Muscle LIM protein of Macrobrachium nipponense (MnMLP) involved in immune and stress response.

The muscle LIM protein (MLP) is a member of the cysteine and glycine-rich protein (CSRP) family, composed of CSRP1, CSRP2 and CSRP3/MLP. MLP is involved in a multitude of functional roles, including cytoskeletal organization, transcriptional regulation, and signal transduction. However, the molecular mechanisms underlying its involvement in immune and stress responses remain to be elucidated. This study identified an MnMLP in the freshwater crustacean Macrobrachium nipponense. The isothermal titration calorimetry assay demonstrated that recombinant MnMLP was capable of coordinating with Zn2+. Upon challenge by Aeromonas veronii or WSSV, and exposure to CdCl2, up-regulation was recorded in the muscle and intestinal tissues, suggesting its involvement in immune and anti-stress responses. MnMLP protein was predominantly expressed in the cytoplasm of the transfected HEK-293T cells, but after treatment with LPS, Cd2+ or H2O2, the MnMLP was observed to be transferred into the nucleus. The comet assay demonstrated that the overexpression of MnMLP could mitigate the DNA damage induced by H2O2 in HEK-293T cells, suggesting the potential involvement of MnMLP in the DNA repair process. These findings suggest that DNA repair may represent a possible mechanism by which MnMLP may be involved in the host's defense against pathogens and stress.

NSUN5 Facilitates Viral RNA Recognition by RIG-I Receptor.

The RIG-I receptor induces the innate antiviral responses upon sensing RNA viruses. The mechanisms through which RIG-I optimizes the strength of the downstream signaling remain incompletely understood. In this study, we identified that NSUN5 could potentiate the RIG-I innate signaling pathway. Deficiency of NSUN5 enhanced RNA virus proliferation and inhibited the induction of the downstream antiviral genes. Consistently, NSUN5-deficient mice were more susceptible to RNA virus infection than their wild-type littermates. Mechanistically, NSUN5 bound directly to both viral RNA and RIG-I, synergizing the recognition of dsRNA by RIG-I. Collectively, to our knowledge, this study characterized NSUN5 as a novel RIG-I coreceptor, playing a vital role in restricting RNA virus infection.

Myasthenia gravis AChR antibodies inhibit function of rapsyn-clustered AChRs.

OBJECTIVE: Direct inhibition of acetylcholine receptor (AChR) function by autoantibodies (Abs) is considered a rare pathogenic mechanism in myasthenia gravis (MG), but is usually studied on AChRs expressed in cell lines, rather than tightly clustered by the intracellular scaffolding protein, rapsyn, as at the intact neuromuscular junction. We hypothesised that clustered AChRs would provide a better target for investigating the functional effects of AChR-Abs. METHODS: Acetylcholine-induced currents were measured using whole-cell patch clamping and a fast perfusion system to assess fast (<2 min) functional effects of the serum samples. The sensitivity, specificity and rapidity of the system were first demonstrated by applying maternal AChR-Ab positive plasmas known to inhibit fetal AChR function in TE671 cells. Eleven previously untested AChR-Ab positive MG sera, 10 AChR-Ab negative MG sera and 5 healthy control sera were then applied to unclustered and rapsyn-clustered human adult AChRs in CN21 cells. RESULTS: The maternal AChR-Ab positive plasmas reduced fetal AChR currents, but not adult AChR currents, by >80% within 100 s. Only 2/11 AChR-Ab positive sera inhibited AChR currents in unclustered AChRs, but 6/11 AChR-Ab positive sera compared with none of the 10 AChR-Ab negative sera (p=0.0020) inhibited rapsyn-clustered AChR currents, and current inhibition by the AChR-Ab positive sera was greater when the AChRs were clustered (p=0.0385). None of the sera had detectable effects on desensitisation or recovery from desensitisation. CONCLUSION: These results show that antibodies can inhibit AChR function rapidly and demonstrate the importance of clustering in exploring pathogenic disease mechanisms of MG Abs.

