Quantitative and reversible lectin-induced association of gold nanoparticles modified with alpha-lactosyl-omega-mercapto-poly(ethylene glycol)

Gold nanoparticles (1-10 nm size range) were prepared with an appreciably narrow size distribution by in situ reduction of HAuCl(4) in the presence of heterobifunctional poly(ethylene glycol) (PEG) derivatives containing both mercapto and acetal groups (alpha-acetal-omega-mercapto-PEG). The alpha-acetal-PEG layers formed on gold nanoparticles impart appreciable stability to the nanoparticles in aqueous solutions with elevated ionic strength and also in serum-containing medium. The PEG acetal terminal group was converted to aldehyde by gentle acid treatment, followed by the reaction with p-aminophenyl-beta-D- lactopyranoside (Lac) in the presence of (CH(3))(2)NHBH(3). Lac-conjugated gold nanoparticles exhibited selective aggregation when exposed to Recinus communis agglutinin (RCA(120)), a bivalent lectin specifically recognizing the beta-D-galactose residue, inducing significant changes in the absorption spectrum with concomitant visible color change from pinkish-red to purple. Aggregation of the Lac-functionalized gold nanoparticles by the RCA(120) lectin was reversible, recovering the original dispersed phase and color by addition of excess galactose. Further, the degree of aggregation was proportional to lectin concentration, allowing the system to be utilized to quantitate lectin concentration with nearly the same sensitivity as ELISA. This simple, yet highly effective, derivatization of gold nanoparticles with heterobifunctional PEG provides a convenient method to construct various colloidal sensor systems currently applied in bioassays and biorecognition.

DNA methylation patterns in hereditary human cancers mimic sporadic tumorigenesis

Cancer cells have aberrant patterns of DNA methylation including hypermethylation of gene promoter CpG islands and global demethylation of the genome. Genes that cause familial cancer, as well as other genes, can be silenced by promoter hypermethylation in sporadic tumors, but the methylation of these genes in tumors from kindreds with inherited cancer syndromes has not been well characterized. Here, we examine CpG island methylation of 10 genes (hMLH1, BRCA1, APC, LKB1, CDH1, p16(INK4a), p14(ARF), MGMT, GSTP1 and RARbeta2) and 5-methylcytosine DNA content, in inherited (n = 342) and non-inherited (n = 215) breast and colorectal cancers. Our results show that singly retained alleles of germline mutated genes are never hypermethylated in inherited tumors. However, this epigenetic change is a frequent second "hit", associated with the wild-type copy of these genes in inherited tumors where both alleles are retained. Global hypomethylation was similar between sporadic and hereditary cases, but distinct differences existed in patterns of methylation at non-familial genes. This study demonstrates that hereditary cancers "mimic" the DNA methylation patterns present in the sporadic tumors.

Annual change in pulmonary function and clinical phenotype in chronic obstructive pulmonary disease

RATIONALE

Although the rate of annual decline in FEV1 is one of the most important outcome measures in chronic obstructive pulmonary disease (COPD), little is known about intersubject variability based on clinical phenotypes.

OBJECTIVES

To examine the intersubject variability in a 5-year observational cohort study, particularly focusing on emphysema severity.

METHODS

A total of 279 eligible patients with COPD (stages I-IV: 26, 45, 24, and 5%) participated. We conducted a detailed assessment of pulmonary function and computed tomography (CT) at baseline, and performed spirometry every 6 months before and after inhalation of bronchodilator. Smoking status, exacerbation, and pharmacotherapy were carefully monitored. Emphysema severity was evaluated by CT and annual measurements of carbon monoxide transfer coefficient.

MEASUREMENTS AND MAIN RESULTS

Using mixed effects model analysis, the annual decline in post-bronchodilator FEV1 was -32±24 (SD) ml/yr (n=261). We classified the subjects of less than the 25th percentile as Rapid decliners, the 25th to 75th percentile as Slow decliners, and greater than the 75th percentile as Sustainers (-63±2, -31±1, and -2±1 [SE] ml/yr). Emphysema severity, but not %FEV1, showed significant differences among the three groups. Multiple logistic regression analysis demonstrated that the Rapid decliners were independently associated with emphysema severity assessed either by CT or carbon monoxide transfer coefficient. The Sustainers displayed less emphysema and higher levels of circulating eosinophils.

