[Show abstract][Hide abstract] ABSTRACT: Aristolochic acid (AA) is considered to be a causative agent for progressive interstitial renal fibrosis, leading to AA nephropathy. Lysophosphatidic acid (LPA) is a mediator in the onset of renal fibrosis. In this study, we analyzed the molecular species of LPA and its precursor lysophospholipids in kidney tissue from rats exposed to AA. Daily intraperitoneal injections of AA for 35 days to rats gave rise to fibrosis in kidney, decreased the kidney levels of LPA, lysophosphatidylserine and lysophosphatidylinositol. In rat renal cell lines (NRK52E and NRK49F), AA-induced cytotoxicity was potentiated by Ki16425, LPA1, 3 receptor antagonist. The level of mRNA encording α-smooth muscle actin was significantly increased by AA-treatment only in NRK52E cells, while the mRNA level of collagen III was decreased in both NRK52E and NRK49F cells. These results suggest that endogenous LPA in rat kidney prevents AA-induced renal fibrosis.
[Show abstract][Hide abstract] ABSTRACT: Cadmium is a hazardous metal whose chronic exposure induces renal failure due to fibrosis, but the mechanisms are not well known. In this study we analyzed the molecular species of lysophosphatidic acid (LPA) and related phospholipids, together with their metabolic enzyme activity, in plasma from Wistar rats exposed up to 300 ppm Cd(2+) in drinking water for 114 days. Exposure of 300 ppm Cd(2+) for 114 days enhanced autotoxin (ATX)/lysophospholipase D activity, but significantly lowered the total levels of LPA, and lysophosphatidylethanolamine. Interestingly, the total level of sphingosine-1-phosphate (S1P) was elevated dose-dependently by Cd(2+). Cultured rat kidney-derived interstitial fibroblast cells, NRK49F cells and proximal epithelial cells, NRK52E cells, were both responsive to the protective action of LPA or S1P against Cd(2+) toxicity. The former cell expresses ATX RNA. In conclusion, the elevation of LPA-producing enzyme activity and S1P concentrations in plasma after exposure of rats to Cd(2+) would protect from the renal toxicity of Cd(2+).
No preview · Article · Dec 2013 · Food and chemical toxicology: an international journal published for the British Industrial Biological Research Association
[Show abstract][Hide abstract] ABSTRACT: We previously found that lysophosphatidic acid (LPA)-like activity eliciting Cl(-) currents in Xenopus oocytes is increased in rabbit aqueous humor (AH) following corneal freeze wounds. The purpose of this study was to examine whether actual levels of LPA in AH from wounded eyes are higher than those from control eyes, and to determine the sources and enzymatic pathways of AH LPA in control and wounded conditions. Lysophospholipase D (lysoPLD) activity was measured by the enzymatic determination of choline following incubation of AH samples with exogenous lysophosphatidylcholines (LPCs). The molecular species compositions of LPA and LPC in fresh and incubated AH were determined by liquid chromatography-tandem mass spectrometry. A high, but similar activity of lysoPLD in the samples from both control and freeze-wounded eyes was detected. Its enzymatic properties resemble those of plasma lysoPLD, identified as autotaxin. Levels of LPCs, predominant substrates of lysoPLD in AH, were several times higher in the AH samples from injured eyes than those from the control eyes. Our results suggest that lysoPLD is constitutively released from corneal tissues and/or ciliary body into the AH, with no injury-induced increase in release following freeze-wounding. They also suggest that wound-induced increases in LPA-like biological activity are due to linoleoyl species-rich molecular composition in AH from wounded eyes. A possible mechanism of the altered molecular composition is an increase in the AH concentrations of LPCs, linoleoyl species of which are preferentially converted to corresponding unsaturated LPA by the constitutively active lysoPLD.
