4-Phenyl-1,2,3,6-tetrahydropyridine, an excellent fragment to improve the potency of PARP-1 inhibitors

We have shown that a 4-phenyl-1,2,3,6-tetrahydropyridine fragment plays an important role in improving inhibitory potency against poly(ADP-ribose) polymerase-1 (PARP-1). Various benzamide analogues linked with this fragment via alkyl spacers have been prepared and evaluated. As a result, some of them have been found to be highly potent PARP-1 inhibitors.

Design, synthesis, and structure–activity relationships of potent GPIIb/IIIa antagonists: discovery of FK419

The discovery of the non-peptide antiplatelet injectable agent FK419 is reported. Based on the beta-turn structure of RGD peptide sequences in the alpha chain of fibrinogen, which binds the glycoprotein IIb/IIIa (GPIIb/IIIa) on the surface of platelets to induce platelet aggregation, the prototype 2 was designed. After further substituent effects were investigated at the alpha-position of the carboxylic acid in 2, we enhanced platelet aggregation inhibition, and discovered the useful feature of reduced prolongation of bleeding time. Finally, the potent platelet aggregation inhibitor FK419 (3) could be discovered. FK419 shows a safe feature of reduced prolongation of bleeding time, as well as potent inhibition of platelet aggregation.

Cytoplasmic chaperones in precursor targeting to mitochondria: the role of MSF and hsp 70

Despite extensive study since the early 1980s, the mechanism by which newly synthesized protein precursors are unfolded in the cytoplasm and targeted correctly to the mitochondrial surface prior to translocation through the mitochondrial membranes is understood poorly. Recently, an N-ethylmaleimide (NEM)-sensitive cytoplasmic factor called mitochondrial import stimulation factor (MSF), which catalyses the ATP-dependent unfolding of precursor proteins, was described. Unlike the more general chaperone proteins of the hsp70 families, MSF not only unfolds proteins but also targets the unfolded precursor proteins to the mitochondria. Here, Mihara and Omura summarize what is known about MSF and speculate on how it, and other cytoplasmic factors, may be involved in mitochondrial import.

FK419, a nonpeptide platelet glycoprotein IIb/IIIa antagonist, ameliorates brain infarction associated with thrombotic focal cerebral ischemia in monkeys: comparison with tissue plasminogen activator

The binding of platelet glycoprotein (GP) IIb/IIIa to fibrinogen is the final common pathway in platelet aggregation, a process known to play a key role in the pathogenesis of ischemic brain damage. We compared the effects of FK419, a novel nonpeptide GPIIb/IIIa antagonist, with recombinant tissue plasminogen activator (rt-PA) on middle cerebral artery (MCA) patency and ischemic brain damage in a thrombotic stroke model in squirrel monkeys. FK419 not only inhibited in vitro platelet aggregation (IC50: 88 nmol/L), but also showed disaggregatory activity to aggregated platelet (EC50: 286 nmol/L). FK419 dose-dependently reduced the time to first reperfusion and total occlusion time of MCA blood flow when administered immediately after the termination of photoirradiation. FK419 reduced cerebral infarction and ameliorated neurologic deficits with similar dose-dependency. Although rt-PA reduced the time to first reperfusion, total occlusion time, and cerebral infarction, it did not significantly ameliorate neurologic deficits and induced petechial intracerebral hemorrhages. These results indicate: (1) FK419 restored cerebral blood flow after thrombotic occlusion of MCA, (2) FK419 reduced ischemic brain injury by its thrombolytic actions in a non-human primate stroke model, and (3) FK419 has superior antithrombotic efficacy and is safer than rt-PA.

