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Nerve growth factor-induced differentiation changes the cellular organization of regulated Peptide release by PC12 cells.

PC12 cells, like endocrine chromaffin cells, undergo neuronal-like differentiation in response to nerve growth factor (NGF). Here we report that this phenotype conversion produces major changes in release of a green fluorescent protein-tagged neuropeptide-hormone. First, the spatial distribution of the releasable pool is altered; peptide release from untreated cells is supported predominantly by membrane-proximal vesicles, whereas a diffuse pool at the ends of processes is used by NGF-treated cells. Second, the time course of release evoked by photolysis of caged Ca(2+) is faster after differentiation. High-resolution measurements suggest that a slow step before membrane fusion dominates the kinetics of release in untreated cells. Finally, the effect of actin microfilament depolymerization on total release is altered by NGF treatment. This implies that the mechanism that limits the size of the releasable pool is altered by phenotype conversion. Therefore, the cellular organization of peptide release is plastic and changes in response to NGF. This flexibility may be used to generate cell-specific release properties.

Actin Cytoskeleton↗

Phosphotyrosine residues in the nerve-growth-factor receptor (Trk-A). Their role in the activation of inositolphospholipid metabolism and protein kinase cascades in phaeochromocytoma (PC12) cells.

PC12 cells, which lack platelet derived-growth-factor (PDGF) receptors, have been stably transfected with a chimaera consisting of the extracellular domain of the beta-PDGF receptor and the intracellular and transmembrane domains of the nerve-growth-factor receptor Trk-A (termed PT-R). Mutation of the Trk-A residue Tyr490 to phenylalanine prevents the association with Shc, while similar mutations at Tyr751 or Tyr785 are reported to prevent interaction of Trk-A with the p85 subunit of inositol phospholipid 3-kinase and phospholipase C-gamma 1, respectively. The strong and sustained activation of p42 and p44 mitogen-activated-protein kinases induced by PDGF-B/B in PC12/PT-R cells was unaffected by mutation of Tyr785 or Tyr751 to phenylalanine, but was smaller and transient after mutation of Tyr490, and almost abolished by the double mutation of Tyr490 and Tyr785. Mutation of Tyr490 reduced by 70% the PDGF-induced increase in inositol phospholipid 3-kinase activity immunoprecipitated from cell extracts with antiphosphotyrosine monoclonal antibodies and greatly suppressed the PDGF-induced increase in the intracellular products of inositol phospholipid 3-kinase, while mutation of Tyr751 or Tyr785 had no effect. Mutation of Tyr785 (but not mutation of Tyr490 or Tyr751) abolished PDGF-stimulated hydrolysis of phosphatidylinositol 4,5-bisphosphate. Mutation of Tyr490, alone or in combination with mutation of Tyr751 and Tyr785, had no effect on the PDGF-induced activation of p70 S6 kinase (p70S6K). However, the activation of p70S6K by PDGF (or nerve growth factor), but not the activation of mitogen-activated-protein kinase, was prevented by two structurally unrelated inhibitors of inositol phospholipid 3-kinase, wortmannin or LY294002. Our results demonstrate the following: (1) the phosphorylation of Tyr490 plays a major role in the activation of inositol phospholipid 3-kinase and formation of 3-phosphorylated inositol lipids and confirm that the phosphorylation of Tyr 785 triggers the activation of phospholipase C-gamma 1 in vivo. (2) Tyr490 phosphorylation (but not inositol phospholipid 3-kinase activation) is also required for strong and sustained activation of mitogen-activated-protein kinase and neuronal differentiation, while the smaller and more transient activation of mitogen-activated-protein kinase, produced by the activation of phospholipase C-gamma 1 is insufficient to trigger the neuronal differentiation of PT-R cells. (3) Inositol phospholipid 3-kinase is required for the activation of p70S6K, but only a small increase in inositol phospholipid 3-kinase activity and the level of 3-phosphorylated inositol lipids is required for maximal p70S6K activation.

