👤 Liqiong Huang

Cell polarity proteins regulate tight junction formation and directional migration in epithelial cells. To date, the mechanism by which these polarity proteins assemble at the leading edge of migrating epithelial cells remains unclear. We report that occludin, a transmembrane protein, is localized at the leading edge of migrating cells and regulates directional cell migration. During migration, occludin knockdown disrupted accumulation of aPKC-Par3 and PATJ at the leading edge, and led to a disorganized microtubule network and defective reorientation of the microtubule organization center (MTOC). Phosphorylation of occludin at tyrosine 473 residue allowed recruitment of p85 alpha to the leading edge via association with its C-terminal SH2 domain. Loss of occludin attenuated activation of PI3K, leading to disorganization of the actin cytoskeleton and reduced cell protrusions. Our data indicate that occludin is required for the leading-edge localization of polarity proteins aPKC-Par3 and PATJ and promotes cell protrusion by regulating membrane-localized activation of PI3K. Show less

Liver is unique in its capability to regenerate after an injury. Liver regeneration after a 2/3 partial hepatectomy served as a classical model and is adopted frequently to study the mechanism of liver regeneration. In the present study, semiquantitative analysis of protein expression in mouse liver regeneration following partial hepatectomy was performed using an iTRAQ technique. Proteins from pre-PHx control livers and livers regenerating for 24, 48 and 72 h were extracted and inspected using 4-plex isotope labeling, followed by liquid chromatography fractionation, mass spectrometry and statistical differential analysis. A total of 827 proteins were identified in this study. There were 270 proteins for which quantitative information was available at all the time points in both biologically duplicate experiments. Among the 270 proteins, Car3, Mif, Adh1, Lactb2, Fabp5, Es31, Acaa1b and LOC100044783 were consistently down-regulated, and Mat1a, Dnpep, Pabpc1, Apoa4, Oat, Hpx, Hp and Mt1 were up-regulated by a factor of at least 1.5 from that of the controls at one time point or more. The regulation of each differential protein was also demonstrated by monitoring its time-dependent expression changes during the regenerating process. We believe this is the first report to profile the protein changes in liver regeneration utilizing the iTRAQ proteomic technique. Show less

To explore the relationship between serum apolipoprotein A5 (ApoA5) and lipid profile or high sensitive C-reactive protein (hs-CRP) in patients with acute coronary syndrome (ACS). Serum apoA5 and hs-CRP levels were measured by ELISA and immunoturbidimetry in control subjects (n = 232), patients with stable angina (SA, n = 127), unstable angina (UA, n = 116) and acute myocardial infarction (AMI, n = 112). Triglyceride (TG), total cholesterol (TC), high density lipoprotein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C) were also measured. Compared with controls [(108.7 +/- 23.2) microg/L] and SA patients [(78.3 +/- 20.2) microg/L], serum ApoA5 level was significantly increased in UA [(340.6 +/- 63.5) microg/L] and AMI patients [(373.2 +/- 73.8) microg/L] (all P < 0.05). ApoA5 was positively correlated with TG (r = 0.63 and 0.67, respectively, all P < 0.05) and hs-CRP (r = 0.57 and 0.55, respectively, all P < 0.05) in UA and AMI patients but there were no significant correlations between ApoA5 and TC, HDL-C and LDL-C in ACS patients (all P > 0.05). Increased serum apoA5 level and the positive correlation between ApoA5 and serum TG and hs-CRP in ACS patients might reflect increased inflammation responses in ACS patients. Show less

Combining statin and fibrate in clinical practice provides a greater reduction of triglycerides than either drug given alone, but the mechanism for this effect is poorly understood. Apolipoprotein AV (apoAV) has been implicated in triglyceride metabolism. This study was designed to investigate the effect of the combination of statin and fibrate on apoAV and the underlying mechanism(s). Hypertriglyceridaemia was induced in rats by giving them 10% fructose in drinking water for 2 weeks. They were then treated with atorvastatin, fenofibrate or the two agents combined for 4 weeks, and plasma triglyceride and apoAV measured. We also tested the effects of these two agents on triglycerides and apoAV in HepG2 cells in culture. Western blot and reverse transcription polymerase chain reaction was used to measure apoAV and peroxisome proliferator-activated receptor-alpha (PPARalpha) expression. The combination of atorvastatin and fenofibrate resulted in a greater decrease in plasma triglycerides and a greater increase in plasma and hepatic apoAV than either agent given alone. Hepatic expression of the PPARalpha was also more extensively up-regulated in rats treated with the combination. A similar, greater increase in apoAV and a greater decrease in triglycerides were observed following treatment of HepG2 cells pre-exposed to fructose), with the combination. Adding an inhibitor of PPARalpha (MK886) abolished the effects of atorvastatin on HepG2 cells. A combination of atorvastatin and fenofibrate increased apoAV and decreased triglycerides through up-regulation of PPARalpha. Show less

