Calcium entry for lymphocyte chemotaxis: the compartment discriminates more than the channel

Question: How do distinct plasma membrane calcium entry pathways, such as TRPC channels or calcium release-activated channel regulators, contribute to chemokine-induced migration of lymphocytes independently of store-operated calcium entry?

Answer

Across the retrieved papers, the answer that survives is narrower than the question's framing: SOCE-independence in chemokine-driven lymphocyte migration is currently documented for the same CRAC machinery redeployed at the plasma membrane, not for a parallel TRPC-type entry route. A plasma-membrane pool of STIM1 drives constitutive calcium entry and is required for CXCL12/CXCR4-induced B cell migration independently of store-operated entry, whereas the ER pool of STIM1 and Orai1 are required within the store-operated arm [2]. Layered on this, ORAI/CRAC components demonstrably carry functions that are uncoupled from store depletion — STIM-independent priming of Orai1 assembly [3] and calcium-conduction-independent, scaffold-like activity of an Orai isoform [11] — which is the mechanistically plausible route by which a "CRAC regulator" could shape motility without being SOCE. No retrieved paper tests TRPC channels in lymphocyte chemokine sensing or trafficking, so any claim that TRPC channels provide the SOCE-independent pathway remains unsupported here.

A plasma-membrane STIM1 pool, not a second channel, is the documented SOCE-independent calcium route in lymphocyte chemotaxis

STIM1 exists at the plasma membrane in two orientations in addition to its ER pool, and this pool contributes constitutive calcium entry (CCE) [2]. Both STIM1ER and Orai1 are required for CXCL12-induced B cell migration, yet STIM1PM actively regulates migration independently of SOCE, controls CCE, and modulates intercellular interactions that feed into chemotactic responses [2]. Targeting STIM1PM domains significantly impairs B cell migration, which is the strongest causal evidence in this corpus that a non-store-operated, plasma-membrane calcium entry route is rate-limiting for a chemokine response rather than merely correlating with it [2]. The authors themselves describe the output as spanning calcium-dependent and calcium-independent mechanisms, so the flux-dependence of the migration defect is not settled [2].

Orai1 is required for chemokine-induced migration, but that requirement cannot be assigned to a SOCE-independent pore function

Because Orai1 is required for CXCL12-induced B cell migration in the same setting in which STIM1ER is required, the Orai1 dependence is compatible with conventional store-operated gating rather than with a separate activation mode [2]. Interpreting Orai1 loss-of-function as channel-specific is further complicated by graded coupling among the Orai quartet: all native Orai isoforms couple to NFAT1/4 induction in proportion to the SOCE they support (Orai1β > Orai1 >> Orai2 > Orai3) [8]. Primary T cells from individuals homozygous or heterozygous for an Orai1 null mutation showed enhanced, rather than impaired, SOCE and NFAT induction, and homozygous Orai1 null mutations were not associated with a CRAC-channelopathy-like disease [8]. Compensation therefore makes Orai1-dependence an unreliable readout of a distinct, non-SOCE calcium entry pathway in lymphocytes [8].

CRAC-channel regulators can gate Orai1 without store depletion, which is the cleanest precedent for SOCE-independent CRAC function

Syntaxin11 binds Orai1 directly and primes it for on-site multimeric assembly in a STIM-independent step that is nevertheless required for gating; Syntaxin11 depletion inhibits SOCE, CRAC currents, NFAT activation and degranulation in patient T lymphocytes and cell lines without affecting membrane trafficking [3]. This establishes that the CRAC channel's activation state can be set by a regulator distinct from the ER calcium sensor, which is the mechanistic class of event that could dissociate CRAC-dependent motility from store depletion [3]. A second layer of regulation sits upstream of STIM1 itself: DHHC21 is required for STIM1 S-acylation and for SOCE in vitro and in vivo, and is recruited into Orai1/STIM1 puncta upon store depletion [9]. Neither study measures migration, so the motility consequence of these regulators remains inferred rather than shown [3] [9].