Amino Acid Sequence↗

P2 receptor-mediated inhibition of adenylyl cyclase in PC12 cells.

PC12 pheochromocytoma cells have P2 receptors which are coupled to Ca2+ influx and catecholamine release. Previously we reported that ATP stimulated cyclic AMP accumulation at low concentrations up to 100 microM but showed inhibitory effects above this concentration [Yakushi, Y., Watanabe. A.. Murayama, T., Nomura, Y., 1996. Eur. J. Pharmacol. (314) 243-248]. In this study we investigated the characteristics of the inhibitory effects of ATP analogs. In the presence of 10 microM forskolin, an activator of adenylyl cyclase, ATP, adenosine 5'-O-(3-thiotriphosphate) (ATPgammaS), 2',3'-O-(4-benzoyl) benzoyl ATP, 2-methylthio ATP and adenosine 5'-O-(2-thiodiphosphate) inhibited cyclic AMP accumulation in a dose-dependent manner from 100 microM. UTP, alphabeta and betagamma-methylene ATP had no or very limited effects. The relative order of ATP analogs suggests that the ATP receptor appears to be P2Y-like. However, suramin, an antagonist of P2X and P2Y receptors, and reactive blue-2, which inhibited betagamma-methylene ATP-induced cyclic AMP accumulation, did not modify the inhibitory effect of ATPgammaS. Treatment with pertussis toxin, which completely abolished the effect of carbachol, had no effect on the action of ATP over 300 microM. The existence of a new type of ATP receptor-mediated inhibition of adenylyl cyclase is proposed in PC12 cells.

Adenosine Triphosphate↗

A cysteine-rich domain defined by a novel exon in a slo variant in rat adrenal chromaffin cells and PC12 cells.

cDNA libraries from rat chromaffin cells and PC12 cells were screened for homologs to the mouse mSlo gene that encodes a large conductance, calcium (Ca2+)- and voltage-activated potassium channel (BK channel). One Slo variant contained sequence encoding a cysteine-rich, 59-amino acid insert for a previously described site of alternative splicing. This insert is reminiscent of zinc-finger domains. The exon was found in RNA from pancreas, anterior pituitary, cerebellum, and hippocampus. Expression in Xenopus oocytes of a Slo construct containing this exon conferred a -30 to -20 mV shift of the conductance-voltage curve. A previously uncharacterized alternative splice junction near the C-terminal end of Slo was also identified. In contrast to BK channels in rat chromaffin cells, none of the Slo variants exhibited inactivation when expressed in Xenopus oocytes. PCR screening of chromaffin cell RNA failed to reveal a homolog of an accessory beta subunit known to influence Slo channel function. Furthermore, a beta-subunit-dependent Slo channel activator, dehydrosoyasaponin I, was without effect on chromaffin cell BK current. The results argue that an accessory subunit may not be a required component of the native chromaffin cell BK channel.

Adrenal Medulla↗

Melatonin suppression of PC12 cell growth and death.

Melatonin has previously been reported to influence cell differentiation and growth in a number of cell culture systems in vitro. In this paper, we describe the effects of high pharmacological and low physiological concentrations of melatonin on cell growth in rat pheochromocytoma cells (PC12 cells). Melatonin produced a biphasic response with respect to cell growth in PC12 cells. At low concentrations (1-10 nM) melatonin suppressed PC12 cell growth whereas at higher concentration (10 microM) it prevented cell death. Cultures treated with high concentrations of melatonin displayed an increase in cell number and a decreased release of lactic acid dehydrogenase (LDH) into the culture media, indicating that melatonin was enhancing cell survival as opposed to stimulating cell proliferation. Inhibition of cell death by high concentrations of melatonin was both time and concentration-dependent and did not require the continued presence of melatonin throughout the entire time of incubation. These studies suggest melatonin is preventing either apoptosis or programmed cell death. In contrast, concentrations of melatonin (1-10 nM) at or near the binding affinity for the nuclear receptor, RZRbeta, suppressed PC12 cell growth. At these concentrations, melatonin failed to inhibit forskolin-induced cAMP formation and process outgrowth as well as prevent forskolin suppression of cell growth. These data indicate that PC12 cells probably lack functionally active cell surface receptors for melatonin and suggest the interaction of melatonin with the nuclear receptor may be responsible for suppression of PC12 cell growth.