Increased triglyceride (TG) occurs in patients with acute coronary syndrome (ACS), and apolipoprotein AV (apoAV) has been shown to lower TG levels. In the present study, we investigated plasma apoAV level and its relationship with TG and C-reactive protein (CRP) in ACS patients. A total of 459 subjects were recruited and categorized into control group (n = 116), stable angina (SA) group (n = 115), unstable angina group (n = 116) and acute myocardial infarction group (n = 112). Plasma apoAV level was measured by a sandwich ELISA assay. Compared with controls ((100.27 +/- 22.44) ng/ml), plasma apoAV was decreased in SA patients ((76.54 +/- 16.91) ng/ml) but increased in patients with unstable angina ((330.89 +/- 66.48) ng/ml, P < 0.05) or acute myocardial infarction ((368.66 +/- 60.53) ng/ml, P < 0.05). Inverse correlations between apoAV and TG were observed in the control or stable angina groups (r = -0.573 or -0.603, respectively, P < 0.001), whereas positive correlations were observed in the patients with unstable angina or acute myocardial infarction (r = 0.696 or 0.690, respectively, P < 0.001). Furthermore, a positive relationship between apoAV and CRP was observed in the ACS patients but not in the non-ACS subjects. The plasma apoAV concentration is increased and positively correlates with TG and CRP in ACS patients. Show less

Dyslipidemia is common in patients with acute coronary syndromes (ACS) but the mechanism remains unclear. Apolipoprotein AV (apoAV), a novel member of apolipoprotein family, is involved in lipid metabolism. This study was to investigate plasma apoAV level and its association with lipids and high-sensitivity C-reactive protein (hs-CRP) in ACS patients. ACS patients (n=228) and healthy volunteers (n=232) were included. Plasma apoAV levels were measured by an ELISA method. Compared with controls, ACS patients had higher plasma apoAV, hs-CRP, triglycerides, total cholesterol and LDL cholesterol, as well as lower HDL cholesterol. Interestingly, a positive correlation was observed between apoAV and triglycerides in ACS patients, as compared with a negative correlation in controls. Notably, logistic regression analysis showed that plasma apoAV level was an independent predictor of ACS (OR=0.82, 95% CI 0.70-0.95, p<0.05). Furthermore, both apoAV and triglycerides were positively associated with hs-CRP in ACS patients. However, no significant correlations between apoAV and cholesterol including total cholesterol, HDL cholesterol and LDL cholesterol were observed in ACS patients. Thus, apoAV is an independent predictor of ACS although increased plasma apoAV level is positively correlated with triglycerides in ACS patients. Moreover, plasma cholesterol levels are not influenced by apoAV in ACS patients. Show less

START-dependent transcription in Saccharomyces cerevisiae is regulated by two transcription factors SBF and MBF, whose activity is controlled by the binding of the repressor Whi5. Phosphorylation and removal of Whi5 by the cyclin-dependent kinase (CDK) Cln3-Cdc28 alleviates the Whi5-dependent repression on SBF and MBF, initiating entry into a new cell cycle. This Whi5-SBF/MBF transcriptional circuit is analogous to the regulatory pathway in mammalian cells that features the E2F family of G1 transcription factors and the retinoblastoma tumor suppressor protein (Rb). Here we describe genetic and biochemical evidence for the involvement of another CDK, Pcl-Pho85, in regulating G1 transcription, via phosphorylation and inhibition of Whi5. We show that a strain deleted for both PHO85 and CLN3 has a slow growth phenotype, a G1 delay, and is severely compromised for SBF-dependent reporter gene expression, yet all of these defects are alleviated by deletion of WHI5. Our biochemical and genetic tests suggest Whi5 mediates repression in part through interaction with two histone deacetylases (HDACs), Hos3 and Rpd3. In a manner analogous to cyclin D/CDK4/6, which phosphorylates Rb in mammalian cells disrupting its association with HDACs, phosphorylation by the early G1 CDKs Cln3-Cdc28 and Pcl9-Pho85 inhibits association of Whi5 with the HDACs. Contributions from multiple CDKs may provide the precision and accuracy necessary to activate G1 transcription when both internal and external cues are optimal. Show less

