BACKGROUND: Vagal nerve plays an important role in the stomach function. The cholinergic nerves are the most abundantly distributed nerves in the gastric tissue. It has recently been reported that the vagal nerve is significantly related to both gastric cancer development and progression. However, its relation to the mesenchymal tumor, including MALT lymphoma, is not known. In this study, we investigated the effect of unilateral truncal vagotomy on gastric MALT lymphoma development by using Helicobacter heilmannii-infected mouse model as well as that of bilateral truncal vagotomy on stress-induced ulcer formation. METHODS: In the first part of this study, the distribution of the cholinergic nerves in the rat gastric mucosa and the effect of bilateral truncal vagotomy, as well as various kinds of agents acting on autonomic nerves in rats, were investigated by the histochemical and macroscopic method. In the second part, we employed MALT lymphoma formation in C57BL/6NCrl mice that were infected with Helicobacter heilmannii. A total of 38 infected mice underwent unilateral vagotomy under microscopy. The mice were randomized into 4 groups from which samples were collected; 2, 3, 4 and 6 months after infection. Both the anterior and posterior sides of the stomachs were sampled from each mouse for pathological and immunohistochemical analyses. RESULTS: The bilateral truncal vagotomy significantly suppressed the restraint-induced gastric ulcer formation in rats, while bethanechol, and 6-hydroxydopamine led to an increase of the gastric ulcer formation. In the unilateral truncal vagotomy study using MALT lymphoma, the thickness of the gastric mucosa was reduced in the vagotomized side compared to the non-vagotomized side. Furthermore, the gastric MALT lymphoma was more prominently found in the vagotomized anterior side of stomach compared with that in the non-vagotomized posterior side of stomach. Substance P-immunoreactive nerves markedly increased surrounding the MALT lymphoma and the neurokinin-1 receptor immunoreactive lymphocytes increased within the MALT lymphoma in the vagotomized side. In conclusion, vagotomy enhanced gastric MALT lymphoma development possibly through the substance P-neurokinin-1 receptor pathway.
The alpha/beta-hydrolases are a family of acid-base-nucleophile catalytic triad enzymes with a common fold, but using a wide variety of substrates, having different pH optima, catalyzing unique catalytic reactions and often showing improved chemical and thermo stability. The ABH enzymes are prime targets for protein engineering. Here, we have classified active sites from 51 representative members of 40 structural ABH fold families into eight distinct conserved geometries. We demonstrate the occurrence of a common structural motif, the catalytic acid zone, at the catalytic triad acid turn. We show that binding of an external ligand does not change the structure of the catalytic acid zone and both the ligand-free and ligand-bound forms of the protein belong to the same catalytic acid zone subgroup. We also show that the catalytic acid zone coordinates the position of the catalytic histidine loop directly above its plane, and consequently, fixes the catalytic histidine in a proper position near the catalytic acid. Finally, we demonstrate that the catalytic acid zone plays a key role in multi-subunit complex formation in ABH enzymes, and is involved in interactions with other proteins. As a result, we speculate that each of the catalytic triad residues has its own supporting structural scaffold, similar to the catalytic acid zone, described above, which together form the extended catalytic triad motif. Each scaffold coordinates the function of its respective catalytic residue, and can even compensate for the loss of protein function, if the catalytic amino acid is mutated.
Backgound: The role of enteric nerves has previously been demonstrated in the formation of several gastric diseases. In the present review, the significance of the cholinergic nerves in stress-induced ulcer formation as well as the importance of substance P in the formation of gastric MALT lymphoma is discussed. METHODS: The stress-induced ulcer was induced by the plaster bandage methods in rats. The gastric MALT lymphoma was formed by the peroral infection of gastric mucosal homogenate of the infected mouse in C57BL/6 mice. For the stress-induced ulcer, the distribution of the cholinergic nerves and muscarinic acetylcholine receptors was investigated by acetylcholinesterase histochemistry and autoradiography of water soluble compounds using 3H-quinuclidinyl benzilate was performed. To the MALT lymphoma study, the distribution of the substance P and effect of substance P antagonist, spantide II, was investigated by immunohistochemical studies. RESULTS: The stress induced ulcer formation was shown to be related to the hyperactivity of the cholinergic nerves. The gastric MALT lymphoma was shown to be related to the increased localization of substance P. CONCLUSION: Stress-induced ulceration as a model of hyperactivity of the cholinergic nerves was proved to be a useful approach, while substance P and its role in MALT lymphoma formation may serve as a tool to clarify the neuroimmune modulation of chronic infectious diseases.