Animals↗

Solubilization and characterization of the 3H-desipramine binding site of rat phaeochromocytoma cells (PC12-cells).

3H-Desipramine binding sites of the plasma membranes of rat phaeochromocytoma cells (PC12-cells) were solubilized with the nonionic detergent digitonin (0.5%). With the method described here, the binding characteristics of the desipramine binding site were essentially unaltered by solubilization. Binding of 3H-desipramine to the solubilized binding site showed the following characteristics: (1) 3H-desipramine bound with high affinity (KD = 16.6 nmol/l) to a single class of noninteracting (Hill-coefficient = 1.01) binding sites; (2) binding was reversible; (3) binding of unlabelled desipramine had the same dissociation constant as had 3H-desipramine; (4) increasing concentrations of sodium- and chloride-ions stimulated the binding of 3H-desipramine; (5) binding was inhibited by various inhibitors and substrates of neuronal uptake of noradrenaline; and (6) inhibition of binding by the optical isomers of cocaine, oxaprotiline, and amphetamine showed marked stereoselectivity (with preference for (-)cocaine, (+)oxaprotiline, and (+)amphetamine). The finding that the binding of 3H-desipramine to the solubilized binding site was dependent on sodium and chloride, as the neuronal uptake of noradrenaline is, and the finding that all substrates of uptake inhibited the binding of 3H-desipramine, is consistant with the view that desipramine binds to the substrate recognition site of the neuronal carrier for noradrenaline.

Animals↗

Regulation by nerve growth factor and protein phosphorylation of Na/K/2Cl cotransport and cell volume in PC12 cells.

PC12 cells possess a bumetanide-sensitive Na/K/2Cl cotransport system similar to that found in other cell types. Between 10-15% of the total 86Rb influx in these cells is mediated by this pathway under normal conditions. The cotransporter has affinities of 16.5 mM for Nao and 0.7 mM for Ko, is absolutely dependent on Clo and is loop diuretic inhibitable (benzmetanide > bumetanide > piretanide > furosemide). The cotransporter can be activated (up to 8-fold) by cell shrinkage or (up to 4-fold) by treatment with the protein phosphatase inhibitors okadaic acid (EC50 approximately 650 nM) or calyculin A (EC50 approximately 8 nM). Cell shrinkage is followed by a bumetanide-sensitive regulatory volume increase as determined in cell sizing experiments. Calyculin A rapidly elevates normal cell volume in a diuretic-inhibitable manner. Cotransport activity and cell volume are also increased by nerve growth factor (NGF) treatment. The effect of NGF on cotransport rate is biphasic, with an initial rapid approximately 2.5-fold increase followed by a prolonged plateau, and is blocked by pretreatment of the cells with K252a (IC50 approximately 30 nM). By contrast, agents that raise cAMP or phorbol esters lead to an inhibition of cotransport, indicating that the NGF effect is not mediated by stimulation of either cAMP-dependent protein kinase or protein kinase C. Long term NGF treatment (> 2 days) leads to neurite formation and a maintained approximately 2-fold increase in cotransport activity. Bumetanide treatment does not affect the ability of cells to extend neurites, nor is the growth rate of cells in normal medium affected by the diuretic. These results suggest that the cotransport system in PC12 cells is acutely regulated by protein phosphorylation and dephosphorylation as well as cell shrinkage and that cotransport activity may be up-regulated during neuronotypic differentiation.

