Activation of c-Jun N-terminal kinase promotes survival of cardiac myocytes after oxidative stress

Reperfusion injury occurs when ischaemic tissue is reperfused. It involves the generation and release of reactive oxygen that activates numerous signalling pathways and initiates cell death. Exposure of isolated cardiac myocytes to chronic hypoxia followed by reoxygenation results in the early activation of c-Jun N-terminal kinase (JNK) and death by apoptosis of approx. 30% of the myocytes. Although JNK activation has been described in a number of models of ischaemia/reperfusion, the contribution of JNK activation to cell fate has not been established. Here we report that the activation of JNK by reoxygenation correlates with myocyte survival. Transfection of myocytes with JNK pathway interfering plasmid vectors or infection with adenoviral vectors support the hypothesis that JNK is protective. Transfection or infection with JNK inhibitory mutants increased the rates of apoptosis by almost 2-fold compared with control cultures grown aerobically or subjected to hypoxia and reoxygenation. Caspase 9 activity, measured by LEHD cleavage, increased >3-fold during reoxygenation and this activity was enhanced significantly at all times in cultures infected with dominant negative JNK adenovirus. Hypoxia-reoxygenation mediated a biphasic (2.6- and 2.9-fold) activation of p38 mitogen-activated protein kinase, as well as a small increase of tumour necrosis factor alpha (TNFalpha) secretion, but treatments with the p38 MAPK-specific inhibitor SB203580 or saturating levels of a TNFalpha-1 blocking antibody provided only partial protection against apoptosis. The results suggest that JNK activation is protective and that the pathway is largely independent of p38 MAPK or secreted TNFalpha.

Hydrogen peroxide stimulates c-Src-mediated big mitogen-activated protein kinase 1 (BMK1) and the MEF2C signaling pathway in PC12 cells: potential role in cell survival following oxidative insults

Reactive oxygen species, generated by reduction-oxidation (redox) reactions, have been recognized as one of the major mediators of ischemia and reperfusion injury in the brain. Reactive oxygen species-induced cerebral events are attributable, in part, to the change in intracellular signaling molecules including mitogen-activated protein (MAP) kinases. Big MAP kinase 1 (BMK1), also known as ERK5, is a newly identified member of the MAP kinase family and has been reported to be sensitive to oxidative stress. In the present study, we examined the effect of H(2)O(2) on BMK1 activity in PC12 cells, and we investigated the pathophysiological implication of BMK1. Findings showed that BMK1 was rapidly and significantly activated by H(2)O(2) in a concentration-dependent manner in PC12 cells. BMK1 activation by H(2)O(2) was inhibited by both PD98059 and U0126, which were reported to inhibit MEK5 as well as MEK1/2. c-Src was suggested to be involved in BMK1 activation from the experiments with herbimycin A and PP2, specific inhibitors of Src family kinases. Transfection of kinase-inactive Src also inhibited H(2)O(2)-induced BMK1 activation. In addition, H(2)O(2) treatment of cells induced an enhancement of DNA binding activity of MEF2C, a downstream transcription factor of BMK1 in PC12 cells. Finally, pretreatment of cells with PD98059 and U0126 resulted in an increase in cell death including apoptosis by H(2)O(2) in ERK1/2 down-regulated cells as well as in intact PC12 cells. These findings suggest that c-Src mediated BMK1 activation by H(2)O(2) may counteract ischemic cellular damage probably through the activation of MEF2C transcription factor.

Inhibition of metalloproteinases enhances the internalization of anti-CD30 antibody Ki-3 and the cytotoxic activity of Ki-3 immunotoxin

