Partial amino acid sequence and mRNA analysis of cytosolic pyridoxine-beta-D-glucoside hydrolase from porcine intestinal mucosa: proposed derivation from the lactase-phlorizin hydrolase gene

We have previously identified and purified a novel beta-glucosidase, designated PNGH (pyridoxine-5'-beta-D-glucoside hydrolase), from the cytosolic fraction of pig intestinal mucosal. PNGH catalyses the hydrolysis of PNG (pyridoxine-5'-beta-D-glucoside), a plant derivative of vitamin B6 that exhibits partial nutritional bioavailability in humans and animals. Preliminary amino acid sequence analysis indicated regions of close similarity of PNGH to the precursor form of LPH (lactase-phlorizin hydrolase), the beta-glucosidase localized to the brush-border membrane. We report in the present study amino acid sequence data for PNGH and results of Northern blot analyses, upon which we propose a common genomic origin of PNGH and LPH. Internal Edman sequencing of the PNGH band isolated by SDS/PAGE yielded data for 16 peptides, averaging 10.8 amino acids in length. These peptides from PNGH (approx. 140 kDa) were highly similar to sequences existing over most of the length of the >200 kDa precursor of rabbit LPH; however, we found no PNGH sequences that corresponded to approx. 350 amino acids between positions 463 and 812 of the LPH precursor, a region encoded by exon 7 of the LPH precursor gene (amino acids 568-784), and no sequences that corresponded to regions near the N-terminus. MS analysis of tryptic peptides yielded 25 peptides, averaging 15 amino acids, with masses that matched segments of the rabbit LPH precursor. Northern blot analysis of pig and human small intestinal polyadenylated mRNA using a non-specific LPH cDNA probe showed an expected approx. 6 kb transcript of the LPH precursor, but also an approx. 4 kb transcript that was consistent with the size predicted from the PNGH protein mass. Using a probe specific to the region encoded by exon 7, hybridization occurred only with the 6 kb transcript. Based on these observations, we propose that both PNGH and LPH enzymes have the same genomic origin, but differ in transcriptional and, possibly, post-translational processing.

[The transobturator tape (TOT). A minimally-invasive procedure for the treatment of female urinary stress incontinence]

The transobturator tape, a new technique for the treatment of female urinary stress incontinence, was evaluated with a 1 year follow-up.A total of 124 patients were treated with a low elasticity polypropylene tape according to the technique described by Delorme. The operative procedure is described step by step. All patients were followed-up after 3, 6 and 12 months. No intra-operative complications were observed. After 12 months 88.7% of the patients were cured and an additional 6.4% showed improvement. The transobturator technique (from exterior to interior) is, given proven indications and an exact consideration of the instructions, a simple, safe and efficient surgical procedure for the treatment of female urinary stress incontinence. The technique avoids complications such as bladder, intestinal and vascular lesions. It is suitable for genuine incontinence and patients with recurrent stress incontinence.

Peptides eluted from HLA-B27 of human splenocytes and blood cells reveal a similar but partially different profile compared to in vitro grown cell lines

The sequences and profiles of peptides which bind to HLA-B*2705 splenocytes and peripheral blood cells were compared with those previously published from in vitro long-term cell cultures. B*2705 peptide profile analysed by solid-phase Edman degradation and 15 individual peptide sequences determined by LC-MS/MS were partially similar to those defined from in vitro long-term cell cultures. Arg at P2 was found in 11 of 15 sequenced peptides (73.3%). This value is lower in comparison with other published data. Two sequences were matching to unknown proteins, which displayed similarity with myosin. These are first data on peptide sequences isolated directly from HLA-B27 molecules without prior in vitro propagation of the cells.

