TGF-ß1 Promotes Hepatocellular Carcinoma Invasion and Metastasis via ERK Pathway-Mediated FGFR4 Expression.

BACKGROUND/AIMS: TGF-ß1 is beneficial during early liver disease but is tumor-progressive during late stages especially for hepatocellular carcinoma (HCC). Thus, exploring the underlying mechanisms may provide information about a potentially therapeutic role of TGF-ß1 in HCC. METHODS: Western blot and real-time quantitative PCR were used to quantify FGFR4 expression in HCC cell lines and a normal liver cell line. After constructing the best silencing FGFR4 expression vector, migration and invasiveness of TGF-ß1 in HCC was studied in vitro and in vivo. Western blot was used to study the mechanism of TGF-ß1 induction on FGFR4 expression with various inhibitors. RESULTS: HepG2 cell lines had the most FGFR4 expression, and data show that silencing FGFR4 suppressed cell proliferation, invasion and migration in HCC induced by TGF-ß1 in vitro and in vivo. Moreover, TGF-ß1 induced FGFR4 expression through the ERK pathway. CONCLUSION: Promoting FGFR4 expression via the ERK pathway, TGF-ß1 contributes to HCC invasion and metastasis.

Zinc finger protein 191 inhibits hepatocellular carcinoma metastasis through discs large 1-mediated yes-associated protein inactivation.

UNLABELLED: Interplay between cell polarity module Scribble-Lethal Giant Larvae-Discs Large 1 (DLG1) and Yes-associated protein (YAP) appears critical in tumor metastasis. We identified zinc finger protein 191 (ZNF191) as a metastasis suppressor acting through DLG-YAP crosstalk in hepatocellular carcinoma (HCC). Overexpression of ZNF191 in HCC cells impaired cell motility, while ZNF191 depletion promoted cell migration in vitro and metastasis in vivo through triggering YAP signaling. Chromatin immunoprecipitation-sequencing revealed that ZNF191 specifically bound to the promoter of DLG1, a cell polarity maintainer and a negative regulator of YAP. The binding sequence of ZNF191 at the DLG1 promoter is a seven-repeat of TCAT motif. Double-knockdown experiments inferred that DLG1 was not only the mediator of the function of ZNF191 to suppress migration but also a link between ZNF191 and YAP signaling. Decreased expression of ZNF191 in human metastatic HCC specimens correlated positively with DLG1 levels but inversely with YAP activation. Our findings illustrate a YAP-targeting, antimetastasis function of ZNF191, thereby representing a possible prognostic marker and a potential target for metastasis therapy. CONCLUSION: ZNF191 directly binds to the DLG1 promoter at a typical TCAT repeating motif and activates the expression of DLG1; through up-regulating DLG1, ZNF191 inhibits cell migration and YAP activation in HCC cells and eventually inhibits metastasis. (Hepatology 2016;64:1148-1162).

Zinc finger transcription factor 191, directly binding to ß-catenin promoter, promotes cell proliferation of hepatocellular carcinoma.

