Biomedical subjects

Yuji Yamazaki

Publications and source records attributed to Yuji Yamazaki.

At least 19 recordsLinked to original sources

PubMed2007

Hyperostosis-hyperphosphatemia syndrome: a congenital disorder of O-glycosylation associated with augmented processing of fibroblast growth factor 23.

UNLABELLED: Two hyperphosphatemic patients with mutations in GALNT3 showed low intact FGF23 levels with marked increase of processed C-terminal fragments. FGF23 protein has three O-linked glycans and FGF23 with incomplete glycosylation is susceptible to processing. Silencing GALNT3 resulted in enhanced processing of FGF23. Decreased function of FGF23 by enhanced processing is the cause of hyperphosphatemia in patients with GALNT3 mutation. INTRODUCTION: Hyperostosis-hyperphosphatemia syndrome (HHS) is an autosomal recessive entity manifesting as severe hyperphosphatemia associated with episodic bone pain and radiological findings of cortical hyperostosis and periosteal reaction. Persistent hyperphosphatemia is not counterbalanced by PTH or 1,25-dihydroxyvitamin D, posing a mirror image of hypophosphatemic states attributed to increased fibroblast growth factor (FGF)23 activity. MATERIALS AND METHODS: We describe two children with HHS who were found to be homozygous for a mutation in GALNT3 encoding a peptide involved in mucin-type O-glycosylation (ppGaNTase-T3). FGF23 levels were evaluated by two ELISAs and Western blotting. FGF23 protein was analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Effect of silencing GALNT3 was evaluated using siRNA in cells transfected with expression vector for FGF23. RESULTS: Both patients had low levels of the full-length FGF23 with markedly augmented amounts of the inactive fragments. Biologically active FGF23 has three O-linked glycans. FGF23 with only one or two O-linked glycans is processed into inactive fragments. Decreasing the expression of the GALNT3 gene by RNA interference resulted in enhanced processing of FGF23. CONCLUSIONS: The primary defect in HHS is impairment of glycosylation of FGF23 resulting from mutations in GALNT3 and leading to augmented processing of FGF23. These changes in FGF23 abolish its phosphaturic effect and lead to severe persistent hyperphosphatemia. This study provides the pathogenetic mechanism of the first mucin-type O-glycosylation defect identified.

Amino Acid Sequence↗

PubMed2006

Klotho converts canonical FGF receptor into a specific receptor for FGF23.

FGF23 is a unique member of the fibroblast growth factor (FGF) family because it acts as a hormone that derives from bone and regulates kidney functions, whereas most other family members are thought to regulate various cell functions at a local level. The renotropic activity of circulating FGF23 indicates the possible presence of an FGF23-specific receptor in the kidney. Here we show that a previously undescribed receptor conversion by Klotho, a senescence-related molecule, generates the FGF23 receptor. Using a renal homogenate, we found that Klotho binds to FGF23. Forced expression of Klotho enabled the high-affinity binding of FGF23 to the cell surface and restored the ability of a renal cell line to respond to FGF23 treatment. Moreover, FGF23 incompetence was induced by injecting wild-type mice with an anti-Klotho monoclonal antibody. Thus, Klotho is essential for endogenous FGF23 function. Because Klotho alone seemed to be incapable of intracellular signalling, we searched for other components of the FGF23 receptor and found FGFR1(IIIc), which was directly converted by Klotho into the FGF23 receptor. Thus, the concerted action of Klotho and FGFR1(IIIc) reconstitutes the FGF23 receptor. These findings provide insights into the diversity and specificity of interactions between FGF and FGF receptors.

Animals↗

PubMed2005

A novel mutation in fibroblast growth factor 23 gene as a cause of tumoral calcinosis.

