101
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Shou W, Aghdasi B, Armstrong DL, Guo Q, Bao S, Charng MJ, Mathews LM, Schneider MD, Hamilton SL, Matzuk MM. Cardiac defects and altered ryanodine receptor function in mice lacking FKBP12. Nature 1998; 391:489-92. [PMID: 9461216 DOI: 10.1038/35146] [Citation(s) in RCA: 308] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
FKBP12, a cis-trans prolyl isomerase that binds the immunosuppressants FK506 and rapamycin, is ubiquitously expressed and interacts with proteins in several intracellular signal transduction systems. Although FKBP12 interacts with the cytoplasmic domains of type I receptors of the transforming growth factor-beta (TGF-beta) superfamily in vitro, the function of FKBP12 in TGF-beta superfamily signalling is controversial. FKBP12 also physically interacts stoichiometrically with multiple intracellular calcium release channels including the tetrameric skeletal muscle ryanodine receptor (RyR1). In contrast, the cardiac ryanodine receptor, RyR2, appears to bind selectively the FKBP12 homologue, FKBP12.6. To define the functions of FKBP12 in vivo, we generated mutant mice deficient in FKBP12 using embryonic stem (ES) cell technology. FKBP12-deficient mice have normal skeletal muscle but have severe dilated cardiomyopathy and ventricular septal defects that mimic a human congenital heart disorder, noncompaction of left ventricular myocardium. About 9% of the mutants exhibit exencephaly secondary to a defect in neural tube closure. Physiological studies demonstrate that FKBP12 is dispensable for TGF-beta-mediated signalling, but modulates the calcium release activity of both skeletal and cardiac ryanodine receptors.
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MESH Headings
- Abnormalities, Multiple/embryology
- Abnormalities, Multiple/etiology
- Abnormalities, Multiple/genetics
- Activins
- Amino Acid Isomerases/deficiency
- Amino Acid Isomerases/genetics
- Amino Acid Isomerases/physiology
- Animals
- Brain/abnormalities
- Brain/embryology
- Cardiomyopathy, Dilated/embryology
- Cardiomyopathy, Dilated/etiology
- Cardiomyopathy, Dilated/genetics
- Carrier Proteins/genetics
- Carrier Proteins/physiology
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/physiology
- Female
- Fetal Death
- Gene Deletion
- Heart Defects, Congenital/embryology
- Heart Defects, Congenital/etiology
- Heart Defects, Congenital/genetics
- Heart Septal Defects/embryology
- Heart Septal Defects/etiology
- Heart Septal Defects/genetics
- Heat-Shock Proteins/genetics
- Heat-Shock Proteins/physiology
- Inhibins/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Muscle, Skeletal/metabolism
- Ryanodine Receptor Calcium Release Channel/metabolism
- Signal Transduction
- Tacrolimus Binding Proteins
- Transforming Growth Factor beta/metabolism
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Affiliation(s)
- W Shou
- Department of Pathology, Baylor College of Medicine, Houston, Texas 77030, USA
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102
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Nozaki H, Tanaka K, Shirai T, Nagata E, Kondo T, Koyama S, Dembo T, Fukuuchi Y. Binding capacity of FK506 binding protein after 2-hour hemispheric ischemia in gerbil brain. Brain Res 1998; 781:1-7. [PMID: 9507046 DOI: 10.1016/s0006-8993(97)01130-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The binding capacity of FK506 binding protein (FKBP) was examined after 2-h hemispheric ischemia in the gerbil brain in order to clarify the precise mechanism of the neuroprotective effects of FK506. Firstly, the FK506 binding was evaluated in vitro in the normal gerbil brain using 1 nM [3H]dihydro-FK506 as a specific ligand. FK506 binding sites were distributed in a rather homogeneous manner, although the greatest binding was noted in the hippocampus CA1. Secondly, Scatchard analysis demonstrated that the binding sites of FK506 could be composed of two components in each brain region. Thirdly, 18 Mongolian gerbils were divided into two groups: an ischemia group (n = 12) and a sham group (n = 6). The right common carotid artery was ligated to induce hemispheric ischemia for 2 h in the ischemia group. The local cerebral blood flow was measured at the end of the experiment by the [14C]iodoantipyrine method. The ligated animals with levels of local cerebral blood flow in the lateral nuclei of the thalamus of less than 50 ml/100 g/min were utilized as the ischemia group (n=6) for further data analysis. No significant differences in FK506 binding between the ischemia and sham groups were observed in any regions. The above data indicate that the binding capacity of FKBP tends to remain normal during 2-h ischemia, suggesting that FK506 may exert its neuroprotective effects through its binding to FKBP in the brain during the early phase of cerebral ischemia.
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Affiliation(s)
- H Nozaki
- Department of Neurology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160, Japan.
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103
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Abstract
FK506 is a new FDA-approved immunosuppressant used for prevention of allograft rejection in, for example, liver and kidney transplantations. FK506 is inactive by itself and requires binding to an FK506 binding protein-12 (FKBP-12), or immunophilin, for activation. In this regard, FK506 is analogous to cyclosporin A, which must bind to its immunophilin (cyclophilin A) to display activity. This FK506-FKBP complex inhibits the activity of the serine/threonine protein phosphatase 2B (calcineurin), the basis for the immunosuppressant action of FK506. The discovery that immunophilins are also present in the nervous system introduces a new level of complexity in the regulation of neuronal function. Two important calcineurin targets in brain are the growth-associated protein GAP-43 and nitric oxide (NO) synthase (NOS). This review focuses on studies showing that systemic administration of FK506 dose-dependently speeds nerve regeneration and functional recovery in rats following a sciatic-nerve crush injury. The effect appears to result from an increased rate of axonal regeneration. The nerve regenerative property of this class of agents is separate from their immunosuppressant action because FK506-related compounds that bind to FKBP-12 but do not inhibit calcineurin are also able to increase nerve regeneration. Thus, FK506's ability to increase nerve regeneration arises via a calcineurin-independent mechanism (i.e., one not involving an increase in GAP-43 phosphorylation). Possible mechanisms of action are discussed in relation to known actions of FKBPs: the interaction of FKBP-12 with two Ca2+ release-channels (the ryanodine and inositol 1,4,5-triphosphate receptors) which is disrupted by FK506, thereby increasing Ca2+ flux; the type 1 receptor for the transforming growth factor-beta (TGF-beta 1), which stimulates nerve growth factor (NGF) synthesis by glial cells, and is a natural ligand for FKBP-12; and the immunophilin FKBP-52/FKBP-59, which has also been identified as a heat-shock protein (HSP-56) and is a component of the nontransformed glucocorticoid receptor. Taken together, studies of FK506 indicate broad functional roles for the immunophilins in the nervous system. Both calcineurin-dependent (e.g., neuroprotection via reduced NO formation) and calcineurin-independent mechanisms (i.e., nerve regeneration) need to be invoked to explain the many different neuronal effects of FK506. This suggests that multiple immunophilins mediate FK506's neuronal effects. Novel, nonimmunosuppressant ligands for FKBPs may represent important new drugs for the treatment of a variety of neurological disorders.