CD30 is selectively expressed on the tumor cells of a variety of malignant disorders of the immune system and can therefore be used as a target for an anti-CD30 antibody-based immunotherapy. However, CD30 is cleaved at the cell surface by tumor necrosis factor-alpha converting enzyme (TACE). This metalloproteinase releases the soluble ectodomain of CD30 (sCD30), which is able to neutralize immunotherapeutic agents before these reach their target cells. Such constitutive CD30 cleavage is enhanced after binding of most anti-CD30 antibodies, leading to a downregulation of CD30 and an increase of sCD30 in the cell environment. Here, we demonstrate that CD30 shedding from the cell line Karpas 299 could effectively be blocked by the hydroxamic acid-based metalloproteinase inhibitors BB-3644 (IC50 = 180 nM), BB-2116 (IC50 = 230 nM), BB-94 (batimastat, IC50 = 230 nM) and BB-2516 (marimastat, IC50 = 1 microM). This inhibition reduced the concentration of sCD30 in the cell environment to the background level, prolonged the persistence of the anti-CD30 antibody Ki-3 on Karpas 299 cells and favored its internalization. Moreover, a nontoxic concentration of the inhibitor BB-3644 significantly increased the cytotoxic activity of the anti-CD30 ricin A-chain immunotoxin Ki-3.dgA towards the CD30(+) Hodgkin-derived cell line L540. Hence, the metalloproteinase inhibitor BB-3644 may be a promising compound to improve the immunotherapy of CD30(+) malignancies.

Sphingosine kinase interacts with TRAF2 and dissects tumor necrosis factor-alpha signaling

Tumor necrosis factor-alpha (TNF) receptor-associated factor 2 (TRAF2) is one of the major mediators of TNF receptor superfamily transducing TNF signaling to various functional targets, including activation of NF-kappa B, JNK, and antiapoptosis. We investigated how TRAF2 mediates differentially the distinct downstream signals. We now report a novel mechanism of TRAF2-mediated signal transduction revealed by an association of TRAF2 with sphingosine kinase (SphK), a lipid kinase that is responsible for the production of sphingosine 1-phosphate. We identified a TRAF2-binding motif of SphK that mediated the interaction between TRAF2 and SphK resulting in the activation of the enzyme, which in turn is required for TRAF2-mediated activation of NF-kappa B but not JNK. In addition, by using a kinase inactive dominant-negative SphK and a mutant SphK that lacks TRAF2-binding motif we show that the interaction of TRAF2 with SphK and subsequent activation of SphK are critical for prevention of apoptosis during TNF stimulation. These findings show a role for SphK in the signal transduction by TRAF2 specifically leading to activation of NF-kappa B and antiapoptosis.

Quantitative structure-activity relationship of some HIV-1 protease inhibitors: a Fujita-Ban type analysis

A Fujita-Ban type analysis has been made on a few series of HIV-1 (human immunodeficiency virus of type 1) protease inhibitors and the activity contributions of various substituents obtained. From these activity contributions, a compound is predicted that may have better activity than ritonavir, presently prescribed for the treatment of patients suffering from HIV-1. A few other compounds are also suggested.

Thrombopoietin regulates Bcl-xL gene expression through Stat5 and phosphatidylinositol 3-kinase activation pathways

Thrombopoietin (TPO), an essential factor for megakaryopoiesis and thrombopoiesis, works as a survival factor for megakaryocytic lineage cells. However, little is known about the molecular mechanism in detail. We show here that TPO supports the survival of TPO-dependent leukemia cell line UT-7/TPO and normal megakaryocytic progenitors via the induction of Bcl-xL, an anti-apoptotic member of the Bcl-2 family. We further analyzed the signal transduction pathways required for TPO-induced Bcl-xL gene expression. A reporter assay with various lengths of Bcl-x gene promoter revealed that both Stat- and nuclear factor kappa B-binding sites are prerequisites for TPO-induced promoter activity. Consistent with these results, TPO induced the binding of Stat5 and subunits of nuclear factor kappa B, p50, and c-Rel to the Bcl-x gene promoter. AG490, a specific inhibitor for Jak2, and LY294002, a specific inhibitor for phosphatidylinositol (PI) 3-kinase, reduced the protein level of Bcl-xL in UT-7/TPO cells, accompanied by an increase in the ratio of apoptotic cells. Interestingly, LY294002 enhanced the TPO-induced DNA binding activity of Stat5 without affecting the Jak2 activation and tyrosine phosphorylation of Stat5. Concomitantly, confocal microscopy revealed that LY294002 clearly inhibited the nuclear export of Stat5, suggesting that PI 3-kinase regulates the subcellular localization of Stat5. Taken together, our results suggest that both Jak-Stat and PI 3-kinase activation pathways regulate the TPO-induced survival of megakaryocytic cells via Bcl-xL gene expression. In addition, our data suggest possible cross-talk between these two signaling pathways.

