Physiologically based pharmacokinetics of digoxin in mdr1a knockout mice

To determine the contribution of the mdr1a gene product to digoxin pharmacokinetics, we constructed a physiologically based pharmacokinetic model for digoxin in mdr1a (-/-) and mdr1a (+/+) mice. After intravenous administration, total body clearance and tissue-to-plasma concentration ratios for muscle and heart were decreased in mdr1a (-/-) mice as compared with mdr1a (+/+) mice, and in particular, the digoxin concentration in the brain was 68-fold higher than that in mdr1a (+/+) mice at 12 h. On the other hand, mdr1a gene disruption did not change the contributions of renal and bile clearances to total clearance, the plasma protein binding, or the blood-to-plasma partition coefficient. Brain concentration-time profiles in mdr1a (+/+) and mdr1a (-/-) mice showed a different pattern from those in plasma and other tissues, indicating digoxin accumulation in the brain tissue. Because there was no difference in the uptake or release of digoxin by brain tissue slices from the two types of mice, we assumed the brain tissue compartment to consist of two parts (a well-stirred part with influx and efflux clearance and an accumulative part). Simulation with this model gave excellent agreement with observation when active efflux clearance across the blood-brain barrier was assumed to be zero in mdr1a (-/-) mice. The observations in other tissues in both types of mice were also well simulated.

Gamma-irradiation deregulates cell cycle control and apoptosis in nevoid basal cell carcinoma syndrome-derived cells

The nevoid basal cell carcinoma syndrome (NBCCS) is an autosomal dominant disorder characterized by nevi, palmar and plantar pits, falx calcification, vertebrate anomalies and basal cell carcinomas. It is well known in NBCCS that gamma-irradiation to the skin induces basal cell carcinomas or causes an enlargement of the tumor size, although the details of the mechanism remain unknown. We have established lymphoblastoid cell lines from three NBCCS patients, and we present here the first evidence of abnormal cell cycle and apoptosis regulations. A novel mutation (single nucleotide deletion) in the coding region of the human patched gene, PTCH, was identified in two sibling patients, but no apparent abnormalities were detected in the gene of the remaining patient. Nevertheless, the three established cell lines showed similar features in the following analyses. Flow cytometric analyses revealed that the NBCCS-derived cells were accumulated in the G2M phase after gamma-irradiation, whereas normal cells showed cell cycle arrest both in the G0G1 and G2M phases. The fraction of apoptotic cells after gamma-irradiation was smaller in the NBCCS cells. The level of p27 expression markedly decreased after gamma-irradiation in the NBCCS cells, although the effects of the irradiation on the expression profiles for p53, p21 and Rb did not differ in normal and NBCCS cells. These findings may provide a clue to the molecular mechanisms of tumorigenesis in NBCCS.

Acidic glycosaminoglycans of abdominal mucin in a case of pseudomyxoma peritonei caused by appendiceal cancer

Although the use of intraperitoneal mucolytic agents is useful in the management of pseudomyxoma peritonei, effective removal of mucin is difficult even by repeated mucolysis in cases with massive ascites. To establish mucolytic therapy as a further effective procedure, biochemical analysis of mucin is required in greater detail. We reported here a case of pseudomyxoma peritonei caused by primary appendiceal cancer with biochemical analysis of mucin. The abdominal cavity in this case was filled with massive mucinous ascites. Although the mucolytic therapy was performed repeatedly, it was not effective in preventing mechanical ileus which was followed by surgical exclusion. Biochemical study of mucin showed that the mucin contained a small amount of hyaluronic acid, as characterized by electrophoretic study. These data led us to the hypothesis that the hyaluronic acid component plays a role in the pathogenesis of the replacement of mucin in the abdominal cavity.

