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H Endou

Publications and source records attributed to H Endou.

At least 91 records · Page 5Linked to original sources
PubMed1997

Cisplatin-induced apoptosis of immortalized mouse proximal tubule cells is mediated by interleukin-1 beta converting enzyme (ICE) family of proteases but inhibited by overexpression of Bcl-2.

Cisplatin is known to induce serious renal damage including acute renal failure, the major site of renal injury appears to be localized to the third segment of the proximal tubule (S3). Apoptosis occurs during a variety of acute injuries to tubule cell. The purpose of this study was to determine whether cisplatin induces apoptosis of immortalized mouse S3 cells, and to define the intracellular pathways leading to cell death. S3 cells exposed to cisplatin exhibited biochemical, morphological, and flow cytometric changes characteristic of apoptosis associated with slight necrosis. Cisplatin-induced apoptosis could be inhibited by overexpression of crmA, a cowpox virus gene, of which the product is known to suppress activities of the interleukin-1 beta converting enzyme (ICE) family proteases. On the other hand, overexpression of bcl-2, an antiapoptotic oncogene, rendered S3 cells partially resistant to cisplatin. These results indicate that cisplatin-induced proximal tubule damage is associated with apoptosis, which is positively modulated by the ICE family of proteases and negatively by the product of bcl-2.

Animals↗
PubMed1997

An adenosine deaminase inhibitor prevents puromycin aminonucleoside nephrotoxicity.

Puromycin aminonucleoside (PAN) toxicity was totally inhibited in the rat in vivo and in cultured glomerular epithelial cells (GECs) in vitro using the adenosine deaminase (ADA) inhibitor, 2'-deoxycoformycin (DCF). DCF completely inhibited ADA activity in glomeruli and protected against the development of PAN nephrosis; the 24-h urinary protein excretion of treated rats compared with controls (PAN rats) 9 days after PAN injection was 16 +/- 2 mg and 524 +/- 55 mg, respectively (p < .01). Morphological examination also demonstrated that the glomerular epithelial cells were protected against PAN-induced damage. Furthermore, when DCF was added to the first passage of GECs simultaneously with PAN, the adenosine triphosphate contents of remnant GECs on culture substrata increased in a dose-dependent manner, and PA toxicity was completely inhibited by 10(-4) M DCF. The order of ADA activity in glomeruli from various species was as follows: rat > monkey > guinea pig > dog > rabbit > mouse. High activity of ADA in the glomerulus was limited to species in which PAN induced nephrosis. Additionally, DCF increased glomerular cyclic AMP contents, resulting from enhanced adenosine accumulation in the pericellular space. These results indicate that the pathogenesis of PAN toxicity is closely related to adenosine metabolism and that ADA plays a key role in this model. Furthermore, we speculate that DCF contributes to the inhibition of reactive oxygen metabolites by decreasing the substrate of xanthine oxidase and/or increasing pericellular adenosine accumulation.

Adenosine↗
PubMed1997

Thromboxane A2 mediates cisplatin-induced apoptosis of renal tubule cells.

The purpose of this study was to elucidate the role of thromboxane A2 (TXA2) in cisplatin-induced apoptosis of mouse renal cells derived from the terminal proximal tubule (S3). RT-PCR analysis revealed that S3 cells express TXA2 receptor mRNA. A TXA2 receptor antagonist, KW-3635, dose-dependently inhibited cisplatin-induced apoptosis of S3 cells. Treatment of S3 cells with a TXA2 agonist, STA2, induced a significant decrease in their viability and resulted in the characteristic ladder pattern resulting from intranucleosomal DNA cleavage. Treatment with KW-3635 resulted in attenuation of the increase in c-fos mRNA expression level in cisplatin-treated S3 cells. In conclusion, TXA2 appears to mediate cisplatin-induced apoptosis of S3 cells by inducing an increase in the level of c-fos mRNA expression.

Animals↗
PubMed1997

Attenuation of renomedullary phospholipase C isozyme, PLC-delta 1, in spontaneously hypertensive rats.