In vivo reconstitution of Saccharomyces cerevisiae DNA polymerase epsilon in insect cells. Purification and characterization

DNA polymerase epsilon (pol epsilon) is a multiple subunit complex consisting of at least four proteins, including catalytic Pol2p, Dpb2p, Dpb3p, and Dpb4p. Pol epsilon has been shown to play essential roles in chromosomal DNA replication. Here, we report reconstitution of the yeast pol epsilon complex, which was expressed and purified from baculovirus-infected insect cells. During the purification, we were able to resolve the pol epsilon complex and truncated Pol2p (140 kDa), as was observed initially with the pol epsilon purified from yeast. Biochemical characterization of subunit stoichiometry, salt sensitivity, processivity, and stimulation by proliferating cell nuclear antigen indicates that the reconstituted pol epsilon is functionally identical to native pol epsilon purified from yeast and is therefore useful for biochemical characterization of the interactions of pol epsilon with other replication, recombination, and repair proteins. Identification and characterization of a proliferating cell nuclear antigen consensus interaction domain on Pol2p indicates that the motif is dispensable for DNA replication but is important for methyl methanesulfonate damage-induced DNA repair. Analysis of the putative zinc finger domain of Pol2p for zinc binding capacity demonstrates that it binds zinc. Mutations of the conserved cysteines in the putative zinc finger domain reduced zinc binding, indicating that cysteine ligands are directly involved in binding zinc.

Characterization of endocrine gland-derived vascular endothelial growth factor signaling in adrenal cortex capillary endothelial cells

Endocrine gland-derived vascular endothelial growth factor (EG-VEGF) has been recently identified as a mitogen specific for the endothelium of steroidogenic glands. Here we report a characterization of the signal transduction of EG-VEGF in a responsive cell type, bovine adrenal cortex-derived endothelial (ACE) cells. EG-VEGF led to a time- and dose-dependent phosphorylation of p44/42 MAPK. This effect was blocked by pretreatment with pertussis toxin, suggesting that G alpha(i) plays an important role in mediating EG-VEGF-induced activation of MAPK signaling. The inhibitor of p44/42 MAPK phosphorylation PD 98059 resulted in suppression of both proliferation and migration in response to EG-VEGF. EG-VEGF also increased the phosphorylation of Akt in a phosphatidylinositol 3-kinase-dependent manner. Consistent with such an effect, EG-VEGF was a potent survival factor for ACE cells. We also identified endothelial nitric-oxide synthase as one of the downstream targets of Akt activation. Phosphorylation of endothelial nitric-oxide synthase in ACE cells was stimulated by EG-VEGF with a time course correlated to the Akt phosphorylation. Our data demonstrate that EG-VEGF, possibly through binding to a G-protein coupled receptor, results in the activation of MAPK p44/42 and phosphatidylinositol 3-kinase signaling pathways, leading to proliferation, migration, and survival of responsive endothelial cells.

Trachea enhances neurite regeneration from adult rat nodose ganglia in vitro

Trachea is intensely innervated with vagal afferent nerve fibers, and may play an important role in vagus nerve regeneration after axonal injury caused by trauma and surgical operation. We investigated the effects of tracheal tissue on neuronal cell survival and neurite regeneration in adult rat nodose ganglia (NG) in vitro. Co-culture with trachea significantly increased the average number of neurites regenerated from transected nerve terminals of NG explants, from 73.7 to 154.2 after 3 days, from 68 to 186.7 after 5 days, and from 31 to 101.5 after 7 days in culture. Dissociated NG neurons could continue to survive and extend neurites only in the co-existence with satellite cells in collagen gel. Co-cultured trachea improved the ratios of survival and neurite-bearing cells of NG neurons, from 56.7% and 11.1% to 72.3% and 37.6% after 4 days, and from 41.1% and 20.3% to 56.4% and 47.2% after 7 days in culture, respectively. These results imply that tracheal tissue secretes a factor, which could enhance neuronal cell survival and neurite regeneration in NG in the presence of satellite cells in vitro.