Animals↗

Regulation of alpha3 nicotinic acetylcholine receptor subunit mRNA levels by nerve growth factor and cyclic AMP in PC12 cells.

To investigate the effects of nerve growth factor (NGF) and cyclic AMP (cAMP) on the level of the nicotinic acetylcholine receptor subunit alpha3 mRNA, we used PC12h cells, PC12 cells expressing dominant-negative Ras protein, and the parental PC12 cells. PC12h cells have NGF-responsive tyrosine hydroxylase activity. Expression of dominant-negative Ras protein prevents the signaling through the Ras-mitogen-activated protein kinase cascade. The morphological changes of the parental PC12 cells in response to NGF and 8-(4-chlorophenylthio)adenosine 3',5'-cyclic monophosphate (CPTcAMP), a cell-penetrating cAMP analogue, were similar to those of PC12h cells. NGF up-regulated the alpha3 mRNA level in PC12h cells and down-regulated the alpha3 mRNA level in the parental PC12 cells. Expression of dominant-negative Ras protein and an inhibitor of mitogen-activated protein kinase kinase inhibited the effects of NGF on alpha3 mRNA level. CPTcAMP down-regulated the alpha3 mRNA level in all three PC12 cell lines. An inhibitor of protein kinase A inhibited the CPTcAMP-induced down-regulation of alpha3 mRNA. The alpha3 mRNA down-regulation required prolonged treatment with CPTcAMP even after cAMP response element binding protein phosphorylation was decreased. Membrane depolarization with high K+ had no effect on the alpha3 mRNA level in PC12h cells. Based on these results, we propose that at least two unknown effectors regulate alpha3 mRNA levels in PC12 cells.

Animals↗

Okadaic acid stimulates the activity of the nerve growth factor-sensitive S6 kinase of PC12 cells.

PC12 pheochromocytoma cells contain at least two different and separable kinases that phosphorylate the S6 protein of the ribosomes. The activity of one of these S6 kinases is increased by treatment of the cells with nerve growth factor and of the other by treatment with epidermal growth factor. Okadaic acid increases the activity of the nerve growth factor-sensitive S6 kinase. The data suggest that the nerve growth factor-sensitive S6 kinase is activated by phosphorylation on serine or threonine residues and is inactivated by either phosphatase 1 or phosphatase 2A, probably the latter.

Animals↗

Characterization of small-molecular-mass guanine-nucleotide-binding regulatory proteins in insulin-secreting cells and PC12 cells.

The distribution of ras-related small-molecular-mass guanine-nucleotide-binding regulatory proteins (SMG) of two insulin-secreting cell lines, RINm5F and HIT-T15, and of a catecholamine-secreting cell line, PC12, have been studied using different techniques. About ten such proteins were detected by [32P]GTP binding after two-dimensional gel electrophoresis and transfer to nitrocellulose membranes. In insulin-secreting cells, rho protein(s) that cannot be detected with the GTP-binding technique were identified by ADP ribosylation with Clostridium botulinum C3 exoenzyme. After subcellular fractionation, SMG displayed specific distributions. The insulin-secreting cell line RINm5F and the catecholamine-secreting cell line PC12 expressed a similar set of these proteins with analogous localization. [32P]GTP binding analysis revealed that at least seven SMG were associated with the secretory granule enriched fraction of RINm5F cells and with the fraction containing dense secretory granules from PC12 cells, proteins of 27 (pI 5.4), 23 (pI 6.8) and 25 kDa (pI 6.7) being the most abundant. These proteins were present in a highly purified granule fraction of a solid rat insulinoma. The 23 kDa (pI 6.8) and 25 kDa (pI 6.7) proteins, but not the protein migrating at 27 kDa (pI 5.4), were detected in the corresponding fraction from HIT-T15 cells. A monoclonal antibody directed against smg25A/rab3A recognized the SMG in secretory granules migrating at 25 kDa (pI 6.7) and 27 kDa (pI 5.4). This antibody also revealed the presence of such protein(s) in homogenates of rat pancreatic islets. During stimulation of insulin secretion of either intact or permeabilized cells, there was no detectable redistribution to the cytosol or to the plasma membrane of the major proteins located on secretory granules. In view of the invariable presence of at least two of the SMG in granules of secretory cells, these proteins are good candidates for regulation of hormone secretion.

