CLAN, a Novel Human CED-4-like Gene

Proteins governing cell death form the basis of many normal processes and contribute to the pathogenesis of many diseases when dysregulated. Here we report the cloning of a novel human CED-4-like gene, CLAN, and several of its alternatively spliced isoforms. These caspase-associated recruitment domain (CARD)-containing proteins are expressed at varying degrees in normal human tissues and may contribute to a number of intracellular processes including apoptosis, cytokine processing, and NF-κB activation. The CARD of the CLAN proteins binds a number of other CARD-containing proteins including caspase-1, BCL10, NOD2, and NAC. Once their physiologic functions are uncovered, CLAN proteins may prove to be valuable therapeutic targets.     

Multiple roles of CLAN (caspase-associated recruitment domain, leucine-rich repeat, and NAIP CIIA HET-E, and TP1-containing protein) in the mammalian innate immune response

NAIP CIIA HET-E and TP1 (NACHT) family proteins are involved in sensing intracellular pathogens or pathogen-derived molecules, triggering host defense responses resulting in caspase-mediated processing of proinflammatory cytokines and NF-kappaB activation. Caspase-associated recruitment domain, leucine-rich repeat, and NACHT-containing protein (CLAN), also known as ICE protease-activating factor, belongs to a branch of the NACHT family that contains proteins carrying caspase-associated recruitment domains (CARDs) and leucine-rich repeats (LRRs). By using gene transfer and RNA-interference approaches, we demonstrate in this study that CLAN modulates endogenous caspase-1 activation and subsequent IL-1beta secretion from human macrophages after exposure to LPS, peptidoglycan, and pathogenic bacteria. CLAN was also found to mediate a direct antibacterial effect within macrophages after Salmonella infection and to sensitize host cells to Salmonella-induced cell death through a caspase-1-independent mechanism. These results indicate that CLAN contributes to several biological processes central to host defense, suggesting a prominent role for this NACHT family member in innate immunity.     

Multiple protein domains mediate interaction between Bcl10 and MALT1

Bcl10 and MALT1 are essential mediators of NF-kappaB activation in response to the triggering of a diverse array of transmembrane receptors, including antigen receptors. Additionally, both proteins are translocation targets in MALT lymphoma. Thus, a detailed understanding of the interaction between these mediators is of considerable biological importance. Previous studies have indicated that a 13-amino acid region downstream of the Bcl10 caspase recruitment domain (CARD) is responsible for interacting with the immunoglobulin-like domains of MALT1. We now provide evidence that the death domain of MALT1 and the CARD of Bcl10 also contribute to Bcl10-MALT1 interactions. Although a direct interaction between the MALT1 death domain and Bcl10 cannot be detected via immunoprecipitation, FRET data strongly suggest that the death domain of MALT1 contributes significantly to the association between Bcl10 and MALT1 in T cells in vivo. Furthermore, analysis of point mutants of conserved residues of Bcl10 shows that the Bcl10 CARD is essential for interaction with the MALT1 N terminus. Mutations that disrupt proper folding of the Bcl10 CARD strongly impair Bcl10-MALT1 interactions. Molecular modeling and functional analyses of Bcl10 point mutants suggest that residues Asp(80) and Glu(84) of helix 5 of the Bcl10 CARD directly contact MALT1. Together, these data demonstrate that the association between Bcl10 and MALT1 involves a complex interaction between multiple protein domains. Moreover, the Bcl10-MALT1 interaction is the second reported example of interactions between a CARD and a non-CARD protein region, which suggests that many signaling cascades may utilize CARD interactions with non-CARD domains.     

PDZ domains: the building blocks regulating tumorigenesis

Over 250 PDZ (PSD95/Dlg/ZO-1) domain-containing proteins have been described in the human proteome. As many of these possess multiple PDZ domains, the potential combinations of associations with proteins that possess PBMs (PDZ-binding motifs) are vast. However, PDZ domain recognition is a highly specific process, and much less promiscuous than originally thought. Furthermore, a large number of PDZ domain-containing proteins have been linked directly to the control of processes whose loss, or inappropriate activation, contribute to the development of human malignancies. These regulate processes as diverse as cytoskeletal organization, cell polarity, cell proliferation and many signal transduction pathways. In the present review, we discuss how PBM-PDZ recognition and imbalances therein can perturb cellular homoeostasis and ultimately contribute to malignant progression.     