Transduction of cell survival signals by connexin-43 hemichannels

Bisphosphonates, drugs used widely in the treatment of bone diseases, prevent osteoblast and osteocyte apoptosis by a mechanism involving extracellular signal-regulated kinase (ERK) activation. We report herein that hexameric connexin (Cx)-43 hemichannels, but not gap junctions, are the essential transducers of the ERK-activating/anti-apoptotic effects of bisphosphonates. Transfection of Cx-43, but not other Cxs, into Cx-43 naive cells confers de novo responsiveness to the drugs. The signal-transducing property of Cx-43 requires the pore forming as well as the C-terminal domains of the protein, the activation of both Src and ERK kinases, and the SH2 and SH3 domains of Src. This evidence adds Cx-43 to the list of transmembrane proteins capable of transducing survival signals in response to extracellular cues and raises the possibility that it may serve in this capacity for endogenously produced molecules or even other drugs.

Activation of STAT5 triggers proliferation and contributes to anti-apoptotic signalling mediated by the oncogenic Xmrk kinase

Extensive studies of primary tumors and tumor derived cell lines revealed that inappropriate activation of specific STATs (particularly of STAT3 and STAT5) occurs with high frequency in a wide variety of human cancers. We reported recently that the melanoma inducing EGFR-related receptor Xmrk specifically induces constitutive activation of STAT5 in fish melanoma cells. However, little is known about the role of STAT5 in solid tumours in general and its function in melanoma in particular. Recent examinations suggest that activated STAT signalling participates in oncogenesis by stimulating cell proliferation and preventing apoptosis. As an initial approach to understanding the consequences of Xmrk induced STAT5 signalling we used the well characterized pro B-cell line Ba/F3 as a sensitive system to analyse mitogenic as well as anti-apoptotic signalling. We identified STAT5 activation as being involved in both growth and survival signalling triggered by the Xmrk kinase possibly due to STAT5 induced expression of pim-1 and bcl-x. We also found a new mechanism of activation of STAT5 by receptor tyrosine kinases, whereby direct interaction of the receptor kinase domain with the STAT protein in a phosphotyrosine independent way led to activation of STAT5 in terms of DNA binding and target gene expression.

Survival and regeneration of rubrospinal neurons 1 year after spinal cord injury

Scientific interest to find a treatment for spinal cord injuries has led to the development of numerous experimental strategies to promote axonal regeneration across the spinal cord injury site. Although these strategies have been developed in acute injury paradigms and hold promise for individuals with spinal cord injuries in the future, little is known about their applicability for the vast majority of paralyzed individuals whose injury occurred long ago and who are considered to have a chronic injury. Some studies have shown that the effectiveness of these approaches diminishes dramatically within weeks after injury. Here we investigated the regenerative capacity of rat rubrospinal neurons whose axons were cut in the cervical spinal cord 1 year before. Contrary to earlier reports, we found that rubrospinal neurons do not die after axotomy but, rather, they undergo massive atrophy that can be reversed by applying brain-derived neurotrophic factor to the cell bodies in the midbrain. This administration of neurotrophic factor to the cell body resulted in increased expression of growth-associated protein-43 and Talpha1 tubulin, genes thought to be related to axonal regeneration. This treatment promoted the regeneration of these chronically injured rubrospinal axons into peripheral nerve transplants engrafted at the spinal cord injury site. This outcome is a demonstration of the regenerative capacity of spinal cord projection neurons a full year after axotomy.

