Domain analysis of the actin-binding and actin-remodeling activities of drebrin

Drebrin is an actin-binding protein which is expressed at highly levels in neurons. When introduced into fibroblasts, it has been known to bind to F-actin and to cause remodeling of F-actin. Here, we performed a domain analysis of the actin-binding and actin-remodeling activities of drebrin. Various fragments of drebrin cDNA were fused with green fluorescent protein cDNA and introduced into Chinese hamster ovary cells. Association of the fusion protein with F-actin and remodeling of the F-actin were examined. We found that the central 85-amino-acid sequence (residues 233-317) was sufficient for the binding to and remodeling of F-actin. The binding activity of this fragment was relatively low compared with that of full-length drebrin, but all the types of abnormalities of F-actin that are observed with full-length drebrin were also observed with this fragment. When this sequence was further fragmented, the actin-binding activity was greatly reduced and the actin-remodeling activity disappeared. The actin-binding activity of the central region of drebrin was confirmed by a cosedimentation assay of chymotryptic fragments of drebrin with purified actin. These data indicate that the actin-binding domain and actin-remodeling domain are identical and that this domain is located at the central region of drebrin.

An allele of the ripening-specific 1-aminocyclopropane-1-carboxylic acid synthase gene (ACS1) in apple fruit with a long storage life

An allele of the 1-aminocyclopropane-1-carboxylic acid (ACC) synthase gene (Md-ACS1), the transcript and translated product of which have been identified in ripening apples (Malus domestica), was isolated from a genomic library of the apple cultivar, Golden Delicious. The predicted coding region of this allele (ACS1-2) showed that seven nucleotide substitutions in the corresponding region of ACS1-1 resulted in just one amino acid transition. A 162-bp sequence characterized as a short interspersed repetitive element retrotransposon was inserted in the 5'-flanking region of ACS1-2 corresponding to position -781 in ACS1-1. The XhoI site located near the 3' end of the predicted coding region of ACS1-2 was absent from the reverse transcriptase-polymerase chain reaction product, revealing that exclusive transcription from ACS1-1 occurs during ripening of cv Golden Delicious fruit. DNA gel-blot and polymerase chain reaction analyses of genomic DNAs showed clearly that apple cultivars were either heterozygous for ACS1-1 and ACS1-2 or homozygous for each type. RNA gel-blot analysis of the ACS1-2 homozygous Fuji apple, which produces little ethylene and has a long storage life, demonstrated that the level of transcription from ACS1-2 during the ripening stage was very low.

Enhanced expression and differential inducibility of soybean chalcone synthase genes by supplemental UV-B in dark-grown seedlings

By developing gene-specific RT-PCR and using filters to allow transmission down to 290 nm (UV-B+) or blocking all radiation below 320 nm (UV-B(-)), the effect of UV-B+ and UV-B- light on expression of each of the presently known seven members of soybean chalcone synthase (CHS) gene family in dark-grown seedlings was analyzed. Dark expression was detectable already in 18 h dark-germinating embryos, with progressive increases on successive days, suggesting that chs belongs to a class of genes expressed very early during germination, and that the expression at this stage is either constitutive or induced by non-light-dependent factors present in the seed or made available following imbibition. Exposure of 18 h dark-germinating embryos to UV-B- or to UV-B+ light did not lead to an increase in chs signal. However, the 24 h dark-germinating embryos showed a distinct effect of UV-B+, interestingly coinciding with the stage when the head of seedlings was in the process of being pushed up above ground by stem elongation, suggesting the possibility of a developmental switch modulating the appearance of UV-B response. The response to UV-B- was most prominent in chs1 and almost silent in chs2, while the up-regulation by UV-B+ was most prominent in chs5 and chs6 and much less so in chs2. Interestingly, chs2 was noted to be the only member of the Gmchs gene family devoid of H-box, raising the possibility that the H-box may be a good indicator of the photo-inducibility of a chs gene.

