The occurrence of various collagen diseases in one family: a sister with ISSc, PBC, APS, and SS and a brother with systemic lupus erythematosus

We encountered siblings who had collagen diseases and related symptoms. Case 1 was a 53-year-old woman who had limited cutaneous systemic sclerosis (ISSc) associated with primary biliary cirrhosis (PBC), antiphospholipid antibody syndrome (APS), and subclinical Sjögren's syndrome (SS). Case 2 was a 48-year-old man, her younger brother, with systemic lupus erythematosus (SLE) that developed at 32 years of age. Investigation of their family revealed that their mother had Raynaud's phenomenon, arthritis, and subclinical Sjögren's syndrome, and that another younger brother of Cases 1 and 2 had Raynaud's phenomenon and general fatigue. HLA analysis revealed that the sister and brother had some identical HLA antigens in common, including A2, A33 (19), B67, B44 (12), Cw7, DR2, DR6, DR52, and DQ1. The sister, brother and their mother had common HLA antigens including A2, B67, Cw7, DR2, and DQ1. Although Cases 1 and 2 shared the same HLA system, they presented different phenotypes of collagen disease.

Differential scanning calorimetry of light meromyosin fragments having various lengths of carp fast skeletal muscle isoforms

Various recombinant light meromyosin (LMM) fragments were prepared from cDNAs encoding the 10 degrees C and 30 degrees C types of myosin heavy chain isoforms predominantly expressed in fast skeletal muscles of the 10 degrees C- and 30 degrees C-acclimated carp, respectively. These included three kinds of quarter fragments, 1/4-, 2/4-, and 4/4-quarter, composed of residues 1-130, 131-270, and 401-563 from the N-terminus, respectively, as well as three halves, N-, M-, and C-half fragments, containing residues 1-301, 131-400, and 302-563, respectively, and 69K fragments of residues 1-525. Unfortunately, in spite of extensive efforts, the 3/4-quarter fragment was not expressed for both 10 degrees C and 30 degrees C types in our expression system using Escherichia coli. All the LMM fragments except for the 10- and 30-2/4 quarters for the 10 degrees C and 30 degrees C types, respectively, exhibited a typical pattern of a-helix in CD spectrometry. When these were subjected to differential scanning calorimetry (DSC), 30 degrees C-type LMM fragments were all found to be more thermostable than the 10 degrees C-type counterparts. To identify amino acid substitutions responsible for different thermostabilities between the 10 degrees C- and 30 degrees C-type LMMs, six mutant proteins were prepared, mainly focusing on substitutions in the C-terminal half of LMM, and subjected to DSC and CD analyses. For three mutants in which two residues of the 10 degrees C type were replaced by those of the 30 degrees C type, 10-S355T/T361A, 10-M415L/L417V, and 10-S535A/H536Q, the endothermic peaks in DSC increased by 1.4-2.0 degrees C from that of the original 10 degrees C type. The T(m) values for two single-residue substitutions, 10-H449R and 10-T491I, shifted 0.8 and 1.3 degrees C higher than that for the 10 degrees C-type LMM, respectively, whereas the last mutant, 10-G61V, showed no change in thermostability. The finding that the difference in T(m) values for major endothermic peaks from the 10-69K and 30-69K fragments was 4.6 degrees C, which roughly corresponds to that between the original 10 degrees C and 30 degrees C types, suggested that the eight substitutions located in the C-terminal region of the 69K fragments (residues 302-525) are major candidates for the residues responsible for the difference in thermostability between the 10 degrees C- and 30 degrees C-type LMMs.

New gamma-fluoromethotrexates modified in the pteridine ring: synthesis and in vitro immunosuppressive activity

Our continuing program to develop new antifolate drugs useful against rheumatoid arthritis led us to modify the pteridine ring of gamma-fluoromethotrexate. Pyrrolopyrimidine derivatives 1e and 1t were found to exhibit potent suppressive effects on the responses of both T and B cells to mitogens, although tetrahydropyridopyrimidine derivatives 2e and 2t and quinazoline derivatives 3e, 3t and 4e showed very weak suppressive activities. Thus, conversion of the pteridine ring of gamma-fluoromethotrexate to a pyrrolopyrimidine ring led to a new potential antirheumatic compound.

