[RNA-interference, induced by transient and continuous expression of hairpin RNA in cells from Drosophila and mammals]

RNA interference (RNAi) may be induced by a plasmid with an inverted repeat (IR) sequence directing transcription of hairpin-type double-stranded RNA (dsRNA). This study examines the effects of changing various parameters of IR constructs on Drosophila and mammalian RNAi, using the dual luciferase system, RNAi activity was found to vary depending on IR length ass well as the length and sequence of the internal loop separating sense and antisense sequences. Both transient and stable RNAi occurred in Drosophila cultured cells. Although transient DNA-mediated RNAi was noted in most mammalian cells, no mammalian cells stably possessing IR sequences and hence RNAi activity could be obtained. In Drosophila, DNA-mediated RNAi was considerably weaker than long-dsRNA-mediated RNAi. The cytological data indicated that this was most probably caused by abortive processing of hairpin RNA produced within cells. DNA-mediated RNAi was examined at the level of Drosophila individuals using extramacrochaetae as a model gene, and the presence of an intron sequence in the single-stranded loop region was shown to be essential for effective RNAi.

Activation-induced cytidine deaminase expression in follicular lymphoma: association between AID expression and ongoing mutation in FL

Activation-induced cytidine deaminase (AID) is required for somatic hypermutation (SHM) and class switch recombination (CSR) of the immunoglobulin (Ig) gene. AID has been reported to be specifically expressed in the germinal center (GC). Follicular lymphoma (FL) cells are known to be exposed to GC reaction, as characterized by a high degree of SHM with some heterogeneity in terms of intraclonal microheterogeneity and antigen selection. The heterogeneity of SHM pattern in FL intrigued us to investigate the AID expression. AID expression was investigated in 19 FL materials consisting of 15 cases of FL fresh cells and four cell lines. In all, 10 fresh cells and three cell lines expressed AID, but the others did not. SHM was investigated in 12 fresh cells and four cell lines. The ongoing mutation was significantly different between AID-positive and AID-negative FL fresh cells (unpaired Student's t-test, P=0.047). Ongoing mutation was not seen in any of the cell lines. AID expression was associated with the ongoing mutation in FL fresh cells (two-tailed Pearson's coefficient correlation, r=0.899, P=0.01). The switch off of AID expression may start in the B-lineage differentiation stage counterpart of FL after optimizing SHM, indicated by the cessation of the ongoing mutation in AID-negative FL fresh cells.

Guidelines for the selection of highly effective siRNA sequences for mammalian and chick RNA interference

In the present study, the relationship between short interfering RNA (siRNA) sequence and RNA interference (RNAi) effect was extensively analyzed using 62 targets of four exogenous and two endogenous genes and three mammalian and Drosophila cells. We present the rules that may govern siRNA sequence preference and in accordance with which highly effective siRNAs essential for systematic mammalian functional genomics can be readily designed. These rules indicate that siRNAs which simultaneously satisfy all four of the following sequence conditions are capable of inducing highly effective gene silencing in mammalian cells: (i) A/U at the 5' end of the antisense strand; (ii) G/C at the 5' end of the sense strand; (iii) at least five A/U residues in the 5' terminal one-third of the antisense strand; and (iv) the absence of any GC stretch of more than 9 nt in length. siRNAs opposite in features with respect to the first three conditions give rise to little or no gene silencing in mammalian cells. Essentially the same rules for siRNA sequence preference were found applicable to DNA-based RNAi in mammalian cells and in ovo RNAi using chick embryos. In contrast to mammalian and chick cells, little siRNA sequence preference could be detected in Drosophila in vivo RNAi.

A novel approach to the synthesis of oligodeoxyribonucleotide boranophosphates

Deoxyribonucleoside 3'-boranophosphate derivatives including adenine, cytosine, guanine, and thymine bases were synthesized in good yields by the use of a new boranophosphorylation reaction. The reaction was found to be effective for the formation of internucleotidic boranophosphate linkages.

Stereoselective synthesis of dinucleoside phosphorothioate using enantiopure 1,2-amino alcohols as chiral auxiliaries

Diastereopure nucleoside 3'-cyclic phosphoramidites were synthesized stereoselectively from enantiopure 1,2-amino alcohols. In the presence of a novel activator, these phosphoramidites underwent the condensation with 3'-O-tert-butyldimethylsilylthymidine to give the corresponding phosphite intermediates. Upon sulfurization, followed by deprotection, dithymidine phosphorothioate was obtained in good yield with good to excellent diastereoselectivity.