The distributional patterns of PLC isozymes within the kidney were investigated using spontaneously hypertensive rats (SHRs) and normotensive Wistar-Kyoto (WKY) rats at 4 and 12 weeks of age. PLC-beta 1, PLC-beta 3 and PLC-delta 1 quantified by Western blot analysis, were present in the highest concentrations in the inner medulla of rats at both 4 and 12 weeks of age. On the other hand, PLC-beta 4, PLC-gamma 1 and PLC-gamma 2 were distributed almost equally among the regions for the rats of both ages. When compared with WKY rats at 12 weeks of age, the amounts of PLC-beta 1, PLC-beta 3, PLC-gamma 1, PLC-gamma 2, and PLC-delta 1 in the inner medulla of SHRs were significantly lower, and the amount of PLC-delta 1 in the inner stripe of the outer medulla was also significantly lower. Even at the prehypertensive stage at 4 weeks of age, the inner medullary concentration of PLC-delta 1 was significantly lower in SHRs than WKY rats. These results suggest that PLC-delta 1 would play an important role in the development of hypertension.

Animals↗
PubMed1997

Negative strand of hepatitis C virus RNA in the liver of patients with chronic hepatitis C after interferon treatment.

In patients receiving interferon therapy for chronic hepatitis C, serum hepatitis C virus (HCV) RNA often reverts from an undetectable to a detectable form after completion of treatment. Detection of the negative strand of HCV-RNA in liver tissue is regarded as an index of viral proliferation. Therefore, we investigated changes in the hepatic negative-strand HCV-RNA following interferon therapy to determine whether this parameter could predict the long-term response to treatment. The subjects of this study were 27 patients with chronic active hepatitis C. Serum positive-strand and hepatic tissue negative-strand HCV-RNA were detected using polymerase chain reaction. At the completion of interferon treatment, serum HCV-RNA was not detected in 21 patients. One year following treatment it remained undetectable in 14 of these patients but it had reverted to a detectable form in seven. The 14 patients in whom hepatic negative-strand RNA was not detected between 2 weeks and 12 months after treatment, had not relapsed after another year. In the 13 remaining patients, negative-strand RNA was found in liver tissue and serum RNA either reverted to a detectable form or remained detectable throughout. From these findings, we conclude that the detection of negative-strand HCV-RNA in liver tissue 2 weeks after the completion of interferon therapy is useful for predicting the long-term effect of therapy.

Adult↗
PubMed1996

Cloning and functional characterization of a system ASC-like Na+-dependent neutral amino acid transporter.

A cDNA was isolated from mouse testis which encodes a Na+-dependent neutral amino acid transporter. The encoded protein, designated ASCT2, showed amino acid sequence similarity to the mammalian glutamate transporters (40-44% identity), Na+-dependent neutral amino acid transporter ASCT1 (57% identity; Arriza, J. L., Kavanaugh, M. P., Fairman, W. A., Wu, Y.-N., Murdoch, G. H., North, R. A., and Amara, S. G.(1993) J. Biol. Chem. 268, 15329-15332; Shafqat, S., Tamarappoo, B. K., Kilberg, M. S., Puranam, R. S., McNamara, J. O., Guadano-Ferraz, A., and Fremeau, T., Jr. (1993) J. Biol. Chem. 268, 15351-15355) and a mouse adipocyte differentiation-associated gene product AAAT (94% identity; Liao, K., and Lane, D.(1995) Biochem. Biophys. Res. Commun. 208, 1008-1015). When expressed in Xenopus laevis oocytes, ASCT2 exhibited Na+-dependent uptakes of neutral amino acids such as L-alanine, L-serine, L-threonine, L-cysteine, and L-glutamine at high affinity with Km values around 20 microM. L-Methionine, L-leucine, L-glycine, and L-valine were also transported by ASCT2 but with lower affinity. The substrate selectivity of ASCT2 was typical of amino acid transport system ASC, which prefers neutral amino acids without bulky or branched side chains. ASCT2 also transported L-glutamate at low affinity (Km = 1.6 mM). L-Glutamate transport was enhanced by lowering extracellular pH, suggesting that L-glutamate was transported as protonated form. In contrast to electrogenic transport of glutamate transporters and the other ASC isoform ASCT1, ASCT2-mediated amino acid transport was electroneutral. Na+ dependence of L-alanine uptake fits to the Michaelis-Menten equation, suggesting a single Na+ cotransported with one amino acid, which was distinct from glutamate transporters coupled to two Na+. Northern blot hybridization revealed that ASCT2 was mainly expressed in kidney, large intestine, lung, skeletal muscle, testis, and adipose tissue. Functional characterization of ASCT2 provided fruitful information on the properties of substrate binding sites and the mechanisms of transport of Na+-dependent neutral and acidic amino acid transporter family, which would facilitate the structure-function analyses based on the comparison of the primary structures of ASCT2 and the other members of the family.

Amino Acid Sequence↗
PubMed1996

Cisplatin-induced toxicity in immortalized renal cell lines established from transgenic mice harboring temperature sensitive SV40 large T-antigen gene.