Clinical, pathological and mineralogical features in two autopsy cases of workers exposed to agalmatolite dust

An agalmatolite miner and processor showed large shadows at the bilateral hila accompanied by surrounding emphysematous changes and irregular shadows on chest X-ray films. Chest CT scans were characterized by a mixture of tiny irregular structures and small round opacities. Histopathological examination revealed massive fibrosis, which corresponded to large shadows, but only a small number of typical silicotic nodules, indicating mixed dust pneumoconiosis. Mineralogical examination of the autopsy lungs showed quartz, pyrophyllite, mica, and kaolinite. Quartz accounted for 70% of the amount of all mineral dust in both patients, but pyrophyllite accounted for 10.8% and 14.4%. The pulmonary mineral dust composition in the two patients was well consistent with the mineral composition of the raw clays in the agalmatolite mine. In the two patients, chest X-ray findings and histopathological findings of the lungs also suggested agalmatolite pneumoconiosis, which was confirmed by mineral analysis of the lungs.

Sensitivity of foetal magnetocardiograms versus gestation week

Foetal magnetocardiograms (FMCGs) were measured using a nine-channel SQUID system equipped with first-order gradiometers (60 mm baseline, 20 mm diameter). The system was installed in a magnetically shielded room in a hospital. The white noise level was less than 10 fT/square root of Hz, and FMCGs above 1 pT were detected. These results and the depth to the foetal heart were used to estimate the current dipole. The relationship between the current dipole (Q) and the gestation week (G) was calculated and the average performance was determined as Q = 18G - 295. By using the estimated foetal current dipole, the measurement limit (average value) between depth and gestation weeks was determined. When the depth from the pickup coil to the foetal heart is 50, 60, 70 and 80 mm, the first detectable gestation weeks of FMCGs above 1 pT measured by a first-order gradiometer with 60 mm baseline were determined at 21, 23, 26, and 30 weeks respectively, and the detectable gestation weeks in the case of a 30 mm baseline were determined at 22, 26, 30 and 36 weeks respectively.

Overexpression of Bcl-2 protects human hepatoma cells from Fas-antibody-mediated apoptosis

BACKGROUND/AIMS

Fas is a cell surface antigen, that triggers apoptosis upon specific ligand or antibody binding. The proto-oncogene bcl-2 prevents apoptosis induced by various treatments. The aim of our study was to evaluate whether Bcl-2 protects hepatoma cells from Fas-mediated apoptosis.

METHODS

Two human cell lines, HCC-T and HepG2 were used. Expression of Fas antigen and Bcl-2 was detected by flow cytometry and Western blotting. Cell viability and apoptotic change were examined after anti-Fas- and antisense oligodeoxynucleotide treatments. Apoptotic cells were detected by nick-end labelling and the TUNEL method. To test if Bcl-2 expression can protect HepG2 cells from Fas-mediated apoptosis, the cells were transduced using retroviral vector, LZBC, designed to coexpress E. coli beta-galactosidase and human Bcl-2. To further confirm the protective effect of Bcl-2 expression against Fas-mediated apoptosis in HepG2, Bcl-2 expressing plasmid vector was produced and a cell line stably expressing Bcl-2 was cloned.

RESULTS

Western blot analysis showed constitutive Bcl-2 expression in HCC-T cells, but not in HepG2 cells. HCC-T was resistant to apoptosis after treatment with an agonist anti-Fas antibody (1 microg/ml for 3 days), whereas 33% of the HepG2 cells were killed by this treatment. Inhibition of Bcl-2 expression by transfection of antisense oligodeoxynucleotides caused spontaneous apoptosis in HCC-T, but not in HepG2 cells, suggesting that Bcl-2 is essential for survival of HCC-T cells, whereas other proteins may substitute for it in HepG2 cells. Following LZBC infection, 10% HepG2 cells were beta-galactosidase-positive by X-gal staining and Bcl-2-positive. In cells surviving after anti-Fas treatment, the proportion of beta-galactosidase-positive cells increased to 50% and the beta-galactosidase activity increased 6-fold, indicating that Bcl-2 expression protected the cells from Fas-mediated apoptosis. In the cloned HepG2 cells stably expressing Bcl-2, the extent of Fas-mediated apoptosis was inversely related to the level of Bcl-2 expression.

CONCLUSION

Bcl-2 confers protection to human hepatoma cells against Fas-mediated apoptosis, and is essential for survival of some, but not all, hepatoma cells.