Shigella hijacks the glomulin-cIAPs-inflammasome axis to promote inflammation.

Shigella deploys a unique mechanism to manipulate macrophage pyroptosis by delivering the IpaH7.8 E3 ubiquitin ligase via its type III secretion system. IpaH7.8 ubiquitinates glomulin (GLMN) and elicits its degradation, thereby inducing inflammasome activation and pyroptotic cell death of macrophages. Here, we show that GLMN specifically binds cellular inhibitor of apoptosis proteins 1 and 2 (cIAP1 and cIAP2), members of the inhibitor of apoptosis (IAP) family of RING-E3 ligases, which results in reduced E3 ligase activity, and consequently inflammasome-mediated death of macrophages. Importantly, reducing the levels of GLMN in macrophages via IpaH7.8, or siRNA-mediated knockdown, enhances inflammasome activation in response to infection by Shigella, Salmonella, or Pseudomonas, stimulation with NLRP3 inflammasome activators (including SiO2, alum, or MSU), or stimulation of the AIM2 inflammasome by poly dA:dT GLMN binds specifically to the RING domain of both cIAPs, which inhibits their self-ubiquitination activity. These findings suggest that GLMN is a negative regulator of cIAP-mediated inflammasome activation, and highlight a unique Shigella stratagem to kill macrophages, promoting severe inflammation.

Myoferlin-Mediated Lysosomal Exocytosis Regulates Cytotoxicity by Phagocytes.

During inflammation, phagocytes release digestive enzymes from lysosomes to degrade harmful cells such as pathogens and tumor cells. However, the molecular mechanisms regulating this process are poorly understood. In this study, we identified myoferlin as a critical regulator of lysosomal exocytosis by mouse phagocytes. Myoferlin is a type II transmembrane protein with seven C2 domains in the cytoplasmic region. It localizes to lysosomes and mediates their fusion with the plasma membrane upon calcium stimulation. Myoferlin promotes the release of lysosomal contents, including hydrolytic enzymes, which increase cytotoxicity. These data demonstrate myoferlin's critical role in lysosomal exocytosis by phagocytes, providing novel insights into the mechanisms of inflammation-related cellular injuries.

Ankyrin repeat domain 1 regulates innate immune responses against herpes simplex virus 1: A potential role in eczema herpeticum.

BACKGROUND: Atopic dermatitis (AD) is a common inflammatory skin disease. A subset of patients with AD are susceptible to disseminated herpes simplex virus (HSV) infection, a complication termed eczema herpeticum (ADEH+). The immune mechanisms causing ADEH+ remain elusive. Using RNA sequencing, we recently found that ankyrin repeat domain 1 (ANKRD1) was significantly induced in human PBMCs upon HSV-1 stimulation, and its induction in patients with ADEH+ was significantly reduced compared with that seen in AD patients without a history of eczema herpeticum (ADEH-). OBJECTIVE: We sought to validate ANKRD1 gene expression in nonatopic (NA) subjects, patients with ADEH-, and patients with ADEH+ and to delineate the biological function of ANKRD1 and the signaling pathway or pathways involved. METHODS: Purification of human PBMCs, monocytes, B cells, dendritic cells, T cells, and natural killer cells; RNA extraction and quantitative RT-PCR; small interfering RNA technique; co-immunoprecipitation; and Western blot assays were used. RESULTS: ANKRD1 expression was significantly reduced in PBMCs from patients with ADEH+ after HSV-1 stimulation compared with PBMCs from patients with ADEH-. We found that the induction of ANKRD1 by HSV-1 and multiple pattern recognition receptor agonists are mediated by inflammatory cytokines. Silencing ANKRD1 gene expression in antigen-presenting cells led to increased viral load and reduced IFNB1 and IL29 production. Using co-immunoprecipitation methods, we demonstrated that ANKRD1 formed protein complexes with interferon regulatory factor (IRF) 3 and IRF7, which are important transcription factors regulating signaling transduction of pattern recognition receptors. Overexpression of ANKRD1 enhanced the IRF3-mediated signaling pathways. CONCLUSION: ANKRD1 is involved in IRF3-mediated antiviral innate immune signaling pathways. Its reduced expression in patients with ADEH+ might contribute to the pathogenesis of ADEH+.