Regulation of actin binding and actin bundling activities of fascin by caldesmon coupled with tropomyosin

Human fascin is an actin-bundling protein and is thought to play a role in the formation of microfilament bundles of microspikes and stress fibers in cultured cells. To explore the regulation of fascin-actin interaction, we have examined the effects of culture cell caldesmon and tropomyosin (TM) on actin binding activity of human fascin. Caldesmon alone or TM alone has little or no effect on the actin binding of fascin. However, caldesmon together with TM completely inhibits actin binding of human fascin. When calmodulin is added, the inhibition of fascin-actin interaction by caldesmon and TM becomes Ca2+ dependent because Ca2+/calmodulin blocks actin binding of caldesmon. Furthermore, as phosphorylation of caldesmon by cdc2 kinase inhibits actin binding of caldesmon, phosphorylation can also control actin binding of fascin in the presence of TM. As expected by the inhibition of fascin-actin binding, caldesmon coupled with TM also inhibits actin bundling activity of fascin. Whereas smooth muscle caldesmon alone or TM alone shows no effect, caldesmon together with TM completely inhibits actin bundling activity of fascin. This inhibition is again Ca2+ dependent when calmodulin is added to the system. These results suggest important roles for caldesmon and TM in the regulation of the function of human fascin.

The surgical treatment of lung lacerations and major bronchial disruptions caused by blunt thoracic trauma

The records of 16 patients who suffered blunt thoracic trauma, causing lung lacerations in 13, bronchial disruptions in 2, and lung laceration with bronchial disruption in 1, were reviewed to investigate the correlations between clinical factors and prognosis. The causes of these injuries included 14 traffic accidents and 2 construction-related accidents, and the indications for surgery were massive bleeding in 12 patients, massive air leakage in 2, both in 1, and lung abscess in 1. Of the 16 patients, 11 (68.8%) underwent thoracotomy less than 4 h after admission, 3 (18.8%) underwent thoracotomy 4 to 24 h after admission, and 2 (12.5%) underwent thoracotomy 24 h or later after admission. The operative techniques included 1 pneumonectomy, 5 lobectomies, 2 bronchoplasties, and 8 minor repairs. The mortality rate was 43.7%, which included six early deaths occurring within 72 h of the trauma, and one late death. While major bronchial disruption is usually associated with a good prognosis, univariate and multivariate analyses demonstrated that intrapleural bleeding of 300 ml/h or more from time of trauma to chest tube drainage was significantly correlated with a poor prognosis. Moreover, an injury severity score (ISS) of 36 or more showed a trend toward a correlation with poor prognosis in patients with lung lacerations. Prompt thoracotomy will decrease mortality rate of patients suffering lung lacerations resulting in intrapleural bleeding of more than 300 ml/h.

Aortic root replacement for Takayasu arteritis associated with ulcerative colitis and ankylosing spondylitis--report of a case

A 26-year-old man was admitted for treatment of congestive heart failure resulting from aortic regurgitation. The patient had been on medical treatment for ulcerative colitis (UC) since he was 14 years old and for ankylosing spondylitis (AS) since he was 20 years old. On admission, gradients of blood pressure among the extremities were observed. Echocardiography revealed marked dilation of the left ventricle (LV), hypokinetic wall motion of the LV, slightly prolapsed aortic cusps with annular dilatation, and severe aortic regurgitation. Computed tomographic scans demonstrated an aneurysmal dilation of the ascending aorta and thickening of the descending and abdominal aortic wall. Digital subtraction angiography demonstrated an aneurysmal dilation of the ascending aorta; however, there was no clear evidence of steno-occlusive lesions in the brachiocephalic vessels. Blood studies showed positive inflammatory signs and negative rheumatoid factor. HLA typing showed A2, 24(9), B27, 67, Cw1, 7, and DR1, 2. Based on these data, the diagnosis of Takayasu arteritis associated with UC and AS was made. Aortic root replacement was performed. Steroid therapy was restarted immediately after surgery. Histologic studies of the aortic wall showed findings compatible with Takayasu arteritis. The combination of these rare diseases suggests that they have a common pathophysiologic background.

