Search PubMed⌕ Search

Biomedical subjects

Ken Matsuoka

Publications and source records attributed to Ken Matsuoka.

13 recordsLinked to original sources
PubMed2006

Characterization of NtChitIV, a class IV chitinase induced by beta-1,3-, 1,6-glucan elicitor from Alternaria alternata 102: Antagonistic effect of salicylic acid and methyl jasmonate on the induction of NtChitIV.

Tobacco BY-2 class IV chitinases (TBC-1, TBC-3) were rapidly and transiently induced by the beta-1,3-, 1,6-glucan elicitor from Alternaria alternata 102 (AaGlucan). The full-length cDNA and 5'-flanking region of a gene encoding class IV chitinases were isolated on the basis of the amino acid sequence of TBC-1. Sequence analysis indicated that NtChitIV encoded TBC-1, TBC-3, or both. Since purified TBC-1 and TBC-3 from BY-2 cells lack a chitin binding domain in the N-terminal region, these enzymes suggested to be derived from NtChitIV by post-translational proteolytic processing. The transcripts of NtChitIV accumulated rapidly within 1h after treatment with AaGlucan. Accumulation was maximal 3h after treatment. Reporter gene assays were used to analyze the promoter regions involved in the transcriptional control of NtChitIV, and these assays revealed that the 1.89-kb NtChitIV promoter was activated by AaGlucan but not by salicylic acid (SA) or methyl jasmonate (MeJA). The AaGlucan-induced transcriptional activation via 1.89-kb NtChitIV promoter was attenuated by pretreatment with SA or MeJA. These results suggest that NtChitIV expression is particularly induced by AaGlucan and that the AaGlucan-dependent signaling pathway is different from the SA- and MeJA-dependent signaling pathways.

Acetates↗
PubMed2006

Expression and Ca2+ dependency of plasma membrane K+ channels of tobacco suspension cells adapted to salt stress.

The expression of plasma membrane K+ channels of NaCl-adapted tobacco suspension cells and effects of extracellular Ca2+ on plasma membrane K+ channels were investigated. Reverse transcription-PCR (RT-PCR) analysis showed that expression of TORK1, which encodes a K+ channel, was much lower in NaCl-adapted cells than in NaCl-unadapted cells. The magnitude of the outward K+ currents of NaCl-adapted as well as NaCl-unadapted cells decreased with increasing extracellular Ca2+ but there is no significant difference in Ca2+ dependency of the K+ current. These analyses suggest that reduction of the number of K+ channels might cause NaCl adaptation of cells through the decrease of outward K+ currents.

Adaptation, Physiological↗
PubMed2006

Protein aggregates are transported to vacuoles by a macroautophagic mechanism in nutrient-starved plant cells.

When a fusion protein of cytochrome b5 (Cyt b5) and the red fluorescent protein (RFP) are expressed in tobacco BY-2 cells, the expressed protein forms intracellular aggregates that emit red fluorescence. When such cells are grown to the stationary phase or incubated in nutrient limited medium, RFP fluorescence can be detected in the vacuolar lumen. We investigated this transport mechanism using a limited-nitrogen model. E-64 and 3-methyladenine, which inhibit autophagic processes, blocked the transport of the RFP signal to the vacuole. We next traced the autophagic process in tobacco cells using YFP fused with the tobacco Atg8 homologue (YFP-NtAtg8) and analyzed the contribution of autophagy to the vacuolar transport of the aggregates. Under limited-nitrogen conditions, the aggregates were degraded in preference to other organelles, and the autophagosomes colocalized with the aggregates at a higher frequency than with mitochondria. This is the first demonstration that selective macroautophagic degradation can occur in plant cells.

Adenine↗
PubMed2006

Genetic and functional interaction between Ryh1 and Ypt3: two Rab GTPases that function in S. pombe secretory pathway.

