RESUMO
Cyclic phosphatidic acid (cPA) is a naturally occurring phospholipid mediator and an analog of the growth factor-like phospholipid lysophosphatidic acid (LPA). cPA has a unique cyclic phosphate ring at the sn-2 and sn-3 positions of its glycerol backbone. We showed before that a metabolically stabilized cPA derivative, 2-carba-cPA, relieved osteoarthritis pathogenesis in vivo and induced hyaluronic acid synthesis in human osteoarthritis synoviocytes in vitro. This study focused on hyaluronic acid synthesis in human fibroblasts, which retain moisture and maintain health in the dermis. We investigated the effects of cPA and LPA on hyaluronic acid synthesis in human fibroblasts (NB1RGB cells). Using particle exclusion and enzyme-linked immunosorbent assays, we found that both cPA and LPA dose-dependently induced hyaluronic acid synthesis. We revealed that the expression of hyaluronan synthase 2 messenger RNA and protein is up-regulated by cPA and LPA treatment time dependently. We then characterized the signaling pathways up-regulating hyaluronic acid synthesis mediated by cPA and LPA in NB1RGB cells. Pharmacological inhibition and reporter gene assays revealed that the activation of the LPA receptor LPAR1, Gi/o protein, phosphatidylinositol-3 kinase (PI3K), extracellular-signal-regulated kinase (ERK), and cyclic adenosine monophosphate response element-binding protein (CREB) but not nuclear factor κB induced hyaluronic acid synthesis by the treatment with cPA and LPA in NB1RGB cells. These results demonstrate for the first time that cPA and LPA induce hyaluronic acid synthesis in human skin fibroblasts mainly through the activation of LPAR1-Gi/o followed by the PI3K, ERK, and CREB signaling pathway.
Assuntos
Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/genética , Fibroblastos/efeitos dos fármacos , Compostos Heterocíclicos com 1 Anel/farmacologia , Ácido Hialurônico/biossíntese , Lisofosfolipídeos/farmacologia , Ácidos Fosfatídicos/farmacologia , Pele/efeitos dos fármacos , Linhagem Celular , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Relação Dose-Resposta a Droga , MAP Quinases Reguladas por Sinal Extracelular/genética , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Fibroblastos/citologia , Fibroblastos/metabolismo , Subunidades alfa Gi-Go de Proteínas de Ligação ao GTP/genética , Subunidades alfa Gi-Go de Proteínas de Ligação ao GTP/metabolismo , Regulação da Expressão Gênica , Glucuronosiltransferase/genética , Glucuronosiltransferase/metabolismo , Humanos , Hialuronan Sintases , Ácido Hialurônico/agonistas , Fosfatidilinositol 3-Quinase/genética , Fosfatidilinositol 3-Quinase/metabolismo , Receptores de Ácidos Lisofosfatídicos/genética , Receptores de Ácidos Lisofosfatídicos/metabolismo , Transdução de Sinais , Pele/citologia , Pele/metabolismoRESUMO
BACKGROUND: Cyclic phosphatidic acid (cPA) is a naturally occurring phospholipid mediator with a unique cyclic phosphate ring at the sn-2 and sn-3 positions of its glycerol backbone. Natural cPA and its chemically stabilized cPA derivative, 2-carba-cPA (2ccPA), inhibit chronic and acute inflammation, and 2ccPA attenuates neuropathic pain. Osteoarthritis (OA) is a degenerative disease frequently associated with symptoms such as inflammation and joint pain. Because 2ccPA has obvious antinociceptive activity, we hypothesized that 2ccPA might relieve the pain caused by OA. We aimed to characterize the effects of 2ccPA on the pathogenesis of OA induced by total meniscectomy in the rabbit knee joint. RESULTS: Intra-articular injection of 2ccPA (twice a week for 42 days) significantly reduced pain and articular swelling. Histopathology showed that 2ccPA suppressed cartilage degeneration in OA. We also examined the effects of 2ccPA on the inflammatory and catabolic responses of human OA synoviocytes and chondrosarcoma SW1353 cells in vitro. 2ccPA stimulated synthesis of hyaluronic acid and suppressed production of the metalloproteinases MMP-1, -3, and -13. However, it had no effect on the production of interleukin (IL)-6, an inflammatory cytokine. The suppressive effect of 2ccPA on MMP-1 and -3 production in synoviocytes and on MMP-13 production in SW1353 cells was not mediated by the lysophosphatidic acid receptor, LPA1 receptor (LPA1R). CONCLUSIONS: Our results suggest that 2ccPA significantly reduces the pain response to OA by inducing hyaluronic acid production and suppressing MMP-1, -3, and -13 production in synoviocytes and chondrocytes.
