WNK1 kinase balances T cell adhesion versus migration in vivo

Inhibition of WNK Kinases in NK Cells Disrupts Cellular Osmoregulation and Control of Tumor Metastasis

INTRODUCTION

The serine/threonine with-no-lysine (WNK) kinase family function in blood pressure control, electrolyte homeostasis, and cellular osmoregulation. These kinases and their downstream effectors are considered promising therapeutic targets in hypertension and stroke. However, the role of WNK kinases in immune cells remains poorly understood.

METHODS

Using the small-molecule WNK kinase inhibitors WNK463 and WNK-IN-11, we investigated how WNK kinase inhibition affects natural killer (NK) cell physiology.

RESULTS

WNK kinase inhibition with WNK463 or WNK-IN-11 significantly decreased IL-2-activated NK cell volume, motility, and cytolytic activity. Treatment of NK cells with these inhibitors induced autophagy by activating AMPK and inhibiting mTOR signaling. Moreover, WNK kinase inhibition increased phosphorylation of Akt and c-Myc by misaligning activity of activating kinases and inhibitory phosphatases. Treatment of tumor-bearing mice with WNK463 impaired tumor metastasis control by adoptively transferred NK cells.

CONCLUSION

The catalytic activity of WNK kinases has a critical role of multiple aspects of NK cell physiology and their pharmacologic inhibition negatively impacts NK cell function.

Chemokine-mediated F-actin dynamics, polarity, and migration in B lymphocytes depend on WNK1 signaling

Ligand-engaged chemokine receptors trigger nucleotide exchange in heterotrimeric Gαi proteins, which stimulates cytoskeletal reorganization and cell polarity changes. To better understand the signaling events responsible for these cellular changes, we focused on early changes in F-actin dynamics after engagement of the chemokine receptor CXCR5 in murine splenic B cells. Within 10 seconds of exposure to the CXCR5 ligand CXCL13, three-dimensional lamellar-like pseudopods and F-actin-rich ridges appeared. The transient F-actin increase depended on Gαi2/3 signaling, the PI3K/AKT pathway, ERK activation, phospholipase C activity, and Rac1/2 activation mediated by Dock2 (dedicator of cytokinesis 2). Immunoblot analyses identified the kinase WNK1 (with no lysine kinase 1) as a potential early AKT effector. Treating B cells with specific WNK inhibitors disrupted F-actin dynamics and impaired B cell polarity, motility, and chemotaxis. These changes were mimicked in a murine B cell line by CRISPR-Cas9 gene editing of Wnk1, which also suggested that WNK1 contributed to B cell proliferation. Administration of a single dose of a WNK inhibitor transiently reduced B cell motility and polarity in the lymph nodes of live mice. These results indicate that WNK1 signaling maintains B cell responsiveness to CXCL13 and suggest that pharmacological inhibition of WNK1, which is involved in cancer progression and blood pressure regulation, may affect humoral immunity.

Predictive and Experimental Motif Interaction Analysis Identifies Functions of the WNK-OSR1/SPAK Pathway

The WNK-OSR1/SPAK protein kinase signaling pathway regulates ion homeostasis and cell volume, but its other functions are poorly understood. To uncover undefined signaling functions of the pathway we analyzed the binding specificity of the conserved C-terminal (CCT) domains of OSR1 and SPAK to find all possible interaction motifs in human proteins. These kinases bind the core consensus sequences R-F-x-V/I and R-x-F-x-V/I. Motifs were ranked based on sequence, conservation, cellular localization, and solvent accessibility. Out of nearly 3,700 motifs identified, 90% of previously published motifs were within the top 2% of those predicted. Selected candidates (TSC22D1, CAVIN1, ATG9A, NOS3, ARHGEF5) were tested. Upstream kinases WNKs 1-4 and their close relatives, the pseudokinases NRBP1/2, contain CCT-like domains as well. We identified additional distinct motif variants lacking the conserved arginine previously thought to be required, and found that the NRBP1 CCT-like domain binds TSC22D1 via the same motif as OSR1 and SPAK. Our results further highlight the rich and diverse functionality of CCT and CCT-like domains in connecting WNK signaling to cellular processes.

Isoform-independent promotion of contractility and proliferation, and suppression of survival by with no lysine/K kinases in prostate stromal cells

With no lysine/K kinases (WNKs) promote vasocontraction and vascular smooth muscle cell proliferation. In the prostate, smooth muscle contraction and growth may be critical for the development and medical treatment of voiding symptoms in benign prostatic hyperplasia. Here, we examined the effects of isoform-specific WNK silencing and of the WNK inhibitor WNK463 on growth-related functions and contraction in prostate stromal cells, and in human prostate tissues. Impacts of WNK silencing by transfection of cultured stromal cells with isoform-specific siRNAs were qualitatively and quantitatively similar for each WNK isoform. Effects of silencing were largest on cell death (3-5 fold increase in annexin V-positive/7-AAD-positive cells), on proliferation rate, Ki-67 mRNA expression and actin organization (reduced around two-thirds). Contraction in matrix contraction assays and viability were reduced to a lower degree (approximately half), but again to a similar extent for each WNK isoform. Effects of silencing were quantitatively and qualitatively reproduced by 10 μM WNK463, while 1 μM still induced cell death and breakdown in actin organization, without affecting proliferation or viability. Using 500 nM and 10 μM, WNK463 partly inhibited neurogenic and U46619-induced contractions of human prostate tissues (around half), while inhibition of α1-adrenergic contractions (around half) was limited to 10 μM. All four WNK isoforms suppress cell death and promote proliferation in prostate stromal cells. WNK-driven contraction of stromal cells appears possible, even though to a limited extent. Outcomes of isoform-specific WNK silencing can be fully reproduced by WNK463, including inhibition of smooth muscle contraction in human prostate tissues, but require high concentrations.

The Role of Ion-Transporting Proteins in Human Disease

This Special Issue focuses on the significance of ion-transporting proteins, such as ion channels and transporters, providing evidence for their significant contribution to bodily and cellular functions via the regulation of signal transduction and ionic environments [...].

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

Migration of T cells is essential for their ability to mount immune responses. Chemokine-induced T cell migration requires WNK1, a kinase that regulates ion influx into the cell. However, it is not known why ion entry is necessary for T cell movement. Here we show that signaling from the chemokine receptor CCR7 leads to activation of WNK1 and its downstream pathway at the leading edge of migrating CD4+ T cells, resulting in ion influx and water entry by osmosis. We propose that WNK1-induced water entry is required to swell the membrane at the leading edge, generating space into which actin filaments can polymerize, thereby facilitating forward movement of the cell. Given the broad expression of WNK1 pathway proteins, our study suggests that ion and water influx are likely to be essential for migration in many cell types, including leukocytes and metastatic tumor cells.

Physiological roles of chloride ions in bodily and cellular functions

Physiological roles of Cl-, a major anion in the body, are not well known compared with those of cations. This review article introduces: (1) roles of Cl- in bodily and cellular functions; (2) the range of cytosolic Cl- concentration ([Cl-]c); (3) whether [Cl-]c could change with cell volume change under an isosmotic condition; (4) whether [Cl-]c could change under conditions where multiple Cl- transporters and channels contribute to Cl- influx and efflux in an isosmotic state; (5) whether the change in [Cl-]c could be large enough to act as signals; (6) effects of Cl- on cytoskeletal tubulin polymerization through inhibition of GTPase activity and tubulin polymerization-dependent biological activity; (7) roles of cytosolic Cl- in cell proliferation; (8) Cl--regulatory mechanisms of ciliary motility; (9) roles of Cl- in sweet/umami taste receptors; (10) Cl--regulatory mechanisms of with-no-lysine kinase (WNK); (11) roles of Cl- in regulation of epithelial Na+ transport; (12) relationship between roles of Cl- and H+ in body functions.

Role of Female Sex Hormones and Immune Response in Salt-Sensitive Hypertension Development: Evidence from Experimental Models

PURPOSEOF REVIEW

Female sex hormones have systemic effects unrelated to their reproductive function. We describe experiences of different research groups and our own, on aspects related to the importance of female sex hormones on blood pressure (BP) regulation and salt-sensitivity-mediated BP response and salt sensitivity without alterations in BP, as well as renal sodium handling and interactions with the immune system.

