Golgi apparatus-localized CATION CALCIUM EXCHANGER4 promotes osmotolerance of Arabidopsis

Calcium (Ca2+) is a major ion in living organisms, where it acts as a second messenger for various biological phenomena. The Golgi apparatus retains a higher Ca2+ concentration than the cytosol and returns cytosolic Ca2+ to basal levels after transient elevation in response to environmental stimuli such as osmotic stress. However, the Ca2+ transporters localized in the Golgi apparatus of plants have not been clarified. We previously found that a wild-type (WT) salt-tolerant Arabidopsis (Arabidopsis thaliana) accession, Bu-5, showed osmotic tolerance after salt acclimatization, whereas the Col-0 WT did not. Here, we isolated a Bu-5 background mutant gene, acquired osmotolerance-defective 6 (aod6), which reduces tolerance to osmotic, salt, and oxidative stresses, with a smaller plant size than the WT. The causal gene of the aod6 mutant encodes CATION CALCIUM EXCHANGER4 (CCX4). The aod6 mutant was more sensitive than the WT to both deficient and excessive Ca2+. In addition, aod6 accumulated higher Ca2+ than the WT in the shoots, suggesting that Ca2+ homeostasis is disturbed in aod6. CCX4 expression suppressed the Ca2+ hypersensitivity of the csg2 (calcium sensitive growth 2) yeast (Saccharomyces cerevisiae) mutant under excess CaCl2 conditions. We also found that aod6 enhanced MAP kinase 3/6 (MPK3/6)-mediated immune responses under osmotic stress. Subcellular localization analysis of mGFP-CCX4 showed GFP signals adjacent to the trans-Golgi apparatus network and co-localization with Golgi apparatus-localized markers, suggesting that CCX4 localizes in the Golgi apparatus. These results suggest that CCX4 is a Golgi apparatus-localized transporter involved in the Ca2+ response and plays important roles in osmotic tolerance, shoot Ca2+ content, and normal growth of Arabidopsis.

Mutations in nuclear pore complex promote osmotolerance in Arabidopsis by suppressing the nuclear translocation of ACQOS and its osmotically induced immunity

We have previously reported a wide variation in salt tolerance among Arabidopsis thaliana accessions and identified ACQOS, encoding a nucleotide-binding leucine-rich repeat (NLR) protein, as the causal gene responsible for the disturbance of acquired osmotolerance induced after mild salt stress. ACQOS is conserved among Arabidopsis osmosensitive accessions, including Col-0. In response to osmotic stress, it induces detrimental autoimmunity, resulting in suppression of osmotolerance, but how ACQOS triggers autoimmunity remains unclear. Here, we screened acquired osmotolerance (aot) mutants from EMS-mutagenized Col-0 seeds and isolated the aot19 mutant. In comparison with the wild type (WT), this mutant had acquired osmotolerance and decreased expression levels of pathogenesis-related genes. It had a mutation in a splicing acceptor site in NUCLEOPORIN 85 (NUP85), which encodes a component of the nuclear pore complex. A mutant with a T-DNA insertion in NUP85 acquired osmotolerance similar to aot19. The WT gene complemented the osmotolerant phenotype of aot19. We evaluated the acquired osmotolerance of five nup mutants of outer-ring NUPs and found that nup96, nup107, and aot19/nup85, but not nup43 or nup133, showed acquired osmotolerance. We examined the subcellular localization of the GFP-ACQOS protein and found that its nuclear translocation in response to osmotic stress was suppressed in aot19. We suggest that NUP85 is essential for the nuclear translocation of ACQOS, and the loss-of-function mutation of NUP85 results in acquired osmotolerance by suppressing ACQOS-induced autoimmunity in response to osmotic stress.

Domesticating Vigna stipulacea: Chromosome-Level genome assembly reveals VsPSAT1 as a candidate gene decreasing hard-seededness

To increase food production under the challenges presented by global climate change, the concept of de novo domestication-utilizing stress-tolerant wild species as new crops-has recently gained considerable attention. We had previously identified mutants with desired domestication traits in a mutagenized population of the legume Vigna stipulacea Kuntze (minni payaru) as a pilot for de novo domestication. Given that there are multiple stress-tolerant wild legume species, it is important to establish efficient domestication processes using reverse genetics and identify the genes responsible for domestication traits. In this study, we identified VsPSAT1 as the candidate gene responsible for decreased hard-seededness, using a Vigna stipulacea isi2 mutant that takes up water from the lens groove. Scanning electron microscopy and computed tomography revealed that the isi2 mutant has lesser honeycomb-like wax sealing the lens groove than the wild-type, and takes up water from the lens groove. We also identified the pleiotropic effects of the isi2 mutant: accelerating leaf senescence, increasing seed size, and decreasing numbers of seeds per pod. While doing so, we produced a V. stipulacea whole-genome assembly of 441 Mbp in 11 chromosomes and 30,963 annotated protein-coding sequences. This study highlights the importance of wild legumes, especially those of the genus Vigna with pre-existing tolerance to biotic and abiotic stresses, for global food security during climate change.