CONCLUSIONS

Emphysema severity is independently associated with a rapid annual decline in FEV1 in COPD. Sustainers and Rapid decliners warrant specific attention in clinical practice.

Novel combretastatin analogues effective against murine solid tumors: design and structure-activity relationships

A series of combretastatin A-4 (CA-4) analogues were synthesized, and their cytotoxic effects against murine Colon 26 adenocarcinoma and inhibitory activity on tubulin polymerization were evaluated. Since CA-4 has limited aqueous solubility, the target compounds were designed to improve solubility by introduction of a nitrogen-containing group. Among the compounds synthesized, those with an amino moiety in place of the phenolic OH of CA-4 showed potent antitubulin activity and cytotoxicity against murine Colon 26 adenocarcinoma in vitro. Some of the compounds which were potent in vitro were evaluated in the murine tumor model Colon 26 in vivo. Among these, 13bHCl, 21aHCl, and 21bHCl showed significant antitumor activity in the animal model, while CA-4 was ineffective. 13bHCl and 21aHCl were further evaluated in two murine tumor models (Colon 38 and 3LL) and human xenografts HCT-15. These compounds showed potent antitumor activity comparable or superior to that of CDDP. The structure-activity relationships of this series of compounds are also discussed.

Transplantation of clonal neural precursor cells derived from adult human brain establishes functional peripheral myelin in the rat spinal cord

We examined the myelin repair potential of transplanted neural precursor cells derived from the adult human brain from tissue removed during surgery. Sections of removed brain indicated that nestin-positive cells were found predominantly in the subventricular zone around the anterior horns of the lateral ventricle and in the dentate nucleus. Neurospheres were established and the nestin-positive cells were clonally expanded in EGF and bFGF. Upon mitogen withdrawal in vitro, the cells differentiated into neuron- and glia-like cells as distinguished by antigenic profiles; the majority of cells in culture showed neuronal and astrocytic properties with a small number of cells showing properties of oligodendrocytes and Schwann cells. When transplanted into the demyelinated adult rat spinal cord immediately upon mitogen withdrawal, the cells elicited extensive remyelination with a peripheral myelin pattern similar to Schwann cell myelination characterized by large cytoplasmic and nuclear regions, a basement membrane, and P0 immunoreactivity. The remyelinated axons conducted impulses at near normal conduction velocities. This suggests that a common neural progenitor cell for CNS and PNS previously described for embryonic neuroepithelial cells may be present in the adult human brain and that transplantation of these cells into the demyelinated spinal cord results in functional remyelination.

Identification and characterization of an Escherichia coli gene required for the formation of correctly folded alkaline phosphatase, a periplasmic enzyme

Tn5 insertion mutations of Escherichia coli were isolated that impaired the formation of correctly folded alkaline phosphatase (PhoA) in the periplasm. The PhoA polypeptide synthesized in the mutants was translocated across the cytoplasmic membrane but not released into the periplasmic space. It was susceptible to degradation by proteases in vivo and in vitro. The wild-type counterpart of this gene (named ppfA) has been sequenced and shown to encode a periplasmic protein with a pair of potentially redox-active cysteine residues. PhoA synthesized in the mutants indeed lacked disulfide bridges. These results indicate that the folding of PhoA in vivo is not spontaneous but catalyzed at least at the disulfide bond formation step.

Effects of mutations in heat-shock genes groES and groEL on protein export in Escherichia coli

Escherichia coli heat-shock proteins GroES and GroEL are essential cytoplasmic proteins, which have been termed 'chaperonins' because of their ability to assist protein assembly of bacteriophage capsids and multimeric enzymes of foreign origin. In this report we show that temperature-sensitive mutations in groES and groEL genes cause defective export of the plasmid-encoded beta-lactamase (Bla) in vivo. Since efficient translocation of proteins across biological membranes is thought to be supported by cytoplasmic factors that protect presecretory molecules from being misfolded, these results suggest that both GroES and GroEL proteins possess a chaperone function by which they facilitate export of Bla. The translocation of other secretory proteins, however, appears to depend minimally on GroE, suggesting that GroE interacts only with a specific class of secreted proteins.

