Notch enhances Ca 2+ entry by activating calcium-sensing receptors and inhibiting voltage-gated K + channels

• Published in: American Journal of Physiology: Cell Physiology Vol. 318; no. 5; p. C954
• Main Authors: Song, Shanshan, Babicheva, Aleksandra, Zhao, Tengteng, Ayon, Ramon J, Rodriguez, Marisela, Rahimi, Shamin, Balistrieri, Francesca, Harrington, Angela, Shyy, John Y-J, Thistlethwaite, Patricia A, Makino, Ayako, Yuan, Jason X-J
• Format: Journal Article
• Language: English
• Published: United States 01-05-2020
• Subjects: Calcium Channels - drug effects; Calcium Channels - genetics; Calcium Signaling - genetics; Endoplasmic Reticulum - genetics; Endoplasmic Reticulum - metabolism; Estrenes - pharmacology; HEK293 Cells; Humans; Indoles - pharmacology; Jagged-1 Protein - genetics; Kv1.2 Potassium Channel - genetics; Kv1.5 Potassium Channel - genetics; Membrane Potentials - drug effects; Myocytes, Smooth Muscle - metabolism; Pulmonary Arterial Hypertension - genetics; Pulmonary Arterial Hypertension - metabolism; Pulmonary Arterial Hypertension - pathology; Pulmonary Artery - metabolism; Pulmonary Artery - pathology; Pyrrolidinones - pharmacology; Receptors, Calcium-Sensing - drug effects; Receptors, Calcium-Sensing - genetics; Receptors, Notch - genetics; Single-Cell Analysis; Stromal Interaction Molecule 2 - genetics; GPCR; CaSR; KCNA5 and KCNA2; STIM2; Notch
• ISSN: 1522-1563
• DOI: 10.1152/ajpcell.00487.2019

The increase in cytosolic Ca
concentration ([Ca
]
) and upregulation of calcium-sensing receptor (CaSR) and stromal interaction molecule 2 (STIM2) along with inhibition of voltage-gated K
(K
) channels in pulmonary arterial smooth muscle cells (PASMC) have been implicated in the development of pulmonary arterial hypertension; however, the precise upstream mechanisms remain elusive. Activation of CaSR, a G protein-coupled receptor (GPCR), results in Ca
release from the endoplasmic/sarcoplasmic reticulum (ER/SR) and Ca
influx through receptor-operated and store-operated Ca
channels (SOC). Upon Ca
depletion from the SR, STIM forms clusters to mediate store-operated Ca
entry. Activity of K
channels, like KCNA5/K
1.5 and KCNA2/K
1.2, contributes to regulating membrane potential, and inhibition of K
channels results in membrane depolarization that increases [Ca
]
by opening voltage-dependent Ca
channels. In this study, we show that activation of Notch by its ligand Jag-1 promotes the clustering of STIM2, and clustered STIM2 subsequently enhances the CaSR-induced Ca
influx through SOC channels. Extracellular Ca
-mediated activation of CaSR increases [Ca
]
in
-transfected HEK293 cells. Treatment of
-transfected cells with Jag-1 further enhances CaSR-mediated increase in [Ca
]
. Moreover, CaSR-mediated increase in [Ca
]
was significantly augmented in cells co-transfected with
and
. CaSR activation results in STIM2 clustering in
-cotransfected cells. Notch activation also induces significant clustering of STIM2. Furthermore, activation of Notch attenuates whole cell K
currents in
- and
-transfected cells. Together, these results suggest that Notch activation enhances CaSR-mediated increases in [Ca
]
by enhancing store-operated Ca
entry and inhibits KCNA5/K
1.5 and KCNA2/K
1.2, ultimately leading to voltage-activated Ca
entry.