Two proline-rich nuclear localization signals in the amino- and carboxyl-terminal regions of the Borna disease virus phosphoprotein

Borna disease virus (BDV) uses a unique strategy of replication and transcription which takes place in the nucleus, unlike other known, nonsegmented, negative-stranded RNA viruses of animal origin. In this process, viral constituents necessary for replication must be transported to the nucleus from the cytoplasm. We report here the evidence that BDV P protein, which may play an important role in viral replication and transcription, is transported into the nucleus in the absence of other viral constituents. This transportation is accomplished by its own nuclear localization signals (NLSs), which are present in both N-terminal (29PRPRKIPR36) and C-terminal (181PPRIYPQLPSAPT193) regions of the protein. These two NLSs can function independently and both have several Pro residues as key amino acids.

Thermal unfolding of three acclimation temperature-associated isoforms of carp light meromyosin expressed by recombinant DNAs

Differential scanning calorimetry (DSC) was performed to investigate thermodynamic properties of three carp fast skeletal light meromyosin (LMM) isoforms expressed in Escherichia coli by recombinant DNAs. Three isoforms were the 10 degreesC-, intermediate-, and 30 degreesC-type LMM predominantly expressed in carp acclimated to 10, 20, and 30 degreesC. The isoforms expressed in E. coli by recombinant DNAs exhibited a typical pattern of alpha-helix in CD spectroscopy with two minima at 222 and 208 nm. Moreover, the three isoforms formed paracrystals typical of LMM, suggesting that expressed proteins retained intact structural properties. When the LMM isoforms were subjected to DSC analysis, the 10 degreesC and 30 degreesC types showed endotherms having transition temperatures (Tm) at 35.1 and 39.5 degreesC, respectively, which are responsible for thermal unfolding of alpha-helix. The intermediate type exhibited two comparable endotherms with Tm values at 34.9 and 40.6 degreesC, implying that it has intermediate thermodynamic properties between those of 10 degreesC and 30 degreesC types. However, a chimeric LMM having the 10 degreesC and 30 degreesC type as N- and C-terminal halves, respectively, showed the DSC pattern typical of the whole 30 degreesC-type molecule. On the other hand, another chimeric LMM composed of the N-terminal 30 degreesC type and C-terminal 10 degreesC type gave the pattern of the full 10 degreesC type. These results suggest that thermodynamic properties of the C-terminal half largely account for thermal unfolding of the whole molecule.

A novel Rab GTPase, Rab33B, is ubiquitously expressed and localized to the medial Golgi cisternae

Small GTP-binding proteins of the Rab family play important roles at defined steps of vesicular transport in protein secretion and the endocytosis pathway. In mammals, more than 30 proteins belonging to the Rab family have been reported to date. We report here the molecular cloning and characterization of a novel Rab protein, Rab33B. The amino acid sequence of Rab33B shows 55.3% identity to the Rab33A protein (previously called S10), and these two proteins share unique amino acid sequences at the effector domain. The genomic organization of rab33B was the same as rab33A: it consists of two exons. Thus, these two proteins make a subclass within the Rab family. Northern blot analysis showed that rab33B is expressed ubiquitously in mouse tissues, in contrast to rab33A whose expression is restricted to the brain and the immune system. A 26 kDa protein was detected by western blotting using a Rab33B-specific monoclonal antibody. Using immunofluorescence studies, Rab33B was shown to co-localize with (alpha)-mannosidase II, a Golgi-specific marker. Immunoelectron microscopy analysis further defined the localization of Rab33B to the medial Golgi cisternae. These results suggest Rab33B plays a role in intra-Golgi transport.

Nuclear targeting activity associated with the amino terminal region of the Borna disease virus nucleoprotein

The Borna disease virus (BDV) replicates in the nucleus. The viral p40 protein (N), which is found abundantly in the nucleus in BDV-infected cells, may play an important role in virus replication. To analyze the amino acid residues involved in the nuclear targeting of BDV N, a series of eukaryotic expression plasmids encoding deletion mutants of N was constructed and transfected into COS-7 cells. In indirect immunofluorescence assays with a rabbit anti-BDV N antiserum, wild-type N was located in the nucleus of transfected cells in the absence of other viral constituents. In contrast, mutants lacking the 13 NH2-terminal amino acid residues 1MPPKRRLVDDADA13 in common gave a cytoplasmic localization pattern. Similarly, a mutant with substitution of 4KRR6 by 4NSG6 was retained in the cytoplasm. Furthermore, a nonapeptide, 3PKRRLVDDA11, derived from the NH2-terminal region of N conferred nuclear targeting activity to beta-galactosidase, which normally resides in the cytoplasm. Thus, we have identified the nuclear targeting signal of the BDV N and narrowed it to the NH2-terminal region where 4KRR6 basic amino acid residues are located.