FK419, a novel nonpeptide GPIIb/IIIa antagonist, restores microvascular patency and improves outcome in the guinea-pig middle cerebral artery thrombotic occlusion model: comparison with tirofiban

The antithrombotic efficacy of FK419, a novel nonpeptide platelet glycoprotein IIb/IIIa antagonist, was compared with tirofiban in guinea-pigs. FK419 and tirofiban similarly inhibited platelet aggregation in vitro (IC50 values: 0.43+/-0.076 and 0.41+/-0.053 micromol/L) and dispersed aggregated platelets (EC50 values: 2.3+/-0.88 and 2.0+/-0.81 micromol/L). FK419 inhibited retention of platelets and neutrophils in a collagen-coated bead column with greater potency than tirofiban (IC50 values of 0.90+/-0.133 and 2.4+/-0.21 micromol/L for platelet retention and 0.32+/-0.078 and 0.57+/-0.180 micromol/L for neutrophil retention). When FK419 or tirofiban were administered after photochemically induced middle cerebral artery (MCA) occlusion in guinea-pigs, they dose-dependently improved MCA patency. FK419 reduced neurological deficits and ischemic brain damage in a dose-dependent fashion, whereas tirofiban did not. Reduced regional cerebral blood flow in the striatum gradually returned to the preoccluded level with FK419 treatment; however, no restoration was observed with tirofiban even though the MCA was recanalized. These results indicate that FK419 ameliorates ischemic brain damage by not only lysing the obstructive thrombus in MCA but also preventing or restoring microcirculation deficits after occlusion/reperfusion, suggesting that FK419 would be an attractive intervention for the treatment of ischemic stroke patients.

Restoration of middle cerebral artery thrombosis by novel glycoprotein IIb/IIIa antagonist FK419 in guinea pig

We compared the antithrombotic efficacy of FK419 [(S)-2-acetylamino-3-[(R)-[1-[3-(piperidin-4-yl)propionyl]piperidin-3-ylcarbonyl]amino] propionic acid trihydrate], a novel nonpeptide glycoprotein IIb/IIIa antagonist, with recombinant tissue plasminogen activator (rt-PA) and other antithrombotic agents (aspirin, ozagrel, argatroban and heparin). FK419 not only inhibited ADP- and collagen-induced guinea pig platelet aggregation, but also induced disaggregation for ADP-induced aggregated platelets in vitro. In the photochemically induced middle cerebral artery thrombosis model in guinea pigs, FK419 dose-dependently shortened the time to first reperfusion and the total middle cerebral artery occlusion time and reduced ischemic brain damage and ameliorated neurological deficits measured 24 h after middle cerebral artery occlusion. Rt-PA similarly improved the middle cerebral artery patency, brain damage and neurological deficits. Neither aspirin, ozagrel, argatroban nor heparin restored the middle cerebral artery blood flow and improved the brain damage or neurological deficits. These results demonstrated that novel glycoprotein IIb/IIIa antagonist FK419 could disperse thrombus and ameliorated ischemic brain damage, suggesting that FK419 would be an attractive intervention for stroke patients.

Rational approaches to discovery of orally active and brain-penetrable quinazolinone inhibitors of poly(ADP-ribose)polymerase

A novel class of quinazolinone derivatives as potent poly(ADP-ribose)polymerase-1 (PARP-1) inhibitors has been discovered. Key to success was application of a rational discovery strategy involving structure-based design, combinatorial chemistry, and classical SAR for improvement of potency and bioavailability. The new inhibitors were shown to bind to the nicotinamide-ribose binding site (NI site) and the adenosine-ribose binding site (AD site) of NAD+.

Vital role of the itch-scratch response in development of spontaneous dermatitis in NC/Nga mice

BACKGROUND

The itch sensation and the resultant response, scratching, are important symptoms of atopic dermatitis (AD) and have a significant impact on the quality of life of affected patients. However, the influence of the itch-scratch response on the pathology of AD has not been precisely elucidated.

OBJECTIVES

To investigate the role of scratching behaviour in the development of spontaneous dermatitis using conventionally raised NC/Nga mice (Conv-NC mice), which are known to be an animal model for human AD.