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Affiliation(s)
- B G Gold
- Center for Research on Occupational and Environmental Toxicology, Oregon Health Sciences University, Portland 97201, USA
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104
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Cardoso CM, Rumjanek VM, De Meis L. Uncoupling of Ca2+ transport ATPase in muscle and blood platelets by diacylglycerol analogues and cyclosporin A antagonism. Biochem J 1997; 327 ( Pt 3):795-801. [PMID: 9581558 PMCID: PMC1218859 DOI: 10.1042/bj3270795] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The possibility that diacylglycerol analogues might have a wider spectrum of intracellular targets than the well-known protein kinase C was investigated with vesicles containing the Ca2+-ATPase derived from the dense tubular system in platelets and from the sarcoplasmic reticulum of skeletal muscle. The diacylglycerol analogues PMA and 1-oleoyl-2-acetyl-rac-glycerol (OAG) inhibited Ca2+ accumulation by these vesicles, an effect that was antagonized by cyclosporin A. The inhibitory activity of PMA and OAG resulted from the uncoupling of the Ca2+-ATPase, characterized by a pronounced inhibition of Ca2+ uptake accompanied by a discrete decrease in ATPase activity and by the inhibition of the enzyme's phosphorylation by Pi, leading to both a decrease in ATP synthesis and an enhancement of Ca2+ efflux. The inhibition of Ca2+ uptake by PMA was found to decrease as the Ca2+ concentration in the medium was raised from 0.1 to 10.0 microM. This was observed with muscle, but not with platelet vesicles. In contrast, the ability of cyclosporin A to antagonize the inhibition of Ca2+ uptake by PMA also increased when the Ca2+ concentration in the medium was raised from 0.1 to 10.0 microM, but this was observed with both muscle and platelet vesicles. The fact that phospholipase C activity and products from the inositol metabolism have been described as localized in regions of the sarcoplasmic reticulum where Ca2+-ATPase and Ca2+ channels are found suggests a possible physiological role for these products in the regulation of cytosolic Ca2+ levels.
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Affiliation(s)
- C M Cardoso
- Instituto de Ciências Biomédicas, Departamento de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Cidade Universitária, Ilha do Fundão, 21941-590, Rio de Janeiro, Brazil
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105
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Carreau A, Gueugnon J, Benavides J, Vigé X. Comparative effects of FK-506, rapamycin and cyclosporin A, on the in vitro differentiation of dorsal root ganglia explants and septal cholinergic neurons. Neuropharmacology 1997; 36:1755-62. [PMID: 9517448 DOI: 10.1016/s0028-3908(97)00160-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
There is increasing evidence that immunophilins play a role in neural development and differentiation. We have studied the neurotrophic effects of FK-506, rapamycin and cyclosporin A (CsA) on dorsal root ganglia (DRG) taken from different segmental levels (cervical, thoracic and lumbar/sacral), and on rat embryonic septal cholinergic neurons in culture. At a low concentration (1 nM), FK-506 significantly increased (+83%) the number of neurites of thoracic DRG explants. At a higher concentration (100 nM), it also enhanced the neuritogenesis of thoracic (+100%) and lumbar/sacral (+57%) DRG, but not cervical DRG explants. Rapamycin displayed a converse effect, reducing the development of DRG explants from cervical and thoracic segments (-78% at 1 nM in thoracic DRG). CsA (from 1 to 100 nM) was without effect on DRG neuritogenesis. In contrast to nerve growth factor (NGF), which increased neurite length (+116% at 3 ng/ml), neither FK-506 nor rapamycin affected this parameter.
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Affiliation(s)
- A Carreau
- Synthélabo Recherche, CNS Research Department, Bagneux, France
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106
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Kloke O, Kummer G, Seeber S. Rapamycin antagonizes interleukin-6 mediated growth arrest and differentiation of myeloblastic M1 cells. Immunol Lett 1997; 59:115-9. [PMID: 9373220 DOI: 10.1016/s0165-2478(97)00110-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The immunosuppressant rapamycin is known to be a potent inhibitor of cytokine driven proliferation of T-lymphocytes and other cell types. Here we have examined the effect of rapamycin on the myeloblastic cell line M1 which responds to interleukin-6 (IL-6) with growth arrest and monocytoid differentiation. Single-agent rapamycin led to a retardation of M cell growth. In spite of this intrinsic antiproliferative effect, rapamycin was found to abrogate IL-6 induced growth arrest. Concomitant exposure to rapamycin and IL-6 also reduced the extent of monocytoid differentiation as compared to treatment with IL-6 alone. Excess levels of the FK-506 analogue ascomycin reversed the antagonistic effect of rapamycin on IL-6 mediated growth suppression, suggesting that this biological action of rapamycin is mediated by a rapamycin/immunophilin complex. The findings demonstrate that rapamycin can also act as an antagonist of cytokine induced growth arrest and differentiation.
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Affiliation(s)
- O Kloke
- Department of Internal Medicine, West German Cancer Center Essen, University of Essen Medical School
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107
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Wang JH, Kelly PT. Attenuation of paired-pulse facilitation associated with synaptic potentiation mediated by postsynaptic mechanisms. J Neurophysiol 1997; 78:2707-16. [PMID: 9356420 DOI: 10.1152/jn.1997.78.5.2707] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Attenuation of paired-pulse facilitation associated with synaptic potentiation mediated by postsynaptic mechanisms. J. Neurophysiol. 78: 2707-2716, 1997. The relationship between paired-pulse facilitation (PPF) and synaptic potentiation induced by various protocols and their cellular and molecular mechanisms were examined by extracellular field potential and current- or voltage-clamp recordings at CA1 synapses in rat hippocampal slices. Microelectrodes were used for both intracellular recordings and injections of modulators of calcium (Ca2+) and Ca2+/calmodulin (CaM) signaling pathways into postsynaptic neurons. Basal synaptic transmission was not accompanied by changes in PPF. Tetanic stimulation induced long-term potentiation (LTP) of synaptic transmission and attenuated PPF. Experiments stimulating two independent Schaffer collateral/commisural(S/C) pathways showed that PPF attenuation and tetanus-LTP were pathway specific. Postsynaptic injections of pseudosubstrate inhibitors of CaM-dependent protein kinase II and protein kinase C (CaM-KII/PKC), [Ala286]CaMKII286-302 plus PKC19-31, almost completely attenuated tetanus-LTP and reversed PPF attenuation but did not affect synaptic transmission and PPF under basal conditions. Postsynaptic injections of heparin and dantrolene (inhibitors of IP3 and ryanodine receptors at intracellular Ca2+ stores) prevented tetanus-LTP induction and PPF attenuation. Postsynaptic injections of calcineurin (CaN) inhibitors, CaN autoinhibitory peptide (CaN-AIP) or FK-506, enhanced synaptic transmission and decreased PPF. CaN-inhibited synaptic potentiation and PPF attenuation were unaffected by (-)-a-Amino-5-phosphonopentanoic, but blocked by coinjecting 1, 2-bis(2-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid, heparin plus dantrolene, calmodulin-binding peptide, or [Ala286]CaMKII281-302 plus PKC19-31. PPF attenuation associated with tetanus-LTP or CaN-inhibited synaptic potentiation resulted from smaller increases in the potentiation of the second synaptic responses (R2) compared with the potentiation of the first responses (R1). Our results indicate that PPF attenuation is associated with synaptic potentiation mediated by postsynaptic mechanisms, and postsynaptic Ca2+/CaM signaling pathways play a dual role in synaptic plasticity. CaN activity limits synaptic transmission under basal conditions, whereas the activation of Ca2+-dependent protein kinases enhances synaptic transmission and attenuates PPF at central synapses.
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Affiliation(s)
- J H Wang
- Department of Neurobiology and Anatomy, University of Texas Medical School at Houston, Houston, Texas 77030, USA
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108
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Cameron AM, Nucifora FC, Fung ET, Livingston DJ, Aldape RA, Ross CA, Snyder SH. FKBP12 binds the inositol 1,4,5-trisphosphate receptor at leucine-proline (1400-1401) and anchors calcineurin to this FK506-like domain. J Biol Chem 1997; 272:27582-8. [PMID: 9346894 DOI: 10.1074/jbc.272.44.27582] [Citation(s) in RCA: 161] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The immunophilin FKBP12 is one of the most abundant and conserved proteins in biology. It is the primary receptor for the immunosuppressant actions of the drug FK506 in whose presence FKBP12 binds to and inhibits calcineurin, disrupting interleukin formation in lymphocytes. The physiologic functions of FKBP12 are less clear, although the protein has been demonstrated to physiologically interact with the inositol 1,4,5-trisphosphate receptor (IP3R), the ryanodine receptor, and the type 1 transforming growth factor beta receptor. We now report that FKBP12 binds the IP3R at residues 1400-1401, a leucyl-prolyl dipeptide epitope that structurally resembles FK506. We further demonstrate that binding to IP3R at this site enables FKBP12 to interact with calcineurin, presumably to anchor the phosphatase to IP3R and modulate the receptor's phosphorylation status. We propose that FK506 promotes an FKBP12-calcineurin interaction by mimicking structurally similar dipeptide epitopes present within proteins that use FKBP12 to anchor calcineurin to the appropriate physiologic substrates.
