Protein kinase CK2 is a critical regulator of epithelial homeostasis in chronic intestinal inflammation

CSNK2 suppresses autophagy by activating FLN-NHL-containing TRIM proteins

Macroautophagy/autophagy is a tightly regulated cellular process integral to homeostasis and innate immunity. As such, dysregulation of autophagy is associated with cancer, neurodegenerative disorders, and infectious diseases. While numerous factors that promote autophagy have been characterized, the key mechanisms that prevent excessive autophagy are less well understood. Here, we identify CSNK2/CK2 (casein kinase 2) as a negative regulator of autophagy. Pharmacological inhibition of CSNK2 activity or siRNA-mediated depletion of CSNK2 increased basal autophagic flux in cell lines and primary human lung cells. Vice versa, ectopic expression of CSNK2 reduced autophagic flux. Mechanistically, CSNK2 interacted with the FLN (filamin)-NHL domain-containing tripartite motif (TRIM) family members TRIM2, TRIM3 and TRIM71. Our data show that recruitment of CSNK2 to the C-terminal NHL domain of TRIM3 lead to its robust phosphorylation at serine 661 by CSNK2. A phosphorylation-defective mutant of TRIM3 was unable to reduce autophagosome numbers indicating that phosphorylation by CSNK2 is required for TRIM-mediated autophagy inhibition. All three TRIMs facilitated inactivation of the ULK1-BECN1 autophagy initiation complex by facilitating ULK1 serine 757 phosphorylation. Inhibition of CSNK2 promoted autophagy upon influenza A virus (IAV) and measles virus (MeV) infection. In line with this, targeting of CSNK2 or depletion of TRIM2, TRIM3 or TRIM71 enhanced autophagy-dependent restriction of IAV, MeV and human immunodeficiency virus 1 (HIV-1). Thus, our results identify the CSNK2-TRIM2, -TRIM3, -TRIM71 axis as a key regulatory pathway that limits autophagy. Targeting this axis may allow for therapeutic induction of autophagy against viral infections and in diseases associated with dysregulated autophagy.Abbreviation: ATG5: autophagy related 5; BafA1: bafilomycin A1; BECN1: beclin 1; CCD: coiled-coil domain; CSNK2/CK2: casein kinase 2; CSNK2A1: casein kinase 2 alpha 1; CSNK2A2: casein kinase 2 alpha 2; CSNK2B: casein kinase 2 beta; FLN: filamin; HeLa GL: HeLa cells stably expressing eGFP-LC3B; HIV-1: human immunodeficiency virus 1; IAV: influenza A virus; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3; MeV: measles virus; MTOR: mechanistic target of rapamycin kinase; RING: really interesting new gene; SQSTM1/p62: sequestosome 1; TRIM: tripartite motif; ULK1: unc-51 like autophagy activating kinase 1.

Phosphoproteomics changes due to allograft-induced stress responses of Pinctada fucata martensii

Protein phosphorylation modifications are post-translational modifications (PTMs) that play important roles in signal transduction and immune regulation. Implanting a spherical nucleus into a recipient shellfish is critical in marine pearl aquaculture. Protein phosphorylation may be important in the immune responses of Pinctada fucata martensii after nucleus implantation, but their involvement in regulation remains unclear. Here, phosphoproteomics of P. f. martensii gill tissues was conducted 12 h after nuclear implantation using label-free data-independent acquisition (DIA) with LC-MS/MS. Among the 4024 phosphorylated peptides with quantitative information, 181 were up-regulated and 148 were down-regulated. Functional enrichment analysis of these differentially expressed phosphorylated proteins (DEPPs) revealed significant enrichment in functions related to membrane trafficking, exosomes, cytoskeleton, and signal transduction mechanisms. Further, 16 conserved motifs were identified among the DEPPs, including the RSphP, SphP, RSphA, RSphE, PTphP, and ATphP motifs that were significantly conserved, and which may be related to specific kinase recognition. Parallel response monitoring (PRM) analysis validated the abundances of 12 DEPPs from the proteomics, indicating that the phosphoproteomics analyses were robust. 12 DEPPs were selected from the proteomics results through Quantitative real-time PCR (qPCR) technology, and verification analysis was conducted at the gene level. The study suggests that kinases such as MAPKs, Akt, and CK2 may regulate the phosphorylation of related proteins following nuclear implantation. Furthermore, the important signaling pathways of Rap 1, IL-17A, and NF-κB, which are influenced by phosphorylated or dephosphorylated proteins, are found to be involved in this response. Overall, this study revealed the protein phosphorylation responses after nucleus implantation in P. f. martensii, helping to elucidate the characteristics and mechanisms of immune regulation responses in P. f. martensii, in addition to promoting a further understanding of protein phosphorylation modification functions in P. f. martensii.

Protein Kinase CK2 Promotes Proliferation, Abnormal Differentiation, and Proinflammatory Cytokine Production of Keratinocytes via Regulation of STAT3 and Akt Pathways in Psoriasis

Protein kinase CK2 is a constitutively active and ubiquitously expressed serine/threonine kinase that is closely associated with various types of cancers, autoimmune disorders, and inflammation. However, the role of CK2 in psoriasis remains unknown. Herein, the study indicated elevated expression of CK2 in skin lesions from patients with psoriasis and from psoriasis-like mice. In the psoriasis-like mouse model, the CK2-specific inhibitor CX-4945 ameliorated imiquimod-induced psoriasis symptoms with reduced proliferation, abnormal differentiation, inflammatory cytokine production (especially IL-17A) of keratinocytes, and infiltration of γδ T cells. In in vitro studies, exogenous CK2 promoted hyperproliferation and abnormal differentiation of human keratinocytes, which were reversed by the suppression of CK2 with CX-4945 or siRNA. Furthermore, knockdown of CK2 reduced IL-17A expression and abolished IL-17A-induced proliferation and inflammatory cytokine expression in keratinocytes. Interestingly, IL-17A increased the expression of CK2 in keratinocytes, thereby establishing a positive feedback loop. In addition, suppression of CK2 inhibited the activation of STAT3 and Akt signaling pathways in human keratinocytes and imiquimod-induced psoriatic lesions of mice. These findings indicate that a highly expressed CK2 level in the skin lesions is required in the development of psoriasis by promoting epidermal hyperplasia, abnormal differentiation, and inflammatory response via regulation of the STAT3 and Akt signaling pathways. CK2 may be a target for the treatment of psoriasis.

Paracellular permeability and tight junction regulation in gut health and disease

Epithelial tight junctions define the paracellular permeability of the intestinal barrier. Molecules can cross the tight junctions via two distinct size-selective and charge-selective paracellular pathways: the pore pathway and the leak pathway. These can be distinguished by their selectivities and differential regulation by immune cells. However, permeability increases measured in most studies are secondary to epithelial damage, which allows non-selective flux via the unrestricted pathway. Restoration of increased unrestricted pathway permeability requires mucosal healing. By contrast, tight junction barrier loss can be reversed by targeted interventions. Specific approaches are needed to restore pore pathway or leak pathway permeability increases. Recent studies have used preclinical disease models to demonstrate the potential of pore pathway or leak pathway barrier restoration in disease. In this Review, we focus on the two paracellular flux pathways that are dependent on the tight junction. We discuss the latest evidence that highlights tight junction components, structures and regulatory mechanisms, their impact on gut health and disease, and opportunities for therapeutic intervention.

