Biomedical subjects

T Matsuda

Publications and source records attributed to T Matsuda.

At least 163 records · Page 9Linked to original sources

PubMed2000

Molecular cloning and expression of the mouse N-acetylneuraminic acid 9-phosphate synthase which does not have deaminoneuraminic acid (KDN) 9-phosphate synthase activity.

A cDNA of the mouse homologue of Escherichia coli N-acetylneuraminic acid (Neu5Ac) synthase (neuB gene product) was cloned by the PCR-based method. The mouse homologue consists of 359 amino acids, and the cDNA sequence displays 33% identity to that of the E. coli Neu5Ac synthase. The recombinant mouse homologue which is transiently expressed in HeLa cells does not exhibit the Neu5Ac synthase activity, which catalyzes condensation of phosphoenolpyruvate (PEP) and N-acetylmannosamine (ManNAc) to synthesize Neu5Ac, but the Neu5Ac 9-phosphate (Neu5Ac-9-P) synthase activity, which catalyzes condensation of PEP and ManNAc 6-phosphate (ManNAc-6-P) to synthesize Neu5Ac-9-P. Thus, the mouse homologue of E. coli Neu5Ac synthase is the Neu5Ac-9-P synthase. The Neu5Ac-9-P synthase is a cytosolic enzyme and ubiquitously distributed in mouse various tissues. Notably, the Neu5Ac-9-P synthase can not catalyze the synthesis of deaminoneuraminic acid (KDN) or KDN-9-P from PEP and Man or ManNAc-6-P, thus suggesting that the enzyme is not involved in the synthesis of KDN. This is consistent with the previous observation that only a very low activity to synthesize KDN is found in mouse B16 cells [Angata, T., et al. (1999) Biochem. Biophys. Res. Commun. 261, 326-331].

Amino Acid Sequence↗

PubMed2000

T-588 inhibits astrocyte apoptosis via mitogen-activated protein kinase signal pathway.

The effect of (1R)-1-benzo[b]thiophen-5-yl-2-[2-(diethylamino)ethoxy]ethan -1-ol hydrochloride (T-588), a cognition enhancer, on reperfusion injury was studied in cultured rat astrocytes. T-588 at 1-10 microM partially protected astrocytes against reperfusion injury after exposure to Ca(2+)-free medium or hydrogen peroxide. Nerve growth factor (NGF) had a similar protective effect. Addition of both T-588 and NGF resulted in complete protection against Ca(2+) reperfusion injury. T-588 did not stimulate NGF production in astrocytes. The effect of T-588 on Ca(2+) reperfusion injury including apoptosis was inhibited by the mitogen-activated protein (MAP)/extracellular signal-regulated kinase (ERK) kinase inhibitor 2'-amino-3'-methoxyflavone (PD98059), but not by the phosphoinositide 3-kinase inhibitor wortmannin. The effect of NGF was inhibited by PD98059 and wortmannin. T-588 stimulated rapidly the phosphorylation of ERK, but did not affect that of Akt in astrocytes. These findings suggest that the ERK MAP kinase pathway has a role in the protective effects of T-588 and NGF.

Androstadienes↗

PubMed2000

Helicity dependence of gammap --> Npi below 450 MeV and contribution to the Gerasimov-Drell-Hearn sum rule.

The helicity dependence of the single pion photoproduction on the proton has been measured in the energy range from 200 to 450 MeV for the first time. The experiment, performed at the Mainz microtron MAMI, used a 4pi-detector system, a circularly polarized, tagged photon beam, and a frozen-spin target. The data obtained provide new information for multipole analyses of pion photoproduction and determine the main contributions to the Gerasimov-Drell-Hearn sum rule and the forward spin polarizability gamma(0).

Journal Article↗

PubMed2000

Lineage-specific regulation of the murine RAG-2 promoter: GATA-3 in T cells and Pax-5 in B cells.

Recombination activating gene-1 (RAG-1) and RAG-2 are expressed in lymphoid cells undergoing the antigen receptor gene rearrangement. A study of the regulation of the mouse RAG-2 promoter showed that the lymphocyte-specific promoter activity is conferred 80 nucleotide (nt) upstream of RAG-2. Using an electrophoretic mobility shift assay, it was shown that a B-cell-specific transcription protein, Pax-5, and a T-cell-specific transcription protein, GATA-3, bind to the -80 to -17 nt region in B cells and T cells, respectively. Mutation of the RAG-2 promoter for Pax-5- and GATA-3-binding sites results in the reduction of promoter activity in B cells and T cells. These results indicate that distinct DNA binding proteins, Pax-5 and GATA-3, may regulate the murine RAG-2 promoter in B and T lineage cells, respectively. (Blood. 2000;95:3845-3852)

Animals↗

PubMed2000

Single low-dose administration of human recombinant hepatocyte growth factor attenuates intimal hyperplasia in a balloon-injured rabbit iliac artery model.