Interaction of pigeon cytochrome c-(43-58) peptide analogs with either T cell antigen receptor or I-Ab molecule

We determined that a pigeon cytochrome c-derived peptide, p43-58, possesses two anchor residues, 46 and 54, for binding with the I-Ab molecule that are compatible to the position 1 (P1) and position 9 (P9) of the core region in the major histocompatibility complex (MHC) class II binding peptides, respectively. In the present study to analyze each binding site between P1 and P9 of p43-58 to either I-Ab or T cell antigen receptor (TCR), we investigated T cell responses to a series of peptides (P2K, P3K, P4K, P5K, P6K, P7K, and P8E) that sequentially substituted charged amino acid residues for the residues at P2 to P8 of p43-58. T cells from C57BL/10 (I-Ab) mice immunized with P4K or P6K did not mount appreciable proliferative responses to the immunogens, but those primed with other peptides (P2K, P3K, P5K, P7K, and P8E) showed substantial responses in an immunogen-specific manner. It was demonstrated by binding studies that P1 and P9 functioned as main anchors and P4 and P6 functioned as secondary anchors to I-Ab. Analyses of Vbeta usage of T cell lines specific for these analogs suggested that P8 interacts with the complementarity-determining region 1 (CDR1)/CDR2 of the TCR beta chain. Furthermore, sequencing of the TCR on T cell hybridomas specific for these analogs indicated that P5 interacts with the CDR3 of the TCR beta chain. The present findings are consistent with the three-dimensional structure of the trimolecular complex that has been reported for TCR/peptide/MHC class I molecules.

Differential scanning calorimetry and CD spectrometry of acclimation temperature-associated types of carp light meromyosin

Differential scanning calorimetry and CD spectrometry were employed to study the thermal unfolding of light meromyosin (LMM) prepared from carp acclimated to different temperatures. The transition temperatures given by the major peaks at pH 8.0 in 0.6 M KCl for LMM from carp acclimated to 10 degrees C were 32.5 and 39.5 degrees C with the calorimetric enthalpies (DeltaHcal) of 269 and 52 kcal/mol, respectively. LMM from carp acclimated to 20 degrees C exhibited three peaks of transition temperatures at 34.5, 40.2, and 46.9 with DeltaHcal of 152, 20, and 10 kcal/mol, respectively. On the other hand, LMM from carp acclimated to 30 degrees C showed two different patterns. The first experiment gave two transition temperatures at 39.2 and 47.3 degrees C with DeltaHcal of 231 and 39 kcal/mol, respectively. The second series of experiments resulted in showing three peaks of 34.4, 39.5, and 47.5 degrees C with DeltaHcal of 117, 123, and 28 kcal/mol, respectively. N-terminal amino acid sequence analysis revealed that LMM at the second series of experiments with the 30 degrees C-acclimated carp contained component(s) predominant in the 20 degrees C-acclimated carp. Thermal unfolding responsible for these transition temperatures was well explained by melting of alpha-helices which could be determined by far-ultraviolet CD spectroscopy. These results clearly demonstrate that the 30 degrees C-acclimated carp contained the most thermostable LMM.

Genomic organization of the mouse adrenocorticotropin receptor

As a step toward understanding the transcriptional regulation of the adrenocorticotropin receptor (ACTH-R) gene, we examined the full length cDNA sequence of the mouse ACTH-R by rapid amplification of cDNA ends, and the organization of the gene. Mouse ACTH-R mRNA consists of 374 bp in the 5'-untranslated region (UTR), 888 bp in the coding sequence, and 445 bp in the 3'-UTR, the 1707 bp being fairly compatible with the 1.8-kb adrenal mRNA detected by Northern analysis. The mouse ACTH-R gene consists of at least four exons; the first three exons encode 5'-UTR and the fourth exon encodes part of 5'-UTR, the entire coding region, and the whole of 3'-UTR. We also defined two mRNA species, one with and one without the 57-bp exon 2, produced by alternative splicing.

