged hyperglycemia has been thought to be the primary cause of diabetic complications, however, some diabetic patients develop severe complications early in duration of diabetes, while some patients have no or mild complications even after prolonged hyperglycemia. To investigate the risk factors for diabetic severe neuropathy independent of glycemic control and duration of diabetes, erythrocyte aldose reductase was determined in 43 non-insulin-dependent diabetic patients by a two-site ELISA using recombinant human aldose reductase. Among 20 patients with severe neuropathy which was developed within 5 years of diagnosis, the level of erythrocyte aldose reductase protein was significantly higher than that of 23 patients with no or mild neuropathy who had more than 8 years duration of diabetes and prolonged hyperglycemia (11.9+/-5.7 vs. 8.3+/-1.3 ng/mgHb, P < 0.0001). There was a significant stability of the erythrocyte aldose reductase (AR) in the 40 diabetic patients during 1-4 years. The logistic regression analysis revealed that the maximum body mass index (BMI) in the past minus present BMI and the level of erythrocyte aldose reductase protein were the independent risk factors for diabetic severe neuropathy. The measurement of erythrocyte AR level may be useful for predicting severe neuropathy in non-insulin-dependent diabetes mellitus (NIDDM) patients.

Influence of the anti-allergic agent, azelastine, on tumor necrosis factor-alpha (TNF-alpha) secretion from cultured mouse mast cells

The influence of azelastine (AZ) on tumor necrosis factor-alpha (TNF-alpha) secretllon from cultured mast cells was examined. Mast cells were induced by the long-term culture of mouse (BALB/c, Male) spleen cells with interleukin-3. Mast cells collected on day 20 in culture were stimulated with 2.5 micrograms/ml of concanavalin A (Con A) in the presence of various doses of AZ for 24 hours. AZ scarcely affected TNF-alpha secretion from mast cells when low doses (0.5 and 1.0 microgram/ml) of AZ were added to cultures. However, higher doses (5.0 and 10.0 micrograms/ml) of AZ inhibited the secretion (but not production) of TNF-alpha from mast cells. These results may suggest that some of the therapeutic effects of AZ depend on its ability to reduce the secretion of TNF-alpha from mast cells.

Characterization of interactions between the anti-apoptotic protein BAG-1 and Hsc70 molecular chaperones

The anti-cell death protein BAG-1 binds to 70-kDa heat shock proteins (Hsp70/Hsc70) and modulates their chaperone activity. Among other facilitory roles, BAG-1 may serve as a nucleotide exchange factor for Hsp70/Hsc70 family proteins and thus represents the first example of a eukaryotic homologue of the bacterial co-chaperone GrpE. In this study, the interactions between BAG-1 and Hsc70 are characterized and compared with the analogous GrpE-DnaK bacterial system. In contrast to GrpE, which binds DnaK as a dimer, BAG-1 binds to Hsc70 as a monomer with a 1:1 stoichiometry. Dynamic light scattering, sedimentation equilibrium, and circular dichroism measurements provided evidence that BAG-1 exists as an elongated, highly helical monomer in solution. Isothermal titration microcalorimetry was used to determine the complex stoichiometry and an equilibrium dissociation constant, KD, of 100 nM. Kinetic analysis using surface plasmon resonance yielded a KD consistent with the calorimetrically determined value. Molecular modeling permitted a comparison of structural features between the functionally homologous BAG-1 and GrpE proteins. These data were used to propose a mechanism for BAG-1 in the regulation of Hsp70/Hsc70 chaperone activity.