Assuntos
Anti-Inflamatórios não Esteroides/uso terapêutico , Osteoartrite/tratamento farmacológico , Ácidos Fosfatídicos/uso terapêutico , Animais , Células Cultivadas , Citocinas/genética , Citocinas/metabolismo , Modelos Animais de Doenças , Edema/tratamento farmacológico , Edema/etiologia , Feminino , Seguimentos , Humanos , Isoxazóis/farmacologia , Cápsula Articular/citologia , Masculino , Pessoa de Meia-Idade , Osteoartrite/complicações , Osteoartrite/patologia , Medição da Dor , Propionatos/farmacologia , RNA Mensageiro/metabolismo , Coelhos , Membrana Sinovial/efeitos dos fármacos , Fatores de TempoRESUMO
Ordered nucleosome disassembly and reassembly are required for eukaryotic DNA replication. The facilitates chromatin transcription (FACT) complex, a histone chaperone comprising Spt16 and SSRP1, is involved in DNA replication as well as transcription. FACT associates with the MCM helicase, which is involved in DNA replication initiation and elongation. Although the FACT-MCM complex is reported to regulate DNA replication initiation, its functional role in DNA replication elongation remains elusive. To elucidate the functional role of FACT in replication fork progression during DNA elongation in the cells, we generated and analyzed conditional SSRP1 gene knock-out chicken (Gallus gallus) DT40 cells. SSRP1-depleted cells ceased to grow and exhibited a delay in S-phase cell cycle progression, although SSRP1 depletion did not affect the level of chromatin-bound DNA polymerase α or nucleosome reassembly on daughter strands. The tracking length of newly synthesized DNA, but not origin firing, was reduced in SSRP1-depleted cells, suggesting that the S-phase cell cycle delay is mainly due to the inhibition of replication fork progression rather than to defects in the initiation of DNA replication in these cells. We discuss the mechanisms of how FACT promotes replication fork progression in the cells.
Assuntos
Cromatina/química , Replicação do DNA , Proteínas de Ligação a DNA/metabolismo , Proteínas de Grupo de Alta Mobilidade/metabolismo , Chaperonas de Histonas/química , Transcrição Gênica , Fatores de Elongação da Transcrição/metabolismo , Animais , Ciclo Celular , Galinhas , Epigênese Genética , Citometria de Fluxo/métodos , Histonas/química , Humanos , Chaperonas Moleculares/metabolismo , Nucleossomos/metabolismo , Fase SRESUMO
The facilitates chromatin transcription (FACT) complex affects nuclear DNA transactions in a chromatin context. Though the involvement of FACT in eukaryotic DNA replication has been revealed, a clear understanding of its biochemical behavior during DNA replication still remains elusive. Here, we analyzed the chromatin-binding dynamics of FACT using Xenopus egg extract cell-free system. We found that FACT has at least two distinct chromatin-binding phases: (1) a rapid chromatin-binding phase at the onset of DNA replication that did not involve origin licensing and (2) a second phase of chromatin binding that initiated after origin licensing. Intriguingly, early-binding FACT dissociated from chromatin when DNA replication was blocked by the addition of Cdc6 in the licensed state before origin firing. Cdc6-induced removal of FACT was blocked by the inhibition of origin licensing with geminin, but not by suppressing the activity of DNA polymerases, CDK, or Cdc7. Furthermore, chromatin transfer experiments revealed that impairing the later binding of FACT severely compromises DNA replication activity. Taken together, we propose that even though FACT has rapid chromatin-binding activity, the binding pattern of FACT on chromatin changes after origin licensing, which may contribute to the establishment of its functional link to the DNA replication machinery.
Assuntos
Cromatina/metabolismo , Replicação do DNA , Proteínas de Ligação a DNA/metabolismo , Proteínas de Grupo de Alta Mobilidade/metabolismo , Fatores de Elongação da Transcrição/metabolismo , Animais , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Cromatina/genética , Proteínas de Ligação a DNA/genética , Células Eucarióticas/metabolismo , Feminino , Glutationa Transferase/genética , Glutationa Transferase/metabolismo , Proteínas de Grupo de Alta Mobilidade/genética , Chaperonas de Histonas/genética , Chaperonas de Histonas/metabolismo , Humanos , Immunoblotting , Cinética , Masculino , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Oócitos/metabolismo , Ligação Proteica , Espermatozoides/metabolismo , Fatores de Tempo , Fatores de Elongação da Transcrição/genética , Xenopus laevisRESUMO
BACKGROUND: Cyclic phosphatidic acid (cPA) is a structural analog of lysophosphatidic acid (LPA), but possesses different biological functions, such as the inhibition of autotaxin (ATX), an LPA-synthesizing enzyme. As LPA is a signaling molecule involved in nociception in the peripheral and central systems, cPA is expected to possess analgesic activity. We characterized the effects of cPA and 2-carba-cPA (2ccPA), a chemically stable cPA analog, on acute and chronic pain. RESULTS: (1) The systemic injection of 2ccPA significantly inhibited somato-cardiac and somato-somatic C-reflexes but not the corresponding A-reflexes in anesthetized rats. (2) 2ccPA reduced sensitivity measured as the paw withdrawal response to electrical stimulation applied to the hind paws of mice through the C-fiber, but not Aδ or Aß. (3) In mice, pretreatment with 2ccPA dose-dependently inhibited the second phase of formalin-induced licking and biting responses. (4) In mice, pretreatment and repeated post-treatments with 2ccPA significantly attenuated thermal hyperalgesia and mechanical allodynia following partial ligation of the sciatic nerve. (5) In rats, repeated post-treatments with 2ccPA also significantly attenuated thermal hyperalgesia and mechanical allodynia following chronic sciatic nerve constriction. CONCLUSIONS: Our results suggest that cPA and its stable analog 2ccPA inhibit chronic and acute inflammation-induced C-fiber stimulation, and that the central effects of 2ccPA following repeated treatments attenuate neuropathic pain.