Molecular cloning and expression analysis of a novel caspase recruitment domain protein (CARD) in common carp Cyprinus carpio L

A novel caspase recruitment domain protein (CARD) was isolated from common carp Cyprinus carpio L. by expressed sequence tag analysis. This gene consist of a 2016 bp open reading frame and untranslated regions, which is putatively translated to a protein of 535 amino acid residues. The gene harbors domains (CARD and Coiled-coil domain), which are conserved in proteins of CARD family. The CARD domain have carp was similar to human CARD9 with 72.4% identity. Expression analysis revealed that CARD gene of carp (carp-CARD) expressed in normal tissues of head kidney, spleen, liver, heart and brain. Here we demonstrated that the expression of carp-CARD increased by cortisol treatment in all the tissues and had a high and long lasting expression in cortisol treated spleen.     

Differential effects of filipin and methyl-beta-cyclodextrin on B cell receptor signaling

The CED4/Apaf-1 family of proteins functions as critical regulators of apoptosis and NF-kappaB signaling pathways. A novel human member of this family, called CARD12, was identified that induces apoptosis when expressed in cells. CARD12 is most similar in structure to the CED4/Apaf-1 family member CARD4, and is comprised of an N-terminal caspase recruitment domain (CARD), a central nucleotide-binding site (NBS), and a C-terminal domain of leucine-rich repeats (LRR). The CARD domain of CARD12 interacts selectively with the CARD domain of ASC, a recently identified proapoptotic protein. In addition, CARD12 coprecipitates caspase-1, a caspase that participates in both apoptotic signaling and cytokine processing. CARD12 may assemble with proapoptotic CARD proteins to coordinate the activation of downstream apoptotic and inflammatory signaling pathways.     

The involvement of the interleukin-1 receptor-associated kinases (IRAKs) in cellular signaling networks controlling inflammation

Innate immunity and inflammation plays a key role in host defense and wound healing. However, Excessive or altered inflammatory processes can contribute to severe and diverse human diseases including cardiovascular disease, diabetes and cancer. The interleukin-1 receptor-associated kinases (IRAKs) are critically involved in the regulation of intracellular signaling networks controlling inflammation. Collective studies indicate that IRAKs are present in many cell types, and can mediate signals from various cell receptors including toll-like-receptors (TLRs). Consequently, diverse downstream signaling processes can be elicited following the activation of various IRAKs. Given the critical and complex roles IRAK proteins play, it is not surprising that genetic variations in human IRAK genes have been found to be linked with various human inflammatory diseases. This review intends to summarize the recent advances regarding the regulations of various IRAK proteins and their cellular functions in mediating inflammatory signaling processes.     

Human CARD4 protein is a novel CED-4/Apaf-1 cell death family member that activates NF-kappaB

The nematode CED-4 protein and its human homolog Apaf-1 play a central role in apoptosis by functioning as direct activators of death-inducing caspases. A novel human CED-4/Apaf-1 family member called CARD4 was identified that has a domain structure strikingly similar to the cytoplasmic, receptor-like proteins that mediate disease resistance in plants. CARD4 interacted with the serine-threonine kinase RICK and potently induced NF-kappaB activity through TRAF-6 and NIK signaling molecules. In addition, coexpression of CARD4 augmented caspase-9-induced apoptosis. Thus, CARD4 coordinates downstream NF-kappaB and apoptotic signaling pathways and may be a component of the host innate immune response.     