Heparin-binding epidermal growth factor-like growth factor: a component in chromaffin granules which promotes the survival of nigrostriatal dopaminergic neurones in vitro and in vivo

Chromaffin cells can restore function to the damaged nigrostriatal dopaminergic system in animal models of Parkinson's disease. It has been reported that a protein which is released from chromaffin granules can promote the survival of dopaminergic neurones in vitro and protect them against N-methylpyridinium ion toxicity. This neurotrophic effect has been found to be mediated by astroglial cells and blocked by inhibitors of the epidermal growth factor (EGF) receptor signal transduction pathway. Here we report the identification of bovine heparin-binding EGF-like growth factor (HB-EGF) in chromaffin granules and the cloning of the respective cDNA from bovine-derived adrenal gland. Protein extracts from bovine chromaffin granules were found to promote the survival of embryonic dopaminergic neurones in culture, to the same extent as recombinant human HB-EGF. Furthermore, the neurotrophic action of the chromaffin granule extract could be abolished by antiserum to recombinant human HB-EGF. We also show that intracerebral injection of recombinant human HB-EGF protected the nigrostriatal dopaminergic system in an in vivo adult rat model of Parkinson's disease. Intracerebral administration of this protein at the same time as a 6-hydroxydopamine lesion of the medial forebrain bundle was found to spare dopamine levels in the striatum and tyrosine hydroxylase-immunopositive neurones in the midbrain. This study has found that the main component in chromaffin granules responsible for their neurotrophic effect on dopaminergic neurones is HB-EGF. Furthermore, HB-EGF has significant protective effects on nigrostriatal dopaminergic neurones in vivo, making it a potential candidate for use in the treatment of Parkinson's disease.

Phosphorylation influences the translation state of FMRP-associated polyribosomes

Fragile X mental retardation protein, FMRP, is absent in patients with fragile X syndrome, a common form of mental retardation. FMRP is a nucleocytoplasmic RNA binding protein that is primarily associated with polyribosomes. FMRP is believed to be a translational repressor and may regulate the translation of certain mRNAs at the base of dendritic spines in neurons. However, little is known about the regulation of FMRP. Using mass spectrometry and site-directed mutagenesis, we show that FMRP is phosphorylated between residues 483 and 521, N-terminal to the RGG box, both in murine brain and in cultured cells. Primary phosphorylation occurs on the highly conserved serine 499, which triggers hierarchical phosphorylation of nearby serines. FMRP is phosphorylated within 2-4 h of synthesis, however, phosphorylation has no effect on the half-life of the protein. In contrast to the Drosophila ortholog dFxr, the phosphorylation status of mammalian FMRP does not influence its association with specific mRNAs in vivo. However, we find unphosphorylated FMRP associated with actively translating polyribosomes while a fraction of phosphorylated FMRP is associated with apparently stalled polyribosomes. Our data suggest that the phosphorylation may regulate FMRP and that the release of FMRP-induced translational suppression may involve a dephosphorylation signal.

Cytosolic Arl2 is complexed with cofactor D and protein phosphatase 2A

Arl2 is a member of the ADP-ribosylation factor family of 20-kDa GTPases that is highly conserved in eukaryotes. Recent results revealed that a portion of cellular Arl2 and its binding partner, BART, localize to mitochondria. Because approximately 90% of cellular Arl2 is cytosolic, we investigated properties of the soluble protein and found that it is stably bound in a complex that migrates in gel filtration medium with a predicted molecular mass of approximately 300 kDa. This complex was purified approximately 500-fold from the soluble fraction of bovine brain. Protein components were identified by mass spectroscopy and revealed the presence of four other proteins that include the tubulin folding cochaperone cofactor D and all three subunits of at least two protein phosphatase 2A (PP2A) protein phosphatase trimers. The presence of more than one PP2A B-type subunit and the low stoichiometry of Arl2 indicate that the purified preparation still contains a mixture of complexes that cannot currently be completely resolved. Thus, although all the soluble Arl2 in bovine brain is in high molecular mass complexes, only a portion of the total cellular cofactor D and PP2A are associated with the Arl2. We further show that the Arl2 in the complex cannot bind GTP and that complexed cofactor D does not efficiently participate in tubulin refolding reactions in a manner comparable with free cofactor D. Our data suggest functional roles for the cytosolic Arl2 complex in modulating tubulin and microtubule behavior as well as a possible role in apoptosis.