Cardiac intracellular lipid accumulation (steatosis) is a pathophysiological phenomenon observed in starvation and diabetes mellitus. Perilipin 2 (PLIN2) is a lipid droplet (LD)-associated protein expressed in non-adipose tissues, including the heart. To explore the pathophysiological function of myocardial PLIN2, we generated transgenic (Tg) mice by cardiac-specific overexpression of PLIN2. Tg hearts showed accumulation of numerous small LDs associated with mitochondrial chains, and high cardiac triacylglycerol (TAG) content (8-fold greater than wild-type (Wt) mice). Despite massive steatosis, cardiac uptake of glucose, fatty acids and VLDL, systolic function, and expression of metabolic genes were comparable in the two genotypes, and no morphological changes were observed by electron microscopy in the Tg hearts. Twenty-four hours fasting markedly reduced steatosis in Tg hearts, while Wt mice showed accumulation of LDs. Although activity of adipose triglyceride lipase in heart homogenate was comparable between Wt and Tg mice, activity of hormone-sensitive lipase (HSL) was 40-50% less in Tg than Wt mice, under both feeding and fasting conditions, suggesting interference of PLIN2 with HSL. Mice generated through crossing of PLIN2-Tg mice and HSL-Tg mice showed cardiac-specific HSL overexpression and complete lack of steatosis. The results suggest that cardiac PLIN2 plays an important pathophysiological role in the development of dynamic steatosis, and that the latter was prevented by upregulation of intracellular lipases, including HSL.
BACKGROUND: The androgen receptor (AR) plays a key role in the development of prostate cancer. AR signalling mediates the expression of androgen-responsive genes, which are involved in prostate cancer development and progression. Our previous chromatin immunoprecipitation study showed that the region of abhydrolase domain containing 2 (ABHD2) includes a functional androgen receptor binding site. In this study, we demonstrated that ABHD2 is a novel androgen-responsive gene that is overexpressed in human prostate cancer tissues. METHODS: The expression levels of ABHD2 in androgen-sensitive cells were evaluated by quantitative reverse transcription polymerase chain reaction and western-blot analyses. LNCaP and VCaP cells with ABHD2 overexpression or short interfering RNA (siRNA) knockdown were used for functional analyses. ABHD2 expression was examined in clinical samples of prostate cancer by immunohistochemistry. RESULTS: We showed that ABHD2 expression is increased by androgen in LNCaP and VCaP cells. This androgen-induced ABHD2 expression was diminished by bicalutamide. While stable expression of ABHD2 affected the enhancement of LNCaP cell proliferation and migration, siRNA-mediated ABHD2 knockdown suppressed cell proliferation and migration. In addition, the siRNA treatment significantly repressed the tumour growth derived from LNCaP cells in athymic mice. Immunohistochemical analysis of ABHD2 expression in tumour specimens showed a positive correlation of ABHD2 immunoreactivity with high Gleason score and pathological N stage. Moreover, patients with high immunoreactivity of ABHD2 showed low cancer-specific survival rates and a resistance to docetaxel-based chemotherapy. CONCLUSION: ABHD2 is a novel androgen-regulated gene that can promote prostate cancer growth and resistance to chemotherapy, and is a novel target for diagnosis and treatment of prostate cancer.
To explore the origins and consequences of tetraploidy in the African clawed frog, we sequenced the Xenopus laevis genome and compared it to the related diploid X. tropicalis genome. We characterize the allotetraploid origin of X. laevis by partitioning its genome into two homoeologous subgenomes, marked by distinct families of 'fossil' transposable elements. On the basis of the activity of these elements and the age of hundreds of unitary pseudogenes, we estimate that the two diploid progenitor species diverged around 34 million years ago (Ma) and combined to form an allotetraploid around 17-18 Ma. More than 56% of all genes were retained in two homoeologous copies. Protein function, gene expression, and the amount of conserved flanking sequence all correlate with retention rates. The subgenomes have evolved asymmetrically, with one chromosome set more often preserving the ancestral state and the other experiencing more gene loss, deletion, rearrangement, and reduced gene expression.
To investigate the mechanism for low pH adaptation by a carboxylesterase, structural and biochemical analyses of EstFa_R (a recombinant, slightly acidophilic carboxylesterase from Ferroplasma acidiphilum) and SshEstI (an alkaliphilic carboxylesterase from Sulfolobus shibatae DSM5389) were performed. Although a previous proteomics study by another group showed that the enzyme purified from F. acidiphilum contained an iron atom, EstFa_R did not bind to iron as analyzed by inductively coupled plasma MS and isothermal titration calorimetry. The crystal structures of EstFa_R and SshEstI were determined at 1.6- and 1.5-A resolutions, respectively. EstFa_R had a catalytic triad with an extended hydrogen bond network that was not observed in SshEstI. Quadruple mutants of both proteins were created to remove or introduce the extended hydrogen bond network. The mutation on EstFa_R enhanced its catalytic efficiency and gave it an alkaline pH optimum, whereas the mutation on SshEstI resulted in opposite effects (i.e. a decrease in the catalytic efficiency and a downward shift in the optimum pH). Our experimental results suggest that the low pH optimum of EstFa_R activity was a result of the unique extended hydrogen bond network in the catalytic triad and the highly negatively charged surface around the active site. The change in the pH optimum of EstFa_R happened simultaneously with a change in the catalytic efficiency, suggesting that the local flexibility of the active site in EstFa_R could be modified by quadruple mutation. These observations may provide a novel strategy to elucidate the low pH adaptation of serine hydrolases.
