Rice Putative Pectin Methyltransferase Gene OsPMT10 Is Required for Maintaining the Cell Wall Properties of Pistil Transmitting Tissues via Pectin Modification.

Precise directional control of pollen tube growth via mechanical guidance by pistil tissue is critical for the successful fertilization of flowering plants and requires active cell-to-cell communication and maintenance of softness in the transmitting tissue. However, the regulation of transmitting tissue softness as controlled by cell wall properties, especially pectin, has not been reported. Here we report that regulation of pectin methylesterification supports pollen elongation through pistil transmitting tissues in Oryza sativa. The rice pectin methylesterase gene OsPMT10 was strongly expressed in reproductive tissues, especially the pistil. The ospmt10 mutant did not have a significant effect on vegetative growth, but the fertility rate was reduced by approximately half. In the ospmt10 mutant, pollen tube elongation was observed in the transmitting tissue of the style, but approximately half of the pollen tubes did not extend all the way to the ovule. Tissue cross-sections of the upper ovary were prepared, and immunohistochemical staining using LM19 and LM20 showed that methylesterified pectin distribution was decreased in ospmt10 compared with the wild type. The decreased expression of methylesterified pectins in ospmt10 may have resulted in loss of fluidity in the apoplast space of the transmitting tissue, rendering it difficult for the pollen tube to elongate in the transmitting tissue and thereby preventing it from reaching the ovule.

Structural Alteration of Rice Pectin Affects Cell Wall Mechanical Strength and Pathogenicity of the Rice Blast Fungus Under Weak Light Conditions.

Pectin, a component of the plant cell wall, is involved in cell adhesion and environmental adaptations. We generated OsPG-FOX rice lines with little pectin due to overexpression of the gene encoding a pectin-degrading enzyme [polygalacturonase (PG)]. Overexpression of OsPG2 in rice under weak light conditions increased the activity of PG, which increased the degradation of pectin in the cell wall, thereby reducing adhesion. Under weak light conditions, the overexpression of OsPG decreased the pectin content and cell adhesion, resulting in abnormally large intercellular gaps and facilitating invasion by the rice blast fungus. OsPG2-FOX plants had weaker mechanical properties and greater sensitivity to biotic stresses than wild-type (WT) plants. However, the expression levels of disease resistance genes in non-infected leaves of OsPG2-FOX were more than twice as high as those of the WT and the intensity of disease symptoms was reduced, compared with the WT. Under normal light conditions, overexpression of OsPG2 decreased the pectin content, but did not affect cell adhesion and sensitivity to biotic stresses. Therefore, PG plays a role in regulating intercellular adhesion and the response to biotic stresses in rice.

Cell wall Glycine-rich Protein2 is involved in tapetal differentiation and pollen maturation.

The tapetum plays important roles in anther development by providing materials for pollen-wall formation and nutrients for pollen development. Here, we report the characterization of a male-sterile mutant of glycine-rich protein 2 (OsGRP2), which exhibits irregular cell division and dysfunction of the tapetum. GRP is a cellwall structural protein present in the cell walls of diverse plant species, but its function is unclear in pollen development. We found that few GRP genes are expressed in rice and thus focused on one highly expressed gene, OsGRP2. The tapetal cell walls of an OsGRP2 mutant did not thicken at the pollen mothercell stage, as a result, pollen maturation and fertility rate decreased. High OsGRP2 expression was detected in male-floral organs, and OsGRP2 was distributed in the tapetum. OsGRP2 participated in establishment of the cellwall network during early tapetum development. In conclusion, our results indicate that OsGRP2 plays important roles in the differentiation and function of the tapetum.

CADM1 associates with Hippo pathway core kinases; membranous co-expression of CADM1 and LATS2 in lung tumors predicts good prognosis.