Androgen sensitivity related proteins in hormone-sensitive and hormone-insensitive prostate cancer cell lines treated by androgen antagonist bicalutamide

Members of the bcl-2 gene family and endogenous inhibitors of cyclin-dependent kinases participate in the regulation of apoptosis and cell cycle in a diverse range of cell types and are implicated in the development of hormone refractory prostate cancer and resistance to anti-cancer therapy. The expression of several of these genes can be regulated by steroid hormones and related agents via their nuclear receptors. However, insufficient information considering the protein expression after the treatment by hormone antagonists is available. The aim of this study was to evaluate the expression of anti- and pro-apoptotic proteins, (Bcl-2, Bax), and to correlate this with the appearance of some nuclear receptors and cell cycle related proteins in androgen sensitive and androgen insensitive prostate cancer cell lines, LNCaP and DU-145, after the treatment by androgen antagonist bicalutamide. Our results revealed that androgen receptor (AR) expression in LNCaP cells decreased, however in DU-145 cells AR slightly increased following anti-androgen treatment. The same agent stimulated expression of p21Waf1/Cip5 and p27Kip1 in LNCaP, as well as in DU-145 cell lines. Bcl-2 level increased slightly in LNCaP cells and, in DU-145 cells was almost undetectable. Bax expression was not changed in LNCaP but significantly decreased in DU-145 cells. Similarly, retinoid X receptor beta (RXRbeta) level was significantly down regulated after 24 hours in DU-145 and also in LNCaP cells after 72 hours. These results confirm that androgen withdrawal therapy employing anti-androgens may elicit different signalling pathways in various types of prostate cancer that may be dependent on AR status and AR sensitivity.

Comparison of two different methods for CD34+ selection and T cell depletion in peripheral blood stem cell grafts--our experiences with CellPro, E rosetting and CliniMACS technique

The aim of this study was to establish a suitable method for in vitro T cell depletion in peripheral blood stem cell grafts for mismatched/haploidentical transplantation in children and adults with severe hematological disorders and for autologous transplantation in patients with autoimmune diseases refractory to conventional immunosuppressive treatment. Two different selection techniques have been used: CD34+ selection using immunoaffinity columns (CellPro Ceprate) followed by T cell depletion by E-rosetting or CD34+ selection using submicroscopic paramagnetic beads (CliniMACS device) with T cell depletion in a one step procedure. The mean purity and recovery of CD34+ cells and efficiency of T cell removal in the final product were compared. From March 1995 to December 1998 we prepared twelve allografts using Cell Pro system for eight children with high-risk hematological malignancies and six autografts for six patients with severe autoimmune diseases. From January 1999 to October 2000 we prepared fifteen allografts using CliniMACS system for ten children with high-risk hematological diseases and inborn metabolic disorders or primary immunodeficiences, five allografts for three adult patients with high-risk hematological malignancies and two autografts for two patients with autoimmune diseases. In allogeneic transplantation the median purity of CD34+ cells in the final products after CellPro and E-rosetting was 85.6% (55.3%-95.7%); median recovery was 24.8% (17%-35%), median transplanted doses of T cells per kilogram of body weight were 0.66x10(4) (0-2.8); in autologous transplantation the median purity of CD34+ was 92.6% (55.6%-96%), median recovery was 28% (22%-46.2%), median transplanted doses of T cells per kilogram of body weight were 0.39x10(4) (0.0-3.6). After CliniMACS technique the median purity of CD34+ cells was 94.87% (69.15%-99%),medianrecoverywas 58% (30%-79.6%), median transplanted doses of T cells per kg of body weight were 0.254x10(4) (0-14.15); in autologous transplantation the median purity of CD34+ was 94% (94%-94%, median recovery was 97.4% (95%-99.8%), median transplanted doses of T cells per kilogram of body weight were 0.87x10(4) (0.49-1.24). We consider both methods of CD34+ selection and T cell depletion suitable for peripheral blood stem cell processing before mismatched hemopoietic stem cell transplantation in patients without identical donor or before autologous transplantation for severe autoimmune diseases. However, magnetic separation using CliniMACS system results in higher levels of purity and recovery with efficient T cell depletion.