Previously, a genome-wide scan has identified a nonsynonymous single nucleotide polymorphism (rs3812316, G771C, Gln241His) in the MLXIPL gene that is associated with the level of plasma triglycerides. However, no data are available on the association of this polymorphism with coronary artery disease (CAD) in the Chinese population. The aim of this study was to evaluate the association between a gene polymorphism related to triglyceride metabolism and CAD. The genotype of the polymorphism in the MLXIPL gene was determined in 352 CAD patients and 152 CAD-free subjects. All of the participants were selected to study the MLXIPL gene rs3812316 polymorphism using the polymerase chain reaction restriction fragment length polymorphism method. In Chinese participants, we observed that there was a significant difference in genotype between the cases and controls (p = 0.002). After allowance for potential confounders, unconditional logistic analysis revealed that the SNP was significantly related to a risk in CAD patients (adjusted OR 2.96, 95% CI 1.30-5.08; p =0.004). We also found that there was a significant association between the single nucleotide polymorphism and plasma triglyceride levels (OR 1.28, 95% CI 1.061-1.542; p < 0.05). The gene sequence variation in the MLXIPL gene may serve as a novel genetic marker for the risk of significant CAD. Show less

To explore the possible mechanism of the inhibitory effect of liver X receptor alpha (LXRalpha) on lipopolysaccharide (LPS)-induced inflammation in mouse Kupffer cells (KCs). The KCs isolated from the liver of male KM mice and cultured in RPMI 1640 containing 20% FBS for 24 h were divided into control, LPS, T0901317, and LPS+T0901317 groups with corresponding treatments. The expressions of LXRalpha, interferon regulatory factor 3 (IRF3) and glucocorticoid receptor interacting protein 1 (GRIP1) in the KCs were detected by Western blotting. The levels of interferon beta (IFNbeta), tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) in the supernatant were detected by enzyme-linked immunosorbent assay (ELISA). The level of LXRalpha protein was highest in T0901317 group and lowest in LPS group, and was significantly higher in LPS+T0901317 group than in LPS group but lower than in T0901317 group (P<0.05). The levels of IRF3 and GRIP1 protein were the highest in LPS group, and significantly lowered by T0901317 treatment (P<0.05). The expression of IRF3 and GRIP1 proteins in LPS group and LPS+ T0901317 group were significantly higher than those in the control and T0901317 groups (P<0.05). The concentration of IFN-beta was significantly higher in LPS group than in the control and T0901317 group (P<0.05), and decreased in LPS+T0901317 group in comparison with that in LPS group (P<0.05). IFN-beta was the lowest in T0901317 group. The levels of TNF-alpha and IL-1beta were the highest in LPS group (P<0.05), and comparable between the other 3 groups (P>0.05). Pre-treatment with T0901317 before LPS stimulation can suppress the expressions of IRF3 and GRIP1 to inhibit the inflammation and hence Kupffer cell activation. Show less

Nicotine stimulation regulates expression of a diversity of genes, but the underlying mechanisms are largely unknown. MicroRNAs (miRNAs) are short endogenous RNAs known to post-transcriptionally regulate gene expression. To test our hypothesis that miRNAs could mediate nicotine's effect on gene expression regulation, we profiled miRNA expression to explore to what extent miRNAs are modulated by nicotine. Using a rodent miRNA microarray and rat PC12 cell model, we revealed that nicotine selectively modulates expression of multiple miRNAs, indicating that the miRNA pathway is one of cellular mechanisms involved in gene expression regulated by nicotine. Specifically, we demonstrated that nicotine increases expression of miR-140*, coordinated with the nicotine-augmented expression of its host gene WWP2. Further, we demonstrated that miR-140* targets the 3'-untranslated region of dynamin 1 gene (Dnm1), by direct base-pairing. This targeting represses gene translation in the luciferase reporter assay and induces messenger RNA degradation in Dnm1 expression analysis. Consequently, our data indicate that nicotine regulates Dnm1 expression via the miRNA pathway. Because dynamin 1 has an essential role in synaptic endocytosis in the central nervous system, nicotine-induced miRNA-mediated dynamin 1 expression regulation may illustrate its importance in neural plasticity, which underlies a molecular mechanism of nicotine addiction. Show less

Our objective was to analyze the changes in the protein expression profiles of peripheral blood mononuclear cells (PBMCs) in patients with systemic lupus erythematosus (SLE). Peripheral blood was obtained from patients with SLE and healthy controls. 2-D gel electrophoresis was performed, and gels were silver-stained. Differentially expressed protein spots were detected, some of which were identified by MALDI-TOF spectrometry. Match rates of 71% +/- 4% and 72% +/- 4% were gotten for control and patient gels, respectively. 791 +/- 17 spots were detected for control gels and 781 +/- 17 for patient gels. Eleven protein spots were up-regulated, and 9 protein spots were down-regulated in patients with SLE. Five differentially expressed proteins were identified as immunoglobulin J chain, apolipoprotein A-IV precursor, calprotectin L1H and zinc finger protein subfamily 1A (all up-regulated) and glutathione S-transferase (down-regulated), some of which had previously been shown to play a potential role in the pathogenesis of SLE. We conclude there are significant changes in the 2-D maps of PBMCs in patients with SLE and applying this proteomic approach may be a useful way to gain novel insights into SLE. Show less