Cell adhesion molecule-1 (CADM1) is a member of the immunoglobulin superfamily that functions as a tumor suppressor of lung tumors. We herein demonstrated that CADM1 interacts with Hippo pathway core kinases and enhances the phosphorylation of YAP1, and also that the membranous co-expression of CADM1 and LATS2 predicts a favorable prognosis in lung adenocarcinoma. CADM1 significantly repressed the saturation density elevated by YAP1 overexpression in NIH3T3 cells. CADM1 significantly promoted YAP1 phosphorylation on Ser 127 and downregulated YAP1 target gene expression at confluency in lung adenocarcinoma cell lines. Moreover, CADM1 was co-precipitated with multiple Hippo pathway components, including the core kinases MST1/2 and LATS1/2, suggesting the involvement of CADM1 in the regulation of the Hippo pathway through cell-cell contact. An immunohistochemical analysis of primary lung adenocarcinomas (n = 145) revealed that the histologically low-grade subtype frequently showed the membranous co-expression of CADM1 (20/22, 91% of low-grade; 61/91, 67% of intermediate grade; and 13/32, 41% of high-grade subtypes; P < 0.0001) and LATS2 (22/22, 100% of low-grade; 44/91, 48% of intermediate-grade; and 1/32, 3% of high-grade subtypes; P < 0.0001). A subset analysis of disease-free survival revealed that the membranous co-expression of CADM1 and LATS2 was a favorable prognosis factor (5-year disease-free survival rate: 83.8%), even with nuclear YAP1-positive expression (5-year disease-free survival rate: 83.7%), whereas nuclear YAP1-positive cases with the negative expression of CADM1 and LATS2 had a poorer prognosis (5-year disease-free survival rate: 33.3%). These results indicate that the relationship between CADM1 and Hippo pathway core kinases at the cell membrane is important for suppressing the oncogenic role of YAP1.

UDP-arabinopyranose mutase 3 is required for pollen wall morphogenesis in rice (Oryza sativa).

l-Arabinose is one of the main constituents of cell wall polysaccharides such as pectic rhamnogalacturonan I (RG-I), glucuronoarabinoxylans and other glycoproteins. It is found predominantly in the furanose form rather than in the thermodynamically more stable pyranose form. UDP-L-arabinofuranose (UDP-Araf), rather than UDP-L-arabinopyranose (UDP-Arap), is a sugar donor for the biosynthesis of arabinofuranosyl (Araf) residues. UDP-arabinopyranose mutases (UAMs) have been shown to interconvert UDP-Araf and UDP-Arap and are involved in the biosynthesis of polysaccharides including Araf. The UAM gene family has three members in Oryza sativa. Co-expression network in silico analysis showed that OsUAM3 expression was independent from OsUAM1 and OsUAM2 co-expression networks. OsUAM1 and OsUAM2 were expressed ubiquitously throughout plant development, but OsUAM3 was expressed primarily in reproductive tissue, particularly at the pollen cell wall formation developmental stage. OsUAM3 co-expression networks include pectin catabolic enzymes. To determine the function of OsUAMs in reproductive tissues, we analyzed RNA interference (RNAi)-knockdown transformants (OsUAM3-KD) specific for OsUAM3. OsUAM3-KD plants grew normally and showed abnormal phenotypes in reproductive tissues, especially in terms of the pollen cell wall and exine. In addition, we examined modifications of cell wall polysaccharides at the cellular level using antibodies against polysaccharides including Araf. Immunolocalization of arabinan using the LM6 antibody showed low levels of arabinan in OsUAM3-KD pollen grains. Our results suggest that the function of OsUAM3 is important for synthesis of arabinan side chains of RG-I and is required for reproductive developmental processes, especially the formation of the cell wall in pollen.

Maintenance of Methyl-Esterified Pectin Level in Pollen Mother-Cell Stages Is Required for Microspore Development.

Pectin modification and degradation are vital for plant development, although the underlying mechanisms are still not well understood. Furthermore, reports on the function of pectin in early pollen development are limited. We generated OsPME-FOX rice lines with little methyl-esterified pectin even in the early-pollen mother-cell stage due to overexpression of the gene encoding pectin-methylesterase. Overexpression of OsPME1 in rice increased the activity of PME, which decreased the degree of pectin methyl esterification in the cell wall. OsPME1-FOX grew normally and showed abnormal phenotypes in anther and pollen development, especially in terms of the pollen mother-cell stage. In addition, we examined modifications of cell-wall polysaccharides at the cellular level using antibodies against polysaccharides. Immunohistochemical staining using LM19 and LM20 showed that methyl-esterified pectin distribution and the pectin contents in pollen mother-cell wall decreased in OsPME1-FOX compared with the wild type. Thus, the maintenance of methyl-esterified pectin plays a role in degrading and maintaining the pollen mother-cell wall during microspore development.