Structure and expression of the mouse S10 gene

We previously reported the cloning of a human S10 cDNA which encodes a small GTP-binding protein belonging to the Rab subfamily. Here we describe a mouse S10 cDNA and its genomic structure. Mouse S10 is 92.3% homologous at the nucleotide level and 98.3% identical at the amino acid level compared to human S10. The mouse S10 gene is comprised of two exons and a single intron. Northern blotting of tissue RNAs indicates that the S10 gene is predominantly expressed in brain.

cDNA cloning of myosin heavy chain isoforms from carp fast skeletal muscle and their gene expression associated with temperature acclimation

We have isolated cDNA clones encoding fast skeletal muscle myosin heavy chains of carp acclimated to 10, 20 and 30 degrees C for over 5 weeks. All clones covered at least the full length of L-meromyosin, the C-terminal part of the myosin molecule. Nucleotide sequence analysis on cDNA clones showed three types of 3' untranslated sequences, demonstrating that carp expresses at least three myosin heavy chain isoforms in fast skeletal muscle in an acclimation-temperature-dependent manner. cDNAs were identified which were the predominant types expressed in 10 degrees C- and 30 degrees C-acclimated fish, as well as an intermediate type present at all acclimation temperatures. Northern blot analysis using probes of three kinds of DNA fragments from the 3' untranslated region of carp acclimated to 10, 20 and 30 degrees C further confirmed the presence of acclimation-temperature-specific isoforms. In addition, it was found that mRNA levels of three isoforms were altered in an acclimation-temperature-dependent manner. When the deduced amino acid sequences of three types of carp L-meromyosin were compared with those of homoiotherms, the 30 degrees C-acclimated type was more similar to those of homoiotherms than was the 10 degrees C-acclimated type.

Amplification of a full-length Borna disease virus (BDV) cDNA from total RNA of cells persistently infected with BDV

We have developed a novel reverse transcriptase-polymerase chain reaction (RT-PCR) to amplify the full-length 8.9 kilobase (kbp) cDNA of the Borna disease virus (BDV) RNA genome from the total cellular RNA of MDCK cells persistently infected with BDV (MDCK/BDV). Antigenomic BDV cDNA was reverse transcribed using a 53-mer oligonucleotide primer, corresponding to the 5'-terminus of a putative 3'-leader sequence of the BDV RNA genome, for 2 hr at 42 C followed by 30 min at 55 C. PCR was performed in the presence of this 53-mer antigenomic primer and a 25-mer primer, corresponding to the 3'-terminus of the BDV antigenomic cDNA, by use of an rTth DNA polymerase with proof-reading activity. The amplified full-length BDV cDNA was detected in as little as 20 ng of total cellular RNA of MDCK/BDV. This RT-PCR method should be a useful technique to study the molecular quasispecies of BDV.

A novel missense mutation in the thyroid hormone receptor beta gene in a kindred with resistance to thyroid hormone

Direct sequencing of exon 9 of the thyroid hormone receptor beta (TRbeta) gene in a kindred with resistance to thyroid hormone revealed a substitution of threonine for methionine in codon 313 in one allele resulting from a T to C transition. This is a novel missense mutation that resides in one of the two mutational "hot-spot" regions of the TR beta gene suggesting altered triiodothyronine binding to this mutant receptor.

Sequence variability of Borna disease virus open reading frame II found in human peripheral blood mononuclear cells

A cDNA fragment of the Borna disease virus (BDV) open reading frame II (ORF-II), which encodes a 24-kDa phosphoprotein (p24 [P protein]), was amplified from total RNA of peripheral blood mononuclear cells (PBMC) from three psychiatric inpatients. The amplified cDNA fragments were cloned, sequenced, and analyzed. A total of 15 clones, 5 from each patient, were studied. Intrapatient divergencies of the BDV ORF-II nucleotide sequence were 4.2 to 7.3%, 4.8 to 7.3%, and 2.8 to 7.1% for the three patients, leading to differences of 7.7 to 14.5%, 10.3 to 17.1%, and 6.0 to 16.2%, respectively, in the deduced amino acid sequence for BDV p24. Interpatient divergencies among the 15 clones were 5.9 to 12.7% at the nucleotide level and 12.8 to 28.2% at the amino acid level. Thus, in p24, BDV in human PBMC of the patients undergoes mutation at high rates in vivo. Additionally, we found that the nucleotide sequence of the 15 human BDV ORF-II cDNA clones differed from those of the horse strains V and He/80-1 by 4.2 to 9.3%. However, comparison of the consensus amino acid sequence deduced from the 15 human clones with those of the horse strains revealed no human-specific amino acid residue, suggesting that the BDV infecting humans may be related to that infecting horses.