HER2-Specific Targeted Toxin DARPin-LoPE: Immunogenicity and Antitumor Effect on Intraperitoneal Ovarian Cancer Xenograft Model.

High immunogenicity and systemic toxicity are the main obstacles limiting the clinical use of the therapeutic agents based on Pseudomonas aeruginosa exotoxin A. In this work, we studied the immunogenicity, general toxicity and antitumor effect of the targeted toxin DARPin-LoPE composed of HER2-specific DARPin and a low immunogenic exotoxin A fragment lacking immunodominant human B lymphocyte epitopes. The targeted toxin has been shown to effectively inhibit the growth of HER2-positive human ovarian carcinoma xenografts, while exhibiting low non-specific toxicity and side effects, such as vascular leak syndrome and liver tissue degradation, as well as low immunogenicity, as was shown by specific antibody titer. This represents prospects for its use as an agent for targeted therapy of HER2-positive tumors.

BCL2L12 improves risk stratification and prediction of BFM-chemotherapy response in childhood acute lymphoblastic leukemia.

Background Risk-adjusted treatment has led to outstanding improvements of the remission and survival rates of childhood acute lymphoblastic leukemia (ALL). Nevertheless, overtreatment-related toxicity and resistance to therapy have not been fully prevented. In the present study, we evaluated for the first time the clinical impact of the apoptosis-related BCL2L12 gene in prognosis and risk stratification of BFM-treated childhood ALL. Methods Bone marrow specimens were obtained from childhood ALL patients upon disease diagnosis and the end-of-induction (EoI; day 33) of the BFM protocol, as well as from control children. Following total RNA extraction and reverse transcription, BCL2L12 expression levels were determined by qPCR. Patients' cytogenetics, immunophenotyping and minimal residual disease (MRD) evaluation were performed according to the international guidelines. Results BCL2L12 expression was significantly increased in childhood ALL and correlated with higher BCL2/BAX expression ratio and favorable disease markers. More importantly, BCL2L12 expression was associated with disease remission, while the reduced BCL2L12 expression was able to predict patients' poor response to BFM therapy, in terms of M2-M3 response and MRD≥0.1% on day 15. The survival analysis confirmed the significantly higher risk of the BFM-treated patients underexpressing BCL2L12 at disease diagnosis for early relapse and worse survival. Lastly, evaluation of BCL2L12 expression clearly strengthened the prognostic value of the established disease prognostic markers, leading to superior prediction of patients' outcome and improved specificity of BFM risk stratification. Conclusions The expression levels of the apoptosis-related BCL2L12 predict response to treatment and survival outcome of childhood ALL patients receiving BFM chemotherapy.

Transcriptional profiles of type 2 diabetes in human skeletal muscle reveal insulin resistance, metabolic defects, apoptosis, and molecular signatures of immune activation in response to infections.