No preview · Article · Jan 2012 · Prostaglandins & other lipid mediators
[Show abstract][Hide abstract] ABSTRACT: Although lysophospholipids have attracted much attention due to their diverse physiological activities through their specific receptors, little is known about their metabolic fates in mammalian digestive systems after their ingestion as a minor food component. In this study, we analyzed five lysophospholipids in lipid extracts of a standard rat chow and feces of rats fed the chow by two-dimensional thin layer chromatography and liquid chromatography-tandem mass spectrometry. The most abundant lysophospholipid in the rat chow was lysophosphatidylcholine followed by lysophosphatidylethanolamine, lysophosphatidic acid (LPA), lysophosphatidylinositol and lysophosphatidylserine (LPS) in an increasing order, but their concentrations were very low in rat feces. Among the molecular species of LPS in the chow, only saturated species were detected in the feces in significant amounts. In addition, several molecular species of LPA remained in the feces in variable portions (saturated > monounsaturated > polyunsaturated). These results suggest that a portion of ingested LPA and LPS reach the rat large intestine, affecting physiological colon functions.
No preview · Article · Jun 2011 · Journal of Agricultural and Food Chemistry
[Show abstract][Hide abstract] ABSTRACT: Abnormal production of lysophosphatidic acid (LPA), an important lysophospholipid mediator, in the kidney was examined to participate in the pathogenesis of renal fibrosis in rats. The secretory lysophospholipase D activity of autotoxin was considered as a possible pathway for extracellular production of LPA in the pathological renal fluids.
In this study of rats with unilateral ureteral obstruction for two weeks, we measured concentrations of LPA and its precursor, lysophosphatidylcholine stored in the urinary bladder and present in the swollen pelvis of the ligated kidney as well as the corresponding blood plasma by liquid chromatography-tandem mass spectrometry.
We found that concentrations of LPA and lysophosphatidylcholine accumulated in the effluent in the swollen pelvis of the ligated kidney of unilateral ureteral obstruction rats were much higher than those in the urinary bladder. The molecular species composition of LPA in the former was considerably different from that in the blood plasma, indicating the involvement of an additional source other than the blood circulation supplying LPA to the effluent in the swollen kidney. A potential mechanism is increased release of LPA from activated renal cells in the ureter-ligated kidney.
Both pathways for supply of extracellular LPA may participate in the induction and progression of renal tubulofibrosis.
[Show abstract][Hide abstract] ABSTRACT: Little is known about renal damage to the contralateral kidney after unilateral ureteral obstruction (UUO). Using liquid chromatography-time
of flight-mass spectrometry combined with principal component analysis (PCA), we compared urinary phospholipid profiles before
and two weeks after UUO in rats. PCA revealed that negative ions corresponding to three molecular species of phosphatidylethanolamine
(PE) and two species of phosphatidylglycerol (PG) had a higher score than other phospholipids such as phosphatidylcholine,
phosphatidylinositol, and sphingomyelin. The assigned species of PE and PG were postulated to possess a monoenoic or dienoic
fatty acyl group, and the ratios of their levels in urine from UUO to that in the controls were much higher than those having
a highly polyunsaturated fatty acyl group. These results indicate that PE and PG having a monoenoic or dienoic fatty acyl
group are potential biomarkers for injury of contralateral kidney after UUO.
[Show abstract][Hide abstract] ABSTRACT: Lysophosphatidylcholine (LPC) has diverse biological activities through different mechanisms including its conversion into other types of lipid mediators such as lysophosphatidic acid and 2-arachidonoylglycerol. Previously, we found that a large portion of the fluorescent analog of alkyl type LPC (Bodipy-lysoPAF) on porcine kidney epithelial cells (LLC-PK1) was degraded to monoalkylglycerol by lysophospholipase C-like activity and then quickly internalized into the cells. In this study, we investigated whether exogenous fluorescently labeled LPC (NBD-LPC) itself was also metabolized and internalized by a similar mechanism. LLC-PK1 cells converted NBD-LPC to either NBD-MG, possibly due to lysophospholipase C-like activity of ecto-nucleotide pyrophosphatase/phosphodiesterase-6, or to free fatty acid (FA), due to lysophospholipase activity in the culture medium at both sites. The resultant NBD-MG was further degraded to NBD-FA by lipase activity before or after its uptake into the cells, and a portion of NBD-FA was finally released into the culture medium on the opposite side.
