Orai1α and Orai1β more potently promote NFAT activation and transcription than Orai2 and Orai3
- 1University of Pittsburgh
Abstract
The Ca2+ release-activated Ca2+ (CRAC) channel mediates store-operated calcium entry (SOCE), a ubiquitous pathway essential for many cell types, including immune cells. Three Orai (Orai1, Orai2, Orai3) proteins constitute the plasma membrane pore-forming units of CRAC channels that are activated by the endoplasmic reticulum (ER) Ca2+-sensing STIM1 and STIM2 proteins when ER Ca2+ stores are depleted. Orai1/2/3 are differentially expressed across primary cells with discernible differences in their structures and biophysical properties. Further, Orai1 has two alternatively translated isoforms: the long mammalian-specific Orai1alpha and the 63-residue shorter Orai1beta, which is evolutionarily older and conserved across vertebrates. Whether Orai1alpha/1beta/2/3 at native expression levels produce unique cytosolic Ca2+ signatures that bias transcriptional responses through effectors like NFAT is unclear. Here we used HEK293 cells engineered to express one native Orai isoform and show that all Orai isoforms couple to NFAT1 and NFAT4 induction. The magnitude of NFAT1/4 induction tracked the magnitude of SOCE, with the following profile: Orai1alpha>Orai1beta>>Orai2>Orai3. Near-native ectopic expression of either Orai1alpha or Orai1beta in primary murine Orai1-/-CD4+ T cells restored SOCE, NFAT activation, cytokine production and promoted near identical transcriptional responses enriched for immune activation pathways. An analysis of genetic and clinical data of human individuals showed that homozygous null mutations selectively abolishing Orai1alphaare not associated with disease resembling CRAC channelopathy. Primary T cells from individuals homozygous or heterozygous for an Orai1alpha null mutation showed enhanced, rather than impaired, SOCE and NFAT induction. Collectively, our data indicate that Orai isoforms regulate NFAT activation and downstream transcription primarily through the magnitude of SOCE they support, with Orai1alpha and Orai1beta being the most potent isoforms coupling SOCE to NFAT responses.
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BibTeX
@misc{abdelnaby2026orai1α,
title = {{Orai1α and Orai1β more potently promote NFAT activation and transcription than Orai2 and Orai3}},
author = {A. E. Abdelnaby and Y.-H. Wang and C. J. Benson and I. P. Perez and B. Shen and M. McDermott and M. Jishage and A. T. Elhaw and S. Cruz-Rangel and R. Courjaret and A. Belkadi and F. Yu and D. Prado and S. Yuan and P. Xin and A. C. Straub and F. J. Schopfer and N. Hempel and W. Hawse and D. Beck and K. Machaca and S. Feske and M. Trebak},
howpublished = {bioRxiv},
year = {2026},
month = jul,
doi = {10.64898/2026.07.10.737753},
url = {https://www.biorxiv.org/content/10.64898/2026.07.10.737753v2},
note = {CC BY},
}
RIS
TY - UNPB
TI - Orai1α and Orai1β more potently promote NFAT activation and transcription than Orai2 and Orai3
AU - A. E. Abdelnaby
AU - Y.-H. Wang
AU - C. J. Benson
AU - I. P. Perez
AU - B. Shen
AU - M. McDermott
AU - M. Jishage
AU - A. T. Elhaw
AU - S. Cruz-Rangel
AU - R. Courjaret
AU - A. Belkadi
AU - F. Yu
AU - D. Prado
AU - S. Yuan
AU - P. Xin
AU - A. C. Straub
AU - F. J. Schopfer
AU - N. Hempel
AU - W. Hawse
AU - D. Beck
AU - K. Machaca
AU - S. Feske
AU - M. Trebak
PY - 2026
DA - 2026/07/10
PB - bioRxiv
DO - 10.64898/2026.07.10.737753
UR - https://www.biorxiv.org/content/10.64898/2026.07.10.737753v2
AB - The Ca2+ release-activated Ca2+ (CRAC) channel mediates store-operated calcium entry (SOCE), a ubiquitous pathway essential for many cell types, including immune cells. Three Orai (Orai1, Orai2, Orai3) proteins constitute the plasma membrane pore-forming units of CRAC channels that are activated by the endoplasmic reticulum (ER) Ca2+-sensing STIM1 and STIM2 proteins when ER Ca2+ stores are depleted. Orai1/2/3 are differentially expressed across primary cells with discernible differences in their structures and biophysical properties. Further, Orai1 has two alternatively translated isoforms: the long mammalian-specific Orai1alpha and the 63-residue shorter Orai1beta, which is evolutionarily older and conserved across vertebrates. Whether Orai1alpha/1beta/2/3 at native expression levels produce unique cytosolic Ca2+ signatures that bias transcriptional responses through effectors like NFAT is unclear. Here we used HEK293 cells engineered to express one native Orai isoform and show that all Orai isoforms couple to NFAT1 and NFAT4 induction. The magnitude of NFAT1/4 induction tracked the magnitude of SOCE, with the following profile: Orai1alpha>Orai1beta>>Orai2>Orai3. Near-native ectopic expression of either Orai1alpha or Orai1beta in primary murine Orai1-/-CD4+ T cells restored SOCE, NFAT activation, cytokine production and promoted near identical transcriptional responses enriched for immune activation pathways. An analysis of genetic and clinical data of human individuals showed that homozygous null mutations selectively abolishing Orai1alphaare not associated with disease resembling CRAC channelopathy. Primary T cells from individuals homozygous or heterozygous for an Orai1alpha null mutation showed enhanced, rather than impaired, SOCE and NFAT induction. Collectively, our data indicate that Orai isoforms regulate NFAT activation and downstream transcription primarily through the magnitude of SOCE they support, with Orai1alpha and Orai1beta being the most potent isoforms coupling SOCE to NFAT responses.
ER -