Title: Structural revision of kynapcin-12 by total synthesis, and inhibitory activities against prolyl oligopeptidase and cancer cells Takahashi S, Yoshida A, Uesugi S, Hongo Y, Kimura K, Matsuoka K, Koshino H Ref: Bioorganic & Medicinal Chemistry Lett, 24:3373, 2014 : PubMed
Kynapcin-12 is a prolyl oligopeptidase (POP) inhibitor isolated from Polyozellus multiplex, and its structure was assigned as 1 having a p-hydroquinone moiety by spectroscopic analyses and chemical means. This Letter describes the total syntheses of the proposed structure 1 for kynapcin-12 and 2',3'-diacetoxy-1,5',6',4''-tetrahydroxy-p-terphenyl 2 isolated from Boletopsis grisea, revising the structure of kynapcin-12 to the latter. These syntheses involved double Suzuki-Miyaura coupling, CAN oxidation, and LTA oxidation as key steps. The inhibitory activities of synthetic compounds against POP and cancer cells were also evaluated.
Methionine- and choline-deficient diet (MCD) is a model for nonalcoholic steatohepatitis (NASH) in rodents. However, the mechanism of NASH development by dietary methionine/choline deficiency remains undetermined. To elucidate the early metabolic changes associated with MCD-NASH, serum metabolomic analysis was performed using mice treated with MCD and control diet for 3 days and 1 week, revealing significant increases in oleic and linoleic acids after MCD treatment. These increases were correlated with reduced body weight and white adipose tissue (WAT) mass, increased phosphorylation of hormone-sensitive lipase, and up-regulation of genes encoding carboxylesterase 3 and beta2-adrenergic receptor in WAT, indicating accelerated lipolysis in adipocytes. The changes in serum fatty acids and WAT by MCD treatment were reversed by methionine supplementation, and similar alterations were detected in mice fed a methionine-deficient diet (MD), thus demonstrating that dietary methionine deficiency enhances lipolysis in WAT. MD treatment decreased glucose and increased fibroblast growth factor 21 in serum, thus exhibiting a similar metabolic phenotype as the fasting response. Comparison between MCD and choline-deficient diet (CD) treatments suggested that the addition of MD-induced metabolic alterations, such as WAT lipolysis, to CD-induced hepatic steatosis promotes liver injury. Collectively, these results demonstrate an important role for dietary methionine deficiency and WAT lipolysis in the development of MCD-NASH.
Although fasting induces hepatic triglyceride (TG) accumulation in both rodents and humans, little is known about the underlying mechanism. Because parasympathetic nervous system activity tends to attenuate the secretion of very-low-density-lipoprotein-triglyceride (VLDL-TG) and increase TG stores in the liver, and serum cholinesterase activity is elevated in fatty liver disease, the inhibition of the parasympathetic neurotransmitter acetylcholinesterase (AChE) may have some influence on hepatic lipid metabolism. To assess the influence of AChE inhibition on lipid metabolism, the effect of physostigmine, an AChE inhibitor, on fasting-induced increase in liver TG was investigated in mice. In comparison with ad libitum-fed mice, 30 h fasting increased liver TG accumulation accompanied by a downregulation of sterol regulatory element-binding protein 1 (SREBP-1) and liver-fatty acid binding-protein (L-FABP). Physostigmine promoted the 30 h fasting-induced increase in liver TG levels in a dose-dependent manner, accompanied by a significant fall in plasma insulin levels, without a fall in plasma TG. Furthermore, physostigmine significantly attenuated the fasting-induced decrease of both mRNA and protein levels of SREBP-1 and L-FABP, and increased IRS-2 protein levels in the liver. The muscarinic receptor antagonist atropine blocked these effects of physostigmine on liver TG, serum insulin, and hepatic protein levels of SREBP-1 and L-FABP. These results demonstrate that AChE inhibition facilitated fasting-induced TG accumulation with up regulation of the hepatic L-FABP and SREBP-1 in mice, at least in part via the activation of muscarinic acetylcholine receptors. Our studies highlight the crucial role of parasympathetic regulation in fasting-induced TG accumulation, and may be an important source of information on the mechanism of hepatic disorders of lipid metabolism.