Recognition of Microbe- and Damage-Associated Molecular Patterns by Leucine-Rich Repeat Pattern Recognition Receptor Kinases Confers Salt Tolerance in Plants

In plants, a first layer of inducible immunity is conferred by pattern recognition receptors (PRRs) that bind microbe- and damage-associated molecular patterns to activate pattern-triggered immunity (PTI). PTI is strengthened or followed by another potent form of immunity when intracellular receptors recognize pathogen effectors, termed effector-triggered immunity. Immunity signaling regulators have been reported to influence abiotic stress responses as well, yet the governing principles and mechanisms remain ambiguous. Here, we report that PRRs of a leucine-rich repeat ectodomain also confer salt tolerance in Arabidopsis thaliana, following recognition of cognate ligands such as bacterial flagellin (flg22 epitope) and elongation factor Tu (elf18 epitope), and the endogenous Pep peptides. Pattern-triggered salt tolerance (PTST) requires authentic PTI signaling components; namely, the PRR-associated kinases BAK1 and BIK1 and the NADPH oxidase RBOHD. Exposure to salt stress induces the release of Pep precursors, pointing to the involvement of the endogenous immunogenic peptides in developing plant tolerance to high salinity. Transcriptome profiling reveals an inventory of PTST target genes, which increase or acquire salt responsiveness following a preexposure to immunogenic patterns. In good accordance, plants challenged with nonpathogenic bacteria also acquired salt tolerance in a manner dependent on PRRs. Our findings provide insight into signaling plasticity underlying biotic or abiotic stress cross-tolerance in plants conferred by PRRs.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

MAP KINASE PHOSPHATASE1 promotes osmotolerance by suppressing PHYTOALEXIN DEFICIENT4-independent immunity

Initial exposure of plants to osmotic stress caused by drought, cold, or salinity leads to acclimation, termed acquired tolerance, to subsequent severe stresses. Acquired osmotolerance induced by salt stress is widespread across Arabidopsis (Arabidopsis thaliana) accessions and is conferred by disruption of a nucleotide-binding leucine-rich repeat gene, designated ACQUIRED OSMOTOLERANCE. De-repression of this gene under osmotic stress causes detrimental autoimmunity via ENHANCED DISEASE SUSCEPTIBILITY1 and PHYTOALEXIN DEFICIENT4 (PAD4). However, the mechanism underlying acquired osmotolerance remains poorly understood. Here, we isolated an acquired osmotolerance-defective mutant (aod13) by screening 30,000 seedlings of an ion beam-mutagenized M2 population of Bu-5, an accession with acquired osmotolerance. We found that AOD13 encodes the dual-specificity phosphatase MAP KINASE PHOSPHATASE1 (MKP1), which negatively regulates MITOGEN-ACTIVATED PROTEIN KINASE3/6 (MPK3/6). Consistently, MPK3/6 activation was greater in aod13 than in the Bu-5 wild-type (WT). The aod13 mutant was sensitive to osmotic stress but tolerant to salt stress. Under osmotic stress, pathogenesis-related genes were strongly induced in aod13 but not in the Bu-5 WT. Loss of PAD4 in pad4 aod13 plants did not restore acquired osmotolerance, implying that activation of immunity independent of PAD4 renders aod13 sensitive to osmotic stress. These findings suggest that AOD13 (i.e. MKP1) promotes osmotolerance by suppressing the PAD4-independent immune response activated by MPK3/6.

ECERIFERUM 10 Encoding an Enoyl-CoA Reductase Plays a Crucial Role in Osmotolerance and Cuticular Wax Loading in Arabidopsis

Acquired osmotolerance induced after salt stress is widespread across Arabidopsis thaliana (Arabidopsis) accessions (e.g., Bu-5). However, it remains unclear how this osmotolerance is established. Here, we isolated a mutant showing an acquired osmotolerance-defective phenotype (aod2) from an ion-beam-mutagenized M2 population of Bu-5. aod2 was impaired not only in acquired osmotolerance but also in osmo-shock, salt-shock, and long-term heat tolerances compared with Bu-5, and it displayed abnormal morphology, including small, wrinkled leaves, and zigzag-shaped stems. Genetic analyses of aod2 revealed that a 439-kbp region of chromosome 4 was translocated to chromosome 3 at the causal locus for the osmosensitive phenotype. The causal gene of the aod2 phenotype was identical to ECERIFERUM 10 (CER10), which encodes an enoyl-coenzyme A reductase that is involved in the elongation reactions of very-long-chain fatty acids (VLCFAs) for subsequent derivatization into cuticular waxes, storage lipids, and sphingolipids. The major components of the cuticular wax were accumulated in response to osmotic stress in both Bu-5 WT and aod2. However, less fatty acids, primary alcohols, and aldehydes with chain length ≥ C30 were accumulated in aod2. In addition, aod2 exhibited a dramatic reduction in the number of epicuticular wax crystals on its stems. Endoplasmic reticulum stress mediated by bZIP60 was increased in aod2 under osmotic stress. The only cer10 showed the most pronounced loss of epidermal cuticular wax and most osmosensitive phenotype among four Col-0-background cuticular wax-related mutants. Together, the present findings suggest that CER10/AOD2 plays a crucial role in Arabidopsis osmotolerance through VLCFA metabolism involved in cuticular wax formation and endocytic membrane trafficking.

Potato Virus X Vector-Mediated DNA-Free Genome Editing in Plants

Genome editing technology is important for plant science and crop breeding. Genome-edited plants prepared using general CRISPR-Cas9 methods usually contain foreign DNA, which is problematic for the production of genome-edited transgene-free plants for vegetative propagation or highly heterozygous hybrid cultivars. Here, we describe a method for highly efficient targeted mutagenesis in Nicotiana benthamiana through the expression of Cas9 and single-guide (sg)RNA using a potato virus X (PVX) vector. Following Agrobacterium-mediated introduction of virus vector cDNA, >60% of shoots regenerated without antibiotic selection carried targeted mutations, while ≤18% of shoots contained T-DNA. The PVX vector was also used to express a base editor consisting of modified Cas9 fused with cytidine deaminase to introduce targeted nucleotide substitution in regenerated shoots. We also report exogenous DNA-free genome editing by mechanical inoculation of virions comprising the PVX vector expressing Cas9. This simple and efficient virus vector-mediated delivery of CRISPR-Cas9 could facilitate transgene-free gene editing in plants.