METHODS

Capsaicin-sensitive sensory nerves of the mice were ablated by neonatal capsaicin treatment (Cap-NC mice), and the development of spontaneous dermatitis in the Cap-NC mice was compared chronologically with that in Conv-NC mice.

RESULTS

Scratching behaviour was almost completely prevented in Cap-NC mice raised for 84 days under conventional conditions, and the development of dermatitis and elevation of the serum IgE level were significantly suppressed. Histological analysis revealed that the numbers of infiltrating eosinophils and mast cells in the lesional skin of Cap-NC mice were lower than those in Conv-NC mice. Immunological studies showed that the capability of spleen T cells to produce both T-helper (Th) 1 (interferon-gamma) and Th2 [interleukin (IL)-5 and IL-13] cytokines was diminished in Cap-NC mice. Furthermore, serum levels of IL-18 were approximately twice higher in Conv-NC mice than in Cap-NC mice.

CONCLUSIONS

These observations suggest that scratching behaviour contributes to the development of dermatitis by enhancing various immunological responses in the murine AD model, implying that prevention of the itch sensation and/or itch-associated scratching behaviour is an effective treatment for AD.

An application of a new planar positron imaging system (PPIS) in a small animal: MPTP-induced Parkinsonism in mouse

OBJECTIVE

Recent animal PET research has led to the development of PET scanners for small animals. A planar positron imaging system (PPIS) was newly developed to study physiological function in small animals and plants in recent years. To examine the usefulness of PPIS for functional study in small animals, we examined dopaminergic images of mouse striata in MPTP-induced parkinsonism.

METHODS

Male C57BL/6NCrj mice were treated with MPTP 7 days before the PPIS study. Scans were performed to measure dopamine D1 receptor binding and dopamine transporter availability with [11C]SCH23390 (about 2 MBq) and [11C]beta-CFT (about 2 MBq), respectively. After the PPIS study, dopamine content in the striatum was measured by HPLC.

RESULTS

The MPTP treatment significantly reduced dopamine content in the striatum 7 days after treatment. In the MPTP-treated group, [11C]beta-CFT binding in the striatum was significantly decreased compared with the control group, while striatal [11C]SCH23390 binding was not affected. Dopamine content in the striatum was significantly correlated with the striatal binding of [11C]beta-CFT.

CONCLUSION

The present results suggest that PPIS is able to determine brain function in a small animal. Using PPIS, high throughput imaging of small animal brain functions could be achieved.

Chimeric receptors with 4-1BB signaling capacity provoke potent cytotoxicity against acute lymphoblastic leukemia

To develop a therapy for drug-resistant B-lineage acute lymphoblastic leukemia (ALL), we transduced T lymphocytes with anti-CD19 chimeric receptors, consisting of an anti-CD19 single-chain variable domain (reactive with most ALL cases), the hinge and transmembrane domains of CD8alpha, and the signaling domain of CD3zeta. We compared the antileukemic activity mediated by a novel receptor ('anti-CD19-BB-zeta') containing the signaling domain of 4-1BB (CD137; a crucial molecule for T-cell antitumor activity) to that of a receptor lacking costimulatory molecules. Retroviral transduction produced efficient and durable receptor expression in human T cells. Lymphocytes expressing anti-CD19-BB-zeta receptors exerted powerful and specific cytotoxicity against ALL cells, which was superior to that of lymphocytes with receptors lacking 4-1BB. Anti-CD19-BB-zeta lymphocytes were remarkably effective in cocultures with bone marrow mesenchymal cells, and against leukemic cells from patients with drug-resistant ALL: as few as 1% anti-CD19-BB-zeta-transduced T cells eliminated most ALL cells within 5 days. These cells also expanded and produced interleukin-2 in response to ALL cells at much higher rates than those of lymphocytes expressing equivalent receptors lacking 4-1BB. We conclude that anti-CD19 chimeric receptors containing 4-1BB are a powerful new tool for T-cell therapy of B-lineage ALL and other CD19+ B-lymphoid malignancies.