Production of recombinant hantavirus nucleocapsid protein expressed in silkworm larvae and its use as a diagnostic antigen in detecting antibodies in serum from infected rats

The recombinant nucleocapsid protein (rNP) of Hantaan virus was expressed by a baculovirus vector in silkworm hemolymph and was used as an antigen in western blotting (WB). The rNP is expressed in insoluble form in hemolymph; therefore simple washing of the insoluble fraction with phosphate-buffered saline by low-speed centrifugation allowed preparation of purified antigen for WB. The rNP had strain-specific and hantavirus-common epitopes similar to the authentic NP antigen of hantavirus and was stable after transfer to membrane. For detection of antibody in serially obtained sera from experimentally infected rats, WB enabled detection of IgM antibodies 3 days after infection, which was at least 2 days earlier than detection by the indirect immunofluorescent antibody test (IFA). Thus WB had a higher sensitivity than the IFA for detection of hantavirus antibody in the serum of experimentally infected rats. The WB-determined IgG antibody titer was about 10 times higher than that determined by the IFA. No background staining was observed by WB even at a 1:10 dilution of serum. The selected rat sera with strong background staining or confusing staining patterns by IFA, but not focus reduction neutralization test titers, could be interpreted as test-negative because they did not have a specific reaction to virus antigen by WB. Thus the specificity of WB was higher than that of the IFA. Moreover, WB can distinguish specific from nonspecific reactions by the detection of the specific antigen on the WB membrane. Therefore the IFA or enzyme-linked immunosorbent assay followed by WB is recommended for serologic confirmation of hantavirus infection.

Naturally occurring accessory gene mutations lead to persistent human immunodeficiency virus type 1 infection of CD4-positive T cells

Proviral DNA from cells surviving severe but transient cytopathic effects, mediated by infection with recombinant human immunodeficiency virus type 1 (HIV-1) carrying a single gene mutation at vif, vpr, or vpu, was characterized by use of HIV-1-specific primer pairs in a two-step PCR. Deletion mutations were detected in a region that spanned the vif and vpr open reading frames. Cloning and sequencing of the amplified DNA from this region revealed frequent large deletions in a limited number of nucleotide positions. Analyses of the deletions suggested that (i) genetic recombination, (ii) template-primer slippage, and (iii) misalignment of the growing point during reverse transcription of the HIV-1 genome might be the mechanisms that generated the mutations. Apart from the large deletions, smaller deletions that gave frameshift mutations in vif and/or vpr prevailed. In addition, cells infected with a triple mutant defective in vif, vpr, and vpu did not show any cytopathic effect. Thus, mutations generating multiple accessory gene defects during HIV-1 replication correlate with viral persistence and loss of cytopathogenicity.

Prevalence of Borna disease virus RNA in peripheral blood mononuclear cells from blood donors

The presence of Borna disease virus (BDV) in peripheral blood mononuclear cells (PBMC) of 100 blood donors from Sapporo and 72 blood donors from Tokyo was examined using nested reverse transcriptase/polymerase chain reaction amplification with specific-primers for BDV p24. Anti-BDV p24 antibodies in the plasma of the 100 blood donors from Sapporo also were studied by enzyme-linked immunosorbent assay and by Western blot. BDV RNA was detected in 3 (4.2%) of the 72 PBMC samples from Tokyo, and in 5 (5%) of the 100 PBMC samples from Sapporo. In contrast, anti-p24 antibodies were found in only 1 (1%) of the donors from Sapporo. These results suggest that BDV infection in humans may be more widespread than previously thought.

Demonstration of human Borna disease virus RNA in human peripheral blood mononuclear cells

BDV naturally infects horses and sheep, and causes sporadic neurological disease. Serological evidence suggests an association of BDV, or a related virus, with specific psychiatric diseases in humans. Here, by using a nested RT-PCR technique, we demonstrate that human BDV RNA is present in the PBMC of psychiatric patients. In an examination of a total of 60 patients from 5 wards of a hospital in Japan, the detection rate differed within each ward, ranging from 8% to > 50% (37% on the average). Of particular note was the finding that the human derived BDV sequences, which included deleted forms in about 23% of the positive samples, were slightly different from those derived from horse BDV. These results suggest urgent consideration of the measures to be taken to cope with the effects of blood transfusion. In addition, the detection of a high level of BDV in the PBMC of patients will help our understanding of the pathogenesis in the disease.

Cloning of a mouse adrenocorticotropin receptor-encoding gene

A genomic DNA encoding a mouse adrenocorticotropin (ACTH) receptor was isolated. The predicted 296-amino-acid sequence showed 88.9 and 78.7% identities to the human and bovine homologues, respectively.

