A truncated isoform of the PP2A B56gamma regulatory subunit reduces irradiation-induced Mdm2 phosphorylation and could contribute to metastatic melanoma cell radioresistance

F10, a subline of the B16 mouse melanoma cell line, is itself the parent of the more metastatic BL6 line. BL6 cells differ from F10 cells by an alteration of the gene encoding the B56gamma regulatory subunit of protein phosphatase 2A (PP2A), which results in mRNA encoding a truncated variant of the subunit (deltagamma1). Expression of deltagamma 1 protein is detectable only when BL6 cells are transplanted into mice and then gamma-irradiated. Recently, B56gamma subunit-containing PP2A holoenzymes have shown to dephosphorylate Mdm2, a negative regulator of p53. Thus, we assessed whether the expression of deltagamma1 affects irradiation-induced phosphorylation of Mdm2 and radioresistance of melanoma cells by perturbing the regulation of p53. Western blot analyses revealed that irradiated COS-7 and NIH3T3 cells stably expressing deltagamma1 showed significantly less irradiation-induced Mdm2 phosphorylation. Mdm2 phosphorylation reduces the ability of Mdm2 to target p53 for degradation, which probably explained why p53 protein levels in NIH3T3 cells expressing deltagamma1 were not significantly elevated by irradiation, unlike in wild-type cells. This was also true for F10 cells transfected with deltagamma1 (F10deltagamma1) when the cells expressed deltagamma1 after being irradiated in vivo. p53 mRNA levels in irradiated wild-type and deltagamma 1-expressing cells were both only slightly elevated, suggesting that Mdm2 regulates p53 levels by a post-transcriptional mechanism. p53-mediated induction of the pro-apoptotic gene encoding Bax was also significantly lower in F10deltagamma1 cells irradiated in vivo. Moreover, F10deltagamma1 and BL6 cells were less apoptotic than F10 cells when the cells were irradiated in vivo. The p53 in F10 cells appears to be as functional as that in NIH3T3 cells because irradiation-induced expression of p53-target genes was comparable in both cells. Collectively, deltagamma1 appears to reduce irradiation-induced Mdm2 phosphorylation, which then blocks irradiation-stimulated p53 accumulation. Defects, such as deltagamma1, in PP2A may thus contribute to melanoma cell radioresistance.

Postischemic administration of Sendai virus vector carrying neurotrophic factor genes prevents delayed neuronal death in gerbils

Sendai virus (SeV) vector-mediated gene delivery of glial cell line-derived neurotrophic factor (GDNF) and nerve growth factor (NGF) prevented the delayed neuronal death induced by transient global ischemia in gerbils, even when the vector was administered several hours after ischemia. Intraventricular administration of SeV vector directed high-level expression of the vector-encoded neurotrophic factor genes, which are potent candidates for the treatment of neurodegenerative diseases. After occlusion of the bilateral carotid arteries of gerbils, SeV vector carrying GDNF (SeV/GDNF), NGF (SeV/NGF), brain-derived neurotrophic factor (SeV/BDNF), insulin-like growth factor-1 (SeV/IGF-1) or vascular endothelial growth factor (SeV/VEGF) was injected into the lateral ventricle. Administration of SeV/GDNF, SeV/NGF or SeV/BDNF 30 min after the ischemic insult effectively prevented the delayed neuronal death of the hippocampal CA1 pyramidal neurons. Furthermore, the administration of SeV/GDNF or SeV/NGF as late as 4 or 6 h after the ischemic insult also prevented the death of these neurons. These results indicate that SeV vector-mediated gene transfer of neurotrophic factors has high therapeutic potency for preventing the delayed neuronal death induced by transient global ischemia, and provides an approach for gene therapy of stroke.