Orai proteins have functions separable from both SOCE and ion conduction, making "channel identity" the wrong unit of analysis

In primary human muscle stem cells, Orai3 promotes activation in a calcium-independent manner and does not contribute to SOCE or to serum-induced calcium responses, arguing that an Orai protein can act through a non-conductive, possibly scaffold function [11]. In the same study Orai3 partners with the large scaffold AHNAK2, and the two act through different signalling pathways on the same activation decision [11]. Orai1 also has a plasma-membrane-integrity role outside the immune setting, being required together with EHD2 for repair of mechanically induced plasma membrane lesions, mechanosensitive YAP/TAZ-TEAD activation and mechanoadaptation [13]. Such non-SOCE, membrane-proximal Orai functions are plausible contributors to migration through confined or mechanically loaded environments, but none of these studies was performed in lymphocytes [11] [13].

What gates chemokine-directed motility is the spatial and temporal geometry of the calcium signal, not the entry channel per se

In neutrophils, PLCγ2 is required for spontaneous calcium oscillations and for the chemoattractant-induced calcium response, and its loss changes membrane targeting of the RasGAP CAPRI, Ras/PI3Kγ/actin activation, and the chemoattractant concentration range over which chemotaxis occurs [12]. This places the encoding step — oscillation competence and downstream Ras tuning — upstream of any particular plasma membrane entry route, though the measurements are in neutrophils rather than lymphocytes [12]. Compartmentalisation similarly dominates chemokine receptor signalling: endosomal CCR7 uniquely enriches Rho GTPase regulators relative to plasma membrane CCR7, and this correlates with enhanced Rac1 activity and T cell chemotaxis [4]. At the ER–plasma membrane interface the control loop is likewise cortical and partially autonomous: STIM1 oscillations share periodicity with calcium oscillations but can occur independently of them, and persistent ER–PM contact sites reduce oscillation amplitude without changing frequency [10].

Pharmacological CRAC blockade changes chemokine output more convincingly than it changes chemokine sensing

The CRAC channel inhibitor Auxora reduced plasma CCL8 and PDGF-AA in patients with severe SARS-CoV-2 pneumonia, and Auxora acted directly on T cells to inhibit CCL8 and PDGFA transcription in monocyte-derived macrophages [6]. That is an effect on chemokine production within an inflammatory circuit, not on a lymphocyte's ability to migrate to a chemokine gradient [6]. Single-cell profiling of SOCE blockade shows the same selectivity logic: BTP2 and CM4620 reduced cytotoxicity-associated genes in CD8 effector T cells and NK cells while preserving activation-induced anti-inflammatory programs in CD4 regulatory T cells [14]. These results constrain how a SOCE-independent entry pathway should be defined functionally — as a motility-specific route, not as the target of available CRAC inhibitors [14].

Conflicts and gaps

The central tension is internal to the strongest paper: STIM1PM is said to regulate migration independently of SOCE, yet Orai1 is required for the same CXCL12 response, leaving the conducting pore for CCE unidentified [2]. "Independent of SOCE" there denotes independence from store-operated activation, not independence from Orai1, and the two are routinely conflated. The PLCγ2 neutrophil study is also difficult to read directionally: its abstract concludes that PLCγ2 loss makes neutrophils respond at a "subsensitive chemoattraction," while its highlights describe increased sensitivity and activation of GPCR-mediated signalling pathways [12]. Most consequentially, this corpus contains no experiment on TRPC channels in lymphocyte chemokine sensing, adhesion under flow, or trafficking; TRPC work retrieved here concerns tumour cells and endothelium [1] [15], and the one lymphoma-relevant mechanosensitive entry study concerns muscle stem cells [5]. The claim that TRPC channels supply a SOCE-independent lymphocyte calcium entry pathway is therefore untested rather than refuted in this literature.

What would change the answer

A separation-of-function design is needed: plasma-membrane-restricted versus ER-restricted STIM1 mutants that cannot gate Orai1, expressed in primary T and B cells, scored in CXCL12/CCL19 gradients in transwell and 3D collagen assays with simultaneous TIRF calcium imaging and Rac1/Cdc42 biosensors [2]. Isoform-resolved reconstitution of Orai1-null primary T cells with Orai1 versus Orai1β would test whether the migration-relevant conductance is carried by a specific pore stoichiometry rather than by total SOCE [8]. Tether-based optical single-channel recording, which has resolved unitary calcium transport from low-conductance channels in intact membrane, could identify the channel underlying CCE directly [7]. Finally, conditional TRPC deletion in T cells combined with intravital lymph node imaging and shear-flow adhesion assays would either populate or close the TRPC gap that this corpus leaves open [2].