UNLABELLED: Activation of ß-catenin, the central effector of the canonical wingless-type (Wnt) pathway, has been implicated in hepatocellular carcinoma (HCC). However, the transcription regulation mechanism of the ß-catenin gene in HCC remains unknown. Here we report that human zinc finger protein 191 (ZNF191) is a potential regulator of ß-catenin transcription. ZNF191, a Krüppel-like protein, specifically interacts with the TCAT motif, which constitutes the HUMTH01 microsatellite in the tyrosine hydroxylase (TH) gene ex vivo. We demonstrate that ZNF191 is significantly overexpressed in human HCC specimens and is associated with growth of human HCC cells. Global profiling of gene expression in ZNF191 knockdown human hepatic L02 cells revealed that the important Wnt signal pathway genes ß-catenin and cyclin D1 messenger RNAs (mRNAs) are significantly down-regulated. In agreement with transcription level, ß-catenin and cyclin D1 proteins are also down-regulated in transient and stable ZNF191 knockdown L02 and hepatoma Hep3B cell lines. Moreover, significant correlation between ZNF191 and ß-catenin mRNA expression was detected in human HCCs. Promoter luciferase assay indicated that ZNF191 can increase transcription activity of the full-length ß-catenin (CTNNB1) promoter, and nucleotide (nt)-1407/-907 of the CTNNB1 promoter exhibited the maximum transcriptional activity. Electrophoretic mobility shift assay showed that purified ZNF191 protein can directly bind to the CTNNB1 promoter, and the binding region is located at nt-1254/-1224. Finally, we demonstrate that the key binding sequence of ZNF191 in vivo is ATTAATT. CONCLUSION: ZNF191 can directly bind to the CTNNB1 promoter and activate the expression of ß-catenin and its downstream target genes such as cyclin D1 in hepatoma cell lines. This study uncovers a new molecular mechanism of transcription regulation of the ß-catenin gene in HCC.

FGFR4 and TGF-ß1 expression in hepatocellular carcinoma: correlation with clinicopathological features and prognosis.

OBJECTIVE: To investigate the expression and correlation of transforming growth factor-ß1 (TGF-ß1) and fibroblast growth factor receptor 4 (FGFR4) in human hepatocellular carcinoma (HCC) and the relationship with clinicopathological features and prognosis. MATERIALS AND METHODS: The expression of TGF-ß1 and FGFR4 in 126 HCC samples was detected immunohistochemically. Combined with clinical postoperative follow-up data, the expression of TGF-ß1 and FGFR4 in HCC and the relationship with the prognosis of patients were analyzed by statistically. RESULTS: The positive expression rate of TGF-ß1 was 84.1% (106/126) in tumors, and that in peritumoral liver tissues was 64.3% (81/126); the positive expression rate of FGFR4 in tumors was 74.6% (94/126) and that in peritumoral liver tissues was 57.1% (72/126). The expression of TGF-ß1 and FGFR4 in the carcinoma tissues was significantly higher than that in peritumoral liver tissues (p < 0.05). Intratumoral TGF-ß1 and FGFR4 expression was associated with TNM stage (p < 0.05). TGF-ß1 and FGFR4 expression levels didn't significantly correlate with other clinicopathological parameters, including age, sex, tumor size, serum AFP level, tumor differentiation, lymph node metastasis, etc. (p > 0.05). TGF-ß1 expression was positively correlated with FGFR4 expression (r = 0.595, p < 0.05). Patients with positive FGFR4 or TGF-ß1 expression had shorter overall survival compared with negative expression (p < 0.05). CONCLUSIONS: The expression of TGF-ß1 and FGFR4 could make synergy on the occurrence and progression of HCC, and may be used as prognosis indicators for HCC patients.

Cytotoxic T lymphocyte-dependent tumor growth inhibition by a vascular endothelial growth factor-superantigen conjugate.

T cells are major lymphocytes in the blood and passengers across the tumor vasculature. If these T cells are retained in the tumor site, a therapeutic potential will be gained by turning them into tumor-reactive cytotoxic T lymphocytes (CTLs). A fusion protein composed of human vascular endothelial growth factor (VEGF) and staphylococcal enterotoxin A (SEA) with a D227A mutation strongly repressed the growth of murine solid sarcoma 180 (S180) tumors (control versus VEGF-SEA treated with 15µg, mean tumor weight: 1.128g versus 0.252g, difference=0.876g). CD4(+) and CD8(+) T cells driven by VEGF-SEA were accumulated around VEGFR expressing tumor cells and the induced CTLs could release the tumoricidal cytokines, such as interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha). Meanwhile, intratumoral CTLs secreted cytolytic pore-forming perforin and granzyme B proteins around tumor cells, leading to the death of tumor cells. The labeled fusion proteins were gradually targeted to the tumor site in an imaging mice model. These results show that VEGF-SEA can serve as a tumor targeting agent and sequester active infiltrating CTLs into the tumor site to kill tumor cells, and could therefore be a potential therapeutical drug for a variety of cancers.