Gene transfer into human prostate adenocarcinoma cells with an adenoviral vector: Hyperthermia enhances a double suicide gene expression, cytotoxicity and radiotoxicity

We have previously developed a recombinant adenovirus containing a fusion gene of Escherichia coli cytosine deaminase (CD) and herpes simplex virus type 1 thymidine kinase (HSV-1 TK) controlled by a cytomegalovirus (CMV) enhancer-promoter. This replication-incompetent adenovirus effectively transduced the CD-TK gene into human prostate adenocarcinoma DU-145 or PC-3 cells. Interestingly, heat shock at 41 degrees C for 4 hours elevated the level of CD-TK by approximately 5- to 20-fold at a multiplicity of infection (MOI) of 1. Heat-enhanced expression of CD-TK promoted cytotoxicity by 23-, 9-, or 47-fold in the presence of 50 microg/mL ganciclovir (GCV), 500 microg/mL 5-fluorocytosine (5-FC), or 50 microg/mL GCV+500 microg/mL 5-FC, respectively, at an MOI of 1. Moreover, there was an increase in radiosensitivity when adenovirus-infected cells were heated at 41 degrees C for 4 hours followed by irradiation in the presence of the prodrugs. Virus+heat+1 microg/mL GCV treatment increased radiosensitivity by a dose-modifying factor (DMF) of 2.2, whereas virus+heat+10 microg/mL 5-FC exposure resulted in a DMF of 2.3. Radiosensitization was clearly enhanced as a result of combined prodrug exposure (DMF=4.4). Our results suggest that the efficiency in expression of suicide genes from an adenoviral vector used for cytotoxic anticancer therapy could be improved by combining heat treatment with radiation therapy.

Betulinic acid sensitization of low pH adapted human melanoma cells to hyperthermia

Betulinic acid is a known inducer of apoptosis in human melanoma that is most effective under conditions of low pH. It was hypothesized that betulinic acid, in combination with acute acidification and/or hyperthermia, would induce higher levels of apoptosis and cytotoxicity in low pH-adapted human melanoma cells than in cells grown at pH 7.3. DB-1 human melanoma cells, adapted to a tumour-like growth pH of 6.7, were exposed to hyperthermia (2h at 42 degrees C) and/or betulinic acid (4-10 microg/ml) and compared with cells grown at a physiological pH of 7.3 or after acute acidification from pH 7.3-6.3 or pH 6.7-6.3. Betulinic acid induced higher levels of apoptosis and cytotoxicity in low pH-adapted cells than in cells grown at pH 7.3, as measured by the terminal deoxynucleotidyl transferase (TdT) DNA fragmentation assay (TUNEL), the MTS cell viability assay, and single cell survival. Acute acidification of low pH adapted cells rendered them more susceptible to betulinic acid-induced apoptosis and cytotoxicity. In the presence of hyperthermia at 42 degrees C for 2 h, cells grown at pH 7.3 were not sensitized to heat killing by betulinic acid, whereas cells grown at pH 7.3 and acutely acidified to pH 6.3, cells adapted to growth at pH 6.7 and cells adapted to growth at pH 6.7 and acutely acidified to pH 6.3 were all similarly sensitized to heat killing by betulinic acid, with survival values of 5, 9 and 2%, respectively. It is concluded that betulinic acid may be useful in potentiating the therapeutic efficacy of hyperthermia as a cytotoxic agent in acidotic areas of tumours with minimal effect in normal tissues growing at pH 7.3.

Tissue dispersion and flow cytometry for the cellular analysis of wound healing

Injury induces a flux in the cellular composition of tissues as part of the wound healing response. There is no reliable and rapid method to quantify and characterize the cellular composition of the matrix-rich wound. Our aim was to develop a rapid method to quantify the cellular composition in wounds by tissue dispersion and flow cytometry. Age- and weight-matched mice were wounded on the dorsum using a 1.5 x 1.5 cm2 template, and the wounds were excised at predetermined time points. Tissues were dispersed into single-cell suspensions and labeled with antibodies to cell surfaces and intracellular antigens. Flow cytometry was performed to quantify the percentage of each cell population and cell death. We found that our tissue dispersion protocol resulted in low cell death (4%-6%) and very high yield (80-220 x 10(6) cells/g). Furthermore, cell surfaces and intracellular antigens were preserved to provide accurate identification of the different cell populations. With the appropriate modifications, this protocol is likely to be applicable for the viable retrieval and identification of cells from skin and other collagen-dense tissues.