Blood pressure (BP) is a complex trait regulated by the interaction among multiple physiologic regulatory systems, likely involving numerous genes that lead to inconsistent findings in genetic studies. One possibility of failure to replicate some single-locus results is that the underlying genetics of hypertension is based on multiple genes with minor effects. To learn the association between 17 single nucleotide polymorphisms (SNPs) in 13 cardiovascular disease-predisposing genes and blood pressure of Han males, the 17 SNPs genotypes of 375 Han males were detected and analyzed with BaiO gene chip. The relationship between the SNPs and blood pressure was analyzed with variance analysis and multiple linear regression analysis. Variance analysis and/or multiple linear regression showed that: systolic blood pressure (SBP) was increasing with the elevation of year; AGT(235)M, ApoE(112,158)E4, and SerpinA3(rs4934)A were relative to the increase of SBP; AGT(235)M, ET-2(985)G, ApoC3(3206)T, and ApoE(112,158)E4 may have had some relation with diastolic blood pressure (DBP) elevation; and ApoB(Xba) + was associated with the increase of pulse pressure (PP). These findings support the multigenic nature of the etiology of essential hypertension and propose a potential gene-gene interactive model for future studies. Show less

Canonical Wnt/beta-catenin signaling has central roles in development and diseases, and is initiated by the action of the frizzled (Fz) receptor, its coreceptor LDL receptor-related protein 6 (Lrp6), and the cytoplasmic dishevelled (Dvl) protein. The functional relationships among Fz, Lrp6 and Dvl have long been enigmatic. We demonstrated previously that Wnt-induced Lrp6 phosphorylation via glycogen synthase kinase 3 (Gsk3) initiates Wnt/beta-catenin signaling. Here we show that both Fz and Dvl functions are critical for Wnt-induced Lrp6 phosphorylation through Fz-Lrp6 interaction. We also show that axin, a key scaffolding protein in the Wnt pathway, is required for Lrp6 phosphorylation via its ability to recruit Gsk3, and inhibition of Gsk3 at the plasma membrane blocks Wnt/beta-catenin signaling. Our results suggest a model that upon Wnt-induced Fz-Lrp6 complex formation, Fz recruitment of Dvl in turn recruits the axin-Gsk3 complex, thereby promoting Lrp6 phosphorylation to initiate beta-catenin signaling. We discuss the dual roles of the axin-Gsk3 complex and signal amplification by Lrp6-axin interaction during Wnt/beta-catenin signaling. Show less

As an epigenetic regulator, the transcriptional intermediary factor 1beta (TIF1beta)/KAP1/TRIM28) has been linked to gene expression and chromatin remodeling at specific loci by association with members of the heterochromatin protein 1 (HP1) family and various other chromatin factors. The interaction between TIF1beta and HP1 is crucial for heterochromatin formation and maintenance. The HP1-box, PXVXL, of TIF1beta is responsible for its interaction with HP1. However, the underlying mechanism of how the interaction is regulated remains poorly understood. This work demonstrates that TIF1beta is phosphorylated on Ser473, the alteration of which is dynamically associated with cell cycle progression and functionally linked to transcriptional regulation. Phosphorylation of TIF1beta/Ser473 coincides with the induction of cell cycle gene cyclin A2 at the S-phase. Interestingly, chromatin immunoprecipitation demonstrated that the promoter of cyclin A2 gene is occupied by TIF1beta and that such occupancy is inversely correlated with Ser473 phosphorylation. Additionally, when HP1beta was co-expressed with TIF1beta/S473A, but not TIF1beta/S473E, the colocalization of TIF1beta/S473A and HP1beta to the promoters of Cdc2 and Cdc25A was enhanced. Non-phosphorylated TIF1beta/Ser473 allowed greater TIF1beta association with the regulatory regions and the consequent repression of these genes. Consistent with possible inhibition of TIF1beta's corepressor function, the phosphorylation of the Ser473 residue, which is located near the HP1-interacting PXVXL motif, compromised the formation of TIF1beta-HP1 complex. Finally, we found that the phosphorylation of TIF1beta/Ser473 is mediated by the PKCdelta pathway and is closely linked to cell proliferation. The modulation of HP1beta-TIF1beta interaction through the phosphorylation/de-phosphorylation of TIF1beta/Ser473 may constitute a molecular switch that regulates the expression of particular genes. Higher levels of phosphorylated TIF1beta/Ser473 may be associated with the expression of key regulatory genes for cell cycle progression and the proliferation of cells. Show less

