Cell volume controlled by LRRC8A-formed volume-regulated anion channels fine-tunes T cell activation and function
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ABSTRACT:
PROVIDER: PRJNA1018950 | ENA |
REPOSITORIES: ENA
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Project description:To become fully functional effector T cells, naïve T cells undergo a drastic metabolic status shift from quiescence to substantial biosynthesis. The synthesis of biomass initiated by T cell receptor (TCR) signals drives the cell volume increase during T cell activation (T lymphoblast), which resembles the slowest extreme of hypotonic cell swelling. However, the fundamental role of cell volume regulation in TCR signaling during T lymphoblast and its underlying mechanisms remain a long-standing enigma. Here we show that optimal T cell activation and function require appropriate cell volume regulation by regulated volume decrease (RVD) mediated via volume-regulated anion channels (VRACs) during T cell blast. Pharmacological blockade of VRACs and genetic deletion of LRRC8A in T cells, the essential component of VRACs, impair T cell activation and function, particularly under weak TCR stimulation, such as low-affinity TCR-pMHC engagement and unsaturated anti-CD3e crosslinking. Additionally, LRRC8A has distinct influences on mRNA transcriptional profiles driven by various TCR signal strengths, revealing the prominent effects of cell volume regulation for T cell functions. More importantly, LRRC8A-deficient mice have defective antiviral immunity and obstacles in effector-memory transition of CD8+ T cells. Furthermore, LRRC8A escorts the thymic selection of T cells and shapes the T cell repertoire in the thymus. Mechanistically, LRRC8A governs stringent cell volume increase via RVD during T cell blast induced by activation-driven intracellular osmolytes accumulation to keep the proximal TCR signaling molecules at adequate density. T cell blast driven by TCR signal feedbacks to control T cell activation. Together, our results reveal a previously unappreciated layer of T cell activation regulation that LRRC8A acts as a cell volume controlling "valve" to facilitate T cell activation and function
2023-09-23 | GSE243574 | GEO
Project description:Volume-regulated anion channels participate in the cellular response to osmotic swelling. These membrane proteins are heteromers of LRRC8 family members whose composition determines permeation properties. Although structures of the obligatory LRRC8A subunit have previously defined the architecture of VRACs, the organization of heteromeric channels has remained elusive. Here we have closed this gap by the structural characterization of channels consisting of LRRC8A and C. Like homomeric LRRC8A, these proteins assemble as hexamers. Despite the twelve possible arrangements, we find a single predominant species with an A/C ratio of two. In this assembly, the four LRRCA subunits cluster in their preferred conformation observed in homomers as pairs of closely interacting proteins that stabilize a closed state of the channel. In contrast, the two interacting LRRC8C-subunits show a larger flexibility, underlining their role in the destabilization of the tightly packed A subunits, thereby enhancing the activation properties of the protein.
2023-01-03 | PXD035350 | Pride
Project description:Members of the leucine-rich repeat-containing 8 (LRRC8) protein family, composed of the five LRRC8A-E isoforms, are pore-forming components of the volume-regulated anion channel (VRAC), which is activated by cell swelling and transports halide anions and small organic compounds. Despite the recent availability of the cryo-EM structures of homo-hexameric LRRC8A, the structural basis of how LRRC8 isoforms other than LRRC8A contribute to the functional diversity of VRAC has remained elusive. In this study, we confirmed the absence of LRRC8 isoforms in the purified HsLRRC8D using mass spectrometry, and the structure of the HsLRRC8D homomer was analyzed using the cryo-EM. This work provides structural insights into the functional diversity of the LRRC8 protein family.
2020-05-27 | PXD018780 | Pride
Project description:Biosynthesis drives the cell volume increase during T cell activation. However, the contribution of cell volume regulation in TCR signaling during T lymphoblast formation and its underlying mechanisms remain unclear. Here we show that cell volume regulation is required for optimal T cell activation. Inhibition of VRACs (volume-regulated anion channels) and deletion of leucine-rich repeat-containing protein 8A (LRRC8A) channel components impair T cell activation and function, particularly under weak TCR stimulation. Additionally, LRRC8A has distinct influences on mRNA transcriptional profiles, indicating the prominent effects of cell volume regulation for T cell functions. Moreover, cell volume regulation via LRRC8A controls T cell-mediated antiviral immunity and shapes the TCR repertoire in the thymus. Mechanistically, LRRC8A governs stringent cell volume increase via regulated volume decrease (RVD) during T cell blast formation to keep the TCR signaling molecules at an adequate density. Together, our results show a further layer of T cell activation regulation that LRRC8A functions as a cell volume controlling "valve" to facilitate T cell activation.