A New Poly(ADP-Ribose) Polymerase Inhibitor, FR261529 [2-(4-Chlorophenyl)-5-quinoxalinecarboxamide], Ameliorates Methamphetamine-Induced Dopaminergic Neurotoxicity in Mice

Methamphetamine (METH) administration in mice, results in a chronic dopamine (DA) depletion associated with nerve terminal damage, with DA oxidation and generation of reactive oxygen species (ROS) primarily mediating this neurotoxicity. The oxidative stress induced by METH putatively activates nuclear enzyme poly(ADP-ribose) polymerase (PARP), with excessive PARP activation eventually leading to cell death. In this study, we show that prevention of PARP activation by treatment with FR261529 [2-(4-chlorophenyl)-5-quinoxalinecarboxamide], the compound that was recently identified as a novel PARP inhibitor (IC50 for PARP-1 = 33 nM, IC50 for PARP-2 = 7 nM), protects against both ROS-induced cells injury in vitro and METH-induced dopaminergic neuronal damage in an in vivo Parkinson's disease (PD) model. In PC12 cells, exposure of hydrogen peroxide or METH markedly induced PARP activation, and treatment with FR261529 (1 microM) significantly reduced PARP activation and attenuated cell death. In the mouse METH model, METH (15 mg/kg x 2 i.p., 2 h apart) intoxication accelerated DA metabolism and oxidation in the striatum, with subsequent cell damage in nigrostriatal dopaminergic neurons after 4 days. Oral administration of FR261529 (10 or 32 mg/kg) attenuated the damage of dopaminergic neurons via marked reduction of PARP activity and not via changes in dopamine metabolism or body temperature. These findings indicate that the neuroprotective effects of a novel PARP inhibitor, FR261529, were accompanied by inhibition of METH-induced PARP activation, suggesting that METH induces nigrostriatal dopaminergic neurodegeneration involving PARP activation and also orally active and brain-penetrable PARP inhibitor FR261529 could be a novel attractive therapeutic candidate for neurodegenerative disorders such as PD.

Neuroprotective Effects of a Novel Poly(ADP-Ribose) Polymerase-1 Inhibitor, 2-{3-[4-(4-Chlorophenyl)-1-piperazinyl] propyl}-4(3H)-quinazolinone (FR255595), in an in Vitro Model of Cell Death and in Mouse 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine Model of Parkinson's Disease

The massive activation of poly(ADP-ribose) polymerase-1 (PARP-1) by DNA-damaging stimuli, such as exposure to reactive oxygen species (ROS), can lead to cell injury via severe, irreversible depletion of the NAD and ATP pool, and PARP-1 inhibitors have been expected to rescue neurons from degeneration in a number of disease models. We have recently identified 2-[3-[4-(4-chlorophenyl)-1-piperazinyl] propyl]-4(3H)-quinazolinone (FR255595) as a novel and potent PARP-1 inhibitor through structure-based drug design and high-throughput screening. This compound potently inhibited PARP activity with an IC(50) value of 11 nM and was orally active and highly brain penetrable. Here, we show that prevention of PARP activation by FR255595 protects against both ROS-induced cells injury in vitro and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced nigrostriatal dopaminergic damage in an in vivo Parkinson's disease (PD) model. In cell death models in vitro, exposure of hydrogen peroxide induced cell death with PARP overactivation in PC12 cells and SH-SY5Y cells, and pre- and post-treatment with FR255595 (10(-9)-10(-5) M) significantly reduced PARP activation and cell death. In mouse MPTP model, MPTP (20 mg/kg i.p.) intoxication lead to PARP activation and cell damage in the nigrostriatal dopaminergic pathway, which was significantly ameliorated by oral administration of FR255595 (10-32 mg/kg), both in the substantia nigra and in the striatum via marked reduction of PARP activation, even with delayed treatment. These findings clearly indicate that the novel PARP-1 inhibitor FR255595 exerts neuroprotective effect through its potent PARP-1 inhibitory actions in PD model, suggesting that the drug could be an attractive candidate for several neurodegenerative disorders, including PD.

