Dataset Information

Cytosolic Ca²⁺ Modulates Golgi Structure Through PKC?-Mediated GRASP55 Phosphorylation.

ABSTRACT: It has been well documented that the ER responds to cellular stresses through the unfolded protein response (UPR), but it is unknown how the Golgi responds to similar stresses. In this study, we treated HeLa cells with ER stress inducers, thapsigargin (TG), tunicamycin (Tm), and dithiothreitol (DTT), and found that only TG treatment resulted in Golgi fragmentation. TG induced Golgi fragmentation at a low dose and short time when UPR was undetectable, indicating that Golgi fragmentation occurs independently of ER stress. Further experiments demonstrated that TG induces Golgi fragmentation through elevating intracellular Ca²⁺ and protein kinase C? (PKC?) activity, which phosphorylates the Golgi stacking protein GRASP55. Significantly, activation of PKC? with other activating or inflammatory agents, including phorbol 12-myristate 13-acetate and histamine, modulates Golgi structure in a similar fashion. Hence, our study revealed a novel mechanism through which increased cytosolic Ca²⁺ modulates Golgi structure and function.

SUBMITTER: Ireland S

PROVIDER: S-EPMC7078314 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

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Cytosolic Ca<sup>2+</sup> Modulates Golgi Structure Through PKCα-Mediated GRASP55 Phosphorylation.

Ireland Stephen S Ramnarayanan Saiprasad S Fu Mingzhou M Zhang Xiaoyan X Zhang Jianchao J Li Jie J Emebo Dabel D Wang Yanzhuang Y

iScience 20200228 3

It has been well documented that the ER responds to cellular stresses through the unfolded protein response (UPR), but it is unknown how the Golgi responds to similar stresses. In this study, we treated HeLa cells with ER stress inducers, thapsigargin (TG), tunicamycin (Tm), and dithiothreitol (DTT), and found that only TG treatment resulted in Golgi fragmentation. TG induced Golgi fragmentation at a low dose and short time when UPR was undetectable, indicating that Golgi fragmentation occurs in ...[more]

PMID: 32179476

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Project description:Mucociliary clearance is a pivotal physiological mechanism that protects the lung by cleaning the airways from pollution and colonization, thereby preventing infection. Ciliary function is influenced by various signal transduction cascades, and Ca2+ represents a key second messenger. A fixed 20:1 combination of cafedrine and theodrenaline has been widely used to treat perioperative hypotension and emergency hypotensive states since the 1960s; however, its effect on the intracellular Ca2+ concentration ([Ca2+]i) of respiratory epithelium remains unknown. Therefore, human tracheal epithelial cells were exposed to the clinically applied 20:1 mixture of cafedrine/theodrenaline and the individual substances separately. [Ca2+]i was assessed by FURA-2 340/380 fluorescence ratio. Pharmacological inhibitors were applied to elucidate relevant signal transduction cascades, and reverse transcription polymerase chain reaction (RT-PCR) was performed on murine tracheal epithelium to analyze ryanodine receptor (RyR) subtype expression. All three pharmacological preparations instantaneously induced a steep increase in [Ca2+]i that quickly returned to its baseline value despite the persistence of each substance. Peak [Ca2+]i following the administration of 20:1 cafedrine/theodrenaline, cafedrine alone, and theodrenaline alone increased in a dose-dependent manner, with median effective concentrations of 0.35 mM (7.32 mM cafedrine and 0.35 mM theodrenaline), 3.14 mM, and 3.45 mM, respectively. When extracellular Ca2+ influx was inhibited using a Ca2+-free buffer solution, the peak [Ca2+]i following the administration of cafedrine alone and theodrenaline alone were reduced but not abolished. No alteration in [Ca2+]i compared with baseline [Ca2+]i was observed during β-adrenergic receptor inhibition. Depletion of caffeine-sensitive stores and inhibition of RyR, but not IP3 receptors, completely abolished any increase in [Ca2+]i. However, [Ca2+]i still increased following the depletion of mitochondrial Ca2+ stores using 2,4-dinitrophenol. RT-PCR revealed RyR-2 and RyR-3 expression on murine tracheal epithelium. Although our experiments showed that cafedrine/theodrenaline, cafedrine alone, or theodrenaline alone release Ca2+ from intracellular stores through mechanisms that are exclusively triggered by β-adrenergic receptor stimulation, which most probably lead to RyR activation, clinical plasma concentrations are considerably lower than those used in our experiments to elicit an increase in [Ca2+]i; therefore, further studies are needed to evaluate the ability of cafedrine/theodrenaline to alter mucociliary clearance in clinical practice.

Dataset Information

Cytosolic Ca²⁺ Modulates Golgi Structure Through PKC?-Mediated GRASP55 Phosphorylation.

Publications

Cytosolic Ca<sup>2+</sup> Modulates Golgi Structure Through PKCα-Mediated GRASP55 Phosphorylation.

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Dataset Information

Cytosolic Ca2+ Modulates Golgi Structure Through PKC?-Mediated GRASP55 Phosphorylation.

Publications

Cytosolic Ca<sup>2+</sup> Modulates Golgi Structure Through PKCα-Mediated GRASP55 Phosphorylation.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Cytosolic Ca²⁺ Modulates Golgi Structure Through PKC?-Mediated GRASP55 Phosphorylation.