Sung Hak Lee

Plasma proteome analysis for anti-obesity and anti-diabetic potentials of chitosan oligosaccharides in ob/ob mice.

Altered levels of adipokines, derived as a result of distorted adipocytes, are the major factors responsible for changing biochemical parameters in obesity that leads to the development of metabolic disorders such as insulin resistance and atherosclerosis. In our previous reports, chitosan oligosaccharides (CO) were proved to inhibit the differentiation of 3T3‐L1 adipocytes. In the present study, an attempt was made to investigate the anti‐obesity and anti‐diabetic effect of CO on ob/ob mice, by means of differential proteomic analysis of plasma. This was followed by immunoblotting, and gene expression in adipose tissue to clarify the molecular mechanism. CO treatment showed reduced diet intake (13%), body weight gain (12%), lipid (29%) and glucose levels (35%). 2‐DE results showed differential levels of five proteins namely RBP4, apoE, and apoA‐IV by >2‐fold down‐regulation and by >2‐fold of apoA‐I and glutathione peroxidase (GPx) up‐regulation after CO treatment. Immunoblotting studies of adiponectin and resistin showed amelioration in their levels in plasma. Furthermore, the results of gene expressions for adipose tissue specific TNF‐α, and IL‐6 secretary molecules were also down‐regulated by CO treatment. Gene expressions of PPARγ in adipose tissue were in good agreement with the ameliorated levels of adipokines, thereby improving the pathological state. Taken together, CO might act as a potent down‐regulator of obesity‐related gene expression in ob/ob mice that may normalize altered plasma proteins to overcome metabolic disorders of obesity.

Proteomic analysis for inhibitory effect of chitosan oligosaccharides on 3T3-L1 adipocyte differentiation

In the present study, we performed a differential proteomic analysis using 2‐DE combined with MS to clarify the molecular mechanism for the suppressive effect of chitosan oligosaccharides (CO) during differentiation of adipocyte 3T3‐L1. Cell differentiation was significantly inhibited by CO at the concentration of 4 mg/mL. Protein mapping of adipocyte homogenates by 2‐DE revealed that numerous protein spots were differentially altered in response to CO treatment. Out of 50 identified proteins showing significant alterations, six were up‐regulated and 44 were down‐regulated by CO treatment in comparison to control mature adipocytes. Among them, most of the proteins are associated with lipid metabolism, cytoskeleton, and redox regulation, in which the levels of farnesyl diphosphate synthetase (FDS), dedicator of cytokinesis 9 (DOCK9), and chloride intracellular channel 1 (CLIC1) were significantly reduced (>two‐fold) with CO treatment. These results have not previously been examined in the context of adipogenesis, and thus can be used as novel biomarkers. Taken together with immunoblot analysis, it was concluded that the inhibitory effect of CO on adipocyte differentiation was mediated by C/EBPα and PPARγ pathway through significant downregulations of important adipogenic molecules such as fatty acid binding protein and glucose transporter 4.

Antitumor Activity of Water Extract of a Mushroom, Inonotus obliquus, against HT-29 Human Colon Cancer Cells

In the current study, it was demonstrated that the hot water extract of I. obliquus (IOWE) exerts inhibitory activity against the proliferation of human colon cancer cells (HT‐29). The inhibitory effect of IOWE on the growth of HT‐29 cancer cells was evaluated by treating cells with IOWE at concentrations of 0.25, 0.5 and 1.0 mg/mL for 24 or 48 h. The IOWE inhibited cell growth in a dose‐dependent manner, and this inhibition was accompanied by apoptotic cell death. The maximum inhibitory effect (56%) was observed when IOWE was treated at a concentration of 1.0 mg/mL for 48 h. The apoptotic effect of IOWE on HT‐29 cells was also confirmed by flow cytometric analysis. In addition, the apoptotic cell percentage was closely associated with down‐regulation of Bcl‐2 and up‐regulation of Bax and caspase‐3. The results suggest that IOWE would be useful as an antitumor agent via the induction of apoptosis and inhibition of the growth of cancer cells through up‐regulation of the expression of proapoptotic proteins and down‐regulation of antiapoptotic proteins. Copyright

A comparative proteomic analysis for capsaicin‐induced apoptosis between human hepatocarcinoma (HepG2) and human neuroblastoma (SK‐N‐SH) cells

The endogenous ROS levels were increased during HepG2 apoptosis, whereas they were decreased during SK‐N‐SH apoptosis in response to capsaicin treatments. We used 2‐DE‐based proteomics to analyze the altered protein levels in both cells, with special attention on oxidative stress proteins before and after capsaicin treatments. The 2‐DE analysis demonstrated that 23 proteins were increased and 26 proteins were decreased significantly (fold change>1.4) in capsaicin‐treated apoptotic HepG2 and SK‐N‐SH cells, respectively. The distinct effect of capsaicin‐induced apoptosis on the expression pattern of HepG2 proteins includes the downregulation of some antioxidant enzymes including aldose reductase (AR), catalase, enolase 1, peroxiredoxin 1, but upregulation of peroxiredoxin 6, cytochrome c oxidase, and SOD2. In contrast, most antioxidant enzymes were increased in SK‐N‐SH cells in response to capsaicin, where catalase might play a pivotal role in maintenance of low ROS levels in the course of apoptosis. The global gene expression for oxidative stress and antioxidant defense genes revealed that 84 gene expressions were not significantly different in HepG2 cells between control and capsaicin‐treated cells. In contrast, a number of oxidative genes were downregulated in SK‐N‐SH cells, supporting the evidence of low ROS environment in apoptotic SK‐N‐SH cells after capsaicin treatment. It was concluded that the different relationship between endogenous ROS levels and apoptosis of two cancer cells presumably resulted from complicated expression patterns of many oxidative stress and antioxidant genes, rather than the individual role of some classical antioxidant enzymes such as SOD and catalase.

Proteomic and transcriptomic analysis for streptozotocin‐induced diabetic rat pancreas in response to fungal polysaccharide treatments

In an attempt to search for novel biomarkers for monitoring diabetes prognosis, we examined the influence of the hypoglycemic fungal extracellular polysaccharides (EPS) on the differential change in pancreatic proteome and transcriptome in streptozotocin (STZ)‐induced diabetic rats using 2‐DE‐based protein mapping and oligonucleotide microarray analysis. The 2‐DE system separated more than 2000 individual spots, demonstrating that 34 proteins out of about 500 matched spots were differentially expressed. A total of 22 overexpressed and 12 underexpressed proteins in 2‐DE map were observed (p<0.05) between the healthy and diabetic rats, of which 26 spots were identified by PMF analysis. Of these, significant down regulation of carbonyl reductase (Cbr), hydroxymethylglutaryl‐CoA synthase (HMGCS), and putative human mitogen‐activated protein kinase activator with WD repeats‐binding protein (MAWDBP) in diabetic pancreas were reported for the first time in this study. When treated with EPS, all these four proteins were reverted to normal levels. The microarray analysis revealed that 96 out of 1272 genes were down‐ or up‐regulated in the diabetic rats and the altered transcript levels of many of these genes were reversed after EPS treatment. In particular, ROS generation in rat islets was significantly increased after STZ treatment, thereafter EPS treatment was likely to play a preventive role in β‐cell destruction mediated by STZ. Taken together, EPS may act as a potent regulator of gene expression for a wide variety of genes in diabetic rats, particularly in antioxidative stress, insulin biosynthesis, and cell proliferation.