Antithrombotic Effects of FK419, a Novel Nonpeptide Platelet GPIIb/IIIa Antagonist, in a Guinea Pig Photochemically Induced Middle Cerebral Artery Thrombosis Model: Comparison with Ozagrel and Argatroban

Platelet activation and subsequent aggregation play a key role in the pathogenesis of ischemic brain damage. Recent studies revealed that enhanced platelet activation is also observed after ischemia, suggesting that secondary thrombus formation might participate in the development of cerebral infarction. The binding of platelet glycoprotein GPIIb/IIIa (integrin alpha(IIb)beta3) to fibrinogen is the final common pathway in platelet aggregation. Therefore, GPIIb/IIIa antagonists might be useful in acute ischemic stroke as well as in the secondary prevention of ischemic stroke. In the present study, we evaluated the effect of three compounds, FK419 ((S)-2-acetylamino-3-[(R)-[1-[3-(piperidin-4-yl) propionyl] piperidin-3-ylcarbonyl] amino] propionic acid trihydrate), a novel nonpeptide GPIIb/IIIa antagonist, ozagrel, a selective thromboxane A(2) synthase inhibitor, and argatroban, a thrombin inhibitor, on middle cerebral artery (MCA) patency and ischemic brain damage using photochemically induced MCA thrombosis model in guinea pigs. FK419, ozagrel, or argatroban was administered 5 min after the termination of photoirradiation. FK419 dose-dependently improved MCA patency by decreasing the total occlusion time, time to continuous reperfusion, and the number of cyclic flow reductions, at doses that inhibited ADP-induced platelet aggregation ex vivo. In contrast, ozagrel only improved total occlusion time, and argatroban showed no improvement in MCA patency. FK419 also reduced ischemic brain damage in a dose-dependent fashion, whereas ozagrel and argatroban did not. Finally, FK419 ameliorated neurological deficits, whereas ozagrel and argatroban did not. These results indicate that FK419, a GPIIb/IIIa antagonist, ameliorates ischemic brain damage by improving MCA patency after occlusion and that FK419 is a promising candidate for the treatment of acute ischemic stroke.

Inhibition of arterial thrombosis by a protease-activated receptor 1 antagonist, FR171113, in the guinea pig

The antiplatelet and antithrombotic effects of FR171113, 3-(4-chlorophenyl)-2-(2,4-dichlorobenzoylimino)-5-(methoxycarbonyl methylene)-1,3-thiazolidin-4-one, a non-peptide protease-activated receptor 1 (PAR1) antagonist, were evaluated in guinea pigs. FR171113 inhibited Ser-Phe-Leu-Leu-Arg-Asn-NH2 (a synthetic PAR1 agonist peptide)-induced and thrombin-induced aggregation of guinea pig platelets in a concentration-dependent manner in vitro (IC50=1.5 and 0.35 microM, respectively). Subcutaneous administration of FR171113 (0.1-3.2 mg/kg) produced a dose-dependent inhibition of platelet aggregation ex vivo. The ED50 value of FR171113 for platelet aggregation was 0.49 mg/kg s.c. However, FR171113 did not have an inhibitory effect on ADP- or collagen-induced platelet aggregation in vitro and ex vivo. One hour after FR171113 treatment at 1.0 mg/kg s.c., significant inhibition of arterial thrombosis without a prolongation of thrombin time or coagulation time was seen in the FeCl3-induced carotid artery thrombosis model in guinea pigs. Furthermore, FR171113 did not prolong bleeding time even at 32 mg/kg s.c., which is a much higher dose than that required in the thrombosis model. These observations indicate that FR171113 has desirable antiplatelet effects both in vitro and in vivo and that its in vivo antithrombotic activity is efficacious without causing a prolongation of bleeding time.