Casein kinase CK2 structure and activities in plants

Casein kinase CK2 is a highly conserved serine/threonine protein kinase and exists in all eukaryotes. It has been demonstrated to be widely involved in the biological processes of plants. The CK2 holoenzyme is a heterotetramer consisting of two catalytic subunits (α and/or α') and two regulatory subunits (β). CK2 in plants is generally encoded by multiple genes, with monomeric and oligomeric forms present in the tissue. Various subunit genes of CK2 have been cloned and characterized from Arabidopsis thaliana, tobacco, maize, wheat, tomato, and other plants. This paper reviews the structural features of CK2, provides a clear classification of its physiological functions and mechanisms of action, and elaborates on the regulation of CK2 activity to provide a knowledge base for subsequent studies of CK2 in plants.

Casein kinase 2 attenuates brain injury induced by intracerebral hemorrhage via regulation of NR2B phosphorylation

Objective

Intracerebral hemorrhage (ICH) is a common cerebrovascular disease with high incidence, disability, and mortality. Casein kinase 2 (CK2) is a serine/threonine kinase with hundreds of identified substrates and plays an important role in many diseases. This study aimed to explore whether CK2 plays protective roles in ICH-induced neuronal apoptosis, inflammation, and oxidative stress through regulation NR2B phosphorylation.

Methods

CK2 expression level of brain tissues taken from ICH patients was determined by immunoblotting. Neurons from embryonic rat and astrocytes from newborn rats were cultured and treated by Hemoglobin chloride (Hemin). The proliferation of astrocytes, the apoptosis and oxidative stress of neurons and the inflammatory factors of astrocytes were detected. CK2 expression was determined in ICH model rats. The effects of CK2 overexpression plasmid (pc-CK2) on neurobehavioral defects and brain water content in ICH rats were observed.

Results

CK2 expression in ICH patients was down-regulated. Overexpression of CK2 promoted the astrocyte proliferation, inhibited neuronal apoptosis, and reduced astrocyte-mediated inflammation. N-methyl-D-aspartate receptor 2B (NR2B) reversed the effects of pc-CK2 on neurons and astrocytes. CK2 phosphorylated NR2B at the S1480 site, down-regulated the expression of NR2B and interfered with the interaction between NR2B and postsynaptic density protein 95 (PSD95). In vivo experiments showed that the expression of CK2 decreased and the expression of NR2B increased in ICH rats. Furthermore, pc-CK2 attenuated neurobehavioral defects, brain water content and neuronal damage in ICH rats.

Conclusion

CK2 phosphorylated NR2B, down-regulated the expression of NR2B, interfered with the interaction between NR2B and PSD95, alleviated inflammatory reactions, inhibited neuronal apoptosis and oxidative stress after ICH. CK2 and NR2B may be new potential therapeutic targets for the treatment of ICH. However, the limitation of this study is that we only investigated the regulation of NR2B by CK2.

Telocytes’ Role in Modulating Gut Motility Function and Development: Medical Hypotheses and Literature Review

This review article explores the telocytes’ roles in inflammatory bowel diseases (IBD), presenting the mechanisms and hypotheses related to epithelial regeneration, progressive fibrosis, and dysmotility as a consequence of TCs’ reduced or absent number. Based on the presented mechanisms and hypotheses, we aim to provide a functional model to illustrate TCs’ possible roles in the normal and pathological functioning of the digestive tract. TCs are influenced by the compression of nearby blood vessels and the degree of fibrosis of the surrounding tissues and mediate these processes in response. The changes in intestinal tube vascularization induced by the movement of the food bowl, and the consequent pH changes that show an anisotropy in the thickness of the intestinal tube wall, have led to the identification of a pattern of intestinal tube development based on telocytes’ ability to communicate and modulate surrounding cell functions. In the construction of the theoretical model, given the predictable occurrence of colic in the infant, the two-layer arrangement of the nerve plexuses associated with the intestinal tube was considered to be incompletely adapted to the motility required with a diversified diet. There is resulting evidence of possible therapeutic targets for diseases associated with changes in local nerve tissue development.

Evaluation of a Selective Chemical Probe Validates That CK2 Mediates Neuroinflammation in a Human Induced Pluripotent Stem Cell-Derived Microglial Model

Novel treatments for neurodegenerative disorders are in high demand. It is imperative that new protein targets be identified to address this need. Characterization and validation of nascent targets can be accomplished very effectively using highly specific and potent chemical probes. Human induced pluripotent stem cells (hiPSCs) provide a relevant platform for testing new compounds in disease relevant cell types. However, many recent studies utilizing this platform have focused on neuronal cells. In this study, we used hiPSC-derived microglia-like cells (MGLs) to perform side-by-side testing of a selective chemical probe, SGC-CK2-1, compared with an advanced clinical candidate, CX-4945, both targeting casein kinase 2 (CK2), one of the first kinases shown to be dysregulated in Alzheimer's disease (AD). CK2 can mediate neuroinflammation in AD, however, its role in microglia, the innate immune cells of the central nervous system (CNS), has not been defined. We analyzed available RNA-seq data to determine the microglial expression of kinases inhibited by SGC-CK2-1 and CX-4945 with a reported role in mediating inflammation in glial cells. As proof-of-concept for using hiPSC-MGLs as a potential screening platform, we used both wild-type (WT) MGLs and MGLs harboring a mutation in presenilin-1 (PSEN1), which is causative for early-onset, familial AD (FAD). We stimulated these MGLs with pro-inflammatory lipopolysaccharides (LPS) derived from E. coli and observed strong inhibition of the expression and secretion of proinflammatory cytokines by simultaneous treatment with SGC-CK2-1. A direct comparison shows that SGC-CK2-1 was more effective at suppression of proinflammatory cytokines than CX-4945. Together, these results validate a selective chemical probe, SGC-CK2-1, in human microglia as a tool to reduce neuroinflammation.

Protein Kinase CK2 Acts as a Molecular Brake to Control NADPH Oxidase 1 Activation and Colon Inflammation

BACKGROUND & AIMS

NADPH oxidase 1 (NOX1) has emerged as a prime regulator of intestinal mucosa immunity and homeostasis. Dysregulation of NOX1 may cause inflammatory bowel disease (IBD). It is not clear how NOX1 is regulated in vivo under inflammatory conditions. We studied the role of CK2 in this process.

METHODS

The NOX1 organizer subunit, NADPH oxidase organizer 1 (NOXO1), was immunoprecipitated from cytokine-treated colon epithelial cells, and bound proteins were identified by mass spectrometry analysis. Sites on NOXO1 phosphorylated by CK2 were identified by nanoscale liquid chromatography coupled to tandem mass spectrometry. NOX1 activity was determined in colon epithelial cells and colonoids in the presence or absence of CX-4945, a CK2 specific inhibitor. Acute colitis was induced by administration of trinitrobenzenesulfonic acid in mice treated or not with CX-4945. Colon tissues were analyzed by histologic examination, quantitative polymerase chain reaction, and Western blots. CK2 activity, markers of inflammation, and oxidative stress were assessed.