Lecithin-cholesterol acyltransferase (LCAT) is an enzyme involved in maintaining cholesterol homeostasis. In familial LCAT deficiency (FLD), abnormal lipid deposition causes renal injury and nephrotic syndrome, frequently progressing to ESRD. Here, we describe a 63-year-old Japanese woman with no family history of renal disease who presented with nephrotic syndrome. The laboratory data revealed an extremely low level of serum HDL and undetectable serum LCAT activity. Renal biopsy showed glomerular lipid deposition with prominent accumulation of foam cells, similar to the histologic findings of FLD. In addition, she had subepithelial electron-dense deposits compatible with membranous nephropathy, which are not typical of FLD. A mixing test and coimmunoprecipitation study demonstrated the presence of an inhibitory anti-LCAT antibody in the patient's serum. Immunohistochemistry and immunofluorescence detected LCAT along parts of the glomerular capillary walls, suggesting that LCAT was an antigen responsible for the membranous nephropathy. Treatment with steroids resulted in complete remission of the nephrotic syndrome, normalization of serum LCAT activity and HDL level, and disappearance of foam cell accumulation in renal tissue. In summary, inhibitory anti-LCAT antibody can lead to glomerular lesions similar to those observed in FLD.
Title: In vitro evaluation of inhibitory effects of antidiabetic and antihyperlipidemic drugs on human carboxylesterase activities Fukami T, Takahashi S, Nakagawa N, Maruichi T, Nakajima M, Yokoi T Ref: Drug Metabolism & Disposition: The Biological Fate of Chemicals, 38:2173, 2010 : PubMed
Human carboxylesterase (CES) 1A is responsible for the biotransformation of angiotensin-converting enzyme (ACE) inhibitors such as imidapril and temocapril. Because antidiabetic or antihyperlipidemic drugs are often coadministered with ACE inhibitors in clinical pharmacotherapy, the inhibitory effect of these drugs on CES1A1 enzyme activity was investigated. In addition, the inhibitory effect on CES2 enzyme activity was evaluated to compare it with that on CES1A1. The inhibitory effects were evaluated with 11 antidiabetic and 12 antihyperlipidemic drugs. The imidapril hydrolase activity by recombinant CES1A1 was substantially inhibited by lactone ring-containing statins such as simvastatin and lovastatin and thiazolidinediones such as troglitazone and rosiglitazone. The activity in human liver microsomes was also strongly inhibited by simvastatin and troglitazone (K(i) = 0.8 +/- 0.1 and 5.6 +/- 0.2 muM, respectively). However, statins containing no lactone ring such as pravastatin and fluvastatin did not show strong inhibition. 7-Ethyl-10-[4-(1-piperidono)-1-piperidono]carbonyloxycamptothecin hydrolase activity by recombinant human CES2 was substantially inhibited by fenofibrate (K(i) = 0.04 +/- 0.01 muM) as well as by simvastatin (0.67 +/- 0.09 muM). Other fibrates such as clinofibrate and bezafibrate did not show strong inhibition. Thus, the inhibitory effects of the thiazolidinediones and fenofibrate on CES1A1 and CES2 were different. Some statins such as simvastatin and lovastatin, thiazolidinediones, and fenofibrate might attenuate the drug efficacy of prodrugs biotransformed by CES1A and CES2.
Title: Arylacetamide deacetylase is a determinant enzyme for the difference in hydrolase activities of phenacetin and acetaminophen Watanabe A, Fukami T, Takahashi S, Kobayashi Y, Nakagawa N, Nakajima M, Yokoi T Ref: Drug Metabolism & Disposition: The Biological Fate of Chemicals, 38:1532, 2010 : PubMed
Phenacetin was withdrawn from the market because it caused renal failure in some patients. Many reports indicated that the nephrotoxicity of phenacetin is associated with the hydrolyzed metabolite, p-phenetidine. Acetaminophen (APAP), the major metabolite of phenacetin, is also hydrolyzed to p-aminophenol, which is a nephrotoxicant. However, APAP is safely prescribed if used in normal therapeutic doses. This background prompted us to investigate the difference between phenacetin and APAP hydrolase activities in human liver. In this study, we found that phenacetin is efficiently hydrolyzed in human liver microsomes (HLM) [CL(int) 1.08 +/- 0.02 microl/(min . mg)], whereas APAP is hardly hydrolyzed [0.02 +/- 0.00 microl/(min . mg)]. To identify the esterase involved in their hydrolysis, the activities were measured using recombinant human carboxylesterase (CES) 1A1, CES2, and arylacetamide deacetylase (AADAC). Among these, AADAC showed a K(m) value (1.82 +/- 0.02 mM) similar to that of HLM (3.30 +/- 0.16 mM) and the highest activity [V(max) 6.03 +/- 0.14 nmol/(min . mg)]. In contrast, APAP was poorly hydrolyzed by the three esterases. The large contribution of AADAC to phenacetin hydrolysis was demonstrated by the prediction with a relative activity factor. In addition, the phenacetin hydrolase activity by AADAC was activated by flutamide (5-fold) as well as that in HLM (4-fold), and the activity in HLM was potently inhibited by eserine, a strong inhibitor of AADAC. In conclusion, we found that AADAC is the principal enzyme responsible for the phenacetin hydrolysis, and the difference of hydrolase activity between phenacetin and APAP is largely due to the substrate specificity of AADAC.