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Affiliation(s)
- A M Cameron
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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109
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Neuroprotective actions of FK506 in experimental stroke: in vivo evidence against an antiexcitotoxic mechanism. J Neurosci 1997. [PMID: 9278529 DOI: 10.1523/jneurosci.17-18-06939.1997] [Citation(s) in RCA: 165] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The cellular mechanisms underlying the neuroprotective action of the immunosuppressant FK506 in experimental stroke remain uncertain, although in vitro studies have implicated an antiexcitotoxic action involving nitric oxide and calcineurin. The present in vivo study demonstrates that intraperitoneal pretreatment with 1 and 10 mg/kg FK506, doses that reduced the volume of ischemic cortical damage by 56-58%, did not decrease excitotoxic damage induced by quinolinate, NMDA, and AMPA. Similarly, intravenous FK506 did not reduce the volume of striatal quinolinate lesions at a dose (1 mg/kg) that decreased ischemic cortical damage by 63%. The temporal window for FK506 neuroprotection was defined in studies demonstrating efficacy using intravenous administration at 120 min, but not 180 min, after middle cerebral artery occlusion. The noncompetitive NMDA receptor antagonist MK801 reduced both ischemic and excitotoxic damage. Histopathological data concerning striatal quinolinate lesions were replicated in neurochemical experiments. MK801, but not FK506, attenuated the loss of glutamate decarboxylase and choline acetyltransferase activity induced by intrastriatal injection of quinolinate. The contrasting efficacy of FK506 in ischemic and excitotoxic lesion models cannot be explained by drug pharmacokinetics, because brain FK506 content rose rapidly using both treatment protocols and was sustained at a neuroprotective level for 3 d. Although these data indicate that an antiexcitotoxic mechanism is unlikely to mediate the neuroprotective action of FK506 in focal cerebral ischemia, the finding that intravenous cyclosporin A (20 mg/kg) reduced ischemic cortical damage is consistent with the proposed role of calcineurin.
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110
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Abstract
The immunophilins are a family of proteins that are receptors for immunosuppressant drugs, such as cyclosporin A, FK506, and rapamycin. They occur in two classes, the FK506-binding proteins (FKBPs), which bind FK506 and rapamycin, and the cyclophilins, which bind cyclosporin A. Immunosuppressant actions of cyclosporin A and FK506 derive from the drug-immunophilin complex binding to and inhibiting the phosphatase calcineurin. Rapamycin binds to FKBP and the complex binds to Rapamycin And FKBP-12 Target (RAFT). RAFT affects protein translation by phosphorylating p70-S6 kinase, which phosphorylates the ribosomal S6 protein, and 4E-BP1, a repressor of protein translation initiation. Immunophilin levels are much higher in the brain than in immune tissues, and levels of FKBP12 increase in regenerating neurons in parallel with GAP-43. Immunophilin ligands, including nonimmunosuppressants that do not inhibit calcineurin, stimulate regrowth of damaged peripheral and central neurons, including dopamine, serotonin, and cholinergic neurons in intact animals. FKPB12 is physiologically associated with the ryanodine and inositol 1,4,5-trisphosphate (IP3) receptors and regulates their calcium flux. By influencing phosphorylation of neuronal nitric oxide synthase, FKBP12 regulates nitric oxide formation, which is reduced by FK506.
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Affiliation(s)
- D M Sabatini
- Johns Hopkins University School of Medicine, Department of Neuroscience, Baltimore, MD 21205, USA
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111
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Gold BG, Zeleny-Pooley M, Wang MS, Chaturvedi P, Armistead DM. A nonimmunosuppressant FKBP-12 ligand increases nerve regeneration. Exp Neurol 1997; 147:269-78. [PMID: 9344552 DOI: 10.1006/exnr.1997.6630] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The immunosuppressant drugs FK506 and cyclosporin A inhibit T-cell proliferation via a common mechanism: calcineurin inhibition following binding to their respective binding proteins, the peptidyl prolyl isomerases FKBP-12 and cyclophilin A. In contrast, FK506, but not cyclosporin A, accelerates nerve regeneration. In the present study, we show that the potent FKBP-12 inhibitor V-10,367, which lacks the structural components of FK506 required for calcineurin inhibition, increases neurite outgrowth in SH-SY5Y neuroblastoma cells and speeds nerve regeneration in the rat sciatic nerve crush model. In SH-SY5Y cells, V-10,367 increased the lengths of neurite processes in a concentration-dependent (between 1 and 10 nM) fashion over time (up to 168 h). Daily subcutaneous injections of V-10,367 accelerated the onset of clinical signs of functional recovery in the hind feet compared to vehicle-treated control animals. Interdigit distances (between the first and fifth digits) measured on foot prints obtained during walking showed an increase in toe spread in V-10,367-treated rats compared to vehicle-treated controls. Electron microscopy demonstrated larger regenerating axons distal to the crush site in the sciatic nerve from V-10,367-treated rats. Quantitation of axonal areas in the soleus nerve revealed a shift to larger axonal calibers in V-10,367-treated rats (400 or 200 mg/kg/day); mean axonal areas were increased by 52 and 59%, respectively, compared to vehicle-treated controls. FKBP-12 ligands lacking calcineurin inhibitory activity represent a new class of potential drugs for the treatment of human peripheral nerve disorders.
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Affiliation(s)
- B G Gold
- Center for Research on Occupational and Environmental Toxicology and Department of Cell and Developmental Biology, Oregon Health Sciences University, Portland 97201-3098, USA
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112
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Alevizopoulos A, Dusserre Y, Rüegg U, Mermod N. Regulation of the transforming growth factor beta-responsive transcription factor CTF-1 by calcineurin and calcium/calmodulin-dependent protein kinase IV. J Biol Chem 1997; 272:23597-605. [PMID: 9295299 DOI: 10.1074/jbc.272.38.23597] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Transforming growth factor beta (TGF-beta) is a pluripotent peptide hormone that regulates various cellular activities, including growth, differentiation, and extracellular matrix protein gene expression. We previously showed that TGF-beta induces the transcriptional activation domain (TAD) of CTF-1, the prototypic member of the CTF/NF-I family of transcription factors. This induction correlates with the proposed role of CTF/NF-I binding sites in collagen gene induction by TGF-beta. However, the mechanisms of TGF-beta signal transduction remain poorly understood. Here, we analyzed the role of free calcium signaling in the induction of CTF-1 transcriptional activity by TGF-beta. We found that TGF-beta stimulates calcium influx and mediates an increase of the cytoplasmic calcium concentration in NIH3T3 cells. TGF-beta induction of CTF-1 is inhibited in cells pretreated with thapsigargin, which depletes the endoplasmic reticulum calcium stores, thus further arguing for the potential relevance of calcium mobilization in TGF-beta action. Consistent with this possibility, expression of a constitutively active form of the calcium/calmodulin-dependent phosphatase calcineurin or of the calcium/calmodulin-dependent kinase IV (DeltaCaMKIV) specifically induces the CTF-1 TAD and the endogenous mouse CTF/NF-I proteins. Both calcineurin- and DeltaCaMKIV-mediated induction require the previously identified TGF-beta-responsive domain of CTF-1. The immunosuppressants cyclosporin A and FK506 abolish calcineurin-mediated induction of CTF-1 activity. However, TGF-beta still induces the CTF-1 TAD in cells treated with these compounds or in cells overexpressing both calcineurin and DeltaCaMKIV, suggesting that other calcium-sensitive enzymes might mediate TGF-beta action. These results identify CTF/NF-I as a novel calcium signaling pathway-responsive transcription factor and further suggest multiple molecular mechanisms for the induction of CTF/NF-I transcriptional activity by growth factors.