A removable virus vector suitable for plant genome editing

Plant genome editing is achieved by the expression of sequence-specific nucleases (SSNs). RNA virus vector-mediated expression of SSNs is a promising approach for transgene integration-free targeted mutagenesis in plants. However, the removal of virus vectors from infected plants is challenging because no antiviral drugs are available against plant viruses. Here, we developed a removable RNA virus vector that carries the target site of tobacco microRNA398 (miR398) whose expression is induced during shoot regeneration. In the inoculated leaves in which expression of miR398 is not induced, insertion of the miR398 target site did not affect the practicability of the virus vector. When shoots were regenerated from the infected leaves, miR398 was expressed and viral RNA was eliminated. The virus vector successfully expressed SSNs in inoculated leaves, from which virus-free genome-edited plants were regenerated via tissue culture.

NLR locus-mediated trade-off between abiotic and biotic stress adaptation in Arabidopsis

Osmotic stress caused by drought, salt or cold decreases plant fitness. Acquired stress tolerance defines the ability of plants to withstand stress following an initial exposure¹. We found previously that acquired osmotolerance after salt stress is widespread among Arabidopsis thaliana accessions². Here, we identify ACQOS as the locus responsible for ACQUIRED OSMOTOLERANCE. Of its five haplotypes, only plants carrying group 1 ACQOS are impaired in acquired osmotolerance. ACQOS is identical to VICTR, encoding a nucleotide-binding leucine-rich repeat (NLR) protein³. In the absence of osmotic stress, group 1 ACQOS contributes to bacterial resistance. In its presence, ACQOS causes detrimental autoimmunity, thereby reducing osmotolerance. Analysis of natural variation at the ACQOS locus suggests that functional and non-functional ACQOS alleles are being maintained due to a trade-off between biotic and abiotic stress adaptation. Thus, polymorphism in certain plant NLR genes might be influenced by competing environmental stresses.

Structure determination of the rutile-TiO2(110)-(1 × 2) surface using total-reflection high-energy positron diffraction (TRHEPD)

Detailed structure of the rutile-TiO₂(110)-(1 × 2) has been determined using the newly developed technique of total-reflection high-energy positron diffraction (TRHEPD).

Effect of 5-hydroxytryptamine receptor 4 agonist mosapride on human gastric accommodation

BACKGROUND

Impaired gastric accommodation is one of the major features of functional dyspepsia. Mosapride citrate is a 5-hydroxytryptamine receptor 4 (5-HT4) agonist, which is shown to improve upper abdominal symptoms. However, effect of mosapride on gastric accommodation was not clear. We tested the hypothesis that mosapride enhances the gastric accommodation in normal individuals.

METHODS

Fourteen male healthy volunteers completed this study. Single administration of mosapride or placebo was performed randomly with more than 1-week interval. Subjects swallowed a triple-lumen polyvinyl tube with a polyethylene bag. The bag was positioned in the proximal stomach and the minimal distending pressure (MDP) was determined. The ramp distension starting from the MDP was then performed and subjects were instructed to score their perception using ordinate scales. Next the intra-bag pressure was set at MDP + 2 mmHg and a liquid meal was administered 30 min later, and the intra-bag volume was recorded for 60 min. We compared the MDP, perception scores, and the intra-bag volume changes by administering placebo and mosapride.

KEY RESULTS

Minimal distending pressure was not significantly different in subjects receiving mosapride or placebo. Treatment with mosapride had no effect on intra-bag pressures or volumes inducing first sensation or discomfort. Gastric accommodation, expressed as the difference between pre- and postmeal intra-bag volumes, and the percent change of the intra-bag volumes by the meal was significantly enhanced by mosapride compared with placebo.

CONCLUSIONS & INFERENCES

This is the first study clearly demonstrating that single administration of 5-HT4 agonist can enhance gastric accommodation in humans. (Umin.ac.jp, number UMIN000014063).

CSP41b, a protein identified via FOX hunting using Eutrema salsugineum cDNAs, improves heat and salinity stress tolerance in transgenic Arabidopsis thaliana

Eutrema salsugineum (also known as Thellungiella salsuginea and formerly Thellungiella halophila), a species closely related to Arabidopsis thaliana, shows tolerance not only to salt stress, but also to chilling, freezing, and high temperatures. To identify genes responsible for stress tolerance, we conducted Full-length cDNA Over-eXpressing gene (FOX) hunting among a collection of E. salsugineum cDNAs that were stress-induced according to gene ontology analysis or over-expressed in E. salsugineum compared with A. thaliana. We identified E. salsugineum CSP41b (chloroplast stem-loop-binding protein of 41 kDa; also known as CRB, chloroplast RNA binding; named here as EsCSP41b) as a gene that can confer heat and salinity stress tolerance on A. thaliana. A. thaliana CSP41b is reported to play an important role in the proper functioning of the chloroplast: the atcsp41b mutant is smaller and paler than wild-type plants and shows altered chloroplast morphology and photosynthetic performance. We observed that AtCSP41b-overexpressing transgenic A. thaliana lines also exhibited marked heat tolerance and significant salinity stress tolerance. The EsCSP41b-overexpressing transgenic A. thaliana lines showed significantly higher photosynthesis activity than wild-type plants not only under normal growth conditions but also under heat stress. In wild-type plants, the expression levels of both EsCSP41b and AtCSP41b were significantly reduced under heat or salinity stress. We conclude that maintenance of CSP41b expression under abiotic stresses may alleviate photoinhibition and improve survival under such stresses.

