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Imaging of Endoplasmic Reticulum Ca(2+) in the Intact Pituitary Gland of Transgenic Mice Expressing a Low Affinity Ca(2+) Indicator

The adenohypophysis contains five secretory cell types (somatotrophs, lactotrophs, thyrotrophs, corticotrophs, and gonadotrophs), each secreting a different hormone, and controlled by different hypothalamic releasing hormones (HRHs). Exocytic secretion is regulated by cytosolic Ca(2+) signals ([Ca(2...

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Autores principales: Rojo-Ruiz, Jonathan, Navas-Navarro, Paloma, Nuñez, Lucía, García-Sancho, Javier, Alonso, María Teresa
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Frontiers Media S.A. 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7921146/
https://www.ncbi.nlm.nih.gov/pubmed/33664709
http://dx.doi.org/10.3389/fendo.2020.615777
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author Rojo-Ruiz, Jonathan
Navas-Navarro, Paloma
Nuñez, Lucía
García-Sancho, Javier
Alonso, María Teresa
author_facet Rojo-Ruiz, Jonathan
Navas-Navarro, Paloma
Nuñez, Lucía
García-Sancho, Javier
Alonso, María Teresa
author_sort Rojo-Ruiz, Jonathan
collection PubMed
description The adenohypophysis contains five secretory cell types (somatotrophs, lactotrophs, thyrotrophs, corticotrophs, and gonadotrophs), each secreting a different hormone, and controlled by different hypothalamic releasing hormones (HRHs). Exocytic secretion is regulated by cytosolic Ca(2+) signals ([Ca(2+)](C)), which can be generated either by Ca(2+) entry through the plasma membrane and/or by Ca(2+) release from the endoplasmic reticulum (ER). In addition, Ca(2+) entry signals can eventually be amplified by ER release via calcium-induced calcium release (CICR). We have investigated the contribution of ER Ca(2+) release to the action of physiological agonists in pituitary gland. Changes of [Ca(2+)] in the ER ([Ca(2+)](ER)) were measured with the genetically encoded low-affinity Ca(2+) sensor GAP3 targeted to the ER. We used a transgenic mouse strain that expressed erGAP3 driven by a ubiquitous promoter. Virtually all the pituitary cells were positive for the sensor. In order to mimick the physiological environment, intact pituitary glands or acute slices from the transgenic mouse were used to image [Ca(2+)](ER). [Ca(2+)](C) was measured simultaneously with Rhod-2. Luteinizing hormone-releasing hormone (LHRH) or thyrotropin releasing hormone (TRH), two agonists known to elicit intracellular Ca(2+) mobilization, provoked robust decreases of [Ca(2+)](ER) and concomitant rises of [Ca(2+)](C). A smaller fraction of cells responded to thyrotropin releasing hormone (TRH). By contrast, depolarization with high K(+) triggered a rise of [Ca(2+)](C) without a decrease of [Ca(2+)](ER), indicating that the calcium-induced calcium-release (CICR) via ryanodine receptor amplification mechanism is not present in these cells. Our results show the potential of transgenic ER Ca(2+) indicators as novel tools to explore intraorganellar Ca(2+) dynamics in pituitary gland in situ.
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spelling pubmed-79211462021-03-03 Imaging of Endoplasmic Reticulum Ca(2+) in the Intact Pituitary Gland of Transgenic Mice Expressing a Low Affinity Ca(2+) Indicator Rojo-Ruiz, Jonathan Navas-Navarro, Paloma Nuñez, Lucía García-Sancho, Javier Alonso, María Teresa Front Endocrinol (Lausanne) Endocrinology The adenohypophysis contains five secretory cell types (somatotrophs, lactotrophs, thyrotrophs, corticotrophs, and gonadotrophs), each secreting a different hormone, and controlled by different hypothalamic releasing hormones (HRHs). Exocytic secretion is regulated by cytosolic Ca(2+) signals ([Ca(2+)](C)), which can be generated either by Ca(2+) entry through the plasma membrane and/or by Ca(2+) release from the endoplasmic reticulum (ER). In addition, Ca(2+) entry signals can eventually be amplified by ER release via calcium-induced calcium release (CICR). We have investigated the contribution of ER Ca(2+) release to the action of physiological agonists in pituitary gland. Changes of [Ca(2+)] in the ER ([Ca(2+)](ER)) were measured with the genetically encoded low-affinity Ca(2+) sensor GAP3 targeted to the ER. We used a transgenic mouse strain that expressed erGAP3 driven by a ubiquitous promoter. Virtually all the pituitary cells were positive for the sensor. In order to mimick the physiological environment, intact pituitary glands or acute slices from the transgenic mouse were used to image [Ca(2+)](ER). [Ca(2+)](C) was measured simultaneously with Rhod-2. Luteinizing hormone-releasing hormone (LHRH) or thyrotropin releasing hormone (TRH), two agonists known to elicit intracellular Ca(2+) mobilization, provoked robust decreases of [Ca(2+)](ER) and concomitant rises of [Ca(2+)](C). A smaller fraction of cells responded to thyrotropin releasing hormone (TRH). By contrast, depolarization with high K(+) triggered a rise of [Ca(2+)](C) without a decrease of [Ca(2+)](ER), indicating that the calcium-induced calcium-release (CICR) via ryanodine receptor amplification mechanism is not present in these cells. Our results show the potential of transgenic ER Ca(2+) indicators as novel tools to explore intraorganellar Ca(2+) dynamics in pituitary gland in situ. Frontiers Media S.A. 2021-02-16 /pmc/articles/PMC7921146/ /pubmed/33664709 http://dx.doi.org/10.3389/fendo.2020.615777 Text en Copyright © 2021 Rojo-Ruiz, Navas-Navarro, Nuñez, García-Sancho and Alonso http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
spellingShingle Endocrinology
Rojo-Ruiz, Jonathan
Navas-Navarro, Paloma
Nuñez, Lucía
García-Sancho, Javier
Alonso, María Teresa
Imaging of Endoplasmic Reticulum Ca(2+) in the Intact Pituitary Gland of Transgenic Mice Expressing a Low Affinity Ca(2+) Indicator
title Imaging of Endoplasmic Reticulum Ca(2+) in the Intact Pituitary Gland of Transgenic Mice Expressing a Low Affinity Ca(2+) Indicator
title_full Imaging of Endoplasmic Reticulum Ca(2+) in the Intact Pituitary Gland of Transgenic Mice Expressing a Low Affinity Ca(2+) Indicator
title_fullStr Imaging of Endoplasmic Reticulum Ca(2+) in the Intact Pituitary Gland of Transgenic Mice Expressing a Low Affinity Ca(2+) Indicator
title_full_unstemmed Imaging of Endoplasmic Reticulum Ca(2+) in the Intact Pituitary Gland of Transgenic Mice Expressing a Low Affinity Ca(2+) Indicator
title_short Imaging of Endoplasmic Reticulum Ca(2+) in the Intact Pituitary Gland of Transgenic Mice Expressing a Low Affinity Ca(2+) Indicator
title_sort imaging of endoplasmic reticulum ca(2+) in the intact pituitary gland of transgenic mice expressing a low affinity ca(2+) indicator
topic Endocrinology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7921146/
https://www.ncbi.nlm.nih.gov/pubmed/33664709
http://dx.doi.org/10.3389/fendo.2020.615777
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