References

[1] jinhui, z., Guo, x., liao, w., wu, p., Wu, Y., Guo, Y. g., gao, l.. "TRPC6 channel inhibition disturbs store-operated Ca2+ entry to delay proliferation in bladder cancer". bioRxiv. 2026-01-30T00:00:00.000Z. URL: https://doi.org/10.64898/2026.01.29.702689

[2] LE GOUX, N., Buscaglia, P., Mainguy, A., Hus, M., Blery, M., Mignen, O.. "STIM1 at the plasma membrane: A novel Molecular regulator of B cell migration.". bioRxiv. 2026-10-19T00:00:00.000Z. URL: https://doi.org/10.64898/2026.10.14.759286

[3] Datta, S., Gupta, A., Jagetiya, K. M., Bera, R., Tiwari, V. R., Yamashita, M., Yande, A. R., Rishad, A., Malik, V., Raran-Kurussi, S., Ammann, S., Shahrooei, M., Mandal, K., Sowdhamini, R., Prakriya, M., Dani, A., Vig, M.. "Syntaxin11 Deficiency Inhibits CRAC Channel Priming to Suppress Cytotoxicity and Gene Expression in T Lymphocytes Independent of Membrane Trafficking.". bioRxiv. 2026-08-04T00:00:00.000Z. URL: https://doi.org/10.1101/2024.10.25.620144

[4] Hahn, H., Daly, C., Little, J., Perry-Hauser, N. A., Flores-Espinoza, E., Inoue, A., Plouffe, B., Thomsen, A. R. B.. "Endosomal Chemokine Receptor Signalosomes Regulate Central Mechanisms Underlying Cell Migration". bioRxiv. 2024-12-02T00:00:00.000Z. URL: https://doi.org/10.1101/2022.09.27.509755

[5] Hirano, K., Ishikawa, Y., Motohashi, N., Kobata, Y., Watanabe, H., Sasaki, M., Yokoyama, T., Yamada, Y., Aoyagi, Y., Takakura, K., Murakami, A., Tsuchiya, M., Ono, Y., Nonomura, K., Aoki, Y., Hara, Y.. "Biomechanical regulation of Ca2+ dynamics during muscle stem cell activation". bioRxiv. 2026-08-28T00:00:00.000Z. URL: https://doi.org/10.64898/2026.05.19.726396

[6] Casalino-Matsuda, S. M., Guggilla, V., Gao, C. A., Demeulenaere, K. E., Cusick, L. P., Fenske, S. W., Yu, Z., Lu, Z., Swaminathan, S., Grant, R. A., Schleck, M. J., Prakriya, M., Hebbar, S., Stauderman, K., Donnelly, H. K., Pickens, C., Morales-Nebreda, L., The NU SCRIPT Study Investigators,, Wunderink, R. G., Misharin, A. V., Singer, B. D., Budinger, G. S.. "The CRAC channel inhibitor Auxora interrupts inflammatory circuits between alveolar macrophages and T cells in patients with viral pneumonia". medRxiv. 2026-05-30T00:00:00.000Z. URL: https://doi.org/10.64898/2026.05.27.26354034

[7] Howell, M. R., Cohen, A. E.. "Optical single-channel recording via diffusional confinement in membrane tethers". bioRxiv. 2025-05-09T00:00:00.000Z. URL: https://doi.org/10.1101/2025.05.07.652649

[8] Abdelnaby, A. E., Wang, Y.-H., Benson, C. J., Perez, I. P., Shen, M., McDermott, M., Jishage, M., Elhaw, A. T., Cruz-Rangel, S., Courjaret, R., Belkadi, A., Yu, F., Prado, D., Yuan, S., Xin, P., Straub, A. C., Schopfer, F. F., Hempel, N., Hawse, W., Beck, D., Machaca, K., Feske, S., Trebak, M.. "A Quartet of Native Orai Channel Isoforms Orchestrates Graded NFAT Activation and Transcription". bioRxiv. 2026-07-13T00:00:00.000Z. URL: https://doi.org/10.64898/2026.07.10.737753