BACKGROUND: Previous studies have shown that repeated systemic administration of human recombinant hepatocyte growth factor (hrHGF) in mg/kg levels modulates the wound-healing process in various diseases. Recently, HGF has been characterized as one of the most potent endothelial-cell-specific growth factors. We tested our hypothesis that local delivery of hrHGF, even at low microg/kg levels (> or =2 orders of magnitude lower than systemically administered doses), might attenuate neointimal hyperplasia in response to vascular injury via accelerated reendothelialization. METHODS AND RESULTS: The iliac artery was denuded in 16 New Zealand White rabbits (3 kg), followed by administration, via a drug delivery catheter, of either hrHGF (10 microg; n = 11) or control vehicle (n=5) over 20 minutes. In pilot studies using this device, the drug permeated into the medial tissues, where it persisted for > or =24 hours. Four weeks after the local delivery of hrHGF, computer-assisted morphometric analysis revealed significant reduction in the intimal area (hrHGF, 0.37+/-0.21 versus control, 0.68+/-0.16 mm(2), mean +/- SD; P<0.05) but no change in the medial area (hrHGF, 1.03+/-0.21 versus control, 1.10+/-0.52 mm(2)). Scanning electron microscopy revealed extensive endothelialization with regular and confluent endothelial cell layer regeneration in the hrHGF-treated vessels. CONCLUSIONS: Accelerated endothelialization after local delivery of hrHGF, a novel and potent endothelial cell mitogen, effectively attenuates neointimal proliferation even after single low-dose administration. This observation could have potential therapeutic implications in the prevention of restenosis after angioplasty.

Animals↗

PubMed2000

Frequent occurrence of pre-existing alpha 2-->8-linked disialic and oligosialic acids with chain lengths up to 7 Sia residues in mammalian brain glycoproteins. Prevalence revealed by highly sensitive chemical methods and anti-di-, oligo-, and poly-Sia antibodies specific for defined chain lengths.

The pre-existence of alpha2-->8-linked disialic acid (di-Sia) and oligosialic acid (oligo-Sia) structures with up to 7 Sia residues was shown to occur on a large number of brain glycoproteins, including neural cell adhesion molecules (N-CAMs), by two highly sensitive chemical methods (Sato, C., Inoue, S., Matsuda, T., and Kitajima, K. (1998) Anal. Biochem. 261, 191-197; Sato, C., Inoue, S., Matsuda, T., and Kitajima, K. (1999) Anal. Biochem. 266, 102-109). This unexpected finding was also confirmed using a newly developed antibody prepared using a copolymer of alpha2-->8-linked N-acetylneuraminyl p-vinylbenzylamide and acrylamide as an immunogen and known antibodies whose immunospecificities were determined to be di- and oligo-Sia residues with defined chain lengths. The major significance of the new finding that di- and oligo-Sia chains exist on a large number of brain glycoproteins is 2-fold. First, it reveals a surprising diversity in the number and M(r) of proteins distinct from N-CAM that are covalently modified by these short sialyl glycotopes. Second, it suggests that synthesis of di- and/or oligo-Sia units may be catalyzed by alpha2-->8-sialyltransferase(s) that are distinct from the known polysialyltransferases, STX and PST, which are partially responsible for polysialylation of N-CAM.

Animals↗

PubMed2000

Spontaneous galactosylation of agalactoglycoproteins in colostrum.

We have found that spontaneous galactosylation of GlcNAc residues occurs in bovine colostrum, but not in dialyzed colostrum, without adding UDP-Gal as a donor substrate. UDP-Gal was shown to be present in bovine colostrum at a level ranging from 200 to 600 microM. When a tracer UDP-[(14)C]Gal was added to the dialyzed colostrum together with a Gal beta1,4-specific beta-galactosidase, remarkable incorporation of radioactivity into 24-28 kDa and 33 kDa RCA1-positive glycoproteins was demonstrated by SDS-PAGE/autoradiography. Some 100-140 kDa agalactoglycoproteins of a CHO mutant cell line were also galactosylated on a blotted membrane by the incubation in the colostrum.