Assuntos
Óxidos P-Cíclicos/farmacologia , Lisofosfolipídeos/farmacologia , Nociceptores/efeitos dos fármacos , Nociceptores/patologia , Dor/patologia , Ácidos Fosfatídicos/farmacologia , Doença Aguda , Anestesia , Animais , Comportamento Animal/efeitos dos fármacos , Doença Crônica , Óxidos P-Cíclicos/administração & dosagem , Óxidos P-Cíclicos/química , Modelos Animais de Doenças , Estimulação Elétrica , Formaldeído , Hiperalgesia/complicações , Hiperalgesia/patologia , Hiperalgesia/fisiopatologia , Técnicas In Vitro , Injeções Intravenosas , Lisofosfolipídeos/administração & dosagem , Lisofosfolipídeos/química , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Nociceptores/metabolismo , Dor/complicações , Dor/fisiopatologia , Ácidos Fosfatídicos/administração & dosagem , Ácidos Fosfatídicos/química , Ratos , Ratos Wistar , Reflexo/efeitos dos fármacos , Sistema Nervoso Simpático/efeitos dos fármacos , Sistema Nervoso Simpático/patologia , Sistema Nervoso Simpático/fisiopatologia , TemperaturaRESUMO
A novel telomerase-associated protein was isolated from porcine testis. The 115-kDa protein, purified with telomerase activity, was molecular cloned using human cDNA library, and identified as MOV10. The expression levels of both MOV10 mRNA and MOV10 protein in cancer cells were 2-3 times higher than that of the normal cells, and MOV10 mRNA was highly expressed in human testis and ovary. The anti-MOV10 antibody precipitated the telomerase activity from cancer cell extracts, and inhibited the telomerase activity in vitro. Sf9-expressed MOV10 protein bound to G-rich strand of both single- and double-stranded telomere-sequenced DNA, but not to single C-rich strand. ChIP assay showed the binding of MOV10 to telomere region in vivo. These data suggest that MOV10 is involved in the progression of telomerase-catalyzing reaction via the interaction of telomerase protein and telomere DNA.
Assuntos
RNA Helicases/metabolismo , Telomerase/metabolismo , Telômero/enzimologia , Animais , Clonagem Molecular , DNA/metabolismo , Biblioteca Gênica , Células HeLa , Humanos , Masculino , RNA Helicases/genética , Suínos , Testículo/enzimologiaRESUMO
Mutations in RecQL4 are a causative factor in Rothmund-Thomson syndrome, a human autosomal recessive disorder characterized by premature aging. To study the role of RecQL4, we employed a cell-free experimental system consisting of Xenopus egg extracts. RecQL4 loading onto chromatin was observed regardless of the presence or absence of EcoRI. However, in the absence of EcoRI, RecQL4 loading was suppressed by geminin, an inhibitor of pre-replicative complex formation, while in the presence of EcoRI, it was not affected. These results suggest that under the former condition, RecQL4-loading depended on DNA replication, while under the latter, the interaction occurred in response to double-stranded DNA breaks (DSBs) induced by EcoRI. DSB-induced RecQL4 loading depended on the function of the ataxia-telangiectasia mutated protein, DNA-dependent protein kinase (DNA-PK), and replication protein A, while there were only minor changes in DNA replication-associated RecQL4 loading upon suppression of these proteins. Furthermore, analyses using a chromatin-immunoprecipitation assay and quantification of gammaH2AX after induction of DSBs suggested that RecQL4 is loaded adjacent to Ku heterodimer-binding sites on damaged chromatin, and functions in the repair of DSBs.