[Anesthetic management for carotid and coronary artery surgery--concomitant versus two stage operation]

We reviewed the anesthetic management of 16 patients with concomitant severe coronary and carotid artery diseases. Eight patients underwent concomitant operations of coronary artery bypass graft and carotid endarterectomy, while the other 8 patients underwent two stage operation. Candidates for concomitant operations had unstable angina or serious coronary disease such as three vessel disease or severe stenosis of LMT. In comparison, most of patients undergoing two stage operation had symptomatic or occlusive carotid disease. In all cases, anesthesia was maintained with fentanyl and midazolam and the perfusion pressure during cardiopulmonary bypass was maintained above 70 mmHg. Some patients received thiopental or propofol for brain protection. The concomitant operations required much more transfusion and longer operation time than two stage operation. In addition, several cases of the concomitant operation needed intra-aortic balloon pumping or high dose of catecholamines. Indications for concomitant operation or two stage operation have to be determined through discussion among anesthesiologist, neurovascular as well as cardiovascular surgeons.

[Anesthetic management of patients undergoing implantation of left ventricular assist system]

We examined the anesthetic management of six patients with end-stage dilated and hypertrophic cardiomyopathy for implantation of left ventricular assist system. Although anesthesia was induced only with fentanyl or with combination of fentanyl and diazepam, hemodynamic changes after the anesthetic induction were variable and preoperative evaluation of left ventricular ejection fraction did not predict the hemodynamic changes. After the weaning from cardiopulmonary bypass, the right ventricular support by catecholamines, such as dopamine and dobutamine, and phosphodiesterase III inhibitors, such as amrinone, and pulmonary vasodilation by inhalation of nitric oxide were useful to maintain volume loading to the left ventricular assist system.

Dentatorubral-pallidoluysian atrophy protein interacts through a proline-rich region near polyglutamine with the SH3 domain of an insulin receptor tyrosine kinase substrate

Dentatorubral-pallidoluysian atrophy (DRPLA) is an autosomal dominant neuro degrees enerative disorder associated with CAG/glutamine repeat expansion. While the DRPLA gene is ubiquitously expressed, neuron death occurs in specific anatomical areas of the brain. This predicts that the DRPLA protein interacts with other proteins and that these interactions may play a role in pathogenesis. Here, we describe a protein that binds to the DRPLA product. One of the clones isolated with a yeast two-hybrid system was identified as a human homolog of the insulin receptor tyrosine kinase substrate protein of 53 kDa (IRSp53). The gene produced two mRNA forms by differential splicing and encoded 552 and 521 amino acids, respectively. The longer form was mainly expressed in the brain and the shorter one in other tissues. The products were phosphorylated upon stimulation of cultured cells with insulin or insulin-like growth factor 1. Binding of the DRPLA protein to IRSp53 was ascertained by co-immunoprecipitation with antibodies and also by co-localization in perinuclear oval dots in cells expressing engineered constructs. A proline-rich region near the polyglutamine tract of the DRPLA protein and the SH3 domain of IRSp53 were involved in the binding. An extended polyglutamine tract significantly reduced binding ability in yeast cells, but not in in vitro binding assays. The identification of IRSp53 and other proteins detected by the yeast hybrid system predicts that DRPLA functions in a signal transduction pathway coupled with insulin/IGF-1.

Retrospective analysis of effect of low-dose aprotinin priming on allogeneic blood transfusion in repeated cardiac operations

The objective of this retrospective study was to investigate efficacy of low-dose aprotinin priming therapy on the requirement of allogeneic transfusion and to identify risk factors for allogeneic transfusion in patients undergoing repeated cardiac operations. The present study includes a critical review of 124 consecutive charts of patients undergoing elective repeat cardiac surgery. We examined the effect of low-dose aprotinin priming therapy on blood loss, amounts of mediastinal drainage following intensive care unit (ICU) administration and the number of units of blood products given during the perioperative period. The rate of nonallogeneic transfusion was not affected by low-dose aprotinin priming therapy, although aprotinin reduced the amount of allogeneic transfusion and the amount of mediastinal drainage 12 h following ICU admission. In conclusion, low-dose aprotinin priming therapy is effective in reducing blood loss and the amount of allogeneic transfusion. However, it failed to improve the rate of cardiac reoperations without allogeneic blood transfusion.