The HP1 family of evolutionarily conserved proteins regulates heterochromatin packaging, in addition to a less defined role in the regulation of euchromatic genes. To examine the possible role of HP1 proteins in fetal prostate development and prostate cancer the protein expression of HP1alpha, beta and gamma was evaluated in human archival tissue. Tissue sections from human prostate cancer and fetal prostate were examined using antibodies against HP1 isoforms to evaluate HP1 modulation in cancer and development. Western blot analysis of HP1 proteins was also performed in extracts of cultured prostate cancer cells. HP1alpha, beta and gamma are differentially regulated in various cellular compartments in prostate development. HP1alpha is not expressed at 14 or 24 weeks of prostate development but it is expressed in adult prostate tissue. HP1beta is highly expressed at 14 and 24 weeks, and it appears predominantly in epithelial cells compared to HP1gamma, which is expressed at equal levels in epithelial and stromal cells. All 3 HP1 isoforms show altered expression in prostate cancer compared to that in normal adult prostate tissue. HP1 proteins are tightly regulated during prostate development. In the adult prostate HP1alpha, beta and gamma antibodies detect high levels of HP1 antigen in a contiguous layer of epithelial cells. However, the detection of HP1 in prostate cancer ranges from undetectable to inconsistent staining of noncontiguous epithelial cells. Show less

Pathogenic fungus Cryptococcus neoformans has a predilection for the central nervous system causing devastating meningoencephalitis. Traversal of C. neoformans across the blood-brain barrier (BBB) is a crucial step in the pathogenesis of C. neoformans. Our previous studies have shown that the CPS1 gene is required for C. neoformans adherence to the surface protein CD44 of human brain microvascular endothelial cells (HBMEC), which constitute the BBB. In this report, we demonstrated that C. neoformans invasion of HBMEC was blocked in the presence of G109203X, a protein kinase C (PKC) inhibitor, and by overexpression of a dominant-negative form of PKCalpha in HBMEC. During C. neoformans infection, phosphorylation of PKCalpha was induced and the PKC enzymatic activity was detected in the HBMEC membrane fraction. Our results suggested that the PKCalpha isoform might play a crucial role during C. neoformans invasion. Immunofluorescence microscopic images showed that induced phospho-PKCalpha colocalized with beta-actin on the membrane of HBMEC. In addition, cytochalasin D (an F-filament-disrupting agent) inhibited fungus invasion into HBMEC in a dose-dependent manner. Furthermore, blockage of PKCalpha function attenuated actin filament activity during C. neoformans invasion. These results suggest a significant role of PKCalpha and downstream actin filament activity during the fungal invasion into HBMEC. Show less

The asymmetric unit of the title compound, {[Cu(CO(3))(C(14)H(14)N(4))(1.5)] x 0.5 C(14)H(14)N(4) x 5 H(2)O}(n), contains one Cu(II) cation in a slightly distorted square-pyramidal coordination environment, one CO(3)(2-) anion, one full and two half 1,4-bis(imidazol-1-ylmethyl)benzene (bix) ligands, one half-molecule of which is uncoordinated, and five uncoordinated water molecules. One of the coordinated bix ligands and the uncoordinated bix molecule are situated about centers of symmetry, located at the centers of the benzene rings. The coordinated bix ligands link the copper(II) ions into a [Cu(bix)(1.5)](n) molecular ladder. These molecular ladders do not form interpenetrated ladders but are arranged in an ABAB parallel terrace, i.e. with the ladders arranged one above another, with sequence A translated with respect to B by 8 A. To best of our knowledge, this arrangement has not been observed in any of the molecular ladder frameworks synthesized to date. The coordination environment of the Cu(II) atom is completed by two O atoms of the CO(3)(2-) anion. The framework is further strengthened by extensive O-H...O and O-H...N hydrogen bonds involving the water molecules, the O atoms of the CO(3)(2-) anion and the N atoms of the bix ligands. This study describes the first example of a molecular ladder coordination polymer based on bix and therefore demonstrates further the usefulness of bix as a versatile multidentate ligand for constructing coordination polymers with interesting architectures. Show less

Langer-Giedion syndrome results from a microdeletion at 8q24.1 encompassing the EXT1 and the adjacent TRPS1 gene. We report on a boy with an oligo array-cgh characterized small microdeletion involving EXT1 alone but with some features of Langer-Giedion syndrome suggesting a functional disturbance of TRPS1. This boy, in addition to a mild Langer-Giedion like phenotype, also had some unusual features including prominent toe pads and fat pads on the soles of his feet similar to those described in Pierpont syndrome. Show less

