[Show abstract][Hide abstract] ABSTRACT: Systemic administration of the potent vasodilating peptide adrenomedullin reduces cardiac and renal fibrosis in hypertensive animals. Here, we investigated the effects of kidney-specific adrenomedullin gene delivery in normotensive rats after unilateral ureteral obstruction, an established model of renal tubulointerstitial fibrosis. Overexpression of exogenous adrenomedullin in the renal interstitium following ureteral obstruction significantly prevented fibrosis and proliferation of tubular and interstitial cells. In this model, there is upregulation of connective tissue growth factor (CTGF) mRNA expression and extracellular signal-regulated kinase (ERK) phosphorylation, and adrenomedullin overexpression suppressed both of these activities without altering the blood pressure. In NRK-49F renal fibroblasts, adrenomedullin reduced transforming growth factor-beta-induced CTGF and fibronectin mRNA upregulation through the cyclic AMP/protein kinase A signaling pathway, and suppressed ERK phosphorylation and cell proliferation. In the kidneys with an obstructed ureter, adrenomedullin receptor gene expression was upregulated along with cyclic AMP production in kidney slices. The latter effect was partially blocked by a neutralizing antibody to adrenomedullin, indicating that an endogenous peptide-receptor system was activated. Our results show that overexpression of exogenous adrenomedullin in the ureteral-obstructed kidney prevents tubulointerstitial fibrosis and cell proliferation through the cyclic AMP-mediated decrease of CTGF induction and ERK phosphorylation.
Kidney International 08/2008; 74(1):70-80. · 8.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We quantitatively assessed the expression of cytokine receptors (interleukin-2 receptor (IL-2R), IL-3R, IL-4R, IL-5R, IL-6R, IL-7R, granulocyte-macrophage colony-stimulating factor R (GM-CSFR), G-CSFR, c-fms, c-mpl, c-kit and FLT3) in cells from 211 adults with acute lymphoblastic leukemia (ALL) by flow cytometry and determined their prevalence and clinical significance. Although all cytokine receptors were expressed to various degrees, the levels of IL-3R α-chain (IL-3Rα), IL-2Rα, IL-2Rβ, IL-7Rα, common-Rγ(γc), c-mpl, c-kit and FLT3 exhibited a wide spectrum ⩾2000 sites/cell. Among them, IL-3Rα, IL-2Rα and FLT3 were highly expressed in B-lineage ALL, whereas IL-7Rα, γc and c-kit predominated in T-lineage ALL. Higher levels of IL-3Rα, IL-2Rα, c-kit and FLT3 correlated with the expression of CD13/33. Increased IL-2Rα levels related to the presence of Philadelphia chromosome (Ph), leukocytosis and shorter event-free survival (EFS). C-kit preferred in male. Elevated FLT3 levels correlated with age ⩾60 years. Multivariate analysis in B-lineage ALL revealed only IL-2Rα (P=0.028) and Ph (P=0.020) as independent factors for EFS. These findings suggest that several cytokine receptors associated with certain cellular and clinical features, but IL-2Rα solely had a prognostic value and should be considered as a major prognostic factor for adult ALL that is comparable with Ph.
[Show abstract][Hide abstract] ABSTRACT: Brain natriuretic peptide (BNP) is a potent vasorelaxing and natriuretic peptide that is secreted from the heart and has cardioprotective properties. We have previously generated hypotensive transgenic mice (BNP-Tg mice) that overproduce BNP in the liver, which is released into the circulation. Using this animal model, we successfully demonstrated the amelioration of renal injury after renal ablation and in proliferative glomerulonephritis. Glomerular hyperfiltration is an early haemodynamic derangement, representing one of the key mechanisms of the pathogenesis of diabetic nephropathy. Based on the suggested involvement of increased endogenous natriuretic peptides, the aim of this study was to investigate their role in the development and progression of diabetic nephropathy.
We evaluated the progression of renal injury and fibrogenesis in BNP-Tg mice with diabetes induced by streptozotocin. We also investigated the effect of BNP on high glucose-induced signalling abnormalities in mesangial cells.