In vitro long-term culture of human primitive hematopoietic cells supported by murine stromal cell line MS-5

When Lin-CD34+CD38- cells from normal human cord blood were cocultured with MS-5, colony forming cells were maintained for over 8 weeks. Prevention of contact between MS-5 and Lin-CD34+CD38- cells by using a membrane filter was negligible for this activity, indicating that the activity of MS-5 on human primitive hematopoietic cells may be due to soluble factor(s) secreted from MS-5. We tried to purify this activity by a [3H]TdR incorporation assay. The activity was found in 150 kD fraction and was neutralized with anti-mSCF (stem cell factor) antibody. Another 20-30 kD fraction synergized with mSCF to stimulate the growth of Lin-CD34+CD38- cells but failed alone. This fraction supported the growth of the G-CSF (granulocyte-colony stimulating factor)-dependent cell line FD/GR3, FDC-P2 transfected with mG-CSF receptor cDNA. This synergy was canceled in the presence of soluble mG-CSF receptor. Addition of anti-mSCF antibody and soluble mG-CSF receptor to the culture completely abrogated the activity of MS-5-culture supernatant. These results indicate the activity of MS-5 on Lin-CD34+CD38- cells is due to synergistic effect of mSCF and mG-CSF.

Parallel evolution in radiation of Ohomopterus ground beetles inferred from mitochondrial ND5 gene sequences

Molecular phylogenetic analyses using mitochondrial NADH dehydrogenase subunit 5 (ND5) gene sequences representing all 15 species and the majority of subspecies or races of the Ohomopterus ground beetles from all over the Japanese archipelago have uncovered a remarkable evolutionary history. Clustering of the species in the molecular phylogenetic tree is linked to their geographic distribution and does not correlate with morphological characters. Taxonomically the "same" species or the members belonging to the same species-group fall out in more than two different places on the ND5 tree. Evidence has been presented against a possible participation of ancestral polymorphism and random lineage sorting or of hybrid individuals for the observed distribution of mitochondrial DNA haplotypes. The most plausible explanation of our results is that parallel evolution took place in different lineages. Most notably, O. dehaanii, O. yaconinus, and O. japonicus in a lineage reveal almost identical morphology with those of the "same" species (or subspecies) but belonging to the phylogenetically remote lineages.

Modulatory role of drebrin on the cytoskeleton within dendritic spines in the rat cerebral cortex

Morphological changes in the dendritic spines have been postulated to participate in the expression of synaptic plasticity. The cytoskeleton is likely to play a key role in regulating spine structure. Here we examine the molecular mechanisms responsible for the changes in spine morphology, focusing on drebrin, an actin-binding protein that is known to change the properties of actin filaments. We found that adult-type drebrin is localized in the dendritic spines of rat forebrain neurons, where it binds to the cytoskeleton. To identify the cytoskeletal proteins that associated with drebrin, we isolated drebrin-containing cytoskeletons using immunoprecipitation with a drebrin antibody. Drebrin, actin, myosin, and gelsolin were co-precipitated. We next examined the effect of drebrin on actomyosin interaction. In vitro, drebrin reduced the sliding velocity of actin filaments on immobilized myosin and inhibited the actin-activated ATPase activity of myosin. These results suggest that drebrin may modulate the actomyosin interaction within spines and may play a role in the structure-based plasticity of synapses.

NK cell trafficking and cytokine expression in splenic compartments after IFN induction and viral infection

Studies were undertaken to characterize mechanisms for NK cell cytokine delivery in vivo. Conditions of systemic IFN-beta expression elicited by polyinosinic-polycytidylic acid (poly(I:C)) treatment or IFN-alpha beta production during lymphocytic choriomeningitis virus or murine cytomegalovirus infections resulted in profound splenic histologic changes, with relocalization of nucleated cells from red to white pulp regions. Cell-trafficking experiments, with fluorescently labeled populations, showed that poly(I:C) induced T/B cell-dependent leukocyte migration into white pulp regions. Splenic leukocytes prepared from severe combined immunodeficient (SCID) and bone marrow cells prepared from SCID or normal C57BL/6 mice revealed a unique poly(I:C)-induced accumulation of non-T/non-B cells along splenic red and white pulp region borders characteristic of marginal zones. Lymphocytic choriomeningitis virus and murine cytomegalovirus infections also induced this trafficking pattern. Ab treatments of normal and SCID cell donor mice to eliminate specific cell subsets demonstrated that the unique migration of non-T/non-B cells was dependent upon cells with the NK phenotype, NK1.1+ AGM1+F4/80-. In situ hybridization showed that, at early times after infections, small proportions of cells along red and white pulp divisions expressed high levels of IFN-gamma mRNA, and that these cells were depleted by protocols eliminating NK cells. The results suggest an exciting model for induction of NK cell trafficking from bone marrow to secondary compartments. This migratory pattern may localize NK cells to receive additional activation signals and/or to precisely deliver NK cell-produced cytokines.