FtsH is required for proteolytic elimination of uncomplexed forms of SecY, an essential protein translocase subunit

When secY is overexpressed over secE or secE is underexpressed, a fraction of SecY protein is rapidly degraded in vivo. This proteolysis was unaffected in previously described protease-defective mutants examined. We found, however, that some mutations in ftsH, encoding a membrane protein that belongs to the AAA (ATPase associated with a variety of cellular activities) family, stabilized oversynthesized SecY. This stabilization was due to a loss of FtsH function, and overproduction of the wild-type FtsH protein accelerated the degradation. The ftsH mutations also suppressed, by alleviating proteolysis of an altered form of SecY, the temperature sensitivity of the secY24 mutation, which alters SecY such that its interaction with SecE is weakened and it is destabilized at 42 degrees C. We were able to isolate a number of additional mutants with decreased ftsH expression or with an altered form of FtsH using selection/screening based on suppression of secY24 and stabilization of oversynthesized SecY. These results indicate that FtsH is required for degradation of SecY. Overproduction of SecY in the ftsH mutant cells proved to deleteriously affect cell growth and protein export, suggesting that elimination of uncomplexed SecY is important for optimum protein translocation and for the integrity of the membrane. The primary role of FtsH is discussed in light of the quite pleiotropic mutational effects, which now include stabilization of uncomplexed SecY.

Topology analysis of the SecY protein, an integral membrane protein involved in protein export in Escherichia coli

The secY (prlA) gene product is an essential component of the Escherichia coli cytoplasmic membrane, and its function is required for the translocation of exocytoplasmic proteins across the membrane. We have analyzed the orientation of the SecY protein in the membrane by examining the hydropathic character of its amino acid sequence, by testing its susceptibility to proteases added to each side of the membrane, and by characterizing SecY-PhoA (alkaline phosphatase) hybrid proteins constructed by TnphoA transpositions. The orientation of the PhoA portion of the hybrid protein with respect to the membrane was inferred from its enzymatic activity as well as sensitivity to external proteases. The results suggest that SecY contains 10 transmembrane segments, five periplasmically exposed parts, and six cytoplasmic regions including the amino- and carboxyterminal regions.

SOX2 is frequently downregulated in gastric cancers and inhibits cell growth through cell-cycle arrest and apoptosis

SOX transcription factors are essential for embryonic development and play critical roles in cell fate determination, differentiation and proliferation. We previously reported that the SOX2 protein is expressed in normal gastric mucosae but downregulated in some human gastric carcinomas. To clarify the roles of SOX2 in gastric carcinogenesis, we carried out functional characterisation of SOX2 in gastric epithelial cell lines. Exogenous expression of SOX2 suppressed cell proliferation in gastric epithelial cell lines. Flow cytometry analysis revealed that SOX2-overexpressing cells exhibited cell-cycle arrest and apoptosis. We found that SOX2-mediated cell-cycle arrest was associated with decreased levels of cyclin D1 and phosphorylated Rb, and an increased p27^Kip1 level. These cells exhibited further characteristics of apoptosis, such as DNA laddering and caspase-3 activation. SOX2 hypermethylation signals were observed in some cultured and primary gastric cancers with no or weak SOX2 expression. Among the 52 patients with advanced gastric cancers, those with cancers showing SOX2 methylation had a significantly shorter survival time than those without this methylation (P=0.0062). Hence, SOX2 plays important roles in growth inhibition through cell-cycle arrest and apoptosis in gastric epithelial cells, and the loss of SOX2 expression may be related to gastric carcinogenesis and poor prognosis.

Syntheses and antitumor activity of cis-restricted combretastatins: 5-membered heterocyclic analogues

A series of cis-restricted combretastatin analogues with 5-membered heterocycles were synthesized and their inhibitory activity against microtubule assembly and cytotoxic activity against the colon 26 adenocarcinoma cancer cell line were evaluated. Some of the heterocyclic analogues showed potent antitubulin activity and cytotoxicity. Compounds 16 and 35 showed marked tumor growth suppression in the colon 26 murine tumor model.