Superinfection of a defective human immunodeficiency virus type 1 provirus-carrying T cell clone with vif or vpu mutants gives cytopathic virus particles by homologous recombination

The partially CD4-expressing T cell clone, Vpr-1, which carries a latent vpr-defective HIV-1 genome and expresses HIV-1 Nef protein only, was permissive to superinfection by HIV-1. Superinfection of Vpr-1 with vif- or vpu-defective mutants, which were noncytopathic, reactivated the vpr-defective virus and led to homologous recombination and cytopathogenesis. The data provide an experimental model for homologous recombination being an important mechanism whereby HIV-1 acquires genetic heterogeneity, and when occurring among defective virus in vivo bestows novel biological activities and virulence.

An upstream NF-Y-binding site is required for transcriptional activation from the hst promoter in F9 embryonal carcinoma cells

Expression of hst (k-FGF, FGF-4), a member of the fibroblast growth factor gene family, is restricted to early stages of developing embryos and to embryonal carcinoma cells. In F9, which is a prototype of embryonal carcinoma cells expressing hst, the expression of hst gene is positively regulated by a downstream octamer motif that functions as an enhancer. We have investigated, by chloramphenicol acetyltransferase (CAT) reporter fusion gene analysis in F9, the cis-acting regulatory element within the hst promoter region that interacts with this enhancer. Electrophoretic mobility shift assay and methylation interference analysis showed that the hst promoter contains, in a segment termed Y, the sequence 5'-CTGATTGGCA-3', which closely resembles the consensus binding motif for the CCAAT-binding factor NF-Y. Deletions or mutations in this element substantially reduced expression of hst-CAT constructs. The nuclear factor binding to the Y segment of the hst promoter was indistinguishable from NF-Y, as inferred from interactions with specific anti-NF-Y monoclonal and polyclonal antibodies. We conclude that the expression of the hst gene in F9 is positively regulated by the coordinated interaction between an NF-Y-binding site and an octamer motif.

Chronic myeloid leukemia presenting ALL-type BCR/ABL transcript

We investigated the breakpoints of the bcr gene in 46 Ph1-positive CML cases by Southern blot analysis of bcr rearrangement, and in 17 CML cases by a combination of Southern blot analysis and RT-PCR. By Southern blot, the breakpoint was not identified on M-bcr in three CML cases, of which one case showed the P210-type bcr/abl transcript and two cases showed the ALL-type (P190-type) bcr/abl transcript with or without P210 transcript. Later two cases showed unique hematological profiles such as thrombocytosis, mild myelofibrosis, and relative resistance to alkylating agents. Therefore, the present study suggests that expression of the P190-type transcript may affect clinical and hematological findings in CML.

Regulatory sequences required for hst-1 expression in embryonal carcinoma cells

The hst-1 gene, which is implicated in mammalian embryonic development and morphological transformation of NIH3T3 cells, is expressed in undifferentiated F9 cells, but not in differentiated F9 and other well-differentiated cells, such as PYS-2, NIH3T3 and HeLa cells. An octamer element present in the 3' untranslated region acts as an enhancer. Although Oct3 is down-regulated when F9 cells are differentiated, transient expression of Oct3 did not enhance the hst-1 promoter activity in HeLa, NIH3T3 or PYS-2 cells. Thus, the role of Oct3 on hst-1 expression remains elusive, and an additional transcription factor which interacts may regulate hst-1 transcription in association with Oct1, Oct3 or both.

Molecular cloning of a cDNA encoding a novel small GTP-binding protein

A cDNA encoding a small GTP-binding protein, S10, was cloned from Jurkat cells. The deduced amino acid sequence of S10 had the structural features characteristic to this family of proteins with highest homology to rab subfamily. Northern blot analysis revealed that this gene is expressed only in lymphoid cell lines and a histiocytic leukemia, U937. Hence, it should have a specialized function in cells derived from the hematopoietic stem cell.

Heterogeneity of HLA-G genes identified by polymerase chain reaction/single strand conformational polymorphism (PCR/SSCP)

A genomic HLA-G clone named 7.0E was isolated from a Japanese placenta. The deduced amino acid sequence of the 7.0E was identical to two HLA-G genomic clones and two cDNA clones previously described. The DNA sequences of alpha 1 and alpha 2 domains of the HLA-G gene from 5 cell lines also encoded the same amino acids. However, a 14 bp insertion, ATTTGTTCATGCCT, was present in the 3' untranslated region of 7.0E compared with the originally described HLA-G clone (HLA 6.0). Polymerase chain reaction (PCR)/single strand conformational polymorphism (SSCP) analysis of exon 8 allowed the HLA-G gene to be classified into two alternative types, G6.0 and 7.0 E, those correlated to the absence or the presence of the 14 bp stretch. Each group had minor sequence variant(s), and the alleles of the 7.0E-type were more heterogeneous than those of the G6.0-type. The 14 bp deletion is present only in the G6.0-type of HLA-G alleles among HLA class I genes. Thus it was suggested that G6.0 alleles were generated after diversification of the HLA-G.