| S-EPMC10625614 | biostudies-literature
Project description:Deficient LRRC8A-dependent Volume-Regulated Anion Channel (VRAC) activity is associated with male infertility in mouse and humans
| PRJNA448855 | ENA
Project description:DNA sensing is a fundamental process in the immune system, including host defence against viruses. The DNA sensor cGAS synthesises 2’3’ cyclic GMP-AMP (cGAMP), a second messenger that activates STING, which subsequently induces innate immunity. cGAMP not only activates STING in the cell where it is produced but also transfers to other cells. Transporters, channels and pores including SLC19A1, the SLC46A family, P2X7, ABCC1 and volume-regulated anion channels (VRACs) release cGAMP into the extracellular space and/or import cGAMP into cells. Emerging evidence suggests these proteins are important in antiviral immunity. Here, we investigated whether viruses antagonise cGAMP transporters, channels and pores. We report that infection with multiple human viruses depleted cGAMP conduits from cells. This included herpes simplex virus 1 (HSV-1) that targeted the VRAC subunits LRRC8A and LRRC8C, as well as SLC46A2 and P2X7, for degradation. The HSV-1 protein UL56 was required and sufficient for these effects that were mediated at least partially by proteasomal turnover. UL56 thereby inhibited the cGAMP uptake via VRAC, SLC46A2 and P2X7. Taken together, we show that HSV-1 actively antagonises cGAMP transfer across the plasma membrane and propose this limits innate immunity by reducing cell-to-cell communication via the immunotransmitter cGAMP.
2024-04-15 | PXD043229 | Pride
Project description:Regulation of cell volume is essential for tissue homeostasis and cell viability. In response to hypertonic stress, cells need rapid electrolyte influx to compensate water loss and to prevent cell death in a process known as regulatory volume increase (RVI). However, the molecular component able to trigger such process was unknown to date. Using a genome wide CRISPR/Cas9 screen, we identified LRRC8A, which encodes a chloride channel subunit, as the gene most associated with cell survival under hypertonic conditions. Hypertonicity activates the p38 stress-activated protein kinase pathway and its downstream MSK1 kinase, which phosphorylates and activates LRRC8A. LRRC8A-mediated Cl efflux facilitates activation of the with-no-lysine (WNK) kinase pathway, which in turn, promotes electrolyte influx via Na+ /K+ /2Cl cotransporter (NKCC) and RVI under hypertonic stress. LRRC8A-S217A mutation impairs channel activation by MSK1, resulting in reduced RVI and cell survival. In summary, LRRC8A is key to bidirectional osmotic stress responses and cell survival under hypertonic conditions.
2021-05-29 | GSE158316 | GEO
Project description:We reported the essential function of Lrrc8a on germline development
2020-05-01 | GSE112730 | GEO
Project description:Volume-regulated anion channels (VRACs) are key players in regulatory volume decrease of vertebrate cells by mediating the extrusion of chloride and organic osmolytes. They play additional roles in various physiological processes beyond their role in osmotic volume regulation. VRACs are formed by heteromers of LRRC8 proteins; LRRC8A (also called SWELL1) is an essential subunit that combines with any of its paralogs, LRRC8B-E, to form hexameric VRAC complexes. The subunit composition of VRACs determines electrophysiological characteristics of their anion transport such as single-channel conductance, outward rectification, and depolarization-dependent inactivation kinetics. In addition, differently composed VRACs conduct diverse substrates, such as LRRC8D enhancing VRAC permeability to organic substances like taurine or cisplatin. Here, after a recapitulation of the biophysical properties of VRAC-mediated ion and osmolyte transport, we summarize the insights gathered since the molecular identification of VRACs. We describe the recently solved structures of LRRC8 complexes and discuss them in terms of their structure-function relationships. These studies open up many potential avenues for future research.
| S-EPMC6451053 | biostudies-literature
Project description:The volume-regulated anion channel (VRAC) is a hexameric complex formed by LRRC8 proteins. VRACs are responsible for the regulatory volume decrease (RVD) after hypotonic cell swelling by mediating the efflux of chloride. Besides chloride, LRRC8 proteins transport other molecules including immunomodulatory cyclic dinucleotides (CDNs) such as 2’3’cGAMP. Here we identify LRRC8C as a critical component of VRACs in T cells, where its deletion abolishes VRAC currents and RVD. We find that LRRC8C mediates the transport of 2’3’cGAMP in T cells. T cells of Lrrc8c-/- mice have increased cell cycle progression, proliferation, survival, Ca2+ influx and cytokine production in vitro and enhanced T cell mediated immunity in vivo. We used RNA sequencing of CD4+ T cells from wild-type (WT) and Lrrc8c-/- mice to determine the effects of impaired cGAMP signaling in T cells. T cells of Lrrc8c-/- mice had impaired p53 signaling which was associated with decreased p53 expression. We found that uptake of 2’3’cGAMP and other CDNs via LRRC8C results in STING activation and p53 accumulation. Inhibition of STING in WT T cells recapitulates the phenotype of LRRC8C-deficient T cells whereas overexpression of p53 inhibits enhanced T cell function in the absence of LRRC8C. These findings establish cGAMP uptake through LRRC8C and subsequent STING-p53 signaling as a novel inhibitory signaling pathway in T cells and adaptive immunity.
2021-12-31 | GSE163679 | GEO