Expression of extended polyglutamine sequentially activates initiator and effector caspases

To date, eight neurodegenerative disorders, including Huntington's disease and dentatorubral-pallidoluysian atrophy, have been identified to be caused by expansion of a CAG repeat coding for a polyglutamine (polyQ) stretch. It is, however, unclear how polyQ expansion mediates neuronal cell death observed in these disorders. Here, we have established a tetracycline-regulated expression system producing 19 and 56 repeats of glutamine fused with green fluorescent protein. Induced expression of the 56 polyQ, but not of the 19 polyQ stretch caused marked nuclear aggregation and apoptotic morphological changes of the nucleus. In vitro enzyme assays and Western blotting showed that polyQ56 expression sequentially activated initiator and effector caspases, such as caspase-8 or -9, and caspase-3, respectively. Furthermore, using cell-permeable fluorogenic substrate, the activation of caspase-3-like proteases was demonstrated in intact cells with aggregated polyQ. This is the first direct evidence that the expression of extended polyQ activates caspases and together with the previous findings that some of the products of genes responsible for CAG repeat diseases are substrates of caspase-3 indicates an important role of caspases in the pathogenesis of these diseases.

Successful treatment of rapidly progressive lupus nephritis associated with anti-MPO antibodies by intravenous immunoglobulins

We report a case of systemic lupus erythematosus (SLE) associated with crescentic glomerulonephritis and myeloperoxidase-specific anti-neutrophil cytoplasmic antibodies (MPO-ANCA). A 34-year-old Japanese female patient diagnosed with SLE developed rapidly progressive renal failure and nephrotic syndrome. Haemodialysis was required to restore renal function. Methylprednisolone pulse therapy followed by plasmapheresis did not suppress the progression of renal failure, so she was treated with high-dose intravenous immunoglobulin (IV-IG) therapy, which was well tolerated and effectively prevented renal failure. A renal biopsy showed diffuse proliferative lupus nephritis (WHO classification IVc) with predominant crescent formation and scant subendothelial immune deposits. These findings indicate that, in addition to lupus nephritis, which usually results from the deposition of circulating or locally formed immune complexes, MPO-ANCA may be involved in the pathogenesis of crescentic glomerulonephritis. Furthermore, we propose that IV-IG is an effective therapy for MPO-ANCA-related renal crisis in lupus nephritis.

Evidence that the cannabinoid CB1 receptor is a 2-arachidonoylglycerol receptor. Structure-activity relationship of 2-arachidonoylglycerol, ether-linked analogues, and related compounds

An endogenous cannabimimetic molecule, 2-arachidonoylglycerol, induces a rapid, transient increase in intracellular free Ca2+ concentrations in NG108-15 cells through a cannabinoid CB1 receptor-dependent mechanism. We examined the activities of 24 relevant compounds (2-arachidonoylglycerol, its structural analogues, and several synthetic cannabinoids). We found that 2-arachidonoylglycerol is the most potent compound examined so far: its activity was detectable from as low as 0.3 nM, and the maximal response induced by 2-arachidonoylglycerol exceeded the responses induced by others. Activities of HU-210 and CP55940, potent cannabinoid receptor agonists, were also detectable from as low as 0.3 nM, whereas the maximal responses induced by these compounds were low compared with 2-arachidonoylglycerol. Anandamide was also found to act as a partial agonist in this assay system. We confirmed that free arachidonic acid failed to elicit a response. Furthermore, we found that a metabolically stable ether-linked analogue of 2-arachidonoylglycerol possesses appreciable agonistic activity, although its activity was apparently lower than that of 2-arachidonoylglycerol. We also confirmed that pretreating cells with various cannabinoid receptor agonists nullified the response induced by 2-arachidonoylglycerol, whereas pretreating cells with other neurotransmitters or neuromodulators did not affect the response. These results strongly suggested that the cannabinoid CB1 receptor is originally a 2-arachidonoylglycerol receptor, and 2-arachidonoylglycerol is the intrinsic physiological ligand for the cannabinoid CB1 receptor.