Signals mediated by FcgammaRIIA suppress the growth of B-lineage acute lymphoblastic leukemia cells

We examined Fc receptor expression and function in normal and leukemic human immature B cells. Fc receptor expression increased with normal B cell maturation: CD32(+) cells composed 8.1% +/- 1.2% (mean +/- s.d.) of the least mature (CD34(+)CD10(+)), 19.2% +/- 5.7% of intermediate (CD34(-)CD10(+)), and 82.4% +/- 5.0% of mature (CD34(-)CD10(-)) bone marrow CD19(+) B cells. Forty-five of 57 primary B-lineage acute lymphoblastic leukemia samples and all six cell lines studied expressed Fc receptors. By RT-PCR and antibody staining, FcgammaRIIA was the Fc receptor predominantly expressed in these cells. FcgammaRIIA ligation in RS4;11 and 380 cells induced tyrosine phosphorylation of CD32, CD19, CBL, SYK, P13-K p85 and SHIP, as well as RasGAP association with tyrosine-phosphorylated p62(dok). These signalling events resulted in a marked suppression of leukemia cell growth. After a 7-day exposure to anti-CD32, the recovery of ALL cells cocultured with stroma was reduced to 5.5% +/- 2.8% of control values in 380 cells (n = 14), 19.4% +/- 6.1% (n = 8) in RS4;11, and 4.0% +/- 1.3% (n = 6) in KOPN55bi. CD32 ligation also reduced cell recovery in five of seven CD32(+) primary leukemia samples. Thus, FcgammaRIIA mediates signals that suppress the growth of lymphoid leukemia cells.

Association between TaqI A dopamine D2 receptor polymorphism and therapeutic response to bromperidol: a preliminary report

The relationship between TaqI A dopamine D2 receptor (DRD2) polymorphism and therapeutic response to bromperidol, a selective dopamine antagonist, was investigated in 30 acutely exacerbated schizophrenic inpatients. Patients were treated with bromperidol 6-18 mg/day for 3 weeks. Clinical symptoms were evaluated by the Brief Psychiatric Rating Scale (BPRS) before and 3 weeks after the treatment. The TaqI A genotypes were determined with the PCR method. There was no significant difference in the percentage improvement of total BPRS or 5-subgrouped symptoms (positive, negative, anxiety-depression, excitement and cognitive symptoms) after the 3-week treatment between the patients with A1 alleles (n=18) and those with no A1 allele (n=12). Although the present study is preliminary, it is suggested that the TaqI A DRD2 polymorphism is not associated with therapeutic response to bromperidol in schizophrenic patients.

NHE6 protein possesses a signal peptide destined for endoplasmic reticulum membrane and localizes in secretory organelles of the cell

The NHE6 protein is a unique Na(+)/H(+) exchanger isoform believed to localize in mitochondria. It possesses a hydrophilic N-terminal portion that is rich in positively charged residues and many hydrophobic segments. In the present study, signal sequences in the NHE6 molecule were examined for organelle localization and membrane topogenesis. When the full-length protein was expressed in COS7 cells, it localized in the endoplasmic reticulum and on the cell surface. Furthermore, the protein was fully N-glycosylated. When green fluorescent protein was fused after the second (H2) or third (H3) hydrophobic segment, the fusion proteins were targeted to the endoplasmic reticulum (ER) membrane. The localization pattern was the same as that of fusion proteins in which green fluorescent protein was fused after H2 of NHE1. In an in vitro system, H1 behaved as a signal peptide that directs the translocation of the following polypeptide chain and is then processed off. The next hydrophobic segment (H2) halted translocation and eventually became a transmembrane segment. The N-terminal hydrophobic segment (H1) of NHE1 also behaved as a signal peptide. Cell fractionation studies using antibodies against the 15 C-terminal residues indicated that NHE6 protein localized in the microsomal membranes of rat liver cells. All of the NHE6 molecules in liver tissue possess an endoglycosidase H-resistant sugar chain. These findings indicate that NHE6 protein is targeted to the ER membrane via the N-terminal signal peptide and is sorted to organelle membranes derived from the ER membrane.