CONTEXT: Tumoral calcinosis is a disease characterized by ectopic calcification and hyperphosphatemia due to enhanced renal tubular phosphate reabsorption. Fibroblast growth factor (FGF)23 was identified as a responsible factor in hypophosphatemic diseases caused by renal phosphate leak. OBJECTIVE: The objective of the study was to analyze the involvement of FGF23 in the development of tumoral calcinosis. DESIGN: Serum FGF23 level was evaluated in a patient with tumoral calcinosis by two kinds of ELISA: full-length assay that detects only full-length FGF23 with phosphate-lowering activity and C-terminal assay that measures full-length as well as C-terminal fragment of FGF23. FGF23 gene was analyzed by direct sequencing of PCR products, and mutant FGF23 was analyzed by Western blotting after expression in mammalian cells. PATIENTS: A family of tumoral calcinosis patients were studied. RESULTS: Serum FGF23 was extremely high when measured by C-terminal assay. In contrast, it was low normal by full-length assay. Analysis of FGF23 gene detected a serine to phenylalanine mutation in codon 129. No wild-type allele of this codon was found in the patient. The brother of the proband showed the same base change. When this mutant FGF23 was expressed in vitro, full-length and N-terminal fragments were barely detectable by Western blotting, whereas C-terminal fragment with the same molecular weight as that from wild-type FGF23 could be detected. CONCLUSION: The production and serum level of C-terminal fragment of FGF23 are increased in this patient with tumoral calcinosis. Together with the recent similar report of FGF23 mutation, impaired action of full-length FGF23 seems to result in tumoral calcinosis.

Adult↗

PubMed2005

Vitamin D receptor-independent FGF23 actions in regulating phosphate and vitamin D metabolism.

FGF23 suppresses both serum phosphate and 1,25-dihydroxyvitamin D [1,25D] levels in vivo. Because 1,25D itself is a potent regulator of phosphate metabolism, it has remained unclear whether FGF23-induced changes in phosphate metabolism were caused by a 1,25D-independent mechanism. To address this issue, we intravenously administered recombinant FGF23 to vitamin D receptor (VDR) null (KO) mice as a rapid bolus injection and evaluated the early effects of FGF23. Administration of recombinant FGF23 further decreased the serum phosphate level in VDR KO mice, accompanied by a reduction in renal sodium-phosphate cotransporter type IIa (NaPi2a) protein abundance and a reduced renal 25-hydroxyvitamin D-1alpha-hydroxylase (1alphaOHase) mRNA level. Thus FGF23-induced changes in NaPi2a and 1alphaOHase expression are independent of the 1,25D/VDR system. However, 24-hydroxylase (24OHase) mRNA expression remained undetectable by the treatment with FGF23. We also analyzed the regulatory mechanism for FGF23 expression. The serum FGF23 level was almost undetectable in VDR KO mice, whereas dietary calcium supplementation significantly increased circulatory levels of FGF23 and its mRNA abundance in bone. This finding indicates that calcium is another determinant of FGF23 production that occurs independently of the VDR-mediated mechanism. In contrast, dietary phosphate supplementation failed to induce FGF23 expression in the absence of VDR, whereas marked elevation in circulatory FGF23 was observed in wild-type mice fed with a high-phosphate diet. Taken together, FGF23 works, at least in part, in a VDR-independent manner, and FGF23 production is also regulated by multiple mechanisms involving VDR-independent pathways.

Animals↗

PubMed2005

Intravenous calcitriol therapy increases serum concentrations of fibroblast growth factor-23 in dialysis patients with secondary hyperparathyroidism.

BACKGROUND/AIMS: Fibroblast growth factor-23 (FGF-23) is a recently discovered phosphaturic factor. Although increased levels of serum FGF-23 have been reported in dialysis patients, the role of high FGF-23 levels remains unclear. Since FGF-23 is associated also with vitamin D metabolism, we examined the changes of serum FGF-23 levels in chronic dialysis patients treated with intravenous calcitriol therapy. METHODS: Thirty patients with severe secondary hyperparathyroidism were treated with intravenous calcitriol (0.5-1.0 microg) two or three times per week for 6 months. The changes of serum levels of calcium, phosphate, intact PTH, and FGF-23 were evaluated. RESULTS: Baseline serum FGF-23 levels were markedly high. By intravenous calcitriol therapy, intact PTH levels decreased effectively in the first month (p < 0.001). In contrast, FGF-23 levels increased gradually during the study period (p = 0.027). The Delta serum FGF-23 level was significantly correlated with the total doses of calcitriol injected intravenously in 6 months in patients with refractory secondary hyperparathyroidism (R2 = 0.147; p = 0.036). CONCLUSIONS: Intravenous calcitriol decreased serum intact PTH level and increased serum FGF-23 levels significantly. Extremely high levels of serum FGF-23 in these patients may be attributed, at least in part, to the cumulative dose of vitamin D.