After induction of diabetes, control mice exhibited progressively increased urinary albumin excretion with impaired renal function, whereas these changes were significantly ameliorated in BNP-Tg mice. Notably, diabetic BNP-Tg mice revealed minimal mesangial fibrogenesis with virtually no glomerular hypertrophy. Glomerular upregulation of extracellular signal-regulated kinase, TGF-beta and extracellular matrix proteins was also significantly inhibited in diabetic BNP-Tg mice. In cultured mesangial cells, activation of the above cascade under high glucose was abrogated by the addition of BNP.
Chronic excess of BNP prevents glomerular injury in the setting of diabetes, suggesting that renoprotective effects of natriuretic peptides may be therapeutically applicable in preventing the progression of diabetic nephropathy.
[Show abstract][Hide abstract] ABSTRACT: In this study, the mRNA expression of p14(ARF) in t(8;21)AML cells was found to be significantly lower than acute myelocytic leukemia (AML) cells without t(8;21) chromosome abnormality, which was concordant with previous observation by Linggi et al. that AML1-MTG8 represses the transcription of p14(ARF). Although p53 mRNA expression level of t(8;21)AML cells was not low, p53 protein expression was reduced in t(8;21)AML cells. Genotoxic damage by ionizing radiation did not induce p53 upregulation in t(8;21)AML cells. Since p14(ARF) has been demonstrated to inhibit p53 degradation by binding to MDM2, repression of p14(ARF) expression in t(8;21)AML may facilitate the degradation of p53 by MDM2. Low p14(ARF) in t(8;21)AML may also account for the absence of upregulation of p53 by ionizing radiation. Then, we have shown that p53 expression level was inversely correlated with S/G2/M population of cell cycle in AML cells. Most of the t(8;21)AML are considered to be in p53(low) S/G2/M(high). It is now widely known that formation of AML1-MTG8 by t(8;21) translocation is a very early event in leukemogenesis, and AML1-MTG8 alone might have limited proliferative potential. Then, secondary oncogenic events such as activated receptor tyrosine kinase (like c-kit mutation), is necessary to become full-blown leukemia. Low p53 protein expression and insufficient induction of p53 by genotoxic damage might increase the opportunity to obtain additional oncogenic events, since genome guard function of p53 does not work in t(8;21)AML cells.
Leukemia Research 05/2006; 30(4):379-83. · 2.69 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: t(8;21)(q22;q22) is the most frequently observed karyotypic abnormality associated with acute myeloid leukemia (AML), especially in FAB M2. Clinically, this type of AML often shows eosinophilia and has a high complete remission rate with conventional chemotherapy. t(8;21) AML is also frequently associated with additional karyotypic aberrations, such as a loss of the sex chromosome; however, it is unclear whether these aberrations change the biological and clinical characteristics of t(8;21) AML. To investigate this issue, 94 patients with t(8;21) AML were categorized according to their additional karyotypic aberrations, which were detected in more than three cases, and then morphologic features, phenotypes, expression of cytokine receptors, and clinical features were compared to t(8;21) AML without other additional aberrant karyotypes. t(8;21) AML with loss of the sex chromosome and abnormality of chromosome 9 were found in 27 cases (29.3%) and 10 cases (10.6%), respectively; however, no differences were observed from the t(8;21) AML without other additional karyotypes in terms of morphological and phenotypic features. There was also no significant difference in the clinical outcome among these three groups. On the other hand, trisomy 4 was found in three cases (3.2%) and these cells showed low expressions of CD19 (P=0.06) and IL-7 receptor (P=0.05), and high expressions of CD33 (P=0.13), CD18 (P=0.03), and CD56 (P=0.03) when compared to t(8;21) AML without additional karyotypes. Moreover, all three t(8;21) AML cases with trisomy 4 did not show eosinophilia in their bone marrow and died within 2.4 years. These observations suggest that additional karyotypic aberration, t(8;21) with trisomy 4 is rare, but it may constitute a distinctive subtype of t(8;21) AML.