We have previously isolated ypt3-i5 mutant and showed that Ypt3 GTPase functions in the fission yeast secretory pathway. Here, the same genetic screen led to the isolation of ryh1-i6, a mutant allele of the ryh1+ gene encoding a homolog of Rab6. The ryh1-i6 mutant showed phenotypes that support its role in retrograde traffic from endosome to the Golgi. Interestingly, ryh1+ gene deletion was synthetically lethal with ypt3-i5 mutation. Consistently, the over-expression of the GDP-conformational mutant, Ryh1T25 N, inhibited the growth of ypt3-i5 mutant but had no effect on that of wild-type cells. Furthermore, the over-expression of the Ryh1T25N mutant inhibited the acid phosphatase glycosylation and exacerbated the cell wall integrity of ypt3-i5 mutant, but had no effect on those of wild-type cells. GFP-Ryh1 and GFP-Ypt3 both localized at the Golgi/endosome, but showed distinct subcellular localizations. The localization of GFP-Ryh1 in ypt3-i5 mutant and that of GFP-Ypt3 in ryh1-i6 mutant were distinct from those in wild-type cells. In addition, Ryh1 as well as Ypt3 were shown to be involved in acid phosphatase secretion. These results suggest that Ryh1 is involved in the secretory pathway and may have a potential overlapping function with Ypt3 in addition to its role in recycling.

Acid Phosphatase↗
PubMed2006

A novel R2R3 MYB transcription factor NtMYBJS1 is a methyl jasmonate-dependent regulator of phenylpropanoid-conjugate biosynthesis in tobacco.

Target metabolic and large-scale transcriptomic analyses of tobacco (Nicotiana tabacum L.) Bright Yellow-2 (BY-2) cells were employed to identify novel gene(s) involved in methyl jasmonate (MJ)-dependent function in plants. At the metabolic level, we describe the specific accumulation of several phenylpropanoid-polyamine conjugates in MJ-treated BY-2 cells. Furthermore, global gene expression analysis of MJ-treated cells using a 16K cDNA microarray containing expressed sequence tags (ESTs) from BY-2 cells revealed 828 genes that were upregulated by MJ treatment within 48 h. Using time-course expression data we identified a novel MJ-inducible R2R3 MYB-type transcription factor (NtMYBJS1) that was co-expressed in a close temporal pattern with the core phenylpropanoid genes phenylalanine ammonia-lyase (PAL) and 4-coumarate:CoA ligase (4CL). Overexpression of NtMYBJS1 in tobacco BY-2 cells caused accumulation of specific phenylpropanoid conjugates in the cells. Subsequent microarray analysis of NtMYBJS1 transgenic lines revealed that a limited number of genes, including PAL and 4CL, were specifically induced in the presence of the NtMYBJS1 transgene. These results, together with results of both antisense expression analysis and of gel mobility shift assays, strongly indicate that the NtMYBJS1 protein functions in tobacco MJ signal transduction, inducing phenylpropanoid biosynthetic genes and the accumulation of phenylpropanoid-polyamine conjugates during stress.

Acetates↗
PubMed2006

Novel beta-1,3-, 1,6-oligoglucan elicitor from Alternaria alternata 102 for defense responses in tobacco.

A novel elicitor that induces chitinases in tobacco BY-2 cells was isolated from Alternaria alternata 102. Six other fungi, including A. alternata IFO 6587, could not induce, or weakly induce chitinase activity. The purified elicitor was soluble in 75% methanol and showed the chitinase-inducing activity when applied at concentrations of as low as 25 ng x mL(-1). Structural determination by methylation analysis, reducing-end analysis, MALDI-TOF/MS, and NMR spectroscopy indicated that the elicitor was a mixture of beta-1,3-, 1,6-oligoglucans mostly with a degree of polymerization of between 8 and 17. Periodate oxidation of the elicitor suggested that the 1,6-linked and nonreducing terminal residues are essential for the elicitor activity. Further analysis of the elicitor responses in BY-2 cells indicated that the activity of this beta-1,3-, 1,6-glucan elicitor was about 1000 times more potent than that of laminarin, which is a known elicitor of defense responses in tobacco. Analyzing the expression of defense-related genes indicated that a phenylalanine ammonia-lyase gene and a coumaroyl-CoA O-methyltransferase gene were transiently expressed by this beta-1,3-, 1,6-glucan elicitor. The elicitor induced a weak oxidative burst but did not induce cell death in the BY-2 cells. In the tissue of tobacco plants, this beta-1,3-, 1,6-glucan elicitor induced the expression of basic PR-3 genes, the phenylpropanoid pathway genes, and the sesquiterpenoid pathway genes. In comparison with laminarin and laminarin sulfate, which are reported to be potent elicitors of defense responses in tobacco, the expression pattern of genes induced by the purified beta-1,3-, 1,6-glucan elicitor was more similar to that induced by laminarin than to that induced by laminarin sulfate.