IGSF4: a new intercellular adhesion molecule that is called by three names, TSLC1, SgIGSF and SynCAM, by virtue of its diverse function

Members of the immunoglobulin superfamily often play key roles in intercellular adhesion. IGSF4 is a novel immunoglobulin (Ig)-like intercellular adhesion molecule. Three Ig-like domains are included in the extracellular domain of IGSF4 and mediate homophilic or heterophilic interactions independently of Ca2+. The cytoplasmic domain of IGSF4 contains the binding motifs that connect to actin fibers. Since IGSF4 has been characterized by several independent research groups, this molecule is called by three names, TSLC1, SgIGSF and SynCAM. IGSF4 was first characterized as a tumor suppressor of non-small cell lung cancer and termed TSLC1, although how IGSF4 suppresses tumor growth remains unknown. Silencing of the IGSF4 gene was primarily achieved by allelic loss and promoter methylation in this type of cancers. Soon after this discovery, IGSF4 was found to have roles in adhesion of spermatogenic cells to Sertoli cells and mast cells to fibroblasts and termed SgIGSF. Other researchers revealed that IGSF4 drives synaptic formation of neural cells and termed it SynCAM.

A mutation in protein phosphatase type 2A as a cause of melanoma progression

The BL6 subline was derived from the F10 line, which was derived from the B16 mouse melanoma cell line. BL6 cells are more invasive than F10 cells and differ genetically from F10 cells by an alteration of the gene encoding the B56gamma regulatory subunit of protein phosphatase 2A (PP2A). This alteration results in the transcription of mRNA encoding a truncated variant of the B56gamma1 isoform (Delta-gamma-1). Delta-gamma-1 is capable of targeting PP2A to the specific subcellular sites but incapable of promoting the dephosphorylation of specific substrates that is normally mediated by the B56gamma subunit-containing PP2A holoenzyme. It thus appears that activities of this type of holoenzymes decrease in cells expressing Delta-gamma-1. Recently, we found two possible ways how Delta-gamma-1 contributes to the enhanced metastatic potential of BL6 cells. The two ways seemed far away from each other: Delta-gamma-1 influenced both the nuclear and cytoplasmic functions of the cell. In the cytoplasm, Delta-gamma-1 localized at the Golgi complex and accelerated Golgi-mediated vesicle transport. On the other hand, Delta-gamma-1 disturbed the cell-cycle regulation. In response to gamma-irradiation, protein levels of Delta-gamma-1 were markedly increased in BL6 cells. Subsequently the integrity of cell-cycle checkpoint became more aberrant in BL6 cells than that in F10 cells. These two actions of Delta-gamma-1 could results in the enhancement of the malignant phenotypes of melanoma cells, as discussed in this review.

Regionally specific modulation of brain apolipoprotein E in the mouse during the estrous cycle and by exogenous 17β estradiol

Studies have suggested that 17beta estradiol (E2) can modify apolipoprotein E (apoE) expression. The current study determined if apoE protein varied in different regions of the mouse brain as a function of the estrous cycle and if E2 could increase apoE protein expression. In this study apoE concentration was lowest on estrus in the hippocampus, cingulate cortex and frontal cortex. In contrast, apoE concentration was highest on estrus in the olfactory bulb and cerebellum. There were no differences in the striatal apoE expression throughout the estrous cycle. Exogenous E2 significantly raised tissue levels of apoE in the olfactory bulb and cerebellum at 5 days after treatment. There was a slight, but nonsignificant increase in cortical expression of apoE and no change in striatum. Immunocytochemical localization studies found estrogen receptor alpha (ERalpha) and estrogen receptor beta (ERbeta) in cortical neurons and glia. In the cerebellum and olfactory bulb, ERbeta was seen primarily in glia. ERalpha was not observed in the cerebellum and was rare in the olfactory bulb. Neither ERalpha nor ERbeta was seen in the striatum. Our data show regional differences in the production of apoE throughout the estrous cycle. In addition, exogenous E2 has regionally specific effects on apoE expression. Regional variability in apoE production appears to vary as a function of the estrogen receptor subtype.