RECENT FINDINGS

Changes in sodium intake in normotensive premenopausal women cause more BP variations than in men. After menopause, women often develop arterial hypertension (HT) with a profile of sodium sensitivity. Besides, experimental results have shown that in adult rat models resembling the postmenopausal hormonal state induced by ovariectomy, controlling BP is not enough to avoid renal and other tissue infiltration with immune cells, which does not occur when sodium intake is low or normal. Therefore, excess sodium promotes an inflammatory state with the involvement of immune cells. The evidence of activation of adaptive immunity, besides changes in T cell subpopulations, includes changes in sodium transporters and receptors. More studies are needed to evaluate the particular sodium sensitivity of women and its meaning. Changes in lifestyle and sodium intake reduction are the main therapeutic steps. However, to face the actual burden of salt-sensitive HT in postmenopausal women and its associated inflammatory/immune changes, it seems reasonable to work on immune cell activity by considering the peripheral blood mononuclear cell phenotypes of molecules and transport proteins related to sodium handle, both to screen for and treat cell activation.

B cell-intrinsic requirement for WNK1 kinase in antibody responses in mice

Migration and adhesion play critical roles in B cells, regulating recirculation between lymphoid organs, migration within lymphoid tissue, and interaction with CD4+ T cells. However, there is limited knowledge of how B cells integrate chemokine receptor and integrin signaling with B cell activation to generate efficient humoral responses. Here, we show that the WNK1 kinase, a regulator of migration and adhesion, is essential in B cells for T-dependent and -independent antibody responses. We demonstrate that WNK1 transduces signals from the BCR, CXCR5, and CD40, and using intravital imaging, we show that WNK1 regulates migration of naive and activated B cells, and their interactions with T cells. Unexpectedly, we show that WNK1 is required for BCR- and CD40-induced proliferation, acting through the OXSR1 and STK39 kinases, and for efficient B cell-T cell collaboration in vivo. Thus, WNK1 is critical for humoral immune responses, by regulating B cell migration, adhesion, and T cell-dependent activation.

Aberrant expression of WNK lysine deficient protein kinase 1 is associated with poor prognosis of colon adenocarcinoma

BACKGROUNDS

WNK1 (WNK lysine deficient protein kinase 1) is a kind of protein kinase and participates in angiogenesis, having a potent tumor promoting role. WNK1 is ubiquitously expressed, and its upregulated expression has been reported in several tumor types.

AIMS

Here, we aimed to investigate the correlation between WNK1 expression and colon adenocarcinoma (COAD) progression.

METHODS

In the current study, WNK1 expression was evaluated by immunohistochemically in adjacent normal colonic mucosae and primary adenocarcinomas. The effect of WNK1 on overall survival (OS) and its associations with the clinicopathological parameters were analyzed in a retrospective cohort of COAD patients (n = 185). The tumor-related effects of WNK1 in COAD were further tested via cellular and mice experiments.

RESULTS

According to our cohort, higher WNK1 expression was significantly associated with unfavorable prognostic factors, such as high pT stage, pN stage, as well as shorter OS. Moreover, WNK1 exhibited tumor promoting role in COAD cancer cell lines as well as in nude mice. Silencing WNK1 can significantly inhibit the proliferation of COAD both in vitro and in vivo.

CONCLUSIONS

In all, WNK1 acts as a tumor promoter and may be used as a COAD prognostic biomarker.

CTLs From Patients With Atherosclerosis Show Elevated Adhesiveness and Distinct Integrin Expression Patterns on 2D Substrates

Atherosclerosis is the major cause of cardiovascular disease that is characterized by plaque formation in the blood vessel wall. Atherosclerotic plaques represent sites of chronic inflammation with diverse cell content that is shifted toward the prevalence of cytotoxic T-lymphocytes (CTLs) upon plaque progression. The studies of CTL recruitment to atherosclerotic plaques require adequate in vitro models accounting for CTL interactions with chemokine-ligands and extracellular matrix fibers via surface chemokine receptors and integrins. Here we applied such a model by investigating CTL adhesion and migration on six types of coated surfaces. We assessed adhesion and motility metrics, the expression of chemokine receptors, and integrins in CTLs of patients with atherosclerosis and healthy donors. Using fibronectin, platelet-poor plasma from patients with atherosclerosis, and conditioned medium from atherosclerotic plaques we revealed the role of substrate in CTL adhesiveness: fibronectin alone and fibronectin combined with platelet-poor plasma and conditioned medium elevated the CTL adhesiveness - in patients the elevation was significantly higher than in healthy donors (p = 0.02, mixed 2-way ANOVA model). This was in line with our finding that the expression levels of integrin-coding mRNAs were elevated in the presence of fibronectin (p < 0.05) and ITGB1, ITGA1, and ITGA4 were specifically upregulated in patients compared to healthy donors (p < 0.01). Our experimental model did not affect the expression levels of mRNAs CCR4, CCR5, and CX3CR1 coding the chemokine receptors that drive T-lymphocyte migration to plaques. Thus, we demonstrated the substrate-dependence of integrin expression and discriminated CTLs from patients and healthy donors by adhesion parameters and integrin expression levels.

WNK1 in Malignant Behaviors: A Potential Target for Cancer?

Metastasis is the major cause of mortality in cancer patients. Analyses of mouse models and patient data have implicated the protein kinase WNK1 as one of a handful of genes uniquely linked to a subset of invasive cancers. WNK1 signaling pathways are widely implicated in the regulation of ion co-transporters and in controlling cell responses to osmotic stress. In this review we will discuss its actions in tumor malignancy in human cancers and present evidence for its function in invasion, migration, angiogenesis and mesenchymal transition.

Immune Checkpoint Proteins, Metabolism and Adhesion Molecules: Overlooked Determinants of CAR T-Cell Migration?

Adoptive transfer of T cells genetically engineered to express chimeric antigen receptors (CAR) has demonstrated striking efficacy for the treatment of several hematological malignancies, including B-cell lymphoma, leukemia, and multiple myeloma. However, many patients still do not respond to this therapy or eventually relapse after an initial remission. In most solid tumors for which CAR T-cell therapy has been tested, efficacy has been very limited. In this context, it is of paramount importance to understand the mechanisms of tumor resistance to CAR T cells. Possible factors contributing to such resistance have been identified, including inherent CAR T-cell dysfunction, the presence of an immunosuppressive tumor microenvironment, and tumor-intrinsic factors. To control tumor growth, CAR T cells have to migrate actively enabling a productive conjugate with their targets. To date, many cells and factors contained within the tumor microenvironment have been reported to negatively control the migration of T cells and their ability to reach cancer cells. Recent evidence suggests that additional determinants, such as immune checkpoint proteins, cellular metabolism, and adhesion molecules, may modulate the motility of CAR T cells in tumors. Here, we review the potential impact of these determinants on CAR T-cell motility, and we discuss possible strategies to restore intratumoral T-cell migration with a special emphasis on approaches targeting these determinants.

Forward Genetics in Apicomplexa Biology: The Host Side of the Story

Forward genetic approaches have been widely used in parasitology and have proven their power to reveal the complexities of host-parasite interactions in an unbiased fashion. Many aspects of the parasite's biology, including the identification of virulence factors, replication determinants, antibiotic resistance genes, and other factors required for parasitic life, have been discovered using such strategies. Forward genetic approaches have also been employed to understand host resistance mechanisms to parasitic infection. Here, we will introduce and review all forward genetic approaches that have been used to identify host factors involved with Apicomplexa infections, which include classical genetic screens and QTL mapping, GWAS, ENU mutagenesis, overexpression, RNAi and CRISPR-Cas9 library screens. Collectively, these screens have improved our understanding of host resistance mechanisms, immune regulation, vaccine and drug designs for Apicomplexa parasites. We will also discuss how recent advances in molecular genetics give present opportunities to further explore host-parasite relationships.