[9] Kodakandla, G., Fan, Y., Zhu, M. X., West, S. J., Akimzhanov, A. M., Boehning, D.. "DHHC21 is a STIM1 protein S-acyltransferase that modulates immune function in vivo". bioRxiv. 2025-10-22T00:00:00.000Z. URL: https://doi.org/10.1101/2025.10.09.681383

[10] Xiong, D., Tong, C. S., Yang, Y., Yong, J., Wu, M.. "STIM1 and Endoplasmic Reticulum-Plasma Membrane Contact Sites Oscillate Independently of Calcium-Induced Calcium Release". bioRxiv. 2025-03-17T00:00:00.000Z. URL: https://doi.org/10.1101/2025.03.16.643575

[11] Tollance, A., Fourgeaud, M., Koenig, S., Frieden, M.. "The Orai3 channel and AHNAK2 scaffold protein promote the activation of primary human muscle stem cells in vitro". bioRxiv. 2026-09-24T00:00:00.000Z. URL: https://doi.org/10.64898/2026.09.23.753807

[12] xu, x., Lee, A., jin, t., kim, w. s.. "PLCg2 Controls Neutrophil Sensitivity through Calcium Oscillation and Gates Chemoattractant Concentration Range for Chemotaxis". bioRxiv. 2025-04-08T00:00:00.000Z. URL: https://doi.org/10.1101/2025.04.07.647573

[13] Luan, H., Cerci, A., Bielecki, T. A., Mohapatra, B. C., Shrestha, S., Wu, Y., Storck, M. D., Smith, L. M., Stauderman, K. A., Coulter, D. W., Kotwal, A., Dong, J., Lim, J. Y., Band, V., Ramanathan, S. P., Band, H.. "Orai1 is required for Ca2+-dependent plasma membrane repair and mechanoadaptation". bioRxiv. 2026-05-15T00:00:00.000Z. URL: https://doi.org/10.64898/2026.05.13.724989

[14] Stephanou, A., Mantri, M., Shankaranarayanan, D., Li, C., Lagman, M., Xiang, J. Z., Pan, C., Sun, Y., Muthukumar, T., Machaca, K., de vlaminck, i., Suthanthiran, M.. "Single-cell transcriptomics reveals targeted modulation of inflammatory repertoire by SOCE blockers". bioRxiv. 2025-05-01T00:00:00.000Z. URL: https://doi.org/10.1101/2025.04.28.651042

[15] Anwar, M., Raghunathrao, V. A. B., Amin, R., Vellingiri, V., Joshi, J. C., Akhter, M. Z., Tauseef, M., El-Erian, I. H., Khaki, N., Fancher, I. S., Abdelkarim, H., Levitan, I., Chronis, K., Gaponenko, V., Mehta, D.. "A Single Mutation in TRPC6 Protects Mice from Acute Lung Injury by Regenerating Endothelium". bioRxiv. 2025-02-20T00:00:00.000Z. URL: https://doi.org/10.1101/2025.02.19.639142

How this survey was made

This survey answers one question: “How do distinct plasma membrane calcium entry pathways, such as TRPC channels or calcium release-activated channel regulators, contribute to chemokine-induced migration of lymphocytes independently of store-operated calcium entry?”

We keep our own collection of recent preprints and refresh it every day from bioRxiv, medRxiv, arXiv, PsyArXiv, SocArXiv and ChemRxiv. For each survey, we search that collection for recent work and keep the strongest matches: papers that use the same terms as the question, and papers on the same topic in different words.

The text was written from the titles and abstracts of those papers; the full texts were not read. Statements that draw on a particular paper are marked with a number in brackets. The reference list just above is the 15 papers whose work this text draws on, chosen from the 107 papers those searches returned; the rest of the shortlist is not printed. It is not a complete review of everything published on the question.

Treat this as a starting point and a reading list, not a peer-reviewed review. The searches behind this survey ran on October 22, 2026 and covered work from the previous two years.