An attempt to isolate genes responsible for spontaneous and experimental metastasis in the mouse model

Cancer develops and progresses as genetic alterations occur subsequently. Onset process of cancer has become well understood in some types of cancer, such as colorectal cancers. In this process, responsible alterations were identified in numbers of oncogenes such as k-ras, and tumor suppressor genes such as p53, as Vogelstein proposed earlier in the multistage carcinogenesis theory. In contrast, our understanding remains short to draw such an adequate diagram for the process during which cancer becomes more malignant, i.e., metastatic. To examine the molecular basis for this progression step, mouse metastasis models have been established where tumor cell lines are inoculated into mice and metastasize to specific organs. The model using B16 melanoma cells is one of the most developed. BL6 subline, one of the most metastatic, was obtained from F10 subline simply through six rounds of in vitro selection. Nonetheless, BL6 cells metastasize lungs much more heavily than F10 cells when injected subcutaneously. The difference in gene expression between the two sublines is considered rather small but relevant for spontaneous metastasis. We began our research by elaborating a method for the construction of subtracted cDNA libraries, and made it applicable to BL6 and F10 cells. As a result, we were able to isolate a couple of genes that were expressed differently between the two sublines. As might be expected, each of the genes appeared to play a role more or less in distinct aspects of spontaneous metastasis of B16 melanoma cells. Moreover, similar roles were expected for the genes in the process by which human melanoma cells metastasize.

Essential Bacillus subtilis genes

To estimate the minimal gene set required to sustain bacterial life in nutritious conditions, we carried out a systematic inactivation of Bacillus subtilis genes. Among approximately 4,100 genes of the organism, only 192 were shown to be indispensable by this or previous work. Another 79 genes were predicted to be essential. The vast majority of essential genes were categorized in relatively few domains of cell metabolism, with about half involved in information processing, one-fifth involved in the synthesis of cell envelope and the determination of cell shape and division, and one-tenth related to cell energetics. Only 4% of essential genes encode unknown functions. Most essential genes are present throughout a wide range of Bacteria, and almost 70% can also be found in Archaea and Eucarya. However, essential genes related to cell envelope, shape, division, and respiration tend to be lost from bacteria with small genomes. Unexpectedly, most genes involved in the Embden-Meyerhof-Parnas pathway are essential. Identification of unknown and unexpected essential genes opens research avenues to better understanding of processes that sustain bacterial life.

Adenovirus-mediated overexpression of a gene prevents hearing loss and progressive inner hair cell loss after transient cochlear ischemia in gerbils

The use of adenoviral vectors has recently provided a novel strategy for direct gene transfer into the cochlea. In this study, we assessed the utility of an adenoviral vector expressing glial-cell-derived neurotrophic factor (GDNF) in ischemia-reperfusion injury of the gerbil cochlea. The vector was injected through the round window 4 days before ischemic insult. The distribution of a reporter transgene was confirmed throughout the cochlea from the basal to the apical turn and Western blot analysis indicated significant upregulation of GDNF protein 11 days following virus inoculation. Hearing ability was assessed by sequentially recording compound action potentials (CAP), and the degree of hair cell loss in the organ of Corti was evaluated in specimens stained with rhodamine-phalloidin and Hoechst 33342. On the seventh day of ischemia, the CAP threshold shift and inner hair cell loss were remarkably suppressed in the Ad-GDNF group compared with the control group. These results suggest that adenovirus-mediated overexpression of GDNF is useful for protection against hair cell damage, which otherwise eventually occurs after transient ischemia of the cochlea.

Assembly and genetics of spore protective structures

The sporulation program in Bacillus subtilis ends in the formation of a highly resistant endospore that can withstand extremes of heat, mechanical disruption, ultraviolet irradiation, lytic enzymes and chemical attack. These properties are attributed mainly to the unique structure of spore coat and cortex, as well as to the physical state of the spore cytoplasm. The outermost layer of the spore, called the coat, has two morphologically distinct sublayers: an electron-dense outer coat and an electron-translucent inner coat. The coat is composed of more than 2 dozen proteins of varying size. Many coat genes and coat proteins have been isolated and characterized in detail, and studies of these have identified proteins with important roles in coat assembly, resistance and spore germination. We describe here characteristics of the coat proteins and propose a model for coat assembly based on recent work.