Assuntos
Extratos Celulares , Quebras de DNA de Cadeia Dupla , Reparo do DNA , Óvulo/enzimologia , RecQ Helicases/metabolismo , Xenopus/metabolismo , Androstadienos/farmacologia , Animais , Cafeína/farmacologia , Cromatina/metabolismo , Imunoprecipitação da Cromatina , Quebras de DNA de Cadeia Dupla/efeitos dos fármacos , Reparo do DNA/efeitos dos fármacos , Desoxirribonuclease EcoRI/metabolismo , Histonas/metabolismo , Humanos , Óvulo/efeitos dos fármacos , Transporte Proteico/efeitos dos fármacos , Rad51 Recombinase/metabolismo , Proteína de Replicação A/deficiência , Fatores de Tempo , Wortmanina , Proteínas de Xenopus/metabolismoRESUMO
Cyclic phosphatidic acid (1-acyl-sn-glycerol-2,3-cyclic phosphate; cPA) is a naturally occurring analog of lysophosphatidic acid (LPA) with a variety of distinctly different biological activities from those of LPA. In contrast to LPA, a potent inducer of tumor cell invasion, palmitoyl-cPA inhibits FBS- and LPA-induced transcellular migration and metastasis. To prevent the conversion of cPA to LPA we synthesized cPA derivatives by stabilizing the cyclic phosphate ring; to prevent the cleavage of the fatty acid we generated alkyl ether analogs of cPA. Both sets of compounds were tested for inhibitory activity on transcellular tumor cell migration. Carba derivatives, in which the phosphate oxygen was replaced with a methylene group at either the sn-2 or the sn-3 position, showed much more potent inhibitory effects on MM1 tumor cell transcellular migration and the pulmonary metastasis of B16-F0 melanoma than the natural pal-cPA. The antimetastatic effect of carba-cPA was accompanied by the inhibition of RhoA activation and was not due to inhibition of the activation of LPA receptors.
Assuntos
Antineoplásicos/farmacologia , Movimento Celular/efeitos dos fármacos , Neoplasias Pulmonares/prevenção & controle , Lisofosfolipídeos/farmacologia , Melanoma/tratamento farmacológico , Ácidos Fosfatídicos/farmacologia , Animais , Antineoplásicos/síntese química , Antineoplásicos/química , Linhagem Celular Tumoral , Ativação Enzimática/efeitos dos fármacos , Humanos , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/mortalidade , Neoplasias Pulmonares/secundário , Lisofosfolipídeos/síntese química , Lisofosfolipídeos/química , Melanoma/metabolismo , Melanoma/patologia , Camundongos , Metástase Neoplásica , Ácidos Fosfatídicos/síntese química , Ácidos Fosfatídicos/química , Ratos , Ensaios Antitumorais Modelo de Xenoenxerto , Proteína rhoA de Ligação ao GTP/antagonistas & inibidoresRESUMO
In the chicken immune system, gene conversion, a type of homologous recombination, primarily contributes to diversification of the immunoglobulin gene. Here, we report on the rapid generation of specific monoclonal antibodies using the chicken DT40 B-cell line undergoing gene conversion. We discovered that the gene conversion frequency at the immunoglobulin locus is increased by treating DT40 cells with a histone deacetylase inhibitor, trichostatin A (TSA), thereby generating diversity at the immunoglobulin locus in the majority of treated cells. This indicates that TSA treatment accelerates the autonomous diversification of surface IgMs on DT40 cells. We took advantage of this effect to select DT40 cells producing specific antibodies with antigen-conjugated magnetic beads. This autonomously diversifying library (ADLib) selection system enables the quick establishment (approximately 1 week from a diversifying library) of various clones producing monoclonal IgMs with enough specificity and affinity for immunological assays, and is applicable to various biotechnologies including rational protein design.
Assuntos
Fragmentos de Imunoglobulinas/genética , Imunoglobulina M/genética , Recombinação Genética , Animais , Especificidade de Anticorpos , Reações Antígeno-Anticorpo , Linfócitos B/imunologia , Linhagem Celular , Ácidos Cicloexanocarboxílicos/imunologia , Rearranjo Gênico do Linfócito B , Inibidores de Histona Desacetilases , Ácidos Hidroxâmicos/farmacologia , Magnetismo , Ovalbumina/imunologia , Estreptavidina/imunologia , Transformação GenéticaRESUMO
Cyclic phosphatidic acid (cPA) is a simple lipid containing a fatty acid attached at the sn-1 position and a cyclic phosphate ring structure at the sn-2 and sn-3 positions of the glycerol backbone. The pharmacological effects of cPA have been demonstrated in several diseases such as cancer and neuropathic pain; however, the composition of the molecular species of cPA in relative to other lipid species in biological samples is still unclear. Recently, hydrophilic interaction liquid chromatography (HILIC) has demonstrated the ability to perform lipidomic analyses of biological samples. In the present study, we developed the quantitative measurement of cPA and its related lipid species, such as lysophosphatidic acid (LPA) and lysophosphatidylcholine (LPC), in rat serum using HILIC equipped with tandem-mass spectrometry (MS/MS). The lipid analysis using HILIC-MS/MS system demonstrated high linearity and reproducibility. The modified Bligh and Dyer method using citric acid was showed high efficiency on the extraction of cPA and LPA without contamination of artificial products. In rat serum, cPA and LPC contained more saturated fatty acids such as palmitic acid and stearic acid than unsaturated fatty acids, whereas LPA and phosphatidylcholine more contained unsaturated fatty acids than saturated fatty acids. The analytical methods for measuring cPA and its related lipid species in the present study will aid the analysis of their metabolism.