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Affiliation(s)
- A Alevizopoulos
- Laboratory of Molecular Biotechnology, Center of Biotechnology UNIL-EPFL, DC-IGC, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
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113
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Kageyama M, Fujita H, Goto W, Nakata K, Shirasawa E, Kanai A. FK506-binding proteins regulate smooth muscle contractility by altering neurotransmitter release. Eur J Pharmacol 1997; 333:223-9. [PMID: 9314039 DOI: 10.1016/s0014-2999(97)01146-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
To determine the roles of FK506-binding proteins, receptors for the immunosuppressant FK506, in tachykinin release, we examined the effects of the FK506 derivative ascomycin, [3S-[3R[E(1S,3S,4S)],4S,5R,8S,9E,12R,14R,15S,16R,18S,1 9S,26aR]]-8-ethyl- 5,6,8,11,12,13,14,15,16,17,18,19,24,25,26,26a-hexadecahydro- 5,19-dihydroxy- 3-[2-(4-hydroxy-3-methoxycyclohexyl)-1-methylethenyl]-14,16- dimethoxy- 4,10,12,18-tetramethyl-15,19-epoxy-3H-pyrido[2,1-c][1,4]oxaazacyclotr icosine -1,7,20,21(4H,23H)-tetrone, on the contractility of the rabbit iris sphincter muscle. Ascomycin (10(-7) to 10(-5) M) caused concentration-dependent contractions, which were greatly attenuated by preexposure to rapamycin (10(-5) M), a FK506 receptor antagonist. Similarly, this contractile effect was abolished by preexposure to FK888 (10(-6) M), a tachykinin receptor antagonist, and to capsaicin (10(-5) M), a tachykinin-depleting agent. L-type voltage-dependent Ca2+ channel blockers, nicardipine (10(-5) M) and verapamil (5 x 10(-5) M), inhibited the ascomycin-induced contraction, but the N-type channel blocker omega-conotoxin (10(-6) M) did not. These results suggest that ascomycin stimulates tachykinin release by its binding to FK506-binding proteins and the subsequent activation of L-type Ca2+ channels. Thus, FK506-binding proteins may regulate muscle contractility by altering transmitter release from peripheral tachykininergic nerves.
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Affiliation(s)
- M Kageyama
- Ophthalmic Research Division, Santen Pharmaceutical Co. Ltd., Nara, Japan
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114
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Abstract
It is now clear that cytokines traditionally viewed as immune modulators participate in inflammatory responses within the adult nervous system. However, in the developing nervous system hematolymphopoietic cytokines also play a role unrelated to neural-immune interactions. Instead, many of these factors subserve primary regulatory functions related both to the morphogenesis and to the cellular maturation of the central and peripheral nervous systems. This article focuses specifically on cytokine actions in neural development.
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Affiliation(s)
- M F Mehler
- Dept of Neurology, Rose F. Kennedy Center for Research in Mental Retardation and Human Development, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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115
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Durham HD, Alonso-Vanegas MA, Sadikot AF, Zhu L, Lochmüller H, Massie B, Nalbantoglu J, Karpati G. The immunosuppressant FK506 prolongs transgene expression in brain following adenovirus-mediated gene transfer. Neuroreport 1997; 8:2111-5. [PMID: 9243594 DOI: 10.1097/00001756-199707070-00005] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
First generation, replication-defective adenoviral vectors are highly effective for gene transfer into the central nervous system, but the host's immune response limits the utility of this vector for possible therapy of neurological disease or long-term gene transfer studies in experimental animals. We have demonstrated the effectiveness of FK506 (tacrolimus), a powerful immunosuppressant that readily crosses the blood-brain barrier, in maintaining adenovirus-mediated reporter gene transfer following stereotaxic injection of the recombinant (AdCMVlacZ) into mouse striatum. After 28 days, beta-galactosidase expression was reduced by 75% relative to day 10 in immunocompetent animals, accompanied by an inflammatory reaction in the region of transduced cells; however, in mice receiving daily s.c. injections of FK506, beta-galactosidase activity was maintained at the 10 days post-injection level.
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Affiliation(s)
- H D Durham
- Montreal Neurological Institute, McGill University, Quebec, Canada
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116
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Wang JH, Ko GY, Kelly PT. Cellular and molecular bases of memory: synaptic and neuronal plasticity. J Clin Neurophysiol 1997; 14:264-93. [PMID: 9337139 DOI: 10.1097/00004691-199707000-00002] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Discoveries made during the past decade have greatly improved our understanding of how the nervous system functions. This review article examines the relation between memory and the cellular mechanisms of neuronal and synaptic plasticity in the central nervous system. Evidence indicating that activity-dependent short- and long-term changes in strength of synaptic transmission are important for memory processes is examined. Focus is placed on one model of synaptic plasticity called long-term potentiation, and its similarities with memory processes are illustrated. Recent studies show that the regulation of synaptic strength is bidirectional (e.g., synaptic potentiation or depression). Mechanisms involving intracellular signaling pathways that regulate synaptic strength are described, and the specific roles of calcium, protein kinases, protein phosphatases, and retrograde messengers are emphasized. Evidence suggests that changes in synaptic ultrastructure, dendritic ultrastructure, and neuronal gene expression may also contribute to mechanisms of synaptic plasticity. Also discussed are recent findings about postsynaptic mechanisms that regulate short-term synaptic facilitation and neuronal burst-pattern activity, as well as evidence about the subcellular location (presynaptic or postsynaptic) of mechanisms involved in long-term synaptic plasticity.
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Affiliation(s)
- J H Wang
- Department of Neurobiology and Anatomy, University of Texas Medical School-Houston, 77225, U.S.A
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117
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Postsynaptic calcineurin activity downregulates synaptic transmission by weakening intracellular Ca2+ signaling mechanisms in hippocampal CA1 neurons. J Neurosci 1997. [PMID: 9169521 DOI: 10.1523/jneurosci.17-12-04600.1997] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Protein phosphorylation and dephosphorylation are believed to functionally couple neuronal activity and synaptic plasticity. Our previous results indicated that postsynaptic Ca2+/calmodulin (CaM) signaling pathways play an important role in setting synaptic strength, and calcineurin (CaN) activity limits synaptic responses during basal synaptic transmission and long-term potentiation expression. The inhibition of postsynaptic CaN activity by FK-506 or an autoinhibitory peptide induced synaptic potentiation in hippocampal slices, which occludes tetanus-induced LTP. FK-506-induced synaptic potentiation was expressed in adult but not young rats. To elucidate mechanisms underlying CaN-inhibited synaptic potentiation, we co-injected certain agents affecting Ca2+ signaling pathways with CaN inhibitors into CA1 neurons. Synaptic potentiation induced by FK-506 was significantly attenuated by co-injecting BAPTA, heparin/dantrolene (inhibitors of intracellular Ca2+ release), a CaM-binding peptide, or CaM-KII/PKC pseudosubstrate peptides. These results indicate that postsynaptic CaN activity can downregulate evoked synaptic transmission by weakening intracellular Ca2+ signals and downstream protein kinase activities.