[Show abstract][Hide abstract] ABSTRACT: One of major causes of end-stage renal disease is glomerulonephritis, the treatment of which remains difficult clinically. It has already been shown that transgenic mice that overexpress brain natriuretic peptide (BNP), with a potent vasorelaxing and natriuretic property, have ameliorated glomerular injury after subtotal nephrectomy. However, the role of natriuretic peptides in immune-mediated renal injury still remains unknown. Therefore, the effects of chronic excess of BNP on anti-glomerular basement membrane nephritis induced in BNP-transgenic mice (BNP-Tg) were investigated and the mechanisms how natriuretic peptides act on mesangial cells in vitro were explored. After induction of nephritis, severe albuminuria (approximately 21-fold above baseline), tissue damage, including mesangial expansion and cell proliferation, and functional deterioration developed in nontransgenic littermates. In contrast, BNP-Tg exhibited much milder albuminuria (approximately fourfold above baseline), observed only at the initial phase, and with markedly ameliorated histologic and functional changes. Up-regulation of transforming growth factor-beta (TGF-beta) and monocyte chemoattractant protein-1 (MCP-1), as well as increased phosphorylation of extracellular signal-regulated kinase (ERK), were also significantly inhibited in the kidney of BNP-Tg. In cultured mesangial cells, natriuretic peptides counteracted the effects of angiotensin II with regard to ERK phosphorylation and fibrotic action. Because angiotensin II has been shown to play a pivotal role in the progression of nephritis through induction of TGF-beta and MCP-1 that may be ERK-dependent, the protective effects of BNP are likely to be exerted, at least partly, by antagonizing the renin-angiotensin system locally. The present study opens a possibility of a novel therapeutic potential of natriuretic peptides for treating immune-mediated renal injury.
Journal of the American Society of Nephrology 01/2002; 12(12):2652-63. · 9.47 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Adrenomedullin (AM), a potent vasorelaxing, natriuretic and cell growth-modulating peptide, is thought to act as an autocrine/paracrine regulator in renal glomeruli and tubules. AM receptors comprise the calcitonin receptor-like receptor (CRLR) and a family of receptor-activity-modifying proteins (RAMPs 1-3); however, the pathophysiological role of AM and its receptor system in the kidney remains to be clarified. We examined the regulation of their expression in a rat model of renal injury and found that RAMP1, RAMP2 and CRLR expressions were markedly upregulated upon induction of fibrosis during obstructive nephropathy. Since AM exerts potent antiproliferative effects in various cell types, upregulation of the AM receptor system may play important roles in modulating the progression of renal diseases.
[Show abstract][Hide abstract] ABSTRACT: PGE2 is known to induce uterine contraction by increasing intracellular Ca2+. In the present study, to investigate other functions of PGE2 in human uterus, two EP3 isoforms were isolated by the RT-PCR method using human uterus polyadenylated ribonucleic acid (RNA). These EP3 isoforms, named EP3-V and EP3-VI, are composed of 402 and 393 amino acid residues, respectively, which are unique compared with EP3 isoforms of other species. Their N-terminal 359 amino acid residues are identical to those of previously reported human EP3 isoforms, whereas the two isoforms contained a novel amino acid sequence in their C-terminal tails. The dissociation constant values of EP3-V and EP3-VI for PGE2 were 3.9 and 1.4 nmol/L, respectively, which were consistent with those of previously reported EP3 isoforms. Signaling experiments revealed that M&B28767, an EP3 agonist, not only inhibited forskolin-induced cAMP concentrations, but also activated mitogen-activated protein kinase in Chinese hamster ovary cells stably expressing EP3-V and EP3-VI. These responses were abolished by treatment with pertussis toxin. In addition, M&B28767 increased cAMP concentrations in EP3-VI-expressing cells, whereas it did not in EP3-V-expressing cells. M&B28767 did not stimulate phosphoinositide turnover in EP3-V or EP3-VI-expressing cells. EP3-V and EP3-VI messenger RNAs (mRNAs) were detected abundantly in human uterus, whereas weak, but substantial, bands were detected in the lung and kidney in RT-PCR specific for each mRNA. In situ hybridization revealed EP3-V and EP3-VI mRNAs in the human myometrium, but not in the endometrium. The present study suggests that EP3-V and EP3-VI are possibly involved in the proliferation of cells in human myometrium.