EP3 enhances adhesion and cytotoxicity of NK cells toward hepatic stellate cells in a murine liver fibrosis model

Natural killer (NK) cells exhibit antifibrotic properties in liver fibrosis (LF) by suppressing activated hepatic stellate cell (HSC) populations. Prostaglandin E2 (PGE2) plays a dual role in innate and adaptive immunity. Here, we found that E-prostanoid 3 receptor (EP3) was markedly downregulated in NK cells from liver fibrosis mice and patients with liver cirrhosis. NK cell-specific deletion of EP3 aggravated hepatic fibrogenesis in mouse models of LF. Loss of EP3 selectively reduced the cytotoxicity of the CD27+CD11b+ double positive (DP) NK subset against activated HSCs. Mechanistically, deletion of EP3 impaired the adhesion and cytotoxicity of DP NK cells toward HSCs through modulation of Itga4-VCAM1 binding. EP3 upregulated Itga4 expression in NK cells through promoting Spic nuclear translocation via PKC-mediated phosphorylation of Spic at T191. Activation of EP3 by sulprostone alleviated CCL4-induced liver fibrosis in mice. Thus, EP3 is required for adhesion and cytotoxicity of NK cells toward HSCs and may serve as a therapeutic target for the management of LF.

The WNK1 kinase regulates the stability of transcription factors during wound healing of human corneal epithelial cells

Due to its superficial anatomical localization, the cornea is continuously subjected to injuries. Damages to the corneal epithelium trigger important changes in the composition of the extracellular matrix to which the basal human corneal epithelial cells (hCECs) attach. These changes are perceived by membrane-bound integrins and ultimately lead to re-epithelialization of the injured epithelium through intracellular signalin. Among the many downstream targets of the integrin-activated signaling pathways, WNK1 is the kinase whose activity is the most strongly increased during corneal wound healing. We previously demonstrated that pharmacological inhibition of WNK1 prevents proper closure of wounded human tissue-engineered cornea in vitro. In the present study, we investigated the molecular mechanisms by which WNK1 contributes to corneal wound healing. By exploiting transcription factors microarrays, electrophoretic mobility-shift assay, and gene profiling analyses, we demonstrated that the DNA binding properties and expression of numerous transcription factors (TFs), including the well-known, ubiquitous TFs specific protein 1 (Sp1) and activator protein 1 (AP1), were reduced in hCECs upon WNK1 inhibition by WNK463. This process appears to be mediated at least in part by alteration in both the ubiquitination and glycosylation status of these TFs. These changes in TFs activity and expression impacted the transcription of several genes, including that encoding the α5 integrin subunit, a well-known target of both Sp1 and AP1. Gene profiling revealed that only a moderate number of genes in hCECs had their level of expression significantly altered in response to WNK463 exposition. Interestingly, analysis of the microarray data for these deregulated genes using the ingenuity pathway analysis software predicted that hCECs would stop migrating and proliferating but differentiate more when they are grown in the presence of the WNK1 inhibitor. These results demonstrate that WNK1 plays a critical function by orienting hCECs into the appropriate biological response during the process of corneal wound healing.

The Tec Kinase Itk Integrates Naïve T Cell Migration and In Vivo Homeostasis

Naïve T cells (T_N) constitutively recirculate through secondary lymphatic organs (SLOs), where they scan dendritic cells (DCs) for cognate peptide-loaded major histocompatibility complexes (pMHC). Continuous trafficking between SLOs not only enables rapid clonal selection but also ensures T_N homeostasis by providing access to prosurvival signals from TCR, IL-7R, and the chemokine receptor CCR7. Inside the lymphoid tissue, CCR7-mediated T_N motility is mainly driven by the Rac activator DOCK2, with a separate contribution by a phosphoinositide-3-kinase γ (PI3Kγ)-dependent pathway. Tec tyrosine kinases and the Rac activator Tiam1 constitute prominent downstream effectors of PI3K signaling. Yet, the precise role of Tec kinase versus Tiam1 signaling during CCR7-mediated T_N migration and homeostasis remains incompletely understood. Here, we examined the function of the Tec family member interleukin-2-inducible T-cell kinase (Itk) and Tiam1 during T_N migration in vitro and in vivo using intravital microscopy. Itk deficiency caused a mild decrease in CCR7-triggered T_N migration, mirroring observations made with PI3Kγ;^-/- T cells, while lack of Tiam1 did not affect T_N motility. In silico modeling suggested that reduced migration in the absence of Itk does not result in a substantial decrease in the frequency of T_N encounters with DCs within the lymphoid tissue. In contrast, Itk was important to maintain in vivo homeostasis of CD4⁺ T_N, also in MHCII-deficient hosts. Taken together, our data suggest that Itk contributes to T_N migration and survival by integrating chemokine receptor and TCR signaling pathways.

Brd4 Regulates the Homeostasis of CD8+ T-Lymphocytes and Their Proliferation in Response to Antigen Stimulation

CD8+ T cells are major components of adaptive immunity and confer robust protective cellular immunity, which requires adequate T-cell numbers, targeted migration, and efficient T-cell proliferation. Altered CD8+ T-cell homeostasis and impaired proliferation result in dysfunctional immune response to infection or tumorigenesis. However, intrinsic factors controlling CD8+ T-cell homeostasis and immunity remain largely elusive. Here, we demonstrate the prominent role of Brd4 on CD8+ T cell homeostasis and immune response. By upregulating Myc and GLUT1 expression, Brd4 facilitates glucose uptake and energy production in mitochondria, subsequently supporting naïve CD8+ T-cell survival. Besides, Brd4 promotes the trafficking of naïve CD8+ T cells partially through maintaining the expression of homing receptors (CD62L and LFA-1). Furthermore, Brd4 is required for CD8+ T cell response to antigen stimulation, as Brd4 deficiency leads to a severe defect in clonal expansion and terminal differentiation by decreasing glycolysis. Importantly, as JQ1, a pan-BRD inhibitor, severely dampens CD8+ T-cell immune response, its usage as an anti-tumor agent or latency-reversing agent for human immunodeficiency virus type I (HIV-1) should be more cautious. Collectively, our study identifies a previously-unexpected role of Brd4 in the metabolic regulation of CD8+ T cell-mediated immune surveillance and also provides a potential immunomodulation target.

LFA-1 in T cell priming, differentiation, and effector functions

The integrin LFA-1 is crucial for T cell entry into mammalian lymph nodes and tissues, and for promoting interactions with antigen-presenting cells (APCs). However, it is increasingly evident that LFA-1 has additional key roles beyond the mere support of adhesion between T cells, the endothelium, and/or APCs. These include roles in homotypic T cell-T cell (T-T) communication, the induction of intracellular complement activity underlying Th1 effector cell polarization, and the support of long-lasting T cell memory. Here, we briefly summarize current knowledge of LFA-1 biology, discuss novel cytoskeletal regulators of LFA-1 functions, and review new aspects of LFA-1 mechanobiology that are relevant to its function in immunological synapses and in specific pathologies arising from LFA-1 dysregulation.

Ovariectomy and high salt increase blood pressure and alter sodium transport proteins in peripheral blood mononuclear cells of adult Wistar rats

NEW FINDINGS

What is the central question of this study? In a model of salt-sensitive hypertension in ovariectomized (oVx) adult Wistar rats, what is the expression of proteins related to sodium transport in peripheral blood mononuclear cells (PBMCs), and how does the response of proteins to high sodium intake compare with changes in blood pressure in intact female rats? What is the main finding and its importance? Sodium transport proteins in PBMCs react to high sodium and blood pressure markedly differently in oVx versus intact female rats. Protein expression shows sodium and pressure sensitivity. Renal immune cells increase in oVx under high salt.