Animals↗

PubMed2000

SOCS-1 can suppress CD3zeta- and Syk-mediated NF-AT activation in a non-lymphoid cell line.

To elucidate T cell antigen receptor (TCR) signaling leading to activation nuclear factor of activated T cells (NF-AT), we reconstituted TCR signaling to activate NF-AT in a non-lymphoid cell line, 293T. We demonstrated that co-expression of CD8/zeta and Syk were necessary for NF-AT activation in 293T. This NF-AT response was completely inhibited by the addition of cyclosporin A or FK506, but markedly enhanced by the additional expression of Tec protein tyrosine kinase. We also show that the cytokine signaling suppressor, suppressor of cytokine signaling 1, potently inhibited this response by interacting with Syk and immunoreceptor tyrosine-based activation motifs in CD8/zeta. These results imply that this novel system may provide a useful tool to delineate or identify the regulatory molecules for CD3zeta/Syk-mediated NF-AT activation.

CD3 Complex↗

PubMed2000

Low fidelity DNA synthesis by human DNA polymerase-eta.

A superfamily of DNA polymerases that bypass lesions in DNA has been described. Some family members are described as error-prone because mutations that inactivate the polymerase reduce damage-induced mutagenesis. In contrast, mutations in the skin cancer susceptibility gene XPV, which encodes DNA polymerase (pol)-eta, lead to increased ultraviolet-induced mutagenesis. This, and the fact that pol-eta primarily inserts adenines during efficient bypass of thymine-thymine dimers in vitro, has led to the description of pol-eta as error-free. However, here we show that human pol-eta copies undamaged DNA with much lower fidelity than any other template-dependent DNA polymerase studied. Pol-eta lacks an intrinsic proofreading exonuclease activity and, depending on the mismatch, makes one base substitution error for every 18 to 380 nucleotides synthesized. This very low fidelity indicates a relaxed requirement for correct base pairing geometry and indicates that the function of pol-eta may be tightly controlled to prevent potentially mutagenic DNA synthesis.

DNA↗

PubMed2000

[Laparoscopic radical nephrectomy for renal cell carcinomas; report on two initial cases].

We recently performed a laparoscopic radical nephrectomy (LRN) on two patients with a renal cell carcinoma. Case 1, a 72-year-old man, was diagnosed as having a renal cell carcinoma 2.5 cm in diameter in the right kidney, and also a submucosal tumor of the cecum. LRN and laparoscopically assisted ileocecal resection were performed using a transperitoneal approach on September 28, 1999. Total operation time and blood loss during the operation were 308 minutes and 320 ml, respectively. The operation time needed for LRN, which was calculated as the total operation time minus the time spent on ileocecal resection, was 199 minutes. There were no complications after surgery, and the patient was recommended for discharge on the 7th postoperative day, but was actually discharged on the 10th postoperative day. Case 2, an 81-year-old man, was diagnosed as having a renal cell carcinoma 3.0 cm in diameter in the right kidney. He had been undergone a total gastrectomy for a gastric carcinoma at age 77, and a sigmoidectomy for a sigmoid colon carcinoma at age 79. A transperitoneal approach was applied for LRN to detect any recurrence of previous carcinomas on September 30, 1999. During adhesiolytic procedures, the colon was injured due to an inappropriate maneuver of the grasping forceps. A small laparotomy (5 cm) was required for repair of the colon. The total operation time and blood loss during surgery were 370 minutes and 850 ml. The operation time calculated from the video of LRN was 274 minutes. Two additional surgical procedures were required in this case. The first was for a postoperative intraperitoneal hemorrhage due to the hemoclip dropping out of the small vein. The second was for hemorrhage in the abdominal wall. Fortunately, the clinical course after surgery was good and the patient was discharged on the 8th postoperative day. There were no complications in case 1. Omitting ileocecal resection was considered to speed up oral intake, leading to earlier discharge. However, major complications occurred in case 2. It is important to clarify the cause of postoperative hemorrhage by careful observation of the video recording, in order to suggest safer procedures in laparoscopic surgery. Although these are only two LRN experiences, we are convinced that LRN can improve postoperative QOL (Quality of life) and is an acceptable alternative for the treatment of renal cell carcinomas.

Aged↗

PubMed2000

Suppression of heat shock protein-70 by ceramide in heat shock-induced HL-60 cell apoptosis.