Lysosomal storage results in impaired survival but normal neurite outgrowth in dorsal root ganglion neurones from a mouse model of Sandhoff disease

Sandhoff disease is a heritable lysosomal storage disease resulting from impaired degradation of GM2 ganglioside and related substrates. A mouse model of Sandhoff disease created by gene targeting displays progressive neurological manifestations, similar to patients with the disease. In the present in vivo and in vitro studies, we examined morphological and functional abnormalities of dorsal root ganglion (DRG) neurones in Sandhoff disease mice at an asymptomatic stage (approximately 1 month of age). Light microscopic studies with Nissl staining and immunocytochemistry suggested extensive intracytoplasmic storage of GM2 ganglioside in the Sandhoff mouse DRG neurones. These findings were consistent with the results of electron microscopy, in which a huge number of pleomorphic inclusion bodies immunoreactive for GM2 ganglioside were present in the cytoplasm of the neurones. The inclusion bodies were also identified in satellite cells and Schwann cells in the Sandhoff mouse DRG. The survival ratios of DRG neurones after 1, 2, 4 and 6 days in culture were significantly lower in the Sandhoff mice than in the age-matched heterozygous mice. The ratio of neurite-bearing cells on poly-l-lysine-coated dishes after 2 days in culture was also lower by approximately 10% in the Sandhoff mice compared to the heterozygotes, but additional coating of laminin onto poly-l-lysine dramatically enhanced the neurite extension from the neurones in both groups of mice. These results indicate that accumulation of GM2 ganglioside in DRG neurones impairs the capability of the neurones to survive in vitro, although viable neurones from the Sandhoff mice in culture can regenerate neurites nearly as well as unaffected neurones.

Increased expression of a nucleolar Nop5/Sik family member in metastatic melanoma cells: evidence for its role in nucleolar sizing and function

F10 and BL6 cells of B16 mouse melanoma cells are metastatic after intravenous injection, but only BL6 cells can metastasize to lungs after subcutaneous injection. Differences in gene expression between the two cell lines were examined, and a greater expression of the Sik-similar protein (Sik-SP) gene was found in BL6 cells. Structurally, Sik-SP belongs to the nucleolar Nop5/Sik family whose members play central roles in ribosome biogenesis; however, the function of Sik-SP has not been examined. Cytology with green fluorescent protein-fused proteins showed that Sik-SP was localized to the nucleolus. To examine whether Sik-SP is involved in ribosome biogenesis, two parameters were measured: magnitude of ribosomal RNA synthesis per nucleus and magnitude of protein production from the same amount of mRNA of an exogenous luciferase gene. Both values and, in addition, nucleolar size were larger in COS-7 monkey kidney cells overexpressing Sik-SP and BL6 cells than in mock-transfected COS-7 and F10 cells, respectively. Sik-SP seemed to promote ribosome biogenesis in the nucleolus. Furthermore, the expression of Sik-SP seemed to confer a greater cell growth response to serum, because such a response was greater in BL6 cells and F10 cells overexpressing Sik-SP than in untreated and mock-transfected F10 cells. Sik-SP may render melanoma cells more competent to survive through augmenting the activity of nucleolus.

Identification of tumor metastasis suppressor region on the short arm of human chromosome 20

Acquisition of metastatic ability by prostate cancer cells is the hallmark of their lethal trait and outcome. However, the genetic alterations underlying the clinical progression and pathogenesis of prostate cancer are not well understood. Several studies involving loss of heterozygosity (LOH) and comparative genomic hybridization analysis have identified distinctively altered regions on various human chromosomes, and genomic imbalance of chromosome 20 was implicated in progression and recurrence of prostate tumors. To examine the role of chromosome 20 in prostate neoplasms, we introduced this chromosome into highly metastatic rat prostate cancer cells using the microcell-mediated chromosome transfer technique. Introduction of the chromosome resulted in significant suppression of the metastatic ability of the hybrid cells, by as much as 98%, without any interference with the in vivo growth rate or tumorigenicity of primary tumor in SCID mice. Our STS-PCR analysis on 10 hybrid clones indicates that the suppressor activity of chromosome 20 is located in the p11.23-12 region. Further examination of the hybrid clones by experimental metastasis assay and histologic analysis as well as Matrigel invasion assay suggests the involvement of the suppressor region at an early stage of invasion and extravasation. We also investigated the status of the chromosome 20 suppressor region in pathology specimens from human prostate cancer patients and detected the frequent loss of this region in high-grade tumors. These results suggest the presence of a putative suppressor gene on human chromosome 20 that is functionally involved in development of prostate cancer metastases.