No preview · Article · Sep 2008 · Prostaglandins & other lipid mediators
[Show abstract][Hide abstract] ABSTRACT: To investigate the mechanisms of the release of lyso platelet-activating factor (PAF), an alkyl ether-linked lysophosphatidylcholine, from the kidney epithelial cell line LLC-PK1, the cell monolayer was incubated with a fluorescence-labeled lysoPAF analog, Bodipy-lysoPAF, on either the basolateral or apical side. The fluorescent lipids in the culture media mixed with or without bovine serum albumin at a final concentration of 2% were analyzed by thin layer chromatography. In both cases, two major bands, assignable to Bodipy-lysoPAF and Bodipy-monoglyceride (MG), were detected in the culture medium to which Bodipy-lysoPAF had been added, whereas the culture medium at the opposite side exhibited only the major band of Bodipy-MG. Our results suggest that lysoPAF was degraded by high ecto-lysophospholipase C activity. The possible physiological significance of this metabolic pathway is discussed.
No preview · Article · Mar 2007 · Prostaglandins & other lipid mediators
[Show abstract][Hide abstract] ABSTRACT: In our attempt to investigate the mechanism of the release of platelet-activating factor (PAF) from cells, the erythroleukemic cell line K562 was preloaded with a radiolabeled PAF analogue having an ethylcarbamyl residue, 1-O-octadecyl-2-O-ethylcarbamyl-sn-glycero-3-phosphocholine (ethylcarbamyl-PAF), that is resistant to the hydrolytic action of PAF acetylhydrolase. Its extracellular release was monitored using an albumin back-extraction method, and its metabolic degradation was analyzed by TLC. Phorbol myristate acetate (PMA) was found to stimulate the release of two radioactive lipids, ethylcarbamyl-PAF itself and its metabolite, 1-O-octadecyl-2-ethylcarbamyl-sn-glycerol, whereas only ethylcarbamyl-PAF was released from the resting cells. The increased release of radioactive lipids in PMA-stimulated cells was suggested to be due to stimulated degradation of intracellular ethylcarbamyl-PAF into the cell-permeable metabolite. Thus K562 cells have much less capacity to release intact PAF-like lipid in comparison with its high ability to uptake exogenously added PAF analogues previously described by us and others.
No preview · Article · Feb 2004 · Biological & Pharmaceutical Bulletin
[Show abstract][Hide abstract] ABSTRACT: This study was designed to examine the psychological benefits of anaerobic exercise for older adults. Specifically, strength training was employed to examine the effects on mood and anxiety in a group of healthy but sedentary older women. 36 women (mean age = 68.5 yr.) were randomly assigned to groups given high intensity or moderate intensity strength training or to a control group. Strength training was conducted three days a week for 12 weeks. After the training period, both high and moderate strength-training programs produced marked improvements in muscle strength and body composition compared to the control subjects. The average improvements in the high and moderate intensity strength-training groups for muscle strength were 40.5 and 35.5%, respectively, and for percent body fat 1.52 and 2.50%, respectively. As for psychological changes, both training groups significantly improved positive mood (vigor), and the moderate intensity group significantly reduced trait anxiety compared to means of the control group. Also, both training groups showed some decrease in tension and state anxiety after the training period. These findings provide evidence for the effectiveness of anaerobic training to enhance perception of psychological well-being in older women. A moderate intensity rather than high intensity of training regimen may be more beneficial for sedentary older women to improve psychological health.