Apigenin enhances the cytotoxic effects of tumor necrosis factor-related apoptosis-inducing ligand in human rheumatoid arthritis fibroblast-like synoviocytes.

Activated rheumatoid arthritis (RA) fibroblast-like synoviocytes (RAFLSs) play a central role in both initiating and driving RA. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has been documented to induce apoptosis only in a small proportion of RAFLSs, which is followed by an induction of proliferation in surviving cells. Apigenin, a chemopreventive bioflavonoid, exhibits proapoptotic activity in many types of cells. In the present study, we sought to determine whether apigenin could enhance the cytotoxic effect of TRAIL on activated RAFLSs. Human RAFLSs isolated from patients with RA were treated with TRAIL (1 nM), apigenin (20 µM), or their combination, and subjected to apoptosis analysis after a 24-h incubation and proliferation analysis after a 72-h incubation. Apoptosis assay revealed that TRAIL or apigenin alone induced a marked apoptosis in RAFLS and their combination yielded a synergistic increase in RAFLS apoptosis. Immunoblotting analysis of apoptosis regulators demonstrated that combined treatment with apigenin increased caspase-3 expression and activity and decreased the Bcl-2/Bax ratio relative to treatment with TRAIL alone. The presence of apigenin significantly restrained TRAIL-induced RAFLS proliferation, coupled with restoration of the expression of two cell-cycle inhibitors p21 and p27. Moreover, the combination with apigenin blunted TRAIL-induced activation of the phosphatidylinositol 3-kinase (PI3-K)/Akt pathway. Our data collectively demonstrate that apigenin sensitizes RAFLS to TRAIL-induced apoptosis and counteracts TRAIL-dependent RAFLS proliferation, which is likely mediated through inactivation of PI3-K/Akt signaling pathway.

Carbonyl reductase 1 as a novel target of (-)-epigallocatechin gallate against hepatocellular carcinoma.

UNLABELLED: Human carbonyl reductase 1 (CBR1) converts the antitumor drug and anthracycline daunorubicin (DNR) into the alcohol metabolite daunorubicinol (DNROL) with significantly reduced antitumor activity and cardiotoxicity, and this limits the clinical use of DNR. Inhibition of CBR1 can thus increase the efficacy and decrease the toxicity of DNR. Here we report that (-)-epigallocatechin gallate (EGCG) from green tea is a promising inhibitor of CBR1. EGCG directly interacts with CBR1 and acts as a noncompetitive inhibitor with respect to the cofactor reduced nicotinamide adenine dinucleotide phosphate and the substrate isatin. The inhibition is dependent on the pH, and the gallate moiety of EGCG is required for activity. Molecular modeling has revealed that EGCG occupies the active site of CBR1. Furthermore, EGCG specifically enhanced the antitumor activity of DNR against hepatocellular carcinoma SMMC7721 cells expressing high levels of CBR1 and corresponding xenografts. We also demonstrated that EGCG could overcome the resistance to DNR by Hep3B cells stably expressing CBR1 but not by RNA interference of CBR1-HepG2 cells. The level of the metabolite DNROL was negatively correlated with that of EGCG in the cell extracts. Finally, EGCG decreased the cardiotoxicity of DNR in a human carcinoma xenograft model with both SMMC7721 and Hep3B cells in mice. CONCLUSION: These results strongly suggest that EGCG can inhibit CBR1 activity and enhance the effectiveness and decrease the cardiotoxicity of the anticancer drug DNR. These findings also indicate that a combination of EGCG and DNR might represent a novel approach for hepatocellular carcinoma therapy or chemoprevention.

[Research progresses on septin family].