Arabidopsis sos1 mutant in a salt-tolerant accession revealed an importance of salt acclimation ability in plant salt tolerance

An analysis of the salinity tolerance of 354 Arabidopsis thaliana accessions showed that some accessions were more tolerant to salt shock than the reference accession, Col-0, when transferred from 0 to 225 mM NaCl. In addition, several accessions, including Zu-0, showed marked acquired salt tolerance after exposure to moderate salt stress. It is likely therefore that Arabidopsis plants have at least two types of tolerance, salt shock tolerance and acquired salt tolerance. To evaluate a role of well-known salt shock tolerant gene SOS1 in acquired salt tolerance, we isolated a sos1 mutant from ion-beam-mutagenized Zu-0 seedlings. The mutant showed severe growth inhibition under salt shock stress owing to a single base deletion in the SOS1 gene and was even more salt sensitive than Col-0. Nevertheless, it was able to survive after acclimation on 100 mM NaCl for 7 d followed by 750 mM sorbitol for 20 d, whereas Col-0 became chlorotic under the same conditions. We propose that genes for salt acclimation ability are different from genes for salt shock tolerance and play an important role in the acquisition of salt or osmotic tolerance.

Results of chemoradiotherapy for stage I esophageal cancer in medically inoperable patients compared with results in operable patients

The purpose of the present study was to evaluate long-term results of chemoradiotherapy for clinical T1b-2N0M0 esophageal cancer and to compare outcomes for operable and inoperable patients. Patients with stage I esophageal cancer (Union for International Cancer Control [UICC] 2009), excluding patients with cT1a esophageal cancer, were studied. All patients had histologically proven squamous cell carcinoma. Operable patients received cisplatin and 5-fluorouracil with concurrent radiotherapy of 60 Gy including a 2-week break. Inoperable patients received nedaplatin and 5-fluorouracil with concurrent radiotherapy of 60-70 Gy without a pause. End-points were overall survival rate (OS), cause-specific survival rate (CSS), progression-free survival rate (PFS), and locoregional control rate (LC). Thirty-seven operable patients and 30 medically inoperable patients were enrolled. There was a significant difference in only age between the operable group and inoperable group (P = 0.04). The median observation period was 67.9 months. In all patients, 5-year OS, CSS, PFS, and LC were 77.9%, 91.5%, 66.9%, and 80.8%, respectively. Comparison of the operable group and inoperable group showed that there was a significant difference in OS (5-year, 85.5% vs. 68.7%, P = 0.04), but there was no difference in CSS, PFS, or LC. Grade 3 or more late toxicity according to Common Terminology Criteria for Adverse Events v 3.0 was found in seven patients. Even in medically inoperable patients with stage I esophageal cancer, LC of more than 80% can be achieved with chemoradiotherapy. However, OS in medically inoperable patients is significantly worse than that in operable patients.

Ghrelin regulates gastric phase III-like contractions in freely moving conscious mice

In humans and dogs, motilin regulates phase III contractions of migrating motor complex (MMC) in the interdigestive state, while ghrelin regulates MMC in rats. It still remains unclear whether ghrelin regulates phase III contractions of the mouse stomach. A miniature strain gauge transducer was sutured on the antrum to detect circular muscle contractions and gastric contractions of the interdigestive state were evaluated. Effects of ghrelin, a ghrelin receptor antagonist, and atropine on spontaneous gastric contractions were studied in freely moving conscious mice. Similar to the rat stomach, phase III-like contractions were observed in the interdigestive state, which disappeared immediately after the feeding. Ghrelin augmented spontaneous phase III-like contractions, while growth-hormone secretagogue receptor antagonists and atropine abolished the occurrence of spontaneous phase III-like contractions. The spontaneous phase III-like contractions were no more observed in vagotomized mice. These results suggest that ghrelin regulates phase III-like contractions in mice stomach via its own receptors. Ghrelin-induced gastric phase III-like contractions are mediated via vagal cholinergic pathways in mice. Our recording system of mice gastric motility may be useful to study the functional changes in gene knockout mice, in the future.

Correlation between DJ-1 levels in the cerebrospinal fluid and the progression of disabilities in multiple sclerosis patients

Objectives

DJ-1 plays a key role in the anti-oxidative stress function. Increasing evidence supports the role of oxidative stress in the pathogenesis of multiple sclerosis (MS). The aim of this study was to investigate whether the DJ-1 levels were increased in patients with MS and to examine its association with the progression of MS.

Methods

Quantitative immunoblot assays were performed to evaluate the DJ-1 level in serum and cerebrospinal fluid (CSF) collected from relapsing–remitting patients with MS ( n = 29), disease controls subjects ( n = 14), and healthy subjects ( n = 44).

Results

No significant difference was observed in the serum DJ-1 level among the patients with MS, disease controls, and healthy controls. However, the CSF DJ-1 levels were significantly higher in the patients with MS than in the disease control subjects ( P < 0.0001). A significant positive correlation was also found between the CSF DJ-1 levels and the Multiple Sclerosis Severity Score ( P < 0.005, r = 0.501).

Conclusions

These results show that the CSF DJ-1 levels are significantly increased in the CSF of patients with MS and that the CSF DJ-1 levels may be associated with the disease progression of MS. Therefore, DJ-1 possibly plays an important role in the pathogenesis of MS.

Endogenous acyl ghrelin is involved in mediating spontaneous phase III-like contractions of the rat stomach

In humans and dogs, it is known that motilin regulates phase III contractions of migrating motor complex (MMC) in the fasted state. In rats, however, motilin and its receptor have not been found, and administration of motilin failed to induce any phase III-like contractions. Ghrelin was discovered as the endogenous ligand for the growth hormone secretagogue receptor (GHS-R) from the rat stomach. Ghrelin promotes gastric premature phase III (phase III-like contractions) in the fasted state in rats. We hypothesized that endogenous ghrelin regulates spontaneous phase III-like contractions in rats. Strain gauge transducer was sutured on the antrum and a catheter was inserted into the jugular vein. We studied the effects of i.v. administration of ghrelin and a GHS-R antagonist on gastric phase III-like contractions in conscious rats. Plasma level of ghrelin was measured by a radioimmunoassay. Ghrelin augmented spontaneous phase III-like contractions and a GHS-R antagonist significantly attenuated the occurrence of spontaneous phase III-like contractions. During the phase I period, plasma ghrelin level increased to its peak then returned to basal level, subsequently phase III-like contractions were observed. These results suggest that endogenous ghrelin regulates gastric phase III-like contractions in rats.