RESULTS

We identified CK2 as a major partner of NOXO1 in colon epithelial cells under inflammatory conditions. CK2 directly binds NOXO1 at the C-terminus containing the Phox homology domain and phosphorylates NOXO1 on several sites. CX-4945 increased ROS generation by NOX1 in human colon epithelial cells and organoids. Strikingly, CK2 activity was reduced in trinitrobenzenesulfonic acid-induced acute colitis, and CX-4945 exacerbated colitis inflammation as shown by increased levels of CXCL1, ROS generation, lipid peroxidation, and colon damage.

CONCLUSIONS

The ubiquitous protein kinase CK2 limits NOX1 activity via NOXO1 binding and phosphorylation in colonic epithelial cells and lessens experimental colitis. Loss of CK2 activity during acute colitis results in excessive ROS production, contributing to the pathogenesis. Strategies to activate CK2 could be an effective novel therapeutic approach in IBD.

Rutin prevents inflammation-associated colon damage via inhibiting the p38/MAPKAPK2 and PI3K/Akt/GSK3β/NF-κB signalling axes and enhancing splenic Tregs in DSS-induced murine chronic colitis

A large body of emerging evidence has revealed the role of p38/MK2 and PI3K/Akt/GSK3β cascades in the orchestrating process of colitis. Rutin, a bioflavonoid present in many fruits and vegetables, has been recognized to offer therapeutic attributes in acute colitis. However, its role in chronic colitic condition has not yet been delineated in reference to p38/MK2 and PI3K/Akt/GSK3β signalling. The present investigation assessed the efficacy and underlying molecular mechanism of rutin in alleviating DSS-induced chronic colitis. The analysis of signalling pathways demonstrated the robust activation of PI3K/Akt/GSK3β/MAPKs/NF-κB and p38/MK2 in DSS-induced colitis in animals, which was efficiently alleviated following the rutin treatment. In silico studies indicated its target specificity with these pathways. Rutin administration markedly improved the disease activity score, colon length, goblet cell loss and compromised colon epithelial integrity in colitic mice. Decreased expression of oxi-inflammatory markers such as IgM, IgE, iNOS, ICAM-1, HO-1 and Th1/IL-10 cytokines ratios after treatment suggests its efficacy in regulating effector, regulatory and B cell homeostasis. Additionally, rutin demonstrated its role in restoring epithelial integrity by modulating the transcript levels of tight junction proteins, mucus-secreting proteins, epithelial cell proliferation and apoptosis. Treg expansion revealed that rutin supplementation also exhibits an immune regulatory potential and suppresses inflammatory aggravation mediated by adaptive immune responses. Overall, results indicate that the modulation of p38/MK2 and PI3K/Akt/GSK3β/NF-κB pathways by rutin represents a novel therapeutic approach in chronic colitis that help to curb dysregulated intestinal integrity, cytokine ratio and splenic Tregs.

Intestinal permeability in type 1 diabetes: An updated comprehensive overview

The etiopathogenesis of the autoimmune disease type 1 diabetes (T1D) is still largely unknown, however, both genetic and environmental factors contribute to the development of the disease. A major contact surface for environmental factors is the gastrointestinal (GI) tract, where barrier defects in T1D likely cause diabetogenic antigens to enter the body tissues, contributing to beta-cell autoimmunity. Human and animal research imply that increased intestinal permeability is an important disease determinant, although the underlying methodologies, interpretations and conclusions are diverse. In this review, an updated comprehensive overview on intestinal permeability in patients with T1D and animal models of T1D is provided in the categories: in vivo permeability, ex vivo permeability, zonulin, molecular permeability and blood markers. Across categories, there is consistency pointing towards increased intestinal permeability in T1D. In animal models of T1D, the intestinal permeability varies with age and strains implying a need for careful selection of method and experimental setup. Furthermore, dietary interventions that affect diabetes incidence in animal models does also impact the intestinal permeability, suggesting an association between increased intestinal permeability and T1D development.

Chemical probes targeting the kinase CK2: a journey outside the catalytic box

CK2 is a protein kinase that plays important roles in many physio-pathological cellular processes. As such, the development of chemical probes for CK2 has received increasing attention in the past decade with more than 40 lead compounds developed. In this review, we aim to provide the reader with a comprehensive overview of the chemical probes acting outside the highly-conserved ATP-site developed to date. Such probes belong to different classes of molecules spanning from small molecules to peptides, act with a range of mechanisms of action and some of them present themselves as promising tools to investigate the biology of CK2 and therefore develop therapeutics for many disease areas including cancer and COVID-19.

Protein kinase CK2: a potential therapeutic target for diverse human diseases

CK2 is a constitutively active Ser/Thr protein kinase, which phosphorylates hundreds of substrates, controls several signaling pathways, and is implicated in a plethora of human diseases. Its best documented role is in cancer, where it regulates practically all malignant hallmarks. Other well-known functions of CK2 are in human infections; in particular, several viruses exploit host cell CK2 for their life cycle. Very recently, also SARS-CoV-2, the virus responsible for the COVID-19 pandemic, has been found to enhance CK2 activity and to induce the phosphorylation of several CK2 substrates (either viral and host proteins). CK2 is also considered an emerging target for neurological diseases, inflammation and autoimmune disorders, diverse ophthalmic pathologies, diabetes, and obesity. In addition, CK2 activity has been associated with cardiovascular diseases, as cardiac ischemia-reperfusion injury, atherosclerosis, and cardiac hypertrophy. The hypothesis of considering CK2 inhibition for cystic fibrosis therapies has been also entertained for many years. Moreover, psychiatric disorders and syndromes due to CK2 mutations have been recently identified. On these bases, CK2 is emerging as an increasingly attractive target in various fields of human medicine, with the advantage that several very specific and effective inhibitors are already available. Here, we review the literature on CK2 implication in different human pathologies and evaluate its potential as a pharmacological target in the light of the most recent findings.

How can a traffic light properly work if it is always green? The paradox of CK2 signaling

CK2 is a constitutively active protein kinase that assuring a constant level of phosphorylation to its numerous substrates supports many of the most important biological functions. Nevertheless, its activity has to be controlled and adjusted in order to cope with the varying needs of a cell, and several examples of a fine-tune regulation of its activity have been described. More importantly, aberrant regulation of this enzyme may have pathological consequences, e.g. in cancer, chronic inflammation, neurodegeneration, and viral infection. Our review aims at summarizing our current knowledge about CK2 regulation. In the first part, we have considered the most important stimuli shown to affect protein kinase CK2 activity/expression. In the second part, we focus on the molecular mechanisms by which CK2 can be regulated, discussing controversial aspects and future perspectives.