Dual radionuclide single-photon emission computed tomography in the prediction of further ischemic risk after acute myocardial infarction

To evaluate whether the findings of dual single-photon emission computed tomography (SPECT) with technetium-99m pyrophosphate (Tc-99m PPi) and thallium-201 were predictive of further cardiac events in their hospital course, we studied 130 patients recovering from acute myocardial infarction (AMI). Fifty-four patients showed overlapping of Tc-99m PPi and thallium-201 in the same location (overlap positive group), and 76 patients had no overlap (overlap negative group). Of the 130 patients, 36 (28%) had a cardiac event. In patients in the overlap positive group, the incidence of subsequent events was significantly higher than in patients in the overlap negative group (44% versus 16%; p < 0.001). In the overlap positive group, the Tc-99m PPi uptake score and the number of overlap segments in patients with further events was significantly higher than those in patients without further events (10.2 +/- 5.1 versus 6.4 +/- 4.1, p < 0.005 and 5.2 +/- 2.0 versus 3.3 +/- 1.3, p < 0.001, respectively). These results suggest that patients who have a Tc-99m PPi and thallium-201 overlap negative scan can be candidates for early hospital discharge. In contrast, patients who have a greater number of overlap segments may require early catheterization and revascularization, so that simultaneous SPECT imaging Tc-99m PPi and thallium-201 might be useful for identifying patients with further ischemic risk after AMI in their hospital course.

Expression of receptors for basic fibroblast growth factor on human periodontal ligament cells

Basic fibroblast growth factor (FGF-2; bFGF) is a major mitogen for connective tissue cells, and participates in the healing process. It has already been reported that FGF-2 could be applicable to enhance periodontal regeneration. In the present study, we examined FGF receptor (FGFR) expression on human periodontal ligament (PDL) cells. The binding of [125I]-labeled FGF-2 to human PDL cells was studied by radioreceptor assay. The binding of [125I]-FGF-2 to PDL cells reached a plateau after 2.5 h incubation at 4 degrees C and was inhibited by the addition of unlabeled FGF-2 and acidic FGF (FGF-1; aFGF), but not insulin-like growth factor-I, platelet-derived growth factor and transforming growth factor-beta 1. Scatchard analysis revealed the presence of approximately 1.0 x 10(5) FGF-2 binding sites per cell with an apparent Kd of 1.2 x 10(-10) M. Interestingly, the binding of [125I]-FGF-2 on PDL cells reached its maximum at d 6 of the culture and then gradually decreased. Scatchard analysis also demonstrated that the number of FGFRs on a PDL cell was altered during the course of the culture, while the affinity between FGF-2 and its receptor was not. The responsiveness of PDL cells to FGF-2, which was monitored by the inhibitory effect on alkaline phosphatase activity, was reduced in proportion to the decrease in the number of FGFRs on the PDL cells. The present study suggests that PDL cells alter the responsiveness to FGF-2 during the course of the culture by changing the density of its receptor, and that the density of FGFR expression might be a marker of the cytodifferentiation of PDL cells into mineralized tissue forming cells.

BAG-1 and Bcl-2 in IL-2 signaling

Some cytokines can prolong cell survival in hematolymphoid cells and thus may be crucial for regulation of hematolymphoid cell numbers. It has been shown that mitogenic cytokines can induce not only cellular proliferation but also cellular survival by inhibiting apoptosis in hematolymphoid cells. The signals transduced by these cytokines eventually go to the nucleus and induce expression of their specific target genes. In this context, the induction of anti-apoptotic molecules such as Bcl-2 oncoprotein and BAG-1 protein seems to be a key event for the anti-apoptotic function of cytokines. In T lymphocytes, the interaction of interleukin-2 (IL-2) with its receptor (IL-2R) induces both cellular proliferation and cellular survival. The IL-2R consists of three subunits, i.e., IL-2Ralpha, IL-2R(beta)c, and IL-2R(gamma)c chains. Structure-function analysis of the IL-2R(beta)c chain has revealed that there are at least two functional domains within the subunit. The serine-rich (S) region but not the acidic (A) region within the (beta)c chain is responsible for the mitogenic signaling of IL-2R. The S region is also crucial for the cellular survival signaling, which include the induction of anti-apoptotic gene expressions bcl-2 and bag-l. However, the cellular survival signaling is segregated from the mitogenic signaling in independence from the Jak-family protein kinase activation and rapamycin sensitivity. Segregation of the two signaling pathways of a cytokine receptor has also been shown in receptors of the other mitogenic cytokines. Current topics regarding signal transductions of cytokine receptors responsible for the suppression of apoptosis are discussed in this review.