Intraventricular administration of recombinant adenovirus to neonatal twitcher mouse leads to clinicopathological improvements

Twitcher mouse is a murine model of human globoid cell leukodystrophy (Krabbe disease), which is characterized by a genetic deficiency in galactocerebrosidase (GALC) activity. The nervous system is affected early and severely by demyelination in the white matter. So far, there is no effective treatment for Krabbe disease except bone marrow transplantation (BMT). However, BMT has inherent limitations such as unavailability of donors and graft-versus-host disease. In this study, we injected recombinant adenovirus encoding GALC into the lateral ventricle of twitcher mice at postnatal day 0 (PND 0) and the therapeutic effects were evaluated. Our results showed slight, but significant improvements in motor functions, body weight and twitching and a prolonged life span. In brain, GALC activity was increased to 15% that of normal littermates and psychosine concentration was decreased to 55% that of untreated twitcher mice at PND 15. The number of PAS-positive globoid cells in brain stem was also reduced significantly at PND 35. In contrast, when adenoviruses were injected to the twitcher mice at PND 15, almost no improvements were observed. These results demonstrate that the timing of treatment may be of great importance in Krabbe disease.

Skeletal muscle regeneration after insulin-like growth factor I gene transfer by recombinant Sendai virus vector

We scrutinized the applicability and efficacy of Sendai virus (SeV) vectors expressing either LacZ or human insulin-like growth factor-I (hIGF-I) in gene transfer into skeletal muscle. Seven days after the intramuscular injection of LacZ/SeV X-gal labeled myofibers were demonstrated in rat anterior tibialis muscle with/without bupivacaine treatment and the transgene expression persisted up to 1 month after injection. Recombinant hIGF-I was detected as a major protein species in culture supernatants of a neonatal rat myoblast cell line L6 and thus induced the cells to undergo myogenetic differentiation. The introduction of hIGF-I/SeV into the muscle showed a significant increase in regenerating and split myofibers which were indicative of hypertrophy, and also an increase in the total number of myofibers, in comparison to that seen in the LacZ/SeV-treated control muscle. These results demonstrate that SeV achieves high-level transgene expression in skeletal muscle, and that hIGF-I gene transfer using SeV vector may therefore have great potential in the treatment of neuromuscular disorders.

Establishment and characterization of immortalized Schwann cells from murine model of Niemann-Pick disease type C (spm/spm)

Niemann-Pick disease type C (NPC) is characterized by an accumulation of unesterified cholesterol in the endosomal/lysosomal (E/L) system, resulting in progressive neurodegeneration and death during early childhood. To investigate the cellular pathomechanism of nervous system involvement in NPC, continuous neural cell lines are desirable. In this study, we obtained neuronal and Schwann cell cultures and established spontaneously immortalized Schwann cell lines from dorsal root ganglia and peripheral nerves of NPC model mouse (spm/spm). One of the cell lines, designated SPMS9, had distinct Schwann cell phenotypes and was maintained over 10 months without phenotypic alterations. The level of Npc1 mRNA was markedly decreased, and NPC1 protein was not detectable in SPMS9 cells. These cells contained intracytoplasmic granules positive for filipin cholesterol staining and immunoreactive for GM2 ganglioside. Electron-microscopically, intracytoplasmic polymorphous membranous inclusions and vacuoles were demonstrated in SPMS9 cells. The treatment with an inhibitor of ceramide-specific glucosyltransferase, N-butyldeoxynojirimysin (NB-DNJ) markedly reduced the intracytoplasmic granular immunofluorescence for GM2 ganglioside in SPMS9 cells, whereas the amount of filipin-positive granules remained unchanged. The SPMS9 cells retained vesicular fluorescence of cationic dye acriflavine 16-24 hours after loading, indicating the defect of transmembrane efflux pump activity of NPC1 in the E/L compartment in these cells. These immortalized Schwann cells can be useful in studies on the nervous system lesions in NPC.

