1
|
Olivares MJ, González-Jamett AM, Guerra MJ, Baez-Matus X, Haro-Acuña V, Martínez-Quiles N, Cárdenas AM. Src kinases regulate de novo actin polymerization during exocytosis in neuroendocrine chromaffin cells. PLoS One 2014; 9:e99001. [PMID: 24901433 PMCID: PMC4047038 DOI: 10.1371/journal.pone.0099001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 05/09/2014] [Indexed: 11/19/2022] Open
Abstract
The cortical actin network is dynamically rearranged during secretory processes. Nevertheless, it is unclear how de novo actin polymerization and the disruption of the preexisting actin network control transmitter release. Here we show that in bovine adrenal chromaffin cells, both formation of new actin filaments and disruption of the preexisting cortical actin network are induced by Ca2+ concentrations that trigger exocytosis. These two processes appear to regulate different stages of exocytosis; whereas the inhibition of actin polymerization with the N-WASP inhibitor wiskostatin restricts fusion pore expansion, thus limiting the release of transmitters, the disruption of the cortical actin network with cytochalasin D increases the amount of transmitter released per event. Further, the Src kinase inhibitor PP2, and cSrc SH2 and SH3 domains also suppress Ca2+-dependent actin polymerization, and slow down fusion pore expansion without disturbing the cortical F-actin organization. Finally, the isolated SH3 domain of c-Src prevents both the disruption of the actin network and the increase in the quantal release induced by cytochalasin D. These findings support a model where a rise in the cytosolic Ca2+ triggers actin polymerization through a mechanism that involves Src kinases. The newly formed actin filaments would speed up the expansion of the initial fusion pore, whereas the preexisting actin network might control a different step of the exocytosis process.
Collapse
Affiliation(s)
- María José Olivares
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Playa Ancha, Valparaíso, Chile
| | - Arlek M. González-Jamett
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Playa Ancha, Valparaíso, Chile
| | - María José Guerra
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Playa Ancha, Valparaíso, Chile
| | - Ximena Baez-Matus
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Playa Ancha, Valparaíso, Chile
| | - Valentina Haro-Acuña
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Playa Ancha, Valparaíso, Chile
| | - Narcisa Martínez-Quiles
- Departamento de Microbiología (Inmunología), Facultad de Medicina, Universidad Complutense de Madrid, Madrid, Spain
| | - Ana M. Cárdenas
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Playa Ancha, Valparaíso, Chile
- * E-mail:
| |
Collapse
|
2
|
Schober A, Sokolova E, Gingrich KJ. Pentobarbital inhibition of human recombinant alpha1A P/Q-type voltage-gated calcium channels involves slow, open channel block. Br J Pharmacol 2011; 161:365-83. [PMID: 20735421 DOI: 10.1111/j.1476-5381.2010.00886.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Pre-synaptic neurotransmitter release is largely dependent on Ca(2+) entry through P/Q-type (Ca(V)2.1) voltage-gated Ca(2+) channels (PQCCs) at most mammalian, central, fast synapses. Barbiturates are clinical depressants and inhibit pre-synaptic Ca(2+) entry. PQCC barbiturate pharmacology is generally unclear, specifically in man. The pharmacology of the barbiturate pentobarbital (PB) in human recombinant alpha(1A) PQCCs has been characterized. EXPERIMENTAL APPROACH PB effects on macroscopic Ca(2+)(I(Ca)) and Ba(2+)(I(Ba)) currents were studied using whole-cell patch clamp recording in HEK-293 cells heterologously expressing (alpha(1A))(human)(beta(2a)alpha(2)delta-1)(rabbit) PQCCs. KEY RESULTS PB reversibly depressed peak current (I(peak)) and enhanced apparent inactivation (fractional current at 800 ms, r(800)) in a concentration-dependent fashion irrespective of charge carrier (50% inhibitory concentration: I(peak), 656 microM; r(800), 104 microM). Rate of mono-exponential I(Ba) decay was linearly dependent on PB concentration. PB reduced channel availability by deepening non-steady-state inactivation curves without altering voltage dependence, slowed recovery from activity-induced unavailable states and produced use-dependent block. PB (100 microM) induced use-dependent block during physiological, high frequency pulse trains and overall depressed PQCC activity by two-fold. CONCLUSION AND IMPLICATIONS The results support a PB pharmacological mechanism involving a modulated receptor with preferential slow, bimolecular, open channel block (K(d)= 15 microM). Clinical PB concentrations (<200 microM) inhibit PQCC during high frequency activation that reduces computed neurotransmitter release by 16-fold and is comparable to the magnitude of Ca(2+)-dependent facilitation, G-protein modulation and intrinsic inactivation that play critical roles in PQCC modulation underlying synaptic plasticity. The results are consistent with the hypothesis that PB inhibition of PQCCs contributes to central nervous system depression underlying anticonvulsant therapy and general anaesthesia.