Calcitriol↗

PubMed2005

Fibroblast growth factor-23 in patients with Graves' disease before and after antithyroid therapy: its important role in serum phosphate regulation.

OBJECTIVE: Hyperthyroidism is a well-described cause of hyperphosphatemia. We aimed to clarify the physiological role of fibroblast growth factor (FGF)-23 in serum phosphate homeostasis in patients with Graves' disease during the course of treatment for hyperthyroidism. CONTEXT: The study group comprised 56 patients (45 for a cross-sectional study and 11 for a longitudinal study) with Graves' disease. For the cross-sectional study, patients were assigned, on the basis of their serum phosphate level, to a hypophosphatemia group (n = 14), a normophosphatemia group (n = 16), or a hyperphosphatemia group (n = 15). Serum FGF-23, calcium, phosphate, PTH, and 1,25-dihydroxyvitamin D [1,25(OH)(2)D] levels were compared between the three groups. For the longitudinal study, we assessed changes in these biochemical indices before and after antithyroid treatment. RESULTS: In the cross-sectional study, the serum FGF-23 level was significantly higher (P < 0.05) in the hyperphosphatemia group than in the other groups (61 +/- 36 ng/liter vs. 31 +/- 22 ng/liter and 30 +/- 9 ng/liter). In the longitudinal study, serum levels of FGF-23 decreased significantly (P < 0.05) from a high of 54 +/- 12 ng/liter before treatment to 29 +/- 14 ng/liter after treatment. In contrast, the serum 1,25(OH)(2)D level increased significantly (P < 0.005) from 55 +/- 22 pmol/liter before treatment to 185 +/- 76 pmol/liter 3 months after treatment. Serum FGF-23 levels were positively correlated with serum phosphate levels (P < 0.0001) and negatively correlated with serum 1,25(OH)(2)D levels (P < 0.0001). CONCLUSIONS: The significant positive correlation between serum levels of phosphate and FGF-23 indicates that FGF-23 may play an important role in serum phosphate homeostasis by its up-regulation in the hyperphosphatemic condition.

Adult↗

PubMed2005

Silver(I) compounds consisting of [2.2]paracyclophane: reversible guest-driven solid-state transformation and incorporation behavior.

Reaction of [2.2]paracyclophane with silver(I) heptafluorobutyrate (AgC3F7CO2) has isolated three novel networks: [Ag4(pcp)(C3F7CO2)4] x pyrene (1), [Ag4(pcp)(C3F7CO2)4] x phen (phen = phenanthrene) (2), and [Ag4(pcp)(C3F7CO2)4] x fluorene (3), and an intercalation compound [Ag4(pcp)(C3F7CO2)4] x 2benzene (4). All the four complexes exhibit two-dimensional (2D) sheet structures in which AgC3F7CO2 form an infinite chain and pcp acts as linkage. 1, 2, and 3 show 2D flat sheets with cavities in which guest molecules are situated, whereas 4 exhibits 2D zigzag layers between which guest benzene molecules are intercalated. Pcp shows mu-di-eta1-eta2 coordination mode in 1, mu-tetra-eta1 coordination mode in 2 and 3, and mu-tetra-eta2 coordination mode in 4. The reversible guest exchanges were observed between complex 1, 2, or 3 and intercalation compound 4. It is unprecedented for metal-organic inclusion complexes that the guest exchange occurs where the guest is the solute molecule. Furthermore, 4 can release the guest, and the original framework was completely recovered after reincorporation of benzene. It should be noted that 4 can incorporate pyrene, phen, and fluorene to give 1, 2, and 3, respectively, after desorption.