Redox potential of human thioredoxin 1 and identification of a second dithiol/disulfide motif

Thioredoxin (Trx1) is a redox-active protein containing two active site cysteines (Cys-32 and Cys-35) that cycle between the dithiol and disulfide forms as Trx1 reduces target proteins. Examination of the redox characteristics of this active site dithiol/disulfide couple is complicated by the presence of three additional non-active site cysteines. Using the redox Western blot technique and matrix assisted laser desorption ionization time-of-flight mass spectrometry mass spectrometry, we determined the midpoint potential (E0) of the Trx1 active site (-230 mV) and identified a second redox-active dithiol/disulfide (Cys-62 and Cys-69) in an alpha helix proximal to the active site, which formed under oxidizing conditions. This non-active site disulfide was not a substrate for reduction by thioredoxin reductase and delayed the reduction of the active site disulfide by thioredoxin reductase. Within actively growing THP1 cells, most of the active site of Trx1 was in the dithiol form, whereas the non-active site was totally in the dithiol form. The addition of increasing concentrations of diamide to these cells resulted in oxidation of the active site at fairly low concentrations and oxidation of the non-active site at higher concentrations. Taken together these results suggest that the Cys-62-Cys-69 disulfide could provide a means to transiently inhibit Trx1 activity under conditions of redox signaling or oxidative stress, allowing more time for the sensing and transmission of oxidative signals.

Analysis of HLA-E peptide-binding specificity and contact residues in bound peptide required for recognition by CD94/NKG2

The MHC class Ib molecule HLA-E is the primary ligand for CD94/NKG2A-inhibitory receptors expressed on NK cells, and there is also evidence for TCR-mediated recognition of this molecule. HLA-E preferentially assembles with a homologous set of peptides derived from the leader sequence of class Ia molecules, but its capacity to bind and present other peptides remains to be fully explored. The peptide-binding motif of HLA-E was investigated by folding HLA-E in vitro in the presence of peptide libraries derived from a nonameric leader peptide sequence randomized at individual anchor positions. A high degree of selectivity was observed at four of five total anchor positions, with preference for amino acids present in HLA-E-binding peptides from class Ia leader sequences. Selectivity was also observed at the nonanchor P5 position, with preference for positively charged amino acids, suggesting that electrostatic interactions involving the P5 side chain may facilitate assembly of HLA-E peptide complexes. The observed HLA-E peptide-binding motif was strikingly similar to that previously identified for the murine class Ib molecule, Qa-1. Experiments with HLA-E tetramers bearing peptides substituted at nonanchor positions demonstrated that P5 and P8 are primary contact residues for interaction with CD94/NKG2 receptors. A conservative replacement of Arg for Lys at P5 completely abrogated binding to CD94/NKG2. Despite conservation of peptide-binding specificity in HLA-E and Qa-1, cross-species tetramer-staining experiments demonstrated that the interaction surfaces on CD94/NKG2 and the class Ib ligands have diverged between primates and rodents.

Structural comparison of human monoamine oxidases A and B: mass spectrometry monitoring of cysteine reactivities

Monoamine oxidases (MAO) A and B are approximately 60-kDa outer mitochondrial membrane flavoenzymes catalyzing the degradation of neurotransmitters and xenobiotic arylalkyl amines. Despite 70% identity of their amino acid sequences, both enzymes exhibit strikingly different properties when exposed to thiol-modifying reagents. Human MAO A and MAO B each contain 9 cysteine residues (7 in conserved sequence locations). MAO A is inactivated by N-ethylmaleimide (NEM) much faster (tau(1/2) = approximately 3 min) than MAO B (tau(1/2) = approximately 8 h). These differences in thiol reactivities are also demonstrated by monitoring the NEM modification stoichiometries by electrospray mass spectrometry. Inactivation of either enzyme with acetylenic inhibitors results in alterations of their thiol reactivities. Cys5 and Cys266 were identified as the only residues modified by biotin-derivatized NEM in clorgyline-inactivated MAO A and pargyline-inactivated MAO B, respectively. The x-ray structure of MAO B (Binda, C., Newton-Vinson, P., Hubalek, F., Edmondson, D. E., and Mattevi, A. (2002) Nat. Struct. Biol. 9, 22-26) shows that Cys5 is located on the surface of the molecule opposite to the membrane-binding region. Cys266 in MAO A is predicted to be located in the same region of the molecule. These thiol residues are also modified by biotin-derivatized NEM in the mitochondrial membrane-bound MAO A and MAO B. This study shows that the MAO A structure is "more flexible" than that of MAO B and that clorgyline and pargyline inactivation of MAO A and B, respectively, increases the structural stability of both enzymes. No evidence is found for the presence of disulfide bonds in either enzyme, contrary to a previous suggestion.