Collapse
Affiliation(s)
- A Schober
- The Department of Anesthesiology, New York University Langone Medical Center, New York, NY 10016, USA
| | | | | |
Collapse
|
3
|
Rosa JM, Gandía L, García AG. Inhibition of N and PQ calcium channels by calcium entry through L channels in chromaffin cells. Pflugers Arch 2009; 458:795-807. [PMID: 19347353 DOI: 10.1007/s00424-009-0662-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Revised: 02/09/2009] [Accepted: 03/01/2009] [Indexed: 11/24/2022]
Abstract
Why adrenal chromaffin cells express various subtypes of voltage-dependent Ca(2+) channels and whether a given channel is specialized to perform a specific function are puzzling and unanswered questions. In this study, we have used the L Ca(2+) channel activator FPL64176 (FPL) to test the hypothesis that enhanced Ca(2+) entry through this channel favors the inhibition of N and PQ channels in voltage-clamped bovine adrenal chromaffin cells. Using 2 mM Ca(2+) as charge carrier and under the perforated-patch configuration (PPC) of the patch-clamp technique, FPL caused a paradoxical inhibition of the whole-cell inward Ca(2+) current (I (Ca)). Such inhibition turned on into an augmentation upon cell loading with EGTA-AM. Also, under the whole-cell configuration (WCC) of the patch-clamp technique, FPL decreased I (Ca) in the absence of EGTA from the pipette solution and increased the current in its presence. Using 2 mM Ba(2+) as charge carrier, FPL augmented the Ba(2+) current under both recording conditions, WCC and PPC. FPL augmented the residual current remaining after blockade of N and PQ channels with omega-conotoxin MVIIC or by holding the membrane potential at -50 mV. The data support the view that Ca(2+) entering the cell through the lesser inactivating L channels serves to modulate the more inactivating N and PQ channels. They also suggest a close colocalization of L and N/PQ Ca(2+) channels. This kind of L channel specialization may be relevant to cell excitability, exocytosis, and cell survival mechanisms.
Collapse
Affiliation(s)
- Juliana M Rosa
- Instituto Teófilo Hernando, Facultad de Medicina, Universidad Autónoma de Madrid, Arzobispo Morcillo, 4. 28029, Madrid, Spain
| | | | | |
Collapse
|
4
|
Héraud C, Chevrier L, Meunier AC, Muller JM, Chadéneau C. Vasoactive intestinal peptide-induced neuritogenesis in neuroblastoma SH-SY5Y cells involves SNAP-25. Neuropeptides 2008; 42:611-21. [PMID: 18617262 DOI: 10.1016/j.npep.2008.05.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Accepted: 05/24/2008] [Indexed: 12/11/2022]
Abstract
Vasoactive intestinal peptide (VIP) is a neuropeptide known to regulate proliferation and differentiation in normal and tumoral cells. We previously reported that VIP induced neuritogenesis in human neuroblastoma SH-SY5Y cells cultured in serum-free medium. This neuritogenesis was associated with a regulated expression of neuronal cytoskeleton markers. To further characterize the neuroblastic cell differentiation induced by VIP in human SH-SY5Y cells, we investigated expression of synaptosomal-associated protein of 25 kDa (SNAP-25), a protein implicated in exocytosis associated with different processes, including neurite outgrowth. Western immunoblotting and real-time RT-PCR analyses revealed that VIP increased expression of the SNAP-25 protein and the level of both SNAP-25a and SNAP-25b mRNA isoforms. Immunofluorescence experiments indicated that SNAP-25 was mainly located in neurites and at the plasma membrane in SH-SY5Y cells treated with VIP. RNA interference experiments demonstrated that SNAP-25 was involved in VIP-induced neuritogenesis. In conclusion, SNAP-25 is up-regulated and implicated in neuritogenesis in human neuroblastoma SH-SY5Y cells treated with the neuropeptide VIP.