BACKGROUND/OBJECTIVES: Subcutaneous adipose tissue grows rapidly during the first months of life. Lipoprotein lipase (LPL) has a quantitatively important function in adipose tissue fat accumulation and insulin-like growth factor-I (IGF-I) is a determinant of neonatal growth. Recent studies showed that LPL mass in non-heparinized serum (LPLm) was an index of LPL-mediated lipolysis of plasma triacylglycerol (TG). The objective was to know the influence of serum LPL and IGF-I on neonatal subcutaneous fat growth, especially on catch-up growth in low birth weight infants. SUBJECTS/METHODS: We included 47 healthy neonates (30 males, 17 females), including 7 small for gestational age. We measured serum LPLm and IGF-I concentrations at birth and 1 month, and analyzed those associations with subcutaneous fat accumulation. RESULTS: Serum LPLm and IGF-I concentrations increased markedly during the first month, and positively correlated with the sum of skinfold thicknesses both at birth (r=0.573, P=0.0001; r=0.457, P=0.0035) and at 1 month (r=0.614, P<0.0001; r=0.787, P<0.0001, respectively). In addition, serum LPLm concentrations correlated inversely to very low-density lipoprotein (VLDL)-TG levels (r=-0.692, P<0.0001 at birth; r=-0.429, P=0.0052 at 1 month). Moreover, the birth weight Z-score had an inverse association with the postnatal changes in individual serum LPLm concentrations (r=-0.639, P<0.0001). CONCLUSIONS: Both serum LPLm and IGF-I concentrations were the determinants of subcutaneous fat accumulation during the fetal and neonatal periods. During this time, LPL-mediated lipolysis of VLDL-TG may be one of the major mechanisms of rapid growth in subcutaneous fat tissue. Moreover, LPL, as well as IGF-I, may contribute to catch-up growth in smaller neonates.
The gene encoding acetylcholinesterase (AChE) was cloned from common carp muscle tissue. The full-length cDNA was 2368 bp that contains a coding region of 1902 bp, corresponding to a protein of 634 amino acids. The deduced amino acid sequence showed a significant homology with those of ichthyic AChEs and several common features among them, including T peptide encoded by exon T in the C-terminus. Three yeast expression vectors were constructed and introduced into the yeast Pichia pastoris. The transformant harboring carp AChE gene lacking exon T most effectively produced AChE activity extracellularly. The replacement of the native signal sequence with the yeast alpha-factor prepro signal sequence rather decreased the production. A decrease in cultivation temperature from 30 to 15 degrees C increased the activity production 32.8-fold. The purified recombinant AChE lacking T peptide, eluted as a single peak with a molecular mass of about 230 kDa on the gel filtration chromatography, exhibited the specific activity of 4970 U/mg. On the SDS-PAGE, three proteins with molecular masses of 73, 54, and 22 kDa were observed. These proteins were N-glycosylated, and their N-terminal sequence showed that the latter two were produced from the former probably by proteolytic cleavage at the C-terminal region. Thus, the recombinant AChE is homotrimer of three identical subunits with 73 kDa. The optimal temperature and pH of the recombinant were comparable to those of the native enzyme purified previously, but the values of kinetic parameters and the sensitivities to substrate inhibition and inhibitors were considerably different between them.
Increased fatty acid (FA) flux and intracellular lipid accumulation (steatosis) give rise to cardiac lipotoxicity in both pathological and physiological conditions. Since hormone-sensitive lipase (HSL) contributes to intracellular lipolysis in adipose tissue and heart, we investigated the impact of HSL disruption on cardiac energy metabolism in response to fasting and refeeding. HSL-knockout (KO) mice and wild-type (WT) littermates were fasted for 24 h, followed by approximately 6 h of refeeding. Plasma FA concentration in WT mice was elevated twofold with fasting, whereas KO mice lacked this elevation, resulting in twofold lower cardiac FA uptake compared with WT mice. Echocardiography showed that fractional shortening was 15% decreased during fasting in WT mice and was associated with steatosis, whereas both of these changes were absent in KO mice. Compared with Langendorff-perfused hearts isolated from fasted WT mice, the isolated KO hearts also displayed higher contractile function and a blunted response to FA. Although cardiac glucose uptake in KO mice was comparable with WT mice under all conditions tested, cardiac VLDL uptake and lipoprotein lipase (LPL) activity were twofold higher in KO mice during fasting. The KO hearts showed undetectable activity of neutral cholesteryl esterase and 40% lower non-LPL triglyceride lipase activity compared with WT hearts in refed conditions accompanied by overt steatosis, normal cardiac function, and increased mRNA expression of adipose differentiation-related protein. Thus, the dissociation between cardiac steatosis and functional sequelae observed in HSL-KO mice suggests that excess FA influx, rather than steatosis per se, appears to play an important role in the pathogenesis of cardiac lipotoxicity.