Assuntos
Cromatografia Líquida/métodos , Interações Hidrofóbicas e Hidrofílicas , Ácidos Fosfatídicos/sangue , Espectrometria de Massas em Tandem/métodos , Animais , Ácido Cítrico/química , Ácido Clorídrico/química , Lisofosfolipídeos/sangue , Masculino , Fosfatidilcolinas/sangue , Ratos Wistar , Padrões de Referência , Reprodutibilidade dos TestesRESUMO
Lysophosphatidic acid (LPA) and cyclic phosphatidic acid (cPA) are one of the lipid mediators regulating cell proliferation and differentiation through the activation of LPA receptors. An LPA receptor-mediated signal is important for the development of the central nervous system, while it has been demonstrated that LPA caused microglial activation and astroglial dysfunction. Previously, we have reported that cPA and carba analog of cPA, 2-O-carba-cPA (2ccPA), protected neural damage caused by transient ischemia. However, little is known about the target cell of cPA/2ccPA in the central nervous systems. Here, we examined the effect of 2ccPA on glial proliferation and differentiation using the primary astrocytes and oligodendrocyte precursor cells (OPCs) cultures. 2ccPA increased the DNA synthesis of astrocytes and OPCs, but it did not reduce the formazan production in the mitochondria. Further, 2ccPA increased the cell number and cell survival against oxidative stress. The inhibition of LPA receptors by ki16425 abolished 2ccPA-induced DNA synthesis. Extracellular signal-regulated kinase (ERK) was activated by 2ccPA, which contributed to the astroglial DNA synthesis. These results suggest that 2ccPA is a beneficial regulator of glial population through the activation of LPA receptor without reduction of mitochondrial activity.
Assuntos
Astrócitos/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Células Precursoras de Oligodendrócitos/efeitos dos fármacos , Ácidos Fosfatídicos/administração & dosagem , Receptores de Ácidos Lisofosfatídicos/metabolismo , Animais , Astrócitos/metabolismo , Células Cultivadas , Lisofosfolipídeos/administração & dosagem , Camundongos Endogâmicos ICR , Mitocôndrias/metabolismo , Células Precursoras de Oligodendrócitos/metabolismo , RNA Mensageiro/metabolismo , Transdução de Sinais/efeitos dos fármacosRESUMO
A novel bioactive lipid, cyclic phosphatidic acid (cPA), was isolated originally from myxoamoebae of a true slime mold, Physarum polycephalum, and has now been detected in a wide range of organisms from slime molds to humans. It has a cyclic phosphate at the sn-2 and sn-3 positions of the glycerol carbons, and this structure is absolutely necessary for its activities. This substance shows specific biological functions, including antimitogenic regulation of the cell cycle, regulation of actin stress fiber formation and rearrangement, inhibition of cancer cell invasion and metastasis, regulation of differentiation and viability of neuronal cells, and mobilization of intracellular calcium. Although the structure of cPA is similar to that of lysophosphatidic acid (LPA), its biological activities are apparently distinct from those of LPA. In the present review, we focus mainly on the enzymatic formation of cPA, the antimitogenic regulation of the cell cycle, the inhibition of cancer cell invasion and metastasis, and the neurotrophic effect of cPA.