Effect of silicon deficiency on secondary cell wall synthesis in rice leaf.

Rice (Oryza sativa L.) is a typical Si-accumulating plant and is able to accumulate Si up to >10 % of shoot dry weight. The cell wall has been reported to become thicker under Si-deficient condition. To clarify the relationship between Si accumulation and cell wall components, the physical properties of, and macromolecular components and Si content in, the pectic, hemicellulosic, and cellulosic fractions prepared from rice seedlings grown in hydroponics with or without 1.5 mM silicic acid were analyzed. In the absence of Si (the -Si condition), leaf blades drooped, but physical properties were enhanced. Sugar content in the cellulosic fraction and lignin content in the total cell wall increased under -Si condition. After histochemical staining, there was an increase in cellulose deposition in short cells and the cell layer just beneath the epidermis in the -Si condition, but no significant change in the pattern of lignin deposition. Expression of the genes involved in secondary cell wall synthesis, OsCesA4, OsCesA7, OsPAL, OsCCR1 and OsCAD6 was up-regulated under -Si condition, but expression of OsCesA1, involved in primary cell wall synthesis, did not increase. These results suggest that an increase in secondary cell wall components occurs in rice leaves to compensate for Si deficiency.

Effects of polygalacturonase overexpression on pectin distribution in the elongation zones of roots under aluminium stress.

The roots of many plant species contain large amounts of pectin and it contributes to the formation of the rhizosphere. In the present study, the relationship between the root-tip pectin content and aluminium (Al) tolerance in wild-type (WT) and demethylesterified pectin degradation enzyme gene overexpressor (OsPG2-FOX) rice lines was compared. OsPG2-FOX rice showed reduced pectin content in roots, even under control conditions; Al treatment reduced root elongation and the pectin content in the root elongation zone. Wild-type rice showed more pectin accumulation in the root elongation zone after Al treatment. Relative to WT rice, OsPG2-FOX rice showed more Al accumulation in the root elongation zone. These results indicate that the amount of pectin influences Al tolerance and that the distribution of pectin in the root elongation zone inhibits Al accumulation in rice roots. Pectin accumulation in cell walls in the root elongation zone may play a role in protecting rice plants from the Al-induced inhibition of root elongation by regulating pectin distribution.

Molecular and functional analyses of rice NHX-type Na+/H+ antiporter genes.

We previously cloned a vacuolar Na+/H+ antiporter gene (OsNHX1) from rice (Oryza sativa). Here we identified four additional NHX-type antiporter genes in rice (OsNHX2 through OsNHX5) and performed molecular and functional analyses of those genes. The exon-intron structure of the OsNHX genes and the phylogenetic tree of the OsNHX proteins suggest that the OsNHX proteins are categorized into two subgroups (OsNHX1 through OsNHX4 and OsNHX5). OsNHX1, OsNHX2, OsNHX3, and OsNHX5 can suppress the Na+, Li+, and hygromycin sensitivity of yeast nhx1 mutants and their sensitivity to a high K+ concentration. The expression of OsNHX1, OsNHX2, OsNHX3, and OsNHX5 is regulated differently in rice tissues and is increased by salt stress, hyperosmotic stress, and ABA. When we studied the expression of ß-glucuronidase (GUS) driven by either the OsNHX1 or the OsNHX5 promoter, we observed activity in the stele, the emerging part of lateral roots, the vascular bundle, the water pore, and the basal part of seedling shoots with both promoters. In addition, each promoter had a unique expression pattern. OsNHX1 promoter-GUS activity only was localized to the guard cells and trichome, whereas OsNHX5 promoter-GUS activity only was localized to the root tip and pollen grains. Our results suggest that the members of this gene family play important roles in the compartmentalization into vacuoles of the Na+ and K+ that accumulate in the cytoplasm and that the differential regulation of antiporter gene expression in different rice tissues may be an important factor determining salt tolerance in rice.

Pressure bandage as an effective treatment for intralymphatic histiocytosis associated with rheumatoid arthritis.