Transcriptional repression and differential splicing of Fas mRNA by early transposon (ETn) insertion in autoimmune lpr mice

Lpr (lymphoproliferation) is a recessive trait caused by a mutation in the Fas gene which reduces the Fas transcript substantially. When reverse transcription polymerase chain reaction (RT-PCR) was performed using pairs of primers surrounding a particular portion of Fas mRNA, wild-type and approximately 180 base pair (bp) longer PCR products were consistently generated from lpr thymocytes. The latter contained an insertion of 183 nucleotides which was 98.9% homologous to early transposon (ETn) which was found in an immunoglobulin switch region of murine plasmacytoma, P3.26Bu4. These data clearly indicate that ETn insertion into the Fas gene intron causes transcriptional repression. However, this defect may be leaky due to the production of intact Fas mRNA by splicing out ETn-containing intron from primary Fas transcripts. The inserted 183 bp fragment has a potential to code in-frame 61 amino acids, so that the mutant Fas antigen may also be produced. Low level expression of wild-type and mutant Fas antigens may be relevant to the variable phenotype in lpr mice.

Cell cycle dependent gene expressions and activities of protein phosphatases PP1 and PP2A in mouse NIH3T3 fibroblasts

We determined the mRNA levels and the activities in nuclear and non-nuclear fractions of protein phosphatase type 1 (PP1) and type 2A (PP2A) through the cell cycle in synchronized mouse NIH3T3 fibroblasts. The mRNA level for PP1 alpha was gradually elevated in late G1 phase, began to decrease in M phase, and reached the control level with entering into the next G1 phase. The mRNA level for PP2A was rapidly increased in early G1 phase, kept at the high level, and decreased after S phase. In nuclear fractions of cells, spontaneous activities of both PP1 and PP2A were gradually increased until M phase and rapidly decreased with entering the next G1 phase, while in non-nuclear fraction such dramatic alterations were not observed. Potential activities of PP1 in both fractions revealed by Co(2+)-trypsin treatment showed an oscillaion patterns similar to those of the spontaneous activities. These results strongly suggest that cell cycle dependent gene expressions and activities of PP1 and PP2A play roles in DNA synthesis and mitosis during the cell cycle.

Expression of myeloid cell phenotypes by a novel adult T-cell leukemia/lymphoma cell line

BACKGROUND

Human T-cell leukemia virus type 1 (HTLV-1) can infect a number of cells of different lineages in vitro, yet the immunophenotypes of most adult T-cell leukemia/lymphomas (ATLs) are restricted to CD4+. The apparent discrepancy between these findings is still largely unknown.

PURPOSE

We report on a unique case of ATL in which the leukemia cells were positive for both T-cell and myeloid cell antigens. To characterize these cells, we isolated cell lines from this patient with ATL.

METHODS

The fresh leukemia cells were cultured without the addition of interleukin-2. Cell cloning was carried out by limiting dilution.

RESULTS

A cell line (MU) and its clonal sublines were established. MU cells showed the same chromosomal abnormalities and T-cell receptor beta-chain gene rearrangement pattern as those of fresh leukemia cells. MU cells were exclusively positive for a myeloid cell marker (CD13) but not for T-cell markers, despite the presence of T-cell receptor gene rearrangement.

CONCLUSION

The established ATL cell line showed both T-cell and myeloid cell characteristics, which seems to be the first evidence for the close association of ATL cells with both lymphoid and myeloid features. The cell line may provide a new insight for the targets of HTLV-1 infection and transformation in vivo.

Cells surviving infection by human immunodeficiency virus type 1: vif or vpu mutants produce non-infectious or markedly less cytopathic viruses