NK cell trafficking and cytokine expression in splenic compartments after IFN induction and viral infection

Studies were undertaken to characterize mechanisms for NK cell cytokine delivery in vivo. Conditions of systemic IFN-beta expression elicited by polyinosinic-polycytidylic acid (poly(I:C)) treatment or IFN-alpha beta production during lymphocytic choriomeningitis virus or murine cytomegalovirus infections resulted in profound splenic histologic changes, with relocalization of nucleated cells from red to white pulp regions. Cell-trafficking experiments, with fluorescently labeled populations, showed that poly(I:C) induced T/B cell-dependent leukocyte migration into white pulp regions. Splenic leukocytes prepared from severe combined immunodeficient (SCID) and bone marrow cells prepared from SCID or normal C57BL/6 mice revealed a unique poly(I:C)-induced accumulation of non-T/non-B cells along splenic red and white pulp region borders characteristic of marginal zones. Lymphocytic choriomeningitis virus and murine cytomegalovirus infections also induced this trafficking pattern. Ab treatments of normal and SCID cell donor mice to eliminate specific cell subsets demonstrated that the unique migration of non-T/non-B cells was dependent upon cells with the NK phenotype, NK1.1+ AGM1+F4/80-. In situ hybridization showed that, at early times after infections, small proportions of cells along red and white pulp divisions expressed high levels of IFN-gamma mRNA, and that these cells were depleted by protocols eliminating NK cells. The results suggest an exciting model for induction of NK cell trafficking from bone marrow to secondary compartments. This migratory pattern may localize NK cells to receive additional activation signals and/or to precisely deliver NK cell-produced cytokines.

Granulocyte-colony stimulating factor and stem cell factor are the crucial factors in long-term culture of human primitive hematopoietic cells supported by a murine stromal cell line

The findings that murine marrow stromal cell line MS-5 supported the proliferation of human lineage-negative (Lin-) CD34+CD38- bone marrow cells in long-term culture have been reported. In this study, we analyzed this proliferating activity of MS-5-conditioned medium (CM) on human primitive hematopoietic cells. When Lin-CD34+CD38- cells of normal human cord blood cells were co-cultured with MS-5, colony forming cells (CFCs) were maintained over 7 weeks in vitro. Prevention of contact between MS-5 and Lin-CD34+CD38- cells by using membrane filter (0.45 micron) was negligible for this activity. This indicated that the activity of MS-5 on human primitive hematopoietic cells is a soluble factor(s) secreted from MS-5, which is not induced by the contact between MS-5 and Lin-CD34+CD38- cells. We tried to purify this soluble activity. An active material with a molecular weight of about 150 kDa, determined by gel filtration chromatography, solely supported the growth of Lin-CD34+CD38- cells and Mo7e, a human megakaryocytic cell line. This activity not only reacted with anti-mouse stem cell factor (mSCF) antibody on Western blots, but it was also neutralized in the presence of anti-mSCF antibody. Another active material with a molecular weight of about 20-30 kDa synergized with mSCF to stimulate the growth of Lin-CD34+CD38- cells but failed to do so alone, although this synergy was inhibited in the presence of soluble mouse granulocyte-colony stimulating factor (mG-CSF) receptor, which is a chimeric protein consisting of the extracellular domain of mG-CSF receptor and the Fe region of human IgG1. In addition, the latter molecule supported the growth of the G-CSF dependent cell line FD/GR3, which is a murine myeloid leukemia cell line, FDC-P2, transfected with mG-CSF receptor cDNA. Adding of anti-mSCF antibody and soluble mG-CSF receptor to the culture completely abrogated the activity of MS-5-CM. Recombinant (r) mSCF and rmG-CSF had synergistic activity on the growth of Lin-CD34+CD38- cells. These results indicated that the activity on Lin-CD34+CD38- cells included in MS-5-CM is based upon the synergistic effects of mSCF and mG-CSF.