The septins are a family of proteins that are broadly distributed in almost all of eukaryotes except plants. septin was first identified in yeast as a protein that played a role in cytokinesis. With the recent advances in the field, the functions of these proteins become diverse in many organisms. In particular, the number of known mammalian septin family members has increased dramatically. They are now known to have many cellular roles such as cytokinesis, polarity determination, vesicle trafficking and membrane dynamics. Recently, more and more data suggest that some septin family members participate in the pathogenesis of different diseases including neoplasia, neurodegeneration and infections. These make the research of septins a hallmark in cell biology and pathology. In this review, we will summarize the major research progresses about septins in their classification, structure, biological function and the relationship with human diseases.

Pyramidatine (Z88) Sensitizes Vincristine-Resistant Human Oral Cancer (KB/VCR) Cells to Chemotherapeutic Agents by Inhibition of P-glycoprotein.

BACKGROUND: Multi-drug resistance (MDR) remains a major impediment in cancer therapy. A major goal for scientists is to discover more effective compounds that are able to circumvent MDR and simultaneously have minimal adverse side effects. OBJECTIVE: In the present study, we aim to determine the anti-MDR effects of pyramidatine (Z88), a cinnamic acid-derived bisamide compound isolated from the leaves of Aglaia perviridis, on KB/VCR (vincristineresistant human oral cancer cells) and MCF-7/ADR (adriamycin-resistant human breast adenocarcinoma) cells. METHODS: Cell viability and average resistant fold (RF) of Z88 were examined by Cell Counting Kit-8 (CCK-8) assay. Flow cytometry, western blot, RT-PCR, Rhodamine 123 accumulation assay and P-glycoprotein (P-gp) ATPase assay were used to demonstrate the anti-MDR activity and mechanism of Z88. RESULTS: The average RF of Z88 is 0.09 and 0.51 in KB/VCR and MCF-7/ADR cells. A CCK-8 assay showed that Z88 could enhance the cytotoxicity of VCR toward KB/VCR cells. A FACS analysis revealed that Z88 could enhance the VCR-induced apoptosis as well as G2/M arrest in a dose-dependent manner in KB/VCR cells. Western blot results showed that the expression levels of PARP, Bax, and cyclin B1 all increased after treatment with 0.2 µmol/L (µM) of VCR combined with 10 µM of Z88 for 24 h in KB/VCR cells. Z88 also could enhance the accumulation of rhodamine 123. Further studies showed that Z88 could inhibit the verapamil stimulated Pgp ATPase activity. Additionally, qPCR detection and western blot assays revealed that Z88 could decrease the expression of P-gp at both RNA and protein level. CONCLUSION: Z88 exerted potent anti-MDR activity in vitro and its mechanisms are associated with dualinhibition of the function and expression of P-gp. These findings encourage efforts to develop more effective reversal agents to circumvent MDR based on Z88.

Knockout of the Nogo-B Gene Attenuates Tumor Growth and Metastasis in Hepatocellular Carcinoma.

Human hepatocellular carcinoma (HCC) is a malignant cancer. It is a challenge to develop anti-HCC drugs due to HCC's extreme aggressiveness and with the sensitivity of the liver to show severe adverse effects. More importantly, the precise mechanisms causing HCC pathogenicity are not known. Our previous study disclosed Nogo-B as a reticulon 4 (Rtn4) family member. In the present study, we first identified that Nogo-B played a critical role in HCC progression. We found, via in vitro and in vivo assays, that Nogo-B was expressed aberrantly in primary HCC tumor tissues and immortal HCC cells but was relatively scarce in the normal liver tissues or cells. Nogo-B knockout, via the CRISPR-Cas9 technique, resulted in significant suppression of HCC cell proliferation and tumor growth. Next-generation sequencing analysis showed that Nogo-B knockout have effects on interleukin-6 (IL-6) signaling pathway. Furthermore, we observed that IL-6 induced phosphorylation of STAT3 (pSTAT3) in wild-type HCC cells, but Nogo-B knockout could reduce IL-6-induced increase of pSTAT3, supporting that Nogo-B affects HCC tumor progression possibly via regulating the IL-6/STAT3 signaling pathway. In conclusion, Nogo-B is expressed aberrantly in HCCs and plays an oncogenic role. These findings support that Nogo-B may be a novel anti-HCC therapeutic target.