Under conditions in which a clonal cell line (M10) isolated from a human T cell lymphotrophic virus type I-transformed MT-4 cell line was completely killed by infection with wild-type human immunodeficiency virus type 1 (HIV-1), equivalent M10 cells survived infection with HIV-1 vif, vpr or vpu mutant virus after transient cytopathic effects. Several cell clones, which were isolated from the proliferating M10 cells after infection with vif and vpu mutant viruses (M10/vif- and M10/vpu-), had heterogeneous HIV-1 phenotypes in terms of HIV-1 antigen expression, their syncytium forming capacity, reverse transcriptase activity and the infectivity of HIV-1 particles produced. When the replication kinetics of the HIV-1 particles produced were assayed in M10 cells, the clones could be classified into three types, i.e. type I producing non-infectious HIV-1, type II producing infectious HIV-1 with low replicative ability and type III producing infectious HIV-1 with a replicative ability similar to that of wild-type HIV-1. HIV-1 major viral cell proteins and virus particle fractions were almost typical in types II and III but not in type I. Electron microscopic examination of particles released by I, II and III clones revealed rare defective, predominantly defective and essentially normal virions, respectively. Northern and Southern blot analyses revealed no apparent deletion in the proviral DNA and mRNA prepared from these clones, except in the case of type I and II clones isolated from M10/vpu- which contained large deletions in the mRNAs for gag and gag-pol proteins. Thus, M10 cells surviving infection with HIV-1 vif or vpu mutants are heterogeneous, persistently expressing HIV-1 antigens and producing non-infectious or less cytopathic virus.

Regulation of human hst expression by an enhancer element residing in the third exon

The hst gene is exclusively expressed in undifferentiated embryonal carcinoma cell lines and at a limited stage of embryonal development. Two DNase I-hypersensitive sites were mapped in the 3' region (approximately 3.5 and 4.5 kb downstream of the translational initiation site) of the human hst gene, irrespective of the presence or absence of hst mRNA in the cells. A DNA fragment containing one of these DNase I-hypersensitive sites (at around 3.5 kb relative to the translational initiation site) showed enhancer activity when tested by chloramphenicol acetyltransferase (CAT) assay. These results strongly suggest that an enhancer element(s) exists in the third exon of the hst and that the expression of the hst may be regulated by the presence or absence of a putative protein factor(s) which binds to the enhancer.

Molecular cloning and sequence analysis of cDNA and genomic DNA for the human cone transducin alpha subunit

A novel GTP binding protein (G protein) alpha subunit cDNA was isolated from a T cell leukemia cell line, Jurkat, utilizing polymerase chain reaction (PCR). The predicted amino acid sequence of this G protein alpha subunit showed the highest identity (96.6%) to bovine cone cell-specific transducin (Tc alpha). The organization of the coding region of this G protein alpha subunit gene was composed of 8 exons and 7 introns. Northern hybridization revealed the presence of this G protein message in a retinoblastoma cell line, Y79. In Jurkat, however, the message was detectable only by reverse transcription/PCR. Taken together, this novel G protein alpha subunit must be human Tc.

Mapping and transcriptional properties of RT1 class II region genes

The class II region of major histocompatibility complex of the rat. Rattus norvegicus (RT1) consists of RT1.B, RT1.D, and RT1.H subregions. The gene order around the H subregion was determined as RT1.A--H beta-H alpha--B by RFLP analysis of naturally occurring intra-RT1 recombinant rats with HLA DP probes. A unique recombinant strain, LEJ, was found to have its recombinational site between H beta and H alpha (RT1.AuH beta uH alpha bBbDb). Northern analysis of class II mRNAs showed that transcripts of RT1.D alpha, RT1.D beta, and RT1.B alpha shared identical sizes among various strains of rats, but RT1.B beta mRNA showed allele-specific size heterogeneities. Northern hybridization with HLA DP alpha probes detected possible RT1.H alpha transcripts. On the other hand, no clear signal of H beta was observed. BDIX whose RT1.B products had not been identified was found to transcribe B alpha and B beta mRNAs.

bcr rearrangement and C-abl gene expression in Ph1-positive hybrid acute leukemia with simultaneous proliferation of lymphoid and myeloid blasts

bcr gene rearrangement and c-abl gene expression were analyzed in a patient with Philadelphia chromosome (Ph1)-positive hybrid acute leukemia with simultaneous proliferation of lymphoid and myeloid blasts. These data were compared with those from a patient with chronic myelogenous leukemia (CML) in mixed crisis. The leukemic cells of both patients showed immuno-phenotypic profiles such as non-T, non-B common ALL with some MPO-positive leukemic cells and rearranged JH genes. On analysis of molecular events associated with the Ph1 chromosome, the leukemic cells of a patient with CML in mixed crisis showed bcr rearrangement and an 8.5-kb bcr-abl chimeric mRNA, but those of a patient with Ph1-positive hybrid acute leukemia showed no 8.5-kb bcr-abl mRNA, as previously reported in a number of Ph1-positive acute lymphoblastic leukemia (ALL) cases. These results revealed that the molecular event found in Ph1-positive ALL is not only restricted to lymphoid lineage but may play an important role in the proliferation of the myeloid lineage.