Specific in vitro cleavage of Mason-Pfizer monkey virus capsid protein: evidence for a potential role of retroviral protease in early stages of infection

Processing of Gag polyproteins by viral protease (PR) leads to reorganization of immature retroviral particles and formation of a ribonucleoprotein core. In some retroviruses, such as HIV and RSV, cleavage of a spacer peptide separating capsid and nucleocapsid proteins is essential for the core formation. We show here that no similar spacer peptide is present in the capsid-nucleocapsid (CA-NC) region of Mason-Pfizer monkey virus (M-PMV) and that the CA protein is cleaved in vitro by the PR within the major homology region (MHR) and the NC protein in several sites at the N-terminus. The CA cleavage product was also identified shortly after penetration of M-PMV into COS cells, suggesting that the protease-catalyzed cleavage is involved in core disintegration.

The Booroola mutation in sheep is associated with an alteration of the bone morphogenetic protein receptor-IB functionality

The hyperprolificacy phenotype of Booroola ewes is due to the presence of the FecB(B) allele at the FecB locus, recently identified as a single amino acid substitution (Q249R) in the bone morphogenetic protein (BMP) type-IB receptor (BMPR1B), and is associated with a more precocious differentiation of ovarian granulosa cells (GCs). To evaluate the consequences of the Booroola mutation on BMPR1B functions, the action of ligands of the transforming growth factor-beta (TGFbeta)/BMP family that act through (growth and differentiation factor-5, BMP-4) or independently of (activin A, TGFbeta-1) BMPR1B were studied on primary cultures of GCs from homozygous FecB(+) and FecB(B) ewes. All the tested TGFbeta/BMP family ligands inhibited progesterone secretion by FecB(+) GCs. Those inhibitory effects were lower for GCs from preovulatory (5-7 mm diameter) than from small antral follicles (1-3 mm diameter). The presence of the Booroola mutation was associated with a 3- to 4-fold (P<0.001) decreased responsiveness of GCs from FecB(B) compared with FecB(+) small follicles to the action of BMPR1B ligands. In contrast, TGFbeta-1 and activin A had similar inhibitory effects on progesterone secretion by GCs from FecB(+) and FecB(B) small follicles. No difference between genotypes was observed with GCs from preovulatory follicles. In transfection experiments with HEK-293 cells, co-expression of FecB(+) BMPR1B and BMPR2 resulted in a 2.6-fold (P<0.01) induction of the activity of a BMP-specific luciferase reporter construct by BMP-4. Interestingly, no response to BMP-4 was observed when cells were transfected with the FecB(B) form of the BMPR1B receptor. Overall, these data strongly suggest that the Q249R mutation is associated with a specific alteration of BMPR1B signaling in hyperprolific Booroola ewes.

The increased bactericidal activity of a fatty acid-modified synthetic antimicrobial peptide of human cathepsin G correlates with its enhanced capacity to interact with model membranes