Relationship between Taq1 A dopamine D2 receptor (DRD2) polymorphism and prolactin response to bromperidol

The dopamine D2 receptor (DRD2) gene has a Taq1 A restriction fragment length polymorphism yielding two alleles, A1 and A2. We have previously shown that female patients with the A1 allele show greater prolactin response to nemonapride, a selective antagonist for D2-like dopamine receptors, in schizophrenic patients. In the present study, the relationship between this polymorphism and prolactin response to bromperidol was investigated in 32 untreated schizophrenic inpatients (16 males, 16 females). The daily dose of bromperidol was fixed at 6 (n = 10), 12 (n = 13), or 18 mg (n = 9) during a 2-week treatment period. Taq1 A genotypes were determined by PCR method. Plasma prolactin concentration was measured by radioimmunoassay. Plasma concentration of bromperidol was measured by HPLC method. The subjects were divided into four subgroups by gender and the genotypes, i.e., 10 males and 11 females with the A1 allele, 6 males and 5 females with no A1 allele. The females with the A1 allele had the highest Delta prolactin (the change from the pretreatment concentration)/bromperidol concentration ratio among the other groups (P < 0.05). The present study thus suggests that female patients with the A1 allele show greater prolactin response to bromperidol, who may have a high risk for adverse effects associated with neuroleptic-induced hyperprolactinemia.

Spectroscopic characterization of the photocycle intermediates of photoactive yellow protein

The absorption spectra of photocycle intermediates of photoactive yellow protein mutants were compared with those of the corresponding intermediates of wild type to probe which amino acid residues interact with the chromophore in the intermediate states. B and H intermediates were produced by irradiation and trapped at 80 K, and L intermediates at 193 K. The absorption spectra of these intermediates produced from R52Q were identical to those from wild type, whereas those from E46Q and T50V were 7-15 nm red-shifted as those in the dark states. The absorption spectra of M intermediates were measured by flash photolysis at room temperature. Those of Y42F, T50V, and R52Q were identical to that of wild type, whereas that of E46Q was 11 nm red-shifted. Assuming that the intermediates of mutants have a structure comparable to that of wild type, these findings suggest the following: Glu46 interacts with the chromophore throughout the photocycle, interaction between the chromophore and Thr50 as well as Tyr42 is lost upon the formation of M intermediate, and Arg52 never interacts with the chromophore directly. The hydrogen-bonding network around the phenolic oxygen of the chromophore would be thus maintained until L intermediate decays, and the global conformational change would take place by the loss of the hydrogen bond between the chromophore and Tyr42. This model conflicts with some of the results of previous crystallographic studies, suggesting that the reaction mechanism in the crystal may be different from that in solution.

Identification and characterization of two novel mutations (Q421 K and R123P) in congenital factor XII deficiency

The factor XII genes of two unrelated factor XII-deficient Japanese families were screened, and two novel mutations were identified. A heterozygous mutation (Q421K) was identified in the gene of a cross-reacting material (CRM)-negative patient with reduced FXII activity (entitled Case 1). No mutations were discovered in the other allele. Case 2 was a CRM-negative patient with severe FXII deficiency. In this case, a homozygous mutation (R123P) was discerned. Expression studies in Chinese Hamster Ovary (CHO) cells demonstrated accumulation of mutant Q421 K factor XII in the cell, and insufficient secretion, while the R123P mutant showed lower levels of accumulation than wild-type, and no evidence of secretion in culture supernatant. In the presence of proteasome inhibitor, all types of FXII (wild-type. Q421K, R123P) accumulated in the cells. Protease protection experiments using the microsomal fraction of these cell lines demonstrated that while 20% wild-type FXII (total wild-type:100%) and 10% R123P mutant (total R123P-type: 40%) were resistant to treatment with trypsin, 50% Q421K-type FXII (total Q421K-type:130%) remained resistant to digestion. From these results, we conclude that Q421K is less susceptible to proteasome degradation than wild-type, but is unable to exit the ER efficiently, resulting in insufficient secretion phenotype. In contrast, R123P is susceptible to proteasome degradation and is not secreted.