ABSTRACT

Hypertension is a worldwide public health problem. High sodium consumption is associated with hypertension, and hypertensive mechanisms involve immunity cells. Peripheral blood mononuclear cells (PBMCs) are endowed with proteins related to sodium transport. We studied their abundance in PBMCs from intact (IF) or ovariectomized (oVx) adult Wistar rats under normal (NS) or high (HS) salt intake. Ovariectomy was performed at 60 days of life. At 145 days, one group of IF and oVx rats received NS or HS intake for 5 days. Another group of IF HS and oVx HS rats received hydralazine (HDZ) to reduce blood pressure (BP). Sodium balance and BP were recorded. Expression of Na⁺ ,K⁺ -ATPase (NKA), Na⁺ -K⁺ -2Cl^- cotransporter 1 (NKCC1), serum/glucocorticoid-regulated kinase 1 (SGK1), dopamine D1 like receptor (D1DR), CD4⁺ and CD8⁺ were determined in PBMCs and CD45⁺ leukocytes in renal tissue. IF HS rats showed increased natriuresis and normal BP. NKA and CD4⁺ expression diminished in IF HS. Instead, oVx HS rats had sodium retention and high BP and increased the expression of NKA, NKCC1, D1DR, CD4⁺ and CD8⁺ in PBMCs. Renal CD45⁺ leukocytes increased in oVx HS rats. HDZ decreased BP in all rats. Upon HDZ treatment, NKA did not change, NKCC1 decreased in oVx HS rats, while SGK1 increased in both IF HS and oVx HS rats. Hormonal background determines BP response and the expression of proteins related to sodium transport in PBMCs and renal immune cells at HS intake. The analysis of NKA, NKCC1 and SGK1 expression in PBMCs differentiated salt-sensitivity from BP variations.

Chloride sensing by WNK1 regulates NLRP3 inflammasome activation and pyroptosis

The NLRP3 inflammasome mediates the production of proinflammatory cytokines and initiates inflammatory cell death. Although NLRP3 is essential for innate immunity, aberrant NLRP3 inflammasome activation contributes to a wide variety of inflammatory diseases. Understanding the pathways that control NLRP3 activation will help develop strategies to treat these diseases. Here we identify WNK1 as a negative regulator of the NLRP3 inflammasome. Macrophages deficient in WNK1 protein or kinase activity have increased NLRP3 activation and pyroptosis compared with control macrophages. Mice with conditional knockout of WNK1 in macrophages have increased IL-1β production in response to NLRP3 stimulation compared with control mice. Mechanistically, WNK1 tempers NLRP3 activation by balancing intracellular Cl- and K+ concentrations during NLRP3 activation. Collectively, this work shows that the WNK1 pathway has a critical function in suppressing NLRP3 activation and suggests that pharmacological inhibition of this pathway to treat hypertension might have negative clinical implications.

Phosphorylated WNK kinase networks in recoded bacteria recapitulate physiological function

Advances in genetic code expansion have enabled the production of proteins containing site-specific, authentic post-translational modifications. Here, we use a recoded bacterial strain with an expanded genetic code to encode phosphoserine into a human kinase protein. We directly encode phosphoserine into WNK1 (with-no-lysine [K] 1) or WNK4 kinases at multiple, distinct sites, which produced activated, phosphorylated WNK that phosphorylated and activated SPAK/OSR kinases, thereby synthetically activating this human kinase network in recoded bacteria. We used this approach to identify biochemical properties of WNK kinases, a motif for SPAK substrates, and small-molecule kinase inhibitors for phosphorylated SPAK. We show that the kinase inhibitors modulate SPAK substrates in cells, alter cell volume, and reduce migration of glioblastoma cells. Our work establishes a protein-engineering platform technology that demonstrates that synthetically active WNK kinase networks can accurately model cellular systems and can be used more broadly to target networks of phosphorylated proteins for research and discovery.

GABAergic signaling by cells of the immune system: more the rule than the exception

Gamma-aminobutyric acid (GABA) is best known as an essential neurotransmitter in the evolved central nervous system (CNS) of vertebrates. However, GABA antedates the development of the CNS as a bioactive molecule in metabolism and stress-coupled responses of prokaryotes, invertebrates and plants. Here, we focus on the emerging findings of GABA signaling in the mammalian immune system. Recent reports show that mononuclear phagocytes and lymphocytes, for instance dendritic cells, microglia, T cells and NK cells, express a GABAergic signaling machinery. Mounting evidence shows that GABA receptor signaling impacts central immune functions, such as cell migration, cytokine secretion, immune cell activation and cytotoxic responses. Furthermore, the GABAergic signaling machinery of leukocytes is implicated in responses to microbial infection and is co-opted by protozoan parasites for colonization of the host. Peripheral GABA signaling is also implicated in inflammatory conditions and diseases, such as type 1 diabetes, rheumatoid arthritis and cancer cell metastasis. Adding to its role in neurotransmission, growing evidence shows that the non-proteinogenic amino acid GABA acts as an intercellular signaling molecule in the immune system and, as an interspecies signaling molecule in host–microbe interactions. Altogether, the data raise the assumption of conserved GABA signaling in a broad range of mammalian cells and diversification of function in the immune system.

Control of Podocyte and Glomerular Capillary Wall Structure and Elasticity by WNK1 Kinase

Cytoskeletal structure and its regulation are essential for maintenance of the differentiated state of specific types of cells and their adaptation to physiologic and pathophysiologic conditions. Renal glomerular capillaries, composed of podocytes, endothelial cells, and the glomerular basement membrane, have distinct structural and biophysical properties and are the site of injury in many glomerular diseases. Calcineurin inhibitors, immunosuppressant drugs used for organ transplantation and auto-immune diseases, can protect podocytes and glomerular capillaries from injury by preserving podocyte cytoskeletal structure. These drugs cause complications including hypertension and hyperkalemia which are mediated by WNK (With No Lysine) kinases as well as vasculopathy with glomerulopathy. WNK kinases and their target kinases oxidative stress-responsive kinase 1 (OSR1) and SPS1-related proline/alanine-rich kinase (SPAK) have fundamental roles in angiogenesis and are activated by calcineurin inhibitors, but the actions of these agents on kidney vasculature, and glomerular capillaries are not fully understood. We investigated WNK1 expression in cultured podocytes and isolated mouse glomerular capillaries to determine if WNK1 contributes to calcineurin inhibitor-induced preservation of podocyte and glomerular structure. WNK1 and OSR1/SPAK are expressed in podocytes, and in a pattern similar to podocyte synaptopodin in glomerular capillaries. Calcineurin inhibitors increased active OSR1/SPAK in glomerular capillaries, the Young’s modulus (E) of glomeruli, and the F/G actin ratio, effects all blocked by WNK inhibition. In glomeruli, WNK inhibition caused reduced and irregular synaptopodin-staining, abnormal capillary and foot process structures, and increased deformability. In cultured podocytes, FK506 activated OSR1/SPAK, increased lamellipodia, accelerated cell migration, and promoted traction force. These actions of FK506 were reduced by depletion of WNK1. Collectively, these results demonstrate the importance of WNK1 in regulation of the podocyte actin cytoskeleton, biophysical properties of glomerular capillaries, and slit diaphragm structure, all of which are essential to normal kidney function.

The Human Tissue-Engineered Cornea (hTEC): Recent Progress

Each day, about 2000 U.S. workers have a job-related eye injury requiring medical treatment. Corneal diseases are the fifth cause of blindness worldwide. Most of these diseases can be cured using one form or another of corneal transplantation, which is the most successful transplantation in humans. In 2012, it was estimated that 12.7 million people were waiting for a corneal transplantation worldwide. Unfortunately, only 1 in 70 patients received a corneal graft that same year. In order to provide alternatives to the shortage of graftable corneas, considerable progress has been achieved in the development of living corneal substitutes produced by tissue engineering and designed to mimic their in vivo counterpart in terms of cell phenotype and tissue architecture. Most of these substitutes use synthetic biomaterials combined with immortalized cells, which makes them dissimilar from the native cornea. However, studies have emerged that describe the production of tridimensional (3D) tissue-engineered corneas using untransformed human corneal epithelial cells grown on a totally natural stroma synthesized by living corneal fibroblasts, that also show appropriate histology and expression of both extracellular matrix (ECM) components and integrins. This review highlights contributions from laboratories working on the production of human tissue-engineered corneas (hTECs) as future substitutes for grafting purposes. It overviews alternative models to the grafting of cadaveric corneas where cell organization is provided by the substrate, and then focuses on their 3D counterparts that are closer to the native human corneal architecture because of their tissue development and cell arrangement properties. These completely biological hTECs are therefore very promising as models that may help understand many aspects of the molecular and cellular mechanistic response of the cornea toward different types of diseases or wounds, as well as assist in the development of novel drugs that might be promising for therapeutic purposes.

