Gut bacteria identified in colorectal cancer patients promote tumourigenesis via butyrate secretion.

Emerging evidence is revealing that alterations in gut microbiota are associated with colorectal cancer (CRC). However, very little is currently known about whether and how gut microbiota alterations are causally associated with CRC development. Here we show that 12 faecal bacterial taxa are enriched in CRC patients in two independent cohort studies. Among them, 2 Porphyromonas species are capable of inducing cellular senescence, an oncogenic stress response, through the secretion of the bacterial metabolite, butyrate. Notably, the invasion of these bacteria is observed in the CRC tissues, coinciding with the elevation of butyrate levels and signs of senescence-associated inflammatory phenotypes. Moreover, although the administration of these bacteria into ApcΔ14/+ mice accelerate the onset of colorectal tumours, this is not the case when bacterial butyrate-synthesis genes are disrupted. These results suggest a causal relationship between Porphyromonas species overgrowth and colorectal tumourigenesis which may be due to butyrate-induced senescence.

A BET family protein degrader provokes senolysis by targeting NHEJ and autophagy in senescent cells.

Although cellular senescence acts primarily as a tumour suppression mechanism, the accumulation of senescent cells in vivo eventually exerts deleterious side effects through inflammatory/tumour-promoting factor secretion. Thus, the development of new drugs that cause the specific elimination of senescent cells, termed senolysis, is anticipated. Here, by an unbiased high-throughput screening of chemical compounds and a bio-functional analysis, we identify BET family protein degrader (BETd) as a promising senolytic drug. BETd provokes senolysis through two independent but integrated pathways; the attenuation of non-homologous end joining (NHEJ), and the up-regulation of autophagic gene expression. BETd treatment eliminates senescent hepatic stellate cells in obese mouse livers, accompanied by the reduction of liver cancer development. Furthermore, the elimination of chemotherapy-induced senescent cells by BETd increases the efficacy of chemotherapy against xenograft tumours in immunocompromised mice. These results reveal the vulnerability of senescent cells and open up possibilities for its control.

Chloramphenicol inhibits eukaryotic Ser/Thr phosphatase and infection-specific cell differentiation in the rice blast fungus.

Chloramphenicol (Cm) is a broad-spectrum classic antibiotic active against prokaryotic organisms. However, Cm has severe side effects in eukaryotes of which the cause remains unknown. The plant pathogenic fungus Magnaporthe oryzae, which causes rice blast, forms an appressorium to infect the host cell via single-cell differentiation. Chloramphenicol specifically inhibits appressorium formation, which indicates that Cm has a novel molecular target (or targets) in the rice blast fungus. Application of the T7 phage display method inferred that MoDullard, a Ser/Thr-protein phosphatase, may be a target of Cm. In animals Dullard functions in cell differentiation and protein synthesis, but in fungi its role is poorly understood. In vivo and in vitro analyses showed that MoDullard is required for appressorium formation, and that Cm can bind to and inhibit MoDullard function. Given that human phosphatase CTDSP1 complemented the MoDullard function during appressorium formation by M. oryzae, CTDSP1 may be a novel molecular target of Cm in eukaryotes.

Chitin-deacetylase activity induces appressorium differentiation in the rice blast fungus Magnaporthe oryzae.

The rice blast fungus Magnaporthe oryzae differentiates a specialized infection structure called an appressorium to invade rice cells. In this report, we show that CBP1, which encodes a chitin-deacetylase, is involved in the induction phase of appressorium differentiation. We demonstrate that the enzymatic activity of Cbp1 is critical for appressorium formation. M. oryzae has six CDA homologues in addition to Cbp1, but none of these are indispensable for appressorium formation. We observed chitosan localization at the fungal cell wall using OGA488. This observation suggests that Cbp1-catalysed conversion of chitin into chitosan occurs at the cell wall of germ tubes during appressorium differentiation by M. oryzae. Taken together, our results provide evidence that the chitin deacetylase activity of Cbp1 is necessary for appressorium formation.

Suppression of elongation and growth of tomato seedlings by auxin biosynthesis inhibitors and modeling of the growth and environmental response.