[Show abstract][Hide abstract] ABSTRACT: Brain natriuretic peptide (BNP) is a cardiac hormone produced by the ventricle, and its secretion is markedly increased in heart failure, hypertension, and renal failure. Transgenic mice that overexpress BNP in the liver (BNP-Tg) were recently generated, resulting in low BP. To elucidate the role of BNP in renal pathophysiology, the effect of chronic excess of BNP in transgenic mice on glomerular injury after subtotal nephrectomy induced by resection of the renal poles was examined. After nephrectomy, glomerular cross-sectional areas in control nontransgenic mice markedly increased as compared with those in sham-operated mice (+81 +/- 7%), whereas there was only a modest increase in BNP-Tg (+10 +/- 6%). Expansion of the mesangial area and increase in the intraglomerular cell number were also inhibited in BNP-Tg. Glomerular expressions of transforming growth factor-beta and fibronectin were increased with hypertrophy and were significantly suppressed in BNP-Tg. Furthermore, increases in the urinary albumin excretion and BP were significantly ameliorated in BNP-Tg. Chronic hydralazine treatment in nephrectomized nontransgenic mice failed to inhibit glomerular hypertrophy. These findings indicate that the chronic excess of BNP in mice ameliorates glomerular hypertrophy and mesangial expansion after renal ablation. The results also suggest that the observed effects of natriuretic peptides under reduced renal mass are not due merely to systemic BP reduction and may be therapeutically applicable in various renal diseases.
Journal of the American Society of Nephrology 10/2000; 11(9):1691-701. · 9.47 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We examined the role of prostaglandin (PG) E receptors in the secretion of aldosterone. PGE2 is known to exert its various biological functions by binding to PGE receptors. There are four subtypes of PGE receptors, EP1, EP2, EP3, and EP4. Among the PGE receptors EP2 and EP4 subtypes are coupled to Gs protein and stimulate adenylyl cyclase. In this study, PGE2 caused a dose-dependent increase in aldosterone production from the rat adrenal zona glomerulosa cells in vitro accompanied with an increase in intracellular cAMP concentration. A specific agonist for EP2, butaprost, did not increase the cAMP production or the aldosterone release, suggesting the possibility that EP4 mediates the secretion of aldosterone by PGE2. Northern blot hybridization analysis disclosed that EP4 gene was expressed in the rat adrenal gland but that EP2 gene was not. In situ hybridization revealed that EP4 mRNA is present abundantly in the zona glomerulosa of rat adrenal gland. These findings suggest that the PGE2-EP4 system is involved in the regulation of aldosterone secretion from the rat adrenal gland.
[Show abstract][Hide abstract] ABSTRACT: Cardiac fibrosis, defined as a proliferation of interstitial fibroblasts and biosynthesis of extracellular matrix components in the ventricles of the heart, is a consequence of remodeling processes initiated by pathologic events associated with a variety of cardiovascular disorders, which leads to abnormal myocardial stiffness and, ultimately, ventricular dysfunction. Brain natriuretic peptide (BNP) is a cardiac hormone produced primarily by ventricular myocytes, and its plasma concentrations are markedly elevated in patients with congestive heart failure and acute myocardial infarction. However, its precise functional significance has been undefined. In this paper, we report the generation of mice with targeted disruption of BNP (Nppb(-/-) mice). We observed multifocal fibrotic lesions in the ventricles from Nppb(-/-) mice. No signs of systemic hypertension and ventricular hypertrophy are noted in Nppb(-/-) mice. In response to ventricular pressure overload, focal fibrotic lesions are increased in size and number in Nppb(-/-) mice, whereas no focal fibrotic changes are found in wild-type littermates (Nppb(+/+) mice). This study establishes BNP as a cardiomyocyte-derived antifibrotic factor in vivo and provides evidence for its role as a local regulator of ventricular remodeling.