The bactericidal potency of a synthetic peptide (CG 117-136) of human lysosomal cathepsin G (cat G) can be substantially increased by covalent attachment to its N- or C-termini, of saturated, linear fatty acids (FAs), namely those with C-8, C-10 and C-12 hydrocarbon chains. In order to understand better the mechanism by which FA moieties increase the bactericidal activity of CG 117-136, the interaction of N-terminally FA-modified peptides with artificial membranes was studied. First, the content of secondary structure motifs in the modified and unmodified peptides was determined by circular dichroism (CD). A marked increase in the propensity of FA-modified CG 117-136 to form an alpha-helix structure was observed for the C-8, C-10 and C-12 derivatives compared with unmodified/short-chain and long-chain (C-14, C-16, C-18) derivatives. These effects were observed both in the presence of large unilamellar liposomes or in trifuluoroethanol, a membrane-stimulating agent. Second, the capacity of peptides to insert into large unilamellar liposomes as a function of FA length was determined by their ability to release a trapped fluorescent dye. FA derivatives with the highest alpha-helical content were found to be the most effective in releasing a fluorescent dye, compared with an unmodified peptide and/or derivatives having a low alpha-helical content. The ability of the peptides to attain alpha-helical structure in the membrane-like environment and the ability to disrupt the liposomal membrane, therefore correlate remarkably well with their increased ability to kill bacteria. A plausible explanation for improved bactericidal action of the modified peptide is that the FA moiety facilitates formation of the peptide with an alpha-helical structure formation in membranes, which is essential for disrupting the integrity of the bacterial cytoplasmic membrane.

Cationic polypeptides are required for antibacterial activity of human airway fluid

In a search for direct evidence leading to the biological relevance of airway secretions in innate host defense, we characterized the antibacterial function of cationic polypeptides within minimally manipulated nasal fluid. In this study, we show that cationic antimicrobial polypeptides are responsible for most of the bactericidal activity of whole nasal fluid. The removal of cationic polypeptides using a cation-exchange resin ablated the activity of nasal fluid against Escherichia coli, Listeria monocytogenes, and Pseudomonas aeruginosa. By using a novel proteomic approach, we identified a dozen cationic peptides and proteins within nasal fluid, all of which either are known antimicrobial polypeptides or have other proposed roles in host defense. Of the three most abundant cationic polypeptides in nasal fluid, lysozyme was more effective than either lactoferrin or secretory leukoprotease inhibitor in restoring the antibacterial activity of the cationic polypeptide-depleted fluid against a mucoid cystic fibrosis isolate of P. aeruginosa.

Peptide-independent folding and CD8 alpha alpha binding by the nonclassical class I molecule, thymic leukemia antigen

The nonclassical class I molecule, thymic leukemia (TL), has been shown to be expressed on intestinal epithelial cells and to interact with CD8(+) intraepithelial T lymphocytes. We generated recombinant soluble TL (T18(d)) H chains in bacteria as inclusion bodies and refolded them with beta(2)-microglobulin in the presence or absence of a random peptide library. Using a mAb, HD168, that recognizes a conformational epitope on native TL molecules, we observed that protein folds efficiently in the absence of peptide. Circular dichroism analysis demonstrated that TL molecules have structural features similar to classical class I molecules. Moreover, thermal denaturation experiments indicated that the melting temperature for peptide-free TL is similar to values reported previously for conventional class I-peptide complexes. Our results also show that CD8alphaalpha binding is not dependent on either TL-associated peptide or TL glycosylation.

Tailoring an antibacterial peptide of human lysosomal cathepsin G to enhance its broad-spectrum action against antibiotic-resistant bacterial pathogens

Neutrophils contain several cationic antimicrobial proteins or peptides (CAPs) that exert antibiotic-like action against bacteria. These host-derived antibiotics kill susceptible bacteria by oxygen-independent mechanisms. Considerable interest in their activity has been generated in recent years due not only to their likely important role in innate host defense against infection, but also their possible use as therapeutic agents in treating infections caused by antibiotic-resistant pathogens. We have studied the antibacterial properties of human lysosomal cathepsin G (cat G). This highly cationic serine protease contains at least three antibacterial regions that by themselves can exert antibacterial action against Gram-negative bacteria, such as Pseudomonas aeruginosa. Only one of these peptides, defined by residues 117-136 of full-length cat G, has bactericidal action against Gram-positive pathogens, such as Staphylococcus aureus. Due to the broad-spectrum antibacterial action of this peptide, we have sought to define the amino acids within its primary sequence required for this activity and have developed variants with improved activity. This review emphasizes the importance of both cationicity and hydrophobicity as necessary characteristics for the antibacterial action of CAPs. It also proposes the strategy that naturally occurring large human CAPs can be dissected to smaller CAPs and then modified to enhance their activity in vitro. This approach could prove beneficial to those interested in developing antimicrobial peptides as therapeutic agents.