Proper SUMO-1 conjugation is essential to DJ-1 to exert its full activities

DJ-1 is a multifunctional protein that plays roles in transcriptional regulation and antioxidative stress, and loss of its function is thought to result in the onset of Parkinson's disease (PD). Here, we report that DJ-1 was sumoylated on a lysine residue at amino-acid number 130 (K130) by PIASxalpha or PIASy. The K130 mutation abrogated all of the functions of DJ-1, including ras-dependent transformation, cell growth promotion and anti-UV-induced apoptosis activities. Sumoylation of DJ-1 was increased after UV irradiation concomitant with a pI shift to an acidic point of DJ-1. Furthermore, L166P, a mutant DJ-1 found in PD patients, and K130RX, an artificial mutant containing four mutations in DJ-1, were improperly sumoylated, and they became insoluble, partly localized in the mitochondria and degraded by the proteasome system. Both L166P-expressing cells and DJ-1-knockdown cells were found to be highly susceptible to UV-induced cell apoptosis.

The natural history of maternal immunization against foetal platelet alloantigens

Foetomaternal alloimmune thrombocytopenia (FMAIT) occurs when maternal antibodies of an antigen-negative mother cause destruction of sensitized foetal platelets. In Caucasian populations, 6-12% of human platelet antigen (HPA)-1a-negative women develop anti-HPA-1a, and the incidence of clinically affected cases is estimated to be 10-20% of immunized women. This study was performed in order to elucidate the rate of maternal immunization, incidence of FMAIT and the likely outcome of the condition in Asians. Excluding two or more pregnancies during the period, serum samples from 24 630 pregnant women, mainly Japanese, were screened for antibodies against platelet alloantigens by means of mixed passive haemagglutination (MPHA) (Anti-HPA-MPHA, Olympus, Tokyo). Antibodies were detected in 0.91% (223/24 630) of the women's samples and the immunization rate was correlated with the number of pregnancies. Antibody specificity included anti-HPA-4b (49), anti-HPA-5a (three), anti-HPA-5b (168), anti-HPA-4b + 5b (one) and anti-Nak(a) (CD36) (two). No alloimmunization was observed within the HPA-1, HPA-2, HPA-3 or HPA-6 systems. Among HPA-4b- or HPA-5b-negative women, 24% or 14% estimated, respectively, had antibodies and 26% (10/38) or 10% (12/125) of neonates, respectively, born to these mothers developed thrombocytopenia. Two neonates born to mothers having anti-HPA-4b developed generalized purpura. No cases of intracranial bleeding or death due to FMAIT were recorded. Generalized purpura due to FMAIT occurs in one in 9359 (95% CI: 1 in 77 519-1 in 2591) pregnancies solely because of HPA-4b incompatibility.

A novel transrepression pathway of c-Myc. Recruitment of a transcriptional corepressor complex to c-Myc by MM-1, a c-Myc-binding protein

The protooncogene product c-Myc plays a role in transcription regulation both for activation and repression. While transactivation pathways of c-Myc either from the N-proximal or the C-proximal region that is linked to the chromatin remodeling complex have been identified, a transrepression pathway had been identified only from the C-proximal region via Max and Mad that recruit the histone deacetylase (HDAC) complex. We have reported that a novel c-Myc-binding protein, MM-1, repressed the E-box-dependent transcription activity of c-Myc (Mori, K., Maeda, Y., Kitaura, H., Taira, T., Iguchi-Ariga, S. M. M., and Ariga, H. (1998) J. Biol. Chem. 273, 29794-29800). To clarify the molecular mechanisms of MM-1 toward c-Myc, cDNAs encoding MM-1-binding proteins were screened by the two-hybrid method with MM-1 as a bait using a human HeLa cDNA library, and a cDNA encoding TIF1 beta/KAP1, a transcriptional corepressor, was obtained. MM-1 was found to bind to the central portion of TIF1 beta in vitro and in vivo, and these proteins were found to be colocalized in the nucleus. MM-1 and TIF1 beta complex in human HeLa cells was found to also contain c-Myc, mSin3, and HDAC1. Introduction of the C-terminal half of TIF1 beta as a dominant negative form abrogated the inhibitory activity of MM-1 toward c-Myc and greatly stimulated the transcription activity of c-Myc. Moreover, the inhibitory activity of MM-1 toward c-Myc was canceled by trichostatin A, an inhibitor of HDAC1. These results indicate that MM-1 is a connecting factor that forms a novel transcription repression pathway of c-Myc.

Tumour invasion and metastasis are promoted in mice deficient in tenascin-X

BACKGROUND

Tenascin-X (TNX) is a member of the tenascin family of large oligomeric glycoproteins of the extracellular matrix (ECM). To determine whether TNX plays a part in tumour invasion and metastasis and to disclose its normal physiological role, we disrupted its gene in mouse embryonic stem cells by homologous recombination and created mice deficient in TNX.

RESULTS

TNX-null mutant (TNX-/-) mice arose at normal frequency and showed no obvious defects during their adult life. However, when TNX-/- mice were subcutaneously inoculated in foot-pads with a highly invasive and metastatic cell line, B16-BL6 melanoma cells, the primary tumour size at 30 days after inoculation in the TNX-/- mice had increased by 1.2-fold compared with that in wild-type mice, and the invasion to the ankle and pulmonary metastasis in TNX-/- mice were also augmented by 2.2-fold and 6.8-fold, respectively, compared to those in wild-type mice. To disclose the molecular mechanism(s) of the promotion of tumour invasion and metastasis in TNX-/- mice, we measured the protein levels of matrix metalloproteinases (MMPs), which are recognized as playing a key role in these events, in the foot-pad homogenates of TNX-/- mice prior to the inoculation of melanoma cells. Gelatin zymography showed that the activities of proMMP-2, active MMP-2 and proMMP-9 were significantly higher in TNX-/- mice than in wild-type mice. Furthermore, a Northern blot analysis demonstrated that this increased activity of MMP-2 in TNX-/- mice was due to the induced expression of MMP-2 at the transcriptional level. The elevated expression of MMP-2 and MMP-9 resulted in decreased laminin levels, to less than half that of wild-type mice in the homogenates of TNX-/- mice.