Proceedings of the National Academy of Sciences 05/2000; 97(8):4239-44. · 9.81 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Prophet of Pit-1 (Prop-1), which is a paired-like homeodomain transcription factor, is capable of binding to sites in an early enhancer of the Pit-1 gene and regulating its expression. As human Pit-1 is expressed considerably in pituitary adenomas, we studied human Prop-1 gene expression in pituitary adenomas. We also sequenced the Prop-1 cDNAs in pituitary adenomas. Human Prop-1 transcript was detected in all pituitary adenomas examined by RT-PCR analysis. The expression of human Prop-1 in pituitary adenomas was confirmed by in situ hybridization in one of the GH-producing adenomas. The sequence analysis of human Prop-1 cDNAs in these pituitary adenomas revealed that there were no mutations except 5 silent nucleic acid substitutions, suggesting that mutations of Prop-1 gene do not represent a frequent mechanism of human pituitary tumorigenesis.
[Show abstract][Hide abstract] ABSTRACT: This study examined which subtype(s) of PGE receptors is involved in the induction of c-fos and c-jun by PGE(2) in MC3T3-E1 cells. We also investigated the possibility that the induction of these genes is involved in the growth and differentiation of this cell line. PGE(2) dose-dependently induced c-fos and c-jun mRNA expressions in MC3T3-E1 cells. Of the PGE analogs, 17-phenyl-omega-trinor PGE(2) (EP(1) agonist) and sulprostone (EP(1)/EP(3) agonist) were far more potent than butaprost (EP(2) agonist) and 11-deoxy PGE(1) (EP(2)/EP(4) agonist) in inducing c-fos and c-jun mRNA expressions. Since MC3T3-E1 cells do not express the EP(3) subtype, these results suggest that PGE(2) induces c-fos and c-jun mRNA expressions through the EP(1) subtype of its receptor. In order to study the functional relevance of these protooncogenes, we then studied the effect of inhibition of their synthesis by the use of antisense oligonucleotide. Alkaline phosphatase (ALP) suppression by 17-phenyl-omega-trinor PGE(2) was reversed by antisense oligonucleotide for either c-fos or c-jun. These results suggest that PGE(2), via the EP(1) subtype of the PGE receptor, negatively modulates the transition from proliferation to the matrix maturation stage through the induction of c-fos and c-jun. However, antisense oligonucleotide for c-fos or c-jun did not alter the prostaglandin G/H synthase-2 mRNA expression induced by EP(1). Thus, it is possible that c-fos and c-jun inductions do not account for all the EP(1)-mediated PGE(2) actions in MC3T3-E1 cells.
Calcified Tissue International 04/2000; 66(3):217-23. · 2.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Klotho protein is a novel beta-glucosidase-like protein produced predominantly in the kidney. The klotho mouse, which genetically lacks klotho gene expression, manifests various systemic phenotypes resembling aging. In the present study we succeeded in isolating a novel human protein structurally related to klotho protein. The protein possesses one beta-glucosidase-like domain and is 42% identical with klotho protein at the amino acid level. Unlike klotho protein, it possesses neither a signal sequence nor a transmembrane domain, suggesting that it is a cytosolic protein, and thus was termed cytosolic beta-glucosidase-like protein-1 (cBGL1). By Northern blot analysis cBGL1 mRNA was expressed most abundantly in the liver, followed by the small intestine, colon, spleen, and kidney. When klotho and cBGL1 gene expression was examined in renal cell carcinoma tissues, both klotho and cBGL1 mRNA levels in tumors were lower than those in nontumor regions, suggesting that renal epithelial cells may lose klotho and cBGL1 gene expression during the course of malignant transformation. In conclusion, we describe the primary structure and gene expression of a novel protein related to klotho protein.
Journal of Molecular Medicine 02/2000; 78(7):389-94. · 4.74 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: High glucose reportedly stimulates prostaglandin (PG) E2 production and DNA synthesis in mesangial cells (MCs). However, the pathophysiological significance of PGE2 in MCs has remained unclear.