Granulomatous tissue formation of shikon and shikonin by air pouch method

"The extract of shikon" (SK) and shikonin play important roles in the development of granulomatous tissue formation. To reveal the augmenting effect of SK or shikonin on vascular endothelial growth factor (VEGF) production and neovascularization, we investigated murine granulomatous tissue induced by SK and shikonin, comparing them to pouches in which trehalose 6,6'-dimycolate (TDM) was injected. The development of granulomatous tissue formation was evaluated by the wet weight of pouch walls. At day 5 and 7 after SK and shikonin injection, prominent granulomatous tissue formation was detected. Histological observations on the development of granulomatous tissue showed that the pouch was formed in the submuscular connective tissue and necrotic tissue directly facing the cavity and granulomatous tissue developed in the connective tissue. At day 1, VEGF-positive neutrophils accumulated in the pouch wall. Granulomatous tissue formation and neovascularization by injection of SK or shikonin was not more prominent than TDM. However, the present results indicate that SK and shikonin induce neovascularization in granulomatous tissue.

Inhibition of Ras extracellular-signal-regulated kinase (ERK) mediated signaling promotes ciliary neurotrophic factor (CNTF) expression in Schwann cells

Ciliary neurotrophic factor (CNTF) can prevent injury-induced motor neuron death. However, it is also evident that expression of CNTF in Schwann cells is suppressed during nerve regeneration. In this report, we have addressed the mechanism underlying the down-regulation of CNTF expression in injured nerves using a mouse Schwann cell line IMS32 and mouse sciatic nerve. In IMS32 cells, activation of the Ras extracellular-signal-regulated kinase (ERK) pathway by adenoviral vector-mediated expression of dominant active MEK1 did not alter a basal level of CNTF expression, whereas inhibition of the Ras-ERK pathway by using adenoviral vectors resulted in a marked increase in CNTF expression. This inverse relation between before and after axotomy was also observed in mouse sciatic nerve. In the axotomized sciatic nerve, the phosphorylated ERK was markedly increased; in contrast, the expression of CNTF was markedly decreased. These findings suggest that an inactive state of ERK is crucial for the CNTF expression in Schwann cells, and that activation of ERK following nerve injury critically influences the expression of CNTF. This might well explain why CNTF is highly expressed in quiescent Schwann cells in the peripheral nervous system, and also why CNTF is not abundant in axotomized nerves or cultured Schwann cells in which the proliferation signal is obviously active.

Adenoviral gene transfer of glial cell line-derived neurotrophic factor to injured adult motoneurons

Glial cell line-derived neurotrophic factor (GDNF) strongly supports the survival of injured neonatal motoneurons, suggesting its potential uses in the treatment of motoneuron injury and motor neuron diseases. We examined neuroprotective effects of an adenoviral vector encoding GDNF (AxCAhGDNF) on the survival of lesioned adult rat facial and spinal motoneurons. The facial nerve or the seventh cervical segment (C7) ventral and dorsal roots of 3 month-old Fischer 344 male rats were avulsed and removed from the stylomastoid or vertebral foramen, respectively, and AxCALacZ (adenovirus containing beta-galactosidase gene), AxCAhGDNF, or PBS was inoculated in the lesioned foramen. One week after the avulsion and treatment with AxCALacZ, the animal showed expression of beta-galactosidase activity in lesioned facial and spinal motoneurons. Animals avulsed and treated with AxCAhGDNF showed intense immunolabeling for GDNF in lesioned facial and spinal motoneurons and expression of virus-induced human GDNF mRNA transcripts in the lesioned brain stem and spinal cord tissues. The treatment with AxCAhGDNF after avulsion significantly prevented the loss of lesioned facial and C7 spinal motoneurons, ameliorated choline acetyltransferase immunoreactivity, and suppressed the activity of nitric oxide synthase in these neurons. These results indicate that the adenovirus-mediated gene transfer of GDNF may prevent the degeneration of motoneurons in adult humans with motoneuron injury and motor neuron diseases.