Myeloid Cell CK2 Regulates Inflammation and Resistance to Bacterial Infection

Kinase activity plays an essential role in the regulation of immune cell defenses against pathogens. The protein kinase CK2 (formerly casein kinase II) is an evolutionarily conserved kinase with hundreds of identified substrates. CK2 is ubiquitously expressed in somatic and immune cells, but the roles of CK2 in regulation of immune cell function remain largely elusive. This reflects the essential role of CK2 in organismal development and limited prior work with conditional CK2 mutant murine models. Here, we generated mice with a conditional (floxed) allele of Csnk2a, which encodes the catalytic CK2α subunit of CK2. When crossed to Lyz2-cre mice, excision of Csnk2a sequence impaired CK2α expression in myeloid cells but failed to detectably alter myeloid cell development. By contrast, deficiency for CK2α increased inflammatory myeloid cell recruitment, activation, and resistance following systemic Listeria monocytogenes (Lm) infection. Results from mixed chimera experiments indicated that CK2α deficiency in only a subset of myeloid cells was not sufficient to reduce bacterial burdens. Nor did cell-intrinsic deficiency for CK2α suffice to alter accumulation or activation of monocytes and neutrophils in infected tissues. These data suggest that CK2α expression by Lyz2-expressing cells promotes inflammatory and anti-bacterial responses through effects in trans. Our results highlight previously undescribed suppressive effects of CK2 activity on inflammatory myeloid cell responses and illustrate that cell-extrinsic effects of CK2 can shape inflammatory and protective innate immune responses.

Inactivation of paracellular cation-selective claudin-2 channels attenuates immune-mediated experimental colitis in mice

The tight junction protein claudin-2 is upregulated in disease. Although many studies have linked intestinal barrier loss to local and systemic disease, these have relied on macromolecular probes. In vitro analyses show, however, that these probes cannot be accommodated by size- and charge-selective claudin-2 channels. We sought to define the impact of claudin-2 channels on disease. Transgenic claudin-2 overexpression or IL-13-induced claudin-2 upregulation increased intestinal small cation permeability in vivo. IL-13 did not, however, affect permeability in claudin-2-knockout mice. Claudin-2 is therefore necessary and sufficient to effect size- and charge-selective permeability increases in vivo. In chronic disease, T cell transfer colitis severity was augmented or diminished in claudin-2-transgenic or -knockout mice, respectively. We translated the in vitro observation that casein kinase-2 (CK2) inhibition blocks claudin-2 channel function to prevent acute, IL-13-induced, claudin-2-mediated permeability increases in vivo. In chronic immune-mediated colitis, CK2 inhibition attenuated progression in claudin-2-sufficient, but not claudin-2-knockout, mice, i.e., the effect was claudin-2 dependent. Paracellular flux mediated by claudin-2 channels can therefore promote immune-mediated colitis progression. Although the mechanisms by which claudin-2 channels intensify disease remain to be defined, these data suggest that claudin-2 may be an accessible target in immune-mediated disorders, including inflammatory bowel disease.

Stress granules in colorectal cancer: Current knowledge and potential therapeutic applications

Stress granules (SGs) represent important non-membrane cytoplasmic compartments, involved in cellular adaptation to various stressful conditions (e.g., hypoxia, nutrient deprivation, oxidative stress). These granules contain several scaffold proteins and RNA-binding proteins, which bind to mRNAs and keep them translationally silent while protecting them from harmful conditions. Although the role of SGs in cancer development is still poorly known and vary between cancer types, increasing evidence indicate that the expression and/or the activity of several key SGs components are deregulated in colorectal tumors but also in pre-neoplastic conditions (e.g., inflammatory bowel disease), thus suggesting a potential role in the onset of colorectal cancer (CRC). It is therefore believed that SGs formation importantly contributes to various steps of colorectal tumorigenesis but also in chemoresistance. As CRC is the third most frequent cancer and one of the leading causes of cancer mortality worldwide, development of new therapeutic targets is needed to offset the development of chemoresistance and formation of metastasis. Abolishing SGs assembly may therefore represent an appealing therapeutic strategy to re-sensitize colon cancer cells to anti-cancer chemotherapies. In this review, we summarize the current knowledge on SGs in colorectal cancer and the potential therapeutic strategies that could be employed to target them.

Protein kinase 2 (CK2) controls CD4+ T cell effector function in the pathogenesis of colitis

Crohn's disease (CD), one of the major forms of inflammatory bowel disease (IBD), is characterized by chronic inflammation of the gastrointestinal tract and associated with aberrant CD4⁺ T-helper type 1 (Th1) and Th17 responses. Protein kinase 2 (CK2) is a conserved serine-threonine kinase involved in signal transduction pathways, which regulate immune responses. CK2 promotes Th17 cell differentiation and suppresses the generation of Foxp3⁺ regulatory T cells. The function of CK2 in CD4⁺ T cells during the pathogenesis of CD is unknown. We utilized the T cell-induced colitis model, transferring CD45RB^hi-naive CD4⁺ T cells from CK2α^fl/fl controls and CK2α^fl/fldLck-Cre mice into Rag1^-/- mice. CD4⁺ T cells from CK2α^fl/fldLck-Cre mice failed to induce wasting disease and significant intestinal inflammation, which was associated with decreased interleukin-17A-positive (IL-17A⁺), interferon-γ-positive (IFN-γ⁺), and double-positive IL-17A⁺IFN-γ⁺ CD4⁺ T cells in the spleen and colon. We determined that CK2α regulates CD4⁺ T cell proliferation through a cell-intrinsic manner. CK2α is also important in controlling CD4⁺ T cell responses by regulating NFAT2, which is vital for T cell activation and proliferation. Our findings indicate that CK2α contributes to the pathogenesis of colitis by promoting CD4⁺ T cell proliferation and Th1 and Th17 responses, and that targeting CK2 may be a novel therapeutic treatment for patients with CD.

Protein Kinase CK2 in Cancer Energetics

Protein kinase CK2 (formerly known as casein kinase 2) is abnormally elevated in many cancers. This may increase tumor aggressiveness through CK2-dependent phosphorylation of key proteins in several signaling pathways. In this work, we have compiled evidence from the literature to suggest that CK2 also modulates a metabolic switch characteristic of cancer cells that enhances resistance to death, due to either drugs or to a microenvironment deficient in oxygen or nutrients. Concurrently, CK2 may help to preserve mitochondrial activity in a PTEN-dependent manner. PTEN, widely recognized as a tumor suppressor, is another CK2 substrate in the PI3K/Akt signaling pathway that promotes cancer viability and aerobic glycolysis. Given that CK2 can regulate Akt as well as two of its main effectors, namely mTORC1 and β-catenin, we comprehensively describe how CK2 may modulate cancer energetics by regulating expression of key targets and downstream processes, such as HIF-1 and autophagy, respectively. Thus, the specific inhibition of CK2 may lead to a catastrophic death of cancer cells, which could become a feasible therapeutic strategy to beat this devastating disease. In fact, ATP-competitive inhibitors, synthetic peptides and antisense oligonucleotides have been designed as CK2 inhibitors, some of them used in preclinical models of cancer, of which TBB and silmitasertib are widely known. We will finish by discussing a hypothetical scenario in which cancer cells are "addicted" to CK2; i.e., in which many proteins that regulate signaling pathways and metabolism-linked processes are highly dependent on this kinase.