The patient is a 71-year-old male who has been suffering from rheumatoid arthritis for over 20 years. He first noticed the erythema on his right forearm in 2008, which got worse in 2009. Topical corticosteroids were not effective, and a skin biopsy was performed. Histopathologic examination showed aggregation of the inflammatory cells in the dermal vessels. Those cells were positive for CD68 and CD31 and all the surrounding vessels expressed D2-40 and CD31. We diagnosed him with intralymphatic histiocytosis. One week after the skin was biopsied, only the part of the erythematous lesion covered by skin tape had improved, suggesting that pressure on the lesion might improve the erythematous eruption. We therefore used a pressure bandage elbow supporter in addition to topical treatment. The lesion improved 3 months later and was totally diminished after 9 months. Combined with previously reported cases, our case suggested that intralymphatic histiocytosis is closely related to lymphostasis.

Rice Putative Methyltransferase Gene OsPMT16 Is Required for Pistil Development Involving Pectin Modification.

Pectin synthesis and modification are vital for plant development, although the underlying mechanisms are still not well understood. Furthermore, reports on the function of pectin in the pistil are limited. Herein, we report the functional characterization of the OsPMT16 gene, which encodes a putative pectin methyltransferase (PMT) in rice. The cell walls of rice leaves contain less pectin, and chemical analysis of pectin in the flower organ had not been previously performed. Therefore, in the present study, the amount of pectin in the reproductive tissues of rice was investigated. Of the reproductive tissues, the pistil was especially rich in pectin; thus, we focused on the pistil. OsPMT16 expression was confirmed in the pistil, and effects of pectin methylesterification regulation on the reproductive stage were investigated by studying the phenotype of the T-DNA insertion mutant. The ospmt16 mutant showed significantly reduced fertility. When the flowers were observed, tissue morphogenesis was abnormal in the pistil. Immunofluorescence staining by pectin-specific monoclonal antibodies of the pistil revealed that total pectin and esterified pectin were decreased among ospmt16 mutants. These results indicate that OsPMT16 contributes significantly to pistil development during reproductive growth.

Changes in the Distribution of Pectin in Root Border Cells Under Aluminum Stress.

Root border cells (RBCs) surround the root apices in most plant species and are involved in the production of root exudates. We tested the relationship between pectin content in root tips and aluminum (Al) tolerance by comparing these parameters in wild-type (WT) and sensitive-to-Al-rhizotoxicity (star1) mutant rice plants. Staining for demethylesterified pectin decreased after Al treatment in the WT. A high level of pectin was observed in RBCs of the root tips. The level of total pectin was increased by about 50% compared with the control. In the Al-sensitive star1 mutant, Al treatment decreased root elongation and pectin content, especially in RBCs. In addition, almost no Al accumulation was observed in the control, whereas more Al was accumulated in the RBCs of STAR1 roots. These results show that the amount of pectin influences Al tolerance; that Al accumulation in rice roots is reduced by the distribution of pectin in root-tip RBCs; and that these reactions occur in the field around the RBCs, including the surrounding mucilage. Al accumulation in rice roots is reduced by the distribution of pectin in root tips, and pectin in the root cell walls contributes to the acquisition of Al tolerance in rice by regulating its distribution. The release of Al-binding mucilage by RBCs could play a role in protecting root tips from Al-induced cellular damage.

Nuclear localization of the 20S proteasome subunit in Parkinson's disease.

Considering the involvement of ubiquitin-proteasome system (UPS) in Parkinson's disease (PD), the aim of the present study was to determine the distribution of proteasomes in PD brains. Immunohistochemical studies showed localization of 20S proteasome in the nuclei of neurons of the putamen and substantia nigra of PD. In contrast, no nuclear staining was observed in the same areas of brains of controls. Our results suggest that nuclear localization of 20S proteasome seems to be associated with the pathogenesis of PD.

Identification of a new G-to-A transition mutation at nucleotide position 129 of the Xrcc4 gene in ionizing radiation-hypersensitive mutant LX830 cells.