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118
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Raufman JP, Malhotra R, Raffaniello RD. Regulation of calcium-induced exocytosis from gastric chief cells by protein phosphatase-2B (calcineurin). BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1357:73-80. [PMID: 9202177 DOI: 10.1016/s0167-4889(97)00023-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The molecular mechanisms whereby calcium stimulates secretion are uncertain. In the present study, we used streptolysin O (SLO)-permeabilized chief cells from guinea pig stomach to investigate whether protein phosphatase-2B (calcineurin), a calcium/calmodulin-dependent, serine/threonine phosphatase plays a role in mediating calcium-induced pepsinogen secretion. Preincubation of cells with alpha-naphthylphosphate, a non-specific phosphatase inhibitor, decreased calcium-induced secretion. Likewise, specific inhibitors of protein phosphatase-2B (cyclosporin-A and FK-506) caused a dose-dependent reduction in calcium-induced pepsinogen secretion. Moreover, in intact cells, cyclosporin-A and FK-506 inhibited pepsinogen secretion caused by cholecystokinin, carbamylcholine and A23187, agonists known to increase chief cell cytosolic calcium. Okadaic acid, an inhibitor of protein phosphatase-1 and -2A, had no effect on secretion caused by these agonists. Chief cell calcium-dependent phosphatase activity, measured using radiolabeled casein as substrate, was reduced selectively by inhibitors of protein phosphatase-2B. Endogenous substrates for calcium/calmodulin-dependent phosphatase activity were identified by analyzing chief cell lysates using 2-dimensional gel electrophoresis. Increasing the cytosolic calcium concentration resulted in dephosphorylation of a 55-kDa, acidic cytoskeletal protein. FK-506 inhibited dephosphorylation of this protein. Thus, in permeabilized chief cells, specific inhibitors of protein phosphatase-2B inhibit calcium-induced pepsinogen secretion, calcium/calmodulin-dependent phosphatase activity and calcium-induced dephosphorylation of a 55-kDa, acidic cytoskeletal protein. These results support the hypothesis that protein phosphatase-2B (calcineurin) plays an important role in mediating calcium-induced exocytosis.
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Affiliation(s)
- J P Raufman
- Division of Gastroenterology, University of Arkansas for Medical Sciences, Little Rock 72205-7199, USA
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119
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Xiao RP, Valdivia HH, Bogdanov K, Valdivia C, Lakatta EG, Cheng H. The immunophilin FK506-binding protein modulates Ca2+ release channel closure in rat heart. J Physiol 1997; 500 ( Pt 2):343-54. [PMID: 9147322 PMCID: PMC1159388 DOI: 10.1113/jphysiol.1997.sp022025] [Citation(s) in RCA: 142] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
1. The nature of the signal that terminates the release of Ca2+ from the cardiac sarcoplasmic reticulum has remained elusive. This study was intended to examine whether FK506-binding protein (FKBP), which is tightly associated to the ryanodine receptor (RyR)/Ca2+ release channel, plays a role in the termination of Ca(2+)-induced Ca2+ release (CICR) in heart. 2. Confocal microscopy and the Ca2+ indicator fluo-3 were used to visualize the elementary release events, i.e. 'Ca2+ sparks' in rat ventricular myocytes under resting or voltage-clamped conditions. Additionally, electrophysiological single-channel recordings, at constant [Ca2+] or during [Ca2+] steps produced by photorelease of caged Ca2+, were obtained from rat cardiac RyRs incorporated in planar lipid bilayers. 3. Inhibition of FKBP by the immunosuppressants FK506 or rapamycin increased the duration of spontaneous or depolarization-evoked Ca2+ sparks 6- to 7-fold. In addition, Ca2+ sparks were seen with two-level amplitudes, corresponding to full and half normal spark amplitude. 4. FK506 potentiated and prolonged electrically stimulated [Ca2+]i transients and contractions, but did not affect the amplitude and kinetics of the L-type Ca2+ channel current. 5. In planar lipid bilayers, FK506 (15 microM) prolonged approximately 7-fold the mean open lifetime of reconstituted single RyRs, induced the appearance of long-lasting subconductance states, and markedly slowed the spontaneous decay of RyR activity elicited by fast and sustained Ca2+ stimuli. The time constant of the spontaneous decay of activity increased from 1.8 s in control to > or = 20 s in the presence of FK506. 6. We conclude that FKBP may afford an intrinsic mechanism to terminate RyR openings and it may thus exert a negative feedback on CICR in heart cells.
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Affiliation(s)
- R P Xiao
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
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120
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Steiner JP, Connolly MA, Valentine HL, Hamilton GS, Dawson TM, Hester L, Snyder SH. Neurotrophic actions of nonimmunosuppressive analogues of immunosuppressive drugs FK506, rapamycin and cyclosporin A. Nat Med 1997; 3:421-8. [PMID: 9095176 DOI: 10.1038/nm0497-421] [Citation(s) in RCA: 262] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We show that the nonimmunosuppressive analogues of the immunosuppressive drugs FK506, rapamycin and cyclosporin A promote neurite outgrowth both in PC12 cells and sensory neuronal cultures of dorsal root ganglia with potencies resembling their immunosuppressive homologues. Neurotrophic potencies of the immunophilin ligands resemble their potencies in binding to and inhibiting the rotamase activity of FKBP-12 of cyclophilin. Since nonimmunosuppressive immunophilin ligands, which are devoid of calcineurin inhibitory activity, are equally neurotrophic, inhibition of calcineurin activity is not the mediator of the neurotrophic effects. The immunophilin ligands are neurotrophic in intact animals. FK506 and L-685,818 (the C18-hydroxy, C21-ethyl derivative of FK506) treatment of rats with crushed sciatic nerves enhances both functional and morphologic recovery. The striking potency of these agents, their bioavailability and the dissociation of neurotrophic from immunosuppressant actions argue for their therapeutic relevance in the treatment of neurodegenerative diseases.
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Affiliation(s)
- J P Steiner
- Department of Neurobiological Research, Guilford Pharmaceuticals Inc., Baltimore, Maryland 21224, USA
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121
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Buchkremer-Ratzmann I, Witte OW. Pharmacological reduction of electrophysiological diaschisis after photothrombotic ischemia in rat neocortex. Eur J Pharmacol 1997; 320:103-9. [PMID: 9059842 DOI: 10.1016/s0014-2999(96)00891-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Focal cerebral lesions in the rat brain induced by photothrombosis cause hyperexcitability of the surrounding brain. This can be demonstrated in brain slices taken from animals several days after lesioning, by analysis of field potential responses to paired-pulse stimulation. We now investigated whether and how these remote effects of a cortical lesion can be modified pharmacologically. Application of the NMDA receptor antagonist, MK-801 ((+)-5-methyl-10, 11-dihydro-5H-dibnzo[a,d]cyclohepten-5,10-imine), was shown to block induction of immediate early genes and activation of astrocytes as evidenced by glial fibrillary acidic protein (GFAP) staining in the photothrombosis model. However, MK-801 did not affect the hyperexcitability that had been demonstrated by field potential recordings in brain slices. In another series of experiments, lubeluzole ((+)-(S)-4-(2-benzothiazolylmethylamino)-alpha-[(3,4-difluoroph enoxy) methyl]-1-piperidineethanol), which inhibits the glutamate-activated nitric oxide pathway as evidenced by down-regulation of intracellular cyclic GMP, was given immediately after induction of the insult. This reduced hyperexcitability as investigated 7 days later. In the light of these data one can suggest that a nitric oxide-cyclic GMP-related mechanism may be responsible for functional alterations in the surround of photothrombotic brain lesions.