Tight Junctions as Targets and Effectors of Mucosal Immune Homeostasis

Defective epithelial barrier function is present in maladies including epidermal burn injury, environmental lung damage, renal tubular disease, and a range of immune-mediated and infectious intestinal disorders. When the epithelial surface is intact, the paracellular pathway between cells is sealed by the tight junction. However, permeability of tight junctions varies widely across tissues and can be markedly impacted by disease. For example, tight junctions within the skin and urinary bladder are largely impermeant and their permeability is not regulated. In contrast, tight junctions of the proximal renal tubule and intestine are selectively permeable to water and solutes on the basis of their biophysical characteristics and, in the gut, can be regulated by the immune system with remarkable specificity. Conversely, modulation of tight junction barrier conductance, especially within the gastrointestinal tract, can impact immune homeostasis and diverse pathologies. Thus, tight junctions are both effectors and targets of immune regulation. Using the gastrointestinal tract as an example, this review explores current understanding of this complex interplay between tight junctions and immunity.

Litopenaeus vannamei CK2 is involved in shrimp innate immunity by modulating hemocytes apoptosis

Protein kinase CK2 (CK2) is a ubiquitous serine/threonine kinase with multiple cellular functions in vertebrates including apoptosis, differentiation, proliferation, survival, tumorigenesis, signal transduction, immune regulation and inflammation. In the current study, the catalytic and regulatory subunit homologs of Litopenaeus vannamei protein kinase CK2 (LvCK2α and LvCK2β) were cloned and characterized. LvCK2α has a full-length cDNA sequence of 1764 bp with a 1053 bp open reading frame (ORF) encoding a putative protein of 351 amino acids, which contains a typical serine/threonine kinase domain. On the other hand, LvCK2β has a 1394 bp full-length cDNA with an ORF of 663 bp encoding a protein with 221 amino acids, which contains a Casein kinase II regulatory subunit domain. Sequence and phylogenetic analysis revealed that LvCK2 was evolutionary related with the CK2 of invertebrates. Quantitative reverse transcription PCR (RT-qPCR) analysis showed that LvCK2α and LvCK2β transcripts were widely expressed in all shrimp tissues tested, and were both induced in hemocytes and hepatopancreas upon challenge with Vibrio parahaemolyticus, Streptoccocus iniae, lipopolysaccharide (LPS), and white spot syndrome virus (WSSV), suggesting their involvement in shrimp immune response. Moreover, RNA interference (RNAi) of LvCK2α resulted in increased hemocytes apoptosis, shown by high caspase 3/7 activity, increased number of apoptotic cells, coupled with an elevation in transcript levels of pro-apoptotic LvCaspase3 and LvCytochrome C, and a reduction in mRNA levels of pro-survival LvBcl2, LvIAP1, and LvIAP2. In addition, LvCK2α knockdown followed by V. parahaemolyticus challenge resulted in higher cumulative mortality of shrimp. Taken together, our current findings suggest that LvCK2 modulates shrimp hemocytes apoptosis as part of the innate immune response to pathogens.

Design of CK2β-Mimicking Peptides as Tools To Study the CK2α/CK2β Interaction in Cancer Cells

The ubiquitously expressed Ser/Thr kinase CK2 is a key regulator in a variety of key processes in normal and malignant cells. Due to its distinctive anti-apoptotic and tumor-driving properties, elevated levels of CK2 have frequently been found in tumors of different origin. In recent years, development of CK2 inhibitors has largely been focused on ATP-competitive compounds; however, targeting the CK2α/CK2β interface has emerged as a further concept that might avoid selectivity issues. To address the CK2 subunit interaction site, we have synthesized halogenated CK2β-mimicking cyclic peptides modified with the cell-penetrating peptide sC18 to mediate cellular uptake. We investigated the binding of the resulting chimeric peptides to recombinant human CK2α using a recently developed fluorescence anisotropy assay. The iodinated peptide sC18-I-Pc was identified as a potent CK2α ligand (K_i =0.622 μm). It was internalized in cells to a high extent and exhibited significant cytotoxicity toward cancerous HeLa cells (IC₅₀ =37 μm) in contrast to non-cancerous HEK-293 cells. The attractive features and functionalities of sC18-I-Pc offer the opportunity for further improvement.

Threonine 454 phosphorylation in Grainyhead-like 3 is important for its function and regulation by the p38 MAPK pathway

The mammalian Grainyhead-like 3 (GRHL3) transcription factor is essential for epithelial development and plays a protective role against squamous cell carcinoma of the skin and of the oral cavity. A single nucleotide polymorphism (SNP) in GRHL3, rs141193530 (p.P455A), is associated with non-melanoma skin cancer in human patients. Moreover, it is known that this SNP, as well as another variant, rs41268753 (p.T454M), are associated with nonsyndromic cleft palate and that rs41268753 negatively affects GRHL3 transcriptional activity. These SNPs are located in adjacent codons of the GRHL3 gene, and the occurrence of either SNP abolishes a putative threonine-proline phosphorylation motif at T454 in the encoded protein. The role of phosphorylation in regulating mammalian GRHL function is currently unknown. In this work we show that GRHL3 is phosphorylated at several residues in a human keratinocyte cell line, among them at T454. This site is essential for the full transcriptional activity of GRHL3. The T454 residue is phosphorylated by p38 MAPK in vitro and activation of p38 signaling in cells causes an increase in GRHL3 activity. The regulation of GRHL3 function by this pathway is dependent on T454, as the substitution of T454 with methionine inhibits the activation of GRHL3. Taken together, our results show that T454 is one of the phosphorylated residues in GRHL3 in keratinocytes and this residue is important for the upregulation of GRHL3 transcriptional activity by the p38 pathway.

The importance of negative determinants as modulators of CK2 targeting. The lesson of Akt2 S131

CK2 is a pleiotropic S/T protein kinase (formerly known as casein kinase 2) which is attracting increasing interest as therapeutic target, and the identification of its substrates is a crucial step in determining its involvement in different pathological conditions. We recently found that S131 of Akt2 (homologous to the well established CK2 target S129 of Akt1) is not phosphorylated by CK2 either in vitro or in vivo, although the consensus sequence recognized by CK2 (S/T-x-x-E/D/pS/pT) is conserved in it. Here, by exploiting synthetic peptides, in cell transfection experiments, and computational analysis, we show that a single sequence element, a T at position n+1, hampers phosphorylation, causing an α-helix structure organization which prevents the recognition of its own consensus by CK2. Our results highlight the role of negative determinants as crucial modulators of CK2 targeting and corroborate the concept that Akt1 and Akt2 display isoform specific features. Experiments with synthetic peptides suggest that Akt2 S131 could be phosphorylated by kinases of the Plk (Polo-like kinase) family, which are insensitive to the presence of the n+1 T. The low phylogenetic conservation of the Akt2 sequence around S131, as opposed to the extremely well-conserved Akt1 homologous sequence, would indicate a dominant positive role in the selective pressure only for the Akt1 phosphoacceptor site committed to undergo phosphorylation by CK2. By contrast, Akt2 S131 may mediate the response to specific physio/pathological conditions, being consequently shielded against basal CK2 targeting.