The mouse lymphoma cell line LX830 is an X-ray-hypersensitive mutant. Complementation tests between LX830 cells and radiation-sensitive mutants of M10 (Xrcc4 deficient cells) or SX10 (DNA ligase IV deficient cells) cells showed that M10 cells did not complement LX830 cells, but SX10 cells did, suggesting that LX830 cells would belong to the X-ray-cross complementation group (XRCC4). A sequence analysis of Xrcc4 cDNA in LX830 cells disclosed a transition of G to A at nucleotide position 129, which resulted in a change of tryptophan (43) to a termination codon. Transfection of the mouse Xrcc4 cDNA rescued the X-ray sensitivity of the mutant cells. LX830 is an Xrcc4-deficient cell line bearing a termination codon in exon 2 of the Xrcc4 gene and no wild-type Xrcc4 gene.

A case of lichen planus pemphigoides successfully treated with a combination of cyclosporine a and prednisolone.

Lichen planus pemphigoides (LPP) is a rare clinical variant of bullous pemphigoid (BP). A 35-year-old female patient presented to our hospital complaining of pruritic violaceous-colored plaques or papules on the extremities. Tense vesicles were also seen on the soles. Skin biopsies from the papules and vesicles demonstrated lichen planus and BP, respectively. Direct immunofluorescence demonstrated linear IgG and C3 deposition on the basement membrane zone. Indirect immunofluorescence on 1 M NaCl split skin detected IgG reactivity with the epidermal side. Enzyme-linked immunosorbent assay also detected anti-BP180 antibodies. After treatment with oral prednisolone alone had failed, low-dose cyclosporine A (CyA) was added. The clinical symptoms immediately improved and the titer of the anti-BP180 antibodies decreased. Although there is little information about the treatment of recalcitrant LPP, additional CyA appeared to be beneficial.

Acquired expression of NFATc1 downregulates E-cadherin and promotes cancer cell invasion.

NFATc1 is a transcription factor that regulates T-cell development, osteoclastogenesis, and macrophage function. Given that T cells, osteoclasts, and macrophages in the tumor microenvironment are thought to modulate tumor progression, tumor cells may acquire NFATc1 expression through fusion with these NFATc1-expressing normal cells. We here revealed that a small proportion of tumor cells in human carcinoma specimens expressed NFATc1. To investigate the consequences of NFATc1 acquisition by tumor cells, we established A549 and MCF7 cell lines expressing a constitutively active form of NFATc1 (NFATc1CA) in an inducible manner. The expression of NFATc1CA promoted cancer cell invasion in association with changes in cell morphology. Analysis of gene expression and RNA interference experiments revealed that NFATc1CA suppressed E-cadherin expression by upregulating the transcriptional repressors Snail and Zeb1 in a manner independent of TGF-ß signaling. Induced expression of NFATc1CA also downregulated E-cadherin expression and increased invasive activity in tumor xenografts in vivo. Our results thus suggest that the acquisition of NFATc1 expression contributes to tumor progression.

Increase in cellulose accumulation and improvement of saccharification by overexpression of arabinofuranosidase in rice.

Cellulosic biomass is available for the production of biofuel, with saccharification of the cell wall being a key process. We investigated whether alteration of arabinoxylan, a major hemicellulose in monocots, causes an increase in saccharification efficiency. Arabinoxylans have ß-1,4-D-xylopyranosyl backbones and 1,3- or 1,4-α-l-arabinofuranosyl residues linked to O-2 and/or O-3 of xylopyranosyl residues as side chains. Arabinose side chains interrupt the hydrogen bond between arabinoxylan and cellulose and carry an ester-linked feruloyl substituent. Arabinose side chains are the base point for diferuloyl cross-links and lignification. We analyzed rice plants overexpressing arabinofuranosidase (ARAF) to study the role of arabinose residues in the cell wall and their effects on saccharification. Arabinose content in the cell wall of transgenic rice plants overexpressing individual ARAF full-length cDNA (OsARAF1-FOX and OsARAF3-FOX) decreased 25% and 20% compared to the control and the amount of glucose increased by 28.2% and 34.2%, respectively. We studied modifications of cell wall polysaccharides at the cellular level by comparing histochemical cellulose staining patterns and immunolocalization patterns using antibodies raised against α-(1,5)-linked l-Ara (LM6) and ß-(1,4)-linked d-Xyl (LM10 and LM11) residues. However, they showed no visible phenotype. Our results suggest that the balance between arabinoxylan and cellulose might maintain the cell wall network. Moreover, ARAF overexpression in rice effectively leads to an increase in cellulose accumulation and saccharification efficiency, which can be used to produce bioethanol.