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122
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Pahl A, Gewies A, Keller U. ScCypB is a novel second cytosolic cyclophilin from Streptomyces chrysomallus which is phylogenetically distant from ScCypA. MICROBIOLOGY (READING, ENGLAND) 1997; 143 ( Pt 1):117-126. [PMID: 9025285 DOI: 10.1099/00221287-143-1-117] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A novel second streptomycete cyclophilin gene-designated sccypB-was isolated from a cosmid gene library of Streptomyces chrysomallus by using as gene probe a fragment of the previously isolated cyclophilin gene sccypA of the same organism. From its sequence the gene sccypB should encode a protein of M(r) 18868. Expression of sccypB in Escherichia coli as a hexaHis-tagged fusion protein (H6ScCypB) and enzymic characterization of the purified protein showed that, like ScCypA, ScCypB is a peptidyl-prolyl cis-trans isomerase (PPIase). The specific activity and substrate specificity of the enzyme were comparable to that of ScCypA, but it was threefold less sensitive to inhibition by cyclosporin A (CsA). In contrast to ScCypA, which is abundant and exists in free and liganded form, ScCypB was 50- to 100-fold less abundant in cytosol-derived protein fractions of S. chrysomallus or Streptomyces lividans, as revealed by Western blot analyses, suggesting a specialized function for this enzyme in the streptomycete cell. Both sccypB and sccypA were found to be present as single copies in the genome of S. chrysomallus and hybridized to a single band in chromosomal DNAs of other streptomycetes. High-level expression of sccypB as well as of sccypA cloned into the expression vector pIJ702 did not produce detectable changes in growth and morphology of S. chrysomallus and S. lividans. Calculations of similarities to known cyclophilin sequences and construction of phylogenetic trees indicated that ScCypB and ScCypA are phylogenetically distant from each other. While ScCypA is clearly related to the eukaryotic cyclophilins, the analyses show the sequence of ScCypB to be the most divergent of all cyclophilin sequences, indicating that it possibly constitutes a cluster by itself.
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Affiliation(s)
- Andreas Pahl
- Institut fr Biochemie und Molekulare Biologie, Technische Universitt Berlin, Franklinstrasse 29, D-10587 Berlin-Charlottenburg, Germany
| | - Andreas Gewies
- Institut fr Biochemie und Molekulare Biologie, Technische Universitt Berlin, Franklinstrasse 29, D-10587 Berlin-Charlottenburg, Germany
| | - Ullrich Keller
- Institut fr Biochemie und Molekulare Biologie, Technische Universitt Berlin, Franklinstrasse 29, D-10587 Berlin-Charlottenburg, Germany
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Chambraud B, Radanyi C, Camonis JH, Shazand K, Rajkowski K, Baulieu EE. FAP48, a new protein that forms specific complexes with both immunophilins FKBP59 and FKBP12. Prevention by the immunosuppressant drugs FK506 and rapamycin. J Biol Chem 1996; 271:32923-9. [PMID: 8955134 DOI: 10.1074/jbc.271.51.32923] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
We have identified a human gene encoding a 48-kDa protein that specifically interacts with the peptidyl prolyl isomerase FK506-binding protein 59 (FKBP59) and also with the well known FKBP12. FKBP59 and FKBP12 belong to the large family of immunophilins that bind the macrolide immunosuppressant drugs FK506 and rapamycin. The yeast two-hybrid system was used to isolate target proteins that interact with the immunosuppressant drug binding domain of the rabbit FKBP59. The cDNA for an as yet unidentified protein was isolated and cloned from a Jurkat cell library. The cDNA sequence of 1804 base pairs reveals an open reading frame of 417 amino acids. In vitro experiments suggest a direct interaction between FKBP59 and this new target protein. This specific association seems to be restricted to the FKBP family, since it also occurs both in vivo and in vitro with FKBP12 but not with cyclophilin 40. This novel protein was named FKBP-associated protein (FAP48). The formation of the complexes between FKBP59 or FKBP12 and FAP48 is prevented by FK506 and rapamycin in a dose-dependent manner. These results suggest that FAP48 shares or overlaps the macrolide binding site on FKBP59 as well as on FKBP12 and therefore may represent a natural common ligand of these immunosuppressant drug receptors.
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Affiliation(s)
- B Chambraud
- INSERM (U33) and Collège de France, 80 rue du Général Leclerc, 94276 Bicêtre Cédex, France
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124
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Sharkey J, Crawford JH, Butcher SP, Marston HM. Tacrolimus (FK506) ameliorates skilled motor deficits produced by middle cerebral artery occlusion in rats. Stroke 1996; 27:2282-6. [PMID: 8969794 DOI: 10.1161/01.str.27.12.2282] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND AND PURPOSE Tacrolimus (FK506) is a potent immunosuppressant that is presently in clinical use for prevention of allograft rejection. Recently, animal studies reporting significant reductions in the volume of tissue damage associated with cardiac, hepatic, and cerebral ischemia suggest that tacrolimus may also be of use in the clinical management of stroke. In the present study, we examine whether the neuroprotective effects of tacrolimus, as assessed by histological outcome, are accompanied by an amelioration of the skilled motor deficits induced in the rat by middle cerebral artery occlusion (MCAO). METHODS Animals were trained to perform a skilled paw-reaching task before MCAO by perivascular microinjections of endothelin-1. Tacrolimus (1 mg/kg, n = 6) or vehicle (n = 6) was administered by intravenous infusion 1 minute after MCAO. After a 5-day postoperative recovery period, the rats were retested for skilled paw-reaching ability for an additional 9 days. RESULTS In vehicle-treated rats, MCAO resulted in a profound bilateral impairment in skilled paw use. Rats treated with tacrolimus, although still impaired, performed significantly better than those treated with vehicle alone (P < .01). Histological analysis, 14 days after occlusion, confirmed the neuroprotective efficacy of tacrolimus with a 66% reduction in the volume of hemispheric brain damage produced by MCAO (P < .01). CONCLUSIONS The present studies show that tacrolimus not only protects neural tissue from focal cerebral ischemia but also significantly ameliorates the deficits in skilled motor ability produced by this lesion. These data provide further support for the view that tacrolimus may be of use in the treatment of stroke.
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Affiliation(s)
- J Sharkey
- Fujisawa Institute of Neuroscience, University of Edinburgh, UK.
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125
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Ankarcrona M, Dypbukt JM, Orrenius S, Nicotera P. Calcineurin and mitochondrial function in glutamate-induced neuronal cell death. FEBS Lett 1996; 394:321-4. [PMID: 8830666 DOI: 10.1016/0014-5793(96)00959-3] [Citation(s) in RCA: 194] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We have previously reported that glutamate can trigger a succession of necrosis and apoptosis in cerebellar granule cells (CGC). Since specific blockers of the N-methyl-D-aspartate (NMDA) receptor channel prevented both types of cell death, the role of Ca2+-dependent processes in the initiation of glutamate toxicity was further investigated. We examined the possible involvement of mitochondria and the role of the Ca2+/calmodulin-regulated protein phosphatase, calcineurin, in the development of either type of cell death. Cyclosporin A and the more selective calcineurin inhibitor, FK-506, prevented the development of both early necrosis and delayed apoptosis. In addition, cyclosporin A prevented the collapse of mitochondrial membrane potential observed during the exposure to glutamate and the concomitant necrotic phase. When CsA was added immediately after glutamate removal, it also prevented delayed apoptosis of neurons that had survived the necrotic phase. Altogether, these results suggest the involvement of calcineurin and a role for mitochondrial deenergization as early signals in neuronal apoptosis induced by glutamate.