Title: Different inhibitory effects in rat and human carboxylesterases Takahashi S, Katoh M, Saitoh T, Nakajima M, Yokoi T Ref: Drug Metabolism & Disposition: The Biological Fate of Chemicals, 37:956, 2009 : PubMed
In vitro inhibition studies on drug-metabolizing enzyme activity are useful for understanding drug-drug interactions and for drug development. However, the profile of the inhibitory effects of carboxylesterase (CES) activity has not been fully investigated concerning species and tissue differences. In the present study, we measured the inhibitory effects of 15 drugs and 1 compound on CES activity using liver and jejunum microsomes and cytosol in human and rat. In addition, the inhibition constant (K(i) values) and patterns were determined for the compounds exhibiting strong inhibition. Hydrolysis of imidapril and irinotecan hydrochloride (CPT-11) is catalyzed mainly by CES1 and CES2, respectively. In the inhibition study, imidaprilat formation from imidapril in human liver was strongly inhibited by nordihydroguaiaretic acid (NDGA) and procainamide. The inhibition profile and pattern were similar in human liver and rat liver. The compounds showing potent inhibition were similar between liver and jejunum. The K(i) value of NDGA (K(i) = 13.3 +/- 1.5 microM) in human liver microsomes was 30-fold higher than that in rat liver microsomes (K(i) = 0.4 +/- 0.0 microM). On the other hand, 7-ethyl-10-hydroxycamptothecin (SN-38) formation from CPT-11 was not inhibited except by carvedilol, manidipine, and physostigmine. The K(i) value of physostigmine (K(i) = 0.3 +/- 0.0 microM) in human jejunum cytosol was 10-fold lower than that in rat jejunum cytosol (K(i) = 3.1 +/- 0.4 microM) and was similar to that for manidipine. The present study clarified the species differences in CES inhibition. These results are useful for the development of prodrugs.
OBJECTIVE: Human carboxylesterase (CES) 1A1 gene (14 exons) and CES1A3 pseudogene (six exons) are inverted and duplicated genes in a reference sequence (NT_010498). In contrast, earlier studies reported the CES1A2 gene (14 exons) instead of the CES1A3 pseudogene. The sequences of the CES1A2 gene downstream and upstream of intron 1 are identical with those of the CES1A1 and CES1A3 genes, respectively. A CES1A1 variant of which exon 1 is converted with that of the CES1A3 gene (the transcript is CES1A2) has recently been identified. We sought to clarify the confusing gene structure of human CES1A. METHODS: A panel of 55 human liver as well as 318 blood samples (104 Caucasians, 107 African-Americans, and 107 Japanese) was used to clarify the gene structures of CES1A1, CES1A2, and CES1A3. Real-time reverse transcription-PCR and western blot analysis were carried out. Imidapril hydrolase activity in human liver microsomes and cytosol was determined by liquid chromatography-mass spectrometry (LC-MS)/MS. RESULTS: By PCR analyses, we found that the CES1A2 gene is a variant of the CES1A3 gene. Four haplotypes, A (CES1A1 wild type and CES1A3), B (CES1A1 wild type and CES1A2), C (CES1A1 variant and CES1A3), and D (CES1A1 variant and CES1A2), were demonstrated. Ethnic differences were observed in allele frequencies of CES1A1 variant (17.3% in Caucasians and African-Americans and 25.2% in Japanese) and CES1A2 gene (14.4% in Caucasians, 5.1% in African-Americans, and 31.3% in Japanese). In human livers whose diplotype was A/A and C/C or C/D, no CES1A2 and CES1A1 mRNA was detected, respectively. In the other participants, the CES1A1 mRNA levels were higher than the CES1A2 mRNA levels. The CES1A proteins translated from CES1A1 mRNA and CES1A2 mRNA were detected in both human liver microsomes and cytosol fractions suggesting that the differences in exon 1 encoding a signal peptide did not affect the subcellular localization. Imidapril hydrolase activities reflected the CES1A protein levels. CONCLUSION: We found that the CES1A2 gene is a variant of the CES1A3 pseudogene. The findings presented here significantly increase our understanding about the gene structure and expression properties of human CES1A.
OBJECTIVES: Systemic disorder is a characteristic of advanced pancreatic cancer. Clinical prognostic factors in earlier disease state than terminal stage are expected to be sensitive markers for the foresight of systemic disorder. This study aimed to find the associations between these sensitive markers and morphological factors of primary tumor that may indicate finding a way of pathogenesis of systemic disorder. METHODS: The current study examined 75 patients who received macroscopic curative resection for pancreatic cancer in our institution as follows: (1) identification of clinical prognostic factors at initial recurrence after resection of primary tumor and (2) analysis of correlations between clinical prognostic factors and histological findings in primary tumor. RESULTS: Important prognostic factors were peritoneal dissemination and serum levels of carbohydrate antigen 19-9 and cholinesterase. Only low levels of serum cholinesterase correlated to nerve plexus invasion in histological findings of primary tumor. Patients with low cholinesterase levels show systemic disorder, including poor performance status, anemia, and hypoalbuminemia. CONCLUSIONS: Nerve invasion may thus result in low functional state of the liver followed by systemic disorder. This mechanism may be useful for elucidating cancer cachexia in future studies.