Isolation of azo-dye-degrading microorganisms and their application to white discharge printing of fabric

Three bacterial strains, which degraded azo dyes, were isolated from soil and sewage samples. The strains were identified as Bacillus sp. OY1-2, Xanthomonas sp. NR25-2 and Pseudomonas sp. PR41-1. The bacteria produced azo-dyes-degrading enzymes. That catalyzed the reduction of methyl red and produced dimethyl p-phenylenediamine and o-aminobenzoic acid. The enzymes could thus be applied to white discharge printing of azo-dyed fabric by owing to there.

Expression of mRNAs encoding hormone receptors in the endolymphatic sac of the rat

The endolymphatic sac (ES) is believed to absorb the endolymphatic fluid produced by the stria vascularis and vestibular dark cells. Recent studies have implied that the function of the ES may be controlled by circulating hormones, suggesting that hormone receptors should exist there. In the present study, the expression of genes encoding receptors for aldosterone, atrial natriuretic peptide (ANP) and vasopressin in the ES was examined by reverse transcription-polymerase chain reaction (RT-PCR). Next, the cellular localization of the expression of these genes was investigated by in situ hybridization. RT-PCR indicated that aldosterone. ANP-A and vasopressin V1a receptor genes were expressed in the ES. In contrast, neither ANP-B nor vasopressin V2 receptor gene expression was detected. In situ hybridization experiments demonstrated aldosterone receptor gene expression in epithelial cells of the intermediate potion of the ES, while expression of ANP-A or V1a receptor genes was not detected. The present results suggested that aldosterone may play a specific role in the function of the ES. However, we could not conclude that ANP and vasopressin play physiological roles in the ES because receptors for these hormones were detected only by highly sensitive PCR.

Evaluation of platelet function by Sonoclot analysis compared with other hemostatic variables in cardiac surgery

Platelet function can be easily measured as time to peak (TP) by Sonoclot Coagulation & Platelet Function Analyzer (Sienco Inc., Morrison, CO) analysis. However a correlation between Sonoclot analysis and platelet aggregation, which is accepted as a test of platelet function, has not been established. In this study, we compared TP and collagen-induced whole blood platelet aggregation in 15 patients undergoing cardiac surgery. Two or three blood samples were randomly obtained from each patient before and after cardiopulmonary bypass (CPB). Sonoclot analysis, collagen-induced whole blood aggregation, and laboratory measurement (including platelet count and coagulation profile) were measured. Seventy-two samples were obtained (35 before CPB and 37 after CPB). TP was correlated with collagen-induced whole blood aggregation (r = -0.652), platelet count (r = -0.671), fibrinogen level (r = -0.598), prothrombin time (r = 0.394), activated partial thromboplastin time (r = 0.486), and use of CPB (r = 0.380). Significant predictors of TP for multiple linear regression modeling were collagen-induced whole blood aggregation, platelet count, and fibrinogen level (r = 0.742). In conclusion, Sonoclot analysis TP predicts approximate platelet function in patients undergoing cardiac surgery.

IMPLICATIONS

Approximate platelet function can be easily measured as time to peak by Sonoclot analysis. In this study, time to peak was predicted by platelet count, whole blood platelet aggregation, and fibrinogen level for multiple linear regression modeling.

Investigation of glucocorticoid-induced apoptotic pathway: processing of caspase-6 but not caspase-3