Shared and unique functions of the DExD/H-box helicases RIG-I, MDA5, and LGP2 in antiviral innate immunity

The cellular protein retinoic acid-inducible gene I (RIG-I) senses intracellular viral infection and triggers a signal for innate antiviral responses including the production of type I IFN. RIG-I contains a domain that belongs to a DExD/H-box helicase family and exhibits an N-terminal caspase recruitment domain (CARD) homology. There are three genes encoding RIG-I-related proteins in human and mouse genomes. Melanoma differentiation associated gene 5 (MDA5), which consists of CARD and a helicase domain, functions as a positive regulator, similarly to RIG-I. Both proteins sense viral RNA with a helicase domain and transmit a signal downstream by CARD; thus, these proteins share overlapping functions. Another protein, LGP2, lacks the CARD homology and functions as a negative regulator by interfering with the recognition of viral RNA by RIG-I and MDA5. The nonstructural protein 3/4A protein of hepatitis C virus blocks the signaling by RIG-I and MDA5; however, the V protein of the Sendai virus selectively abrogates the MDA5 function. These results highlight ingenious mechanisms for initiating antiviral innate immune responses and the action of virus-encoded inhibitors.     

The human ATP-binding cassette (ABC) transporter superfamily.

The transport of specific molecules across lipid membranes is an essential function of all living organisms and a large number of specific transporters have evolved to carry out this function. The largest transporter gene family is the ATP-binding cassette (ABC) transporter superfamily. These proteins translocate a wide variety of substrates including sugars, amino acids, metal ions, peptides, and proteins, and a large number of hydrophobic compounds and metabolites across extra- and intracellular membranes. ABC genes are essential for many processes in the cell, and mutations in these genes cause or contribute to several human genetic disorders including cystic fibrosis, neurological disease, retinal degeneration, cholesterol and bile transport defects, anemia, and drug response. Characterization of eukaryotic genomes has allowed the complete identification of all the ABC genes in the yeast Saccharomyces cerevisiae, Drosophila, and C. elegans genomes. To date, there are 48 characterized human ABC genes. The genes can be divided into seven distinct subfamilies, based on organization of domains and amino acid homology. Many ABC genes play a role in the maintenance of the lipid bilayer and in the transport of fatty acids and sterols within the body. Here, we review the current knowledge of the human ABC genes, their role in inherited disease, and understanding of the topology of these genes within the membrane.     

A comprehensive interaction study provides a potential domain interaction network of human death domain superfamily proteins

Human death domain superfamily proteins (DDSPs) play important roles in many signaling pathways involved in cell death and inflammation. Disruption or constitutive activation of these DDSP interactions due to inherited gene mutations is closely related to immunodeficiency and/or autoinflammatory diseases; however, responsible gene mutations have not been found in phenotypical diagnosis of these diseases. In this study, we comprehensively investigated the interactions of death-fold domains to explore the signaling network mediated by human DDSPs. We obtained 116 domains of DDSPs and conducted a domain–domain interaction assay of 13,924 reactions in duplicate using amplified luminescent proximity homogeneous assay. The data were mostly consistent with previously reported interactions. We also found new possible interactions, including an interaction between the caspase recruitment domain (CARD) of CARD10 and the tandem CARD–CARD domain of NOD2, which was confirmed by reciprocal co-immunoprecipitation. This study enables prediction of the interaction network of human DDSPs, sheds light on pathogenic mechanisms, and will facilitate identification of drug targets for treatment of immunodeficiency and autoinflammatory diseases.Subject terms: Cell death and immune response, Rheumatic diseases     

Card10 is a novel caspase recruitment domain/membrane-associated guanylate kinase family member that interacts with BCL10 and activates NF-kappa B

BCL10 belongs to the caspase recruitment domain (CARD) family of proteins that regulate apoptosis and NF-kappaB signaling pathways. Analysis of BCL10-deficient mice has revealed that BCL10 mediates NF-kappaB activation by antigen receptors in B and T cells. We recently identified a subclass of CARD proteins (CARD9, CARD11, and CARD14) that may function to connect BCL10 to multiple upstream signaling pathways. We report here that CARD10 is a novel BCL10 interactor that belongs to the membrane-associated guanylate kinase family, a class of proteins that function to organize signaling complexes at plasma membranes. When expressed in cells, CARD10 binds to BCL10 and signals the activation of NF-kappaB through its N-terminal effector CARD domain. We propose that CARD10 functions as a molecular scaffold for the assembly of a BCL10 signaling complex that activates NF-kappaB.     