Neuropeptide F and its expression in the yellow fever mosquito, Aedes aegypti

A neuropeptide F (NPF) was isolated from an extract of adult Aedes aegypti mosquitoes based on its immunoreactivity in a radioimmunoassay for Drosophila NPF. After sequencing the peptide, cDNAs encoding the NPF were identified from head and midgut. These cDNAs encode a prepropeptide containing a 36 amino acid peptide with an amidated carboxyl terminus, and its sequence shows it to be a member of the neuropeptide F/Y superfamily. Immunocytochemistry and Northern blots confirmed that both the brain and midgut of females are likely sources of NPF, found at its highest hemolymph titer before and 24 h after a blood meal.

Synthesis and characterization of a collagen model delta-O-phosphohydroxylysine-containing peptide

The existence of delta-O-phosphohydroxylysine (HylP) residues in collagen has been reported. However, such phosphorylated residues have not been isolated nor has their location within the protein sequence been identified. To develop the analytical chemistry necessary for the identification of HylP in proteins, a model HylP-containing peptide, Phe-dl-HylP-Gly-Gln-Pro-Ala-Ile-Gly-Phe (I), was synthesized. The peptide was assembled using 9-fluorenylmethyloxycarbonyl (Fmoc)-based solid-phase synthesis; N(alpha)-Fmoc-dl-hydroxy-dl-Lys(N(epsilon)-tert-butyloxycarbonyl)-OH was used to incorporate Hyl, and global phosphitylation/oxidation was used to introduce the phosphate group. The pK(a2) of the phosphate group, as determined using 31P NMR, was 5.6. Phosphoamino acid analysis of I was performed using either dabsyl chloride or phenylisothiocyanate derivatization followed by microbore reversed-phase HPLC separation of N(alpha, epsilon)-didabsyl-HylP or N(alpha, epsilon)-diphenylthiocarbamyl-HylP. HylP was found to be relatively resistant to acid hydrolysis, allowing for its quantitation. Solid-phase Edman degradation of I was used for positive identification of N(alpha)-phenylthiohydantoin-N(epsilon)-phenylthiocarbamyl-HylP. The masses of the phenylthiohydantoin and dabsyl derivatives of HylP were confirmed by electrospray ionization triple-quadrupole (ESI-MS). Peptide I was positively identified as a phosphopeptide by ESI-MS/precursor-ion scanning. Low-energy ESI-MS/MS confirmed the position of HylP within the sequence of I. Phosphorylation of Hyl led to complete resistance of I to lysine-specific endopeptidases.

Interaction between metabotropic glutamate receptor 7 and alpha tubulin

Metabotropic glutamate receptors (mGluRs) mediate a variety of responses to glutamate in the central nervous system. A primary role for group-III mGluRs is to inhibit neurotransmitter release from presynaptic terminals, but the molecular mechanisms that regulate presynaptic trafficking and activity of group-III mGluRs are not well understood. Here, we describe the interaction of mGluR7, a group-III mGluR and presynaptic autoreceptor, with the cytoskeletal protein, alpha tubulin. The mGluR7 carboxy terminal (CT) region was expressed as a GST fusion protein and incubated with rat brain extract to purify potential mGluR7-interacting proteins. These studies yielded a single prominent mGluR7 CT-associated protein of 55 kDa, which subsequent microsequencing analysis revealed to be alpha tubulin. Coimmunoprecipitation assays confirmed that full-length mGluR7 and alpha tubulin interact in rat brain as well as in BHK cells stably expressing mGluR7a, a splice variant of mGluR7. In addition, protein overlay experiments showed that the CT domain of mGluR7a binds specifically to purified tubulin and calmodulin, but not to bovine serum albumin. Further pull-down studies revealed that another splice variant mGluR7b also interacts with alpha tubulin, indicating that the binding region is not localized to the splice-variant regions of either mGluR7a (900-915) or mGluR7b (900-923). Indeed, deletion mutagenesis experiments revealed that the alpha tubulin-binding site is located within amino acids 873-892 of the mGluR7 CT domain, a region known to be important for regulation of mGluR7 trafficking. Interestingly, activation of mGluR7a in cells results in an immediate and significant decrease in alpha tubulin binding. These data suggest that the mGluR7/alpha tubulin interaction may provide a mechanism to control access of the CT domain to regulatory molecules, or alternatively, that this interaction may lead to morphological changes in the presynaptic membrane in response to receptor activation.