We established renal cell lines from definite nephron segments which were microdissected from kidneys of transgenic C57BL/6 mice, harboring the large T-antigen gene of temperature-sensitive mutant simian virus 40, pSVtsA58(ori-). Cell culture was under a humidified atmosphere of 5% CO2 in air, on collagen-coated dishes, and in RITC80-7 medium with 5% fetal bovine serum, 10 micrograms/ml transferrin, 1 microgram/ml insulin, 10 ng/ml recombinant human EGF, penicillin and streptomycin. Cell line which kept contact inhibition character was established from each segment. Cells derived from distal tubule, cortical and outer medullary collecting duct possessed their cyclic AMP response to arginine-vasopressin, like their original nephron segment. On the other hand, cells derived from terminal proximal tubules (S3 segment) formed a cobblestone-like confluent monolayer, and did not respond to arginine-vasopressin like their fresh segments. Since cisplatin, a well-known nephrotoxic substance, damages proximal tubules (especially S3) rather than collecting ducts, we assayed cell number, protein content, and ATP content of cultured S3 cells at various times after addition of 0.2 mM cisplatin. Decrease of cell number, total protein content and total ATP content of culture cells occurred after 10 h incubation with 0.2 mM cisplatin. The 50% lethal dose (LD50) of cisplatin in S3 cells was 4 x 10(-5) M after 20 h incubation and 8.5 x 10(-6) M after 40 h incubation. Outer medullary collecting duct (OMCD) cells were damaged 30% maximally after 20 h incubation with cisplatin, and LD50 in them became 2.5 x 10(-5) M after 40 h incubation. We could show that the LD50 of cisplatin in the OMCD cell line was three times higher than that in the S3 cell line. Thus, these cell lines are the first in the kidney to definite the segmental origin and to maintain some differentiated unique functions. They are valuable for studies on intrarenal site-specific actions and possible mechanisms of action of pharmacological and toxic substances.

Animals↗
PubMed1996

Effect of adenosine on phorbol myristate acetate induced-reactive oxygen metabolite production in cultured mesangial cells.

Cultured rat mesangial cells produced chemiluminescence in response to phorbol myristate acetate. Because 90% of this chemiluminescence was suppressed by 10 mU/ml superoxide dismutase, reactive oxygen metabolites are most likely involved in the chemiluminescence reaction. To clarify the role of cyclic AMP in the regulation of reactive oxygen metabolites production in cultured mesangial cells, we studied the effects of adenosine, an adenosine analog (2-chloroadenosine), and forskolin on phorbol myristate acetate-induced chemiluminescence. Exogenous adenosine suppressed the production of reactive oxygen metabolites in a dose-dependent manner (maximum at 1 mM adenosine: 70.6 +/- 3.2% of control). Lower concentration of 2-chloroadenosine (maximum at 100 mu M 2-chloroadenosine: 63.2 +/- 2.1% of control) and forskolin (maximum at 200 mu M forskolin: 53.4 +/- 2.6% of control) also significantly suppressed the production of reactive oxygen metabolites. In addition, adenosine analogs increased intracellular cyclic AMP in a dose-dependent manner in the order: 5'-N-ethylcarboxamidoadenosine>2-chloroadenosine>N6-cyclohexyladenosine. These results are in accordance with the probability that exogenous adenosine, by increasing intracellular cyclic AMP via the A2 receptor, inhibits the production of reactive oxygen metabolites through direct protein kinase C activation induced by phorbol myristate acetate in cultured rat mesangial cells.

2-Chloroadenosine↗
PubMed1996

ATP-induced calcium mobilization in glomerular mesangial cells is mediated by P2U purinoceptor.

To identify the functional P2 purinoceptor subtype in glomerular mesangial cells (GMC), polymerase chain reaction coupled with reverse transcription (RT-PCR) were performed, and cytosolic free calcium concentration ([Ca2+]i) was determined. RT-PCR analysis revealed that the molecular identity of P2 purinoceptor localized to GMC was both P2U and P2Y. The rank order of potency in stimulating [Ca2+]i was ATP [symbol: see text] UTP > 2-methylthio-ATP > ADP [symbol: see text] adenosine [symbol: see text] AMP. In addition, cross-desensitization between ATP and UTP occurred. In conclusion, ATP induces increase in [Ca2+]i via P2U purinoceptor in GMC.

Adenosine Diphosphate↗
PubMed1996

[Drug-induced nephrotoxicity].