Journal Article↗

PubMed2005

Comparison of two assays for fibroblast growth factor (FGF)-23.

FGF-23 was recently shown to be involved in the development of several hypophosphatemic diseases, including X-linked hypophosphatemic rickets/osteomalacia (XLH) and tumor-induced rickets/osteomalacia (TIO). FGF-23 is processed between Arg179 and Ser180, and only full-length FGF-23 was shown to cause hypophosphatemia. Two assays for FGF-23 have been reported. One assay detects only full-length FGF-23. In contrast, the C-terminal assay recognizes both full-length and processed C-terminal fragment of FGF-23. However, discrepant results concerning circulatory levels of FGF-23 in patients with TIO and XLH have been reported using these two assays. We simultaneously measured FGF-23 levels in 13 patients with adult-onset hypophosphatemic osteomalacia and 29 patients with XLH by these two assays. The full-length assay indicated that FGF-23 was above the upper limit of the reference range in all patients with osteomalacia and in 24 of 29 patients with XLH. However, the C-terminal assay in dicated that FGF-23 was within the reference range in 3 of 13 patients with osteomalacia and 16 of 29 patients with XLH. In addition, there was no correlation between FGF-23 levels measured by these assays in patients with XLH whose FGF-23 was within the reference range by C-terminal assay. These results indicate that FGF-23 within the reference range by C-terminal assay does not rule out an increase in full-length FGF-23. In addition, because FGF-23 was high in most of these hypophosphatemic patients, these results support the notion that FGF-23 plays a major role in the development of hypophosphatemia in patients with TIO and XLH.

Adolescent↗

PubMed2004

FGF-23 transgenic mice demonstrate hypophosphatemic rickets with reduced expression of sodium phosphate cotransporter type IIa.

Fibroblast growth factor (FGF)-23 was identified as a causative factor of tumor-induced osteomalacia and also as a responsible gene for autosomal dominant hypophosphatemic rickets. To clarify the pathophysiological roles of FGF-23 in these diseases, we generated its transgenic mice. The transgenic mice expressing human FGF-23 reproduced the common clinical features of these diseases such as hypophosphatemia probably due to increased renal phosphate wasting, inappropriately low serum 1,25-dihydroxyvitamin D level, and rachitic bone. The renal phosphate wasting in the transgenic mice was accompanied by the reduced expression of sodium phosphate cotransporter type IIa in renal proximal tubules. These results reinforce the notion that the excessive action of FGF-23 plays a causative role in the development of several hypophosphatemic rickets/osteomalacia.

Animals↗

PubMed2004

Syntheses, structures, and properties of intercalation compounds of silver(I) complex with [2.2]paracyclophane.

Reaction of [2.2]paracyclophane (pcp) with silver(I) trifluoroacetate (AgCF(3)CO(2)) and silver(I) pentafluoroproprionate (AgC(2)F(5)CO(2)) has led to isolation of three novel intercalation polymers: [Ag(4)(pcp)(CF(3)CO(2))(4)](C(6)H(6)) (1), [Ag(4)(pcp)(CF(3)CO(2))(4)](C(6)H(3)Me(3)) (2), and [Ag(4)(pcp)(C(2)F(5)CO(2))(4)](pcp) (3). Structure studies using single crystal X-ray diffraction have shown that all compounds contain two-dimensional layered frameworks based on cation-pi interactions, in which pcp exhibits an unprecedented micro-tetra-eta(2) coordination mode. Guest molecules which weakly interact with the host pcp via C-H.pi interactions are intercalated between layers. The guest-eliminated complexes (1a and 2a) and guest-reincorporated ones (1b or 1c and 2b or 2c), accompanied by small structural changes, were confirmed by (1)H NMR, thermogravimetric analysis, mass spectra, and X-ray powder diffraction patterns. The structural changes from 1 --> 1a --> 1c (=1) can take place reversibly in the process of exposure of 1a to benzene vapor. The original framework of complex 2 is also completely recovered by immersing 2a in mesitylene as well as exposing it to mesitylene vapor.