Glucocorticoids (GCs) are essential therapeutic reagents for the treatment of lymphomas and leukemias. GCs cause cell death in certain types of lymphoid cells mediated by the process known as apoptosis. This cell death is completely inhibited by Bcl-2. Here we report that Bcl-2 and benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethylketone (zVAD-fmk), a broad spectrum caspase inhibitor, prevent loss of mitochondrial membrane potential (delta psi m) and the production of reactive oxygen species (ROS) caused by GC, while acetyl-Asp-Glu-Val-Asp-aldehyde (Ac-DEVD-CHO), an inhibitor of the caspase-3 family proteases, does not. This suggests that the inhibition by Bcl-2 and activation of some initiator caspases are upstream events of mitochondrial damage, whereas the activation of caspase-3 family proteases occurs downstream of mitochondrial changes. We also demonstrate that caspase-6 but not caspase-3 is cleaved and activated during GC-mediated apoptosis and that poly(ADP-ribose) polymerase (PARP), a substrate of caspases, also undergoes proteolysis. In addition, we provide the evidence that DNA fragmentation is markedly inhibited by Ac-DEVD-CHO, while cell death, assessed by the damage of the plasma membrane, is marginally inhibited or merely delayed.

[Immunoglobulin production by human peripheral B cells against Staphylococcus aureus]

Immunoglobulin (Ig) production by human B cells in thymus-independent (TI) and -dependent (TD) immune response against Staphylococcus aureus was investigated in vitro. Highly purified human peripheral B cells were cultured either in the presence of formalinized Cowan I strain Staphylococcus aureus (SAC) or with anti-CD3 stimulated T cells, and Ig content in supernatants was analyzed after 10 days of culture by specific sandwich ELISA. When activated with SAC in the absence of T cells, B cells produced minimal amounts of Ig. In the presence of interleukin-2 (IL-2) or supplemental recombinant CD40 ligand plus IL-2, Ig production by SAC-induced B cells was dramatically enhanced. When cultured with T cells stimulated with low concentrations of anti-CD3 or when cultured with smaller numbers of T cells, B cells produced large amounts of Ig, whereas T cells stimulated with higher concentrations of anti-CD3 or large numbers of T cells failed to induce effective Ig secretion by B cells. These findings suggest that TI immune response against Staphylococcus aureus is strongly enhanced in the presence of activated T cells in an antigen non-specific manner, indicating its critical role in the local humoral immune defense. Moreover, it is indicated that the secretion of Ig induced by TD antigens participates in the immune defense against Staphyloccocus aureus dependent on activated T cell/B cell ratio or an impact of CD3 stimulation on T cells.

[Recurrent pneumomediastinum in the course of interstitial pneumonia associated with dermatomyositis]

A 59-year-old woman with dermatomyositis suffered pneumomediastinum twice during steroid therapy for aggravated myositis. In both instances, pneumomediastinum occurred when the patient's aggravated myositis was in remission. Plain chest X-ray films showed a slit-like air lucency around the left pulmonary artery. This indicated that air entered the mediastinum through the left hilum. Although pneumomediastinum associated with dermatomyositis is considered to be fatal, in our patient each instance of pneumomediastinum spontaneously disappeared very quickly. The favorable course of our patient seemed to be associated with her high elevated levels of serum creatine kinase and seropositive results for anti-Jo-1 antibody.

Nuclear translocation and increased expression of Bax and disturbance in cell cycle progression without prominent apoptosis induced by hyperthermia

Effects of hyperthermia at 42.5 degreesC for 6 h on cell survival, cell cycle progression, and the localization and expression levels of Bcl-2 and Bax, as well as the association between Bcl-2 and Bax in human lung cancer cells were investigated. Untreated human lung cancer cells, though immortalized, expressed Bax unlike peripheral lymphocytes with low Bax expression. Bcl-2 was localized only in the cytoplasm in all the cell lines tested, whereas Bax was localized in the cytoplasm and/or nucleus; (1) only in the nucleus in three cell lines, (2) either in the nucleus or the cytoplasm in three cell lines, (3) in both the nucleus and the cytoplasm in one cell line, and (4) only in the cytoplasm in three cell lines. Of 10 cell lines examined, 6 had a low sensitivity to hyperthermia with a viability of 50% or more, and four cell lines had a high sensitivity to hyperthermia with a viability of less than 50% regardless of cell type. In cell lines highly sensitive to hyperthermia, Bax was localized in the nucleus. Hyperthermia increased the cellular level of Bax, but not Bcl-2, and reduced the association between Bcl-2 and Bax expression in PC-10 cells. Although the Bax level increased, hyperthermia induced only mild apoptosis and caused prominent cell cycle disturbance, especially in the S and G2M phases. Thus, hyperthermia at 42.5 degreesC for 6 h had cytostatic effect as well as caused mild apoptosis. Interestingly, during 3 h of hyperthermia, Bax translocated from the cytoplasm to the nucleus, whereas Bcl-2 remained in the cytoplasm. These results raise the possibility that Bax may lose its function as the inducer of apoptosis by translocating into the nucleus or have an unknown role in the nucleus.

