T cell migration requires ion and water influx to regulate actin polymerization

Osmotic stress influences microtubule drug response via WNK1 kinase signaling

Ion homeostasis is critical for numerous cellular processes, and disturbances in ionic balance underlie diverse pathological conditions, including cancer progression. Targeting ion homeostasis is even considered as a strategy to treat cancer. However, very little is known about how ion homeostasis may influence anticancer drug response. In a genome-wide CRISPR-Cas9 resistance drug screen, we identified and validated the master osmostress regulator WNK1 kinase as a modulator of the response to the mitotic inhibitor rigosertib. Osmotic stress and WNK1 inactivation lead to an altered response not only to rigosertib treatment but also to other microtubule-related drugs, minimizing the prototypical mitotic arrest produced by these compounds. This effect is due to an alteration in microtubule stability and polymerization dynamics, likely maintained by fluctuations in intracellular molecular crowding upon WNK1 inactivation. This promotes resistance to microtubule depolymerizing compounds, and increased sensitivity to microtubule stabilizing drugs. In summary, our data proposes WNK1 osmoregulation activity as an important modulator for microtubule-associated chemotherapy response.

Navigating confinement: Mechanotransduction and metabolic adaptation

Cell migration through confined spaces is a critical process influenced by the complex three-dimensional (3D) architecture of the local microenvironment and the surrounding extracellular matrix (ECM). Cells in vivo experience diverse fluidic signals, such as extracellular fluid viscosity, hydraulic resistance, and shear forces, as well as solid cues, like ECM stiffness and viscoelasticity. These fluidic and solid stressors activate mechanotransduction processes and regulate cell migration. They also drive metabolic reprogramming, dynamically altering glycolysis and oxidative phosphorylation to meet the cell's energy demands in different microenvironments. This review discusses recent advances on the mechanisms of cell migration in confinement and how confinement-induced cellular behavior leads to metabolic reprogramming.

WNK1-dependent water influx is required for CD4+ T cell activation and T cell-dependent antibody responses

Signaling from the T cell antigen receptor (TCR) on CD4+ T cells plays a critical role in adaptive immune responses by inducing T cell activation, proliferation, and differentiation. Here we demonstrate that WNK1, a kinase implicated in osmoregulation in the kidney, is required in T cells to support T-dependent antibody responses. We show that the canonical WNK1-OXSR1-STK39 kinase signaling pathway is required for TCR signaling in CD4+ T cells, their subsequent entry into the cell cycle, and suppression of the ATR-mediated G2/M cell cycle checkpoint. We show that the WNK1 pathway regulates ion influx leading to water influx, potentially through AQP3, and that water influx is required for TCR-induced signaling and cell cycle entry. Thus, TCR signaling via WNK1, OXSR1, STK39 and AQP3 leads to water entry that is essential for CD4+ T cell proliferation and hence T cell-dependent antibody responses.

Combined forces of hydrostatic pressure and actin polymerization drive endothelial tip cell migration and sprouting angiogenesis

Cell migration is a key process in the shaping and formation of tissues. During sprouting angiogenesis, endothelial tip cells invade avascular tissues by generating actomyosin-dependent forces that drive cell migration and vascular expansion. Surprisingly, endothelial cells (ECs) can still invade if actin polymerization is inhibited. In this study, we show that endothelial tip cells employ an alternative mechanism of cell migration that is dependent on Aquaporin (Aqp)-mediated water inflow and increase in hydrostatic pressure. In the zebrafish, ECs express aqp1a.1 and aqp8a.1 in newly formed vascular sprouts in a VEGFR2-dependent manner. Aqp1a.1 and Aqp8a.1 loss-of-function studies show an impairment in intersegmental vessels formation because of a decreased capacity of tip cells to increase their cytoplasmic volume and generate membrane protrusions, leading to delayed tip cell emergence from the dorsal aorta and slower migration. Further inhibition of actin polymerization resulted in a greater decrease in sprouting angiogenesis, indicating that ECs employ two mechanisms for robust cell migration in vivo. Our study thus highlights an important role of hydrostatic pressure in tissue morphogenesis.

Computational Identification of Migrating T cells in Spatial Transcriptomics Data

T cells are the central players in antitumor immunity, and effective tumor killing depends on their ability to infiltrate into the tumor microenvironment (TME) while maintaining normal cytotoxicity. However, late-stage tumors develop immunosuppressive mechanisms that impede T cell movement and induce exhaustion. Investigating T cell migration in human tumors in vivo could provide novel insights into tumor immune escape, although it remains a challenging task. In this study, we developed ReMiTT, a computational method that leverages spatial transcriptomics data to track T cell migration patterns within tumor tissue. Applying ReMiTT to multiple tumor samples, we identified potential migration trails. On these trails, chemokines that promote T-cell trafficking display an increasing trend. Additionally, we identified key genes and pathways enriched on these migration trails, including those involved in cytoskeleton rearrangement, leukocyte chemotaxis, cell adhesion, leukocyte migration, and extracellular matrix (ECM) remodeling. Furthermore, we characterized the phenotypes of T cells along these trails, showing that the migrating T cells are highly proliferative. Our findings introduce a novel approach for studying T cell migration and interactions within the tumor microenvironment (TME), offering valuable insights into tumor-immune dynamics.