Synthesis of a new type of artificial nucleic acid derived from optically active serine

This paper describes the synthesis of a new type of nucleic acid analog derived from L-serine with ester linkages. The monomer unit bearing thymine base was synthesized from L-serine ethyl ester by a three-step reaction in good yield without racemization. 3-Nitro-1,2,4-triazol-1-yl-tris(pyrrolidin-1-yl)phosphonium hexafluorophosphate (PyNTP) was found to be highly effective for the rapid ester bond formation without racemization. 2-Phenyl-2-(trimethylsilyl)ethyl group was successfully employed as a carboxyl protecting group in solution-phase synthesis.

Novel taurine-containing uridine derivatives and mitochondrial human diseases

Two novel modified uridines were identified from mammalian mitochondrial (mt) tRNAs. Mass spectrometric analysis revealed that they are modified uridines possessing a sulfonic acid group derived from taurine; 5-taurinomethyl-uridine from mt tRNAs for Trp and Leu(UUR), and 5-taurinomethyl-2-thiouridine from mt tRNAs for Lys, Gln and Glu. We have found lack of modification of these taurine-containing uridines in mutant mt tRNAs for Leu(UUR) and Lys from pathogenic cells of mitochondrial encephalomyopathies, MELAS and MERRF, respectively.

Acute lymphoblastic leukemia accompanied by chromosomal abnormality of translocation (12;17)

This report concerns a female patient with B-precursor acute lymphoblastic leukemia with concomitant expression of CD13 and CD33. A rare chromosomal abnormality, t(2;17)(p13:q21), was detected in 70% of metaphases analyzed. A new subgroup of acute leukemia is proposed, consisting of our case and 12 reported cases with similar chromosomal abnormalities. This subgroup has a poor prognosis and a high incidence of biphenotypic characteristics.

Molecular cloning and identification of 3'-phosphoadenosine 5'-phosphosulfate transporter

Nucleotide sulfate, namely 3'-phosphoadenosine 5'-phosphosulfate (PAPS), is a universal sulfuryl donor for sulfation. Although a specific PAPS transporter is present in Golgi membrane, no study has reported the corresponding gene. We have identified a novel human gene encoding a PAPS transporter, which we have named PAPST1, and the Drosophila melanogaster ortholog, slalom (sll). The amino acid sequence of PAPST1 (432 amino acids) exhibited 48.1% identity with SLL (465 amino acids), and hydropathy analysis predicted the two to be type III transmembrane proteins. The transient expression of PAPST1 in SW480 cells showed a subcellular localization in Golgi membrane. The expression of PAPST1 and SLL in yeast Saccharomyces cerevisiae significantly increased the transport of PAPS into the Golgi membrane fraction. In human tissues, PAPST1 is highly expressed in the placenta and pancreas and present at lower levels in the colon and heart. An RNA interference fly of sll produced with a GAL4-UAS system revealed that the PAPS transporter is essential for viability. It is well known that mutations of some genes related to PAPS synthesis are responsible for human inherited disorders. Our findings provide insights into the significance of PAPS transport and post-translational sulfation.

Proteoglycan UDP-galactose:beta-xylose beta 1,4-galactosyltransferase I is essential for viability in Drosophila melanogaster

Heparan and chondroitin sulfates play essential roles in growth factor signaling during development and share a common linkage tetrasaccharide structure, GlcAbeta1,3Galbeta1,3Galbeta1,4Xylbeta1-O-Ser. In the present study, we identified the Drosophila proteoglycan UDP-galactose:beta-xylose beta1,4-galactosyltransferase I (dbeta4GalTI), and determined its substrate specificity. The enzyme transferred a Gal to the -beta-xylose (Xyl) residue, confirming it to be the Drosophila ortholog of human proteoglycan UDP-galactose:beta-xylose beta1,4-galactosyltransferase I. Then we established UAS-dbeta4GalTI-IR fly lines containing an inverted repeat of dbeta4GalTI ligated to the upstream activating sequence (UAS) promoter, a target of GAL4, and observed the F(1) generation of the cross between the UAS-dbeta4GalTI-IR fly and the Act5C-GAL4 fly. In the F(1), double-stranded RNA of dbeta4GalTI is expressed ubiquitously under the control of a cytoplasmic actin promoter to induce the silencing of the dbeta4GalTI gene. The expression of the target gene was disrupted specifically, and the degree of interference was correlated with phenotype. The lethality among the progeny proved that beta4GalTI is essential for viability. This study is the first to use reverse genetics, RNA interference, to study the Drosophila glycosyltransferase systematically.