Effect of depletion of FtsY on spore morphology and the protein composition of the spore coat layer in Bacillus subtilis

Bacillus subtilis FtsY is a homolog of the alpha-subunit of mammalian signal recognition particle (SRP) receptor, and is essential for protein translocation and vegetative cell growth. An FtsY conditional null mutant (strain ISR39) can express ftsY during the vegetative stage but not during spore formation. Spores of ISR39 have the same resistance to heat and chloroform as the wild-type, while their resistance to lysozyme is reduced. Electron microscopy showed that the outer coat of spores was incompletely assembled. The coat protein profile of the ftsY mutant spores was different from that of wild-type spores. The amounts of CotA, and CotE were reduced in spore coat proteins of ftsY mutant spores and the molecular mass of CotB was reduced. In addition, CotA, CotB, and CotE are present in normal form at T(8) of sporulation in ftsY mutant cells. These results suggest that FtsY has a pivotal role in assembling coat proteins onto the coat layer during spore morphogenesis.

Structure, expression and chromosome mapping of MLZE, a novel gene which is preferentially expressed in metastatic melanoma cells

We isolated a novel gene, termed MLZE, from a B16-BL6 cDNA library after subtraction of B16-F10 mRNA. Expression levels of mouse MLZE (mMLZE) increased in accordance with metastatic ability of B16 melanoma sublines. Human homolog of mMlze (hMlze) contained one leucine zipper structure and two potential nuclear localizing signals. Northern blot analysis of multiple human tissues showed that hMLZE was expressed primarily in trachea and spleen. We mapped the hMLZE gene (by fluorescence in situ hybridization) to 8q24.1 - 2, which contains the c-myc gene and is often amplified in malignant melanoma. Immunohistochemistry revealed that the number of hMlze-positive cases was significantly larger in Clark levels III, IV and V melanomas (6 / 11 = 55%) than in Clark levels I and II melanomas (2 / 15 = 13%). In two cases of hMlze-positive melanomas, the strength of hMlze staining increased substantially in the deep component of the tumor. Considering that melanomas above Clark level II are more metastatic than those below Clark level III, these findings suggested that MLZE is one of the genes whose expression is upregulated during the course of acquisition of metastatic potential in melanoma cells.

Rescue of ischemic brain injury by adenoviral gene transfer of glial cell line-derived neurotrophic factor after transient global ischemia in gerbils

Glial cell line-derived neurotrophic factor (GDNF), a member of the transforming growth factor (TGF)-beta superfamily, is one of the most potent neurotrophic factors and promotes survival of many populations of cells. We examined neuroprotective effect of an adenoviral vector encoding glial cell line-derived neurotrophic factor (AxCAhGDNF) on the transient global ischemia. Gerbils received administration of AxCAhGDNF or an adenoviral vector encoding bacterial beta-galactosidase gene (AxCALacZ) through the lateral ventricle. Two days later, occluding bilateral common carotid arteries for 5 min using aneurysm clips produced the transient global forebrain ischemia. Animals showed intense immunolabeling for GDNF in ependymal cells on 2, 4 and 7 days after the operation. The exogenous gene transducted by adenovirus in the same cells was detected by in situ hybridization. The treatment with AxCAhGDNF significantly prevented the loss of hippocampal CA1 pyramidal neurons 2 to 7 days after the operation, as compared to AxCALacZ treatment. Also terminal deoxynucleotidyl transferase-mediated dUTP-biotin in situ nick end labeling (TUNEL) staining was markedly reduced in the case with AxCAhGDNF treatment at 7 days after the operation. These results indicated that the adenovirus-mediated gene transfer of GDNF might prevent the delayed neuronal death of stroke and other disorders of the cerebral vasculature.

The yabG gene of Bacillus subtilis encodes a sporulation specific protease which is involved in the processing of several spore coat proteins

The synthesis and proteolysis of the spore coat proteins, SpoIVA and YrbA, of Bacillus subtilis were analyzed using antisera. Almost no intact full-length proteins of either type were extracted from wild-type spores, while yabG mutant spores contained intact SpoIVA and YrbA proteins. We purified recombinant YrbA and YabG proteins from Escherichia coli transformants and found that YrbA was cleaved to the smaller moiety in the presence of YabG in vitro. These observations indicate that YabG is a protease involved in the proteolysis and maturation of SpoIVA and YrbA proteins, conserved with the cortex and/or coat assembly by B. subtilis.