WNK1-TAK1 signaling suppresses lipopolysaccharide-induced cytokine production and classical activation in macrophages

With-no-lysine kinase (WNK) plays important roles in regulating electrolyte homeostasis, cell signaling, survival, and proliferation. It has been recently demonstrated that WNK1, a member of the WNK family, modifies the function of immune cells. Here we report that in macrophages, WNK1 has suppressive effects on lipopolysaccharide (LPS)-induced inflammatory responses via TGFβ-activated kinase 1 (TAK1)-mediated activation of nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathway. We found that WNK1 heterozygous (WNK1^+/-) mice produced excessive proinflammatory cytokines in an experimental LPS-induced sepsis model, and peritoneal macrophages isolated from WNK1^+/- mice produced higher levels of LPS-induced cytokines and NOS2 expression as canonical proinflammatory M1 macrophage markers. We confirmed that small hairpin RNA (shRNA)-mediated knockdown of WNK1 activated LPS-induced cytokine production and NOS2 expression in RAW 264.7 macrophages. Moreover, we demonstrated that WNK1 knockdown increased the nuclear translocation of NF-κB and activated the p38 and Jun N-terminal kinase (JNK) MAPK signaling pathway and that a TAK1 inhibitor diminished these effects of WNK1 knockdown. These results suggest that WNK1 acts as a physiologic immune modulator via interactions with TAK1. WNK1 may be a therapeutic target against the cytokine storm caused by sepsis.

Compounds from Natural Sources as Protein Kinase Inhibitors

The advantage of natural compounds is their lower number of side-effects when compared to most synthetic substances. Therefore, over the past several decades, the interest in naturally occurring compounds is increasing in the search for new potent drugs. Natural compounds are playing an important role as a starting point when developing new selective compounds against different diseases. Protein kinases play a huge role in several diseases, like cancers, neurodegenerative diseases, microbial infections, or inflammations. In this review, we give a comprehensive view of natural compounds, which are/were the parent compounds in the development of more potent substances using computational analysis and SAR studies.

The Important Role of Perituberal Tissue in Epileptic Patients with Tuberous Sclerosis Complex by the Transcriptome Analysis

Epilepsy is most common in patients with tuberous sclerosis complex (TSC). However, in addition to the challenging treatment, the pathogenesis of epilepsy is still controversial. To determine the transcriptome characteristics of perituberal tissue (PT) and clarify its role in the pathogenesis of epilepsy, GSE16969 was downloaded from the GEO database for further study by comprehensive bioinformatics analysis. Identification of differentially expressed genes (DEGs), functional enrichment analysis, construction of protein-protein interaction (PPI) network, and selection of Hub genes were performed using R language, Metascape, STRING, and Cytoscape, respectively. Comparing with cortical tuber (CT), 220 DEGs, including 95 upregulated and 125 downregulated genes, were identified in PT and mainly enriched in collagen-containing extracellular matrix and positive regulation of receptor-mediated endocytosis, as well as the pathways of ECM-receptor interaction and neuroactive ligand-receptor interaction. As for normal cortex (NC), 1549 DEGs, including 30 upregulated and 1519 downregulated genes, were identified and mainly enriched in presynapse, dendrite and axon, and also the pathways of dopaminergic synapse and oxytocin signaling pathway. In the PPI network, 4 hub modules were found between PT and CT, and top 5 hub modules were selected between PT and NC. C3, APLNR, ANXA2, CD44, CLU, CP, MCHR2, HTR1E, CTSG, APP, and GNG2 were identified as Hub genes, of which, C3, CD44, ANXA2, HTR1E, and APP were identified as Hub-BottleNeck genes. In conclusion, PT has the unique characteristics different from CT and NC in transcriptome and makes us further understand its importance in the TSC-associated epilepsy.

Critical role of WNK1 in MYC-dependent early mouse thymocyte development

WNK1, a kinase that controls kidney salt homeostasis, also regulates adhesion and migration in CD4⁺ T cells. Wnk1 is highly expressed in thymocytes, and since migration is important for thymocyte maturation, we investigated a role for WNK1 in mouse thymocyte development. We find that WNK1 is required for the transition of double negative (DN) thymocytes through the β-selection checkpoint and subsequent proliferation and differentiation into double positive (DP) thymocytes. Furthermore, we show that WNK1 negatively regulates LFA1-mediated adhesion and positively regulates CXCL12-induced migration in DN thymocytes. Despite this, migration defects of WNK1-deficient thymocytes do not account for the developmental arrest. Instead, we show that in DN thymocytes WNK1 transduces pre-TCR signals via OXSR1 and STK39 kinases, and the SLC12A2 ion co-transporter that are required for post-transcriptional upregulation of MYC and subsequent proliferation and differentiation into DP thymocytes. Thus, a pathway regulating ion homeostasis is a critical regulator of thymocyte development.

Phosphatidic acid-dependent localization and basal de-phosphorylation of RA-GEFs regulate lymphocyte trafficking

Background

Lymphocytes circulate between peripheral lymphoid tissues via blood and lymphatic systems, and chemokine-induced migration is important in trafficking lymphocytes to distant sites. The small GTPase Rap1 is important in mediating lymphocyte motility, and Rap1-GEFs are involved in chemokine-mediated Rap1 activation. Here, we describe the roles and mechanisms of Rap1-GEFs in lymphocyte trafficking.

Results

In this study, we show that RA-GEF-1 and 2 (also known as Rapgef2 and 6) are key guanine nucleotide exchange factors (GEF) for Rap1 in lymphocyte trafficking. Mice harboring T cell-specific knockouts of Rapgef2/6 demonstrate defective homing and egress of T cells. Sphingosine-1-phosphate (S1P) as well as chemokines activates Rap1 in a RA-GEF-1/2-dependent manner, and their deficiency in T cells impairs Mst1 phosphorylation, cell polarization, and chemotaxis toward S1P gradient. On the other hand, B cell-specific knockouts of Rapgef2/6 impair chemokine-dependent retention of B cells in the bone marrow and passively facilitate egress. Phospholipase D2-dependent production of phosphatidic acid by these chemotactic factors determines spatial distribution of Rap1-GTP subsequent to membrane localization of RA-GEFs and induces the development of front membrane. On the other hand, basal de-phosphorylation of RA-GEFs is necessary for chemotactic factor-dependent increase in GEF activity for Rap1.

Conclusions

We demonstrate here that subcellular distribution and activation of RA-GEFs are key factors for a directional movement of lymphocytes and that phosphatidic acid is critical for membrane translocation of RA-GEFs with chemokine stimulation.

The Role of Integrin α4β7 Signaling in Human Immunodeficiency Virus-1 Pathogenesis and Viral Entry in Primary CD4+ T Cells As Revealed by Comparative Phosphoproteomic Signatures

Integrin α₄β_7, a CD4 independent receptor of human immunodeficiency virus-1 (HIV-1) gp120, defines a subset of CD4⁺T cells preferentially targeted by HIV. It is also considered as a promising therapeutic target for HIV-1 infection. Despite its role in HIV acquisition and disease progression, HIV-1-mediated integrin α₄β₇ signaling has not been elucidated so far. In view of this, we determined phosphoproteomic signatures of HIV-1 gp120 signaling as well as signaling mediated by the integrin α₄β₇ ligand, mucosal vascular addressin cell adhesion molecule-1 (MAdCAM-1), in primary CD4⁺ T cells. This is the first comprehensive report on MAdCAM-1 signaling, which is believed to enhance HIV-1 replication. Importantly, we identified proteins associated with both classical and nonclassical integrin functions. We observed that HIV-1 gp120 signaling is associated with proteins that have previously not been associated with HIV-1 pathogenesis and thus, need to be explored further. There was a significant overlap in proteins identified by both MAdCAM-1 and HIV-1 gp120 signaling, which most likely represents cellular processes triggered upon interaction of HIV-1 gp120 with integrin α₄β_7. Pathway analysis revealed enrichment of processes that could facilitate viral replication as well as viral entry through endocytosis. Although these results warrant independent replication and further validation, they suggest the presence of additional potential therapeutic targets. These results also suggest that combinatorial approaches for targeting both HIV-1 gp120 and MAdCAM-1 signaling may be necessary for efficient control of HIV-1 infection as well as novel innovation strategies in HIV therapeutics.

