Biomedical subjects

Youichi Suzuki

Publications and source records attributed to Youichi Suzuki.

8 recordsLinked to original sources

PubMed2025

Characterization of the Kaposi's sarcoma-associated herpesvirus terminase complex component ORF29.

Kaposi's sarcoma-associated herpesvirus (KSHV) belongs to the Gammaherpesvirinae subfamily. During the lytic phase of herpesviruses, viral capsids form in the host cell nucleus, and the replicated viral genome is packaged into these capsids. The herpesviral genome is replicated as a precursor head-to-tail concatemer consisting of tandemly repeated genomic units, each flanked by terminal repeats (TRs). The herpesvirus terminase complex packages a single genomic unit into a capsid by cleaving the TRs in the precursor genome. Although the terminase complexes of alpha- and beta-herpesviruses are well characterized, the KSHV terminase complex is poorly understood. KSHV ORF7, ORF67.5, and ORF29 are thought to be components of this complex. We previously reported that KSHV deficient in either ORF7 or ORF67.5 formed immature, soccer ball-like capsids and failed to cleave the TRs, resulting in decreased virion production. Moreover, ORF7 interacted with both ORF29 and ORF67.5; however, ORF29 and ORF67.5 did not interact with each other. Thus, although ORF7 and ORF67.5 are important for KSHV terminase function, the function of ORF29 remains largely unknown. In this study, we constructed an ORF29-deficient KSHV and analyzed its virological properties. ORF29 was found to be essential for virion production and TR cleavage. Numerous immature, soccer ball-like capsids were observed in cells harboring ORF29-deficient KSHV. The N-terminal region of ORF29 was important for its interaction with ORF7, although the full-length ORF29 was required for effective assembly of the KSHV terminase complex. Furthermore, ORF29 preferentially interacted with itself rather than with ORF7. Thus, our data show that ORF29 functions as a fundamental component of the terminase complex.IMPORTANCEBecause the role of ORF29 in the Kaposi's sarcoma-associated herpesvirus (KSHV) terminase complex remains unknown, we constructed ORF29-deficient KSHV. Our results demonstrated that ORF29 functions as a component of the KSHV terminase and is essential for mature capsid formation, terminal repeat (TR) cleavage, and terminase complex assembly. Moreover, ORF29 strongly interacted with itself. In herpes simplex virus 1 (HSV-1), the terminase complex (comprising UL15, UL28, and UL33) forms a trimer, and six such trimers assemble into a hexameric ring. The HSV-1 genome passes through this ring and undergoes TR cleavage and genome packaging into a capsid. The self-interaction of ORF29 may be involved in the multimerization of the terminase complex or in the formation of the KSHV terminase ring.

Herpesvirus 8, Human↗

PubMed2004

LAP2alpha and BAF collaborate to organize the Moloney murine leukemia virus preintegration complex.

Integration of viral DNA into the host genome is an essential step in retroviral replication. The viral DNA made by reverse transcription is a component of the preintegration complex (PIC) that also contains the viral integrase protein, the enzyme that integrates the viral DNA. Several other viral and cellular proteins are present in the PIC, but their functional roles are less well established. Barrier-to-autointegration factor (BAF) is a cellular protein component of the PIC that blocks autointegration of the viral DNA and stimulates intermolecular integration. In uninfected cells, BAF interacts with members of the LEM family of inner nuclear membrane and nucleoplasmic proteins. Here, we demonstrate that one of the LEM proteins, lamina-associated polypeptide 2alpha (LAP2alpha), is a component of the PIC. LAP2alpha stabilizes the association of BAF with the PIC to stimulate intermolecular integration and suppress autointegration. To further understand the role of LAP2alpha, we established LAP2alpha-knockdown cell lines. Depletion of LAP2alpha significantly inhibited viral replication. Our results demonstrate a critical contribution of LAP2alpha to the nucleoprotein organization of the PIC and to viral replication.

Animals↗

PubMed2004

Dramatic improvement of respiratory condition after lobectomy for localized bullous emphysema.

A case of dramatic improvement of respiratory function after lobectomy for bullous emphysema with severe hyperinflation of the left lower lobe was reported. A 72-year-old gentleman was admitted to our hospital due to increasing dyspnea with Hugh-Johns class V. His chest X-ray and computed tomography revealed a hyperinflation of the left lower lobe. Despite medication and respiratory rehabilitation, blood gas analysis showed hypercapnia and his symptoms had been progressing. Bronchofiberscopy revealed that the left lower lobe bronchi opened on inspiration and closed on expiration. Since complete destruction of the lower lobe due to air trapping was thought to be the cause of localized hyperinflation and the compression of left upper lobe, left lower lobectomy was performed. His dyspnea immediately disappeared and the respiratory function improved dramatically. We concluded that lobectomy could be considered as one of surgical options in case of complete lobar destruction in emphysema patients.

Aged↗

PubMed2003

Occult lymphoma cells prevalent in autologous marrow from non-Hodgkin's diffuse lymphoma.