Protein Kinase CK2: An Emerging Regulator of Immunity

Although it has historically been studied in the context of cancer, recent literature has highlighted the importance of the highly conserved serine/threonine kinase casein kinase II (CK2) in inflammatory disorders. Most strikingly, CK2 is a major regulator of the Th17-Treg axis relevant to many T cell-driven autoimmune disorders including multiple sclerosis (MS).

Modulation of transcriptional mineralocorticoid receptor activity by casein kinase 2

The pathogenesis of cardiovascular diseases is a multifunctional process in which the mineralocorticoid receptor (MR), a ligand-dependent transcription factor, is involved as proven by numerous clinical studies. The development of pathophysiological MR actions depends on the existence of additional factors e.g. inflammatory cytokines and seems to involve posttranslational MR modifications e.g. phosphorylation. Casein kinase 2 (CK2) is a ubiquitously expressed multifunctional serine/threonine kinase that can be activated under inflammatory conditions as the MR. Sequence analysis and inhibitor experiments revealed that CK2 acts as a positive modulator of MR activity by facilitating MR-DNA interaction with subsequent rapid MR degradation. Peptide microarrays and site-directed mutagenesis experiments identified the highly conserved S459 as a functionally relevant CK2 phosphorylation site of the MR. Moreover, MR-CK2 protein-protein interaction mediated by HSP90 was shown by co-immunoprecipitation. During inflammation, cytokine stimulation led to a CK2-dependent increased expression of proinflammatory genes. The additional MR activation by aldosterone during cytokine stimulation augmented CK2-dependent NFκB signaling which enhanced the expression of proinflammatory genes further. Overall, in an inflammatory environment the bidirectional CK2-MR interaction aggravate the existing pathophysiological cellular situation.

Casein kinase 2 controls the survival of normal thymic and leukemic γδ T cells via promotion of AKT signaling

The thymus is the major site for normal and leukemic T-cell development. The dissection of the molecular determinants of T-cell survival and differentiation is paramount for the manipulation of healthy or transformed T cells in cancer (immuno)therapy. Casein kinase 2 (CK2) is a serine/threonine protein kinase whose anti-apoptotic functions have been described in various hematological and solid tumors. Here we disclose an unanticipated role of CK2 in healthy human thymocytes that is selective to the γδ T-cell lineage. γδ thymocytes display higher (and T-cell receptor inducible) CK2 activity than their αβ counterparts, and are strikingly sensitive to death upon CK2 inhibition. Mechanistically, we show that CK2 regulates the pro-survival AKT signaling pathway in γδ thymocytes and, importantly, also in γδ T-cell acute lymphoblastic leukemia (T-ALL) cells. When compared with healthy thymocytes or leukemic αβ T cells, γδ T-ALL cells show upregulated CK2 activity, potentiated by CD27 costimulation, and enhanced apoptosis upon CK2 blockade using the chemical inhibitor CX-4945. Critically, this results in inhibition of tumor growth in a xenograft model of human γδ T-ALL. These data identify CK2 as a novel survival determinant of both healthy and leukemic γδ T cells, and may thus greatly impact their therapeutic manipulation.

Shifts in the Gut Microbiota Composition Due to Depleted Bone Marrow Beta Adrenergic Signaling Are Associated with Suppressed Inflammatory Transcriptional Networks in the Mouse Colon

The brain-gut axis plays a critical role in the regulation of different diseases, many of which are characterized by sympathetic dysregulation. However, a direct link between sympathetic dysregulation and gut dysbiosis remains to be illustrated. Bone marrow (BM)-derived immune cells continuously interact with the gut microbiota to maintain homeostasis in the host. Their function is largely dependent upon the sympathetic nervous system acting via adrenergic receptors present on the BM immune cells. In this study, we utilized a novel chimera mouse that lacks the expression of BM beta1/2 adrenergic receptors (b1/2-ARs) to investigate the role of the sympathetic drive to the BM in gut and microbiota homeostasis. Fecal analyses demonstrated a shift from a dominance of Firmicutes to Bacteroidetes phylum in the b1/2-ARs KO chimera, resulting in a reduction in Firmicutes/Bacteroidetes ratio. Meanwhile, a significant reduction in Proteobacteria phylum was determined. No changes in the abundance of acetate-, butyrate-, and lactate-producing bacteria, and colon pathology were observed in the b1/2-ARs KO chimera. Transcriptomic profiling in colon identified Killer Cell Lectin-Like Receptor Subfamily D, Member 1 (Klrd1), Membrane-Spanning 4-Domains Subfamily A Member 4A (Ms4a4b), and Casein Kinase 2 Alpha Prime Polypeptide (Csnk2a2) as main transcripts associated with the microbiota shifts in the b1/2-ARs KO chimera. Suppression of leukocyte-related transcriptome networks (i.e., function, differentiation, migration), classical compliment pathway, and networks associated with intestinal function, barrier integrity, and excretion was also observed in the colon of the KO chimera. Moreover, reduced expression of transcriptional networks related to intestinal diseases (i.e., ileitis, enteritis, inflammatory lesions, and stress) was noted. The observed suppressed transcriptome networks were associated with a reduction in NK cells, macrophages, and CD4⁺ T cells in the b1/2-ARs KO chimera colon. Thus, sympathetic regulation of BM-derived immune cells plays a significant role in modifying inflammatory networks in the colon and the gut microbiota composition. To our knowledge, this study is the first to suggest a key role of BM b1/2-ARs signaling in host-microbiota interactions, and reveals specific molecular mechanisms that may lead to generation of novel anti-inflammatory treatments for many immune and autonomic diseases as well as gut dysbiosis across the board.

Inflammation and the Intestinal Barrier: Leukocyte-Epithelial Cell Interactions, Cell Junction Remodeling, and Mucosal Repair

The intestinal tract is lined by a single layer of columnar epithelial cells that forms a dynamic, permeable barrier allowing for selective absorption of nutrients, while restricting access to pathogens and food-borne antigens. Precise regulation of epithelial barrier function is therefore required for maintaining mucosal homeostasis and depends, in part, on barrier-forming elements within the epithelium and a balance between pro- and anti-inflammatory factors in the mucosa. Pathologic states, such as inflammatory bowel disease, are associated with a leaky epithelial barrier, resulting in excessive exposure to microbial antigens, recruitment of leukocytes, release of soluble mediators, and ultimately mucosal damage. An inflammatory microenvironment affects epithelial barrier properties and mucosal homeostasis by altering the structure and function of epithelial intercellular junctions through direct and indirect mechanisms. We review our current understanding of complex interactions between the intestinal epithelium and immune cells, with a focus on pathologic mucosal inflammation and mechanisms of epithelial repair. We discuss leukocyte-epithelial interactions, as well as inflammatory mediators that affect the epithelial barrier and mucosal repair. Increased knowledge of communication networks between the epithelium and immune system will lead to tissue-specific strategies for treating pathologic intestinal inflammation.