Expression and location of Hsp70/Hsc-binding anti-apoptotic protein BAG-1 and its variants in normal tissues and tumor cell lines

BAG-1 is a multifunctional protein that blocks apoptosis and interacts with several types of proteins, including Bcl-2 family proteins, the kinase Raf-1, certain tyrosine kinase growth factor receptors, and steroid hormone receptors, possibly by virtue of its ability to regulate the Hsp70/Hsc70 family of molecular chaperones. Two major forms of the human and mouse BAG-1 proteins were detected by immunoblotting. The longer human and mouse BAG-1 proteins (BAG-1L) appear to arise through translation initiation at noncanonical CTG codons located upstream of and in-frame with the usual ATG codon used for production of the originally described BAG-1 protein. Immunoblotting experiments using normal tissues revealed that BAG-1L is far more restricted in its expression and is present at lower levels than the more prevalent BAG-1 protein. Human but not mouse tissues also produce small amounts of an additional isoform of BAG-1 of intermediate size (BAG-1M) that probably arises through translation initiation at yet another site involving an ATG codon. All three isoforms of human BAG-1 (BAG-1, BAG-1M, and BAG-1L) retained the ability to bind Hsc70. Subcellular fractionation and immunofluorescence confocal microscopy studies indicated that BAG-1L often resides in the nucleus, consistent with the presence of a nuclear localization sequence in the NH2-terminal unique domain of this protein. In immunohistochemical assays, BAG-1 immunoreactivity was detected in a wide variety of types of cells in normal adult tissues and was localized to either cytosol, nucleus, or both, depending on the particular type of cell. In some cases, cytosolic BAG-1 immunostaining was clearly associated with organelles resembling mitochondria, consistent with the reported interaction of BAG-1 with Bcl-2 and related proteins. Furthermore, experiments using a green fluorescence protein (GFP)-BAG-1 fusion protein demonstrated that overexpression of Bcl-2 in cultured cells can cause intracellular redistribution of GFP-BAG-1, producing a membranous pattern typical of Bcl-2 family proteins. The BAG-1 protein was found at high levels in several types of human tumor cell lines among the 67 tested, particularly leukemias, breast, prostate, and colon cancers. In contrast to normal tissues, which only rarely expressed BAG-1L, tumor cell lines commonly contained BAG-1L protein, including most prostate, breast, and leukemia cell lines, suggesting that a change in BAG-1 mRNA translation frequently accompanies malignant transformation.

Interaction of BAG-1 with retinoic acid receptor and its inhibition of retinoic acid-induced apoptosis in cancer cells

BAG-1 (also known as RAP46) is an anti-apoptotic protein, which has been shown previously to interact with a number of nuclear hormone receptors, including receptors for glucocorticoid, estrogen, and thyroid hormone. We show here that BAG-1 also interacts with retinoic acid receptor (RAR). Gel retardation assays demonstrated that in vitro translated BAG-1 protein could effectively inhibit the binding of RAR but not retinoid X receptor (RXR) to a number of retinoic acid (RA) response elements (RAREs). A glutathione S-transferase-BAG-1 fusion protein also specifically bound RAR but not RXR. Interaction of BAG-1 and RAR could also be demonstrated by yeast two-hybrid assays. In transient transfection assays, co-transfection of BAG-1 expression plasmid inhibited the transactivation activity of RAR/RXR heterodimers but not RXR/RXR homodimers. When stably expressed in breast cancer cell lines, BAG-1 inhibited binding of RAR/RXR heterodimer to a number of RAREs and suppressed RA-induced growth inhibition and apoptosis. In addition, RA-induced suppression of Bcl-2 expression was abrogated by overexpression of BAG-1. These results demonstrate that BAG-1 can regulate retinoid activities through its interaction with RAR and suggest that elevated levels of BAG-1 protein could potentially contribute to retinoid resistance in cancer cells.