Skeletal muscle insulin resistance is considered to be the primary defect involved in type 2 diabetes mellitus (T2DM). Despite transcriptome studies in limited T2DM human subjects suggesting an association of T2DM with impaired oxidative phosphorylation in muscle, its molecular pathogenesis remains largely unknown. To identify dysregulated genes and gene networks that are associated with T2DM in human skeletal muscle, we examined expression patterns of 56,318 transcribed genes on 92 T2DM cases and 184 gender-, age- and race-matched non-diabetic controls from the Genotype-Tissue Expression (GTEx) database. RNA-Sequencing data suggest that diabetic skeletal muscle is characterized by decreased expression of genes that are related to insulin resistance (IRS2, MTOR, SLC2A4, and PPARA), carbohydrate, energy, and amino acid metabolism pathways (NDUFS1, NDUFA10, NDUFB4, NDUFB5, NDUFA5, NDUFB10, SDHB, SDHC, ATP5H, ATP5A, and ATP5J). Up-regulated genes in T2DM are mainly enriched in apoptosis pathways (TP53, GADD45A, TNFRSF10B, TP53AIP1, and PMAIP1), and notably include immune-related pathways suggestive of a response to various infectious diseases (C2, CFB, C4A, C4B, C1S, C1R, C3, HLA-DRA, HLA-DMA, HLA-DOA, and HLA-DPB1). These results confirm the essential regulation of impaired insulin signaling and oxidative phosphorylation in the muscle of T2DM patients, and provide novel molecular insights into the pathophysiological mechanisms of T2DM.

Tumor necrosis factor suppresses interleukin 10 in peripheral B cells via upregulating Bcl2-like protein 12 in patients with inflammatory bowel disease.

The pathogenesis of the immune regulation dysfunction is unclear. Bcl2-like protein 12 (Bcl2L12) has immune suppression function. This study tests a hypothesis that tumor necrosis factor (TNF) increases Bcl2L12 to suppress the expression of interleukin (IL) 10 in peripheral B cells of patients with inflammatory bowel disease (IBD). In this study, peripheral blood samples were collected from IBD patients and healthy controls. B cells were isolated from the blood samples. The expression of IL-10 and Bcl2L12 in B cells was analyzed by quantitative reverse transcription polymerase chain reaction and Western blotting. We observed that the expression of Bcl2L12 in the peripheral B cells was higher in IBD patients than that in healthy controls. The IL-10 levels in B cells were negatively correlated with the expression of Bcl2L12. Exposure of B cells to TNF in the culture enhanced the expression of Bcl2L12. The Bcl2L12 mediated the effects of TNF on suppression of IL-10 in B cells. In conclusion, Bcl2L12 mediates the effects of TNF to suppress the expression of IL-10 in B cells. The data suggest that Bcl2L12 may be a therapeutic target for the treatment of IBD.

The monocarboxylate transporter 4 is required for glycolytic reprogramming and inflammatory response in macrophages.

There has been fast growing evidence showing that glycolysis plays a critical role in the activation of immune cells. Enhanced glycolysis leads to increased formation of intracellular lactate that is exported to the extracellular environment by monocarboxylate transporter 4 (MCT4). Although the biological activities of extracellular lactate have been well studied, it is less understood how the lactate export is regulated or whether lactate export affects glycolysis during inflammatory activation. In this study, we found that MCT4 is up-regulated by TLR2 and TLR4, but not TLR3 agonists in a variety of macrophages. The increased expression of MCT4 was mediated by MYD88 in a NF-κB-dependent manner. Furthermore, we found that MCT4 is required for macrophage activation upon TLR2 and TLR4 stimulations, as evidenced by attenuated expression of proinflammatory mediators in macrophages with MCT4 knockdown. Mechanistically, we found that MCT4 knockdown leads to enhanced intracellular accumulation of lactate and decreased glycolysis in LPS-treated macrophages. We found that LPS-induced expression of key glycolytic enzymes hexokinase 2 and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 is diminished in macrophages with MCT4 knockdown. Our data suggest that MCT4 up-regulation represents a positive feedback mechanism in macrophages to maintain a high glycolytic rate that is essential to a fully activated inflammatory response.

LIM-only protein FHL2 regulates experimental pulmonary Schistosoma mansoni egg granuloma formation.