Adenosine Diphosphate Ribose↗

Manganese-induced rat pheochromocytoma (PC12) cell death is independent of caspase activation.

Manganese (Mn) is an essential mineral that at high concentrations can produce an irreversible syndrome resembling Parkinson's disease. To examine the mechanism by which Mn elicits its toxic response, we have selected the rat pheochromocytoma cells (PC12) as our model system because it possesses much of the biochemical machinery associated with dopaminergic neurons. Mn-induced PC12 cell death is both time and concentration dependent with approximately 50% cell survival at 48 hr in the presence of 0.3 mM Mn. To determine whether oxidative stress contributed to cytotoxicity induced by Mn, lipid peroxidation was assessed in Mn-treated in PC12 cells. The highly sensitive HPLC assay that measures the lipid peroxide product, 9-HODE, was used and results of these experiments demonstrate there was no increase in the lipid peroxidation in cells exposed to 0.3 mM Mn for 24 hr. Mn was found to stimulate the activation of the apoptotic marker proteins, p38 and caspase-3 within the first 24 hr of treatment. The selective inhibitor of caspase-3, DEVD-CHO, and the nonselective caspase inhibitor, Z-VAD-FMK, however, fail to prevent Mn-induced PC12 cell death. Studies were performed to determine the role of mitochondria in initiating or supporting Mn cytotoxicity, because Mn has been reported to cause changes in membrane permeability. Mn caused a decrease in ATP levels in PC12 cells in both a time and concentration dependent manner. We hypothesize that both apoptosis and necrosis contribute to PC12 cell death although the necrotic events prevail even when the apoptotic signaling is inhibited.

Animals↗

Microinjection of the ras oncogene protein into PC12 cells induces morphological differentiation.

To investigate the possible role of ras proteins in the differentiation process signaled by nerve growth factor, we have microinjected the proto-oncogenic and oncogenic (T24) forms of the human H-ras protein into living rat pheochromocytoma cells (PC12). PC12 cells, which have the phenotype of replicating chromaffin-like cells under normal growth conditions, respond to nerve growth factor by differentiating into nonreplicating sympathetic neuron-like cells. Microinjection of the ras oncogene protein promoted the morphological differentiation of PC12 cells into neuron-like cells. In contrast, microinjection of similar amounts of the proto-oncogene form of the ras protein had no apparent effect on PC12 cells. The induction of morphological differentiation by the ras oncogene protein occurred in the absence of nerve growth factor, was dependent on protein synthesis, and was accompanied by cessation of cell division. Treatment of PC12 cells with nerve growth factor or cAMP analogue prior to injection did not alter the phenotypic changes induced by the ras oncogene protein.

Adrenal Gland Neoplasms↗

Differentiation of PC12 cells with nerve growth factor is associated with induction of transin synthesis and release.