Prolactin-regulated apoptosis of Nb2 lymphoma cells: pim-1, bcl-2, and bax expression

Lactogen-dependent Nb2 lymphoma cells, widely employed for studying prolactin (PRL) mitogenic mechanisms, are also useful for investigations of apoptosis in T-lineage lymphocytes. Utilizing PRL-dependent Nb2-11 cultures, apoptosis-regulatory genes were evaluated for participation in dexamethasone- (DEX) provoked cell death or its inhibition by PRL. Treatment of lactogen-starved, G1-arrested Nb2-11 cells with DEX (100 nM) activated apoptosis within 12 h evaluated by flow cytometric analysis of fragmented DNA. This effect was not associated with altered expression of bcl-2, bax, or pim-1. PRL (10 ng/mL), coincubated with DEX-treated cells, completely blocked DEX-induced apoptosis. This inhibition was associated with increased expression of bcl-2 and pim-1 mRNAs, genes reported to suppress apoptosis, within 2-6 h after addition of the hormone. Moreover, the increased transcription of bcl-2 and pim-1 was coupled to increases in their protein levels. The results suggest that bcl-2, bax, and pim-1 do not play a critical role in DEX-induced apoptosis in Nb2 cells. However, expression of bcl-2, together with pim-1, may have a role in mediating the antiapoptotic actions of PRL.

Intracellular aggregate formation of dentatorubral-pallidoluysian atrophy (DRPLA) protein with the extended polyglutamine

Dentatorubral-pallidoluysian atrophy (DRPLA) is an autosomal dominant neurodegenerative disorder caused by the abnormal CAG triplet-repeat expansion resulting in an elongated polyglutamine (polyQ) stretch. We have recently showed that the DRPLA protein is cleaved during apoptosis by caspase-3, one of the cysteine protease family members known to be activated during apoptosis. We report here the subcellular localization of the DRPLA protein by fusing the green fluorescent protein as a tag. The full length DRPLA protein is localized predominantly but not exclusively in the nucleus regardless of the length of the polyQ stretch. In contrast, an N-terminal-deleted fragment containing polyQ produced by the proteolytic cleavage with caspase-3 is found both in the nucleus and the cytoplasm. Moreover, the same fragment with the elongated polyQ showed aggregation when overexpressed. Some cells with aggregate formation showed apoptotic phenotype. These findings raise the possibility that the DRPLA protein processed by caspase-3 may lead to aggregation of the protein resulting in the development of neurodegeneration.

Isolation of a cDNA for a novel 120-kDa GTP-binding protein expressed in motor neurons in the salmon brain

We isolated a cDNA encoding a novel protein with GTP-binding motifs from the salmon brain. The cloned 5.5-kb cDNA encoded 971 amino acids, which showed limited homology with members of large GTP-binding proteins, such as dynamin, MX protein and VPS1. By in vitro translation analysis, the size of the encoded protein was estimated to be 120 kDa. The recombinant protein including the putative GTP-binding domain was shown to bind to GTP in vitro. mRNA was strongly expressed in the brain, ovary and skeletal muscle. In the brain, expression of the mRNA was observed specifically in motor neurons, in nucleus oculomotorius, in nucleus valvulae lateralis, in the medulla oblongata and in the spinal cord. To determine the cell biological significance of the encoded protein, we transfected CHO cells with wild type or a putative constitutive active mutant of the mG120 (120-kDa G protein expressed in motor neurons) and examined morphological changes. However, no clear changes were observed. The functional role of this novel motor neuron-specific large GTP-binding protein remains to be elucidated.