Journal Article↗

PubMed2004

Targeted ablation of Fgf23 demonstrates an essential physiological role of FGF23 in phosphate and vitamin D metabolism.

Inorganic phosphate is essential for ECM mineralization and also as a constituent of important molecules in cellular metabolism. Investigations of several hypophosphatemic diseases indicated that a hormone-like molecule probably regulates serum phosphate concentration. FGF23 has recently been recognized as playing important pathophysiological roles in several hypophosphatemic diseases. We present here the evidence that FGF23 is a physiological regulator of serum phosphate and 1,25-dihydroxyvitamin D (1,25[OH]2D) by generating FGF23-null mice. Disruption of the Fgf23 gene did not result in embryonic lethality, although homozygous mice showed severe growth retardation with abnormal bone phenotype and markedly short life span. The Fgf23(-/-) mice displayed significantly high serum phosphate with increased renal phosphate reabsorption. They also showed an elevation in serum 1,25(OH)2D that was due to the enhanced expression of renal 25-hydroxyvitamin D-1alpha-hydroxylase (1alpha-OHase) from 10 days of age. These phenotypes could not be explained by currently known regulators of mineral homeostasis, indicating that FGF23 is essential for normal phosphate and vitamin D metabolism.

Animals↗

PubMed2004

Venous sampling for fibroblast growth factor-23 confirms preoperative diagnosis of tumor-induced osteomalacia.

Tumor-induced osteomalacia (TIO) is a paraneoplastic disorder characterized by hypophosphatemia, phosphaturia, inappropriately low serum levels of 1,25-dihydroxyvitamin D for hypophosphatemia, and skeletal undermineralization. Patients with TIO suffer from severe muscle weakness and pain. Because surgical removal of the responsible tumors is the only satisfactory treatment for TIO, identification of the tumors is clinically essential. However, because they are predominantly slow-growing neoplasms of benign mesenchymal origin, localization of the responsible tumors is often very difficult. Moreover, even if a tumor is found in a patient with hypophosphatemic osteomalacia, we have had no way to know that the tumor is actually causing the disease. Fibroblast growth factor-23 (FGF-23) was recently identified as a causative factor for TIO and was shown to induce renal phosphate wasting. We have recently shown that the circulatory FGF-23 level was high in a patient with TIO and rapidly decreased after removal of the responsible tumor. For the first time, we describe a patient with adult-onset hypophosphatemic osteomalacia in whom a clinical diagnosis of TIO was confirmed before surgical removal of the tumor by localizing the responsible tumor using venous sampling for FGF-23 together with magnetic resonance imaging. This combinatorial procedure would be clinically useful for sporadic cases of hypophosphatemic rickets/osteomalacia.

Abdominal Neoplasms↗

PubMed2004

Fibroblast growth factor (FGF)-23 in patients with primary hyperparathyroidism.

OBJECTIVE: We aimed to determine the serum level of fibroblast growth factor-23 (FGF-23) in patients with primary hyperparathyroidism (pHPT) to understand its physiological role in the disorder. PATIENTS AND METHODS: Ninety-eight patients with pHPT who underwent parathyroidectomy formed the study group. We also measured serum FGF-23 in 11 of these patients on postoperative day 6. RESULTS: Serum FGF-23 levels was significantly higher in pHPT patients than in healthy controls (35.6+/-17.8 ng/l vs 28.9+/-11.2 ng/l (mean+/-s.d.); P<0.001 (Pearson's correlation coefficient)), but there was no significant difference in the serum FGF-23 level between pHPT patients with normal renal function (creatinine clearance (Ccr) of >or=70 ml/min) and healthy controls. Serum FGF-23 correlated positively with serum calcium (P<0.0001) and intact parathyroid hormone (PTH) (P<0.01), and negatively with Ccr (P<0.001), serum phosphate (P<0.05), and serum 1,25-dihydroxyvitamin D (1,25(OH)(2)D) (P<0.05). Multiple linear regression analysis of factors potentially determining serum FGF-23 levels in pHPT patients showed serum calcium (P<0.01) and Ccr (P<0.001) to be significant predictors. The serum levels of FGF-23 did not change after parathyroidectomy despite the normalization of serum calcium values. Multiple linear regression analysis revealed that serum FGF-23 was not a significant predictor of serum phosphate or 1,25(OH)(2)D in pHPT patients. CONCLUSIONS: FGF-23 may not play a significant role in regulating phosphate or 1,25(OH)(2)D in pHPT patients, especially in those with normal renal function. Further studies are warranted to determine the role of FGF-23 in renal insufficiency or failure.