CONCLUSIONS

TNX deficiency led to an increase in the production of MMPs, and the increased activity of MMPs may result in the degradation of laminin. Consequently, the melanoma cells inoculated in TNX-/- mice might facilitate invasion and metastasis. These results imply that TNX is required for impeding the invasion and metastasis of tumour cells.

Disruption of MSSP, c-myc single-strand binding protein, leads to embryonic lethality in some homozygous mice

BACKGROUND

MSSP, c-myc single-strand binding protein, works as a factor for DNA replication, transcription, apoptosis induction, and myc/ras cooperative transformation. The cDNAs encoding four of the family proteins, MSSP-1, MSSP-2, Scr2 and Scr3, were cloned. These proteins possess two copies of putative RNA binding domains, RNP-A and RNP-B, and these RNA binding domains have been suggested to be indispensable to the functions of MSSP.

RESULTS

To elucidate its role in vivo, we generated Mssp knockout mice by homologous recombination in embryonic stem cells. Although intercrossing of Mssp+/- mice gave rise to mice homozygous to the mutant Mssp allele (Mssp-/-) and the Mssp-/- mice, once born, did not display an overt phenotype, the ratio of littermates born among Mssp+/+, Mssp+/- and Mssp-/- mice was 1 : 1.6 : 0.5, which is not a typical Mendelian ratio. When E2.5 embryos from the pregnant mice were cultured in vitro for 5 days, the inner cell mass and trophoblast giant cells in wild-type (Mssp+/+) E2.5 embryos developed normally. However, Mssp-/- E2.5 embryos displayed significant defects in growth and development. Since Mssp was expressed in uterine gland-transported glycogen, we evaluated the hormonal state of wild-type and Mssp-/- mice. The progesterone concentration of Mssp-/- mice was decrease to 6.5% of that of wild-type mice at E2.5.

CONCLUSIONS

These results suggest that the deletion of the mssp gene results in both the growth defect in the embryo and the hormonal defect in adult female mouse. The embryonic defect and a decreased concentration of progesterone in female mice reflect a development defect of the pre-implantation embryo in Mssp-/- mice, thereby leading to embryonic lethality.

Kinetics of fetal cellular and cell-free DNA in the maternal circulation during and after pregnancy: implications for noninvasive prenatal diagnosis

BACKGROUND

Fetal genetic material is detectable in the maternal circulation and has been used for noninvasive prenatal diagnosis. However, few data are available concerning its quantity and natural history during gestation.

STUDY DESIGN AND METHODS

This study prospectively characterized the kinetics of cellular and cell-free fetal DNA in the circulation of 25 healthy women during and after uncomplicated pregnancy. Real-time kinetic PCR was used to quantitate human Y-chromosome sequences, and liquid oligomer hybridization with (32)P-labeled probes was used to verify the identity of amplified products.

RESULTS

In all male pregnancies, but no female pregnancies, low-level fetal Y-chromosome DNA was detected in both cellular and cell-free compartments beginning at 7 to 16 weeks but increasing steadily after 24 weeks and reaching a peak at parturition. The fetal DNA decreased rapidly after birth.

CONCLUSION

Fetal genetic material can be detected throughout pregnancy, and its quantity is a function of gestational age and of whether the plasma or cellular compartment is examined. Both the absolute quantity of fetal DNA and its ratio to total DNA (maternal + fetal) are greater in the plasma than in the cellular compartment. Fetal DNA is cleared rapidly from both compartments after parturition, which suggests that turnover is dynamic. Because they provide prospective and quantitative data concerning fetal DNA levels, these observations and kinetic PCR methods may have implications for noninvasive prenatal diagnosis. Further studies will be needed to determine the immunologic implications of fetal-maternal DNA exchange and cellular microchimerism.

MM-1, a c-Myc-binding protein, is a candidate for a tumor suppressor in leukemia/lymphoma and tongue cancer

The c-myc oncogene product (c-Myc) is a transcription factor that dimerizes with Max and recognizes the E-box sequence, and it plays key functions in cell proliferation, differentiation, and apoptosis. We previously showed that MM-1 bound to myc box II within the transactivation domain of c-Myc and repressed the E-box-dependent transcriptional activity of c-Myc. Here we report that MM-1 showed features of a tumor suppressor. In an EST data base search for cDNAs homologous to MM-1, we found a frequent substitution of amino acid 157 of MM-1, from alanine to arginine (A157R), and the substitution was observed more in tumor cells than in normal cells. A survey of the A157R mutation of MM-1 in 57 cultured cancer cells and 90 tissues from cancer patients showed that the A157R was present in about 50-60% of leukemia/lymphoma cells and in more than 75% of squamous cell carcinoma of tongue cancer. Although both the A157R and the wild-type MM-1 bound to c-Myc, only A157R lost the activities to repress both the E-box-dependent transcriptional activity of c-Myc and the myc/ras cooperative transforming activity in rat 3Y1 cells. Furthermore, the wild-type MM-1, but not A157R, arrested the growth of 3Y1 cells. The human MM-1 gene was mapped at chromosome 12q12-12q13, where many chromosome abnormalities in cancer cells have been reported. The results suggest that MM-1 is a novel candidate for a tumor suppressor that controls the transcriptional activity of c-Myc.

