PIP2 alters Ca2+ currents in acutely dissociated supraoptic oxytocin neurons
Abstract Magnocellular neurosecretory cells (MNCs) occupying the supraoptic nucleus (SON) contain voltage‐gated Ca2+ channels that provide Ca2+ for triggering vesicle release, initiating signaling pathways, and activating channels, such as the potassium channels underlying the afterhyperpolarization...
| Main Authors: | , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Wiley
2019-08-01
|
| Series: | Physiological Reports |
| Subjects: | |
| Online Access: | https://doi.org/10.14814/phy2.14198 |
| _version_ | 1818250096664379392 |
|---|---|
| author | Matthew K. Kirchner William E. Armstrong Dongxu Guan Yoichi Ueta Robert C. Foehring |
| author_facet | Matthew K. Kirchner William E. Armstrong Dongxu Guan Yoichi Ueta Robert C. Foehring |
| author_sort | Matthew K. Kirchner |
| collection | DOAJ |
| description | Abstract Magnocellular neurosecretory cells (MNCs) occupying the supraoptic nucleus (SON) contain voltage‐gated Ca2+ channels that provide Ca2+ for triggering vesicle release, initiating signaling pathways, and activating channels, such as the potassium channels underlying the afterhyperpolarization (AHP). Phosphotidylinositol 4,5‐bisphosphate (PIP2) is a phospholipid membrane component that has been previously shown to modulate Ca2+ channels, including in the SON in our previous work. In this study, we further investigated the ways in which PIP2 modulates these channels, and for the first time show how PIP2 modulates CaV channel currents in native membranes. Using whole cell patch clamp of genetically labeled dissociated neurons, we demonstrate that PIP2 depletion via wortmannin (0.5 μmol/L) inhibits Ca2+ channel currents in OT but not VP neurons. Additionally, it hyperpolarizes voltage‐dependent activation of the channels by ~5 mV while leaving the slope of activation unchanged, properties unaffected in VP neurons. We also identified key differences in baseline currents between the cell types, wherein VP whole cell Ca2+ currents display more inactivation and shorter deactivation time constants. Wortmannin accelerates inactivation of Ca2+ channels in OT neurons, which we show to be mostly an effect on N‐type Ca2+ channels. Finally, we demonstrate that wortmannin prevents prepulse‐induced facilitation of peak Ca2+ channel currents. We conclude that PIP2 is a modulator that enhances current through N‐type channels. This has implications for the afterhyperpolarization (AHP) of OT neurons, as previous work from our laboratory demonstrated the AHP is inhibited by wortmannin, and that its primary activation is from intracellular Ca2+ contributed by N‐type channels. |
| first_indexed | 2024-12-12T15:46:57Z |
| format | Article |
| id | doaj.art-edae4f5dab6b4dc6832e4ead55b3ef99 |
| institution | Directory Open Access Journal |
| issn | 2051-817X |
| language | English |
| last_indexed | 2024-12-12T15:46:57Z |
| publishDate | 2019-08-01 |
| publisher | Wiley |
| record_format | Article |
| series | Physiological Reports |
| spelling | doaj.art-edae4f5dab6b4dc6832e4ead55b3ef992022-12-22T00:19:43ZengWileyPhysiological Reports2051-817X2019-08-01716n/an/a10.14814/phy2.14198PIP2 alters Ca2+ currents in acutely dissociated supraoptic oxytocin neuronsMatthew K. Kirchner0William E. Armstrong1Dongxu Guan2Yoichi Ueta3Robert C. Foehring4Department of Anatomy and Physiology University of Tennessee Health Science Center Memphis TennesseeDepartment of Anatomy and Physiology University of Tennessee Health Science Center Memphis TennesseeDepartment of Anatomy and Physiology University of Tennessee Health Science Center Memphis TennesseeDepartment of Physiology, School of Medicine University of Occupational and Environmental Health Kitakyushu JapanDepartment of Anatomy and Physiology University of Tennessee Health Science Center Memphis TennesseeAbstract Magnocellular neurosecretory cells (MNCs) occupying the supraoptic nucleus (SON) contain voltage‐gated Ca2+ channels that provide Ca2+ for triggering vesicle release, initiating signaling pathways, and activating channels, such as the potassium channels underlying the afterhyperpolarization (AHP). Phosphotidylinositol 4,5‐bisphosphate (PIP2) is a phospholipid membrane component that has been previously shown to modulate Ca2+ channels, including in the SON in our previous work. In this study, we further investigated the ways in which PIP2 modulates these channels, and for the first time show how PIP2 modulates CaV channel currents in native membranes. Using whole cell patch clamp of genetically labeled dissociated neurons, we demonstrate that PIP2 depletion via wortmannin (0.5 μmol/L) inhibits Ca2+ channel currents in OT but not VP neurons. Additionally, it hyperpolarizes voltage‐dependent activation of the channels by ~5 mV while leaving the slope of activation unchanged, properties unaffected in VP neurons. We also identified key differences in baseline currents between the cell types, wherein VP whole cell Ca2+ currents display more inactivation and shorter deactivation time constants. Wortmannin accelerates inactivation of Ca2+ channels in OT neurons, which we show to be mostly an effect on N‐type Ca2+ channels. Finally, we demonstrate that wortmannin prevents prepulse‐induced facilitation of peak Ca2+ channel currents. We conclude that PIP2 is a modulator that enhances current through N‐type channels. This has implications for the afterhyperpolarization (AHP) of OT neurons, as previous work from our laboratory demonstrated the AHP is inhibited by wortmannin, and that its primary activation is from intracellular Ca2+ contributed by N‐type channels.https://doi.org/10.14814/phy2.14198Ca2+ channelsoxytocinPIP2supraoptic nucleus |
| spellingShingle | Matthew K. Kirchner William E. Armstrong Dongxu Guan Yoichi Ueta Robert C. Foehring PIP2 alters Ca2+ currents in acutely dissociated supraoptic oxytocin neurons Physiological Reports Ca2+ channels oxytocin PIP2 supraoptic nucleus |
| title | PIP2 alters Ca2+ currents in acutely dissociated supraoptic oxytocin neurons |
| title_full | PIP2 alters Ca2+ currents in acutely dissociated supraoptic oxytocin neurons |
| title_fullStr | PIP2 alters Ca2+ currents in acutely dissociated supraoptic oxytocin neurons |
| title_full_unstemmed | PIP2 alters Ca2+ currents in acutely dissociated supraoptic oxytocin neurons |
| title_short | PIP2 alters Ca2+ currents in acutely dissociated supraoptic oxytocin neurons |
| title_sort | pip2 alters ca2 currents in acutely dissociated supraoptic oxytocin neurons |
| topic | Ca2+ channels oxytocin PIP2 supraoptic nucleus |
| url | https://doi.org/10.14814/phy2.14198 |
| work_keys_str_mv | AT matthewkkirchner pip2altersca2currentsinacutelydissociatedsupraopticoxytocinneurons AT williamearmstrong pip2altersca2currentsinacutelydissociatedsupraopticoxytocinneurons AT dongxuguan pip2altersca2currentsinacutelydissociatedsupraopticoxytocinneurons AT yoichiueta pip2altersca2currentsinacutelydissociatedsupraopticoxytocinneurons AT robertcfoehring pip2altersca2currentsinacutelydissociatedsupraopticoxytocinneurons |