Title: Allosteric kinetics of human carboxylesterase 1: species differences and interindividual variability Takahashi S, Katoh M, Saitoh T, Nakajima M, Yokoi T Ref: J Pharm Sci, 97:5434, 2008 : PubMed
Esterified drugs such as imidapril, derapril, and oxybutynin hydrolyzed by carboxylesterase 1 (CES1) are extensively used in clinical practice. The kinetics using the CES1 substrates have not fully clarified, especially concerning species and tissue differences. In the present study, we performed the kinetic analyses in humans and rats in order to clarify these differences. The imidaprilat formation from imidapril exhibited sigmoidal kinetics in human liver microsomes (HLM) and cytosol (HLC) but Michaelis-Menten kinetics in rat liver microsomes and cytosol. The 2-cyclohexyl-2-phenylglycolic acid (CPGA) formation from oxybutynin were not detected in enzyme sources from rats, although HLM showed high activity. The kinetics were clarified to be different among species, tissues, and preparations. In individual HLM and HLC, there was large interindividual variability in imidaprilat (31- and 24-fold) and CPGA formations (15- and 9-fold). Imidaprilat formations exhibited Michaelis-Menten kinetics in HLM and HLC with high activity but sigmoidal kinetics in those with low activity. CPGA formations showed sigmoidal kinetics in high activity HLM but Michaelis-Menten kinetics in HLM with low activity. We revealed that the kinetics were different between individuals. These results could be useful for understanding interindividual variability and for the development of oral prodrugs.
Intracellular lipid accumulation (steatosis) and resultant lipotoxicity are key features of diabetic cardiomyopathy. Since cardiac hormone-sensitive lipase (HSL) is activated in diabetic mice, we sought to explore a pathophysiological function of cardiac HSL in the development of diabetic cardiomyopathy. Transgenic (Tg) mice with heart-specific HSL overexpression were generated, and cardiac histology, function, lipid profile, and gene expressions were analyzed after induction of diabetes by streptozotocin. Electron microscopy showed numerous lipid droplets in wild-type (Wt) hearts after 3 wk of diabetes, whereas Tg mice showed no lipid droplet accumulation. Cardiac content of acylglycerides was increased approximately 50% with diabetes in Wt mice, whereas this was blunted in Tg hearts. Cardiac lipid peroxide content was twofold lower in Tg hearts than in Wt hearts. The mRNA expressions for peroxisome proliferator-activated receptor-alpha, genes for triacylglycerol synthesis, and lipoprotein lipase were increased with diabetes in Wt hearts, whereas this induction was absent in Tg hearts. Expression of genes associated with lipoapoptosis was decreased, whereas antioxidant protein metallothioneins were increased in diabetic Tg hearts. Diabetic Wt hearts showed interstitial fibrosis and increased collagen content. However, Tg hearts displayed no overt fibrosis, concomitant with decreased expression of collagens, transforming growth factor-beta, and matrix metalloproteinase 2. Notably, mortality during the experimental period was approximately twofold lower in diabetic Tg mice compared with Wt mice. In conclusion, since HSL overexpression inhibits cardiac steatosis and fibrosis by apparently hydrolyzing toxic lipid metabolites, cardiac HSL could be a therapeutic target for regulating diabetic cardiomyopathy.
Cytomegalovirus (CMV)-associated pancreatitis is rare after allogeneic hematopoietic stem cell transplantation (SCT). We describe a patient who developed pancreatic hyperamylasemia and hyperlipasemia in association with CMV infection after cord blood transplantation (CBT). A 31-year-old man with acute myelogenous leukemia underwent CBT. A neutrophil count consistently greater than 500/microL was achieved on day +21. Positive results for CMV antigenemia on days +35 and +67 prompted 2 courses of preemptive therapy with ganciclovir or foscarnet. The CMV antigenemia value again became positive on day +134. On day +141, serum amylase and lipase activities markedly increased to 1221 IU/L and 894 IU/L, respectively. The patient had no abdominal symptoms. Ultrasonography and computed tomography results showed no abnormalities of the pancreas. A diagnosis of possible pancreatitis was made. After the initiation of foscarnet therapy, the CMV antigenemia results soon became negative, and serum amylase and lipase activities returned to normal. Therefore, CMV infection was considered to play a major role in the development of pancreatic hyperamylasemia and hyperlipasemia in our patient. The present report indicates that CMV infection should be included in the differential diagnosis for patients with pancreatic hyperamylasemia after SCT.