Effect of tenascin-X together with vascular endothelial growth factor A on cell proliferation in cultured embryonic hearts

Tenascin-X (TNX) is a large glycoprotein that appears in extracellular matrices. Previously, we demonstrated that TNX binds to vascular endothelial growth factors A and B (VEGF-A and -B) and that VEGF-B in combination with TNX induces DNA synthesis in endothelial cells via increased signals mediated by the VEGFR-1 receptor. In this study, we investigated the effect of TNX with VEGF-A on the cell proliferation in embryonic mouse heart explants from either wild-type (TNX+/+) or TNX-deficient (TNX-/-) mice. The addition of VEGF-A to the explants from TNX+/+ mice increased cell proliferation by 1.5 fold compared with that in TNX-/- mice, indicating that TNX with VEGF family member plays an important role in the control of endothelial cell proliferation in vivo.

Radiation therapy for loco-regionally recurrent esophageal cancer after surgery

PURPOSE

To evaluate the treatment outcome of radiation therapy for 33 loco-regionally recurrent esophageal cancer patients.

METHODS

Between 1988 and 1997, 33 patients with loco-regional recurrence of esophageal cancer after curative surgery received radiation therapy at an average total dose of 61 Gy. The site of recurrence was the supraclavicular region in 14 patients, the mediastinal region in 13 patients, and both the supraclavicular and mediastinal regions in six patients. If patients had ether distant metastasis or malignant pleural effusion, they were excluded from analysis. Patients who received prophylactic postoperative irradiation were also excluded from analysis.

RESULTS

The median survival period was 7 months. The survival rates at 1, 2, and 3 years were 33, 15, and 12%, respectively. In univariate analysis, patients with a short time interval between surgery and recurrence (P=0.0098) and patients with recurrence in both the supraclavicular and mediastinal regions (P=0.036) had a worse prognosis. In multivariate analysis, the time interval between surgery and recurrence (P<0.001) and age (worse prognosis in younger patients, P=0.019) were the significant prognostic factors. Complete or partial responses were observed in nine (27%) and 21 (64%) of the patients, respectively. Changes in clinical symptoms, such as dysphagia, chest pain and back pain, could be evaluated in 11 patients, and improvement in symptoms was obtained in eight (73%) patients.

CONCLUSIONS

The prognosis of patients who received radiation therapy for postoperative loco-regional recurrence of esophageal cancer is poor. However, there is symptomatic relief in a significant proportion of such patients, and long-term survival is possible in some patients.

DJ-1 positively regulates the androgen receptor by impairing the binding of PIASx alpha to the receptor

DJ-1 was first identified as a novel candidate of the oncogene product that transformed mouse NIH3T3 cells in cooperation with an activated ras. Later DJ-1 was also found to be an infertility-related protein that was reduced in rat sperm treated with sperm toxicants that cause infertility in rats. To determine the functions of DJ-1, cDNAs encoding DJ-1-binding proteins were screened by the yeast two-hybrid method. Of several proteins identified, PIASx alpha/ARIP3, a modulator of androgen receptor (AR), was first characterized as the DJ-1-binding protein in this study. DJ-1 directly bound to the AR-binding region of PIASx alpha by an in vitro coimmunoprecipitation assay and also bound to PIASx alpha in human 293T cells. Both proteins were co-localized in the nuclei. PIASx alpha inhibited the AR transcription activity in a dose-dependent manner in cotransfected monkey CV1 cells with an androgen responsive element-luciferase reporter. Introduction of DJ-1 into CV1 cells in a state of inhibition of AR activity by PIASx alpha restored AR transcription activity by absorbing PIASx alpha from the AR-PIASx alpha complex, while a DJ-1 mutant harboring an amino acid substitution at number 130 from lysine to arginine did not restore it. These results indicate that DJ-1 is a positive regulator of the androgen receptor.

Pim-1 translocates sorting nexin 6/TRAF4-associated factor 2 from cytoplasm to nucleus

Pim-1, an oncogene product of serine/threonine kinase, has been found to play roles in apoptosis induction/suppression, cell-cycle progression and transcriptional regulation by phosphorylating the target proteins involved in these processes. The target proteins phosphorylated by Pim-1, including p100, Cdc25A, PAP-1 and heterochromatin protein 1, have been identified. The precise functions of Pim-1, however, are still poorly understood. In this study, we identified tumor necrosis factor receptor-associated factor 4-associated factor 2/sorting nexin 6 (TFAF2/SNX6) as a Pim-1-binding protein, and we found that TFAF2/SNX6 was phosphorylated and translocated from the cytoplasm to nucleus by Pim-1. This translocation of the protein was not affected by Pim-1-dependent phosphorylation. Since sorting nexins, including TFAF2/SNX6, have been reported to be located in the cytoplasm or membrane by association with several receptors of tyrosine- or serine/threonine-kinase, this is the first report of TFAF2/SNX6 being located in the nucleus after binding to Pim-1.

AMY-1, a c-Myc-binding protein, is localized in the mitochondria of sperm by association with S-AKAP84, an anchor protein of cAMP-dependent protein kinase

We have reported that a novel c-Myc-binding protein, AMY-1 (associate of Myc-1), stimulated the transcription activity of c-Myc. To access the molecular function of AMY-1, a two-hybrid screening of cDNAs encoding AMY-1-binding proteins was carried out with AMY-1 as a bait using a human HeLa cDNA library, and a clone encoding cAMP-dependent protein kinase anchor protein 149 (AKAP149), was obtained. AMY-1 was found to bind in vitro and in vivo to the regulatory subunit II binding region of AKAP149 and S-AKAP84, a splicing variant of AKAP149 expressed in the testis. AMY-1 was expressed postmeiotically in the testis, as S-AKAP84 was expressed. Furthermore, S-AKAP84 and regulatory subunit II, a regulatory subunit of cAMP-dependent protein kinase, made a ternary complex in cells, and AMY-1 was localized in the mitochondria of HeLa and sperm in association with AKAP149 and S-AKAP84, respectively. These results suggest that AMY-1 plays a role in spermatogenesis.