Collapse
Affiliation(s)
- Céline Héraud
- Institut de Physiologie et Biologie Cellulaires, Université de Poitiers, CNRS UMR 6187, Pôle Biologie Santé, Faculté des Sciences Fondamentales et Appliquées, 40 Avenue du Recteur Pineau, Poitiers Cedex F-86022, France
| | | | | | | | | |
Collapse
|
5
|
García AG, García-De-Diego AM, Gandía L, Borges R, García-Sancho J. Calcium Signaling and Exocytosis in Adrenal Chromaffin Cells. Physiol Rev 2006; 86:1093-131. [PMID: 17015485 DOI: 10.1152/physrev.00039.2005] [Citation(s) in RCA: 259] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
At a given cytosolic domain of a chromaffin cell, the rate and amplitude of the Ca2+concentration ([Ca2+]c) depends on at least four efficient regulatory systems: 1) plasmalemmal calcium channels, 2) endoplasmic reticulum, 3) mitochondria, and 4) chromaffin vesicles. Different mammalian species express different levels of the L, N, P/Q, and R subtypes of high-voltage-activated calcium channels; in bovine and humans, P/Q channels predominate, whereas in felines and murine species, L-type channels predominate. The calcium channels in chromaffin cells are regulated by G proteins coupled to purinergic and opiate receptors, as well as by voltage and the local changes of [Ca2+]c. Chromaffin cells have been particularly useful in studying calcium channel current autoregulation by materials coreleased with catecholamines, such as ATP and opiates. Depending on the preparation (cultured cells, adrenal slices) and the stimulation pattern (action potentials, depolarizing pulses, high K+, acetylcholine), the role of each calcium channel in controlling catecholamine release can change drastically. Targeted aequorin and confocal microscopy shows that Ca2+entry through calcium channels can refill the endoplasmic reticulum (ER) to nearly millimolar concentrations, and causes the release of Ca2+(CICR). Depending on its degree of filling, the ER may act as a sink or source of Ca2+that modulates catecholamine release. Targeted aequorins with different Ca2+affinities show that mitochondria undergo surprisingly rapid millimolar Ca2+transients, upon stimulation of chromaffin cells with ACh, high K+, or caffeine. Physiological stimuli generate [Ca2+]cmicrodomains in which the local subplasmalemmal [Ca2+]crises abruptly from 0.1 to ∼50 μM, triggering CICR, mitochondrial Ca2+uptake, and exocytosis at nearby secretory active sites. The fact that protonophores abolish mitochondrial Ca2+uptake, and increase catecholamine release three- to fivefold, support the earlier observation. This increase is probably due to acceleration of vesicle transport from a reserve pool to a ready-release vesicle pool; this transport might be controlled by Ca2+redistribution to the cytoskeleton, through CICR, and/or mitochondrial Ca2+release. We propose that chromaffin cells have developed functional triads that are formed by calcium channels, the ER, and the mitochondria and locally control the [Ca2+]cthat regulate the early and late steps of exocytosis.
Collapse
Affiliation(s)
- Antonio G García
- Instituto Teófilo Hernando, Departamento de Farmacología y Terapéutica, and Servicio de Farmacología Clínica e Instituto Universitario de Investigación Gerontológica y Metabólica, Hospital Universitario de la Princesa, Madrid, Spain.
| | | | | | | | | |
Collapse
|
6
|
Burré J, Beckhaus T, Corvey C, Karas M, Zimmermann H, Volknandt W. Synaptic vesicle proteins under conditions of rest and activation: Analysis by 2-D difference gel electrophoresis. Electrophoresis 2006; 27:3488-96. [PMID: 16944461 DOI: 10.1002/elps.200500864] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Synaptic vesicles are organelles of the nerve terminal that secrete neurotransmitters by fusion with the presynaptic plasma membrane. Vesicle fusion is tightly controlled by depolarization of the plasma membrane and a set of proteins that may undergo post-translational modifications such as phosphorylation. In order to identify proteins that undergo modifications as a result of synaptic activation, we induced massive exocytosis and analysed the synaptic vesicle compartment by benzyldimethyl-n-hexadecylammonium chloride (BAC)/SDS-PAGE and difference gel electrophoresis (DIGE) followed by MALDI-TOF-MS. We identified eight proteins that revealed significant changes in abundance following nerve terminal depolarization. Of these, six were increased and two were decreased in abundance. Three of these proteins were phosphorylated as detected by Western blot analysis. In addition, we identified an unknown synaptic vesicle protein whose abundance increased on synaptic activation. Our results demonstrate that depolarization of the presynaptic compartment induces changes in the abundance of synaptic vesicle proteins and post-translational protein modification.