Functional subdivision of trunk visceral mesoderm parasegments in Drosophila is required for gut and trachea development

In Drosophila, trunk visceral mesoderm, a derivative of dorsal mesoderm, gives rise to circular visceral muscles. It has been demonstrated that the trunk visceral mesoderm parasegment is subdivided into at least two domains by connectin expression, which is regulated by Hedgehog and Wingless emanating from the ectoderm. We now extend these findings by examining a greater number of visceral mesodermal genes, including hedgehog and branchless. Each visceral mesodermal parasegment appears to be divided into five or six regions, based on differences in expression patterns of these genes. Ectodermal Hedgehog and Wingless differentially regulate the expression of these metameric targets in trunk visceral mesoderm. hedgehog expression in trunk visceral mesoderm is responsible for maintaining its own expression and con expression. hedgehog expressed in visceral mesoderm parasegment 3 may also be required for normal decapentaplegic expression in this region and normal gastric caecum development. branchless expressed in each trunk visceral mesodermal parasegment serves as a guide for the initial budding of tracheal visceral branches. The metameric pattern of trunk visceral mesoderm, organized in response to ectodermal instructive signals, is thus maintained at a later time via autoregulation, is required for midgut morphogenesis and exerts feedback effect on trachea, ectodermal derivatives.

Short-interfering-RNA-mediated gene silencing in mammalian cells requires Dicer and eIF2C translation initiation factors

RNA interference (RNAi) is the process of long, double-stranded (ds), RNA-dependent posttranscriptional gene silencing (PTGS). In lower eukaryotes, dsRNA introduced into the cytoplasm is cleaved by the RNaseIII-like enzyme, Dicer, to 21-23 nt RNA (short interfering [si] RNA), which may serve as guide for target mRNA degradation. In mammals, long-dsRNA-dependent PTGS is applicable only to a limited number of cell types, whereas siRNA synthesized in vitro is capable of effectively inducing gene silencing in a wide variety of cells. Although biochemical and genetic analyses in lower eukaryotes showed that Dicer and some PIWI family member proteins are essential for long-dsRNA-dependent PTGS, little is known about the molecular mechanisms underlying siRNA-based PTGS. Here, we show that Dicer and eIF2C translation initiation factors belonging to the PIWI family (eIF2C1-4) play an essential role in mammalian siRNA-mediated PTGS, most probably through synergistic interactions. Immunoprecipitation experiments suggest that, in human and mouse cells, complex formation occurs between Dicer and eIF2C1 or 2 and that the PIWI domain of eIF2C is essential for the formation of this complex.

Usefulness of automatic detection of fragmented red cells using a hematology analyzer for diagnosis of thrombotic microangiopathy

We previously reported an automatic method for quantitative analysis of schistocytes or fragmented red cells using an automatic hematology analyzer, XE-2100. In the study reported here, we evaluated the accuracy of this detection method in patients with thrombotic microangiopathy (TMA). A follow-up study was performed on 14 patients with two types of TMA, thrombotic thrombocytopenic purpura or hemolytic uremic syndrome. Schistocyte percent was evaluated both with an automatic counter and by means of microscopic observation. Total activity and isoenzyme pattern of lactate dehydrogenase (LD) were also determined. In these patients, schistocyte percent determined by automatic counting correlated highly with that determined by manual counting under microscopic observation (r = 0.852, P < 0.0001). Schistocyte percent was shown to correlate significantly with isoenzyme fractions 1 and 2 of LD (r = 0.732, P < 0.02), reflecting hemolysis. Nine of 11 patients tested had high concentrations of LD isoenzyme five without distinct liver damage, and schistocyte percent did not relate to fraction 5 of LD. Automatic detection of schistocyte percent using a hematology analyzer was useful for an accurate diagnosis and follow-up of thrombotic microangiopathy. The origin of LD fraction 5 remains to be determined.

Requirements of high levels of Hedgehog signaling activity for medial-region cell fate determination in Drosophila legs: identification of pxb, a putative Hedgehog signaling attenuator gene repressed along the anterior-posterior compartment boundary

We show that high levels of Hedgehog signaling activity are essential for medial-region patterning in Drosophila legs. In mid-to-late third instar leg discs, high levels of Hedgehog signals repress the transcription of pxb, a newly identified gene encoding a transmembrane protein expressed specifically in the anterior compartment. Misexpression experiments indicate that Pxb may serve as a Hedgehog signaling attenuator capable of acting prior to Hedgehog-Patched interactions, suggesting that Hedgehog signaling in leg discs includes a pxb-repression-mediated positive feedback loop. RNA interference and clonal analysis show that neither Wingless nor Decapentaplegic signaling is required for pxb repression but high levels of Wingless signaling activity are essential for patterning in the leg ventral medial region.