The effects of prostanoids on [3H]-thymidine uptake and cAMP production in rat MCs cultured with 5.6 mM glucose, 25 mM glucose, or 5.6 mM glucose supplemented with 19.4 mM mannitol were examined. The gene expression of PGE2 receptor (EP) subtypes in MCs was analyzed with Northern blotting techniques.
Northern blotting indicated EP1 and EP4 gene expression in MCs. EP1 agonists and PGE2 stimulated [3H]-thymidine uptake in MCs. EP1 antagonists dose dependently attenuated high-glucose-induced [3H]-thymidine uptake, which suggests EP1 involvement, by an increase in intracellular Ca2+, in DNA synthesis of MCs. On the other hand, forskolin, db-cAMP, and 11-deoxy-PGE1, an EP4/EP3/EP2 agonist, significantly decreased DNA synthesis in MCs. These inhibitory effects are thought to be mediated via EP4 as a result of an increase in cAMP synthesis. The effects via EP4 seem to be particularly important because PGE2-induced cAMP synthesis was significantly attenuated in the high-glucose group compared with the mannitol group, in which [3H]-thymidine uptake did not increase in spite of augmented PGE2 production.
The increase in DNA synthesis in MCs under high-glucose conditions can be explained, at least in part, by the high-glucose-induced inhibition of cAMP production via EP4, which augments EP1 function in conjunction with the overproduction of PGE2.
Kidney International 09/1999; 56(2):589-600. · 8.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Adrenomedullin(AM) is a potent hypotensive peptide originally isolated from human pheochromocytoma. AM exerts various biological actions such as vasodilation, bronchodilation and natriuresis, by stimulating cAMP production and increasing free Ca2+ levels through the specific receptors. Although an orphan receptor cloned from rat lung, which contained seven transmembrane domains, was proved to be one of the AM receptors, it is now considered by many studies that other receptor subtypes should be present. The precise signal transduction mechanism for the AM receptor is not fully elucidated yet, but it is supposed that AM acts against proliferative changes of vascular and mesangial cells as seen in hypertensive states, at least partly by inhibiting the MAP kinase pathway. Further studies on the AM receptor subtypes and their intracellular signaling mechanisms are needed to clarify the role of AM in various pathophysiological conditions.
Nippon rinsho. Japanese journal of clinical medicine 08/1998; 56(7):1919-24.
[Show abstract][Hide abstract] ABSTRACT: We demonstrated endothelial production of C-type natriuretic peptide (CNP), the third member of the natriuretic peptide family, and its regulation by cytokines, including tumor necrosis factor-alpha (TNF alpha). We thus proposed that CNP can control vascular tone and growth as an endothelium-derived relaxing peptide. We also revealed the marked elevation of plasma CNP concentration in patients with septic shock, in which TNF alpha plays a significant part. As the interaction between endothelial cells (EC) and monocytes-macrophages plays a pivotal role in the pathogenesis of atherosclerosis, we investigated the effect of coculture of EC and macrophages on endothelial production of CNP. We used a human monocytic leukemia cell line, THP-1, which differentiates into macrophages when treated with phorbol 12-myristate 13-acetate. The coculture of EC and THP-1-derived macrophages enhanced CNP secretion by more than 10-fold compared with the single culture of EC or the coculture of EC and THP-1 without phorbol 12-myristate 13-acetate treatment. Prevention of direct contact between EC and THP-1-derived macrophages did not attenuate the increase in CNP secretion. Northern blotting revealed the augmentation of CNP messenger RNA expression in EC in the coculture. We detected TNF alpha in the conditioned medium from the coculture of EC and THP-1-derived macrophages. Furthermore, anti-TNF alpha antibody inhibited the stimulation of CNP secretion in the coculture. CNP at a concentration of 1 nM did not stimulate cGMP production in EC or THP-1-derived macrophages, but it elevated cGMP production significantly in vascular smooth muscle cells. These results indicate that endothelial production of CNP is stimulated mainly by TNF alpha released from THP-1-derived macrophages in the coculture. Endothelial CNP at the enhanced level may be one of the vascular mediators to regulate local vascular tone and growth through cGMP production by vascular smooth muscle cells, suggesting the potential significance of endothelial CNP in atherosclerosis.