We have identified and characterized a calcium-dependent metalloproteinase which is induced in rat pheochromocytoma cells (PC12 cells) during differentiation with nerve growth factor (NGF). Assays of proteolytic activity in media from differentiated PC12 cell cultures revealed a NGF-dependent increase in the activity of a proteinase which has a molecular weight of 62 kDa. Studies using serine, thiol, and metalloproteinase inhibitors demonstrated that the secreted enzyme is a metalloproteinase. Treatment of culture supernatants with aminophenylmercuric acid (APMA), a known activator of metalloproteinases, resulted in a decrease in the molecular weight of the proteinase. Western blot analysis of culture media from NGF-treated PC12 cells using an antibody directed against a synthetic peptide of rat transin identified this metalloproteinase as transin. Treatment of PC12 cells with acidic and basic fibroblast growth factor (FGF) resulted in distinct morphological changes as well as transin release. Incubation with epidermal growth factor (EGF) did not induce transin release. Dexamethasone inhibited the induction of transin release by NGF. 35S-methionine labeling and immunoprecipitation of newly synthesized proteins from culture supernatants confirmed that NGF induced the synthesis of this enzyme 8 hr after NGF treatment. The NGF-dependent induction of transin, a calcium-dependent metalloproteinase which degrades type IV collagen, laminin, and fibronectin suggests that transin may function to degrade the surrounding extracellular matrix during the invasive process of axonal elongation in neuronal development thereby allowing the movement of growth cones and axons toward specific targets.

Animals↗

Glutathione depletion promotes aluminum-mediated cell death of PC12 cells.

Exposure of rat phenochromocytoma cells (PC12 cells) to aluminum maltolate complex, Al(maltol)3, induced a decrease in intracellular glutathione (GSH) concentration, resulting in a facilitated release of lactate dehydrogenase (LDH) from the cell and an increase in trypan blue-stained cells. Similar phenomena were observed as the cells were treated with L-buthione-[S,R]-sulfoximine (BSO) in the presence of Al(maltol)3. On the other hand, treatment of PC 12 cells with BSO alone in the absence of Al(maltol)3 did not affect the cell viability. Pre-treatment of PC12 cells with N-acetylcysteine (NAC) for 30 min before a 48 h-exposure to Al(maltol)3 effectively protected the cells from Al(maltol)3 toxicity by increasing intracellular GSH concentration. NAC also effectively inhibited reactive oxygen species (ROS) generation induced by treatment of the cells with Al(maltol)3. However, several lipophilic radical scavengers such as alpha-tocopherol and 3(2)-tert-butyl-4-hydroxyanisole, and an iron chelator, desferrioxamine, did not prevent Al(maltol)3-mediated ROS production or the decrease of cell viability. Based on these results, we discussed the role of intracellular GSH against the onset of aluminum toxicity in the context of ROS production.

Animals↗

Combined effect of dopamine and MPP+ on membrane permeability in mitochondria and cell viability in PC12 cells.

The present study examined the combined effect of dopamine and 1-methyl-4-phenylpyridinium (MPP(+)) on the membrane permeability in isolated brain mitochondria and on cell viability in PC12 cells. MPP(+) increased effect of dopamine against the swelling, membrane potential, and Ca(2+) transport in isolated mitochondria, which was not inhibited by the addition of antioxidant enzymes (SOD and catalase). Dopamine or MPP(+) caused the decrease in transmembrane potential, increase in reactive oxygen species, depletion of GSH, and cell death in PC12 cells. Antioxidant enzymes reduced each effect of dopamine and MPP(+) against PC12 cells. Co-addition of dopamine and MPP(+) caused the decrease in the transmembrane potential and increase in the formation of reactive oxygen species in PC12 cells, in which they showed an additive effect. Dopamine plus MPP(+)-induced the depletion of GSH and cell death in PC12 cells were not decreased by the addition of antioxidant enzymes, rutin, diethylstilbestrol, and ascorbate. Melanin caused a cell viability loss in PC12 cells. The N-acetylcysteine, N-phenylthiourea, and 5-hydroxyindole decreased the cell death and the formation of dopamine quinone and melanin induced by co-addition of dopamine and MPP(+), whereas deprenyl and chlorgyline did not show an inhibitory effect. The results suggest that co-addition of dopamine and MPP(+) shows an enhancing effect on the change in mitochondrial membrane permeability and cell death, which may be accomplished by toxic quinone and melanin derived from the MPP(+)-stimulated dopamine oxidation.

1-Methyl-4-phenylpyridinium↗

Survival and differentiation within the adult mouse striatum of grafted rat pheochromocytoma cells (PC12) genetically modified to express recombinant beta-NGF.