LIM-only protein FHL2 is associated with several immune and inflammatory diseases such as arthritis, influenza A virus infection, and lung inflammation. However, the role of FHL2 in macrophage differentiation and in the development of granuloma formation is unknown. Here, we show that expression of FHL2 is induced in mouse bone marrow derived macrophages (BMMs) following stimulation with M2 cytokines such as IL-4 and IL-10. FHL2-knockout (FHL2-KO) BMMs exhibit a proinflammatory M1 phenotype after LPS treatment and display a reduced anti-inflammatory M2 phenotype following IL-4 treatment. Furthermore, thioglycollate-induced migration of macrophages and B cells is enhanced in FHL2-KO mice. To evaluate the importance of FHL2 in the development of pulmonary granuloma formation, FHL2-KO mice were challenged with Schistosoma mansoni eggs. FHL2-KO mice show an enhanced number of granulomas and display decreased expression of Th2 markers and an exacerbated Th1 type of inflammation, characterized by enhanced expression of neutrophil markers and Th1 cytokines. Furthermore, the expression of barrier proteins is reduced in FHL2-KO lung compared to WT. Collectively, these data identify a previously unrecognized role for FHL2 in the pathogenesis of pulmonary granulomatous inflammation, partly through its effect on macrophage polarization, modulation of the Th1/Th2 balance and regulation of permeability in lung.

RCAN 1 and 3 proteins regulate thymic positive selection.

Cooperation between calcineurin (CN)-NFATc and RAF-MEK-ERK signaling pathways is essential in thymocyte positive selection. It is known that the Regulators of Calcineurin (RCAN) proteins can act either facilitating or suppressing CN-dependent signaling events. Here, we show that RCAN genes are expressed in lymphoid tissues, and address the role of RCAN proteins in T cell development. Overexpression of human RCAN3 and RCAN1 can modulate T cell development by increasing positive selection-related surface markers, as well as the "Erk(hi) competence state" in double positive thymocytes, a characteristic molecular signature of positive selection, without affecting CN activity. We also found that RCAN1/3 interact with RAF kinases and CN in a non-exclusive manner. Our data suggests that the balance of RCAN interactions with CN and/or RAF kinases may influence T cell positive selection.

'Medusa-head ataxia': the expanding spectrum of Purkinje cell antibodies in autoimmune cerebellar ataxia. Part 1: Anti-mGluR1, anti-Homer-3, anti-Sj/ITPR1 and anti-CARP VIII.

Serological testing for anti-neural autoantibodies is important in patients presenting with idiopathic cerebellar ataxia, since these autoantibodies may indicate cancer, determine treatment and predict prognosis. While some of them target nuclear antigens present in all or most CNS neurons (e.g. anti-Hu, anti-Ri), others more specifically target antigens present in the cytoplasm or plasma membrane of Purkinje cells (PC). In this series of articles, we provide a detailed review of the clinical and paraclinical features, oncological, therapeutic and prognostic implications, pathogenetic relevance, and differential laboratory diagnosis of the 12 most common PC autoantibodies (often referred to as 'Medusa-head antibodies' due to their characteristic somatodendritic binding pattern when tested by immunohistochemistry). To assist immunologists and neurologists in diagnosing these disorders, typical high-resolution immunohistochemical images of all 12 reactivities are presented, diagnostic pitfalls discussed and all currently available assays reviewed. Of note, most of these antibodies target antigens involved in the mGluR1/calcium pathway essential for PC function and survival. Many of the antigens also play a role in spinocerebellar ataxia. Part 1 focuses on anti-metabotropic glutamate receptor 1-, anti-Homer protein homolog 3-, anti-Sj/inositol 1,4,5-trisphosphate receptor- and anti-carbonic anhydrase-related protein VIII-associated autoimmune cerebellar ataxia (ACA); part 2 covers anti-protein kinase C gamma-, anti-glutamate receptor delta-2-, anti-Ca/RhoGTPase-activating protein 26- and anti-voltage-gated calcium channel-associated ACA; and part 3 reviews the current knowledge on anti-Tr/delta notch-like epidermal growth factor-related receptor-, anti-Nb/AP3B2-, anti-Yo/cerebellar degeneration-related protein 2- and Purkinje cell antibody 2-associated ACA, discusses differential diagnostic aspects and provides a summary and outlook.