As a model for both multistep and multipathway carcinogenesis, colorectal neoplastic progression provides paradigms for researching both oncogenes and tumor suppressor genes (TSGs). However, the mechanism of colorectal cancer (CRC) is not completely understood, and many genes may be involved in the colorectal carcinogenesis. The purpose of this study was to screen for the potential TSGs on chromosome 1q31.1-32.1 in Chinese patients with sporadic colorectal cancer, to explore whether colorectal cancer in the Chinese population has unique genetic alterations and determine whether other putative TSGs exist and contribute to colon carcinogenesis. Six polymorphic microsatellite markers, at a density of approximately one marker in every 1.6 cM, were chosen for refined loss of heterozygosity (LOH) mapping of 1q31.1-32.1. Eighty-three colorectal cancer patients' tumor and normal DNA were analyzed via polymerase chain reaction (PCR) for these microsatellite markers. PCR products were eletrophoresed on an ABI 377 DNA sequencer. Genescan 3.1 and Genotype 2.1 software were used for LOH scanning and analysis. On the basis of refined LOH mapping results, we undertook a microarray-based expression screening to identify tumor association genes in 19 of the CRC cases. The average LOH frequency of 1q31.1-32.1 was 24.41%, with the highest frequency of 36.73% (18/49) at D1S2622, and the lowest of 16.42% (11/67) at D1S412. A minimal region of frequent deletion was located within a 2 cM genomic segment at D1S413-D1S2622. There was no significant association between LOH of any marker in the studied regions and the clinicopathological data (patient sex, age, tumor size, growth pattern, or Dukes stage). On the basis of refined mapping results, we chose 25 genes located in the D1S413-D1S2622 (1q31.3-32.1) region and presented a microarray-based high throughput screening approach in 19 sporadic CRC cases to identify candidate CRC related tumor suppressor genes. This study found 4 significantly down-expressed genes, including CSRP1, LMOD1, PPP1R12B and CFHL3. There was no significant association between expression levels of CFHL3, CSRP1, LMOD1, PPP1R12B and the clinicopathological data. By database searching, CSRP1 was hypothesized to be a colorectal cancer related tumor suppressor gene. Through detailed deletion mapping, we found that the 1q31.3-32.1 region might harbor one or more colorectal cancer related tumor suppressor gene (s). And by microarray-based high-throughput screening of candidate genes located in this region and by subsequent database searching, we present the first evidence that CSRP1 might be involved in the progression of CRC. Show less

Low density lipoprotein receptor (LDLR) mutations cause familial hypercholesterolemia and early atherosclerosis. ABCA1 facilitates free cholesterol efflux from peripheral tissues. We investigated the effects of LDLR deletion (LDLR(-/-)) on ABCA1 expression. LDLR(-/-) macrophages had reduced basal levels of ABCA1, ABCG1, and cholesterol efflux. A high fat diet increased cholesterol in LDLR(-/-) macrophages but not wild type cells. A liver X receptor (LXR) agonist induced expression of ABCA1, ABCG1, and cholesterol efflux in both LDLR(-/-) and wild type macrophages, whereas expression of LXRalpha or LXRbeta was similar. Interestingly, oxidized LDL induced more ABCA1 in wild type macrophages than LDLR(-/-) cells. LDL induced ABCA1 expression in wild type cells but inhibited it in LDLR(-/-) macrophages in a concentration-dependent manner. However, lipoproteins regulated ABCG1 expression similarly in LDLR(-/-) and wild type macrophages. Cholesterol or oxysterols induced ABCA1 expression in wild type macrophages but had little or inhibitory effects on ABCA1 expression in LDLR(-/-) macrophages. Active sterol regulatory element-binding protein 1a (SREBP1a) inhibited ABCA1 promoter activity in an LXRE-dependent manner and decreased both macrophage ABCA1 expression and cholesterol efflux. Expression of ABCA1 in animal tissues was inversely correlated to active SREBP1. Oxysterols inactivated SREBP1 in wild type macrophages but not in LDLR(-/-) cells. Oxysterol synergized with nonsteroid LXR ligand induced ABCA1 expression in wild type macrophages but blocked induction in LDLR(-/-) cells. Taken together, our studies suggest that LDLR is critical in the regulation of cholesterol efflux and ABCA1 expression in macrophage. Lack of the LDLR impairs sterol-induced macrophage ABCA1 expression by a sterol regulatory element-binding protein 1-dependent mechanism that can result in reduced cholesterol efflux and lipid accumulation in macrophages under hypercholesterolemic conditions. Show less

The PIK3C3 gene has been implicated as a candidate gene for schizophrenia by functional evidence and genetic association studies. A series of previous studies have found susceptibility SNPs in promoter region. To further verify its susceptibility to schizophrenia in the Chinese population and the function of the polymorphisms, we performed a case control study in 556 unrelated schizophrenia patients and 563 normal controls as well as an in vitro functional analysis. In our association analysis of-432C-/T, we discovered obvious differences in allele frequency between patients and controls (P=0.017). A T/C haplotype constructed by -432C-/T and -86insC, which are tightly linked with each other (r(2)=1) can significantly weaken promoter's transcriptional activity by 20% (p=0.002 by t-test). Though we cannot exclude the possibility that susceptibility of -432C-/T is caused by its linkage disequilibrium with other causal variants, our results do support PIK3C3 play a significant role in the etiology of schizophrenia. Show less