Rice shaker potassium channel OsKAT1 confers tolerance to salinity stress on yeast and rice cells.

We screened a rice (Oryza sativa L. 'Nipponbare') full-length cDNA expression library through functional complementation in yeast (Saccharomyces cerevisiae) to find novel cation transporters involved in salt tolerance. We found that expression of a cDNA clone, encoding the rice homolog of Shaker family K(+) channel KAT1 (OsKAT1), suppressed the salt-sensitive phenotype of yeast strain G19 (Deltaena1-4), which lacks a major component of Na(+) efflux. It also suppressed a K(+)-transport-defective phenotype of yeast strain CY162 (Deltatrk1Deltatrk2), suggesting the enhancement of K(+) uptake by OsKAT1. By the expression of OsKAT1, the K(+) contents of salt-stressed G19 cells increased during the exponential growth phase. At the linear phase, however, OsKAT1-expressing G19 cells accumulated less Na(+) than nonexpressing cells, but almost the same K(+). The cellular Na(+) to K(+) ratio of OsKAT1-expressing G19 cells remained lower than nonexpressing cells under saline conditions. Rice cells overexpressing OsKAT1 also showed enhanced salt tolerance and increased cellular K(+) content. These functions of OsKAT1 are likely to be common among Shaker K(+) channels because OsAKT1 and Arabidopsis (Arabidopsis thaliana) KAT1 were able to complement the salt-sensitive phenotype of G19 as well as OsKAT1. The expression of OsKAT1 was restricted to internodes and rachides of wild-type rice, whereas other Shaker family genes were expressed in various organs. These results suggest that OsKAT1 is involved in salt tolerance of rice in cooperation with other K(+) channels by participating in maintenance of cytosolic cation homeostasis during salt stress and thus protects cells from Na(+).

Molecular cloning, functional expression and subcellular localization of two putative vacuolar voltage-gated chloride channels in rice (Oryza sativa L.).

We isolated two cDNA clones (OsCLC-1 and OsCLC-2) homologous to tobacco CLC-Nt1, which encodes a voltage-gated chloride channel, from rice (Oryza sativa L. ssp. japonica, cv. Nipponbare). The deduced amino acid sequences were highly conserved (87.9% identity with each other). Southern blot analysis of the rice genomic DNA revealed that OsCLC-1 and OsCLC-2 were single-copy genes on chromosomes 4 and 2, respectively. OsCLC-1 was expressed in most tissues, whereas OsCLC-2 was expressed only in the roots, nodes, internodes and leaf sheaths. The level of expression of OsCLC-1, but not of OsCLC-2, was increased by treatment with NaCl. Both genes could partly substitute for GEF1, which encodes the sole chloride channel in yeast, by restoring growth under ionic stress. These results indicate that both genes are chloride channel genes. The proteins from both genes were immunochemically detected in the tonoplast fraction. Tagged synthetic green fluorescent protein which was fused to OsCLC-1 or OsCLC-2 localized in the vacuolar membranes. These results indicate that the proteins may play a role in the transport of chloride ions across the vacuolar membrane. We isolated loss-of-function mutants of both genes from a panel of rice mutants produced by the insertion of a retrotransposon, Tos17, in the exon region, and found inhibition of growth at all life stages.

Effect of salt and osmotic stresses on the expression of genes for the vacuolar H+-pyrophosphatase, H+-ATPase subunit A, and Na+/H+ antiporter from barley.

Two cDNA clones encoding vacuolar H+-inorganic pyrophosphatase (HVP1 and HVP10), one clone encoding the catalytic subunit (68 kDa) of vacuolar H+-ATPase (HvVHA-A), and one clone encoding vacuolar Na+/H+ antiporter (HvNHX1) were isolated from barley (Hordeum vulgare), a salt-tolerant crop. Salt stress increased the transcript levels of HVP1, HVP10, HvVHA-A, and HvNHX1, and osmotic stress also increased the transcript levels of HVP1 and HvNHX1 in barley roots. The transcription of HVP1 in response to salt stress was regulated differently from that of HVP10. In addition, the HVP1 expression changed in a pattern similar to that of HvNHX1 expression. These results indicate that the expression of HVP1 is co-ordinated with that of HvNHX1 in barley roots in response to salt and osmotic stresses.