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Cross-talk between N-terminal and C-terminal domains in stromal interaction molecule 2 (STIM2) determines enhanced STIM2 sensitivity.
J Biol Chem. 2019 04 19; 294(16):6318-6332.JB

Abstract

Store-operated Ca2+ entry (SOCE) is a ubiquitous pathway for Ca2+ influx across the plasma membrane (PM). SOCE is mediated by the endoplasmic reticulum (ER)-associated Ca2+-sensing proteins stromal interaction molecule 1 (STIM1) and STIM2, which transition into an active conformation in response to ER Ca2+ store depletion, thereby interacting with and gating PM-associated ORAI1 channels. Although structurally homologous, STIM1 and STIM2 generate distinct Ca2+ signatures in response to varying strengths of agonist stimulation. The physiological functions of these Ca2+ signatures, particularly under native conditions, remain unclear. To investigate the structural properties distinguishing STIM1 and STIM2 activation of ORAI1 channels under native conditions, here we used CRISPR/Cas9 to generate STIM1-/-, STIM2-/-, and STIM1/2-/- knockouts in HEK293 and colorectal HCT116 cells. We show that depending on cell type, STIM2 can significantly sustain SOCE in response to maximal store depletion. Utilizing the SOCE modifier 2-aminoethoxydiphenyl borate (2-APB), we demonstrate that 2-APB-activated store-independent Ca2+ entry is mediated exclusively by endogenous STIM2. Using variants that either stabilize or disrupt intramolecular interactions of STIM C termini, we show that the increased flexibility of the STIM2 C terminus contributes to its selective store-independent activation by 2-APB. However, STIM1 variants with enhanced flexibility in the C terminus failed to support its store-independent activation. STIM1/STIM2 chimeric constructs indicated that coordination between N-terminal sensitivity and C-terminal flexibility is required for specific store-independent STIM2 activation. Our results clarify the structural determinants underlying activation of specific STIM isoforms, insights that are potentially useful for isoform-selective drug targeting.

Authors+Show Affiliations

From the Departments of Cellular and Molecular Physiology and.From the Departments of Cellular and Molecular Physiology and.From the Departments of Cellular and Molecular Physiology and.From the Departments of Cellular and Molecular Physiology and.From the Departments of Cellular and Molecular Physiology and.From the Departments of Cellular and Molecular Physiology and.From the Departments of Cellular and Molecular Physiology and.the Secretory Physiology Section, NIDCR, National Institutes of Health, Bethesda, Maryland 20892, and.From the Departments of Cellular and Molecular Physiology and.the Secretory Physiology Section, NIDCR, National Institutes of Health, Bethesda, Maryland 20892, and.Pharmacology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033.the Department of Physiology and Biophysics, Weill Cornell Medical College in Qatar, Education City, Qatar Foundation, P.O. Box 24144, Doha, Qatar.From the Departments of Cellular and Molecular Physiology and.From the Departments of Cellular and Molecular Physiology and mtrebak@psu.edu.