Understanding the interplay between extracellular matrix topology and tumor-immune interactions: Challenges and opportunities

Modern cancer management comprises a variety of treatment strategies. Immunotherapy, while successful at treating many cancer subtypes, is often hindered by tumor immune evasion and T cell exhaustion as a result of an immunosuppressive tumor microenvironment (TME). In solid malignancies, the extracellular matrix (ECM) embedded within the TME plays a central role in T cell recognition and cancer growth by providing structural support and regulating cell behavior. Relative to healthy tissues, tumor associated ECM signatures include increased fiber density and alignment. These and other differentiating features contributed to variation in clinically observed tumor-specific ECM configurations, collectively referred to as Tumor-Associated Collagen Signatures (TACS) 1-3. TACS is associated with disease progression and immune evasion. This review explores our current understanding of how ECM geometry influences the behaviors of both immune cells and tumor cells, which in turn impacts treatment efficacy and cancer evolutionary progression. We discuss the effects of ECM remodeling on cancer cells and T cell behavior and review recent in silico models of cancer-immune interactions.

The biophysics of cell motility through mechanochemically challenging environments

Challenging mechanochemical environments (i.e., with varied mechanical and adhesive properties) are now known to induce a wide range of adaptive phenomena in motile cells. For instance, confinement and low adhesion may trigger a phenotypic transition to fast amoeboid (leader bleb-based) migration. The molecular mechanisms that underly these phenomena are beginning to be understood. Due to its size, the mechanical properties of the nucleus have been shown to limit and facilitate cell migration. Additionally, the activity of various transient receptor potential (TRP) channels is now known to be integral to cell migration in response to a multitude of biophysical stimuli. How cells integrate signals from the nucleus and plasma membrane, however, is unclear. The development of therapeutics that suppress cancer or enhance immune cell migration for immuno-oncology applications, etc., will require additional work to completely understand the molecular mechanisms that enable cells to navigate mechanochemically challenging environments.

Pump up the volume

An influx of water molecules can help immune cells called neutrophils to move to where they are needed in the body.

Activin A, a Novel Chemokine, Induces Mouse NK Cell Migration via AKT and Calcium Signaling

Natural killer (NK) cells can migrate quickly to the tumor site to exert cytotoxic effects on tumors, and some chemokines, including CXCL8, CXCL10 or and CXCL12, can regulate the migration of NK cells. Activin A, a member of the transforming growth factor β (TGF-β) superfamily, is highly expressed in tumor tissues and involved in tumor development and immune cell activation. In this study, we focus on the effects of activin A on NK cell migration. In vitro, activin A induced NK cell migration and invasion, promoted cell polarization and inhibited cell adhesion. Moreover, activin A increased Ca2+, p-SMAD3 and p-AKT levels in NK cells. An AKT inhibitor and Ca2+ chelator partially blocked activin A-induced NK cell migration. In vivo, exogenous activin A increased tumor-infiltrating NK cells in NS-1 cell solid tumors and inhibited tumor growth, and blocking endogenous activin A with anti-activin A antibody reduced tumor-infiltrating NK cells in 4T-1 cell solid tumors. These results suggest that activin A induces NK cell migration through AKT signaling and calcium signaling and may enhance the antitumor effect of NK cells by increasing tumor-infiltrating NK cells.

Water channel aquaporin 4 is required for T cell receptor mediated lymphocyte activation

Aquaporins are a family of ubiquitously expressed transmembrane water channels implicated in a broad range of physiological functions. We have previously reported that aquaporin 4 (AQP4) is expressed on T cells and that treatment with a small molecule AQP4 inhibitor significantly delays T cell mediated heart allograft rejection. Using either genetic deletion or small molecule inhibitor, we show that AQP4 supports T cell receptor mediated activation of both mouse and human T cells. Intact AQP4 is required for optimal T cell receptor (TCR)-related signaling events, including nuclear translocation of transcription factors and phosphorylation of proximal TCR signaling molecules. AQP4 deficiency or inhibition impairs actin cytoskeleton rearrangements following TCR crosslinking, causing inferior TCR polarization and a loss of TCR signaling. Our findings reveal a novel function of AQP4 in T lymphocytes and identify AQP4 as a potential therapeutic target for preventing TCR-mediated T cell activation.