[Factors related to ADL of stroke patients three months after discharge]

Focusing on the ADL of stroke patients, 94 hemiplegia cases in rehabilitation units of acute care general hospitals were studied to identify factors affecting ADL, measured using the Barthel Index, 3 months after discharge. The main results were as follows: 1. The 8 independent variables: age, gender, length of hospitalization, degree of paralysis of lower extremities at discharge, motivation toward rehabilitation, sight, Barthel scores at discharge, and the expression of one's intentions emerged as the 8 reliable predictive factors (R = .904, R2 = .817). 2. It may be deduced that in older patients in particular, a status of amyotrophy has a significant influence on ADL after discharge. The 94 stroke patients were divided into two age groups-44 patients aged 64 years or younger, and 50 patients aged 65 years or older. Barthel scores at 3 months after discharge were analyzed by multiple regression analysis in both groups. The result was that ADL, after discharge, of the aged 65 years or older group, was more affected by their status at discharge, than was it with the 64 years or younger group (64 years or younger; R = .871, R2 = .758, 65 years or older; R = .934, R2 = .873). 3. For patients in the 64 years or younger group, Barthel scores at 3 months after discharge were significantly related to age, length of hospitalization, sight, Barthel scores at discharge and expression of one's intentions. For patients in the 65 years or older group, the results were significantly related to sight, Barthel scores at discharge, and motivation for rehabilitation.

Inhibition by drebrin of the actin-bundling activity of brain fascin, a protein localized in filopodia of growth cones

The purification of drebrin, an actin-binding protein that is specifically expressed in embryonic rat brain, was described previously. During the purification of drebrin, we found that an actin-binding protein of 54 kDa was also expressed at high levels in embryonic brain, and this protein was identified by immunoblotting as fascin. To explore the roles of fascin in brain development, we purified fascin from brains of infant rats and characterized it. We found that the actin-binding activity of fascin was strongly inhibited by drebrin. Fascin caused formation of actin bundles, a process that was inhibited in the presence of drebrin, as confirmed by electron microscopy and a low-speed centrifugation assay. In PC12 cells, fascin was localized in the filopodia of growth cones, whereas drebrin was localized in the basal region of growth cones. Our results suggest that fascin might play an important role in the organization of actin in filopodia and that this organization might be regulated by drebrin.

Phylogenetic relationships and evolution of the Japanese Carabinae ground beetles based on mitochondrial ND5 gene sequences

The phylogenetic relationships of the Japanese Carabinae ground beetles were analyzed by comparing 1,069 nucleotide sequences in the mitochondrial gene encoding NADH dehydrogenase subunit 5 (ND5). The ND5 phylogenetic tree revealed that the hind-wingless Carabina and the hind-winged Calosoma/Campalita (Calosomina) diverged from the common ancestor, and Cychrus (Cychrini) is the outgroup of them. Five distinct clusters (groups) can be recognized in the Carabina, i.e., CARABUS, HEMICARABUS, LEPTOCARABUS, APOTOMOPTERUS, and PROCRUSTES/DAMASTER. The ancestors of these lineages diverged almost at the same time more than 10 Myr ago. The Carabus cluster includes two subclusters, Carabus and Ohomopterus. Two species of Carabus examined are phylogenetically rather remote, while five species among Ohomopterus are closely related to each other. The results suggest that diversification of Carabus started much earlier than that of Ohomopterus, presumably in the Eurasian continent, and that of Ohomopterus in the Japanese archipelago. The branching order in the LEPTOCARABUS lineage was established, Authenocarabus/Pentacarabus being their outgroup. In the DAMASTER/PROCRUSTES lineage, Procrustes is placed as the outgroup of Damaster, with the branching order of Coptolabrus and Acoptolabrus/Damaster. The diversification of the Damaster subspecies appeared to have occurred in the Japanese archipelago earlier than Ohomopterus, and its phylogeny reflects their geographic distribution in the archipelago rather than the morphological characters.