Evaluation of the specificity of four commercially available antibodies to alpha-syntrophin.

Alpha-syntrophin (SNTA) is an adaptor protein that regulates several signaling pathways. To analyze expression of SNTA immunoblot assays must be performed. Here, the specificity of four commercially available SNTA antibodies has been evaluated in immunoblot experiments using liver tissues of wild-type and SNTA-deficient mice. While one of the antibodies reacts with SNTA, two antibodies specifically recognize beta 2 syntrophin (SNTB2). The antigen detected by the fourth antibody has not been identified but is different from SNTA and SNTB2. Therefore, only one of the four tested antibodies is appropriate to analyze SNTA protein levels by immunoblot.

A reverse Warburg metabolism in oral squamous cell carcinoma is not dependent upon myofibroblasts.

BACKGROUND: The reverse Warburg effect describes the phenomenon that epithelial cancer cells take advantage of the metabolic machinery from nearby cancer-associated fibroblast, inducing them to produce lactate and ketones to fuel the high metabolic demands of the epithelial tumour tissues. This is in breast cancer observed as a lack of stromal caveolin-1 (CAV-1) and an increased expression of monocarboxylate transporter 4 (MCT-4) in the tumour stroma, with a concomitant increase in the expression of monocarboxylate transporter 1 (MCT-1) in the epithelial, tumour compartment. The lack of CAV-1 and increased expression of MCT-4 have been shown to have prognostic importance, primarily in patients with breast cancer. However, this phenomenon has only scarcely been described in oral squamous cell carcinoma (OSCC). Given the prognostic importance of myofibroblasts in OSCC, we also examined a potential relationship between the expression of MCT-4 and the presence of myofibroblasts. METHODS: Paraffin-embedded tissues from 30 patients with OSCC were immunostained with antibodies towards MCT-1, MCT-4, Cav-1, GLUT-1, α-SMA, TOMM20 and KI-67, and evaluated for their specific epithelial and stromal expression. RESULTS AND CONCLUSIONS: In patients with OSCC, we find an increased expression of MCT-1 and MCT-4 in both the epithelial and stromal compartment, with almost no overlap in their spatial expression. We found a large spatial overlap between α-SMA and MCT-1 in the stroma compartment, but no relationship between MCT-4 and myofibroblasts. Interestingly, we did not observe any relationship between the absence of CAV-1 and the presence of MCT-4 as has been shown in breast carcinomas.

Anti-CarP antibodies in two large cohorts of patients with rheumatoid arthritis and their relationship to genetic risk factors, cigarette smoking and other autoantibodies.

INTRODUCTION: In rheumatoid arthritis (RA), several genetic risk factors and smoking are strongly associated with the presence of anticitrullinated protein antibodies (ACPA), while much less is known about risk factors for ACPA-negative RA. Antibodies against carbamylated proteins (anti-CarP) have been described in both ACPA-positive and ACPA-negative RA patients. In this study, we have analysed the relationships among anti-CarP antibodies, ACPA, genetic risk factors (HLA-DRB1 alleles and PTPN22) and smoking in RA. METHODS: Presence of antibodies to carbamylated fetal calf serum (CarP-FCS) and fibrinogen (CarP-Fib) was determined by inhouse ELISAs among RA cases in the Leiden Early Arthritis Clinic (n=846) and in the Swedish Epidemiological Investigation of Rheumatoid Arthritis (n=1985) cohorts. ORs for associations with different HLA-DRB1 alleles, PTPN22 genotypes and smoking were calculated separately for each cohort as well as in meta-analysis in RA subsets defined by the presence/absence of anti-CarP and anticyclic citrullinated peptide (anti-CCP) antibodies. RESULTS: In both cohorts, anti-CarP antibody positivity was mainly detected in the anti-CCP-positive population (49%-73%), but also in the anti-CCP-negative population (8%-14%). No associations between anti-CarP antibodies and HLA-DRB1 shared epitope alleles could be identified, while there were data to support an association between anti-CarP-FCS and HLA-DRB1*03. Further analyses did not reveal any specific associations of anti-CarP antibodies with other HLA-DRB1 alleles, PTPN22 genotypes or smoking. CONCLUSIONS: Anti-CarP antibodies were present in both ACPA-positive and ACPA-negative RA. There were no significant associations among anti-CarP antibodies and HLA-DRB1 alleles, PTPN22 or smoking. These data suggest that different biological mechanisms may underlie anti-CarP versus anti-CCP antibody formation.