[In vitro development of murine embryos using different types of microinjections]

We studied the effects of different types of microinjections, such as the mechanical damage to cytoplasmic and nuclear membranes of the zygote and the injection of various gene-engineering constructs or buffer solutions into the cytoplasm or the pronucleus, on the preimplantation of murine embryos (CBA x x C57BL)F1. The survival rate of the embryos was estimated by their capacity to develop in vitro to the blastocyst or hatched blastocyst stages. Puncture of the cytoplasm using a microneedle and injection of buff or foreign DNA did not affect the zygotes capacity for further in vitro development. But, the puncture of the pronucleus and microinjection of gene-engineering constructs or buffer into it reliably decreased the survival rate of embryos, as compared to the control. The differences were found in the capacity of murine zygotes for in vitro development after injection with gene-engineering constructs.

Non-glycosidic iridoids from Cymbaria mongolica

Six non-glycosidic iridoids, i.e. (1R,4S,4aS,7S,7aS)-7-hydroxyl-4-hydroxy- methyl-7-methyl-1-methoxyl-1,4,4a,7a-tetrahydrocyclopenta[e]pyran-3-one (1), (1S,4R,4aS,7S,7aS)-7-hydroxyl-4-hydroxymethyl-7-methyl-1-methoxyl-1,4,4a,7a-tetrahydrocyclopenta[e]pyran-3-one (2), (1R,4R,4aS,7S,7aS)-7-hydroxyl-4-hydroxy-methyl-7-methyl-1-methoxyl-1,4,4a,7a-tetrahydrocyclopenta[e]pyran-3-one (3), (1R, 4R, 4aS, 7aS)-4,7-dihydroxymethyl-1-methoxyl-1,4,4a,7a-tetrahydrocyclopenta-6-ene[e]pyran-3-one (4), (1R, 4R, 4aS, 7aS)-4,7-dihydroxymethyl-1-hydroxyl-1,4,4a, 7a-tetrahydrocyclopenta-6-ene[e]pyran-3-one (5), (1R, 4S, 4aS, 7aS)-4,7-dihydroxy-methyl-1-methoxyl-1,4,4a,7a-tetrahydrocyclopenta-6-ene[e]pyran-3-one (6), as well as five known non-glycosidic iridoids mussaenin A (7), gardendiol (8), isoboonein (9), 4-epi-alyxialactone (10) and rehmaglutin D (11) have been isolated from the Chinese medicinal plant Cymbaria mongolica. Their structures were elucidated by spectroscopic methods. These compounds exhibit significant antitumor and antibacterial activity.

Cellular N-Ras promotes cell survival by downregulation of Jun N-terminal protein kinase and p38

Cellular N-Ras provides a steady-state antiapoptotic signal, at least partially through the regulation of phosphorylated Akt and Bad levels. Fibroblasts lacking c-N-Ras expression are highly sensitive to the induction of apoptosis by a variety of agents. Reduction of pBad and pAkt levels using a phosphatidylinositol 3-kinase inhibitor was not sufficient to sensitize the control cell population to the high level of apoptosis observed in the N-Ras knockout cell lines, suggesting that c-N-Ras provides at least one other antiapoptotic signal. Stimulation of the control cells with apoptotic agents results in a transient increase in Jun N-terminal protein kinase (JNK)/p38 activity that decreased to baseline levels during the time course of the experiments. In all cases, however, sustained JNK/p38 activity was observed in cells lacking c-N-Ras expression. This correlated with sustained levels of phosphorylated MKK4 and MKK3/6, upstream activators of JNK and p38, respectively. Mimicking the sustained activation of JNK in the control cells did result in increasing their sensitivity to apoptotic agents, suggesting that prolonged JNK activity is a proapoptotic event. We also examined the potential downstream c-N-Ras targets that might be involved in regulating the duration of the JNK/p38 signal. Only the RalGDS 37G-N-Ras protein protected the N-Ras knockout cells from apoptosis and restored transient rather than sustained JNK activation. These data suggest that cellular N-Ras provides an antiapoptotic signal through at least two distinct mechanisms, one which regulates steady-state pBad and pAkt levels and one which regulates the duration of JNK/p38 activity following an apoptotic challenge.