The pro-inflammatory cytokines IFNγ/TNFα increase chromogranin A-positive neuroendocrine cells in the colonic epithelium

The gastrointestinal tract is the largest hormone-producing organ in the body due to a specialized cell population called enteroendocrine cells (EECs). The number of EECs increases in the mucosa of inflammatory bowel disease patients; however, the mechanisms responsible for these changes remain unknown. Here, we show that the pro-inflammatory cytokines interferon γ (IFNγ) and tumor necrosis factor α (TNFα) or dextran sulfate sodium (DSS)-induced colitis increase the number of EECs producing chromogranin A (CgA) in the colonic mucosa of C57BL/6J mice. CgA-positive cells were non-proliferating cells enriched with inactive phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and autophagy markers. Moreover, inhibition of Akt and autophagy prevented the increase in CgA-positive cells after IFNγ/TNFα treatment. Similarly, we observed that CgA-positive cells in the colonic mucosa of patients with colitis expressed Akt and autophagy markers. These findings suggest that Akt signaling and autophagy control differentiation of the intestinal EEC lineage during inflammation.

The Effects of a Selective CK2 Inhibitor on Anti-glomerular Basement Membrane Glomerulonephritis in Rats

Protein kinase CK2 ("casein kinase II") is a protein serine/threonine kinase that plays critical roles in biological processes such as cell growth, cell cycle progression, and apoptosis. So far, we have identified that one catalytic isozyme of CK2, CK2α, is over-expressed in the kidney during the progression of glomerulonephritis (GN). Moreover, we have shown that in vivo inhibition of CK2 by administration of CK2 inhibitors was effective in the treatment of experimental GN. Hence the development of potent CK2 inhibitors should be considered in therapeutic strategies for GN. In the present study we identified compound 13, a pyrazine derivative, as a potent CK2 inhibitor. By performing enzyme kinetics analysis in vitro, we characterized the inhibition of compound 13 toward each CK2 catalytic isozyme. Furthermore, in vivo, we demonstrated that compound 13 is effective in attenuating proteinuria, decreasing the enhanced level of blood urea nitrogen and serum creatinine, and ameliorating glomerular crescent formation in an experimental GN rat model. On the other hand, cellular apoptosis was detected in the rat testis following administration of compound 13. This study provides clues for new strategies for developing applicable compounds into CK2-targeted GN treatments.

Sam68 modulates apoptosis of intestinal epithelial cells via mediating NF-κB activation in ulcerative colitis

Sam68 (Src-associated substrate during mitosis of 68 KDa), also known as KHDRBS1 (KH domain containing, RNA binding, signal transduction associated 1), belongs to the prototypic member of the signal transduction activator of RNA (STAR) family of RNA-binding proteins. Sam68 is implicated in various cellular processes including RNA metabolism, apoptosis, signal transduction. Previous researches demonstrated that Sam68 regulated nuclear transcription factor kappa B (NF-κB) to induce inflammation. However, the expression and biological functions of Sam68 in ulcerative colitis (UC) are not clear. In this study, we reported for the first time that Sam68 was up-regulated in intestinal epithelial cells (IECs) of patients with UC. In DSS-induced mouse colitis model, we observed the overexpression of Sam68 accompanied with increased levels of IEC apoptotic markers (active caspase-3 and cleaved PARP) and NF-κB activation indicators (p-p65 and p-IκB) in colitis IECs. Co-localization of Sam68 with active caspase-3 (and p-p65) in IECs of the DSS-induced colitis group further indicated the possible involvement of NF-κB-mediated IEC apoptosis. Applying TNF-α-treated HT-29 cells as an in vitro IEC inflammation model, we confirmed the positive correlation amomg Sam68, NF-κB activation and caspase-dependent apoptosis. Immunofluorescence and immunoprecipitation assay identified nuclear translocation and physical interaction of Sam68 and NF-κB subunits in TNF-α-treated HT-29 cells. Besides, depletion of Sam68 by RNA interference greatly alleviated NF-κB activation and apoptosis in TNF-α-treated HT-29 cells. Taken together, our results indicated that Sam68 modulates apoptosis of intestinal epithelial cells via mediating NF-κB activation in UC.

Protein kinase CK2 in breast cancer: the CK2β regulatory subunit takes center stage in epithelial plasticity

Structurally, protein kinase CK2 consists of two catalytic subunits (α and α') and two regulatory subunits (β), which play a critical role in targeting specific CK2 substrates. Compelling evidence shows the complexity of the CK2 cellular signaling network and supports the view that this enzyme is a key component of regulatory protein kinase networks that are involved in several aspects of cancer. CK2 both activates and suppresses the expression of a number of essential oncogenes and tumor suppressors, and its expression and activity are upregulated in blood tumors and virtually all solid tumors. The prognostic significance of CK2α expression in association with various clinicopathological parameters highlighted this kinase as an adverse prognostic marker in breast cancer. In addition, several recent studies reported its implication in the regulation of the epithelial-to-mesenchymal transition (EMT), an early step in cancer invasion and metastasis. In this review, we briefly overview the contribution of CK2 to several aspects of cancer and discuss how in mammary epithelial cells, the expression of its CK2β regulatory subunit plays a critical role in maintaining an epithelial phenotype through CK2-mediated control of key EMT-related transcription factors. Importantly, decreased CK2β expression in breast tumors is correlated with inefficient phosphorylation and nuclear translocation of Snail1 and Foxc2, ultimately leading to EMT induction. This review highlights the pivotal role played by CK2β in the mammary epithelial phenotype and discusses how a modest alteration in its expression may be sufficient to induce dramatic effects facilitating the early steps in tumor cell dissemination through the coordinated regulation of two key transcription factors.

Cellular inhibitor of apoptosis protein 2 controls human colonic epithelial restitution, migration, and Rac1 activation

Identification of pathways involved in wound healing is important for understanding the pathogenesis of various intestinal diseases. Cellular inhibitor of apoptosis protein 2 (cIAP2) regulates proliferation and migration in nonepithelial cells and is expressed in human colonocytes. The aim of the study was to investigate the role of cIAP2 for wound healing in the normal human colon. Wound tissue was generated by taking rectosigmoidal biopsies across an experimental ulcer in healthy subjects after 5, 24, and 48 h. In experimental ulcers, the expression of cIAP2 in regenerating intestinal epithelial cells (IECs) was increased at the wound edge after 24 h (P < 0.05), returned to normal after reepithelialization, and correlated with the inflammatory reaction in the experimental wounds (P < 0.001). cIAP2 was induced in vitro in regenerating Caco2 IECs after wound infliction (P < 0.01). Knockdown of cIAP2 caused a substantial impairment of the IEC regeneration through inhibition of migration (P < 0.005). cIAP2 overexpression lead to formation of migrating IECs and upregulation of expression of RhoA and Rac1 as well as GTP-activation of Rac1. Transforming growth factor-β1 enhanced the expression of cIAP2 but was not upregulated in wounds in vivo and in vitro. NF-κB and MAPK pathways did not affect cIAP2 expression. cIAP2 is in conclusion a regulator of human intestinal wound healing through enhanced migration along with activation of Rac1, and the findings suggest that cIAP2 could be a future therapeutic target to improve intestinal wound healing.

Mucosal healing in inflammatory bowel diseases: is there a place for nutritional supplementation?