UNC50 prompts G1/S transition and proliferation in HCC by regulation of epidermal growth factor receptor trafficking.

BACKGROUND: UNC50 has long been recognized as a Golgi apparatus protein in yeast, and is involved in nicotinic receptor trafficking in Caenorhabditis elegans, but little is known about UNC50 gene function in human biology despite it being conserved from yeast to high eukaryotes. OBJECTIVES: We investigated the relation between UNC50 and human hepatocellular carcinoma (HCC) and the potential mechanisms underlying HCC development. METHODS: UNC50 mRNA expression patterns in 12 HCC and adjacent non-cancerous tissues determined using northern blotting were confirmed by real-time PCR in another 44 paired tissues. Microarray experiments were used to screen for global effects of UNC50 knockdown in the Hep3B cell line, and were confirmed by real-time PCR, western blotting, flow cytometry, and tetrazolium assay in both UNC50 overexpression and knockdown Hep3B cells. RESULTS: UNC50 expression levels were upregulated in HCC tissues in comparison with the adjacent non-cancerous tissues. UNC50 knockdown reduced mRNA levels of the downstream targets of the epidermal growth factor receptor (EGFR) pathway: cyclin D1 (CCND1), EGF, matrix metalloproteinase-7 (MMP7), aldose reductase-like 1 (AKR1B10), cell surface-associated mucin 1 (MUC1), and gastrin (GAST). Moreover, UNC50 influenced EGF, inducing cell cycle entry by affecting cell surface EGFR amounts. CONCLUSIONS: UNC50 may plays some roles in HCC progression by affecting the EGFR pathway.

Cyclophilin J is a novel peptidyl-prolyl isomerase and target for repressing the growth of hepatocellular carcinoma.

Cyclophilin J (CYPJ) is a new member of the peptidyl-prolyl cis/trans-isomerase (PPIase) identified with upregulated expression in human glioma. However, the biological function of CYPJ remained unclear. We aimed to study the role of CYPJ in hepatocellular carcinoma (HCC) carcinogenesis and its therapeutic potential. We determined the expression of CYPJ in HCC/adjacent normal tissues using Western blot, Northern blot and semi-quantitative RT-PCR, analyzed the biochemical characteristics of CYPJ, and resolved the 3D-structure of CYPJ/Cyclosporin A (CsA) complex. We also studied the roles of CYPJ in cell cycle, cyclin D1 regulation, in vitro and in vivo tumor growth. We found that CYPJ expression was upregulated in over 60% HCC tissues. The PPIase activity of CYPJ could be inhibited by the widely used immunosuppressive drug CsA. CYPJ was found expressed in the whole cell of HCC with preferential location at the cell nucleus. CYPJ promoted the transition of cells from G1 phase to S phase in a PPIase-dependent manner by activating cyclin D1 promoter. CYPJ overexpression accelerated liver cell growth in vitro (cell growth assay, colony formation) and in vivo (xenograft tumor formation). Inhibition of CYPJ by its inhibitor CsA or CYPJ-specific RNAi diminished the growth of liver cancer cells in vitro and in vivo. In conclusion, CYPJ could facilitate HCC growth by promoting cell cycle transition from G1 to S phase through the upregulation of cyclin D1. Suppression of CYPJ could repress the growth of HCC, which makes CYPJ a potential target for the development of new strategies to treat this malignancy.

Studies on the beta(l-4)Galactosyltransferase of Cell Surface in Induced HL60 Cells.