The gcm-motif: a novel DNA-binding motif conserved in Drosophila and mammals

In the Drosophila nervous system, the glial cells missing gene (gcm) is transiently expressed in glial precursors to switch their fate from the neuronal default to glia. It encodes a novel 504-amino acid protein with a nuclear localization signal. We report here that the GCM protein is a novel DNA-binding protein and that its DNA-binding activity is localized in the N-terminal 181 amino acids. It binds with high specificity to the nucleotide sequence, (A/G)CCCGCAT, which is a novel sequence among known targets of DNA-binding proteins. Eleven such GCM-binding sequences are found in the 5' upstream region of the repo gene, whose expression in early glial cells is dependent on gcm. This suggests that the GCM protein is a transcriptional regulator directly controlling repo. We have also identified homologous genes from human and mouse whose products share a highly conserved N-terminal region with Drosophila GCM. At least one of these was shown to have DNA-binding activity similar to that of GCM. By comparing the deduced amino acid sequences of these gene products, we were able to define the "gcm motif," an evolutionarily conserved motif with DNA-binding activity. By PCR amplification, we obtained evidence for the existence of additional gcm-motif genes in mouse as well as in Drosophila. The gcm-motif, therefore, forms a family of novel DNA-binding proteins, and may function in various aspects of cell fate determination.

Recombinant human interleukin 6 (B-cell stimulatory factor 2) is a potent inducer of differentiation of mouse myeloid leukemia cells (M1)

Recombinant human interleukin 6 (IL-6), a lymphokine involved in the final differentiation of activated B-cells into antibody-forming cells, greatly suppressed proliferation and induced differentiation of murine myeloid leukemia cells (M1) into mature macrophage-like cells. When M1 cells were treated with IL-6, their growth was completely arrested as early as on day 2, and they were induced to differentiate morphologically into macrophage-like cells. Differentiation-associated properties such as phagocytic activity, adherence to the dish surface, Fc and C3 receptors, were also induced within 24 h by IL-6, and they reached their respective maximal levels on day 2 or 3. The potency of IL-6 in suppressing proliferation and inducing differentiation was much greater than that of 1 alpha,25-dihydroxyvitamin D3 one of the most potent inducers of M1 cells. The present report indicates that IL-6 is involved in the differentiation of not only B-cells but also myeloid leukemia cells.

Expression of SR-PSOX, a novel cell-surface scavenger receptor for phosphatidylserine and oxidized LDL in human atherosclerotic lesions

Receptor-mediated endocytosis of oxidized low density lipoprotein (Ox-LDL) by macrophages and the subsequent foam cell transformation in the arterial intima are key events in early atherogenesis. Recently, we have identified a novel macrophage cell-surface receptor for Ox-LDL by expression cloning from a cDNA library of phorbol 12-myristate 13-acetate-stimulated THP-1 cells, designated as the scavenger receptor for phosphatidylserine and oxidized lipoprotein (SR-PSOX). Here, we examined SR-PSOX expression in human atherosclerotic lesions. Total cellular RNA and fresh frozen sections were prepared from human carotid endarterectomy specimens (from 21 patients) and directional coronary atherectomy specimens (from 11 patients). Fragments of human aortas of 2 patients without visible atherosclerotic lesions served as negative controls. Quantitative reverse transcription-polymerase chain reaction demonstrated that SR-PSOX mRNA expression was prominent in atherosclerotic lesions but undetectable in normal aortas. Immunohistochemistry showed that SR-PSOX was predominantly expressed by lipid-laden macrophages in the intima of atherosclerotic plaques in carotid endarterectomy and directional coronary atherectomy specimens, although its expression was not detectable in normal arterial wall. Double-labeled immunohistochemistry confirmed that SR-PSOX is expressed by intimal macrophages. Taken together, SR-PSOX may be involved in Ox-LDL uptake and subsequent foam cell transformation in macrophages in vivo and thus may play important roles in human atherosclerotic lesion formation.