No preview · Article · Jan 1999 · Perceptual and Motor Skills
[Show abstract][Hide abstract] ABSTRACT: In this study, we confirmed a previous finding that 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine (methyl-PAF) expresses higher antineoplastic activity against the promyelocytic leukemia cell line HL-60, than against the erythroleukemic cell line K562, and intended to clarify the reason for this. Using an albumin back-exchange method, we measured the rates of binding and internalization of [3H]methyl-PAF by HL-60 and K562 cells. We found that methyl-PAF associated very rapidly and to similar extents with the two types of cells at low concentrations of extracellular bovine serum albumin, but that when bound to the cell surface, it was internalized into HL-60 cells faster than into K562 cells. The internalization of methyl-PAF by HL-60 cells was concentration-independent, intracellular ATP-independent and susceptible to thiol group-modifying reagents and cytochalasin B. Thus the inward transbilayer movement of methyl-PAF seems to occur by cytochalasin B-sensitive protein-mediated mechanism based on passive diffusion not requiring energy, in which SH-groups of protein play a critical role. We also found that the internalization of 1-hexadecanoyl-2-(4,4-difluoro-5,7- dimethyl-4-bora-3a, 4a-diaza-s-indacene-3-pentanoyl)-sn-glycero-3-phosphocholine (Bodipy-C5-PC), whose structure resembles that of methyl-PAF, into HL-60 cells was faster than that into K562 cells. Using a combination of an albumin back-exchange method and observation by confocal laser scanning microscopy, we next examined the intracellular distribution of this fluorescent phospholipid probe after its internalization. Intracellular membranes, especially those peripheral to nuclei, were fluorescence-labeled in both HL-60 and K562 cells, but fluorescence of the nuclear membranes was weak, suggesting that this probe seems mainly to accumulate in intracellular granules, and may interact directly with several key enzymes for phospholipid metabolism, leading to cell injury. Because the difference between the internalization rates of methyl-PAF in HL-60 and K562 cells was correlated with their different susceptibilities to the cytotoxic effect of methyl-PAF, we suggest that the capacities for uptake of methyl-PAF and its accumulation in intracellular membranes are critical factor for its induction of apoptosis. (c) 1998 Elsevier Science B.V.
No preview · Article · Mar 1998 · Biochimica et Biophysica Acta
[Show abstract][Hide abstract] ABSTRACT: Previous studies concerning psychological benefits of exercise among the elderly has focused predominantly on the effects of aerobic exercise. In the present study, psychological and behavioral adaptations in response to 12-weeks of strength training were examined in medically healthy but sedentary 42 older adults (mean age = 68 years). The purpose of this study was to evaluate the effects of high and low intensity resistance training intensity on a) muscular fitness, b) psychological affect, and c) neurocognitive functioning. Subjects were randomly assigned to high intensity/low volume (EXH: 2 sets of 8 to 10 repetitions for 75 to 85% of 1 RM), low intensity/high volume (EXL: 2 sets of 14 to 16 repetitions for 55 to 65% of 1 RM), or no exercise control programs. Prior to and following the 12-week program, subjects underwent comprehensive physiological and psychological evaluations. Physiological assessment included measurements of blood pressure, heart rate, arm and leg muscle strength, body composition, and oxygen consumption (VO2max). Psychological measures included evaluations of mood, anxiety, and physical self-efficacy as well as cognitive functioning. The results of this study indicated that both high and low intensity strength programs were associated with marked improvements in physiological fitness and psychological functioning. Specifically, subjects in the strength training programs increased overall muscle strength by 38.6% and reduced percent body fat by 3.0%. Favorable psychological changes in the strength-trained subjects included improvements in positive and negative mood, trait anxiety, and perceived confidence for physical capability. The treatment effects of neurocognitive functioning were not significant. In summary, this study demonstrated that participation in 12-weeks of high or low intensity strength training can improve overall physical fitness, mood, and physical self-efficacy in older adults while cognitive functioning remains constant.
