PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of molmedLink to Publisher's site
 
Mol Med. 1996 May; 2(3): 325–333.
PMCID: PMC2230146

Immunophilin regulation of neurotransmitter release.

Abstract

BACKGROUND: The immunophilins are proteins that mediate actions of immunosuppressant drugs such as FK506 and cyclosporin A by binding to calcineurin, inhibiting its phosphatase activity, and increasing the phosphorylation level of transcription factors required for interleukin 2 formation. Though concentrations in the brain greatly exceed levels in immune tissues, no function has been previously established for nervous system immunophilins. Nitric oxide (NO) has been implicated in neurotransmitter release. FK506 appears to inhibit NO production by maintaining NO synthase in a highly phosphorylated and thereby inactivated state. Accordingly, we examined effects of FK506 and cyclosporin A on neurotransmitter release in PC12 cells treated with nerve growth factor (NGF) and in rat brain striatal synaptosomes. MATERIALS AND METHODS: We monitored effects of immunophilin ligands on [3H]-neurotransmitter release from PC12 cells differentiated with NGF. Rat brain striatal synaptosomes were loaded with radiolabeled transmitters and treated with FK506 or cyclosporin A prior to initiating neurotransmitter release with N-methyl-D-aspartate (NMDA) or potassium depolarization. Striatal synaptosomes were also loaded with 32P-orthophosphate and treated with FK506. 32P-labeled synaptic vesicle proteins were isolated from these synaptosomes in an attempt to relate specific FK506-dependent phosphorylation of vesicle proteins with the effects of FK506 on neurotransmitter release. Identification of proteins targetted by FK506 was made by immunoblot analysis and immunoprecipitation. RESULTS: Low nanomolar concentrations of the immunosuppressant drugs FK506 and cyclosporin A (CsA) inhibit transmitter release from PC-12 cells and from NMDA-stimulated brain synaptosomes. By contrast, the immunosuppressants augment depolarization-induced transmitter release from synaptosomes. Synapsin I, a synaptic vesicle phosphoprotein, displays enhanced phosphorylation in the presence of FK506. CONCLUSIONS: Inhibition of transmitter release in PC-12 cells and NMDA-treated synaptosomes by immunosuppressants may reflect augmented phosphorylation of NO synthase, reducing its catalytic activity. This fits with the requirement of NO for transmitter release in PC12 cells and NMDA-treated synaptosomes. Stimulation by immunosuppressants of transmitter release in potassium depolarized synaptosomes may result from augmented phosphorylation of synapsin I, whose phosphorylation is known to facilitate transmitter release. Thus, immunophilins may modulate release of numerous neurotransmitters both by influencing NO formation and the phosphorylation state of synaptic vesicle-associated proteins.

Full text

Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (1.3M), or click on a page image below to browse page by page. Links to PubMed are also available for Selected References.

Images in this article

Click on the image to see a larger version.

Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Schreiber SL. Immunophilin-sensitive protein phosphatase action in cell signaling pathways. Cell. 1992 Aug 7;70(3):365–368. [PubMed]
  • Steiner JP, Dawson TM, Fotuhi M, Glatt CE, Snowman AM, Cohen N, Snyder SH. High brain densities of the immunophilin FKBP colocalized with calcineurin. Nature. 1992 Aug 13;358(6387):584–587. [PubMed]
  • Liu J, Farmer JD, Jr, Lane WS, Friedman J, Weissman I, Schreiber SL. Calcineurin is a common target of cyclophilin-cyclosporin A and FKBP-FK506 complexes. Cell. 1991 Aug 23;66(4):807–815. [PubMed]
  • Dawson TM, Steiner JP, Dawson VL, Dinerman JL, Uhl GR, Snyder SH. Immunosuppressant FK506 enhances phosphorylation of nitric oxide synthase and protects against glutamate neurotoxicity. Proc Natl Acad Sci U S A. 1993 Nov 1;90(21):9808–9812. [PubMed]
  • Dawson VL, Dawson TM, London ED, Bredt DS, Snyder SH. Nitric oxide mediates glutamate neurotoxicity in primary cortical cultures. Proc Natl Acad Sci U S A. 1991 Jul 15;88(14):6368–6371. [PubMed]
  • Hanbauer I, Wink D, Osawa Y, Edelman GM, Gally JA. Role of nitric oxide in NMDA-evoked release of [3H]-dopamine from striatal slices. Neuroreport. 1992 May;3(5):409–412. [PubMed]
  • Hirsch DB, Steiner JP, Dawson TM, Mammen A, Hayek E, Snyder SH. Neurotransmitter release regulated by nitric oxide in PC-12 cells and brain synaptosomes. Curr Biol. 1993 Nov 1;3(11):749–754. [PubMed]
  • Llinás R, McGuinness TL, Leonard CS, Sugimori M, Greengard P. Intraterminal injection of synapsin I or calcium/calmodulin-dependent protein kinase II alters neurotransmitter release at the squid giant synapse. Proc Natl Acad Sci U S A. 1985 May;82(9):3035–3039. [PubMed]
  • Llinás R, Gruner JA, Sugimori M, McGuinness TL, Greengard P. Regulation by synapsin I and Ca(2+)-calmodulin-dependent protein kinase II of the transmitter release in squid giant synapse. J Physiol. 1991 May;436:257–282. [PubMed]
  • Nichols RA, Chilcote TJ, Czernik AJ, Greengard P. Synapsin I regulates glutamate release from rat brain synaptosomes. J Neurochem. 1992 Feb;58(2):783–785. [PubMed]
  • Laemmli UK. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature. 1970 Aug 15;227(5259):680–685. [PubMed]
  • Schreiber SL. Chemistry and biology of the immunophilins and their immunosuppressive ligands. Science. 1991 Jan 18;251(4991):283–287. [PubMed]
  • Hultsch T, Albers MW, Schreiber SL, Hohman RJ. Immunophilin ligands demonstrate common features of signal transduction leading to exocytosis or transcription. Proc Natl Acad Sci U S A. 1991 Jul 15;88(14):6229–6233. [PubMed]
  • Sandberg K, Berry CJ, Eugster E, Rogers TB. A role for cGMP during tetanus toxin blockade of acetylcholine release in the rat pheochromocytoma (PC12) cell line. J Neurosci. 1989 Nov;9(11):3946–3954. [PubMed]
  • Sandberg K, Berry CJ, Rogers TB. Studies on the intoxication pathway of tetanus toxin in the rat pheochromocytoma (PC12) cell line. Binding, internalization, and inhibition of acetylcholine release. J Biol Chem. 1989 Apr 5;264(10):5679–5686. [PubMed]
  • Dinerman JL, Steiner JP, Dawson TM, Dawson V, Snyder SH. Cyclic nucleotide dependent phosphorylation of neuronal nitric oxide synthase inhibits catalytic activity. Neuropharmacology. 1994 Nov;33(11):1245–1251. [PubMed]
  • Marin P, Lafon-Cazal M, Bockaert J. A Nitric Oxide Synthase Activity Selectively Stimulated by NMDA Receptors Depends on Protein Kinase C Activation in Mouse Striatal Neurons. Eur J Neurosci. 1992;4(5):425–432. [PubMed]
  • King MM, Huang CY, Chock PB, Nairn AC, Hemmings HC, Jr, Chan KF, Greengard P. Mammalian brain phosphoproteins as substrates for calcineurin. J Biol Chem. 1984 Jul 10;259(13):8080–8083. [PubMed]
  • Nichols RA, Suplick GR, Brown JM. Calcineurin-mediated protein dephosphorylation in brain nerve terminals regulates the release of glutamate. J Biol Chem. 1994 Sep 23;269(38):23817–23823. [PubMed]
  • Liu JP, Sim AT, Robinson PJ. Calcineurin inhibition of dynamin I GTPase activity coupled to nerve terminal depolarization. Science. 1994 Aug 12;265(5174):970–973. [PubMed]
  • Mulkey RM, Endo S, Shenolikar S, Malenka RC. Involvement of a calcineurin/inhibitor-1 phosphatase cascade in hippocampal long-term depression. Nature. 1994 Jun 9;369(6480):486–488. [PubMed]
  • Lyson T, Ermel LD, Belshaw PJ, Alberg DG, Schreiber SL, Victor RG. Cyclosporine- and FK506-induced sympathetic activation correlates with calcineurin-mediated inhibition of T-cell signaling. Circ Res. 1993 Sep;73(3):596–602. [PubMed]

Articles from Molecular Medicine are provided here courtesy of The Feinstein Institute for Medical Research at North Shore LIJ