[Show abstract][Hide abstract] ABSTRACT: Prostaglandin E2 (PGE2) is known to autoamplify its production in the osteoblasts through the induction of prostaglandin G/H synthase-2 (PGHS-2), which is the inducible form of the rate-limiting enzyme in PG synthesis, PGHS. To elucidate the cellular mechanism mediating this process, we have employed the PGE2 analogs, which are specific agonists for four subtypes of PGE receptor, and studied the potency of these analogs to induce PGHS-2 mRNA in mouse osteoblastic MC3T3-E1 cells. The induction was mainly observed by 17-phenyl-omega-trinor PGE2 (EP1 agonist) and sulprostone (EP3/EP1 agonist), but not by butaprost (EP2 agonist) or 11-deoxy PGE1 (EP4/EP2 agonist). Since EP3 subtype was undetectable in MC3T3-E1 cells, these data indicate that PGHS-2 mRNA induction is mediated through EP1 subtype of PGE receptor in MC3T3-E1 cells. PGE2 production determined by radioimmunoassay was also increased by 17-phenyl-omega-trinor PGE2 and sulprostone. The autoamplification of PGE2 production is considered to be important in elongating the otherwise short-lived PGE2 action in certain physiological conditions such as mechanical stress and fracture healing, as well as the pathological inflammatory bone loss. The observations in the present study provide us with the better understanding of these processes.
Calcified Tissue International 04/1998; 62(4):327-31. · 2.75 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Adrenomedullin (AM), a potent vasorelaxant and natriuretic peptide isolated from human pheochromocytoma, is present in the kidney and secreted from endothelial cells (EC) and vascular smooth muscle cells (VSMC), but the functional role of AM is still unclear. To clarify the significance of AM as a local regulator, we investigated its secretion and action in cultured cells, and examined the effects of neutralization using a specific monoclonal antibody against AM. The prepared antibody directed against the ring structure showed a high affinity for human and rat AM. Using radioimmunoassay with this antibody, we found significant secretion from cultured rat mesangial cells (MC) of a 6-kDa mature form of AM as seen from EC and VSMC. The addition of AM into cultured cells dose-dependently increased cAMP production and potently inhibited PDGF-stimulated thymidine incorporation. Pretreatment with the monoclonal antibody completely abolished cAMP increase induced by exogenous AM. Moreover, antibody neutralization of endogenously secreted AM in cultured EC, but not in MC or VSMC, markedly (by approximately 70%) reduced basal cAMP production and significantly (1.7-fold) enhanced DNA synthesis. These results indicate that AM, acting as an autocrine/paracrine regulator, exerts an antiproliferative action on EC and MC, and suggest its role as a local modulator of endothelial and mesangial function.
Kidney International 04/1998; 53(4):979-85. · 8.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In 227 of 495 (45.9%) Japanese adult patients with acute myelocytic leukemia (AML), leukemic cells expressed CD4. Incidence of CD4 expression in each FAB subtype was as follows: M1 37.4%, M2 33.7%, M3 35.4%, M4 65.0%, and M5 78.3%. The typical expression pattern of myelomonocytic differentiation antigens and cytokine receptors in CD4+ AML was CD34lowCD33high CD11bhighGM-CSFRhigh. AML cases with 11q23 abnormalities and with inv(16) were frequently CD4-positive. These data collectively indicate that CD4 expression in AML cells is associated with monocytic characteristics. However, CD4+CD34high AML cases appear to have unique immature characteristics including low expression of myelomonocytic differentiation antigens (ie CD33 and CD11b), and accumulation of chromosome abnormalities (ie t(8;21) in CD4lowCD34high AML and chromosome 7 abnormalities in CD4highCD34high AML). We speculate that these leukemia subsets originate from CD4+ hematopoietic precursor cells, therefore then should be considered separately from most of the CD4+ AML as represented by CD34lowCD33high CD11bhighGM-CSFRhigh. Overall survival of patients with CD4+ AML in our series was worse than that of those with CD4 AML (P = 0.0202).