Assuntos
Ácidos Fosfatídicos/fisiologia , Animais , Encéfalo/fisiologia , Ciclo Celular/fisiologia , Feminino , Humanos , Ácidos Fosfatídicos/isolamento & purificação , Physarum polycephalum/fisiologia , Gravidez , RatosRESUMO
Microtubule-associated protein 4 (MAP4), a major MAP expressed in proliferating non-neuronal cells, consists of an N-terminal projection (PJ) domain and a C-terminal microtubule-binding (MTB) domain. The PJ domain of MAP4 is divided into three regions; the N-terminal acidic region (the Na-region), the multiple KDM-repeated sequence region (the KDM-region), and the b-region followed by the MTB domain. To investigate roles of the PJ domain, we prepared three truncated forms of human MAP4 with different PJ domain lengths; PJ1, PJ2 and MTB with deletion of about one-third, two-third and all of the PJ domain, respectively, and examined their effects on bundle formation of microtubules (MTs). MTs polymerized by full length MAP4 were singly distributed as observed by both negative staining electron microscopy and dark field microscopy. MTs with PJ1 were also separated in solution but became pairs when pelleted by centrifugation. PJ2 formed planar two-dimensional bundles consisting of several MTs (the 2D-bundle). MTB induced large bundles of many MTs, tightly packed without space in between (termed the 3D-bundle). To study how the PJ domain decreases the bundle-forming activity of the MTB domain of MAP4, we made three additional deletion-mutants of MAP4, called Na-MTB, KDM-MTB and Na-PJ2. Na-MTB and KDM-MTB, in which the KDM/b-region and both of Na- and b-regions were deleted respectively, were prepared by fusing the Na-region or KDM-region to MTB. Both of Na-MTB and KDM-MTB suppressed the 3D-bundle formation as effectively as PJ2. MTs polymerized with Na-PJ2, the KDM-deletion mutant made by adding the Na-region to PJ2, were singular and did not become bundles. These results indicated that the PJ domain kept individual MTs separated by suppressing the bundle-forming ability of the MTB domain. The suppressive activity of the PJ domain was correlated with the length, but not the amino acid sequence, of the PJ.
Assuntos
Proteínas Associadas aos Microtúbulos/química , Proteínas Associadas aos Microtúbulos/metabolismo , Microtúbulos/metabolismo , Fragmentos de Peptídeos/metabolismo , Animais , Escherichia coli/fisiologia , Humanos , Proteínas Associadas aos Microtúbulos/genética , Microtúbulos/ultraestrutura , Fragmentos de Peptídeos/genética , Ligação Proteica , Estrutura Terciária de ProteínaRESUMO
Cyclic phosphatidic acid (cPA) is a naturally occurring phospholipid mediator with a unique cyclic phosphate ring at the sn-2 and sn-3 positions of its glycerol backbone. We have previously shown that cPA significantly suppresses ischemia-induced delayed neuronal death and the accumulation of glial fibrillary acidic protein in the CA1 region of the rat hippocampus. These results indicated that the systemic administration of cPA can protect hippocampal neurons against ischemia-induced delayed neuronal cell death. In the current study, we investigated the effects of cPA on neuronal cell death caused by hypoxia in vitro and the molecular mechanisms underlying these effects. We used cobalt chloride (CoCl(2)) to expose cells to hypoxic conditions in vitro. Treating mouse neuroblastoma (Neuro2A) cells with CoCl(2) induced nuclear DNA condensation and phosphatidylserine exposure. However, adding cPA led to the suppression of CoCl(2)-induced apoptosis in a cPA dose-dependent manner and attenuated the increase in the Bax/Bcl-2 ratio caused by CoCl(2). Quantitative PCR analysis showed that Neuro2A cells strongly express the LPA(1), LPA(2), and LPA(6), which are G-protein coupled receptors that can be activated by cPA. To date, LPA(1) and LPA(2) have been reported to exhibit antiapoptotic activity. Therefore, to assess the roles of LPA(1) and LPA(2) on cPA-induced neuroprotective functions, Ki16425, a selective LPA(1) and LPA(3) antagonist, was adopted to know the LPA(1) function and siRNA was used to knockdown the expression of LPA(2). On the basis of our results, we propose that cPA-induced protection of Neuro2A cells from CoCl(2)-induced hypoxia damage is mediated via LPA(2).
Assuntos
Apoptose , Hipóxia Celular , Ácidos Fosfatídicos/química , Animais , Apoptose/efeitos dos fármacos , Western Blotting , Linhagem Celular Tumoral , Cobalto/farmacologia , Citometria de Fluxo , Proteína Glial Fibrilar Ácida/metabolismo , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Humanos , Camundongos , Espécies Reativas de Oxigênio/metabolismoRESUMO
Autotaxin (ATX, nucleotide pyrophosphate/phosphodiesterase-2) is an autocrine motility factor initially characterized from A2058 melanoma cell-conditioned medium. ATX is known to contribute to cancer cell survival, growth, and invasion. Recently ATX was shown to be responsible for the lysophospholipase D activity that generates lysophosphatidic acid (LPA). Production of LPA is sufficient to explain the effects of ATX on tumor cells. Cyclic phosphatidic acid (cPA) is a naturally occurring analog of LPA in which the sn-2 hydroxy group forms a 5-membered ring with the sn-3 phosphate. Cellular responses to cPA generally oppose those of LPA despite activation of apparently overlapping receptor populations, suggesting that cPA also activates cellular targets distinct from LPA receptors. cPA has previously been shown to inhibit tumor cell invasion in vitro and cancer cell metastasis in vivo. However, the mechanism governing this effect remains unresolved. Here we show that 3-carba analogs of cPA lack significant agonist activity at LPA receptors yet are potent inhibitors of ATX activity, LPA production, and A2058 melanoma cell invasion in vitro and B16F10 melanoma cell metastasis in vivo.