Adult↗

PubMed2003

FGF-23 is a potent regulator of vitamin D metabolism and phosphate homeostasis.

UNLABELLED: We analyzed the effects of an FGF-23 injection in vivo. FGF-23 caused a reduction in serum 1,25-dihydroxyvitamin D by altering the expressions of key enzymes for the vitamin D metabolism followed by hypophosphatemia. This study indicates that FGF-23 is a potent regulator of the vitamin D and phosphate metabolism. INTRODUCTION: The pathophysiological contribution of FGF-23 in hypophosphatemic diseases was supported by animal studies in which the long-term administration of recombinant fibroblast growth factor-23 reproduced hypophosphatemic rickets with a low serum 1,25-dihydroxyvitamin D [1,25(OH)2D] level. However, there is no clear understanding of how FGF-23 causes these changes. MATERIALS AND METHODS: To elucidate the molecular mechanisms of the FGF-23 function, we investigated the short-term effects of a single administration of recombinant FGF-23 in normal and parathyroidectmized animals. RESULTS: An injection of recombinant FGF-23 caused a reduction in serum phosphate and 1,25(OH)2D levels. A decrease in serum phosphate was first observed 9 h after the injection and was accompanied with a reduction in renal mRNA and protein levels for the type IIa sodium-phosphate cotransporter (NaPi-2a). There was no increase in the parathyroid hormone (PTH) level throughout the experiment, and hypophosphatemia was reproduced by FGF-23 in parathyroidectomized rats. Before this hypophosphatemic effect, the serum 1,25(OH)2D level had already descended at 3 h and reached the nadir 9 h after the administration. FGF-23 reduced renal mRNA for 25-hydroxyvitamin D-1alpha-hydroxylase and increased that for 25-hydroxyvitamin D-24-hydroxylase starting at 1 h. In addition, an injection of calcitriol into normal mice increased the serum FGF-23 level within 4 h. CONCLUSIONS: FGF-23 regulates NaPi-2a independently of PTH and the serum 1,25(OH)2D level by controlling renal expressions of key enzymes of the vitamin D metabolism. In conclusion, FGF-23 is a potent regulator of phosphate and vitamin D homeostasis.

Animals↗

PubMed2003

Transcriptional regulation of the cytosolic chaperonin theta subunit gene, Cctq, by Ets domain transcription factors Elk-1, Sap-1a, and Net in the absence of serum response factor.

The chaperonin-containing t-complex polypeptide 1 (CCT) is a molecular chaperone that facilitates protein folding in eukaryotic cytosol, and the expression of CCT is highly dependent on cell growth. We show here that transcription of the gene encoding the theta subunit of mouse CCT, Cctq, is regulated by the ternary complex factors (TCFs), Elk-1, Sap-1a, and Net (Sap-2). Reporter gene assay using HeLa cells indicated that the Cctq gene promoter contains a cis-acting element of the CCGGAAGT sequence (CQE1) at -36 bp. The major CQE1-binding proteins in HeLa cell nuclear extract was recognized by anti-Elk-1 or anti-Sap-1a antibodies in electrophoretic mobility shift assay, and recombinant Elk-1, Sap-1a, or Net specifically recognized CQE1. The CQE1-dependent transcriptional activity in HeLa cells was virtually abolished by overexpression of the DNA binding domains of TCFs. Overexpression of full-length TCFs with Ras indicated that exogenous TCFs can regulate the CQE1-dependent transcription in a Ras-dependent manner. PD98059, an inhibitor of MAPK, significantly repressed the CQE1-dependent transcription. However, no serum response factor was detected by electrophoretic mobility shift assay using the CQE1 element. These results indicate that transcription of the Cctq gene is regulated by TCFs under the control of the Ras/MAPK pathway, probably independently of serum response factor.