Initial symptoms of acute radiation syndrome in the JCO criticality accident in Tokai-mura

A criticality accident occurred on September 30, 1999, at the uranium conversion plant in Tokai-mura (Tokai-village), Ibaraki Prefecture, Japan. When the criticality occurred, three workers saw a "blue-white glow," and a radiation monitor alarm was sounded. They were severely exposed to neutron and gamma-ray irradiation, and subsequently developed acute radiation syndrome (ARS). One worker reported vomiting within minutes and loss of consciousness for 10-20 seconds. This worker also had diarrhea an hour after the exposure. The other worker started to vomit almost an hour after the exposure. The three workers, including their supervisor, who had no symptoms at the time, were brought to the National Mito Hospital by ambulance. Because of the detection of gamma-rays from their body surface by preliminary surveys and decreased numbers of lymphocytes in peripheral blood, they were transferred to the National Institute of Radiological Sciences (NIRS), which has been designated as a hospital responsible for radiation emergencies. Dose estimations for the three workers were performed by prodromal symptoms, serial changes of lymphocyte numbers, chromosomal analysis, and 24Na activity. The results obtained from these methods were fairly consistent. Most of the data, such as the dose rate of radiation, its distribution, and the quality needed to evaluate the average dose, were not available when the decision for hematopoitic stem cell transplantation had to be made. Therefore, prodromal symptoms may be important in making decisions for therapeutic strategies, such as stem-cell transplantation in heavily exposed victims.

Novel role of phosphatidylinositol 3-kinase in CD28-mediated costimulation

Ligation of the CD28 surface receptor provides a major costimulatory signal for full scale T cell activation. Despite extensive studies, the intracellular signaling pathways delivered by CD28 ligation are not fully understood. A particularly controversial matter is the role of phosphatidylinositol 3-kinase (PI3K) in CD28-mediated costimulation. It is known that the binding site for PI3K and Grb-2 lies nested within the YMNM motif of the CD28 cytoplasmic domain. To elucidate the role of PI3K during CD28-mediated interleukin-2 (IL-2) production, CD28 YMNM point and deletion mutants were expressed in Jurkat cells. We then measured IL-2 promoter activation after CD28 ligation. Our results showed that the Y189F mutant, which disrupts binding by PI3K, and the YMNM deletion mutant both demonstrated reduced but significant activity for IL-2 promoter activation. In contrast, the N191A mutant, which retains PI3K binding ability, resulted in a complete abrogation of activity, suggesting that PI3K mediates a negative effect upon transcriptional activation of the IL-2 gene. Consistent with this idea, we found that the addition of a PI3K pharmacological inhibitor augmented IL-2 promoter activity, whereas coexpression of a constitutively active form of PI3K reduced this activity. Taken together, these data indicate that PI3K, when associated with the YMNM motif, may act as a negative mediator in CD28-mediated IL-2 gene transcription.

Molecular cloning of human and mouse DJ-1 genes and identification of Sp1-dependent activation of the human DJ-1 promoter

DJ-1 has been identified as a novel oncogene that transforms mouse NIH3T3 cells in cooperation with activated ras. Subsequently, two other groups have identified SP22 or CAP-1, rat homologs of human DJ-1, as a sperm protein targeted by some toxicants leading to male infertility, and another group has also reported that RS, the same as human DJ-1, is a component of an RNA-binding protein complex. To characterize the expression or functional importance of DJ-1, the genomic DNAs of both human and mouse DJ-1 were cloned and characterized. Both genomic DNAs comprise 7 exons spanning about 16-24 kb, in which 2-6 exons encode the DJ-1 protein. The human DJ-1 gene was mapped at chromosome 1p36.2-p36.3, a region that has been shown to be a hot spot of chromosome abnormalities in several tumor cells. To analyze the promoter of the human DJ-1 gene, a series of deletion constructs of the region upstream of exon 2 were linked to the luciferase gene, and their luciferase activities were measured in human HeLa cells. Of the many putative transcription regulatory sequences, the Sp1 site present at -100 from the transcription initiation site contributed to the major promoter activity, and Sp1 was identified as a protein binding to this site by a mobility shift assay using HeLa nuclear extract.

Phase Ia study of a hypoxic cell sensitizer doranidazole (PR-350) in combination with conventional radiotherapy

A phase Ia study of a 2-nitroimidazole nucleoside analog radiosensitizer doranidazole was conducted to evaluate its toxicity and pharmacokinetics in patients undergoing conventional external beam radiotherapy. Twenty-nine patients, aged 40-74 years, with a WHO performance status of 0-2 and with adequate organ functions, were entered in the study. Single administration of doranidazole was investigated first with 13 patients and then a course of five consecutive daily administrations was tested in 16 patients. Doranidazole was given i.v. 25 min before irradiation. Doranidazole doses of 400, 800, 1300 and 2000 mg/m2 were evaluated in the former study, and daily doses of 800, 1300 and 2000 mg/m2 were investigated in the latter study. All patients tolerated doranidazole administration. Although a transient decrease in the 24-h creatinine clearance rate was observed in five patients (one in the single administration study and four in the repeat administration study), this was not considered to be the dose-limiting toxicity. Other toxicities (hematological and gastrointestinal), which may not be related to doranidazole administration, were also mild and were not dose limiting. No neurotoxicity was observed. The average maximum concentration, area under the time-concentration curve and half-life of doranidazole in serum were 172-194 microg/ml, 502-582 microg x h/l and 4.2-4.6 h, respectively, at 2000 mg/m2. At the tested doses, administration of doranidazole was tolerable and achieved serum concentrations at which reasonable radiosensitization could be expected. A phase Ib/II study to evaluate the feasibility and efficacy of up to 30 repeat administrations seems to be warranted.