Project description:Marine brown algae produce the highly recalcitrant polysaccharide fucoidan, contributing to long-term oceanic carbon storage and climate regulation. Fucoidan is degraded by specialized heterotrophic bacteria, which promote ecosystem function and global carbon turnover using largely uncharacterized mechanisms. Here, we isolate and study two Planctomycetota strains from the microbiome associated with the alga Fucus spiralis, which grow efficiently on chemically diverse fucoidans. One of the strains appears to internalize the polymer, while the other strain degrades it extracellularly. Multi-omic approaches show that fucoidan breakdown is mediated by the expression of divergent polysaccharide utilization loci, and endo-fucanases of family GH168 are strongly upregulated during fucoidan digestion. Enzymatic assays and structural biology studies reveal how GH168 endo-fucanases degrade various fucoidan cores from brown algae, assisted by auxiliary hydrolytic enzymes. Overall, our results provide insights into fucoidan processing mechanisms in macroalgal-associated bacteria.
Project description:Fucoidan is a high-molecular polysaccharide whose main constituent is sulfated fucose. Extensive studies have demonstrated numerous interesting biological activities for fucoidan. We specifically focused on the anti-proliferation activity of fucoidan and examined the underlying mechanism in MKN45 gastric cancer cells. BrdU assay revealed that fucoidan impeded the MKN45 cell cycle by approximately 50%, and clonogenic assay also showed that fucoidan inhibited cell proliferation. Preliminary examinations of fucoidan using LDH assay showed no immediate cytotoxic effects at 24-h exposure. However, longer time courses revealed inhibition of cell growth at 4 days in a dose-dependent manner. Microarray analysis in MKN45 cells treated with fucoidan identified genes that were upregulated and downregulated in response to fucoidan, including MAP3K5, or ASK1 (apoptosis signal-regulating kinase), which was upregulated by 1.38-fold. Western blot confirmed that fucoidan increased ASK1 protein levels, while reducing the levels of phosphorylated ASK1. Reduction of ASK1 by siRNA decreased proliferation of MKN45 cells. Our findings show that fucoidan may suppress cellular proliferation and DNA synthesis in MKN45 cells by suppressing the ASK1-p38 signaling pathway through reduction of phosphorylated ASK1 levels.
Project description:Oligo-fucoidan (OF), a sulfated polysaccharide extracted from brown seaweed, exhibits anti-inflammation and antitumor effects, however, knowledge concerning the detailed mechanism of oligo-fucoidan on liver cells is obscure. In this study, we investigate the effect of oligo-fucoidan in normal hepatocytes using transcriptomic analysis. Using an oligo-fucoidan oral gavage in adult wild-type zebrafish, we then used microarrays to detail the global programme of gene expression after fucoidan treatment and identified distinct classes of up- and down-regulated genes during this process.
Project description:Hepatocellular carcinoma is the fourth leading cause of cancer-related deaths worldwide. Many carcinogens induce inflammation and cirrhosis, and eventually develop into liver cancer. Fucoidan is sulfated polysaccharide that is mainly found in brown seaweeds. In this study, we investigated the effects and mechanisms of low molecular weight fucoidan (i.e. oligo-fucoidan) preventing hepatocarcinogenesis using HBx,Src, and HBx,Src,p53-/+ transgenic zebrafish liver cancer model. Using an oligo-fucoidan oral gavage in adult transgenic zebrafish, we then used microarrays to detail the global programme of gene expression after fucoidan treatment and identified distinct classes of up- and down-regulated genes during this process.
Project description:Radiotherapy (RT) often causes unwanted side effects such as radiation-induced fibrosis (RIF) and second malignancies (SM). Fucoidan, a sulfated polysaccharide extracted from brown seaweed, has many biological effects including anti-inflammation and anti-tumor. In the present study, we investigated the radioprotective effect of Oligo-Fucoidan (OF) using zebrafish animal model. Using an oligo-fucoidan oral gavage in wild-type and adult transgenic zebrafish, we then used microarrays to detail the global programme of gene expression after fucoidan treatment and identified distinct classes of up- and down-regulated genes during this process.
Project description:Fucoidan, a sulfated polysaccharide extracted from brown seaweeds, possesses many biological activities including anti-inflammatory and anti-oxidant activities. We aimed to investigate the protective effects of fucoidan on dyslipidemia and atherosclerosis in apolipoprotein E-deficient mice (ApoEshl mice) and to elucidate its molecular targets in the liver by using a transcriptomic approach. For 12 weeks, ApoEshl mice were fed a high-fat diet (HFD) supplemented with either 1% or 5% fucoidan. Fucoidan supplementation significantly reduced tissue weight (liver and white adipose tissue), blood lipid, total-cholesterol (TC), triglyceride (TG), non-high density lipoprotein-cholesterol (Non-HDL-C), and glucose levels in HFD-fed ApoEshl mice but increased plasma lipoprotein lipase (LPL) activity and HDL-C levels. Fucoidan also reduced hepatic steatosis levels (liver size, TC and TG levels, and lipid peroxidation) and increased white adipose tissue LPL activity. DNA microarray analysis and quantitative reverse transcription-polymerase chain reaction demonstrated differential expression of genes encoding proteins involved in lipid metabolism, energy homeostasis, and insulin sensitivity, by activating Ppara and inactivating Srebf1. Fucoidan supplementation markedly reduced the thickness of the lipid-rich plaque, lipid peroxidation, and foaming macrophage accumulation in the aorta in HFD-fed ApoEshl mice. Thus, fucoidan supplementation appears to have anti-dyslipidemic and anti-atherosclerotic effects by inducing LPL activity and inhibiting the effects of inflammation and oxidative stress in HFD-fed ApoEshl mice.
Project description:To investigate the fucoidan-induced global change of signal transduction pathways, we prepared the bone marrow-derived dendritic cells (BMDCs) and treated them with fucoidan. We then performed gene expression profiling analysis using data obtained from RNA-seq of 6 different cells at one time point.