Inducible expression of double-stranded RNA reveals a role for dFADD in the regulation of the antibacterial response in Drosophila adults

In Drosophila, the immune deficiency (Imd) pathway controls antibacterial peptide gene expression in the fat body in response to Gram-negative bacterial infection. The ultimate target of the Imd pathway is Relish, a transactivator related to mammalian P105 and P100 NF-kappaB precursors. Relish is processed in order to translocate to the nucleus, and this cleavage is dependent on both Dredd, an apical caspase related to caspase-8 of mammals, and the fly Ikappa-B kinase complex (dmIKK). dTAK1, a MAPKKK, functions upstream of the dmIKK complex and downstream of Imd, a protein with a death domain similar to that of mammalian receptor interacting protein (RIP). Finally, the peptidoglycan recognition protein-LC (PGRP-LC) acts upstream of Imd and probably functions as a receptor for the Imd pathway. Using inducible expression of dFADD double-stranded RNA, we demonstrate that dFADD is a novel component of the Imd pathway: dFADD double-stranded RNA expression reduces the induction of antibacterial peptide-encoding genes after infection and renders the fly susceptible to Gram-negative bacterial infection. Epistatic studies indicate that dFADD acts between Imd and Dredd. Our results reinforce the parallels between the Imd and the TNF-R1 pathways.

Ligand-dependent activation of breathless FGF receptor gene in Drosophila developing trachea

Spatially and temporally regulated activity of Branchless/Breathless signaling is essential for trachea development in Drosophila. Early ubiquitous breathless (btl) expression is controlled by binding of Trachealess/Tango heterodimers to the btl minimum enhancer. Branchless/Breathless signaling includes a Sprouty-dependent negative feedback loop. We show that late btl expression is a target of Branchless/Breathless signaling and hence, Branchless/Breathless signaling contains a positive feedback loop, which may guarantee a continuous supply of fresh receptors to membranes of growing tracheal branch cells. Branchless/Breathless signaling activates MAP-kinase, which in turn, activates late btl expression and destabilizes Anterior-open, a repressor for late btl expression. Biochemical and genetic analysis indicated that the minimum btl enhancer includes binding sites of Anterior-open.

Fluctuations in plasma macrophage colony-stimulating factor levels during autologous peripheral blood stem cell transplantation for haematologic diseases

Plasma macrophage colony-stimulating factor (M-CSF) levels were measured in 13 haematologic patients treated with autologous peripheral blood stem cell transplantation (PBSCT). Six of the patients showed an increase in M-CSF peak levels (>3000 pg/ml) during the conditioning and stem cell infusion period. The peak levels of M-CSF in this phase correlated with thrombomodulin levels, indicating the endothelial origin of plasma M-CSF. However, the M-CSF levels were not influenced by TNFalpha. More patients with high M-CSF levels (>5000 pg/ml) suffered from organ failure than those with lower M-CSF levels. These results suggest that high M-CSF levels may correlate with cellular or organ damage in patients treated with PBSCT.

Arterio-portal shunt in liver rescued by hepatectomy after arterial embolization

Arterio-portal shunts are generally treated with transcatheter arterial embolization, as a therapeutic measure for bleeding of esophageal varices. However, transcatheter arterial embolization is frequently associated with reestablishment of arterio-portal shunts. We now report our experience with partial hepatectomy to remove the arterio-portal shunt associated with esophageal varices, which recurred after transcatheter arterial embolization. The patient was a 60-year-old female, who had massive hematemesis caused by rupture of esophageal varices. Doppler sonography and arteriography demonstrated an arterio-portal shunt in the right anterior superior segment of the liver. Temporary hemostasis was achieved with transcatheter arterial embolization, however, hemorrhage recurred one month later. The second transcatheter arterial embolization failed to manage the shunt and varices. The patient developed hepatic coma. After recovery from coma, she was referred to our hospital. We carried out partial hepatectomy, which provided remarkable hemodynamic improvement; the portal vein flow changed from hepatofugal to hepatopetal. Esophageal varices and hepatic coma have totally disappeared. This patient has had no complaint and has remained free of esophageal varices, for 3 years postoperatively. She is having a normal life. The partial hepatectomy to remove the arterio-portal shunt induced complete resolution of the arterio-portal shunt, as well as dramatic improvement in portal flow and hepatic coma. Our experience in the present case suggests that partial hepatectomy should be considered as a radical therapy for arterio-portal shunt, without insistence on transcatheter arterial embolization.

