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Biomedical subjects

F Harada

Publications and source records attributed to F Harada.

At least 37 records · Page 2Linked to original sources
PubMed1986

Molecular cloning and in vitro transcription of rat 4.5S RNAH genes.

4.5S RNAH (4.5S RNA associated with poly A containing RNA) has extensive homology to major interspersed repeat B1 in rodent genomes. We developed a new cloning technique for screening genomic library that eliminates the signal produced by repeated sequences or pseudogenes and applied it to cloning of 4.5S RNAH genes. Six phage clones (2, 3, 6, 9, 10 and 15) which hybridize with 4.5S RNAH were isolated from a rat gene library by this method. The restriction fragments containing the 4.5S RNAH locus were subcloned into plasmids and sequenced. Clones 2, 3, 9 and 15 contained one to five base substitutions in the coding region for 4.5S RNAH and were probably pseudogenes. In clone 2, the 4.5S RNAH locus was linked directly with the identifier sequence. Clone 6 contained three copies of the 4.5S RNAH gene (6a, b and c) which were clustered in the same direction within 455 base pairs. 6b was linked directly with 6c and ubiquitous repetitive DNA sequences B2 were inserted immediately after 6a and 6c. These three sequences as well as the sequence in clone 10 were colinear with rat 4.5S RNAH. In an in vitro transcription system, only clone 10 gave intact 4.5S RNAH.

Animals↗
PubMed1986

Cloning and characterization of rat 4.5S RNAI genes.

Genomic clones containing genes for 4.5S RNAI, which is an abundant small nuclear RNA found in rodent cells, were obtained from a rat genomic library. Thirty-four clones that formed RNase A resistant hybrids with 3'-end-labeled 4.5S RNAI were isolated, and seven of them (clones lambda I39, lambda I41, lambda I42, lambda I51, lambda I106, lambda I123 and lambda I154) were characterized by sequencing and in vitro transcription. Clones lambda I41 and lambda I123 carry one and two genes, respectively, with identical sequences to that of 4.5S RNAI and are actively transcribed in vitro. However, the other five clones contain sequences that seem to be pseudogenes for 4.5S RNAI, since they have nucleotide substitutions or deletions in the sequence corresponding to 4.5S RNAI or are not transcribed. Four clones (lambda I39, lambda I42, lambda I106 and lambda I154) were found to have 13-18 nucleotide-long direct repeats flanking the 4.5S RNAI sequences. The genomic organization of the genes and their related sequences is discussed.

Animals↗
PubMed1986

Occurrence of two beta-tubulin isoforms with different polymerizing abilities in L5178Y cells.

Mouse lymphoma L5178Y cells express at least two isoforms of beta-tubulin, designated M beta I and M beta II, as revealed by isoelectrofocusing, whereas two independently isolated normal T-cell clones, 3D10 and K23, express only M beta I. M beta II-tubulin is more acidic (pI, 5.10) than M beta I-tubulin (pI, 5.15). L5178Y cells were disrupted under the microtubule-stabilizing conditions, followed by centrifugation to separate fractions containing polymerized and unpolymerized tubulin. We found that a proportion of M beta II to total beta-tubulins is larger in the fraction containing unpolymerized tubulin than in that containing polymerized tubulin. In addition, when tubulin was purified from extracts of L5178Y cells by repeated cycles of polymerization-depolymerization, the M beta II-tubulin isoform was gradually lost during the successive purification steps. The low recovery of M beta II-tubulin was observed, irrespective of the presence or absence of MAPs, and even in the presence of an excess amount of essentially polymerizable porcine brain tubulin. These results indicate that M beta II-tubulin is less able to polymerize than is M beta I-tubulin, both in vivo and in vitro.

Animals↗
PubMed1986

Two mammalian heat shock proteins, HSP90 and HSP100, are actin-binding proteins.

Two high molecular weight heat shock proteins, HSP90 (Mr, 90,000) and HSP100 (Mr, 100,000), were separately purified from extracts of cultured cells of a mouse lymphoma cell line, L5178Y. Both of the HSPs exist in homodimeric form under physiological conditions. Their physicochemical properties are quite similar to each other. Each of the purified HSPs was shown to coprecipitate with rabbit skeletal muscle actin under actin-polymerizing conditions. Both HSP90 and HSP100 increased the low-shear viscosity of filamentous actin solutions in a dose-dependent manner, which suggests that these HSPs cross-link actin filaments. Although some molecular properties and the effects described above on actin solution of HSP90 and HSP100 resemble those of alpha-actinin, the HSPs were distinguished from alpha-actinin by various means, including visualization of molecular shapes by electron microscopy with the aid of the low-angle rotary shadowing technique. Immunofluorescence staining by specific antisera against HSP90 revealed that HSP90 was localized in ruffling membranes in addition to the cytoplasmic space.

Actins↗
PubMed1985

New U1 RNA species found in Friend SFFV (spleen focus forming virus)-transformed mouse cells.