To develop a growth inhibitor, the effects of auxin inhibitors were investigated. Application of 30 µM L-α-aminooxy-ß-phenylpropionic acid (AOPP) or (S)-methyl 2-((1,3-dioxoisoindolin-2-yl)oxy)-3-phenylpropanoate (KOK1101), decreased the endogenous IAA levels in tomato seedlings at 8 days after sowing. Then, 10-1200 µM AOPP or KOK1101 were sprayed on the leaves and stem of 2-3 leaf stage tomato plants grown under a range of environmental conditions. We predicted plant growth and environmental response using a model based on the observed suppression of leaf enlargement. Spraying AOPP or KOK1101 decreased stem length and leaf area. Concentration-dependent inhibitions and dose response curves were observed. Although the effects of the inhibitors on dry weight varied according to the environmental conditions, the net assimilation rate was not influenced by the inhibitors. Accordingly, the observed decrease in dry weight caused by the inhibitors may result from decreased leaf area. Validation of the model based on observed data independent of the dataset showed good correlations between the observed and predicted values of dry weight and leaf area index.

A eukaryotic molecular target candidate of roxithromycin: fungal differentiation as a sensitive drug target analysis system.

Roxithromycin (RXM), active against prokaryotes, has beneficial side effects such as anti-cancer activities on mammalian cells, but the mechanisms underlying these effects remain unclear. We found that RXM inhibited the cellular differentiation of the rice blast fungus Magnaporthe oryzae. Hence, we screened the targets of RXM by the T7 phage display method with fungal genomic DNA, and identified MoCDC27 (M. oryzae Cell Division Cycle 27) as a candidate. We generated mocdc27 knockdown mutants that the appressoria formation was less affected by RXM. A complemented mutant restored sensitivity against RXM to the level of the wild type. These results suggest that MoCDC27 was involved in the inhibition of appressorium formation by RXM, and that the complex of RXM-MoCDC27 affected another molecule involved in appressorium formation. The T7 phage display method with fungal genomic DNA can be a useful tool in the quest for drug target.

Light-induced root hair formation in lettuce (Lactuca sativa L. cv. Grand Rapids) roots at low pH is brought by chlorogenic acid synthesis and sugar.

Previously, we reported that chlorogenic acid (CGA) facilitated root hair formation at pH 4.0 in lettuce (Lactuca sativa L. cv. Grand Rapids). Light was essential for this process. In the present study, we determined relationships between CGA, light, and sugar during root hair formation in lettuce seedlings. The amount of CGA increased with white light in intact seedlings. Exogenously applied CGA restored root hair formation in dark-grown intact seedlings at pH 4.0. However, no root hair formation was induced in decapitated seedlings regardless of light exposure and CGA application. Application of sucrose or glucose induced both root hair formation and CGA synthesis in light-grown decapitated seedlings at pH 4.0. Blue light was the most effective for both root hair formation and CGA synthesis when supplied with sucrose to decapitated seedlings. Addition of sucrose and CGA together induced root hair formation at pH 4.0 in dark-grown decapitated seedlings. Results suggest that light induced CGA synthesis from sugar in the roots. Sugar was also required for root hair formation other than starting material of CGA synthesis. In addition, an unknown low pH-induced factor was essential for lettuce root hair formation.

Chlorogenic acid facilitates root hair formation in lettuce seedlings.

Root hairs, which arise from root epidermal cells, are tubular structures that increase the efficiency of water absorption and nutrient uptake. A low pH (pH 4) medium induced root hair formation in lettuce (Lactuca sativa L.) seedlings, and the decapitation of shoots inhibited root hair formation. The addition of shoot extract to the medium restored root hair formation in the decapitated lettuce seedlings. These results suggest that factors essential to the formation of root hairs may be present in the shoot. We purified one factor from the shoot that facilitates root hair formation. This factor was identified as chlorogenic acid (CGA), a common polyphenol in higher plants. The presence of exogenous CGA in the medium induced root hair formation in decapitated lettuce seedlings at pH 4.0 and in intact lettuce seedlings at pH 6.0. The optimum concentration of CGA for root hair formation was identified as 10(-5) M. Decapitation of the shoots reduced the CGA content in the roots to approximately one-third that in intact plants. Application of the CGA biosynthesis inhibitor L-alpha-aminooxy-beta-phenylpropionic acid (AOPP, 10(-6) M) to intact seedlings grown at pH 4.0 reduced both the CGA content of the roots and the total amount of root hairs. The addition of exogenous CGA restored root hair formation in intact seedlings treated with AOPP. These results suggest that CGA is essential for root hair formation in lettuce seedlings.