Biomedical subjects

Masafumi Yamada

Publications and source records attributed to Masafumi Yamada.

3 recordsLinked to original sources

PubMed2003

Tracking gene expression in primary immunodeficiencies.

PURPOSE OF REVIEW: Extensive research on molecular genetics in recent decades has provided a wealth of information about the mechanisms of primary immunodeficiency diseases. Microarray technology enables the survey of the expression of thousands of genes simultaneously. This review focuses on the commonly used arrays and initial applications in the study of primary immunodeficiency diseases. The application of this technology has been found to accelerate the discovery rate of gene expression disturbances in primary immunodeficiency diseases and provide potential molecular diagnostic tools. RECENT FINDINGS: The important role of microarray technology in functional genomic study has been demonstrated by the exponential growth in the number of scientific publications in the last few years. Microarray analysis has been used to study gene expression in several immunodeficiency diseases with known gene mutations as well as those with unknown causes. It has provided snapshots of gene expression and has presented the molecular phenotypes in the cells at defined times and under certain stimulation conditions. Studies comparing differential gene expression in patients and normal controls have allowed us to better understand the immunodeficiencies at the molecular level. SUMMARY: Application of microarray technology in immunodeficiency study has facilitated tracking the expression of thousands of genes simultaneously. The molecular phenotypes obtained from microarray results can be used in diagnosis of diseases, supplemental to clinical phenotypes. It is a powerful survey tool that can detect disturbed gene expression in immunodeficiency diseases, which will provide clues for disease gene discovery and potential targets for drug development.

B-Lymphocytes↗

PubMed2002

Mixed chimera status of 12 patients with Wiskott-Aldrich syndrome (WAS) after hematopoietic stem cell transplantation: evaluation by flow cytometric analysis of intracellular WAS protein expression.

Wiskott-Aldrich syndrome (WAS) is caused by defects in the WAS protein (WASP) gene on the X chromosome. We previously reported that flow cytometric analysis of intracellular WASP expression (FCM-WASP) was useful in the diagnosis of WAS in patients and carriers. In this study, we applied FCM-WASP to evaluate the mixed chimera (MC) status of 12 WAS patients who underwent hematopoietic stem cell transplantation (HST). After HST, donor- and recipient-derived peripheral blood mononuclear cells (PBMCs) could be distinguished easily with this method, since the donor cells were WASP(bright), whereas the defective recipient cells were WASP(dim). Furthermore, with use of 2-color FCM-WASP, the MC status could be characterized by cell lineage. Six of the 12 patients with WAS were found to have MC status after HST, whereas others had complete chimera status. MC status was observed in every cell lineage examined. However, among PBMCs, recipient cells were most commonly observed in the monocyte population. Finally, to investigate the naive/memory status of donor and recipient T cells in these patients, 3-color FCM-WASP using anti-CD45RA or CD45RO was performed. We found that, in contrast to WASP(bright) T cells, most WASP(dim) T cells remained naive (CD45RA(+)/RO(-)) more than a year after HST. No imbalance in the ratio of naive to memory T cells was observed in WAS patients before HST. We conclude that FCM-WASP is a potentially useful method for clinical follow-up of WAS patients who have undergone HST. Our findings may also have important implications for the role of WASP during hematopoietic development.

Antigens, CD20↗

PubMed2002

Role of pRB-family/E2F complex in the inhibition of IL-3-dependent lymphoid cell proliferation.

Interleukin 3 (IL-3)-dependent proliferation of haematopoietic cells is specifically inhibited by p130, a member of the pRB-family proteins. p130 interacts with the cell-cycle regulatory E2F transcription factors, notably E2F-4 and E2F-5, and affects promoters containing E2F-binding sites through two distinct mechanisms. First, upon complex formation with E2F, it blocks transcriptional activation by E2F. Second, the formed p130-E2F complex binds to E2F sites and actively represses transcription by inhibiting the activity of surrounding enhancer elements on the promoter. To pursue the relative contributions of each mechanism in the p130-mediated inhibition of IL-3-dependent cell proliferation, we employed a dominant-negative DP-1, which suppresses both E2F-dependent transactivation and the formation of active transcriptional repressors. Ectopic expression of the dominant negative DP-1 in the IL-3-dependent BaF3 lymphoid cells gave rise to an inhibition of cell proliferation, which was concomitantly associated with a decrease in levels of cyclin E, an indispensable molecule for G1 to S-phase cell-cycle progression. Our results indicate that blocking E2F-dependent transactivation, but not the formation of p130-E2F transcriptional repressor complexes, is responsible for the inhibition of IL-3-dependent cell growth by p130.

Animals↗