Ceramide has emerged as a mediator of cell growth, differentiation, and apoptosis in many biological systems. Many kinds of stresses are reported to induce apoptosis with an increase of ceramide generation. Here we showed that the intracellular ceramide levels increased in parallel with heat shock (HS)-induced apoptosis in an intensity- and time-dependent manner, and synthetic N-acetylsphingosine (C(2)-ceramide) synergistically enhanced HS-induced apoptosis in HL-60 cells. In order to know the role of ceramide generation in HS-induced apoptosis, we examined the effects of C(2)-ceramide on the levels of mRNA and protein of heat shock proteins (HSPs). The increase of HSP-70 mRNA levels 1-2 h after HS at 42 degrees C for 30 min was suppressed by C(2)-ceramide in a dose-dependent manner. In comparison with HSP-70, the levels of HSP-60 and -90 mRNAs were faintly suppressed by C(2)-ceramide. Similarly, the increase in the protein levels of HSP-70 was significantly suppressed 4-8 h after HS by C(2)-ceramide in a dose-dependent manner. Additionally, in 293 cells, which are constitutively overexpressing HSP-70 gene, the levels of HSP-70 mRNA were suppressed by C(2)-ceramide in parallel with the increase of apoptotic cells. We next examined the mechanisms by which C(2)-ceramide suppressed HS-increased HSP-70 expression. The treatment with C(2)-ceramide did not affect both an activation of a nuclear transcription factor for HSP-70, heat shock factor-1, and an increased transcriptional rate of HSP-70 by HS, but increased the rates of HSP-70 mRNA degradation. In summary, ceramide may efficiently induce HS-induced apoptosis by suppressing anti-apoptotic HSP-70 through a post-transcriptional regulation.

Apoptosis↗

PubMed2000

Role of c-jun expression increased by heat shock- and ceramide-activated caspase-3 in HL-60 cell apoptosis. Possible involvement of ceramide in heat shock-induced apoptosis.

Ceramide has emerged as a lipid mediator in apoptosis induced by a variety of stresses. As we previously showed that the activation of AP-1, a nuclear transcription factor was indispensable to ceramide-induced apoptosis in human leukemia HL-60 cells (Sawai, H., Okazaki, T., Yamamoto, H., Okano, H., Takeda, Y., Tashima, M., Sawada, H., Okuma, M., Ishikura, H., Umehara, H., and Domae, N. (1995) J. Biol. Chem. 270, 27326-27331), the role and mechanism of heat shock (HS)-increased c-jun expression in apoptosis was here investigated. HS increased morphological changes compatible with apoptosis in human leukemia HL-60 cells, and induced ceramide generation and sphingomyelin hydrolysis with an increase of neutral magnesium-dependent sphingomyelinase activity. When HS failed to induce apoptosis in HS-resistant HL-60 cells, ceramide generation was not detected, suggesting that ceramide was involved in downstream signals required for HS-induced apoptosis. Both HS and N-acetylsphingosine (C(2)-ceramide) increased the expression of c-jun/c-fos mRNAs with the peak 2 h after treatment. When we examined whether the inhibition of c-jun expression by its antisense oligodeoxynucleotides (AS) blocked HS- or C(2)-ceramide-induced apoptosis, AS of c-jun gene inhibited apoptotic morphological changes and DNA fragmentation whereas did not sense oligodeoxynucleotides. Moreover, a synthetic tetrapeptide, acetyl-Asp-Met-Gln-Asp-aldehyde (DMQD-CHO), which inhibited the formation of active form of caspase-3 more efficiently than those of caspase-4, -6, -7, and -8, blocked both caspase-3 like activity, c-jun expression and apoptosis induced by HS or C(2)-ceramide, although DMQD-CHO did not affect HS-induced ceramide generation. These results suggested that the ceramide was generated through sphingomyelin hydrolysis by HS-activated neutral, magnesium-dependent sphingomyelinase and that subsequent c-jun expression through activation of caspase-3 played a role in HS-induced HL-60 cell apoptosis.

Apoptosis↗

PubMed2000

L-lactate inhibits L-cystine/L-glutamate exchange transport and decreases glutathione content in rat cultured astrocytes.