Self-antigen recognition by follicular lymphoma B-cell receptors.

Follicular lymphoma is a monoclonal B-cell malignancy with each patient's tumor expressing a unique cell surface immunoglobulin (Ig), or B-cell receptor (BCR), that can potentially recognize antigens and/or transduce signals into the tumor cell. Here we evaluated the reactivity of tumor derived Igs for human tissue antigens. Self-reactivity was observed in 26% of tumor Igs (25 of 98). For one follicular lymphoma patient, the recognized self-antigen was identified as myoferlin. This patient's tumor cells bound recombinant myoferlin in proportion to their level of BCR expression, and the binding to myoferlin was preserved despite ongoing somatic hypermutation of Ig variable regions. Furthermore, BCR-mediated signaling was induced after culture of tumor cells with myoferlin. These results suggest that antigen stimulation may provide survival signals to tumor cells and that there is a selective pressure to preserve antigen recognition as the tumor evolves.

The kinase domains of obscurin interact with intercellular adhesion proteins.

Obscurins comprise a family of giant (~870- to 600-kDa) and small (~250- to 55-kDa) proteins that play important roles in myofibrillogenesis, cytoskeletal organization, and cell adhesion and are implicated in hypertrophic cardiomyopathy and tumorigenesis. Giant obscurins are composed of tandem structural and signaling motifs, including 2 serine/threonine kinase domains, SK1 and SK2, present at the COOH terminus of giant obscurin-B. Using biochemical and cellular approaches, we show for the first time that both SK1 and SK2 possess enzymatic activities and undergo autophosphorylation. SK2 can phosphorylate the cytoplasmic domain of N-cadherin, a major component of adherens junctions, and SK1 can interact with the extracellular domain of the ß1-subunit of the Na(+)/K(+)-ATPase, which also resides in adherens junctions. Immunostaining of nonpermeabilized myofibers and cardiocytes revealed that some obscurin kinase isoforms localize extracellularly. Quantification of the exofacial expression of obscurin kinase proteins indicated that they occupy ~16 and ~5% of the sarcolemmal surface in myofibers and cardiocytes, respectively. Treatment of heart lysates with peptide-N-glycosidase F revealed that while giant obscurin-B localizes intracellularly, possessing dual kinase activity, a small obscurin kinase isoform that contains SK1 localizes extracellularly, where it undergoes N-glycosylation. Collectively, our studies demonstrate that the obscurin kinase domains are enzymatically active and may be involved in the regulation of cell adhesion.

Lactate's impact on immune cells in sepsis: unraveling the complex interplay.

Lactate significantly impacts immune cell function in sepsis and septic shock, transcending its traditional view as just a metabolic byproduct. This review summarizes the role of lactate as a biomarker and its influence on immune cell dynamics, emphasizing its critical role in modulating immune responses during sepsis. Mechanistically, key lactate transporters like MCT1, MCT4, and the receptor GPR81 are crucial in mediating these effects. HIF-1α also plays a significant role in lactate-driven immune modulation. Additionally, lactate affects immune cell function through post-translational modifications such as lactylation, acetylation, and phosphorylation, which alter enzyme activities and protein functions. These interactions between lactate and immune cells are central to understanding sepsis-associated immune dysregulation, offering insights that can guide future research and improve therapeutic strategies to enhance patient outcomes.