Direct targeting of cis-Golgi matrix proteins to the Golgi apparatus

The targeting route of newly synthesized GM130 and GRASP65 to the Golgi apparatus was investigated by three different approaches. First, localization of pulse labeled GM130 and GRASP65 in normal rat kidney (NRK) cells was traced by subcellular fractionation followed by immunoprecipitation. Immediately after the pulse labeling, GM130 and GRASP65 were found in the Golgi but not in the endoplasmic reticulum (ER) membrane fractions, whereas a control Golgi membrane protein was still found in the ER membrane fractions. Second, epitope tagged GM130 and GRASP65 were expressed in NRK cells by plasmid microinjection into the nuclei and their localization was analyzed by immunofluorescence. When ER to Golgi transport was inhibited by prior microinjection of a GTP-restricted mutant of Sar1 protein into the cytosol, the expressed GM130 and GRASP65 showed clear Golgi localization. Last, binding of GM130 and GRASP65 to the membranes was analyzed in vitro. In vitro synthesized GM130 and GRASP65 specifically bound to purified Golgi membranes but not to microsomal membranes. The bound GM130 and GRASP65 were found to form a complex with pre-existing counterparts on the Golgi membrane. These results strongly suggested that GM130 and GRASP65 are directly targeted to the Golgi membrane without initial assembly on the ER and subsequent vesicular transport to the Golgi apparatus.

Amino acid residues before the hydrophobic region which are critical for membrane translocation of the N-terminal domain of synaptotagmin II

We examined the fine structure of the type I signal-anchor sequence of synaptotagmin II, which has a 60-residue N-terminal domain followed by a hydrophobic region (H-region), focusing on the hinge region between the N-terminal and the H-regions. It was found that the charged or highly polar residues support the translocation of the N-terminal domain through the endoplasmic reticulum membrane at specific positions in the hinge. The residue requirement correlated with the turn propensity scale for transmembranes. It is suggested that a certain conformation, likely helical hairpin, in the hinge is critical for N-terminal domain translocation.

[Neoadjuvant chemotherapy for advanced epithelial ovarian cancer]

Primary surgical cytoreduction followed by paclitaxel/carboplatin combination chemotherapy currently is the treatment of choice for advanced epithelial ovarian cancer. Aggressive surgery is widely accepted as a valid approach to initial cytoreduction of stage III disease, but suboptimal residual disease following primary surgical resection is one of the most important adverse prognostic factors in these patients. Neoadjuvant chemotherapy has been proposed as an alternative approach to conventional surgery for initial management of bulky ovarian cancer, with the goal of improving surgical quality. General acceptance of neoadjuvant chemotherapy as an alternative to primary surgery for patients who are not ideal surgical candidates remains limited, because equivalent or superior survival has not yet been demonstrated in a prospective randomized study. A large-scale, prospective, randomized study is being conducted by the European Organization for Research and Treatment of Cancer (EORTC) Gynecologic Cancer Cooperative Group and Gynecologic Oncology Group (GOG) to compare outcomes (overall and progression-free survival, quality of life, treatment complications) of neoadjuvant chemotherapy/interval debulking surgery versus primary cytoreductive surgery/adjuvant chemotherapy in patients with advanced epithelial ovarian carcinoma.