Advanced mucosal healing (MH) after intestinal mucosal inflammation coincides with sustained clinical remission and reduced rates of hospitalization and surgical resection, explaining why MH is increasingly considered as a full therapeutic goal and as an endpoint for clinical trials. Intestinal MH is a complex phenomenon viewed as a succession of steps necessary to restore tissue structure and function. These steps include epithelial cell migration and proliferation, cell differentiation, restoration of epithelial barrier functions, and modulation of cell apoptosis. Few clinical studies have evaluated the needs for specific macronutrients and micronutrients and their effects on intestinal MH, most data having been obtained from animal and cell studies. These data suggest that supplementation with specific amino acids including arginine, glutamine, glutamate, threonine, methionine, serine, proline, and the amino acid-derived compounds, polyamines can favorably influence MH. Short-chain fatty acids, which are produced by the microbiota from undigested polysaccharides and protein-derived amino acids, also exert beneficial effects on the process of intestinal MH in experimental models. Regarding supplementation with lipids, although the effects of ω-3 and ω-6 fatty acids remain controversial, endogenous prostaglandin synthesis seems to be necessary for MH. Finally, among micronutrients, several vitamin and mineral deficiencies with different frequencies have been observed in patients with inflammatory bowel diseases and supplementation with some of them (vitamin A, vitamin D3, vitamin C, and zinc) are presumed to favor MH. Future work, including clinical studies, should evaluate the efficiency of supplementation with combination of dietary compounds as adjuvant nutritional intervention for MH of the inflamed intestinal mucosa.

Autonomous inhibition of apoptosis correlates with responsiveness of colon carcinoma cell lines to ciglitazone

Colorectal cancer is a leading cause of mortality worldwide. Resistance to therapy is common and often results in patients succumbing to the disease. The mechanisms of resistance are poorly understood. Cells basically have two possibilities to survive a treatment with potentially apoptosis-inducing substances. They can make use of their existing proteins to counteract the induced reactions or quickly upregulate protective factors to evade the apoptotic signal. To identify protein patterns involved in resistance to apoptosis, we studied two colorectal adenocarcinoma cell lines with different growth responses to low-molar concentrations of the thiazolidinedione Ciglitazone: HT29 cells underwent apoptosis, whereas SW480 cells increased cell number. Fluorescence detection and autoradiography scans of 2D-PAGE gels were performed in both cell lines to assess protein synthesis and turnover, respectively. To verify the data we performed shotgun analysis using the same treatment procedure as in 2D-experiments. Biological functions of the identified proteins were mainly associated with apoptosis regulation, chaperoning, intrinsic inflammation, and DNA repair. The present study suggests that different growth response of two colorectal carcinoma cell lines after treatment with Ciglitazone results from cell-specific protein synthesis and differences in protein regulation.

Mast cell deficiency exacerbates inflammatory bowel symptoms in interleukin-10-deficient mice

AIM: To test the role of mast cells in gut inflammation and colitis using interleukin (IL)-10-deficient mice as an experimental model.

METHODS: Mast cell-deficient (Kit^W-sh/W-sh) mice were crossbred with IL-10-deficient mice to obtain double knockout (DKO) mice. The growth, mucosal damage and colitis status of DKO mice were compared with their IL-10-deficient littermates.

RESULTS: DKO mice exhibited exacerbated colitis compared with their IL-10-deficient littermates, as shown by increased pathological score, higher myeloperoxidase content, enhanced Th1 type pro-inflammatory cytokines and inflammatory signaling, elevated oxidative stress, as well as pronounced goblet cell loss. In addition, deficiency in mast cells resulted in enhanced mucosal damage, increased gut permeability, and impaired epithelial tight junctions. Mast cell deficiency was also linked to systemic inflammation, as demonstrated by higher serum levels of tumor necrosis factor α and interferon γ in DKO mice than that in IL-10-deficient mice.

CONCLUSION: Mast cell deficiency in IL-10-deficient mice resulted in systematic and gut inflammation, impaired gut barrier function, and severer Th1-mediated colitis when compared to mice with only IL-10-deficiency. Inflammation and impaired gut epithelial barrier function likely form a vicious cycle to worsen colitis in the DKO mice.

Maternal obesity induces gut inflammation and impairs gut epithelial barrier function in nonobese diabetic mice

Impairment of gut epithelial barrier function is a key predisposing factor for inflammatory bowel disease, type 1 diabetes (T1D) and related autoimmune diseases. We hypothesized that maternal obesity induces gut inflammation and impairs epithelial barrier function in the offspring of nonobese diabetic (NOD) mice. Four-week-old female NOD/ShiLtJ mice were fed with a control diet (CON; 10% energy from fat) or a high-fat diet (HFD; 60% energy from fat) for 8 weeks to induce obesity and then mated. During pregnancy and lactation, mice were maintained in their respective diets. After weaning, all offspring were fed the CON diet. At 16 weeks of age, female offspring were subjected to in vivo intestinal permeability test, and then ileum was sampled for biochemical analyses. Inflammasome mediators, activated caspase-1 and mature forms of interleukin (IL)-1β and IL-18 were enhanced in offspring of obese mothers, which was associated with elevated serum tumor necrosis factor α level and inflammatory mediators. Consistently, abundance of oxidative stress markers including catalase, peroxiredoxin-4 and superoxide dismutase 1 was heightened in offspring ileum (P<.05). Furthermore, offspring from obese mothers had a higher intestinal permeability. Morphologically, maternal obesity reduced villi/crypt ratio in the ileum of offspring gut. In conclusion, maternal obesity induced inflammation and impaired gut barrier function in offspring of NOD mice. The enhanced gut permeability in HFD offspring might predispose them to the development of T1D and other gut permeability-associated diseases.

CFTR mutations altering CFTR fragmentation

Most CF (cystic fibrosis) results from deletion of a phenylalanine (F⁵⁰⁸) in the CFTR {CF transmembrane-conductance regulator; ABCC7 [ABC (ATP-binding cassette) sub-family C member 7]} which causes ER (endoplasmic reticulum) degradation of the mutant. Using stably CFTR-expressing BHK (baby-hamster kidney) cell lines we demonstrated that wild-type CTFR and the F508delCFTR mutant are cleaved into differently sized N- and C-terminal-bearing fragments, with each hemi-CFTR carrying its nearest NBD (nucleotide-binding domain), reflecting differential cleavage through the central CFTR R-domain. Similar NBD1-bearing fragments are present in the natively expressing HBE (human bronchial epithelial) cell line. We also observe multiple smaller fragments of different sizes in BHK cells, particularly after F508del mutation (ladder pattern). Trapping wild-type CFTR in the ER did not generate a F508del fragmentation fingerprint. Fragments change their size/pattern again post-mutation at sites involved in CFTR's in vitro interaction with the pleiotropic protein kinase CK2 (S511A in NBD1). The F508del and S511A mutations generate different fragmentation fingerprints that are each unlike the wild-type; yet, both mutants generate new N-terminal-bearing CFTR fragments that are not observed with other CK2-related mutations (S511D, S422A/D and T1471A/D). We conclude that the F508delCFTR mutant is not degraded completely and there exists a relationship between CFTR's fragmentation fingerprint and the CFTR sequence through putative CK2-interactive sites that lie near F508.