Systemic chemotherapy with epirubicin for treatment of advanced or multifocal hepatocellular carcinoma

BACKGROUND

The purpose of this retrospective study was to determine the response rate and effect on survival of chemotherapy with epirubicin in non-resectable advanced hepatocellular carcinoma (HCC).

METHODS

Fifty-two patients with non-resectable disease were treated with epirubicin. A treatment cycle consisted of 20 mg/m(2) i.v. on days 1, 8 and 15 and was repeated every 4 weeks to a maximum dose of 1,000 mg/m(2). Forty-four patients were eligible for analysis.

RESULTS

Out of 44 patients, 1 (2.3%) achieved a complete response, 3 (6.8%) had partial responses and 16 (36%) had stable disease (SD). For patients with successful disease control (complete and partial responders and patients with SD), the median survival was 16.2 months; for non-responders, it was 6.1 months (p < 0.003). Eight (88.9%) of 9 patients with alpha-fetoprotein (AFP) levels <50 microg/l achieved successful disease control compared to 12 (34.9%) out of 35 patients with initially elevated AFP (p < 0.0001).

CONCLUSION

Epirubicin appears to be an active therapeutic option for patients with non-resectable HCC. Especially the subgroup of patients with low levels of AFP may benefit from this treatment.

Dicynthaurin: an antimicrobial peptide from hemocytes of the solitary tunicate, Halocynthia aurantium

We isolated a novel antimicrobial peptide, dicynthaurin, from hemocytes of a tunicate, Halocynthia aurantium. The native peptide had a mass of approximately 6.2 kDa and was composed of two 30-residue monomers without sequence homology to any previously identified peptides (ILQKAVLDCLKAAGSSLSKAAITAIYNKIT). Most cynthaurin molecules were C-terminally amidated and were linked covalently by a single cystine disulfide bond. When performed in membrane-mimetic environments, circular dichroism studies of dicynthaurin revealed largely alpha-helical conformations. Dicynthaurin's broad-spectrum activity encompassed Gram-positive (Micrococcus luteus, Staphylococcus aureus, Listeria monocytogenes) and Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa), but not Candida albicans, a fungus. Although dicynthaurin was purified from a marine invertebrate, its antimicrobial activity was optimal at NaCl concentrations below 100 mM. This suggests that the antimicrobial actions of this molecule may take place intracellularly (e.g., within a phagosome) rather than extracellularly.

Cyclic AMP-dependent protein kinase phosphorylates group III metabotropic glutamate receptors and inhibits their function as presynaptic receptors

Recent evidence suggests that the functions of presynaptic metabotropic glutamate receptors (mGluRs) are tightly regulated by protein kinases. We previously reported that cAMP-dependent protein kinase (PKA) directly phosphorylates mGluR2 at a single serine residue (Ser843) on the C-terminal tail region of the receptor, and that phosphorylation of this site inhibits coupling of mGluR2 to GTP-binding proteins. This may be the mechanism by which the adenylyl cyclase activator forskolin inhibits presynaptic mGluR2 function at the medial perforant path-dentate gyrus synapse. We now report that PKA also directly phosphorylates several group III mGluRs (mGluR4a, mGluR7a, and mGluR8a), as well as mGluR3 at single conserved serine residues on their C-terminal tails. Furthermore, activation of PKA by forskolin inhibits group III mGluR-mediated responses at glutamatergic synapses in the hippocampus. Interestingly, beta-adrenergic receptor activation was found to mimic the inhibitory effect of forskolin on both group II and III mGluRs. These data suggest that a common PKA-dependent mechanism may be involved in regulating the function of multiple presynaptic group II and group III mGluRs. Such regulation is not limited to the pharmacological activation of adenylyl cyclase but can also be elicited by the stimulation of endogenous G(s)-coupled receptors, such as beta-adrenergic receptors.