Collapse
Affiliation(s)
- Jacqueline Burré
- Department of Neurochemistry, JW Goethe-University, Frankfurt/Main, Germany.
| | | | | | | | | | | |
Collapse
|
7
|
Sakurai T, Satake A, Sumi S, Inoue K, Miyakoshi J. An extremely low frequency magnetic field attenuates insulin secretion from the insulinoma cell line, RIN-m. Bioelectromagnetics 2004; 25:160-6. [PMID: 15042624 DOI: 10.1002/bem.10181] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In this study, we investigated the effects of exposure to an extremely low frequency magnetic field (ELFMF) on hormone secretion from an islet derived insulinoma cell line, RIN-m. We stimulated RIN-m cells to secrete insulin under exposure to an ELFMF, using our established system for the exposure of cultured cells to an ELFMF at 5 mT and 60 Hz, or under sham exposure conditions for 1 h and observed the effects. In the presence of a depolarizing concentration of potassium (45 mM KCl), exposure to ELFMF significantly attenuated insulin release from RIN-m cells, compared to sham exposed cells. Treatment with nifedipine reduced the difference in insulin secretion between cells exposed to an ELFMF and sham exposed cells. The expression of mRNA encoding synaptosomal associated protein of 25 kDa (SNAP-25) and synaptotagmin 1, which play a role in exocytosis in hormone secretion and influx of calcium ions, decreased with exposure to an ELFMF in the presence of 45 mM KCl. These results suggest that exposure to ELFMF attenuates insulin secretion from RIN-m cells by affecting calcium influx through calcium channels.
Collapse
Affiliation(s)
- Tomonori Sakurai
- Department of Organ Reconstruction, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan
| | | | | | | | | |
Collapse
|
8
|
Mendoza IE, Schmachtenberg O, Tonk E, Fuentealba J, Díaz-Raya P, Lagos VL, García AG, Cárdenas AM. Depolarization-induced ERK phosphorylation depends on the cytosolic Ca2+ level rather than on the Ca2+ channel subtype of chromaffin cells. J Neurochem 2003; 86:1477-86. [PMID: 12950456 DOI: 10.1046/j.1471-4159.2003.01965.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The contribution of Ca2+ entry through different voltage-activated Ca2+ channel (VACC) subtypes to the phosphorylation of extracellular signal regulated kinase (ERK) was examined in bovine adrenal-medullary chromaffin cells. High K+ depolarization (40 mM, 3 min) induced ERK phosphorylation, an effect that was inhibited by specific mitogen-activated protein kinase kinase inhibitors. By using selective inhibitors, we observed that depolarization-induced ERK phosphorylation completely depended on protein kinase C-alpha (PKC-alpha), but not on Ca2+/calmodulin-dependent protein kinase nor cyclic AMP-dependent protein kinase. Blockade of L-type Ca2+ channels by 3 microm furnidipine, or blockade of N channels by 1 micromomega-conotoxin GVIA reduced ERK phosphorylation by 70%, while the inhibition of P/Q channels by 1 micromomega-agatoxin IVA only caused a 40% reduction. The simultaneous blockade of L and N, or P/Q and N channels completely abolished this response, yet 23% ERK phosphorylation remained when L and P/Q channels were simultaneously blocked. Confocal imaging of cytosolic Ca2+ elevations elicited by 40 mm K+, showed that Ca2+ levels increased throughout the entire cytosol, both in the presence and the absence of Ca2+ channel blockers. Fifty-eight percent of the fluorescence rise depended on Ca2+ entering through N channels. Thus, ERK phosphorylation seems to depend on a critical level of Ca2+ in the cytosol rather than on activation of a given Ca2+ channel subtype.
Collapse
Affiliation(s)
- Isabel E Mendoza
- Centro de Neurociencia de Valparaíso, Universidad de Valparaíso, Chile
| | | | | | | | | | | | | | | |
Collapse
|
9
|
Montiel C, Mendoza I, García CJ, Awad Y, García-Olivares J, Solís-Garrido LM, Lara H, García AG, Cárdenas AM. Distinct protein kinases regulate SNAP-25 expression in chromaffin cells. J Neurosci Res 2003; 71:353-64. [PMID: 12526024 DOI: 10.1002/jnr.10499] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The contribution of distinct Ca(2+)-sensitive protein kinases to the regulation of the expression of the synaptosomal-associated protein SNAP-25 was examined in bovine chromaffin cells. Prolonged incubation with high K(+) (38 mM) or 1,1-dimethyl-4-phenyl-piperazinium (DMPP), a nicotinic receptor agonist, significantly increased SNAP-25 protein and mRNA expression, as assessed by immunoblotting and semi-quantitative RT-PCR analysis. Both stimuli preferentially enhanced mRNA coding for the SNAP-25a isoform. Increase of SNAP-25 expression induced by K(+) or DMPP was inhibited over 70% by KN-62 and KN-93, two Ca(2+)/calmodulin-dependent protein kinase (CaMK) inhibitors, whereas the inactive analogue KN-92 only reduced the expression by 34%. The three compounds also inhibited the high K(+)-elicited [Ca(2+)](i) signal by 40%, suggesting that the effect of KN-62 and KN-93 was a combination of CaMK/ Ca(2+) influx inhibitory actions. Incubation of the cells with mitogen-activated protein kinase (MAPK) inhibitors PD98059 and U0126 reduced protein expression elicited by high K(+) by 50%, but did not modify the response to DMPP. Interestingly, although protein kinase A (PKA) inhibition by H-89 did not affect the high K(+) or DMPP-induced SNAP-25 expression, basal protein levels were significantly modified upon activation or inhibition of this pathway. Basal expression of SNAP-25 was also modified by the protein kinase C (PKC) activator, phorbol 12-myristate 13-acetate, but not by Gö6976, a PKC-alpha inhibitor, suggesting that the Ca(2+)-insensitive PKC-epsilon isoform control basal expression of SNAP-25 in these cells. Taken together, these results provide the first evidence that diverse protein kinases might converge in the induction of SNAP-25 expression in chromaffin cells. The preferential contribution of one or another kinase would depend on the physiological or experimental conditions.
