Biomedical subjects

Shinichi Kojima

Publications and source records attributed to Shinichi Kojima.

5 recordsLinked to original sources

PubMed2007

Two-dimensional differential gel electrophoresis of rat heart proteins in ischemia and ischemia-reperfusion.

Ischemia-reperfusion injury occurs in acute myocardial infarction, cardiopulmonary bypass surgery, and heart transplantation. However the precise mechanisms still remain unclear. In order to identify proteins that are involved in ischemia-reperfusion injury, we compared precipitated 100,000g fractions of normal, ischemic, and ischemic-reperfused rat hearts using two-dimensional (2D) difference gel electrophoresis (2D-DIGE). 2D-DIGE is reliable method to define quantitative protein differences, especially when subtle protein changes are under investigation. In this study, six spots that changed more than twofold and two additional spots related to these spots were detected. Five of the spots were identified by matrix-assisted laser desorption/ionization time of flight mass spectrometry as protein disulfide isomerase, one as 60 kDa heat-shock protein, and two as elongation factor Tu.

Animals↗

PubMed2005

18O-labeling quantitative proteomics using an ion trap mass spectrometer.

We describe a method for simultaneous identification and quantitation of proteins within complex mixtures. The method consists of 18O-labeling, a simple stable isotope-coding that requires merely enzymatic digestion in 18O-water, in combination with a capillary-liquid chromatography electrospray ion-trap mass spectrometer. In a separate experiment using the same sample and a spike test, we demonstrate that the difference ration was calculated accurately using the 18O-labeling method even if the protein was part of a complex mixture. Our data also suggest that the accuracy of the quantitation can be improved by averaging the difference ratios of several peptides. In comparing our method with the isotope-coded affinity tag (ICAT) method, we show that the 18O-labeling method has the advantages of better recovery and fewer isotope effects. Therefore, the 18O-labeling method is a powerful tool for large-scale proteomics applications.

Animals↗

PubMed2004

Identification of major proteins in the lipid droplet-enriched fraction isolated from the human hepatocyte cell line HuH7.

Recent studies have revealed the presence of intracellular lipid droplets in wide variety of species. In mammalian cells, there exist proteins specifically localize in lipid droplets. However, the protein profile in the droplet remains yet to be clarified. In this study, a fraction enriched with lipid droplets was isolated from a human hepatocyte cell line HuH7 using sucrose density gradient centrifugation, and 17 major proteins in the fraction were identified using nano LC-MS/MS techniques. Adipose differentiation-related protein (ADRP) was the most abundant protein in the fraction. The secondary abundant proteins were identified to be acyl-CoA synthetase 3 (ACS3) and 17beta-hydroxysteroid dehydrogenase 11 (17betaHSD11). Included in the identified proteins were five lipid-metabolizing enzymes as well as two lipid droplet-specific proteins. When HuH7 cell lysate was fractionated by a density gradient, most of 17betaHSD11 was found in the droplet-enriched fraction. In immunocytochemical analysis, 17betaHSD11 showed ring-shaped images which overlapped with those for ADRP. These results suggest that a specific set of proteins is enriched in the lipid droplet-enriched fraction and that 17betaHSD11 localizes specifically in the fraction.

17-Hydroxysteroid Dehydrogenases↗

PubMed2003

Cutting edge: Requirement for growth hormone-releasing hormone in the development of experimental autoimmune encephalomyelitis.

Growth hormone (GH)-releasing hormone (GHRH) is a neuropeptide that stimulates secretion of GH from the pituitary gland. Although GHRH and its receptor (GHRHR) are expressed in leukocytes, physiological function of GHRH in the immune system remains unclear. To study the influence of GHRH in autoimmunity, susceptibility to experimental autoimmune encephalomyelitis (EAE) was examined in C57BL/6J-Ghrhr(lit/lit) (lit/lit), mice deficient in the GHRHR gene. We found that lit/lit mice were resistant to myelin oligodendrocyte glycoprotein (MOG)-induced EAE. Splenocytes from MOG-immunized lit/lit mice proliferated normally in response to MOG peptide, suggesting that activation of MOG-specific T cells in GHRHR-deficient mice is not impaired. Our data strongly suggest that GHRH plays a crucial role in the development of EAE and may provide the basis for a novel therapeutic approach protecting from autoimmune diseases.

Amino Acid Sequence↗

PubMed2003

Proteomic analysis of rat heart in ischemia and ischemia-reperfusion using fluorescence two-dimensional difference gel electrophoresis.

Ischemia-reperfusion injury is a major complication occurring in acute myocardial infarction, cardiopulmonary bypass surgery, and heart transplantation. The aim of this study was to identify proteins that were involved in ischemia-reperfusion injury using fluorescence two-dimensional difference gel electrophoresis. We compared the 100,000 x g precipitate fractions of normal, ischemic and ischemia-reperfused rat hearts and detected six spots which changed more than two-fold in expression level and two additional spots related to these spots. Using peptide mass fingerprinting by matrix-assisted laser desorption/ionization-time of flight mass spectrometry, we identified five of these spots as protein disulfide isomerase A3 (PDA3), one as 60 kDa heat shock protein (HSP60) and two as elongation factor Tu (EF-Tu). HSP60 was increased during ischemia and decreased to normal expression level after reperfusion. EF-Tu was increased in ischemia but not decreased by reperfusion. We also found that several protein spots of PDA3 shifted towards a higher isoelectric point in ischemia and ischemia-reperfusion. Our data strongly suggested that PDA3 underwent dephosphorylation during ischemia and reperfusion and serine 343 of PDA3 was one of the phosphorylation sites.

Animals↗