A fluorescene assay method for beta(1-4) galactosyltransferase (beta1-4GT) of cell surface has been developed using a pyridylaminated sugar as an acceptor substrate. A fluorescent sugar chain, whose reducing end of the Gnbeta1-2Malpha1-6(Gnbeta1-2Malpha1-3) Mbeta1-4Gnbeta1-4(Fucalpha1-6) Gn has been aminated with 2-aminopyridine. beta1-4GT activity of cell surface varied in different stages of the cell cycle with the highest activity at interphase. The enzyme activity of cell surface took a change when HL60 cell line was induced to differentiate by PMA or RA. The cell surface enzyme activity was 1.30 times as much as tile control group at 24 h in the case of PMA induction, and a maximum increase of 70% over the control on the third day with RA induction.

Studies on the Method for the Determination of beta1-4 Galactosyltransferase and Its Kinetics.

A fluorescence assay method for beta1-4galactosyltransferase (beta1-4GT) has been developed involving a pyridylaminated sugar as an acceptor substrate, a fluorescent sugar chain, with the reducing end of the Gnbeta1 - 2Malpha1 - 6(Gnbeta1-2Malpha1-3)Mbeta1 - 4Gnbeta1 - 4Gn - PA aminated with 2-aminopyridine. Microsome was prepared from the liver of normal male rats as an enzyme sample. Then the fluorescent reaction product was separated by reverse-phase HPLC. The kinetic experiments were carried out using crude enzyme extracts of the Golgi complex from the rat liver. The enzyme has a pH optimum of 6.5,and optimal concentration of Triton X-100 of 0.5%. The K(m) and V(max) values for the sugar acceptor substrates were found to be 2.31x10(-3)M(-1) and 5.75x10(-2) &mgr;mol/(min.mg) respectively. Furthermore, our research revealed that beta1-4GT had branch specificity. The Gn of alpha1-3 mannose branch of the acceptor substrate was more susceptible to galactosylation than that of the alpha1-6 branch by 2.10 times.

Changes in gene expression profiles of the hip joint ligament of patients with ankylosing spondylitis revealed by DNA chip.

To investigate the pathogenesis of abnormal ossification of the hip ligament in patients with ankylosing spondylitis (AS) by comparing gene expression profiles of the hip ligament in patients with AS to those in normal persons using DNA microarray technology, we studied 18 patients with AS (case group) who underwent total hip arthroplasty in our department from March 1, 2009 to January 31, 2010 and compared them with 6 patients with femoral neck fracture (control group) who underwent total hip replacement. We screened the first five patients in each group with the HumanWG-6 v3.0 Expression BeadChip. Compared to the control group, 519 genes in the case group showed statistically significant differences. Among these, there were 238 upregulated genes and 196 downregulated genes. Gene Ontology (GO) classification showed that differential genes in the hip joint ligaments of patients with AS were involved in immunity, cell adhesion, membrane transport, sugar metabolism, polysaccharide synthesis and metabolism, and cell motility. The Kyoto Encyclopedia of Genes and Genomes classification showed that these differential genes were involved in B cell receptor signaling pathways, adherens junction, protein export, fructose and mannose metabolism, T cell receptor signaling pathways, keratin sulfate biosynthesis, N-glycan biosynthesis, and regulation of the actin cytoskeleton. We tested 2 genes from the screened differential genes in 18 case patients and 6 control cases using real-time polymerase chain reaction. The results demonstrated that the expression of the B4GALT3 gene in the case group was 15.32 times higher than that in the control group (P < 0.01), and the expression of the RBP5 gene in the case group was 4.09 times higher than that in the control group (P < 0.01). This conformed to the microarray analysis. Our preliminary data suggest that differential gene expression in patients with AS includes the immune system, intracellular or extracellular signaling pathway, and bone matrix biosynthesis pathway, which might play important roles in hip joint ligament ossification.

Effects of berberine on human rheumatoid arthritis fibroblast-like synoviocytes.