Rat pheochromocytoma PC12 cells were genetically modified in vitro to express recombinant beta-nerve growth factor (beta-NGF) using a replication-deficient retroviral vector carrying the mouse beta-NGF gene and subsequently implanted into the striatum of a mouse model of Parkinson's disease. The fate of the genetically modified PC12 cells (PC12N.8) was assessed at varying times postimplantation by studying immunoreactivity (IR) to tyrosine hydroxylase (TH) or the rat NGF receptor (NGFR). In vitro, the genetically modified PC12 cells displayed a neuronal morphology in the absence of exogenous NGF which was characterized by extensive neurite outgrowth. In addition, the genetically modified PC12 displayed a catecholaminergic phenotype in vitro as assessed by TH-IR. Following implantation into the striatum, the survival of PC12N.8 cells was limited. Surviving cells could be identified by NGFR-IR, but not by TH-IR. In addition, PC12N.8 cells with a neuronal morphology similar to that observed in vitro were only rarely observed in vivo. No tumors were observed in PC12N.8 graft recipients up to 30 days postimplantation. In contrast, intrastriatal tumors were observed in 50% of the PC12 cell recipients. These data demonstrate that PC12 cells genetically modified in vitro to synthesize beta-NGF do not revert to the mitotic phenotype of the parent PC12 cell line following implantation into the adult striatum, an observation that suggests that these cells may continue to express recombinant beta-NGF in vivo. The data further suggest that the genetically modified PC12 cells lose the catecholaminergic phenotype following implantation into the striatal parenchyma.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Gland Neoplasms↗

Prolonged activation of transcription factor AP-1 during NGF-mediated rescue from apoptotic cell death in PC12 cells.

Rat pheochromocytoma (PC12) cells exhibit apoptotic cell death when deprived of serum and can be rescued by nerve growth factor (NGF). We characterized AP-1 DNA binding activity in PC12 cells after serum deprivation in the presence or absence of NGF or other neurotrophic agents. There was a decline in AP-1 DNA binding activity concomitant with apoptosis in PC12 cells after serum deprivation. Treatment of serum-deprived PC12 with NGF induced persistent AP-1 binding activity that was blocked by the Trk receptor inhibitor K252a. PC12 cells treated with dibutyryl cyclic AMP or insulin also displayed increased AP-1 DNA binding activity. While NGF somewhat increased c-Fos and c-Jun protein levels transiently, it had a more robust and persistent stimulatory effect on Jun B protein levels. AP-1 transcriptional activity increased after NGF, dibutyryl cAMP, or insulin treatment under serum free conditions. Curcumin, which inhibits AP-1 activity, blocked the NGF-mediated rescue. These results would suggest that the rescue of serum-deprived PC12 cells from apoptosis requires increasing endogenous levels of specific Fos/Jun components of AP-1.

Animals↗

Immobilization of Arg-Gly-Asp (RGD) sequence in sugar containing copolymer for culturing of pheochromocytoma (PC12) cells.

A copolymer that included a Gly-Arg-Gly-Asp-Ser (GRGDS) sequence and sugar moieties was synthesized to culture pheochromocytoma cells (PC12). PC12 cells attached to poly(N-p-vinylbenzyl-D-maltonamide-co-6-(p-vinylbenzamido)-hexanoic acid-g-GRGDS) [p(VMA-co-VBGRGDS)]-coated dishes showed greater proliferation than on other polymer-coated surfaces. Enhancement in cell growth correlated with the ability of soluble Arg-Gly-Asp (RGD) to inhibit cell adhesion to surfaces coated with p(VMA-co-VBGRGDS). This method for promoting cell proliferation may be useful for the culturing of anchorage-dependent cells. Furthermore, about 80% greater dopamine secretion from PC12 cells was produced with the p(VMA-co-VBGRGDS) as compared with PC12 cells on unmodified surfaces.

Journal Article↗