The WNK signaling pathway and salt-sensitive hypertension

The distal nephron of the kidney has a central role in sodium and fluid homeostasis, and disruption of this homeostasis due to mutations of with-no-lysine kinase 1 (WNK1), WNK4, Kelch-like 3 (KLHL3), or Cullin 3 (CUL3) causes pseudohypoaldosteronism type II (PHAII), an inherited hypertensive disease. WNK1 and WNK4 activate the NaCl cotransporter (NCC) at the distal convoluted tubule through oxidative stress-responsive gene 1 (OSR1)/Ste20-related proline-alanine-rich kinase (SPAK), constituting the WNK-OSR1/SPAK-NCC phosphorylation cascade. The level of WNK protein is regulated through degradation by the CUL3-KLHL3 E3 ligase complex. In the normal state, the activity of WNK signaling in the kidney is physiologically regulated by sodium intake to maintain sodium homeostasis in the body. In patients with PHAII, however, because of the defective degradation of WNK kinases, NCC is constitutively active and not properly suppressed by a high salt diet, leading to abnormally increased salt reabsorption and salt-sensitive hypertension. Importantly, recent studies have demonstrated that potassium intake, insulin, and TNFα are also physiological regulators of WNK signaling, suggesting that they contribute to the salt-sensitive hypertension associated with a low potassium diet, metabolic syndrome, and chronic kidney disease, respectively. Moreover, emerging evidence suggests that WNK signaling also has some unique roles in metabolic, cardiovascular, and immunological organs. Here, we review the recent literature and discuss the molecular mechanisms of the WNK signaling pathway and its potential as a therapeutic target.

Chemokines and other mediators in the development and functional organization of lymph nodes

Secondary lymphoid organs like lymph nodes (LNs) are the main inductive sites for adaptive immune responses. Lymphocytes are constantly entering LNs, scanning the environment for their cognate antigen and get replenished by incoming cells after a certain period of time. As only a minor percentage of lymphocytes recognizes cognate antigen, this mechanism of permanent recirculation ensures fast and effective immune responses when necessary. Thus, homing, positioning, and activation as well as egress require precise regulation within LNs. In this review we discuss the mediators, including chemokines, cytokines, growth factors, and others that are involved in the formation of the LN anlage and subsequent functional organization of LNs. We highlight very recent findings in the fields of LN development, steady-state migration in LNs, and the intranodal processes during an adaptive immune response.

Regulation of global CD8+ T-cell positioning by the actomyosin cytoskeleton

CD8⁺ T cells have evolved as one of the most motile mammalian cell types, designed to continuously scan peptide-major histocompatibility complexes class I on the surfaces of other cells. Chemoattractants and adhesion molecules direct CD8⁺ T-cell homing to and migration within secondary lymphoid organs, where these cells colocalize with antigen-presenting dendritic cells in confined tissue volumes. CD8⁺ T-cell activation induces a switch to infiltration of non-lymphoid tissue (NLT), which differ in their topology and biophysical properties from lymphoid tissue. Here, we provide a short overview on regulation of organism-wide trafficking patterns during naive T-cell recirculation and their switch to non-lymphoid tissue homing during activation. The migratory lifestyle of CD8⁺ T cells is regulated by their actomyosin cytoskeleton, which translates chemical signals from surface receptors into mechanical work. We explore how properties of the actomyosin cytoskeleton and its regulators affect CD8⁺ T cell function in lymphoid and non-lymphoid tissue, combining recent findings in the field of cell migration and actin network regulation with tissue anatomy. Finally, we hypothesize that under certain conditions, intrinsic regulation of actomyosin dynamics may render NLT CD8⁺ T-cell populations less dependent on input from extrinsic signals during tissue scanning.

WNK1-OSR1/SPAK KINASE CASCADE IS IMPORTANT FOR ANGIOGENESIS

WNK [with-no-lysine (K)] kinases are a family of four members of serine and threonine kinases that regulate renal Na+ and K+ transport. Mutations of WNK1 and WNK4 cause a hereditary hypertensive and hyperkalemic disease known as pseudohypoaldosteronism type II (PHA2). Unlike other WNK isoforms, WNK1 is ubiquitously expressed and regulates many other cellular processes outside the kidney. Oxidative stress response kinase (OSR1) and related STE 20/SPS1-related proline alanine-rich kinase (SPAK) are downstream kinases of WNK kinases. To examine the role of WNK kinase cascade in vivo, we generated global Wnk1-deleted mice and found that Wnk1-ablated mice die in utero from embryonic angiogenesis and cardiac developmental defects. Endothelial-specific Wnk1 deletion reveals that angiogenesis defect is due to WNK1 requirement in endothelium. We further showed that global and endothelial-deletion of Osr1 phenocopies Wnk1 deletion. Furthermore, expression of a catalytic constitutively active Osr1 transgene rescues angiogenesis defects and embryonic lethality of Wnk1-ablated mice. In zebrafish, Wnk1 knockdown causes similar angiogenesis defects to Vegf2 (Flk1) knockdown and that expression of WNK1 partially rescues Flk1 angiogenesis defects. The results indicate that WNK1 is downstream of VEGF signaling cascade. T-lymphocytes isolated from Wnk1-null mice exhibit migration defects. Inhibition of WNK1-OSR1 downstream target Na-K-2Cl cotransporter NKCC1 mimics migration defect of WNK1-deficient T-lymphocytes. Thus, WNK1-OSR1/SPAK cascade is important for angiogenesis. Regulation of ion homeostasis and cell volume may underlie the mechanism for WNK1 regulation of endothelial cell migration and angiogenesis.

Genetic and clinical predictors of CD4 lymphocyte recovery during suppressive antiretroviral therapy: Whole exome sequencing and antiretroviral therapy response phenotypes

Increase of peripheral blood CD4 lymphocyte counts is a key goal of combined antiretroviral therapy (cART); most, but not all, recipients respond adequately and promptly. A small number of studies have examined specific genetic factors associated with the extent of CD4 recovery. We report a genome-wide examination of factors that predict CD4 recovery in HIV-infected women. We identified women in in a cohort study who were on cART with viral load below 400 copies, and drew racially and ethnically matched samples of those with good CD4 response over 2 years or poor response. We analyzed the exomes of those women employing next generation sequencing for genes associated with CD4 recovery after controlling for non-genetic factors identified through forward stepwise selection as important. We studied 48 women with good CD4 recovery and 42 with poor CD4 recovery during virologically-suppressive cART. Stepwise logistic regression selected only age as a statistically significant (p<0.05) non-genetic predictor of response type (each additional year of age reduced the odds of good recovery by 11% (OR = 0.89, CI = 0.84–0.96, p = 0.0009). After adjustment for age and genomic estimates of race and ethnicity, 41 genes harbored variations associated with CD4 recovery group (p≤0.001); 5 of these have been previously reported to be associated with HIV infection, 4 genes would likely influence CD4 homeostasis, and 13 genes either had known functions or were members of product families that had functions for which interactions with HIV or effects on lymphocyte homeostasis were biologically plausible. Greater age was the strongest acquired factor that predicted poor CD4 cell recovery. Sequence variations spanning 41 genes were independently predictive of CD4 recovery. Many of these genes have functions that impact the cell cycle, apoptosis, lymphocyte migration, or have known interactions with HIV. These findings may help inform new hypotheses related to responses to HIV therapy and CD4 lymphocyte homeostasis.

Contribution of the WNK1 kinase to corneal wound healing using the tissue-engineered human cornea as an in vitro model

Damage to the corneal epithelium triggers important changes in the extracellular matrix (ECM) to which basal human corneal epithelial cells (hCECs) attach. These changes are perceived by integrin receptors that activate different intracellular signalling pathways, ultimately leading to re-epithelialization of the injured epithelium. In this study, we investigated the impact of pharmacological inhibition of specific signal transduction mediators on corneal wound healing using both monolayers of hCECs and the human tissue-engineered cornea (hTEC) as an in vitro 3D model. RNA and proteins were isolated from the wounded and unwounded hTECs to conduct gene profiling analyses and protein kinase arrays. The impact of WNK1 inhibition was evaluated on the wounded hTECs as well as on hCECs monolayers using a scratch wound assay. Gene profiling and protein kinase arrays revealed that expression and activity of several mediators from the integrin-dependent signaling pathways were altered in response to the ECM changes occurring during corneal wound healing. Phosphorylation of the WNK1 kinase turned out to be the most striking activation event going on during this process. The inhibition of WNK1 by WNK463 reduced the rate of corneal wound closure in both the hTEC and hCECs grown in monolayer compared with their respective negative controls. WNK463 also reduced phosphorylation of the WNK1 downstream targets SPAK/OSR1 in wounded hTECs. These in vitro results allowed for a better understanding of the cellular and molecular mechanisms involved in corneal wound healing and identified WNK1 as a kinase important to ensure proper wound healing of the cornea.