Guillain-Barré Syndrome (GBS) is a rare autoimmune inflammatory polyneuropathy with a high risk of respiratory failure and unclear pathogenesis. Currently, there are no valid biomarkers for diagnosis of GBS. We used 2-DE and MS to analyze the protein profiles of five pairs of cerebrospinal fluid (CSF) samples of the GBS patients and the patient controls. Three proteins (orosomucoid, haptoglobin and apolipoprotein A-IV) were up-regulated, and two proteins (prostaglandin D2 synthase and transthyretin) were down-regulated in the CSF of the GBS patients. The CSF haptoglobin level, quantified by enzyme-linked immunosorbent assay, was significantly higher in the GBS patients (12.44 ± 2.70 μg/mL) compared to the chronic inflammatory demyelinating polyradiculoneuropathy (2.82 ± 0.83 μg/mL), viral meningitis (3.57 ± 0.97 μg/mL) and control patients (1.44 ± 0.35 μg/mL, p<0.05). This study indicated that protein profile analysis using a combination of 2-DE and MS provides an effective strategy for elucidating the pathogenesis and identifying potential CSF biomarkers for GBS. The raised intrathecal synthesis of haptoglobin specifically only in GBS patients, but not in patients with other neurological diseases examined, provides evidence of central nervous system involvement in GBS, and may be used as a potential diagnostic marker for GBS. Show less

Reception and interpretation of environmental stimuli is critical for the survival of all organisms. Here, we show that the ablation of BBS1 and BBS4, two genes mutated in Bardet-Biedl syndrome and that encode proteins that localize near the centrioles of sensory neurons, leads to alterations of s.c. sensory innervation and trafficking of the thermosensory channel TRPV1 and the mechanosensory channel STOML3, with concomitant defects in peripheral thermosensation and mechanosensation. The thermosensory phenotype is recapitulated in Caenorhabditis elegans, because BBS mutants manifest deficient thermosensory responses at both physiological and nociceptive temperatures and defective trafficking of OSM-9, a polymodal sensory channel protein and a functional homolog of TRPV1 or TRPV4. Our findings suggest a hitherto unrecognized, but essential, role for mammalian basal body proteins in the acquisition of mechano- and thermosensory stimuli and highlight potentially clinical features of ciliopathies in humans. Show less

To identify and characterize gene expression changes associated with photoreceptor cell loss in a Bbs4-knockout mouse model of retinal degeneration. Differential gene expression in the eyes of 5-month-old Bbs4(-/-) mice undergoing retinal degeneration were analyzed using gene microarrays (Affymetrix, Santa Clara, CA). Elevated ocular transcripts were confirmed by Northern blotting of RNA from Bbs4(-/-) and three additional mouse models of Bardet-Biedl Syndrome (BBS). TUNEL assays and transmission electron microscopy were used to study cell death and photoreceptor morphology in these mice. Three hundred fifty-four probes were differentially expressed in Bbs4(-/-) eyes compared with controls using a twofold cutoff. Numerous vision-related transcripts decreased because of photoreceptor cell loss. Increased expression of the stress response genes Edn2, Lcn2, Serpina3n, and Socs3 was noted at 5 months of age and as early as postnatal week 4 in the eyes of four BBS mouse model strains. A burst of apoptotic activity in the photoreceptor outer nuclear layer at postnatal week 2 and highly disorganized outer segments by postnatal weeks 4 to 6 was observed in all four strains. The specific loss of photoreceptors in Bbs4(-)(/)(-) mice allows us to identify a set of genes that are preferentially expressed in photoreceptors compared with other cell types found in the eye and is a valuable resource in the continuing search for genes involved in retinal disease. The molecular and morphologic changes observed in young BBS animal model eyes implies that BBS proteins play a critical, early role in establishing the correct structure and function of photoreceptors. Show less