Photoaffinity labeling of human IRBP with all-trans-retinoic acid

Interphotoreceptor retinoid-binding protein (IRBP), found only in photosensitive tissues, is a large approximately 135-kDa glycoprotein that contains a fourfold repeat structure. IRBP may function as a buffer and prevent retinoid toxicity and retinoid degeneration. Here we asked (i) whether each repeat of IRBP possesses the capability of photo-crosslinking all-trans-retinoic acid (RA), (ii) within Repeat 1 whether a single retinoic acid-binding domain exists, and (iii) whether protease and CNBr digestion of Repeat 1 bound RA indicate the exact location of the binding site. 3H-RA cross-linked to all four repeats, consistent with the current model of multiple binding sites in IRBP. Acetone precipitation was effective in removing unbound 3H-RA. LysC and tryptic digestion of the RA-Repeat 1 detected 18- and 5-kDa bands, respectively. CNBr digestion showed two bands about 9 and 11 kDa in size. Our data suggests a single binding site near positions 151-160 in the center of Repeat 1.

Inductive activity of recombinant human growth and differentiation factor-5

Growth and differentiation factor-5 (GDF-5) is a divergent member of the transforming growth factor-beta/bone morphogenetic protein (BMP) superfamily that is required for proper skeletal patterning and development in the vertebrate limb. Based on the homology of GDF-5 with other bone-inducing BMP family members, the inductive activity of a recombinant form of human GDF-5 (rhGDF-5) was evaluated in a series of in vitro assays and in vivo bone-formation models. The in vitro response to rhGDF-5 resulted in the formation of chondrogenic nodules in fetal rat calvarial cells cultured in the context of collagen or collagen/hyaluronate extracellular matrices. Matrices loaded with rhGDF-5 induced ectopic cartilaginous and osseous tissue when implanted in subcutaneous or intramuscular sites. In non-human primate long-bone-defect and spinal-fusion models, rhGDF-5 combined with a mineralized collagen matrix induced bone formation in a manner equivalent to autogenous bone. These results highlight the unique potential of rhGDF-5 in a wide variety of orthopaedic applications.

The C-terminal tail of UNC-60B (actin depolymerizing factor/cofilin) is critical for maintaining its stable association with F-actin and is implicated in the second actin-binding site

Actin depolymerizing factor (ADF)/cofilin changes the twist of actin filaments by binding two longitudinally associated actin subunits. In the absence of an atomic model of the ADF/cofilin-F-actin complex, we have identified residues in ADF/cofilin that are essential for filament binding. Here, we have characterized the C-terminal tail of UNC-60B (a nematode ADF/cofilin isoform) as a novel determinant for its association with F-actin. Removal of the C-terminal isoleucine (Ile152) by carboxypeptidase A or truncation by mutagenesis eliminated F-actin binding activity but strongly enhanced actin depolymerizing activity. Replacement of Ile152 by Ala had a similar but less marked effect; F-actin binding was weakened and depolymerizing activity slightly enhanced. Truncation of both Arg151 and Ile152 or replacement of Arg151 with Ala also abolished F-actin binding and enhanced depolymerizing activity. Loss of F-actin binding in these mutants was accompanied by loss or greatly decreased severing activity. All of the variants of UNC-60B interacted with G-actin in an indistinguishable manner from wild type. Cryoelectron microscopy showed that UNC-60B changed the twist of F-actin to a similar extent to vertebrate ADF/cofilins. Helical reconstruction and structural modeling of UNC-60B-F-actin complex reveal how the C terminus of UNC-60B might be involved in one of the two actin-binding sites.