Synthesis and characterization of the spore proteins of Bacillus subtilis YdhD, YkuD, and YkvP, which carry a motif conserved among cell wall binding proteins

We have previously reported that YaaH and YrbA are spore proteins of Bacillus subtilis that are required for spore resistance and/or germination and that they have a motif conserved among so-called cell wall binding proteins [Kodama et al. (1999) J. Bacteriol. 181, 4584-4591, Takamatsu et al. (1999) J. Bacteriol. 181, 4986-4994]. In this study, we analyzed the expression of ydhD, ykuD, and ykvP genes, which encode putative proteins containing the same motif. Transcription of ydhD was dependent on SigE, and the mRNA was detectable from 2 h after the cessation of logarithmic growth (T(2) of sporulation). ykuD was transcribed by SigK RNA polymerase from T(4) of sporulation. Both SigK and GerE were essential for ykvP expression, and this gene was transcribed from T(5) of sporulation. Inactivation of these genes by insertion of an erythromycin resistance gene did not affect vegetative growth, spore resistance to heat, chloroform, and lysozyme, or spore germination in the presence of L-alanine or in a mixture of L-asparagine, D-glucose, D-fructose, and potassium chloride. The His tag fusions of YdhD, YkuD, and YkvP downstream of their natural promoter regions were introduced into a multicopy plasmid. These fusion proteins were produced during sporulation in B. subtilis transformants and were detected in mature spores, indicating that YdhD, YkuD, and YkvP are all proteins intrinsic to spores. Excessive YkuD and YkvP in the sporulating cells did not affect spore resistance or germination. The cells producing excessive YdhD also did not show impaired spore resistance, but their germination properties were changed: the spores revealed reduced response to L-alanine and some of them germinated even without germinants. Escherichia coli b-lactamase, whose signal sequence had been genetically replaced by the cell wall binding motif of YaaH, was produced in sporulating cells, and Western blot analysis indicated that the fused protein was assembled into spores. We speculate that the conserved motif functions as a kind of signal sequence involved in assembly of these proteins on forespores.

Localization of a novel tumor metastasis suppressor region on the short arm of human chromosome 2

Much of the lethality of malignant neoplasms is attributable directly to their ability to develop secondary growths in organs at a distance from the primary tumor mass, whereas few patients die from their primary neoplasm. Little is known about the molecular mechanism of tumor metastasis, however, which is controlled by a variety of positive and negative factors. In the search for metastasis suppressor genes, we have used the microcell-mediated chromosome transfer method and a rat prostate tumor model in SCID mice. When human chromosome 2 was introduced into the highly metastatic rat prostatic tumor cell, AT6.1, the metastatic ability of this cell was significantly (>99%) decreased in animals. An STS-based PCR analysis for 8 hybrid clones indicates that the suppressor activity is located in the p25-22 region of the chromosome. Furthermore, the AT6.1 cell with human chromosome 2 showed a reduced ability to invade Matrigel, suggesting that the suppressor activity is involved in the step of tumor invasion during the progression of prostate cancer. We have also examined the status of the suppressor region on chromosome 2 in human prostate cancer specimens and found that this region was often lost in high-grade tumors. These results suggest that the putative suppressor gene on chromosome 2 is functionally involved in the progression of human prostate cancer. Genes Chromosomes Cancer 28:285-293, 2000.

Activation of the tumor metastasis suppressor gene, KAI1, by etoposide is mediated by p53 and c-Jun genes

KAI1 is a metastasis suppressor gene which is capable of inhibiting the processes of tumor metastasis without affecting tumorigenicity per se. We found that etoposide, a topoisomerase II inhibitor, is able to activate the expression of the KAI1 gene in a dose-dependent manner in human prostate cancer cell lines, ALVA, DU145, and PC-3 as well as in human lung carcinoma cell A549. The activation of the KAI1 gene was mainly mediated by the c-Jun gene in the PC-3 and DU145 cell lines, while it was mediated by both p53 and c-Jun genes in the A549 cell line. These results suggest that the augmentation of the KAI1 gene expression is independently controlled by p53 and c-Jun at the transcriptional level in the human cancer cell lines. Furthermore, treatment of these cell lines with etoposide resulted in significant reduction of cellular invasion measured by the Matrigel invasion chamber. Because etoposide has been shown to be effective on advanced prostate cancer when used in combination with other regimens, our results provide further rationale to use this drug as an antimetastatic agent.