Diversification of cell types in the Drosophila eye by differential expression of prepattern genes

According to Freeman (Development, 124 (1997) 261), reiterative use of Spitz signals emanating from already differentiated ommatidial cells triggers the differentiation of around ten different types of cells. Here we show evidence that the choice of cell fate by newly recruited ommatidial cells strictly depends on their developmental potential. Using forced expression of a constitutively active form of Ras1, three developmental potentials (rough, seven-up, and prospero expression) were visualized as relatively narrow bands corresponding to regions where rough-, seven-up- or prospero-expressing ommatidial cells would normally form. Ras1-dependent expression of ommatidial marker genes was regulated by a combinatorial expression of eye prepattern genes such as lozenge, dachshund, eyes absent, and cubitus interruptus, indicating that developmental potential formation is governed by region-specific prepattern gene expression.

Identification of human cancer-related genes by naturally occurring Hepatitis B Virus DNA tagging

Proviral tagging has been used in animals as a powerful tool for cancer genetics. We show that a similar approach is possible in patients with hepatocellular carcinoma (HCC) infected by Hepatitis B Virus (HBV), a human pararetrovirus which may act by insertional mutagenesis. In this work, the HBV genome is used as a probe to identify cancer-related genes. By using HBV-Alu-PCR, we obtained 21 HBV/cellular DNA junctions from 18 different patients. In six of 21, we found the HBV DNA integrated into a cellular gene: (1) Sarco/Endoplasmic Reticulum Calcium ATPase1 Gene; (2) Thyroid Hormone Receptor Associated Protein 150 alpha Gene; (3) Human Telomerase Reverse Transcriptase Gene; (4) Minichromosome Maintenance Protein (MCM)-Related Gene; (5) FR7, a new gene expressed in human liver and cancer tissues; and (6) Nuclear Matrix Protein p84 Gene. Seven junctions contained unique cellular sequences. In the remaining eight, the HBV DNA was next to repetitive sequences, five of them of LINE1 type. The cellular genes targeted by HBV are key regulators of cell proliferation and viability. Our results show that studies on HBV-related HCCs allow to identify cellular genes involved in cancer. We therefore propose this approach as a valuable tool for functional cancer genomic studies in humans.

Clinical characteristics of B-cell lymphoma-associated hemophagocytic syndrome (B-LAHS): comparison of CD5+ with CD5- B-LAHS

OBJECTIVE

B-cell lymphoma-associated hemophagocytic syndrome (B-LAHS) has been increasingly reported in Asia and is regarded as a variant of intravascular lymphomatosis (IVL). Recently CD5 was reported to be expressed in some cases of diffuse large cell lymphoma and IVL. We therefore examined the expression of CD5 on lymphoma cells in B-LAHS and compared the clinical and laboratory data between CD5+ and CD5- B-LAHS.

METHODS

The expression of CD5 on lymphoma cells was examined using flow cytometry and immunohistochemical analysis of paraffin sections. The clinical records were reviewed to characterize clinical features.

PATIENTS

Twelve patients with B-LAHS; ten men and two women, age ranging from 41 to 82 years (median, 63.5 years) were included in this study.

RESULTS

B-LAHS is characterized by fever and hepatosplenomegaly without lymphadenopathy at the initial presentation. Histological examination showed hemophagocytosis and infiltration of lymphoma cells in the bone marrow, and in some cases intravascular proliferation of lymphoid cells characteristic of IVL. All patients showed increased levels of lactate dehydrogenase, C-reactive protein, ferritin and soluble interleukin-2 receptor. In eight of the twelve patients, lymphoma cells were positive for CD5. But no differences were observed in the clinical or laboratory findings between CD5+ B-LAHS and CD5- B-LAHS.

CONCLUSION

No clinical differences were observed between CD5+ B-LAHS and CD5- B-LAHS. Further studies are required to elucidate the differences in pathogenesis between these two subgroups of B-LAHS.

Tetrasomy 21 as the sole acquired karyotypic abnormality in acute myeloblastic leukemia

Peripheral blood and bone marrow analysis of a 79-year-old female led to a diagnosis of acute myeloblastic leukemia with differentiation (AML-M2). Chromosome analysis of the unstimulated bone marrow cells revealed 48, XX,+21,+21, and tetrasomy 21 was the sole cytogenetic abnormality in this constitutionally normal female patient.