Discoidin domain receptor 1 interactions with myosin motors contribute to collagen remodeling and tissue fibrosis

Discoidin Domain Receptor (DDR) genes and their homologues have been identified in sponges, worms and flies. These genes code for proteins that are implicated in cell adhesion to matrix proteins. DDRs are now recognized as playing central regulatory roles in several high prevalence human diseases, including invasive cancers, atherosclerosis, and organ fibrosis. While the mechanisms by which DDRs contribute to these diseases are just now being delineated, one of the common themes involves cell adhesion to collagen and the assembly and organization of collagen fibers in the extracellular matrix. In mammals, the multi-functional roles of DDRs in promoting cell adhesion to collagen fibers and in mediating collagen-dependent signaling, suggest that DDRs contribute to multiple pathways of extracellular matrix remodeling, which are centrally important processes in health and disease. In this review we consider that interactions of the cytoplasmic domains of DDR1 with cytoskeletal motor proteins may contribute to matrix remodeling by promoting collagen fiber alignment and compaction. Poorly controlled collagen remodeling with excessive compaction of matrix proteins is a hallmark of fibrotic lesions in many organs and tissues that are affected by infectious, traumatic or chemical-mediated injury. An improved understanding of the mechanisms by which DDRs mediate collagen remodeling and collagen-dependent signaling could suggest new drug targets for treatment of fibrotic diseases.     

Regulation of apoptosis by alternative pre-mRNA splicing

Apoptosis, a phenomenon that allows the regulated destruction and disposal of damaged or unwanted cells, is common to many cellular processes in multicellular organisms. In humans more than 200 proteins are involved in apoptosis, many of which are dysregulated or defective in human diseases including cancer. A large number of apoptotic factors are regulated via alternative splicing, a process that allows for the production of discrete protein isoforms with often distinct functions from a common mRNA precursor. The abundance of apoptosis genes that are alternatively spliced and the often antagonistic roles of the generated protein isoforms strongly imply that alternative splicing is a crucial mechanism for regulating life and death decisions. Importantly, modulation of isoform production of cell death proteins via pharmaceutical manipulation of alternative splicing may open up new therapeutic avenues for the treatment of disease.     

microRNAs – kleine Moleküle ganz groß

microRNAs, regulators of complex phenotypes microRNAs (miRNAs) are small, non‐coding RNAs that regulate a number of biological processes, including development. Due to their mode of action some miRNAs are also causally involved in diseases like cancer. miRNAs bind base‐complementary mRNAs and lead to either degradation of the bound mRNAs or translational repression. Both result in decreased protein levels of the particular target. miRNA selectivity is governed via a very short, just six to seven nucleotides long, ”seed" sequence which is likely to exist in many mRNAs. miRNAs are, therefore, believed to target a larger number of mRNAs, each, leading to the concerted regulation of functionally connected proteins and to thus substantially contribute to phenotypes. We have performed several screenings which suggest that, indeed, many miRNAs regulate a larger number of proteins. However, we also showed that the proteins we tested were regulated by a larger number of miRNAs each. The complexity of miRNA regulation opens new avenues towards reaching a molecular understanding of disease phenotypes via the integrated consideration of coordinated regulations.     

Beneficial health effects of milk and fermented dairy products — Review

Milk is a complex physiological liquid that simultaneously provides nutrients and bioactive components that facilitate the successful postnatal adaptation of the newborn infant by stimulating cellular growth and digestive maturation, the establishment of symbiotic microflora, and the development of gut-associated lymphoid tissues. The number, the potency, and the importance of bioactive compounds in milk and especially in fermented milk products are probably greater than previously thought. They include certain vitamins, specific proteins, bioactive peptides, oligosaccharides, organic (including fatty) acids. Some of them are normal milk components, others emerge during digestive or fermentation processes. Fermented dairy products and probiotic bacteria decrease the absorption of cholesterol. Whey proteins, medium-chain fatty acids and in particular calcium and other minerals may contribute to the beneficial effect of dairy food on body fat and body mass. There has been growing evidence of the role that dairy proteins play in the regulation of satiety, food intake and obesity-related metabolic disorders. Milk proteins, peptides, probiotic lactic acid bacteria, calcium and other minerals can significantly reduce blood pressure. Milk fat contains a number of components having functional properties. Sphingolipids and their active metabolites may exert antimicrobial effects either directly or upon digestion.