No preview · Article · Dec 1997 · APPLIED HUMAN SCIENCE Journal of Physiological Anthropology
[Show abstract][Hide abstract] ABSTRACT: We found that extracellular addition of 2% bovine serum albumin (BSA) to a suspension of rabbit platelets after stimulation with platelet-activating factor resulted in a biphasic extraction of [3H]1-O-alkyl-2-O-methyl (or 2-O-methylcarbamyl)-sn-glycero-3-phosphocholine. A fast phase of extraction of the phospholipid probe by BSA was found to be mainly due to removal of the probe remaining in an outer layer of platelet plasma membrane, whereas a second phase of extraction of the probe by BSA was mostly attributed to redistribution of the probe which had been flipped across the plasma membrane. On the basis of analysis of the biphasic extraction by BSA of 1-O-alkyl-2-O-methyl (or methylcarbamyl)-sn-glycero-3-phosphocholine at various times after its addition, we suggested that the radioactive phospholipid accumulated in plasma membrane more than in intracellular membranes of rabbit platelets. In similar experiments with guinea-pig polymorphonuclear leukocytes, we observed a monophasic extraction of 1-O-alkyl-2-O-methyl (or methylcarbamyl)-sn-glycero-3-phosphocholine by BSA, indicating its unidirectional movement across the plasma membrane.
No preview · Article · Apr 1997 · Chemistry and Physics of Lipids
[Show abstract][Hide abstract] ABSTRACT: 1-O-Octadecyl-2-acetyl-sn-glycerol 3-phosphate (octadecylacetyl-GP) and its deacetylation product were used as a model of phosphatidic acid and its lyso derivatives, respectively. The binding, transbilayer movement, and intermembranous transport, which should be related to its metabolism in guinea pig peritoneal polymorphonuclear leukocytes, were studied. The albumin extraction procedure (Tokumura, A., Tsutsumi, T., Yoshida, J., and Tsukatani, H. (1990) Biochim. Biophys. Acta 1044, 91-100) was used for studying the transbilayer movement of [3H]octadecylacetyl-GP. The binding, translocation, and metabolism of octadecylacetylglycerol, a dephosphorylated product of octadecylacetyl-GP, in polymorphonuclear leukocytes were also investigated for comparison. The translocation of octadecylacetyl-GP was dependent on temperature, but not on its concentration (in the range of 1-100 nM). The rate of translocation of octadecylacetyl-GP was much slower than that of octadecylacetylglycerol. Treatment of polymorphonuclear leukocytes with N-ethylmaleimide did not affect the translocation of octadecylacetyl-GP. These results suggest that the transbilayer movement of octadecylacetyl-GP is driven by a diffusion process, not by a carrier protein. From these findings, the process of translocation of octadecylacetyl-GP is concluded to be a rate-limiting step in its metabolic conversion to triglyceride, phosphatidylethanolamine, and phosphatidylcholine.
Preview · Article · May 1992 · Journal of Biological Chemistry
[Show abstract][Hide abstract] ABSTRACT: Platelets and leukocytes are known to degrade platelet-activating factor (PAF), a potential mediator of inflammation, to its lyso-derivative (lyso-PAF) and then convert this to 1-O-alkyl-2-acyl-sn-glycero-3-phosphocholines. However, little is known about the mechanism of internalization of PAF and lyso-PAF, which is a prerequisite for their metabolism within the cells. In this work, the internalization of PAF and lyso-PAF by rabbit platelet and guinea-pig leukocyte plasma-membranes were examined by the washing method with bovine serum albumin. The rates of translocation of PAF and lyso-PAF across guinea-pig plasma membranes were significantly higher than those across rabbit platelets. In these cells, the translocation of PAF was found to be accelerated indirectly by activation of PAF receptors by a small portion of added PAF. Results suggest that a temperature-dependent diffusion process is involved in the internalization of these phospholipids. In both rabbit platelets and guinea-pig leukocytes, the translocation of PAF and lyso-PAF through the plasma membranes was shown to be rate-limiting for the metabolic conversion of these compounds to 1-O-alkyl-2-acyl-sn-glycero-3-phosphocholine.
No preview · Article · Jun 1990 · Biochimica et Biophysica Acta