The U1 RNA species in 10 mouse cell lines were examined by two-dimensional polyacrylamide gel electrophoresis. Seven cell lines that were not infected by Friend spleen focus forming virus gave only one (I) or two (I and II) U1 RNA-containing spots. However, two Friend cell lines (FVTCT and Friend 745a cells) gave three spots (I, II, and III) and another Friend cell line, K-1 cells, gave four spots (I, II, III, and IV). As a result of further separation and fingerprinting analysis of each spot, FVTCT and Friend 745a cells were found to contain U1a-1, U1b-1, -2, and -6 RNAs whereas K-1 cells were found to contain several U1 RNAs, which we call U1a-1 and -2, U1b-4, -5, and -6 RNAs. We determined the sequences of these seven U1 RNAs and found that mouse U1 RNAs had two basic sequences (U1a and -b). The nucleotide sequence of U1a-1 RNA was identical to that of rat U1a RNA, while U1a-2 RNA was one base different from U1a-1 RNA. Relative to U1a-1 RNA all of the U1b RNAs had five base substitutions and one additional base and were under-methylated in the center. U1b-6 RNA contained two base substitutions and one base addition in the 3'-terminal portion of U1b-1 RNA. U1b-2, -4, and -5 RNAs, which were observed only in Friend cells, each had an additional base substitution in the 5'-half of U1b-1 RNA.

Animals↗
PubMed1985

Structure-activity relationship of thirty-nine cytochalasans observed in the effects on cellular structures and cellular events and on actin polymerization in vitro.

The effects of twenty-three natural cytochalasans and sixteen synthetic derivatives on actin-distribution and alteration in morphology of C3H-2K cells, inhibition of lymphocyte capping, and inhibition of actin filament elongation were compared. The effects on cellular level and the in vitro effects showed positive correlation and the structure-activity relationship observed is discussed.

Actins↗
PubMed1984

Stable tRNA precursors in HeLa cells.

Two tRNA precursors were isolated from 32P-labeled or unlabeled HeLa cells by two dimensional polyacrylamide gel electrophoresis, and were sequenced. These were the precursors of tRNAMet and tRNALeu, and both contained four extra nucleotides including 5'-triphosphates at their 5'-end and nine extra nucleotides including oligo U at their 3'-end. These RNAs are the first naturally occurring tRNA precursors from higher eukaryotes whose sequences have been determined. In these molecules, several modified nucleosides such as m2G, t6A and ac4C in mature tRNAs were undermodified. Two additional hydrogen bonds were formed in the clover leaf structures of these tRNA precursors. These extra hydrogen bonds may be responsible for the stabilities of these tRNA precursors.

Base Sequence↗
PubMed1984

Nucleotide sequence of nuclear 5.4 S RNA of mouse cells.

The nucleotide sequence of nuclear 5.4 S RNA, a new species of small nuclear RNA (snRNA) of mouse cells, was determined. The 5.4 S RNA consists of 138 nucleotide residues containing 1 mol each of 2,2,7- trimethylguanosine (m3(2,2,7) G), 2'-O-methyladenosine (Am), 2'-O-methyluridine (Um) and pseudouridine as modified nucleosides. This RNA has a cap structure, m3(2,2,7) ++GpppAm -, at its 5'-terminus and sequences complementary to the terminal consensus sequences of introns. The sequence complementary to the 5'-splice junction, A-U-C-C-psi-U-A-C-C-U-G, is very similar to the 5'-terminal sequence of U1 RNA.

Animals↗
PubMed1984

Isolation of a novel antibody, which precipitates ribonucleoprotein complex containing threonine tRNA from a patient with polymyositis.

We have isolated and characterized a novel antibody from a patient with polymyositis, which precipitates threonine tRNA and an unknown small RNA molecule from 32P-labeled HeLa extract. Fingerprint analysis showed that the human threonine tRNA precipitated was nearly identical to the murine tRNA described by Harada [(1978) Seikagaku 50, 397-411]. Nucleotide analysis suggested that the other small RNA molecule might be transfer RNA. Since phenol extraction resulted in the loss of immunoprecipitability, the protein portion was presumed to be involved in the recognition of the antigen. Immunofluorescence staining of HeLa cells with the antibody clearly demonstrated that the antigen was located predominantly in the cytoplasm.

Autoantibodies↗
PubMed1984

Characterization of a Rous sarcoma virus mutant defective in packaging its own genomic RNA: biochemical properties of mutant TK15 and mutant-induced transformants.

The accompanying paper (S. Kawai and T. Koyama , J. Virol. 51:147-153, 1984) describes the isolation and biological properties of a mutant, TK15 , derived from a Rous sarcoma virus mutant, tsNY68 . The cis-acting defect of the mutant is analyzed biochemically in this paper. TK15 virions released from virus-producing 15c (+) cells were deficient in viral genomic 39S RNA, although comparable amounts of viral RNAs were transcribed in 15c (+) and tsNY68 -infected cells. Analysis of provirus DNA occurring in 15c (+) cells suggested that the mutant genome had a deletion of ca. 250 bases near the 5' end of the genome somewhere between the primer binding site and the 5' end of the gag-coding region. These findings indicate that at least part of the sequence lost in the TK15 genome is indispensable for packaging viral genomic RNA into virions. TK15 induces nonvirus -producing 15c (-) transformants at high frequency. Southern blot analysis of DNAs from those 15c (-) clone cells revealed that TK15 -derived proviruses contained various extents of internal deletions. Many 15c (-) clones had a provirus carrying only the src gene with long terminal repeat sequences at both ends. The mechanism for the segregation of 15c (-) cells is discussed.

Avian Sarcoma Viruses↗
PubMed1983

Chemical modification of cytosine residues of U6 snRNA with hydrogen sulfide (nucleosides and nucleotides. Part 49 [1]).

Sulfhydrolysis of cytosine residues to 4-thiouracil residues in mouse U6 snRNA was carried out to examine the secondary structure of U6 snRNA. The cytosine residues at positions 6, 42 and 68 were modified significantly, and at positions 11, 19 (or/and 25), 61 and 66 in moderate extent. Based on the result, the plausible secondary structure of U6 snRNA is discussed.

Animals↗