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Affiliation(s)
- M Ankarcrona
- Institute of Environmental Medicine, Division of Toxicology, Karolinska Institute, Stockholm, Sweden
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126
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127
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Raufman JP, Lin J, Raffaniello RD. Calcineurin mediates calcium-induced potentiation of adenylyl cyclase activity in dispersed chief cells from guinea pig stomach. Further evidence for cross-talk between signal transduction pathways that regulate pepsinogen secretion. J Biol Chem 1996; 271:19877-82. [PMID: 8702699 DOI: 10.1074/jbc.271.33.19877] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
In cholera toxin-treated gastric chief cells, incubation with a cholinergic agonist (carbamylcholine), a regulatory peptide (cholecystokinin), or a calcium ionophore (A23187) causes a dose- and time-dependent potentiation of cAMP levels. Because this augmented response is calcium/calmodulin-dependent, we hypothesized that it was mediated by calcineurin (protein phosphatase 2B). To test this hypothesis, we examined the actions of calcineurin inhibitors on secretagogue-induced potentiation of cAMP levels in guinea pig chief cells. Preincubation of cells with 0.1 microM FK-506 completely prevented carbachol-induced augmentation of cAMP levels and pepsinogen secretion from cholera toxin-treated cells. Cyclosporin-A, another calcineurin inhibitor, also prevented the augmented cAMP response. FK-506 and cyclosporin inhibited augmentation of cAMP levels following treatment with cholecystokinin(26-33) and A23187, but not the smaller increase in cAMP following treatment with a phorbol ester that activates protein kinase C. Hence, the actions of calcineurin inhibitors were limited to secretagogues that increase cellular calcium. Rapamycin, an agent that competes with FK-506 for the immunophilin, FK binding protein 12, does not inhibit calcineurin. In the present study, preincubation with rapamycin did not prevent carbachol-induced augmentation of cAMP levels in cholera toxin-treated chief cells. However, a molar excess of rapamycin reversed the inhibitory actions of FK-506. These experiments provide further evidence that the actions of FK-506 on cholera toxin-treated gastric chief cells are caused by its inhibitory actions on calcineurin. FK-506 also inhibited potentiation of cAMP levels when carbachol was added to cells that were preincubated with forskolin, an agent that directly activates adenylyl cyclase. We conclude that, in gastric chief cells, calcineurin mediates cross-talk between the calcium/calmodulin and adenylyl cyclase signaling pathways.
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Affiliation(s)
- J P Raufman
- Division of Gastroenterology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199, USA
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128
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Moriwaki A, Lu YF, Hayashi Y, Tomizawa K, Tokuda M, Itano T, Hatase O, Matsui H. Immunosuppressant FK506 prevents mossy fiber sprouting induced by kindling stimulation. Neurosci Res 1996; 25:191-4. [PMID: 8829156 DOI: 10.1016/0168-0102(96)01036-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Kindling stimulation induces expansive growth of the axons of the dentate granule cells, the mossy fiber, into several areas of the hippocampus. An intraperitoneal injection of the immunosuppressant drug FK506, which is a specific inhibitor of Ca(2+)-calmodulin dependent phosphatase, calcineurin, prevented the full development of kindling as well as mossy fiber sprouting. The results show a correlation between mossy fiber sprouting and the development of kindling. The results suggest also that calcineurin may have a promoting role in mossy fiber sprouting and subsequent synaptogenesis.
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Affiliation(s)
- A Moriwaki
- First Department of Physiology, Okayama University Medical School, Japan
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129
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Muraoka K, Fujimoto K, Sun X, Yoshioka K, Shimizu K, Yagi M, Bose H, Miyazaki I, Yamamoto K. Immunosuppressant FK506 induces interleukin-6 production through the activation of transcription factor nuclear factor (NF)-kappa(B). Implications for FK506 nephropathy. J Clin Invest 1996; 97:2433-9. [PMID: 8647935 PMCID: PMC507328 DOI: 10.1172/jci118690] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
FK506 is a powerful immunosuppressive drug currently in use that inhibits the activation of several transcription factors (nuclear factor (NF)-AT and NF-kappaB) critical for T cell activation. We show here that, contrary to the situation in T cells, FK506 activates transcription factor NF-kappaB in nonlymphoid cells such as fibroblasts and renal mesangial cells. We further show that FK506 induces NF-kappaB-regulated IL-6 production in vitro and in vivo, in particular in kidney. IL-6 has been shown previously to produce renal abnormalities in vivo, such as mesangioproliferative glomerulonephritis. Similar renal abnormalities were also observed in FK506-treated animals. These results thus suggest a causal relationship between FK506-induced NF-kappaB activation/IL-6 production and some of FK506-induced renal abnormalities.
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Affiliation(s)
- K Muraoka
- Department of Molecular Pathology, Cancer Research Institute, School of Medicine, Kanazawa University, 13-1 Takaramachi, Kanazawa, Ishikawa 920, Japan
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131
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Artalejo CR, Elhamdani A, Palfrey HC. Calmodulin is the divalent cation receptor for rapid endocytosis, but not exocytosis, in adrenal chromaffin cells. Neuron 1996; 16:195-205. [PMID: 8562084 DOI: 10.1016/s0896-6273(00)80036-7] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Exocytosis and the ensuing rapid endocytosis in adrenal chromaffin cells are both Ca(2+)-dependent phenomena but differ in their divalent cation specificity, implying distinct Ca2+ receptors for the two processes. To ascertain whether calmodulin is the Ca2+ receptor for either process, we blocked its function by introducing calmodulin-binding peptides or anti-calmodulin antibodies into these cells. Exo/endocytosis was followed by measurement of cell membrane capacitance. Rapid endocytosis, but not exocytosis, was abolished by these treatments, indicating that calmodulin is the Ca2+ receptor for rapid endocytosis but is not involved in exocytosis. The principal calmodulin target is not protein phosphatase-2B, as antagonism of this enzyme did not inhibit but accelerated rapid endocytosis. Calmodulin may thus regulate both the rate and extent of rapid endocytosis by distinct pathways.
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Affiliation(s)
- C R Artalejo
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois 60208, USA
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132
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Sadoshima J, Izumo S. Rapamycin selectively inhibits angiotensin II-induced increase in protein synthesis in cardiac myocytes in vitro. Potential role of 70-kD S6 kinase in angiotensin II-induced cardiac hypertrophy. Circ Res 1995; 77:1040-52. [PMID: 7586215 DOI: 10.1161/01.res.77.6.1040] [Citation(s) in RCA: 140] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
It has been suggested that phosphorylation of a 40S ribosomal protein, S6, regulates protein synthesis. Two distinct families of S6 kinase have been identified, the rsk-encoded 85- to 92-kD S6 kinase (RSK) and the 70- or 85-kD S6 kinase (p70S6K). We have previously shown that hypertrophic stimuli, such as angiotensin II (Ang II), rapidly activate RSK in cardiac myocytes. However, RSK and p70S6K are regulated by distinct mechanisms, and p70S6K, but not RSK, is the physiological S6 kinase in vivo in other cell types. Using cultured neonatal rat ventricular myocytes, we examined whether Ang II activates p70S6K and investigated the effect of rapamycin, a potent yet indirect inhibitor of p70S6K, on the Ang II-induced hypertrophic response. Immunoblot analyses indicate that cardiac myocytes express the 70- and 85-kD forms of p70s6K. Ang II caused a rapid and sustained activation of p70S6K through the type I Ang II receptor. Rapamycin inhibited Ang II-induced activation of p70S6K in a dose-dependent manner, with an IC50 of 0.14 ng/mL (0.15 nmol/L). Rapamycin did not inhibit Ang II-induced activation of tyrosine kinase, mitogen-activated protein kinase, RSK, and protein kinase C. The effect of rapamycin is unlikely to be mediated by its effect on p34cdc2 and p33cdk2 because Ang II did not activate these cell cycle-dependent kinases in cardiac myocytes. In contrast, a dose-dependent inhibition of p70S6K by rapamycin is very closely correlated with its inhibition of the Ang II-induced increase in protein synthesis. Interestingly, rapamycin did not affect the Ang II-induced activation of specific gene expression, including the immediate-early gene c-fos and fetal type genes, such as atrial natriuretic factor and skeletal alpha-actin. Moreover, rapamycin did not suppress Ang II-induced phenotypic changes at the protein level, such as increased atrial natriuretic factor secretion, expression of beta-myosin heavy chain, and organization of actin into sarcomeric units. These results indicate that p70S6K is activated by Ang II and that a rapamycin-sensitive signaling mechanism, most likely p70S6K, plays an essential role in the Ang II-induced increase in overall protein synthesis but not in Ang II-induced specific phenotypic changes in cardiac myocytes.