The inhibitory effect of vitamin K2 (menatetrenone) on bone resorption may be related to its side chain

Although the effects of vitamin K2 and vitamin K1 on bone metabolism have been reported, the difference between them has not been investigated. We now show the effects of menatetrenone, one of the vitamin K2 homologues, and vitamin K1 on bone resorption. Menatetrenone at greater than 3 x 10(-6) M significantly inhibited the calcium release from mouse calvaria induced by 3 x 10(-10) M of 1,25(OH)2D3 or 10(-7) M of prostaglandin E2, and it also inhibited osteoclast-like multinucleated cell (MNC) formation induced by 10(-8) M of 1,25(OH)2D3 in co-culture of spleen cells and stromal cells at the same concentrations. In contrast, the same doses of vitamin K1 had no effects on bone resorption and MNC formation in these in vitro systems. The inhibitory effect of menatetrenone on the calcium release from calvaria was not affected by the addition of 3 x 10(-5) M of warfarin, an inhibitor of vitamin K cycle. The same concentration of geranylgeraniol, the side-chain component of menatetrenone at the 3-position of the naphthoquinone, inhibited tartrate-resistant acid phosphatase (TRACP) activity and MNC formation to the same degree as menatetrenone. Phytol, the side-chain component of vitamin K1, did not affect TRACP activity at all doses tested, but weakly inhibited MNC formation. Moreover, multi-isoprenyl alcohols of two to seven units, except geranylgeraniol which contains four units, did not effect MNC formation. These findings suggest that the inhibitory effect of menatetrenone on bone resorption is not due to gamma-carboxylation and that the side chain of menatetrenone may play an important role in this inhibitory effect.

SecY protein, a membrane-embedded secretion factor of E. coli, is cleaved by the ompT protease in vitro

SecY is an integral membrane protein, spanning the cytoplasmic membrane of E. coli probably 10 times and required for efficient translocation of other proteins across the membrane. We report here that this protein can be specifically cleaved at the central region of the polypeptide after cell disruption, and cytoplasmic membrane preparations often contain a degradation product of SecY. This cleavage was ascribed to the action of the outer membrane-associated protease specified by the ompT gene, since the cleavage was not observed in ompT-defective mutants. Thus, we propose that an ompT mutant should be used for in vitro analysis of protein translocation and the SecY protein. We mutated the ompT gene by insertion of a kanamycin resistance determinant to facilitate strain construction by P1 transduction.

FtsH (HflB) is an ATP-dependent protease selectively acting on SecY and some other membrane proteins

The FtsH protein is a membrane-bound ATPase of Escherichia coli that was proposed to be involved in membrane protein assembly as well as degradation of some unstable proteins. SecY, a subunit of protein translocase, is FtsH dependently degraded in vivo when it fails to associate with its partner (the SecE protein). We constructed a series of mutants in which mutations were introduced into conserved residues in the two ATP binding consensus sequences or the zinc binding sequence of FtsH. We purified wild-type and mutant FtsH proteins by making use of a polyhistidine tag attached to their carboxyl termini. Complementation analysis and ATPase activity assays in vitro indicated that, of the two sets of ATP binding sequence motifs, the one located C-terminally (A1) is essential for ATPase activity and in vivo functioning of FtsH. Wild-type FtsH protein degraded purified SecY in an ATP hydrolysis-dependent manner in vitro. Mutant proteins without ATPase activity were inactive in proteolysis. A zinc binding motif mutant showed a decreased proteolytic activity. SecY and FtsH were cross-linkable with each other in the membrane, provided that FtsH had an ATPase-inactivating mutation. These results demonstrate that FtsH binds to and degrades SecY, its A1 motif and the zinc binding motif being important for the proteolytic activity. FtsH-dependent proteolysis was also demonstrated for SecY in crude membrane extracts, whereas a majority of other membrane proteins were not degraded, indicating that FtsH has high selectivity in protein degradation.

Cell growth and lambda phage development controlled by the same essential Escherichia coli gene, ftsH/hflB

The lambda phage choice between lysis and lysogeny is influenced by certain host functions in Escherichia coli. We found that the frequency of lambda lysogenization is markedly increased in the ftsH1 temperature-sensitive mutant. The ftsH gene, previously shown to code for an essential inner membrane protein with putative ATPase activity, is identical to hflB, a gene involved in the stability of the phage cII activator protein. The lysogenic decision controlled by FtsH/HflB is independent of that controlled by the protease HflA. Overproduction of FtsH/HflB suppresses the high frequency of lysogenization in an hflA null mutant. The FtsH/HflB protein, which stimulates cII degradation, may be a component of an HflA-independent proteolytic pathway, or it may act as a chaperone, maintaining cII in a conformation subject to proteolysis via such a pathway. Suppressor mutations of ftsH1 temperature-sensitive lethality, located in the fur gene (coding for the ferric uptake regulator), did not restore FtsH/HflB activity with respect to lambda lysogenization.