Activated rheumatoid arthritis fibroblast-like synoviocytes (RAFLSs) play an important role in the initiation and progression of rheumatoid arthritis (RA). Rapid proliferation and defective apoptosis of RAFLSs are two main mechanisms contributing to synovial hyperplasia. Berberine, the major constituent of Coptidis Rhizoma, has been widely used as an antitumor and anti-inflammation agent. Here we show that berberine significantly inhibited cell proliferation of serum-starved human RAFLSs in a dose-dependent manner. Cell cycle analysis of berberine-treated RAFLSs indicated a cell cycle arrest at the G0/G1 phase. The inhibitory effects of berberine correlated with an induction of cyclin-dependent kinase (CDK) inhibitors Cip1/p21 and Kip1/p27 and a reduction of CDK2, CDK4 and CDK6, and cyclins D1, D2 and E. Furthermore, an apoptosis assay showed that berberine treatment increased apoptotic death of RAFLSs, which was associated with an increased expression of proapoptotic protein Bax and decreased expression of antiapoptotic proteins Bcl-2 and Bcl-xl, disruption of mitochondrial membrane potential, and activation of caspase-3, caspase-9 and poly (ADP-ribose) polymerase. Taken together, these results demonstrate that berberine exerts antiproliferative effects against RAFLSs, likely through deregulation of numerous cell cycle and apoptosis regulators, thus having potential therapeutic implications in the treatment of RA.

Characterization and expression of HLysG2, a basic goose-type lysozyme from the human eye and testis.

Lysozyme plays an important role in human innate immunity by causing bacterial cell lysis. We describe for the first time, the actual performance of human lysozyme g-like 2 (HLysG2), a mammalian g-type lysozyme. RT-PCR revealed that the HLysG2 gene was transcribed in eye and testis tissues. A spot was detected from human tears using 2D gel electrophoresis and was identified as HLysG2 using MALDI-TOF/TOF MS and a MASCOT search with a matching score of 140 and 27% sequence coverage of the whole amino acid sequence. To gain insight into the in vitro antimicrobial activities of HLysG2, the mature peptide-coding region was cloned into Pichia pastoris for heterogeneous expression. Recombinant HLysG2, had an optimal at pH 6.0 and 30 °C, reached the peak activity of 1.2 × 10(4)U/mg at the sodium ion concentration of 75 mM and showed a higher salt tolerance than human c-type lysozyme (HLysC). Recombinant HlysG2 inhibited Gram-positive bacterial growth and did not inhibit Gram-negative bacterial and Candida albicans growth. Results indicated that HLysG2 is a potent antibacterial protein that may play a role in the innate immunity of the human eye.

Glycosyltransferase mechanisms: impact of a 5-fluoro substituent in acceptor and donor substrates on catalysis.

In glycosyltransferase-catalyzed reactions a new carbohydrate-carbohydrate bond is formed between a carbohydrate acceptor and the carbohydrate moiety of either a sugar nucleotide donor or lipid-linked saccharide donor. It is currently believed that most glycosyltransferase-catalyzed reactions occur via an electrophilic activation mechanism with the formation of an oxocarbenium ion-like transition state, a hypothesis that makes clear predictions regarding the charge development on the donor (strong positive charge) and acceptor (minimal negative charge) substrates. To better understand the mechanism of these enzyme-catalyzed reactions, we have introduced a strongly electron-withdrawing group (fluorine) at C-5 of both donor and acceptor substrates in order to explore its effect on catalysis. In particular, we have investigated the effects of the 5-fluoro analogues on the kinetics of two glycosyltransferase-catalyzed reactions mediated by UDP-GlcNAc:GlcNAc-P-P-Dol N-acetylglucosaminyltransferase (chitobiosyl-P-P-lipid synthase, CLS) and beta-N-acetylglucosaminyl-beta-1,4 galactosyltransferase (GalT). The 5-fluoro group has a marked effect on catalysis when inserted into the UDP-GlcNAc donor, with the UDP(5-F)-GlcNAc serving as a competitive inhibitor of CLS rather than a substrate. The (5-F)-GlcNAc beta-octyl glycoside acceptor, however, is an excellent substrate for GalT. Both of these results support a weakly associative transition state for glycosyltransferase-catalyzed reactions that proceed with inversion of configuration.