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

30824535

Citation

Emrich, Scott M., et al. "Cross-talk Between N-terminal and C-terminal Domains in Stromal Interaction Molecule 2 (STIM2) Determines Enhanced STIM2 Sensitivity." The Journal of Biological Chemistry, vol. 294, no. 16, 2019, pp. 6318-6332.
Emrich SM, Yoast RE, Xin P, et al. Cross-talk between N-terminal and C-terminal domains in stromal interaction molecule 2 (STIM2) determines enhanced STIM2 sensitivity. J Biol Chem. 2019;294(16):6318-6332.
Emrich, S. M., Yoast, R. E., Xin, P., Zhang, X., Pathak, T., Nwokonko, R., Gueguinou, M. F., Subedi, K. P., Zhou, Y., Ambudkar, I. S., Hempel, N., Machaca, K., Gill, D. L., & Trebak, M. (2019). Cross-talk between N-terminal and C-terminal domains in stromal interaction molecule 2 (STIM2) determines enhanced STIM2 sensitivity. The Journal of Biological Chemistry, 294(16), 6318-6332. https://doi.org/10.1074/jbc.RA118.006801
Emrich SM, et al. Cross-talk Between N-terminal and C-terminal Domains in Stromal Interaction Molecule 2 (STIM2) Determines Enhanced STIM2 Sensitivity. J Biol Chem. 2019 04 19;294(16):6318-6332. PubMed PMID: 30824535.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Cross-talk between N-terminal and C-terminal domains in stromal interaction molecule 2 (STIM2) determines enhanced STIM2 sensitivity. AU - Emrich,Scott M, AU - Yoast,Ryan E, AU - Xin,Ping, AU - Zhang,Xuexin, AU - Pathak,Trayambak, AU - Nwokonko,Robert, AU - Gueguinou,Maxime F, AU - Subedi,Krishna P, AU - Zhou,Yandong, AU - Ambudkar,Indu S, AU - Hempel,Nadine, AU - Machaca,Khaled, AU - Gill,Donald L, AU - Trebak,Mohamed, Y1 - 2019/03/01/ PY - 2018/12/17/received PY - 2019/02/28/revised PY - 2020/04/19/pmc-release PY - 2019/3/3/pubmed PY - 2019/10/17/medline PY - 2019/3/3/entrez KW - Calcium signaling KW - Ion sensor KW - SOCE KW - STIM2 KW - calcium channel KW - calcium imaging KW - calcium intracellular release KW - calcium release-activated calcium channel protein 1 (ORAI1) KW - calcium transport KW - cation channel KW - stromal interaction molecule 1 (STIM1) SP - 6318 EP - 6332 JF - The Journal of biological chemistry JO - J. Biol. Chem. VL - 294 IS - 16 N2 - Store-operated Ca2+ entry (SOCE) is a ubiquitous pathway for Ca2+ influx across the plasma membrane (PM). SOCE is mediated by the endoplasmic reticulum (ER)-associated Ca2+-sensing proteins stromal interaction molecule 1 (STIM1) and STIM2, which transition into an active conformation in response to ER Ca2+ store depletion, thereby interacting with and gating PM-associated ORAI1 channels. Although structurally homologous, STIM1 and STIM2 generate distinct Ca2+ signatures in response to varying strengths of agonist stimulation. The physiological functions of these Ca2+ signatures, particularly under native conditions, remain unclear. To investigate the structural properties distinguishing STIM1 and STIM2 activation of ORAI1 channels under native conditions, here we used CRISPR/Cas9 to generate STIM1-/-, STIM2-/-, and STIM1/2-/- knockouts in HEK293 and colorectal HCT116 cells. We show that depending on cell type, STIM2 can significantly sustain SOCE in response to maximal store depletion. Utilizing the SOCE modifier 2-aminoethoxydiphenyl borate (2-APB), we demonstrate that 2-APB-activated store-independent Ca2+ entry is mediated exclusively by endogenous STIM2. Using variants that either stabilize or disrupt intramolecular interactions of STIM C termini, we show that the increased flexibility of the STIM2 C terminus contributes to its selective store-independent activation by 2-APB. However, STIM1 variants with enhanced flexibility in the C terminus failed to support its store-independent activation. STIM1/STIM2 chimeric constructs indicated that coordination between N-terminal sensitivity and C-terminal flexibility is required for specific store-independent STIM2 activation. Our results clarify the structural determinants underlying activation of specific STIM isoforms, insights that are potentially useful for isoform-selective drug targeting. SN - 1083-351X UR - https://www.unboundmedicine.com/medline/citation/30824535/Cross_talk_between_N_terminal_and_C_terminal_domains_in_stromal_interaction_molecule_2__STIM2__determines_enhanced_STIM2_sensitivity_ L2 - http://www.jbc.org/cgi/pmidlookup?view=long&pmid=30824535 DB - PRIME DP - Unbound Medicine ER -