Calcium homeostasis and cone signaling are regulated by interactions between calcium stores and plasma membrane ion channels.
Calcium is a messenger ion that controls all aspects of cone photoreceptor function, including synaptic release. The dynamic range of the cone output extends beyond the activation threshold for voltage-operated calcium entry, suggesting another calcium influx mechanism operates in cones hyperpolariz...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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Public Library of Science (PLoS)
2009-08-01
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| Series: | PLoS ONE |
| Online Access: | http://europepmc.org/articles/PMC2725299?pdf=render |
| _version_ | 1828305530050838528 |
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| author | Tamas Szikra Peter Barabas Theodore M Bartoletti Wei Huang Abram Akopian Wallace B Thoreson David Krizaj |
| author_facet | Tamas Szikra Peter Barabas Theodore M Bartoletti Wei Huang Abram Akopian Wallace B Thoreson David Krizaj |
| author_sort | Tamas Szikra |
| collection | DOAJ |
| description | Calcium is a messenger ion that controls all aspects of cone photoreceptor function, including synaptic release. The dynamic range of the cone output extends beyond the activation threshold for voltage-operated calcium entry, suggesting another calcium influx mechanism operates in cones hyperpolarized by light. We have used optical imaging and whole-cell voltage clamp to measure the contribution of store-operated Ca(2+) entry (SOCE) to Ca(2+) homeostasis and its role in regulation of neurotransmission at cone synapses. Mn(2+) quenching of Fura-2 revealed sustained divalent cation entry in hyperpolarized cones. Ca(2+) influx into cone inner segments was potentiated by hyperpolarization, facilitated by depletion of intracellular Ca(2+) stores, unaffected by pharmacological manipulation of voltage-operated or cyclic nucleotide-gated Ca(2+) channels and suppressed by lanthanides, 2-APB, MRS 1845 and SKF 96365. However, cation influx through store-operated channels crossed the threshold for activation of voltage-operated Ca(2+) entry in a subset of cones, indicating that the operating range of inner segment signals is set by interactions between store- and voltage-operated Ca(2+) channels. Exposure to MRS 1845 resulted in approximately 40% reduction of light-evoked postsynaptic currents in photopic horizontal cells without affecting the light responses or voltage-operated Ca(2+) currents in simultaneously recorded cones. The spatial pattern of store-operated calcium entry in cones matched immunolocalization of the store-operated sensor STIM1. These findings show that store-operated channels regulate spatial and temporal properties of Ca(2+) homeostasis in vertebrate cones and demonstrate their role in generation of sustained excitatory signals across the first retinal synapse. |
| first_indexed | 2024-04-13T14:31:11Z |
| format | Article |
| id | doaj.art-ebbf04a5f5ac461893d482d8a6fdb5f2 |
| institution | Directory Open Access Journal |
| issn | 1932-6203 |
| language | English |
| last_indexed | 2024-04-13T14:31:11Z |
| publishDate | 2009-08-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS ONE |
| spelling | doaj.art-ebbf04a5f5ac461893d482d8a6fdb5f22022-12-22T02:43:12ZengPublic Library of Science (PLoS)PLoS ONE1932-62032009-08-0148e672310.1371/journal.pone.0006723Calcium homeostasis and cone signaling are regulated by interactions between calcium stores and plasma membrane ion channels.Tamas SzikraPeter BarabasTheodore M BartolettiWei HuangAbram AkopianWallace B ThoresonDavid KrizajCalcium is a messenger ion that controls all aspects of cone photoreceptor function, including synaptic release. The dynamic range of the cone output extends beyond the activation threshold for voltage-operated calcium entry, suggesting another calcium influx mechanism operates in cones hyperpolarized by light. We have used optical imaging and whole-cell voltage clamp to measure the contribution of store-operated Ca(2+) entry (SOCE) to Ca(2+) homeostasis and its role in regulation of neurotransmission at cone synapses. Mn(2+) quenching of Fura-2 revealed sustained divalent cation entry in hyperpolarized cones. Ca(2+) influx into cone inner segments was potentiated by hyperpolarization, facilitated by depletion of intracellular Ca(2+) stores, unaffected by pharmacological manipulation of voltage-operated or cyclic nucleotide-gated Ca(2+) channels and suppressed by lanthanides, 2-APB, MRS 1845 and SKF 96365. However, cation influx through store-operated channels crossed the threshold for activation of voltage-operated Ca(2+) entry in a subset of cones, indicating that the operating range of inner segment signals is set by interactions between store- and voltage-operated Ca(2+) channels. Exposure to MRS 1845 resulted in approximately 40% reduction of light-evoked postsynaptic currents in photopic horizontal cells without affecting the light responses or voltage-operated Ca(2+) currents in simultaneously recorded cones. The spatial pattern of store-operated calcium entry in cones matched immunolocalization of the store-operated sensor STIM1. These findings show that store-operated channels regulate spatial and temporal properties of Ca(2+) homeostasis in vertebrate cones and demonstrate their role in generation of sustained excitatory signals across the first retinal synapse.http://europepmc.org/articles/PMC2725299?pdf=render |
| spellingShingle | Tamas Szikra Peter Barabas Theodore M Bartoletti Wei Huang Abram Akopian Wallace B Thoreson David Krizaj Calcium homeostasis and cone signaling are regulated by interactions between calcium stores and plasma membrane ion channels. PLoS ONE |
| title | Calcium homeostasis and cone signaling are regulated by interactions between calcium stores and plasma membrane ion channels. |
| title_full | Calcium homeostasis and cone signaling are regulated by interactions between calcium stores and plasma membrane ion channels. |
| title_fullStr | Calcium homeostasis and cone signaling are regulated by interactions between calcium stores and plasma membrane ion channels. |
| title_full_unstemmed | Calcium homeostasis and cone signaling are regulated by interactions between calcium stores and plasma membrane ion channels. |
| title_short | Calcium homeostasis and cone signaling are regulated by interactions between calcium stores and plasma membrane ion channels. |
| title_sort | calcium homeostasis and cone signaling are regulated by interactions between calcium stores and plasma membrane ion channels |
| url | http://europepmc.org/articles/PMC2725299?pdf=render |
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