Biomedical subjects

Michiteru Yoshida

Publications and source records attributed to Michiteru Yoshida.

8 recordsLinked to original sources

PubMed2006

Reaction on D-glucal by an inverting phosphorylase to synthesize derivatives of 2-deoxy-beta-D-arabino-hexopyranosyl-(1-->4)-D-glucose (2II-deoxycellobiose).

Four derivatives of 2(II)-deoxycellobiose were synthesized from d-glucal and acceptor sugars (d-glucose, d-xylose, d-mannose, and 2-deoxy-d-arabino-hexose) using a cellobiose phosphorylase from Cellvibrio gilvus. The enzyme was found to be an effective catalyst to synthesize the beta-(1-->4) linkage of 2-deoxy-d-arabino-hexopyranoside. The acceptor specificity for the d-glucal reaction was identical to that for the alpha-d-glucose 1-phosphate reaction, but the activity of d-glucal was approximately 500 times less than that of alpha-d-glucose 1-phosphate, using 10mM substrates.

Calcium Gluconate↗

PubMed2004

Acidic C-tail of HMGB1 is required for its target binding to nucleosome linker DNA and transcription stimulation.

HMGB1, a nonhistone chromosomal protein in higher eukaryotic nuclei, consists of two DNA binding motifs called HMG boxes and an acidic C-tail comprising a continuous array of 30 acidic amino acid residues. In the preceding study, we showed that the acidic C-tail of HMGB1 is required for transcription stimulation accompanied by chromatin decondensation in cultured cells. However, details of the involvement of the acidic C-tail in transcription stimulation were not clear. To clarify the mechanism of transcription stimulation by the acidic C-tail, we assessed the effect of the acidic C-tail on the transcription stimulation and nucleosome binding. Transcription stimulation assays using acidic C-tail deletion mutants showed that the five amino acid residues at the C-terminal end of HMGB1, a DDDDE sequence, are essential for the stimulation. The DDDDE sequence was also required for the preferential binding of HMGB1 to nucleosome linker DNA, which is a cognate HMGB1 binding site in chromatin. Cross-linking and far-Western experiments demonstrated that the DDDDE sequence interacts with the core histone H3 N-tail. These results strongly suggest that the interaction between the DDDDE sequence of HMGB1 and the H3 N-tail is a key factor for the transcription stimulation by HMGB1 as well as the preferential binding of HMGB1 to chromatin.

Animals↗

PubMed2004

ATP-dependent chromatin structural modulation by multiprotein complex including HMGB1.

High mobility group box protein 1, HMGB1, is a major nonhistone chromatin component in higher eukaryotic cells. HMGB1 is thought to be involved in the processes of global nuclear events such as transcription, recombination and repair, but the mechanism of these processes is unclear. Here, we show a concrete example of chromatin structural modulation by HMGB1 in HeLa S3 cells. A co-immunopurification experiment with Flag-tagged HMGB1 revealed that a portion of HMGB1 in HeLa S3 cells is included in a large-molecular-weight multiprotein complex. The multiprotein complex including HMGB1 showed ATP hydrolysis and ATP-dependent chromatin structural modulation activities that increased the susceptibility of chromatin to MNase digestion, while HMGB1 alone had no such activity. Thus, HMGB1 in the multiprotein complex is critical for expressing the chromatin structural modulation activity. These results suggest that HMGB1 is involved in chromatin structural modulation in global nuclear events through its interaction with a multiprotein complex in mammalian cells.

Adenosine Triphosphate↗

PubMed2004

Conformational difference in HMGB1 proteins of human neutrophils and lymphocytes revealed by epitope mapping of a monoclonal antibody.

HMGB1 and HMGB2 are abundant nonhistone chromosomal proteins in eukaryotic organisms. Their respective primary sequences are highly conserved. Our previous studies showed that these proteins are novel autoantigens of anti-neutrophil cytoplasmic antibodies in sera from patients with ulcerative colitis (UC), rheumatic disease and autoimmune hepatitis (AIH). In the present paper, we showed that anti-HMGB1 and HMGB2 antibodies in sera of patients with UC do not recognize HMGB1 in neutrophils while they recognize the protein in lymphocytes. Anti-HMGB2 monoclonal antibody FBH7, recognizing HMGB1 in lymphocytes, showed a similar profile to the antibodies in the patients' sera. In order to elucidate the difference in immunoreactivity to HMGB1 between neutrophils and lymphocytes, we mapped the epitope for FBH7 by means of several methods. The results showed that FBH7 recognizes the intact conformation composed of 52-56 residues of HMGB1 in lymphocytes. This suggested that HMGB1 in neutrophils is conformationally changed in the epitope or the peripheral structure of the epitope from the protein in lymphocytes. The apparent conformational change of HMGB1 between neutrophils and lymphocytes will be important for understanding the functional difference of HMGB1 in these cells.

Amino Acid Sequence↗

PubMed2002

Involvement of HMGB1 and HMGB2 proteins in exogenous DNA integration reaction into the genome of HeLa S3 cells.