Survivin mutant (Surv-DD70, 71AA) disrupts the interaction of Survivin with Aurora B and causes multinucleation in HeLa cells.

Survivin is associated with Aurora B, inner centromere protein (INCENP), and borealin to form a chromosomal passenger complex that plays multiple roles during cell division. We used mutational analysis to study interaction of Survivin with Aurora B and the effect of this interaction on cell division. A Survivin mutant with the terminal domain deleted (Survivin 1-107) bound Aurora B as efficiently as Survivin wild type. This indicated that the proximal BIR domain of Survivin was responsible for Survivin binding to Aurora B. Survivin mutants (Surv-R18A, Surv-D53A, and Sur-KK78, and 79AA) all bound to Aurora B efficiently, but mutation in the conserved amino acid residues of the acidic patch on Survivin (Surv-DD70, 71AA) abolished the direct interaction of Survivin and Aurora B. The Survivin mutant (Surv-DD70, 71AA) localized diffusely in metaphase and failed to successfully accumulate in the midbody during cytokinesis. Furthermore, over-expression of the Survivin mutant (Surv-DD70, 71AA) severely disturbed cytokinesis, resulting in multinucleation in HeLa cell. This indicated that the direct interaction of Survivin and Aurora B was critical for the correct location of Survivin and the function of the Survivin complex in cell division.

Identification and characterization of a cDNA encoding a dolichyl pyrophosphate phosphatase located in the endoplasmic reticulum of mammalian cells.

The CWH8 gene in Saccharomyces cerevisiae has been shown recently (Fernandez, F., Rush, J. S., Toke, D. A., Han, G., Quinn, J. E., Carman, G. M., Choi, J.-Y., Voelker, D. R., Aebi, M., and Waechter, C. J. (2001) J. Biol. Chem. 276, 41455-41464) to encode a dolichyl pyrophosphate (Dol-P-P) phosphatase associated with crude microsomal fractions. Mutations in CWH8 result in the accumulation of Dol-P-P, deficiency in lipid intermediate synthesis, defective protein N-glycosylation, and a reduced growth rate. A cDNA (DOLPP1, GenBank accession number AB030189) from mouse brain encoding a homologue of the yeast CWH8 gene is now shown to complement the defects in growth and protein N-glycosylation, and to correct the accumulation of Dol-P-P in the cwh8Delta yeast mutant. Northern blot analyses demonstrate a wide distribution of the DOLPP1 mRNA in mouse tissues. Overexpression of Dolpp1p in yeast, COS, and Sf9 cells produces substantial increases in Dol-P-P phosphatase activity but not in dolichyl monophosphate or phosphatidic acid phosphatase activities in microsomal fractions. Subcellular fractionation and immunofluorescence studies localize the enzyme encoded by DOLPP1 to the endoplasmic reticulum of COS cells. The results of protease sensitivity studies with microsomal vesicles from the lpp1Delta/dpp1Delta yeast mutant expressing DOLPP1 are consistent with Dolpp1p having a luminally oriented active site. The sequence of the DOLPP1 cDNA predicts a polypeptide with 238 amino acids, and a new polypeptide corresponding to 27 kDa is observed when DOLPP1 is expressed in yeast, COS, and Sf9 cells. This study is the first identification and characterization of a cDNA clone encoding an essential component of a mammalian lipid pyrophosphate phosphatase that is highly specific for Dol-P-P. The specificity, subcellular location, and topological orientation of the active site described in the current study strongly support a role for Dolpp1p in the recycling of Dol-P-P discharged during protein N-glycosylation reactions on the luminal leaflet of the endoplasmic reticulum in mammalian cells.