Title: Role of nuclear factor-kappaB in gastric ulcer healing in rats Takahashi S, Fujita T, Yamamoto A Ref: American Journal of Physiology Gastrointest Liver Physiol, 280:G1296, 2001 : PubMed
We investigated the role of nuclear factor-kappaB (NF-kappaB) in gastric ulcer healing in rats. NF-kappaB was activated in ulcerated tissue but not in normal mucosa, and the level of the activation was decreased with ulcer healing. NF-kappaB activation was observed in fibroblasts, monocytes/macrophages, and neutrophils. Treatment of gastric fibroblasts, isolated from the ulcer base, with interleukin-1beta activated NF-kappaB and the subsequently induced cyclooxygenase-2 and cytokine-induced neutrophil chemoattractant-1 (CINC-1) mRNA expression. Inhibition of activated NF-kappaB action resulted in suppression of both their mRNA expression and increases in PGE(2) and CINC-1 levels induced by interleukin-1beta. Persistent prevention of NF-kappaB activation caused an impairment of ulcer healing in rats. Gene expression of interleukin-1beta, CINC-1, cyclooxygenase-2, and inducible nitric oxide synthase in ulcerated tissue had been inhibited before the delay in ulcer healing became manifest. The increased levels of cyclooxygenase-2 protein and PGE(2) production were also reduced. These results demonstrate that NF-kappaB, activated in ulcerated tissue, might upregulate the expression of healing-promoting factors responsible for gastric ulcer healing in rats.
Title: Independent production of two molecular forms of a recombinant Rhizopus oryzae lipase by KEX2-engineered strains of Saccharomyces cerevisiae Takahashi S, Ueda M, Tanaka A Ref: Applied Microbiology & Biotechnology, 52:534, 1999 : PubMed
A mixture of rProROL having the full-length prosequence (97 amino acids) for a recombinant lipase of Rhizopus oryzae (rROL) and r28ROL having 28 amino acids of the same prosequence has been produced as active forms by Saccharomyces cerevisiae [Takahashi et al. (1998) J Ferment Bioeng 86: 164-168]. However, the separation of rProROL and r28ROL has not been successful due to their identical behavior on column chromatographs, presumably because of the similarity of their surface properties. The independent production of two different molecular forms of rROL was carried out using KEX2-engineered strains of S. cerevisiae, since r28ROL was predicted to be a product from rProROL by a Kex2-like protease. rProROL was successfully obtained by expression of the ROL gene in the S. cerevisiae kex2 strain in which the KEX2 gene encoding Kex2p was disrupted, while r28ROL was obtained by co-expression of the gene (KEX2 delta 613) encoding the soluble form of the C-terminal truncated Kex2 protease (sKex2p). The specific lipase activities of rProROL and r28ROL were 92.9 U/mg and 140 U/mg, respectively. rProROL was stable at pH 2.2-8.0, and showed the optimal reaction temperature to be 30-35 degrees C with a T50 of 55 degrees C (T50 is the temperature resulting in 50% loss of activity). The values for r28ROL were pH 3.0-10.0, 25-30 degrees C, and 40 degrees C, respectively. rProROL was an N-linked glycosylated form, but r28ROL was not. The enhanced thermostability of rProROL did not seem to be due to the N-linked glycosylation, as judged by the results of the Endo H treatment. rProROL had the highest esterase activity toward p-nitrophenyl laurate (C12), whereas r28ROL had the highest esterase activity toward p-nitrophenyl caprylate (C8) and stearate (C18). These results suggest that the distinct properties of these two forms of lipase are caused by the different length of the ROL prosequence.
Title: Increase in neutral cholesteryl ester hydrolase activity produced by extralysosomal hydrolysis of high-density lipoprotein cholesteryl esters in rat hepatoma cells (H-35) Shimada A, Tamai T, Oida K, Takahashi S, Suzuki J, Nakai T, Miyabo S Ref: Biochimica & Biophysica Acta, 1215:126, 1994 : PubMed
The metabolism of high-density lipoprotein-associated cholesteryl esters (HDL-CE) in liver cells is not well understood. We studied the possible role of lysosomal and extralysosomal pathways on such metabolism by measuring the uptake and hydrolysis of HDL-CE in H-35 rat hepatoma cells. Incubation of cells with [3H]cholesteryl ester-labeled HDL led to the intracellular accumulation of both 3H-free cholesterol and [3H]cholesteryl ester. The ratio of 3H-free cholesterol/[3H]cholesteryl ester increased with an increase in incubation time even in the presence of chloroquine. Because chloroquine did not inhibit the conversion of cholesteryl ester to free cholesterol, the hydrolysis of HDL-CE may have been catalyzed by an extralysosomal enzyme, perhaps by neutral cholesteryl ester hydrolase (NCEH). When we incubated cells with increasing concentrations of HDL, NCEH activity increased. This increase in enzyme activity was not inhibited by the addition of chloroquine. A complex of dimyristoylphosphatidylcholine (DMPC)/apo HDL/cholesteryl ester enhanced the activity as well as native HDL. Neither the DMPC/apo HDL nor the DMPC/cholesteryl ester complex affected the activity, suggesting that apo HDL may be required for the uptake of HDL-CE. The present study demonstrated that the extralysosomal hydrolysis by NCEH is operating in the metabolism of HDL-CE in hepatoma cells.