High mobility group 1 and 2 proteins (HMGB1 and HMGB2) are abundant chromosomal proteins in eukaryotic cells. We examined the involvement of HMGB1 and HMGB2 in nonhomologous illegitimate recombination. The HMGB1 or HMGB2 expression plasmid, carrying the neo(r) gene as a selection marker, was introduced into HeLa S3 cells to obtain stably-transfected cells. The number of G418-resistant colonies was about 10 times the number of colonies of control cells transfected with plasmids not carrying the HMGB genes. The copy number of the stably-integrated neo(r) gene was higher in the cells transfected with the HMGB expression plasmids than in control cells. The exogenous DNA integration was suggested to have occurred by nonhomologous illegitimate recombination. On the contrary, the introduction of the HMGB antisense RNA expression plasmid with a reporter plasmid carrying the neo(r) gene into HeLa S3 cells decreased the number of G418-resistant colonies. These results indicate that HMGB1 and HMGB2 each have a novel function as stimulators of stable integration of plasmid DNA into the host genome and that they may be important for the process of spontaneous DNA integration in living cells.

Anti-Bacterial Agents↗

PubMed2002

Characterization of mineral deposits formed in cultures of a hamster tartrate-resistant acid phosphatase (TRAP) and alkaline phosphatase (ALP) double-positive cell line (CCP).

We have established tartrate-resistant acid phosphatase (TRAP) and alkaline phosphatase (ALP) double-positive cell lines (CCP-2, CCP-7, CCP-8) from hamster bone marrow. Accumulation of mineral deposits was observed on the dishes when the clones were cultured in McCoy's 5A medium supplemented with 20% fetal calf serum. The materials were dissolved in 0.05 N HCl, and proteins found in the acid extracts were identified by N-terminal amino acid sequencing. The major components were bovine fetuin and prothrombin precursor. In addition, several cell-derived proteins, such as high mobility group 1 protein (HMG1), secretory leukocyte protease inhibitor (SLPI) and EPV20, a 2.0-kDa milk glycoprotein, were identified. HMG1 was detected, by immunostaining, on the cell surface of all the CCP clones. Metabolically labeled cellular sphingomyelin, sialyllactosylceramide, and proteoglycans were also found in the mineral deposits. Reverse transcription/polymerase chain reaction of CCP-2 mRNA revealed that the cells synthesized alkaline phosphatase, bone sialo protein, and osteonectin, but not matrix Gla protein, osteopontin, and type I collagen. CCP-2 cells formed tumors when injected subcutaneously into nude mice. In the tumor tissue, Alizarin-red-positive nodules surrounded by TRAP- and ALP-positive cells were observed, indicating CCP-2 cells can also induce calcification in vivo.

3T3 Cells↗

PubMed2002

Nucleosome linker proteins HMGB1 and histone H1 differentially enhance DNA ligation reactions.

We previously reported that HMGB1, which originally binds to chromatin in a manner competitive with linker histone H1 to modulate chromatin structure, enhances both intra-molecular and inter-molecular ligations. In this paper, we found that histone H1 differentially enhances ligation reaction of DNA double-strand breaks (DSB). Histone H1 stimulated exclusively inter-molecular ligation reaction of DSB with DNA ligase IIIbeta and IV, whereas HMGB1 enhanced mainly intra-molecular ligation reaction. Electron microscopy of direct DNA-protein interaction without chemical cross-linking visualized that HMGB1 bends and loops linear DNA to form compact DNA structure and that histone H1 is capable of assembling DNA in tandem arrangement with occasional branches. These results suggest that differences in the enhancement of DNA ligation reaction are due to those in alteration of DNA configuration induced by these two linker proteins. HMGB1 and histone H1 may function in non-homologous end-joining of DSB repair and V(D)J recombination in different manners.

DNA↗

PubMed2002

Distorted DNA structures induced by HMGB2 possess a high affinity for HMGB2.

HMGB2 (HMG2) protein binds with DNA duplex in a sequence-nonspecific manner, then bends and unwinds the DNA. In DNA cyclization analyses for the bending activity of HMGB2, two unidentified bands, denoted alpha and beta, were observed in addition to monomer circular DNA (1C) on the gel. Re-electrophoresis and proteinase K digestion revealed that alpha and beta are complexes of circularized probe DNA (seeming 1C) with HMGB2 (K(d) approximately 10(-10) M). The DNA components of alpha and beta (alpha- and beta-DNA) showed higher affinities to HMGB2 than did the linear probe DNA (K(d) approximately 10(-7) M). The DNAs have distorted structures containing partial single-stranded regions. Nicked circular molecules presumably due to severe DNA distortion by HMGB2 were observed in alpha- and beta-DNA, in addition to closed circular double-stranded molecules. The alpha and beta bands were not formed in the presence of sole DNA binding regions which are necessary for DNA bending, indicating that the acidic C-tail in the HMGB2 molecule is necessary for inducing the peculiar distorted structures of higher affinity to HMGB2. HMGB2 binds with linker DNA and/or the entry and exit of nucleosomes fixed at both ends likewise mini-circles similar to alpha-DNA and beta-DNA. Thus, the distorted structures present in alpha-DNA and beta-DNA should be important in considering the functional mechanisms in which HMGB2 participates.

Animals↗