In several brain pathologies, the level of brain L-lactate increases. The stimulation of L-lactate production is a detrimental factor in promoting neuronal cell damage and astrocytic dysfunction. Astrocytic glutathione metabolism has an important role to protect brain cells against oxidative stress. In this study, effects of L-lactate on L-cystine uptake and glutathione level in rat-cultured astrocytes were examined. L-Lactate decreased the L-(35)S-cystine and Na(+)-independent L-(3)H-glutamate uptakes into astrocytes at the concentrations more than 2.5 mM. The L-lactate-induced decrease in L-(35)S-cystine uptake was neither affected by modification of extracellular pH nor mimicked by acetate, propionate and butyrate. The apparent Km value of the L-(35)S-cystine uptake was increased by L-lactate, while the Vmax was not changed. Astrocytic glutathione and nonprotein thiol content was decreased by incubation with 20 mM L-lactate for 48 hours (65% and 75% of control values, respectively). The decreases in astrocytic glutathione and nonprotein thiol content were restored to normal levels by withdrawal of L-lactate. These results suggest that L-lactate inhibits astrocytic L-cystine/L-glutamate exchangers and affects the glutathione contents.

Animals↗

PubMed2000

Two classes of enzymes of opposite stereochemistry in an organism: one for fluorinated and another for nonfluorinated substrates.

Reduction of methyl ketones by dried cells of Geotrichum candidum (APG4) afforded (S)-alcohols in excellent enantiomeric excess (ee), whereas the reduction of trifluoromethyl ketones gave the corresponding alcohols of the opposite configuration also in excellent ee. The replacement of the methyl moiety with a trifluoromethyl group alters both the bulkiness and the electronic properties, the effect of which on the stereoselectivity was examined. No inversion in stereochemistry was observed in the reduction of hindered ketones such as isopropyl ketone, while the stereoselectivity was inverted in the reduction of ketones with electron-withdrawing atoms such as chlorine. The mechanism for the inversion in stereochemistry was investigated by enzymatic studies. Several enzymes with different stereoselectivities were isolated; one of them catalyzed the reduction of methyl ketones, and another with the opposite stereoselectivity catalyzed the reduction of trifluoromethyl ketones. Furthermore, both APG4 and the isolated enzyme were applied to the reduction of fluorinated ketones on a preparative scale, which resulted in the synthesis of chiral fluorinated alcohols with excellent ee.

Fluorine↗

PubMed2000

Reduction of resuscitation fluid volumes in severely burned patients using ascorbic acid administration: a randomized, prospective study.

HYPOTHESIS: High-dose ascorbic acid (vitamin C) therapy (66 mg/kg per hour) attenuates postburn lipid peroxidation, resuscitation fluid volume requirements, and edema generation in severely burned patients. STUDY DESIGN AND SETTING: A prospective, randomized study at a university trauma and critical care center in Japan. SUBJECTS AND METHODS: Thirty-seven patients with burns over more than 30% of their total body surface area (TBSA) hospitalized within 2 hours after injury were randomly divided into ascorbic acid and control groups. Fluid resuscitation was performed using Ringer lactate solution to maintain stable hemodynamic measurements and adequate urine output (0.5-1.0 ml/kg per hour). In the ascorbic acid group (n = 19; mean burn size, 63% +/- 26% TBSA; mean burn index, 57 +/- 26; inhalation injury, 15/ 19), ascorbic acid was infused during the initial 24-hour study period. In the control group (n = 18; mean burn size, 53% +/- 17% TBSA; mean burn index, 47 +/- 13; inhalation injury, 12/18), no ascorbic acid was infused. We compared hemodynamic and respiratory measurements, lipid peroxidation, and fluid balance for 96 hours after injury. Two-way analysis of variance and Tukey test were used to analyze the data. RESULTS: Heart rate, mean arterial pressure, central venous pressure, arterial pH, base deficit, and urine outputs were equivalent in both groups. The 24-hour total fluid infusion volumes in the control and ascorbic acid groups were 5.5 +/- 3.1 and 3.0 +/- 1.7 mL/kg per percentage of burn area, respectively (P<.01). In the first 24 hours, the ascorbic acid group gained 9.2% +/- 8.2% of pretreatment weight; controls, 17.8% +/- 6.9%. Burned tissue water content was 6.1 +/- 1.8 vs 2.6 +/- 1.7 mL/g of dry weight in the control and ascorbic acid groups, respectively (P<.01). Fluid retention in the second 24 hours was also significantly reduced in the ascorbic acid group. In the control group, the ratio of PaO2 to fraction of inspired oxygen at 18, 24, 36, 48, and 72 hours after injury was less than that of the ascorbic acid group (P<.01). The length of mechanical ventilation in the control and ascorbic acid groups was 21.3 +/- 15.6 and 12.1 +/- 8.8 days, respectively (P<.05). Serum malondialdehyde levels were lower in the ascorbic acid group at 18, 24, and 36 hours after injury (P<.05). CONCLUSIONS: Adjuvant administration of high-dose ascorbic acid during the first 24 hours after thermal injury significantly reduces resuscitation fluid volume requirements, body weight gain, and wound edema. A reduction in the severity of respiratory dysfunction was also apparent in these patients.

