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Permissive Modulation of Sphingosine-1-Phosphate-Enhanced Intracellular Calcium on BKCa Channel of Chromaffin Cells
Journal article   Open access   Peer reviewed

Permissive Modulation of Sphingosine-1-Phosphate-Enhanced Intracellular Calcium on BKCa Channel of Chromaffin Cells

Adonis Z Wu, Tzu-Lun Ohn, Ren-Jay Shei, Huei-Fang Wu, Yong-Cyuan Chen, Hsiang-Chun Lee, Dao-Fu Dai and Sheng-Nan Wu
International journal of molecular sciences, Vol.22(4), p.2175
02/01/2021
DOI: 10.3390/ijms22042175
PMID: 33671654
url
https://doi.org/10.3390/ijms22042175View
Published (Version of record) Open Access

Abstract

Sphingosine-1-phosphate (S1P), is a signaling sphingolipid which acts as a bioactive lipid mediator. We assessed whether S1P had multiplex effects in regulating the large-conductance Ca 2+ -activated K + channel (BK Ca ) in catecholamine-secreting chromaffin cells. Using multiple patch-clamp modes, Ca 2+ imaging, and computational modeling, we evaluated the effects of S1P on the Ca 2+ -activated K + currents ( I K(Ca) ) in bovine adrenal chromaffin cells and in a pheochromocytoma cell line (PC12). In outside-out patches, the open probability of BK Ca channel was reduced with a mean-closed time increment, but without a conductance change in response to a low-concentration S1P (1 µM). The intracellular Ca 2+ concentration (Ca i ) was elevated in response to a high-dose (10 µM) but not low-dose of S1P. The single-channel activity of BK Ca was also enhanced by S1P (10 µM) in the cell-attached recording of chromaffin cells. In the whole-cell voltage-clamp, a low-dose S1P (1 µM) suppressed I K(Ca) , whereas a high-dose S1P (10 µM) produced a biphasic response in the amplitude of I K(Ca) , i.e., an initial decrease followed by a sustained increase. The S1P-induced I K(Ca) enhancement was abolished by BAPTA. Current-clamp studies showed that S1P (1 µM) increased the action potential (AP) firing. Simulation data revealed that the decreased BK Ca conductance leads to increased AP firings in a modeling chromaffin cell. Over a similar dosage range, S1P (1 µM) inhibited I K(Ca) and the permissive role of S1P on the BK Ca activity was also effectively observed in the PC12 cell system. The S1P-mediated I K(Ca) stimulation may result from the elevated Ca i , whereas the inhibition of BK Ca activity by S1P appears to be direct. By the differentiated tailoring BK Ca channel function, S1P can modulate stimulus-secretion coupling in chromaffin cells.
intracellular Ca2 sphingosine-1-phosphate BKCa channel chromaffin cell

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