The most effective treatment for recurrent non-Hodgkin's lymphoma (NHL) appears to be a high-dose cytotoxic chemotherapy (HDC) followed by autologous bone marrow transplantation (ABMT). However, it has been suggested that the presence of occult lymphoma cells in harvested marrow may be responsible for a significant fraction of treatment failures after HDC/ABMT. The present study examined randomly accrued NHL patients, independent of their cytogenic grades, for the presence of cells bearing bcl-2/immunoglobulin heavy chain (IgH) gene rearrangements in lymph node (LN) biopsies and the bone marrow by polymerase chain reaction (PCR) and Southern blot hybridization combined with a classical culturing technique. Among 41 NHL patients examined, bcl-2/IgH translocations were evident in LN biopsies and marrow from each of 10 follicular lymphoma patients, but not in any samples from 31 newly diagnosed diffuse lymphoma patients. Marrow aspirates from several patients that were cultured using a one-week "triggering culture" followed by an extended period of conventional culture resulted in emergence of a monoclonal, IgH-rearranged, bcl-2-normal lymphoid cell population. Such outgrowth was specifically seen in cultures of diffuse lymphoma marrow (7 of 28 evaluable patients). Southern analysis for IgH rearrangement within LN biopsies and of cells cultured from marrow of individual diffuse lymphoma patients produced identical patterns, suggesting that the occult lymphoma cells present in harvested marrow were derived from the predominant lymphoma cell population represented within involved lymph nodes. The culture of histologically occult lymphoma from diagnostic marrow and analysis of the derived cells by Southern blot hybridization can be used to detect potentially aggressive lymphoma cells within harvested marrow, despite their lack of bcl-2 gene rearrangement.

Adult↗

PubMed2003

Quantitative analysis of human immunodeficiency virus type 1 DNA dynamics by real-time PCR: integration efficiency in stimulated and unstimulated peripheral blood mononuclear cells.

We established a set of real-time PCR assay to accurately quantify human immunodeficiency virus type 1 (HIV-1) DNA in infected cells. Using this assay we were able to measure the strong-stop, full-length/ 1-LTR circle, 2-LTR circle, and integrated forms of viral DNA, and the data provided was quite consistent with the characteristics of mutant viruses in early phase of infection. Since our assay is particularly applicable to quantify the integrated DNA in small scale of samples, we measured the level of integrated DNA in wild-type virus (WT)- or Vpr-defective virus (deltaVpr)-infected peripheral blood mononuclear cells (PBMC), and examined whether quiescent condition of the PBMC influences integration step of HIV-1. Under stimulating condition approximately 25% of total viral DNA was in integrated form in either WT- or DeltaVpr-infected cells. In contrast, under unstimulated condition the level of integration efficiency was not significantly reduced in WT-infected cells, while this efficiency was severely impaired in the absence of vpr gene. This result clearly demonstrated a crucial role of the Vpr for nuclear localization and subsequent integration of viral DNA in nondividing cells. Therefore, our assay is useful for analyzing the events in early phase of HIV-1 infection under various conditions.

Cell Culture Techniques↗

PubMed2002

Isolation and characterization of an infectious HIV type 1 molecular clone from a patient with primary infection.

We isolated a subtype B infectious DNA clone of human immunodeficiency virus type 1 (HIV-1) from a seronegative patient with acute infection and determined the entire nucleotide sequence. All the reading frames encoding the structural proteins (Gag, Pol, and Env) and nonstructural proteins (Tat, Rev, Vpr, Vif, and Nef) were found. Although moat functional domains in these proteins were conserved, we identified a duplication of the T cell factor lei (TCF-1alpha) element in the long terminal repeat and many variations in the N-linked glycosylation sites in the V4-V5 region but not in the V1-V3 loop of Env, compared with prototype subtype B clones. Furthermore, phylogenetic analysis of the entire nucleotide sequence indicated that this HIV-1 was distinct from the prototype subtype B clones, suggesting that transmitted viruses can be variants. This HIV-1 DNA done will be a useful prototype for investigating the mechanism of HIV-1 transmission.

Amino Acid Sequence↗

PubMed2002

Artificial neural network predictive model for allergic disease using single nucleotide polymorphisms data.

The purpose of this study was to develop a novel diagnostic prediction method for allergic diseases from the data of single nucleotide polymorphisms (SNPs) using an artificial neural network (ANN). We applied the prediction method to four allergic diseases, such as atopic dermatitis (AD), allergic conjunctivitis (AC), allergic rhinitis (AR) and bronchial asthma (BA), and verified its predictive ability. Almost all the learning data were precisely predicted. Regarding the evaluation data, the learned ANN model could correctly predict a diagnosis with more than 78% accuracy. We also analyzed the SNP data using multiple regression analysis (MRA). Using the MRA model, less than 10% of patients with the above allergic diseases were correctly diagnosed, while this figure was more than 75% for persons without allergic diseases. From these results, it was shown that the ANN model was superior to the MRA model with respect to predictive ability of allergic diseases. Moreover, we used two different methods to convert the genetic polymorphism data into numerical data. Using both methods, diagnostic predictions were quite precise and almost the same predictive abilities were observed. This is the first study showing the application and usefulness of an ANN for the prediction of allergic diseases based on SNP data.

Journal Article↗

PubMed2002

Regulatory mechanisms by which barrier-to-autointegration factor blocks autointegration and stimulates intermolecular integration of Moloney murine leukemia virus preintegration complexes.

Retroviral integration is mediated by a preintegration complex (PIC) which contains the viral DNA made by reverse transcription together with associated protein factors. Prior to association with target DNA, the PIC must avoid suicidal intramolecular integration of its viral DNA (autointegration). We have demonstrated that barrier-to-autointegration factor (BAF) blocks the autointegration of Moloney murine leukemia virus (MoMLV) PICs in vitro. In this study, we show that BAF is an authentic component of MoMLV. Analysis of the sedimentation properties of initial, salt-stripped, and BAF-reconstituted PICs reveals that the viral DNA within the PIC is reversibly compacted by BAF, consistent with the functional role of BAF in protecting the viral DNA from autointegration. Furthermore, we find that BAF can promote the association of PICs with target DNA. Thus, our data suggest that BAF plays critical roles in promoting preferential intermolecular integration by both blocking autointegration and stimulating the capture of target DNA.

3T3 Cells↗