The fastest actin-based motor protein from the green algae, Chara, and its distinct mode of interaction with actin

The endoplasmic streaming in Characean cells is an actin-dependent movement. The motor protein responsible for the streaming was partially purified and characterized. It was soluble at low ionic strength, an ATPase of a molecular mass of 225 kDa and activated more than 100 times by muscle F-actin. Surprisingly, in an in vitro motility assay, the motor protein moved muscle F-actin at 60 microns/s, which is similar to the velocity of streaming in a living cell and 10 times faster than muscle myosin. Proteolytic cleavage of actin impaired movement crucially on muscle myosin, but did not affect movement at all on the Chara motor protein, suggesting that the Chara motor protein would interact with actin via a set of sites different from those of muscle myosin.

Hematopoietic stem cells found in lineage-positive subsets in the bone marrow of 5-fluorouracil-treated mice

It is known that treatment of mice with 5-fluorouracil (5-FU, 150 mg/kg) confers radioprotection. To investigate this effect, we performed bone marrow transplantation (BMT) using C57BL/6-Ly5 congenic mice treated with 5-FU five days prior to experiments. The mononuclear cells (MNC) in 5-FU-treated bone marrow (BM) were 10 times more radioprotective than those in untreated BM. Moreover, the number of BM MNC expressing c-kit on their surface from 5-FU-treated mice was markedly decreased relative to those from untreated controls. These results showed that the surface characteristics of cells that contributed to this radio-protective effect differ from those of stem cells as reported recently. BM MNC of mice treated with 5-FU were separated on the basis of expression of the lineage-specific antigens (Lin), c-kit, and Ly6A/E. When injected into lethally irradiated mice, 1,000 Lin+ and Lin-c-kit+Ly6A/E+ cells showed radioprotective effects such that 100% and 60% survived, respectively. Flow cytometric analysis 165 days after BMT showed that 88.8% and 65.1% of peripheral blood (PB) in mice transplanted with Lin+ and Lin-c-kit+Ly6A/E+ was derived from donor mice, respectively. After six months, donor-derived Lin-c-kit+Ly6A/E+ cells which showed radioprotective effects on a secondary irradiated host were detected from mice transplanted with Lin+ cells from 5-FU-treated mice. Taken together, these findings demonstrated that stem cells expressing Lin+ present in the BM of mice treated with 5-FU other than Lin-c-kit+Ly6A/E+ cells and these Lin+ cells play an important role in the recovery of myeloablative mice.

Purification of an ATP-dependent actin-binding protein from a lower eukaryote, Physarum polycephalum

A novel protein with a molecular mass of 55 kDa, as determined by SDS-PAGE, was purified from plasmodia of Physarum polycephalum. The protein bound to actin filaments with a stoichiometry of 0.27 moles per mole of actin with an apparent dissociation constant of 4 x 10(-8) M. In the presence of ATP, the protein dissociated from actin filaments. Adenosine 5-(gamma-thio)triphosphate and adenyl-5'-yl imidodiphosphate also abolished the actin-binding activity of the protein, but GTP did not. Because the cytoplasmic concentration of ATP oscillates in association with the shuttle streaming of the cytoplasm, it is possible that this protein might be involved in the actin-linked regulation of cytoplasmic streaming.

Drebrin, a development-associated brain protein from rat embryo, causes the dissociation of tropomyosin from actin filaments

Drebrin is a development-associated neuroprotein whose cDNA into fibroblasts causes the formation of dendrite-like structures (Shirao, T., Kojima, N., and Obata, K. (1992) Neuroreport 3, 109-112). To explore molecular functions of drebrin during brain development, we purified drebrin from brains of rat embryos. Drebrin bound to actin filaments at a stoichiometry of 1:5 with a dissociation constant (Kd) of 1.2 x 10(-7) M. It strongly inhibited the actin binding activity of tropomyosin. Excess amounts of tropomyosin also inhibited the drebrin binding to actin filaments, suggesting that drebrin and tropomyosin competitively bind to actin filaments. Further, drebrin inhibited not only the actin binding activity of alpha-actinin but also the actin cross-linking activity of alpha-actinin. Gene transfection experiments revealed that tropomyosin was dissociated from actin filaments in drebrin-overexpressing fibroblasts. Thus we hypothesize that drebrin may destabilize actin filaments by dissociating tropomyosin and alpha-actinin from actin filaments, resulting in the formation of axon and dendrites during neuronal development.