Assuntos
Antineoplásicos/farmacologia , Complexos Multienzimáticos/química , Ácidos Fosfatídicos/química , Fosfodiesterase I/química , Pirofosfatases/química , Linhagem Celular Tumoral , Meios de Cultivo Condicionados , Humanos , Metabolismo dos Lipídeos , Lisofosfolipídeos/farmacologia , Melanoma/metabolismo , Invasividade Neoplásica , Metástase Neoplásica , Diester Fosfórico Hidrolases , Proteínas Recombinantes/química , Espectrometria de FluorescênciaRESUMO
The response to DNA damage was analyzed using a cell-free system consisting of Xenopus egg extract and demembranated sperm nuclei. In the absence of DNA-damaging agents, detergent-resistant accumulation of replication protein A appeared in nuclei after a 30 minute incubation, and a considerable portion of the replication protein A signals disappeared during a further 30 minute incubation. Similar replication protein A accumulation was observed in the nuclei after a 30 minute incubation in the extract containing camptothecin, whereas a further 30 minute incubation generated discrete replication protein A foci. The addition of camptothecin also induced formation of gamma-H2AX foci, which have been previously shown to localize at sites of DSBs. Analysis of the time course of DNA replication and results obtained using geminin, an inhibitor of licensing for DNA replication, suggest that the discrete replication protein A foci formed in response to camptothecin-induced DNA damage occur in a DNA-replication-dependent manner. When the nuclei were incubated in the extract containing EcoRI, discrete replication protein A foci were observed at 30 minutes as well as at 60 and 90 minutes after incubation, and the focus-formation of replication protein A was not sensitive to geminin. DNA replication was almost completely inhibited in the presence of EcoRI and the inhibition was sensitive to caffeine, an inhibitor of ataxia telangiectasia mutated protein (ATM) and ATM- and Rad3-related protein (ATR). However, the focus-formation of replication protein A in the presence of EcoRI was not influenced by caffeine treatment. EcoRI-induced incorporation of biotin-dUTP into chromatin was observed following geminin-mediated inhibition of DNA replication, suggesting that the incorporation was the result of DNA repair. The biotin-dUTP signal co-localized with replication protein A foci and was not significantly suppressed or stimulated by the addition of caffeine.
Assuntos
Biotina/análogos & derivados , Núcleo Celular/genética , Sistema Livre de Células/metabolismo , Dano ao DNA/genética , Reparo do DNA/genética , Proteínas de Ligação a DNA/biossíntese , Células Eucarióticas/metabolismo , Genes cdc/fisiologia , Proteínas de Xenopus , Animais , Proteínas Mutadas de Ataxia Telangiectasia , Biotina/farmacologia , Cafeína/farmacologia , Camptotecina/farmacologia , Proteínas de Ciclo Celular/antagonistas & inibidores , Proteínas de Ciclo Celular/metabolismo , Proteínas de Ciclo Celular/farmacologia , Extratos Celulares , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/metabolismo , Sistema Livre de Células/efeitos dos fármacos , Dano ao DNA/efeitos dos fármacos , Reparo do DNA/efeitos dos fármacos , Proteínas de Ligação a DNA/efeitos dos fármacos , Nucleotídeos de Desoxiuracil/farmacologia , Células Eucarióticas/efeitos dos fármacos , Feminino , Geminina , Genes cdc/efeitos dos fármacos , Masculino , Oócitos , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Proteínas Serina-Treonina Quinases/metabolismo , Proteína de Replicação A , DNA Metiltransferases Sítio Específica (Adenina-Específica)/farmacologia , Espermatozoides , Proteínas Supressoras de Tumor , Xenopus laevisRESUMO
A new derivative of 1-phenyl-3-methyl-5-pyrazolone, 4,4-dichloro-1-(2,4-dichlorophenyl)-3-methyl-5-pyrazolone, named TELIN, was chemically synthesized and identified as a potent inhibitor of human telomerase in the cell-free telomeric repeat amplification protocol. TELIN inhibited telomerase activity at submicromolar level with IC50 of approximately 0.3 microM. Kinetic studies revealed that TELIN does not bind to DNA but to telomerase protein, and the mode of inhibition by this substance was competitive-noncompetitive mixed-type with respect to the TS primer, whereas it was uncompetitive or noncompetitive-uncompetitive mixed-type with respect to the three deoxyribonucleosides. These results demonstrate that TELIN is a specific potent catalytic blocker of telomerase,and is considered to be a valuable substance for medical treatment of cancer and related diseases.