The incidence of drug-induced nephrotoxicity (DIN) has recently been increasing. Based on developments in molecular biology and cell biology, cultured cells have become a very useful tool for investigating DIN. Especially, the immortalized cell lines derived from well-defined nephron segments are ideal for such studies. As indicators to detect DIN, myosin light chain phosphorylation in glomerular mesangial cells, enzymes of proximal tubule origin such as glycine-amidinotransferase, cytosolic free calcium concentration and intracellular ATP content may be useful. The involvement of nitric oxide and heat shock protein in DIN has been reported. Therapeutic effects of growth factors such as HGF or EGF for DIN have been identified. The direct evidence for the involvement of reactive oxygen species and the molecular basis for redox regulation in DIN is required. Cisplatin has been shown to induce apoptosis, and the role of apoptosis in DIN remains to be further clarified. Thus, in parallel with in vivo studies, cultured cells provide an opportunity for clarifying the intracellular mechanism for DIN more precisely and establishing an efficient screening system to develop drugs to prevent DIN.

Amidinotransferases↗
PubMed1996

[The mechanisms of urate transport in the kidney and the intestine].

Most urate is secreted from the kidney, but the intestine can also secrete urate. In the kidney, urate is transported in the proximal tubule which shows marked species differences. In human and rat, net urate reabsorption is seen, whereas rabbit and pig show net secretion. The transport of urate in the proximal tubule is bidirectional, reabsorption in S1, secretion in S2, and postsecretory reabsorption in S3. Although the mechanisms of transcellular urate transport are not fully understood, the influx of urate into the proximal tubule cell should be carried out by urate/anion exchanger, and the efflux by potential driven pathway. In the intestine, purine compounds are strongly metabolized to urate, that is transported. When the kidney function is normal, urate is reabsorbed, but in renal insufficiency urate can be excreted from the intestine.

Aged↗
PubMed1995

Guanidinoacetic acid (GAA) synthesis in rat tubular suspension as a system for evaluating gentamicin (GM) nephrotoxicity.

Since guanidinoacetic acid (GAA), a precursor of creatine, is synthesized mainly in the proximal tubule of the kidney where gentamicin (GM) nephrotoxicity often occurs, GM-induced renal cell damage was investigated using GAA synthesis in tubular suspension as an indicator. Results obtained were as follows: (1) GAA synthesis was significantly suppressed with 1 mM GM; (2) GM-induced decrease in GAA synthesis was recognized during incubation longer than 15 min; (3) furosemide significantly enhanced the suppression of GAA synthesis by GM. The results obtained parallel with those in the whole animal thus making GAA synthesis in tubular suspension a valid system for evaluating the GM-induced proximal tubular damage.

Animals↗
PubMed1995

Effect of P2Y-purinoceptor stimulation on renal gluconeogenesis in rats.

In the freshly prepared rat renal cortical tubule suspension, the effects of ATP on intracellular free calcium mobilization and gluconeogenesis were investigated. ATP increased intracellular free calcium concentration ([Ca2+]i) in a dose-dependent manner (10(-6) - 10(-3) M). The rank order in the potency of ATP analogs at 10(-4) M was 2-methylthio ATP > ATP > or = ADP. AMP, adenosine and alpha, beta-methylene ATP did not respond to [Ca2+]i. These results suggest that P2-purinoceptor in the rat kidney cortex should be specifically P2Y subtype. Renal gluconeogenesis from pyruvate was stimulated maximally by 10(-4) M ATP (48.3 +/- 13.2%). This effect was significantly inhibited by 10(-4) M suramin. Thus, the present study suggests that renal gluconeogenesis is increased via P2Y-specific purinoceptor stimulation.

Adenine Nucleotides↗
PubMed1995

Establishment of vasopressin-responsive early proximal tubular cell lines derived from transgenic mice harboring temperature-sensitive simian virus 40 large T-antigen gene.

A little is known about vasopressin receptor in early proximal tubule (S1). The purpose of this study is to establish the vasopressin-responsive S1 cell line derived from transgenic mice harboring temperature-sensitive(ts) simian virus (SV) 40 large T-antigen gene. The cells showed a temperature-sensitive cell growth characteristic of encoding tsSV40. The S1 cells retained a unique morphology specific to proximal tubule. The cells showed the vasopressin-induced increase in intracellular calcium concentration ([Ca2+]i) mediated by both V1a and the putative Vp receptor. Of nineteen clonal cell lines established from the parental cells, three expressed only V1a receptor, and five retained both V1a and Vp receptor. In conclusion, these immortalized S1 cell lines may be useful for studying vasopressin receptor subtypes in S1.

Animals↗