The SecY membrane component of the bacterial protein export machinery: analysis by new electrophoretic methods for integral membrane proteins

The product of the secY (prlA) gene (the SecY protein) involved in protein export in Escherichia coli was overproduced and localized in the cytoplasmic (inner) membrane. Because of its strong interaction with a non-ionic detergent (NP40), it partitioned into the detergent layer during electroblotting through a NP40-containing gel (detergent blotting), and it formed a horizontal streak in the O'Farrell two-dimensional gel electrophoretic system. Consequently, we developed an alternative two-dimensional gel procedure, which proved useful for analysis of integral membrane proteins, especially in combination with detergent blotting. SDS-gel electrophoresis was carried out successively through gels of lower (first dimension) and higher (second dimension) sieving effects. Many membrane proteins, unlike soluble proteins, formed spots off and above the diagonal line, and all of these spots partitioned exclusively into the detergent layer. A characteristic pattern of integral membrane proteins of E. coli was thus obtained and the spot of the SecY protein in the cytoplasmic membrane was identified even when it was not overproduced. These results show that the gene secY specifies an integral membrane component of the protein export machinery.

Hyaluronate receptors mediating glioma cell migration and proliferation

The extracellular matrix (ECM) of the central nervous system (CNS) is enriched in hyaluronate (HA). Ubiquitous receptors for HA are CD44 and the Receptor for HA-Mediated Motility known as RHAMM. In the present study, we have investigated the potential role of CD44 and RHAMM in the migration and proliferation of human astrocytoma cells. HA-receptor expression in brain tumor cell lines and surgical specimens was determined by immunocytochemistry and western blot analyses. The ability of RHAMM to bind ligand was determined through cetylpyridinium chloride (CPC) precipitations of brain tumor lysates in HA-binding assays. The effects of HA, CD44 blocking antibodies, and RHAMM soluble peptide on astrocytoma cell growth and migration was determined using MTT and migration assays. Our results show that the expression of the HA-receptors, CD44, and RHAMM, is virtually ubiquitous amongst glioma cell lines, and glioma tumor specimens. There was a gradient of expression amongst gliomas with high grade gliomas expressing more RHAMM and CD44 than did lower grade lesions or did normal human astrocytes or non-neoplastic specimens of human brain. Specific RHAMM variants of 85- and 58-kDa size were shown to bind avidly to HA following CPC precipitations. RHAMM soluble peptide inhibited glioma cell line proliferation in a dose-dependent fashion. Finally, while anti-CD44 antibodies did not inhibit the migration of human glioma cells, soluble peptides directed at the HA-binding domain of RHAMM inhibited glioma migration both on and off an HA-based ECM. These data support the notion that HA-receptors contribute to brain tumor adhesion, proliferation, and migration, biological features which must be better understood before more effective treatment strategies for these tumors can be found.

Synergism of BSF-2/interleukin 6 and interleukin 3 on development of multipotential hemopoietic progenitors in serum-free culture

We investigated the effects of B cell stimulatory factor 2/interleukin 6 (BSF-2/IL-6) on the development of murine hemopoietic progenitors using serum-containing culture and serum-free culture. In serum-containing culture, BSF-2 mainly supported multipotential blast cell colonies from spleen cells of normal and 5-fluorouracil (5-FU)-treated mice. In serum-free culture, no colony growth was seen in the presence of BSF-2. Addition of BSF-2 to the serum-free culture containing IL-3 resulted in a significant increase in the number of colonies formed from multipotential progenitors in spleen cells and bone marrow cells of 5-FU-treated mice, whereas no effects were seen on the number of single or oligolineage colonies formed by the spleen cells of normal mice. These results suggested that BSF-2 and IL-3 act synergistically on the multipotential progenitors but not on the maturer progenitors. When BSF-2 was added to a culture containing low concentrations of IL-3 (1 U/ml, 4 U/ml), which had little effect on colony formation, the number of total colonies formed by the spleen cells and bone marrow cells of 5-FU-treated mice increased significantly. The combination of BSF-2 and 40 U/ml of IL-3 resulted in a significant enlargement of GMM colonies. Thus, BSF-2 appears to enhance the sensitivity of multipotential hemopoietic progenitors to IL-3.