Assuntos
Fibroblastos/metabolismo , Leucemia/metabolismo , Pirazóis/química , Pirazóis/metabolismo , Pirazolonas , Telomerase/antagonistas & inibidores , Telomerase/metabolismo , Linhagem Celular , Linhagem Celular Tumoral , Ativação Enzimática , Humanos , CinéticaRESUMO
DNA unwinding factor (DUF) was discovered as an essential DNA replication factor in Xenopus egg extracts. DUF consists of an HMG protein and a homolog of Cdc68p/Spt16p, and has the capability of unwinding dsDNA. Here we have examined the interaction of DUF with chromatin. DUF was incorporated into chromatin assembled from sperm heads and from plasmid DNA in egg extracts. It was revealed that the chromatin assembled in egg extracts immunodepleted of DUF is less sensitive to micrococcal nuclease (NNase) digestion than that assembled in control extracts, indicating that chromatin containing DUF has more decompact structure than that without DUF. Also we found that DUF has a high affinity for core histones in vitro. We suggest that the function of DUF may be to make the chromatin structure accessible to replication factors.
Assuntos
Cromatina/metabolismo , DNA/metabolismo , Proteínas de Grupo de Alta Mobilidade/metabolismo , Nucleossomos/metabolismo , Proteínas de Xenopus/metabolismo , Animais , Cromatografia em Gel , Relação Dose-Resposta a Droga , Feminino , Proteínas de Grupo de Alta Mobilidade/genética , Histonas/metabolismo , Masculino , Nuclease do Micrococo/farmacologia , Óvulo/metabolismo , Ligação Proteica , Espermatozoides/metabolismo , Fatores de Tempo , Xenopus , Proteínas de Xenopus/genéticaRESUMO
The cytoprotective effect of heat shock proteins (HSPs) promises new therapeutic modalities for medical treatment. We examined the anti-ulcer effect of cholesteryl glucoside (1-O-cholesteryl-beta-D-glucopyranoside, CG) on cold-restraint stress-induced gastric ulcer in rats, in terms of its correlative ability to activate heat shock factor (HSF) and to induce HSP70. Rapid induction of CG occurred in animal tissues, especially in stomach, after exposure to stress, indicating that this glycolipid might act as an anti-stress, lipid mediator involved in the very early stages of stress-induced signal transduction. Orally administered CG apparently showed anti-ulcer activity in rats via HSF activation and HSP70 induction. When compared with geranylgeranylacetone (GGA), the well known as an effective, synthetic anti-ulcer agent, CG proved to have the same level of strength on ulcer inhibition. GGA caused CG and HSP70 induction in gastric mucosa, indicating that GGA induced HSP70 via CG production. CG thus might be useful for medical treatment of stress-induced diseases, and as an anti-stress supplement for daily diet.
Assuntos
Antiulcerosos/metabolismo , Colesterol/análogos & derivados , Colesterol/metabolismo , Úlcera Gástrica/metabolismo , Animais , Antiulcerosos/uso terapêutico , Colesterol/uso terapêutico , Diterpenos/metabolismo , Diterpenos/uso terapêutico , Feminino , Proteínas de Choque Térmico HSP70/genética , Proteínas de Choque Térmico HSP70/metabolismo , Estrutura Molecular , Ratos , Ratos Sprague-Dawley , Úlcera Gástrica/tratamento farmacológico , Estresse Psicológico , TemperaturaRESUMO
Histone acetyltransferases (HATs) and ATP-dependent chromatin remodeling factors (ADCRs) are involved in selective gene regulation via modulation of local chromatin configuration. Activation of the recombination hotspot ade6-M26 of Schizosaccharomyces pombe is mediated by a cAMP responsive element (CRE)-like sequence, M26, and a heterodimeric ATF/CREB transcription factor, Atf1.Pcr1. Chromatin remodeling occurs meiotically around M26. We examined the roles of HATs and ADCRs in chromatin remodeling around M26. Histones H3 and H4 around M26 were hyperacetylated in an M26- and Atf1-dependent manner early in meiosis. SpGcn5, the S. pombe homolog of Gcn5p, was required for the majority of histone H3 acetylation around M26 in vivo. Deletion of gcn5+ caused a significant delay in chromatin remodeling but only partial reduction of M26 meiotic recombination frequency. The snf22+ (a Swi2/Snf2-ADCR homologue) deletion and snf22+ gcn5+ double deletion abolished chromatin remodeling and significant reduction of meiotic recombination around M26. These results suggest that HATs and ADCRs cooperatively alter local chromatin structure, as in selective transcription activation, to activate meiotic recombination at M26 in a site-specific manner.