Hsp27 regulates podocyte cytoskeletal changes in an in vitro model of podocyte process retraction

Nephrotic syndrome (NS) is characterized by structural changes in the actin-rich foot processes of glomerular podocytes. We previously identified high concentrations of the small heat shock protein hsp27 within podocytes as well as increased glomerular accumulation and phosphorylation of hsp27 in puromycin aminonucleoside (PAN) -induced experimental NS. Here we analyzed murine podocytes stably transfected with hsp27 sense, antisense, and vector control constructs using a newly developed in vitro PAN model system. Cell morphology and the microfilament structure of untreated sense and antisense transfectants were altered compared with controls. Vector cell survival, polymerized actin content, cell area, and hsp27 content increased after 1.25 microg/ml PAN treatment and decreased after 5.0 microg/ml treatment. In contrast, sense cells were unaffected by 1.25 microg/ml PAN treatment whereas antisense cells showed decreases or no changes in all parameters. Treatment of sense cells with 5.0 microg/ml PAN resulted in increased cell survival and cell area whereas antisense cells underwent significant decreases in all parameters. Hsp27 provided dramatic protection against PAN-induced microfilament disruption in sense > vector > antisense cells. We conclude that hsp27 is able to regulate both the morphological and actin cytoskeletal response of podocytes in an in vitro model of podocyte injury.

Effect of different Ti-6Al-4V surface treatments on osteoblasts behaviour

The purpose of the present work was to examine the effect of different Ti-6Al-4V surface treatments on osteoblasts behaviour. Previous work in this laboratory has demonstrated that an ageing treatment reduces metal ion release from this alloy compared to standard passivation procedures. In this study. human osteosarcoma MG-63 were used in short-term in vitro tests to assay for cell viability and cell proliferation at 12, 24 and 72 h while SaOS-2 were used in long-term in vitro tests to assay for osteonectin, osteopontin, osteocalcin gene expression, total protein amount (TP). alkaline phosphatase activity (ALP) and fibronectin production (FN) for 1-4 weeks. Epifluorescence microscopy was used to observe SaOS-2 cell morphology. After 24h, there was no difference in MG-63 cell viability proliferation or in SaOS-2 cell morphology between the different surface treatments. For the long-term tests, the aged Ti-6Al4V induced significantly higher cell proliferation than the control Ti-6Al-4V at 72h. At week 1, no difference in the osteonectin, osteopontin, and osteocalcin gene expression was found between samples. The peak of ALP activity appeared earlier at week 2 for the control surface compared with the passivated and aged surfaces. The early increase in ALP activity for the control sample could be a compensatory effect of decreased osteoblasts proliferation. There was no difference in the expression of FN for the different surface treatments. Our present results showed that the different surface treatments, which induced different metal ion release kinetics and surface properties, influenced the cell proliferation and ALP activity of osteoblast cells. Aluminium ions release kinetics as well as presence of vanadium ions may play a major role in influencing the osteoblasts behaviour in the present study.

Cytotoxicity of low pH dentin-bonding agents in a dentin barrier test in vitro

The reaction of three-dimensional cultures of pulp-derived cells in a dentin barrier test was recorded after exposure to All-Bond 2, Prime & Bond NT, Syntac SC, Syntac Classic, and Prompt L-Pop. The materials were applied on bovine dentin disks in a perfusion chamber, and the experiments were performed with (0.3 ml/h, 2 ml/h) and without perfusion of the pulpal part of the chamber. The cell reaction was recorded (MTT assay) and related to noncytotoxic controls. Bonding agents with low pH did not show any cytotoxicity. Syntac Classic decreased the cell activities to 38% to 72%, depending on different experimental conditions, and was more cytotoxic than Syntac SC. Perfusion (2 ml/h) reduced the cytotoxicity for Syntac Classic and increased cell activities from 52% to 72%. Because low pH bonding agents did not show toxic reactions in this dentin barrier test, pulp damage caused by the tested substance is unlikely if a dentin layer protects the pulp.