Adolescent↗

PubMed2000

Laboratory-scale mass production of a multi-micropatterned grafted surface with different polymer regions.

In this article, we demonstrate laboratory-scale mass production of a regionally precise multi-micropatterned surface photo-graft-copolymerized with three water-soluble monomers based on the photochemistry of an iniferter, which means that it acts as an initiator, a transfer agent and a terminator, benzyl N, N-diethyldithiocarbamate. The surface was semi-automatically prepared using a combination of a custom-designed irradiation apparatus installed with a motor-controlled stage for a substrate and three photomasks with different line-patterned slits (number of slits 20, width 500 microm, length 10 mm), and carbon dioxide laser cutting apparatus. A particular region of poly(styrene-co-vinylbenzyl N,N-diethyldithiocarbamate) coated on a PET film was irradiated in a particular aqueous monomer solution while moving the irradiated portion stepwise after irradiation through each line of the photomask. Photo-graft-copolymerization was carried out sequentially with acrylic acid sodium salt (AANa), N-[3-(dimethylamino)propyl]acrylamide methiodide (DMAPAAm), and acrylamide (AAm) using differently patterned photomasks. Characterization of surface elemental distribution by X-ray photoelectron spectroscopy (XPS), and light microscopic visualization by dye staining revealed a microprocessed surface with 20 sets of micropatterns, each of which had three line regions grafted with three different polymers. The irradiation of a carbon dioxide laser manipulated via computer-aided design (CAD) software onto the microprocessed surface resulted in automatic circular cutting for each set of micropatterns to mass-produce multi-micropatterned substrates for the study of substrate-dependent endothelial cell responses.

Animals↗

PubMed2000

Inhibitory effect of statins on fetal bovine serum-induced proliferation of rat cultured mesangial cells and correlation between their inhibitory effect and transport characteristics.

Mesangial cells play an important role in physiologic functions, including the regulation of glomerular filtration, and as a pathogenic factor for proliferative glomerulonephritis. We compared the potencies of the inhibitory effects of simvastatin acid, lovastatin acid, and pravastatin on fetal bovine serum (FBS)-induced proliferation of rat cultured mesangial cells, and examined the correlation between their inhibitory effects and intracellular concentrations. We also investigated the transport of the statins in the cells, and whether or not their intracellular concentrations were determined by their transport characteristics. It appeared that the growth inhibitory effects on FBS-induced proliferation of mesangial cells of simvastatin acid and lovastatin acid were approximately the same, but that of pravastatin was extremely weak compared with the others. The growth inhibitory effects of these agents were suggested to depend, at least in part, on the amount incorporated intracellularly. Simvastatin acid, lovastatin acid, and pravastatin appeared to be taken up by mesangial cells via a common carrier, the uptake capacity being determined by their lipophilicity. Therefore, it was thought that the growth inhibitory effects of the statins partially depended on their carrier-mediated uptake by mesangial cells.

Animals↗

PubMed2000

Lactate dehydrogenase A-dependent surface expression of immature thymocyte antigen-1: an implication for a novel trafficking function of lactate dehydrogenase-A during T cell development.

A possible involvement of lactate dehydrogenase A (LDHA) in the translocation of a thymic differentiation antigen, immature thymocyte antigen-1 (IMT-1), from cytoplasm to cell surface membrane during thymocyte differentiation is described. Transfection of cDNA for LDHA, but not LDHB, into EL4 cells, which expressed IMT-1 in the cytoplasm but not on the cell surface, induced the expression of IMT-1 on the cell surface. This translocation process seemed to be dependent on the translation of LDHA cDNA in EL4 cells, as well as the native structure of LDHA composing of coenzyme binding domain, catalysis domain, and subunit contact domain. Immunoprecipitation analysis revealed that LDHA could be co-precipitated with IMT-1 from the cell surface of EL4 cells that had been transfected with LDHA cDNA, suggesting that some of LDHA is associated with cell surface IMT-1 on the transfectants. Flow cytometry analysis of thymocyte subpopulations showed that some thymocytes at the CD4(-)CD8(-) double negative stage express both IMT-1 and LDHA on their surface. These data indicate that LDHA, in addition to its function in the metabolism in the glycolytic pathway, may have a novel function in the expression of a cell surface antigen during T cell development.

Animals↗