Alternaria↗
PubMed2005

Analysis of expressed sequence tags in prothallia of Adiantum capillus-veneris.

The analysis of expressed sequences from a diverse set of plant species has fueled the increase in understanding of the complex molecular mechanisms underlying plant growth regulation. While representative data sets can be found for the major branches of plant evolution, fern species data are lacking. To further the availability of genetic information in pteridophytes, a normalized cDNA library of Adiantum capillus-veneris was constructed from prothallia grown under white light. A total of 10,420 expressed sequence tags (ESTs) were obtained and clustering of these sequences resulted in 7,100 nonredundant clusters. Of these, 1,608 EST clusters were found to be similar to sequences of known function and 1,092 EST clusters showed similarity to sequences of unknown function. Given the usefulness of Adiantum for developmental studies, the sequence data represented in this report stand to make a significant contribution to the understanding of plant growth regulation, particularly for pteridophytes.

Adiantum↗
PubMed2005

TONSOKU is expressed in S phase of the cell cycle and its defect delays cell cycle progression in Arabidopsis.

TONSOKU(TSK)/MGOUN3/BRUSHY1 of Arabidopsis thaliana encodes a nuclear leucine-glycine-aspargine (LGN) domain protein implicated to be involved in genome maintenance, and mutants with defects in TSK show a fasciated stem with disorganized meristem structures. We identified a homolog of TSK from tobacco BY-2 cells (NtTSK), which showed high sequence conservation both in the LGN domain and in leucine-rich repeats with AtTSK. The NtTSK gene was expressed during S phase of the cell cycle in tobacco BY-2 cells highly synchronized for cell division. The tsk mutants of Arabidopsis contained an increased proportion of cells with 4C nuclei and cells expressing cyclin B1 compared with the wild type. These results suggest that TSK is required during the cell cycle and defects of TSK cause the arrest of cell cycle progression at G2/M phase.

Amino Acid Sequence↗
PubMed2005

Membrane-anchored prolyl hydroxylase with an export signal from the endoplasmic reticulum.

We cloned a novel prolyl 4-hydroxylase (PH; EC 1.14.11.2) homolog cDNA from tobacco (Nicotiana tabacum) BY-2 cells based on expression sequence tag information. Like other PHs, this tobacco PH polypeptide has two conserved histidine residues, and it comprises 286 amino acids with a calculated molecular mass of 32 kDa. Interestingly, this protein and homologs in Arabidopsis and rice have predicted transmembrane sequences in their N-terminal regions. This PH homolog was expressed in BY-2 cells as a His-tagged protein, and the expressed protein showed PH activity. Incubation of membranes with high salt, urea, and protease with or without detergents indicated that this protein is an integral membrane protein with a type II configuration. Its membrane-anchored nature is specific for plants because no integral membrane PH has been found in animals. A membrane fractionation study and immunocytochemical studies indicate that this protein localizes in both the endoplasmic reticulum (ER) and Golgi apparatus. Analysis of this protein fused to green fluorescent protein indicated that basic amino acids in the cytoplasmic, N-terminal region of the PH play a role in its export from the ER.

Amino Acid Sequence↗
PubMed2005

Experimental determination of proline hydroxylation and hydroxyproline arabinogalactosylation motifs in secretory proteins.