Animals↗

PubMed2003

Discoid medial meniscus.

A discoid medial meniscus is an extremely rare anomaly. We present 4 cases of symptomatic discoid medial meniscus. Furthermore, magnetic resonance imaging (MRI) of the unaffected knee was obtained in 3 cases, and 1 patient had bilateral discoid medial menisci as well as a unilateral discoid lateral meniscus proven by MRI. Another patient had bilateral discoid medial menisci. In one of the other 2 cases, an MRI of the unaffected knee was not obtained. However, in the involved knees of both cases, medial and lateral menisci were discoid. The incidence of bilateral discoid medial menisci is unknown. In the past, the diagnosis of a discoid meniscus was made with an arthrogram or at arthrotomy. Therefore, whether some of the unilateral cases reported in the literature might have been bilateral is unknown. The reported prevalence of bilateral discoid medial menisci will probably increase, because when a discoid medial meniscus is encountered currently, an MRI is used to find knee disorders, including in the contralateral knee. Axial multiplanar gradient-recalled-echo imaging could provide images of the discoid meniscus, depicted in its entirety in one section. This would make the recognition of a discoid meniscus simple.

Abnormalities, Multiple↗

PubMed2003

Ki16425, a subtype-selective antagonist for EDG-family lysophosphatidic acid receptors.

Lysophosphatidic acid (LPA) exerts a variety of biological responses through specific receptors: three subtypes of the EDG-family receptors, LPA1, LPA2, and LPA3 (formerly known as EDG-2, EDG-4, and EDG-7, respectively), and LPA4/GPR23, structurally distinct from the EDG-family receptors, have so far been identified. In the present study, we characterized the action mechanisms of 3-(4-[4-([1-(2-chlorophenyl)ethoxy]carbonyl amino)-3-methyl-5-isoxazolyl] benzylsulfanyl) propanoic acid (Ki16425) on the EDG-family LPA receptors. Ki16425 inhibited several responses specific to LPA, depending on the cell types, without any appreciable effect on the responses to other related lipid receptor agonists, including sphingosine 1-phosphate. With the cells overexpressing LPA1, LPA2, or LPA3, we examined the selectivity and mode of inhibition by Ki16425 against the LPA-induced actions and compared them with those of dioctyl glycerol pyrophosphate (DGPP 8:0), a recently identified antagonist for LPA receptors. Ki16425 inhibited the LPA-induced response in the decreasing order of LPA1 >/= LPA3 >> LPA2, whereas DGPP 8:0 preferentially inhibited the LPA3-induced actions. Ki16425 inhibited LPA-induced guanosine 5'-O-(3-thio)triphosphate binding as well as LPA receptor binding to membrane fractions with a same pharmacological specificity as in intact cells. The difference in the inhibition profile of Ki16425 and DGPP 8:0 was exploited for the evaluation of receptor subtypes involved in responses to LPA in A431 cells. Finally, Ki16425 also inhibited LPA-induced long-term responses, including DNA synthesis and cell migration. In conclusion, Ki16425 selectively inhibits LPA receptor-mediated actions, especially through LPA1 and LPA3; therefore, it may be useful in evaluating the role of LPA and its receptor subtypes involved in biological actions.

Animals↗

PubMed2003

Embryonic development of the Pacific lamprey, Entosphenus tridentatus.

Embryonic development of the Pacific lamprey, Entosphenus tridentatus, from Japan is described. Egg sizes averaged 1.249 mm (longest axis) and 1.145 mm (shortest axis), the time required for hatching being 11 days at 18 degrees C, shorter than previously reported for a lower water temperature (19 days at 15 degrees C). Early development in E. tridentatus proceeded at a similar rate to that in other lampreys, in spite of different rearing water temperatures for the latter, indicating possible specific differences in basic developmental rates.

Animals↗