Cell volume regulation in cancer cell migration driven by osmotic water flow

Cancer metastasis is the most frequent cause of death for patients with cancer. The main current treatment for cancer metastasis is chemotherapy targeting cancer cells’ ability to proliferate. However, some types of cancer cells show resistance to chemotherapy. Recently, cancer cell migration has become the subject of interest as a novel target of cancer therapy. Cell migration requires many factors, such as the cytoskeleton, cell‐matrix adhesion and cell volume regulation. Here, we focus on cell volume regulation and the role of ion/water transport systems in cell migration. Transport proteins, such as ion channels, ion carriers, and aquaporins, are indispensable for cell volume regulation under steady‐state conditions and during exposure to osmotic stress. Studies from the last ~25 years have revealed that cell volume regulation also plays an important role in the process of cell migration. Water flow in accordance with localized osmotic gradients generated by ion transport contributes to the driving force for cell migration. Moreover, it has been reported that metastatic cancer cells have higher expression of these transport proteins than nonmetastatic cancer cells. Thus, ion/water transport proteins involved in cell volume regulation and cell migration could be novel therapeutic targets for cancer metastasis. In this review, after presenting the importance of ion/water transport systems in cell volume regulation, we discuss the roles of transport proteins in a pathophysiological context, especially in the context of cancer cell migration.

Oxidative burst and Dectin-1-triggered phagocytosis affected by norepinephrine and endocannabinoids: implications for fungal clearance under stress

A prolonged stress burden is known to hamper the efficiency of both the innate and the adaptive immune systems and to attenuate the stress responses by the catecholaminergic and endocannabinoid (EC) systems. Key mechanisms of innate immunity are the eradication of pathogens through phagocytosis and the respiratory burst. We tested the concentration-dependent, spontaneous and stimulated (via TNFα and N-formylmethionine-leucyl-phenylalanine) release of reactive oxygen species (ROS) by human polymorphonuclear leukocytes (PMNs) in vitro in response to norepinephrine (NE) and AM1241, a pharmacological ligand for the EC receptor CB2. We evaluated phagocytosis of Dectin-1 ligating zymosan particles and tested the cytokine response against Candida antigen in an in vitro cytokine release assay. Increasing concentrations of NE did not affect phagocytosis, yet stimulated ROS release was attenuated gradually reaching maximum suppression at 500 nM. Adrenergic receptor (AR) mechanisms using non-AR-selective (labetalol) as well as specific α-(prazosin) and β-(propranolol) receptor antagonists were tested. Results show that only labetalol and propranolol were able to recuperate cytotoxicity in the presence of NE, evidencing a β-receptor-mediated effect. The CB2 agonist, AM1241, inhibited phagocytosis at 10 µM and spontaneous peroxide release by PMNs. Use of the inverse CB2 receptor agonist SR144528 led to partial recuperation of ROS production, confirming the functional role of CB2. Additionally, AM1241 delayed early activation of monocytes and induced suppression of IL-2 and IL-6 levels in response to Candida via lower activity of mammalian target of rapamycin (mTOR). These findings provide new insights into key mechanisms of innate immunity under stressful conditions where ligands to the sympatho-adrenergic and EC system are released.

Mother-child histocompatibility and risk of rheumatoid arthritis and systemic lupus erythematosus among mothers

The study objective was to test the hypothesis that having histocompatible children increases the risk of rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE), possibly by contributing to the persistence of fetal cells acquired during pregnancy. We conducted a case control study using data from the UC San Francisco Mother Child Immunogenetic Study and studies at the Inova Translational Medicine Institute. We imputed human leukocyte antigen (HLA) alleles and minor histocompatibility antigens (mHags). We created a variable of exposure to histocompatible children. We estimated an average sequence similarity matching (SSM) score for each mother based on discordant mother-child alleles as a measure of histocompatibility. We used logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals. A total of 138 RA, 117 SLE, and 913 control mothers were analyzed. Increased risk of RA was associated with having any child compatible at HLA-B (OR 1.9; 1.2-3.1), DPB1 (OR 1.8; 1.2-2.6) or DQB1 (OR 1.8; 1.2-2.7). Compatibility at mHag ZAPHIR was associated with reduced risk of SLE among mothers carrying the HLA-restriction allele B*07:02 (n = 262; OR 0.4; 0.2-0.8). Our findings support the hypothesis that mother-child histocompatibility is associated with risk of RA and SLE.

Pleiotropic Action of Novel Bruton's Tyrosine Kinase Inhibitor BGB-3111 in Mantle Cell Lymphoma

Bruton's tyrosine kinase (BTK) is a key mediator of BCR-dependent cell growth signaling and a clinically effective therapeutic target in mantle cell lymphoma (MCL). The molecular impact of BTK inhibition remains unclear particularly in hematopoietic malignancies. We analyzed the molecular mechanisms of BTK inhibition with the novel inhibitor BGB-3111 (zanubrutinib) in MCL models. The efficacy of BGB-3111 was investigated using growth proliferation/cell viability and apoptosis assays in MCL cell lines and patient-derived xenograft (PDX) MCL cells. The activity and mechanisms of BGB-3111 were further confirmed using a cell line xenograft model, an MCL PDX mouse model, and a human phosphokinase profiler array and reverse phase protein array. Finally, the mechanisms related to resistance to BTK inhibition were analyzed by creating cell lines with low levels of BTK using CRISPR/Cas 9 genome editing. We found that inhibition of BTK leads to suppression of tumor growth, which was mediated via potent suppression of AKT/mTOR, apoptosis, and metabolic stress. Moreover, targeted disruption of the BTK gene in MCL cells resulted in resistance to BTK inhibition and the emergence of novel survival mechanisms. Our studies suggest a general efficacy of BTK inhibition in MCL and potential drug resistance mechanism via alternative signaling pathways.

WNK lysine deficient protein kinase 1 regulates human endometrial stromal cell decidualization, proliferation, and migration in part through mitogen-activated protein kinase 7

The differentiation of endometrial stromal cells into decidual cells, termed decidualization, is an integral step in the establishment of pregnancy. The mitogen-activated protein kinase homolog, WNK lysine deficient protein kinase 1 (WNK1), is activated downstream of epidermal growth factor receptor during decidualization. Primary human endometrial stromal cells (HESCs) were subjected to small interfering RNA knockdown of WNK1 followed by in vitro decidualization. This abrogated expression of the decidual marker genes, insulin like growth factor binding protein 1 (IGFBP1) and prolactin (PRL), and prevented adoption of decidual cell morphology. Analysis of the WNK1-dependent transcriptome by RNA-Seq demonstrated that WNK1 regulates the expression of 1858 genes during decidualization. Gene ontology and upstream regulator pathway analysis showed that WNK1 regulates cell migration, differentiation, and proliferation. WNK1 was required for many of the gene expression changes that drive decidualization, including the induction of the inflammatory cytokines, C-C motif chemokine ligand 8 (CCL8), interleukin 1 beta (IL1B), and interleukin 15 (IL15), and the repression of transforming growth factor-beta (TGF-beta) pathway genes, including early growth response 2 (EGR2), SMAD family member 3 (SMAD3), integrin subunit alpha 2 (ITGA2), integrin subunit alpha 4 (ITGA4), and integrin subunit beta 3 (ITGB3). In addition to abrogating decidualization, WNK1 knockdown decreased the migration and proliferation of HESCs. Furthermore, mitogen-activated protein kinase 7 (MAPK7), a known downstream target of WNK1, was activated during decidualization in a WNK1-dependent manner. Small interfering RNA knockdown of MAPK7 demonstrated that MAPK7 regulates a subset of WNK1-regulated genes and controls the migration and proliferation of HESCs. These results indicate that WNK1 and MAPK7 promote migration and proliferation during decidualization and regulate the expression of inflammatory cytokines and TGF-beta pathway genes in HESCs.