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Affiliation(s)
- J Sadoshima
- Division of Cardiology, University of Michigan Medical Center, Ann Arbor 48109-0644, USA
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133
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Ma J, Bhat MB, Zhao J. Rectification of skeletal muscle ryanodine receptor mediated by FK506 binding protein. Biophys J 1995; 69:2398-404. [PMID: 8599646 PMCID: PMC1236477 DOI: 10.1016/s0006-3495(95)80109-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The cytosolic receptor for immunosuppressant drugs, FK506 binding protein (FKBP12), maintains a tight association with ryanodine receptors of sarcoplasmic reticulum (SR) membrane in skeletal muscle. The interaction between FKBP12 and ryanodine receptors resulted in distinct rectification of the Ca release channel. The endogenous FKBP-bound Ca release channel conducted current unidirectionally from SR lumen to myoplasm; in the opposite direction, the channel deactivated with fast kinetics. The binding of FKBP12 is likely to alter subunit interactions within the ryanodine receptor complex, as revealed by changes in conductance states of the channel. Both on- and off-rates of FKBP12 binding to the ryanodine receptor showed clear dependence on the membrane potential, suggesting that the binding sites of FKBP12 reside in or near the conduction pore of the Ca release channel. Rectification of the Ca release channel would prevent counter-current flow during the rapid release of Ca from SR membrane, and thus may serve as a negative feedback mechanism that participates in the process of muscle excitation-contraction coupling.
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Affiliation(s)
- J Ma
- Department of Physiology and Biophysics, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106, USA.
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134
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Antoni FA, Barnard RJ, Shipston MJ, Smith SM, Simpson J, Paterson JM. Calcineurin feedback inhibition of agonist-evoked cAMP formation. J Biol Chem 1995; 270:28055-61. [PMID: 7499291 DOI: 10.1074/jbc.270.47.28055] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The effects of immunosuppressant blockers of calcineurin (protein phosphatase 2B) on cAMP formation and hormone release were investigated in mouse pituitary tumor (AtT20) cells. Immunosuppressants enhanced corticotropin-releasing factor- and isoproterenol-evoked cAMP production in proportion with their potency to block calcineurin. Further analysis of cAMP production revealed that intracellular Ca2+ derived through voltage-regulated calcium channels reduces cAMP formation induced by corticotropin releasing-factor or beta 2-adrenergic stimulation and that this effect of Ca2+ is inhibited by blockers of calcineurin. AtT20 cells were found to express at least three species of adenylyl cyclase mRNA-encoding types 1 and 6 as well as a novel isotype, which appeared to be the predominant species. In two cell lines expressing very low or undetectable levels of the novel cyclase mRNA (NCB20 and HEK293 cells respectively), corticotropin-releasing factor-induced cAMP formation was not altered upon blockage of calcineurin activity. These data identify calcineurin as a Ca2+ sensor that mediates the negative feedback effect of intracellular Ca2+ on receptor-stimulated cAMP production. Furthermore, the effect of calcineurin on cAMP synthesis appears to be associated with the expression of a novel adenylyl cyclase isotype, which is highly abundant in AtT20 cells.
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Affiliation(s)
- F A Antoni
- Department of Pharmacology, University of Edinburgh, Scotland, United Kingdom
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135
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Cameron AM, Steiner JP, Roskams AJ, Ali SM, Ronnett GV, Snyder SH. Calcineurin associated with the inositol 1,4,5-trisphosphate receptor-FKBP12 complex modulates Ca2+ flux. Cell 1995; 83:463-72. [PMID: 8521476 DOI: 10.1016/0092-8674(95)90124-8] [Citation(s) in RCA: 373] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The immunosuppressant drug FK506 binds to the immunophilin protein FKBP12 and inhibits its prolyl isomerase activity. Immunosuppressive actions, however, are mediated via an FK506-FKBP12 inhibition of the Ca(2+)-activated phosphatase calcineurin. Physiologic cellular roles for FKBP12 have remained unclear. FKBP12 is physically associated with the RyR and IP3R Ca2+ channels in the absence of FK506, with added FK506 disrupting these complexes. Dissociation of FKBP12 results in alteration of channel Ca2+ conductance in both cases. We now report that calcineurin is physiologically associated with the IP3R-FKBP12 and RyR-FKBP12 receptor complexes and that this interaction can be disrupted by FK506 or rapamycin. Calcineurin anchored to the IP3R via FKBP12 regulates the phosphorylation status of the receptor, resulting in a dynamic Ca(2+)-sensitive regulation of IP3-mediated Ca2+ flux.
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Affiliation(s)
- A M Cameron
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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136
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Chang HY, Takei K, Sydor AM, Born T, Rusnak F, Jay DG. Asymmetric retraction of growth cone filopodia following focal inactivation of calcineurin. Nature 1995; 376:686-90. [PMID: 7544441 DOI: 10.1038/376686a0] [Citation(s) in RCA: 122] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The neuronal growth cone is thought to be the site of decision making in nerve growth and guidance. One likely mechanism of how the growth cone translates various extracellular cues into directed motility involves rises in intracellular calcium. A variety of physiological cues, such as adhesion molecules and neurotransmitters, increases intracellular calcium, and artificial manipulations of growth cone calcium levels affect growth cone morphology and neurite outgrowth. The molecular events downstream of calcium fluxes are incompletely understood. Here we show that calcineurin, a protein phosphatase enriched in growth cones that is dependent on calcium ions and calmodulin, functions in neurite outgrowth and directed filopodial motility in cultured chick dorsal root ganglia neurons. Cyclosporin A and FK506, inhibitors of calcineurin, delayed neuritogenesis and inhibited neurite extension. Chromophore-assisted laser inactivation of calcineurin in regions of growth cones causes localized filopodial and lamellipodial retraction and influences the direction of subsequent outgrowth. We suggest that a spatial distribution of calcineurin activity within the growth cone can regulate motility and direct outgrowth.
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Affiliation(s)
- H Y Chang
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA
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137
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Nicolaou KC, Piscopio AD, Bertinato P, Chakraborty TK, Minowa N, Koide K. Total Synthesis of Rapamycin. Chemistry 1995. [DOI: 10.1002/chem.19950010509] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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138
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Chakraborty TK, Weber HP, Nicolaou KC. Design and synthesis of a rapamycin-based high affinity binding FKBP12 ligand. CHEMISTRY & BIOLOGY 1995; 2:157-61. [PMID: 9383417 DOI: 10.1016/1074-5521(95)90070-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND The immunosuppressants rapamycin, ascomycin, FK506, and cyclosporin act by binding to a class of cytosolic proteins, the immunophilins. In the case of FK506, ascomycin and cyclosporin, the target of the immunophilin-immunosuppressant complex is calcineurin; in the case of rapamycin, the target is FRAP (TOR/RAFT1). Rapamycin, ascomycin and FK506 have a common domain responsible for binding to FKBP12, their cellular receptor, and different effector domains that determine the target of the complex. Both domains are necessary for signal transduction and biological activity. RESULTS A hybrid molecule containing the rapamycin-FK506-ascomycin binding domain and a peptide tether has been designed, synthesized and biologically evaluated. The designed compound binds to FKBP12 with high affinity but has no biological activity, as expected from its lack of an effector domain. CONCLUSIONS The designed rapamycin-based FKBP12 ligand exhibits powerful binding properties but, unlike rapamycin, shows no activity in IL-6 dependent B-cell proliferation and, in contrast to FK506, shows no activity in the IL-2 reporter assay. The modular nature of this designed molecule should make it possible to generate a series of compounds with effector domains for targeting either calcineurin or FRAP (TOR/RAFT1) or both, as potential biological tools and immunosuppressive agents.
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Affiliation(s)
- T K Chakraborty
- Organic Division III, Indian Institute of Chemical Technology, Hyderabad, India
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