Cryptococcus neoformans is a pathogenic yeast that often causes devastating meningoencephalitis in immunocompromised individuals. We have previously identified the C. neoformans CPS1 gene, which is required for a capsular layer on the outer cell wall. In this report, we investigate the function of the CPS1 gene and its pathogenesis. We demonstrated that treatment of yeast with either 4-methylumbelliferone or hyaluronidase resulted in a reduction of the level of C. neoformans binding to human brain microvascular endothelial cells (HBMEC). Yeast extracellular structures were also altered accordingly in hyaluronidase-treated cells. Furthermore, observation of yeast strains with different hyaluronic acid contents showed that the ability to bind to HBMEC is proportional to the hyaluronic acid content. A killing assay with Caenorhabditis elegans demonstrated that the CPS1 wild-type strain is more virulent than the cps1Delta strain. When CPS1 is expressed in Saccharomyces cerevisiae and Escherichia coli, hyaluronic acid can be detected in the cells. Additionally, we determined by fluorophore-assisted carbohydrate electrophoretic analysis that hyaluronic acid is a component of the C. neoformans capsule. The size of hyaluronic acid molecules is evaluated by gel filtration and transmission electron microscopy studies. Together, our results support that C. neoformans CPS1 encodes hyaluronic acid synthase and that its product, hyaluronic acid, plays a role as an adhesion molecule during the association of endothelial cells with yeast. Show less

MEKK3 is a mitogen-activated protein kinase kinase kinase that participates in various signaling pathways. One of its functions is to activate the ERK5 signal pathway by phosphorylating and activating MEK5. MEKK3 and MEK5 each harbors a PB1 domain in the N-terminus, and they form a heterodimer via PB1-PB1 domain interaction that was reported to be indispensable to the activation of MEK5. Using NMR spectroscopy, we show here that a prolyl isomerization of the Gln38-Pro39 bond is present in MEKK3 PB1, which is the first case of structural heterogeneity within PB1 domains. We have solved the solution structures of both isomers and found a major difference between them in the Pro39 region. Residues Gly37-Leu40 form a type VIb beta-turn in the cis conformation, whereas no obvious character of beta-turn was observed in the trans conformation. Backbone dynamics studies have unraveled internal motions in the beta3/beta4-turn on a microsecond-millisecond time scale. Further investigation of its binding properties with MEK5 PB1 has demonstrated that MEKK3 PB1 binds MEK5 PB1 tightly with a Kd of about 10(-8) M. Mutagenesis analysis revealed that residues in the basic cluster of MEKK3 PB1 contributes differently to the PB1-PB1 interaction. Residues Lys 7 and Arg 5 play important roles in the interaction with MEK5 PB1. Taken together, this study provides new insights into structural details of MEKK3 PB1 and its binding properties with MEK5 PB1. Show less

It is unclear whether cardiac hypertrophy and hypertrophy-related pathways will be induced by long-term intermittent hypoxia. Thirty-six Sprague-Dawley rats were randomly assigned into three groups: normoxia, and long-term intermittent hypoxia (12% O(2), 8 h per day) for 4 weeks (4WLTIH) or for 8 weeks (8WLTIH). Myocardial morphology, trophic factors and signalling pathways in the three groups were determined by heart weight index, histological analysis, Western blotting and reverse transcriptase-polymerase chain reaction from the excised left ventricle. The ratio of whole heart weight to body weight, the ratio of left ventricular weight to body weight, the gross vertical cross-section of the heart and myocardial morphological changes were increased in the 4WLTIH group and were further augmented in the 8WLTIH group. In the 4WLTIH group, tumour necrosis factor-alpha(TNFalpha), insulin-like growth factor (IGF)-II, phosphorylated p38 mitogen-activated protein kinase (P38), signal transducers and activators of transcription (STAT)-1 and STAT-3 were significantly increased in the cardiac tissues. However, in the 8WLTIH group, in addition to the above factors, interleukin-6, mitogen-activated protein kinase (MEK)5 and extracellular signal-regulated kinase (ERK)5 were significantly increased compared with the normoxia group. We conclude that cardiac hypertrophy associated with TNFalpha and IGF-II was induced by intermittent hypoxia. The longer duration of intermittent hypoxia further activated the eccentric hypertrophy-related pathway, as well as the interleukin 6-related MEK5-ERK5 and STAT-3 pathways, which could result in the development of cardiac dilatation and pathology. Show less

APPL1 is an effector of the small GTPase Rab5. Together, they mediate a signal transduction pathway initiated by ligand binding to cell surface receptors. Interaction with Rab5 is confined to the amino (N)-terminal region of APPL1. We report the crystal structures of human APPL1 N-terminal BAR-PH domain motif. The BAR and PH domains, together with a novel linker helix, form an integrated, crescent-shaped, symmetrical dimer. This BAR-PH interaction is likely conserved in the class of BAR-PH containing proteins. Biochemical analyses indicate two independent Rab-binding sites located at the opposite ends of the dimer, where the PH domain directly interacts with Rab5 and Rab21. Besides structurally supporting the PH domain, the BAR domain also contributes to Rab binding through a small surface region in the vicinity of the PH domain. In stark contrast to the helix-dominated, Rab-binding domains previously reported, APPL1 PH domain employs beta-strands to interact with Rab5. On the Rab5 side, both switch regions are involved in the interaction. Thus we identified a new binding mode between PH domains and small GTPases. Show less