WNK1 regulates skeletal muscle cell hypertrophy by modulating the nuclear localization and transcriptional activity of FOXO4

With-no-lysine (K) (WNK) kinases, which are mutated in the inherited form of hypertension pseudohypoaldosteronism type II, are essential regulators of membrane ion transporters. Here, we report that WNK1 positively regulates skeletal muscle cell hypertrophy via mediating the function of the pro-longevity transcription factor forkhead box protein O4 (FOXO4) independent of the conventional WNK signaling pathway linking SPS/STE20-related proline-alanine–rich kinase (SPAK)/oxidative stress response kinase 1 (OSR1) to downstream effector ion transporters. Small interfering RNA (siRNA)-mediated silencing of WNK1, but not SPAK/OSR1 kinases, induced myotube atrophy and remarkable increases in the mRNA expression of the muscle atrophy ubiquitin ligases MAFbx and MuRF1 in C2C12 mouse skeletal muscle cells. WNK1 silencing also increased FOXO4 nuclear localization, and co-transfection of Foxo4-targeted siRNA completely reversed the myotube atrophy and upregulation of atrogene transcription induced by WNK1 silencing. We further illustrated that WNK1 protein abundance in skeletal muscle was increased by chronic voluntary wheel running exercise (hypertrophic stimulus) and markedly decreased by adenine-induced chronic kidney disease (atrophic stimulus) in mice. These findings suggest that WNK1 is involved in the physiological regulation of mammalian skeletal muscle hypertrophy and atrophy via interactions with FOXO4. The WNK1-FOXO4 axis may be a potential therapeutic target in human diseases causing sarcopenia.

T-Cell Immunopeptidomes Reveal Cell Subtype Surface Markers Derived From Intracellular Proteins

Immunopeptidomes promise novel surface markers as ideal immunotherapy targets, but their characterization by mass spectrometry (MS) remains challenging. Until recently, cell numbers exceeding 10⁹ were needed to survey thousands of HLA ligands. Such limited analytical sensitivity has historically constrained the types of clinical specimens that can be evaluated to cell cultures or bulk tissues. Measuring immunopeptidomes from purified cell subpopulations would be preferable for many applications, particularly those evaluating rare, primary hematopoietic cell lineages. Here, we test the feasibility of immunopeptidome profiling from limited numbers of primary purified human regulatory T cells (T_Reg ), conventional T cells (T_conv ), and activated T cells. The combined T cell immunopeptide dataset reported here contains 13 804 unique HLA ligands derived from 5049 proteins. Of these, more than 700 HLA ligands were derived from 82 proteins that we exclusively identified from T_Reg -enriched cells. This study 1) demonstrates that primary, lineage-enriched T cell subpopulations recovered from single donors are compatible with immunopeptidome analysis; 2) presents new T_Reg -biased ligand candidates; and 3) supports immunopeptidome surveys' value for revealing T cell biology that may not be apparent from expression data alone. Taken together, these findings open up new avenues for targeting T_Reg and abrogating their suppressive functions to treat cancer.

Epstein-Barr Virus (EBV) Latent Protein EBNA3A Directly Targets and Silences the STK39 Gene in B Cells Infected by EBV

Epstein-Barr virus (EBV) establishes latent infection in human B cells and is associated with a wide range of cancers. The EBV nuclear antigen 3 (EBNA3) family proteins are critical for B cell transformation and function as transcriptional regulators. It is well established that EBNA3A and EBNA3C cooperate in the regulation of cellular genes. Here, we demonstrate that the gene STK39 is repressed only by EBNA3A. This is the first example of a gene regulated only by EBNA3A in EBV-transformed lymphoblastoid cell lines (LCLs) without the help of EBNA3C. This was demonstrated using a variety of LCLs carrying either knockout, revertant, or conditional EBNA3 recombinants. Investigating the kinetics of EBNA3A-mediated changes in STK39 expression showed that STK39 becomes derepressed quickly after EBNA3A inactivation. This derepression is reversible as EBNA3A reactivation represses STK39 in the same cells expressing a conditional EBNA3A. STK39 is silenced shortly after primary B cell infection by EBV, and no STK39-encoded protein (SPAK) is detected 3 weeks postinfection. Chromatin immunoprecipitation (ChIP) analysis indicates that EBNA3A directly binds to a regulatory region downstream of the STK39 transcription start site. For the first time, we demonstrated that the polycomb repressive complex 2 with the deposition of the repressive mark H3K27me3 is not only important for the maintenance of an EBNA3A target gene (STK39) but is also essential for the initial establishment of its silencing. Finally, we showed that DNA methyltransferases are involved in the EBNA3A-mediated repression of STK39.

IMPORTANCE EBV is well known for its ability to transform B lymphocytes to continuously proliferating lymphoblastoid cell lines. This is achieved in part by the reprogramming of cellular gene transcription by EBV transcription factors, including the EBNA3 proteins that play a crucial role in this process. In the present study, we found that EBNA3A epigenetically silences STK39. This is the first gene where EBNA3A has been found to exert its repressive role by itself, without needing its coregulators EBNA3B and EBNA3C. Furthermore, we demonstrated that the polycomb repressor complex is essential for EBNA3A-mediated repression of STK39. Findings in this study provide new insights into the regulation of cellular genes by the transcription factor EBNA3A.

A salt-sensing kinase in T lymphocytes, SGK1, drives hypertension and hypertensive end-organ damage

We previously showed that angiotensin II (Ang II) increases T cell production of IL-17A, and that mice deficient in IL-17A have blunted hypertension and attenuated renal and vascular dysfunction. It was recently shown that salt enhances IL-17A production from CD4+ T cells via a serum- and glucocorticoid-regulated kinase 1-dependent (SGK1-dependent) pathway. Thus, we tested the hypothesis that SGK1 signaling in T cells promotes hypertension and contributes to end-organ damage. We show that loss of T cell SGK1 results in a blunted hypertensive response to Ang II infusion by 25 mmHg. Importantly, renal and vascular inflammation is abrogated in these mice compared with control mice. Furthermore, mice lacking T cell SGK1 are protected from Ang II-induced endothelial dysfunction and renal injury. Loss of T cell SGK1 also blunts blood pressure and vascular inflammation in response to deoxycorticosterone acetate-salt (DOCA-salt) hypertension. Finally, we demonstrate that the Na+-K+-2Cl- cotransporter 1 (NKCC1) is upregulated in Th17 cells and is necessary for the salt-induced increase in SGK1 and the IL-23 receptor. These studies demonstrate that T cell SGK1 and NKCC1 may be novel therapeutic targets for the treatment of hypertension and identify a potentially new mechanism by which salt contributes to hypertension.

WNK Kinase Signaling in Ion Homeostasis and Human Disease

WNK kinases, along with their upstream regulators (CUL3/KLHL3) and downstream targets (the SPAK/OSR1 kinases and the cation-Cl^- cotransporters [CCCs]), comprise a signaling cascade essential for ion homeostasis in the kidney and nervous system. Recent work has furthered our understanding of the WNKs in epithelial transport, cell volume homeostasis, and GABA signaling, and uncovered novel roles for this pathway in immune cell function and cell proliferation.

WNK Kinases in Development and Disease

WNK (With-No-Lysine (K)) kinases are serine-threonine kinases characterized by an atypical placement of a catalytic lysine within the kinase domain. Mutations in human WNK1 or WNK4 cause an autosomal dominant syndrome of hypertension and hyperkalemia, reflecting the fact that WNK kinases are critical regulators of renal ion transport processes. Here, the role of WNKs in the regulation of ion transport processes in vertebrate and invertebrate renal function, cellular and organismal osmoregulation, and cell migration and cerebral edema will be reviewed, along with emerging literature demonstrating roles for WNKs in cardiovascular and neural development, Wnt signaling, and cancer. Conserved roles for these kinases across phyla are emphasized.