Many secretory and several vacuolar proteins in higher plants contain hydroxylated proline residues. In many cases, hydroxyprolines in proteins are glycosylated with either arabinogalactan or oligoarabinose. We have previously shown that a sporamin precursor is O-glycosylated at the hydroxylated proline 36 residue with an arabinogalactan-type glycan when this protein is expressed in tobacco BY-2 cells (Matsuoka et al., 1995). Taking advantage of the fact that this is the only site of proline hydroxylation and glycosylation in sporamin, we analyzed the amino acid requirement for proline hydroxylation and arabinogalactosylation. We expressed several deletion constructs and many amino acid substitution mutants in tobacco cells and analyzed glycosylation and proline hydroxylation of the expressed sporamins. Hydroxylation of a proline residue requires the five amino acid sequence [AVSTG]-Pro-[AVSTGA]-[GAVPSTC]-[APS or acidic] (where Pro is the modification site) and glycosylation of hydroxyproline (Hyp) requires the seven amino acid sequence [not basic]-[not T]-[neither P, T, nor amide]-Hyp-[neither amide nor P]-[not amide]-[APST], although charged amino acids at the -2 position and basic amide residues at the +1 position relative to the modification site seem to inhibit the elongation of the arabinogalactan side chain. Based on the combination of these two requirements, we concluded that the sequence motif for efficient arabinogalactosylation, including the elongation of the glycan side chain, is [not basic]-[not T]-[AVSG]-Pro-[AVST]-[GAVPSTC]-[APS].

Amino Acid Motifs↗
PubMed2004

3-methyladenine inhibits autophagy in tobacco culture cells under sucrose starvation conditions.

Tobacco (Nicotiana tabacum) culture cells perform autophagy and degrade cellular proteins in response to sucrose starvation. When protein degradation is blocked by the cysteine protease inhibitor E-64c, lysosomes containing particles of cytoplasm (autolysosomes) accumulate in the cells. Therefore, using light microscopy, we can determine whether cells have performed autophagy. In this study, we investigated whether or not 3-methyladenine (3-MA), which is a known inhibitor of autophagy in mammalian cells, blocks autophagy in tobacco culture cells. The accumulation of autolysosomes was blocked by the addition to the culture media of 5 mM 3-MA together with E-64c. We did not detect autolysosomes or structures thought to be involved with autophagy, such as autophagosomes, accumulating in these cells, as observed by electron microscopy. 3-MA blocked cellular protein degradation without any effect on cellular protease activity. In mammalian cells, phosphatidylinositol 3-kinase (PtdIns 3-kinase) is a putative target of 3-MA. The PtdIns 3-kinase inhibitors wortmannin and LY294002 also inhibited the accumulation of autolysosomes in tobacco culture cells. These results suggest that (1) 3-MA inhibits autophagy by blocking the formation of autophagosomes in tobacco culture cells, and (2) PtdIns 3-kinase is essential for autophagy in tobacco cells.

Adenine↗
PubMed2004

A comprehensive gene expression analysis toward the understanding of growth and differentiation of tobacco BY-2 cells.

To understand how plant cell changes gene expression during cell division and after termination of cell division, we analyzed the change of gene expression during the growth of tobacco BY-2 cell lines using a cDNA microarray, which contained about 9,200 expression sequence tag fragments and corresponded to about 7,000 genes. We found that log phase cells predominantly expressed DNA/chromosome duplication gene homologs. In addition, many genes for basic transcription and translation machineries, as well as proteasomal genes, were up-regulated at the log phase. About half of the kinesin homolog genes, but not myosin homolog genes, were predominantly expressed at the dividing phase as well. In contrast, stationary phase cells expressed genes for many receptor kinases, signal transduction machineries and transcription factors. Several hundreds of genes showed differential expression after incubation of stationary phase cells with medium containing either salicylic acid or abscisic acid. These findings suggested that BY-2 cells at the stationary phase express genes for perceiving extracellular signals.

Base Sequence↗