Collapse
Affiliation(s)
- Carmen Montiel
- Departamento de Farmacología, Facultad de Medicina, Universidad Autónoma de Madrid, Spain
| | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Mendoza I, Tonk E, Díaz-Raya P, Cárdenas AM. Mitogen-activated protein kinase is activated by Ca(2+) entry through L- and N-type channels and regulates Ca(2+)-induced SNAP-25 expression. Ann N Y Acad Sci 2002; 971:159-61. [PMID: 12438111 DOI: 10.1111/j.1749-6632.2002.tb04455.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Isabel Mendoza
- Centro de Neurociencia Molecular y Celular de Valparaiso, Escuela de Medicina, Universidad de Valparaiso, Valparaiso, Chile
| | | | | | | |
Collapse
|
11
|
Allen DD, Cárdenas AM, Arriagada C, Bennett LB, García CJ, Caviedes R, Rapoport SI, Caviedes P. A dorsal root ganglia cell line derived from trisomy 16 fetal mice, a model for Down syndrome. Neuroreport 2002; 13:491-6. [PMID: 11930168 DOI: 10.1097/00001756-200203250-00027] [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: 11/26/2022]
Abstract
We have established two immortalized cell lines from dorsal root ganglia of normal (G4b) and trisomy 16 mice (GT1), a model for Down syndrome. By immunohistochemistry, both cell lines exhibit neuronal traits and lack glial markers. GTl cells exhibited greater [3H]choline uptake than G4b cells. K+ and nicotine-mediated acetylcholine release was greater in GT1 cells. Basal intracellular Ca2+ concentration ([Ca2+]i) was significantly lower in GTl cells. More GTl cells responded to neurotransmitters with a transient [Ca2+]i increase compared to G4b cells, but both cell types showed similar amplitudes of [Ca2+]i responses. The results show that both cell lines retain neuronal characteristics and respond to specific neurotransmitter stimuli. Altered GT1 cell responses could be related to neuronal pathophysiology in Down's syndrome.
Collapse
Affiliation(s)
- David D Allen
- Department of Pharmaceutical Sciences, Texas Tech University HSC, Amarillo, Texas, USA
| | | | | | | | | | | | | | | |
Collapse
|
12
|
Hepp R, Dupont JL, Aunis D, Langley K, Grant NJ. NGF enhances depolarization effects on SNAP-25 expression: induction of SNAP-25b isoform. Neuroreport 2001; 12:673-7. [PMID: 11277561 DOI: 10.1097/00001756-200103260-00011] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The 25 kDa synaptosomal associated protein (SNAP-25), which is implicated in neuronal plasticity and neurosecretion, exists as two isoforms generated by alternative splicing of exons 5a and 5b. The aim of the present study was to characterize factors influencing isoform expression. We report that chronic depolarization of PC12 cells alone or in the presence of NGF induces the expression of isoform-b, in addition to a 1.8- to 3-fold increase in SNAP-25 mRNA and protein as determined by immunoblotting and combined RT-PCR and Southern blot analysis. When cerebellar granule neurons were cultured in elevated K+, the predominant isoform switched from SNAP-25a to SNAP-25b. Taken together these results suggested that chronic depolarization regulates the transcription and processing of SNAP-25 mRNA.
Collapse
Affiliation(s)
- R Hepp
- INSERM Unité 338, Biologie de la Communication Cellulaire and CNRS FRE 2180, Strasbourg, France
| | | | | | | | | |
Collapse
|