A heterozygous RAB27A mutation causes delayed cytolytic granule polarization and hemophagocytic lymphohistiocytosis in 2 unrelated teenagers

Frequently fatal, primary hemophagocytic lymphohistiocytosis (HLH) occurs in infancy resulting from homozygous mutations in natural killer (NK) and CD8 T cell cytolytic pathway genes. Secondary HLH presents after infancy and may be associated with heterozygous mutations in HLH genes. We report 2 unrelated teenagers with HLH and an identical heterozygous RAB27A mutation (259 G>C). The contribution of this Rab27A missense (A87P) mutation on NK cell cytotoxicity was studied by cloning it into a lentiviral expression vector prior to introduction into the human NK-92 cell line. NK cell degranulation (CD107a expression), target cell conjugation, and K562 target cell lysis was compared between mutant and wild-type (WT) transduced NK-92 cells. Polarization of granzyme B to the immunologic synapse and interaction of mutant Rab27A (A87P) with Munc13-4 were explored by confocal microscopy and proximity ligation assay (PLA), respectively. Over-expression of the RAB27A mutation had no effect on cell conjugate formation between the NK and target cells but decreased NK cell cytolytic activity and degranulation. Moreover, the mutant Rab27A protein was predicted to disrupt binding to WT Munc13-4 by crystal structure modelling, and decreased interaction of Rab27A (A87P) with WT Munc13-4 was shown by PLA in situ and by co-immunoprecipiation in vitro. Finally, Rab27A (A87P) over-expression in NK-92 cells delayed granzyme B polarization toward the immunologic synapse, as noted by confocal microscopy, with a resulting increase in interferon-γ production, a cytokine responsible for HLH. This heterozygous RAB27A mutation blurs the genetic distinction between primary and secondary HLH by contributing to HLH via a partial dominant-negative effect.

The susceptibility of primary cultured rhesus macaque kidney epithelial cells to rhesus cytomegalovirus strains

Kidney epithelial cells are common targets for human and rhesus cytomegalovirus (HCMV and RhCMV) in vivo, and represent an important reservoir for long-term CMV shedding in urine. To better understand the role of kidney epithelial cells in primate CMV natural history, primary cultures of rhesus macaque kidney epithelial cells (MKE) were established and tested for infectivity by five RhCMV strains, including two wild-type strains (UCD52 and UCD59) and three strains containing different coding contents in UL/b'. The latter strains included 180.92 [containing an intact RhUL128-RhUL130-R hUL131 (RhUL128L) locus but deleted for the UL/b' RhUL148-rh167-loci], 68-1 (RhUL128L-defective and fibroblast-tropic) and BRh68-1.2 (the RhUL128L-repaired version of 68-1). As demonstrated by RhCMV cytopathic effect, plaque formation, growth kinetics and early virus entry, we showed that MKE were differentially susceptible to RhCMV infection, related to UL/b' coding contents of the different strains. UCD52 and UCD59 replicated vigorously in MKE, 68-1 replicated poorly, and 180.92 grew with intermediate kinetics. Reconstitution of RhUL128L in 68-1 (BRh68-1.2) restored its replication efficiency in MKE as compared to UCD52 and UCD59, consistent with the essential role of UL128L for HCMV epithelial tropism. Further analysis revealed that the UL/b' UL148-rh167-loci deletion in 180.92 impaired RhUL132 (rh160) expression. Given that 180.92 retains an intact RhUL128L, but genetically or functionally lacks genes from RhUL132 (rh160) to rh167 in UL/b', its attenuated infection efficiency indicated that, along with RhUL128L, an additional protein(s) encoded within the UL/b' RhUL132 (rh160)-rh167 region (potentially, RhUL132 and/or RhUL148) is indispensable for efficient replication in MKE.

A Heterozygous RAB27A Mutation Associated with Delayed Cytolytic Granule Polarization and Hemophagocytic Lymphohistiocytosis

Frequently fatal, primary hemophagocytic lymphohistiocytosis (HLH) occurs in infancy resulting from homozygous mutations in NK and CD8 T cell cytolytic pathway genes. Secondary HLH presents after infancy and may be associated with heterozygous mutations in HLH genes. We report two unrelated teenagers with HLH and an identical heterozygous RAB27A mutation (c.259G→C). We explore the contribution of this Rab27A missense (p.A87P) mutation on NK cell cytolytic function by cloning it into a lentiviral expression vector prior to introduction into the human NK-92 cell line. NK cell degranulation (CD107a expression), target cell conjugation, and K562 target cell lysis was compared between mutant- and wild-type-transduced NK-92 cells. Polarization of granzyme B to the immunologic synapse and interaction of mutant Rab27A (p.A87P) with Munc13-4 were explored by confocal microscopy and proximity ligation assay, respectively. Overexpression of the RAB27A mutation had no effect on cell conjugate formation between the NK and target cells but decreased NK cell cytolytic activity and degranulation. Moreover, the mutant Rab27A protein decreased binding to Munc13-4 and delayed granzyme B polarization toward the immunologic synapse. This heterozygous RAB27A mutation blurs the genetic distinction between primary and secondary HLH by contributing to HLH via a partial dominant-negative effect.

Cytokine Activation by Antibody Fragments Targeted to Cytokine-Receptor Signaling Complexes

Exogenous cytokine therapy can induce systemic toxicity, which might be prevented by activating endogenously produced cytokines in local cell niches. Here we developed antibody-based activators of cytokine signaling (AcCS), which recognize cytokines only when they are bound to their cell surface receptors. AcCS were developed for type I interferons (IFNs), which induce cellular activities by binding to cell surface receptors IFNAR1 and IFNAR2. As a potential alternative to exogenous IFN therapy, AcCS were shown to potentiate the biological activities of natural IFNs by ∼100-fold. Biochemical and structural characterization demonstrates that the AcCS stabilize the IFN-IFNAR2 binary complex by recognizing an IFN-induced conformational change in IFNAR2. Using IFN mutants that disrupt IFNAR1 binding, AcCS were able to enhance IFN antiviral potency without activating antiproliferative responses. This suggests AcCS can be used to manipulate cytokine signaling for basic science and possibly for therapeutic applications.

Hydrocarbons preserved in a ~2.7 Ga outcrop sample from the Fortescue Group, Pilbara Craton, Western Australia

The hydrocarbons preserved in an Archean rock were extracted, and their composition and distribution in consecutive slices from the outside to the inside of the rock were examined. The 2.7 Ga rock was collected from the Fortescue Group in the Pilbara region, Western Australia. The bitumen I (solvent-extracted rock) and bitumen II (solvent-extracted hydrochloric acid-treated rock) fractions have different hydrocarbon compositions. Bitumen I contains only trace amounts of aliphatic hydrocarbons and virtually no aromatic hydrocarbons. In contrast, bitumen II contains abundant aliphatic and aromatic hydrocarbons. The difference seems to reflect the weathering history and preservational environment of the investigated rock. Aliphatic hydrocarbons in bitumen I are considered to be mainly from later hydrocarbon inputs, after initial deposition and burial, and are therefore not indigenous. The lack of aromatic hydrocarbons in bitumen I suggests a severe weathering environment since uplift and exposure of the rock at the Earth's surface in the Cenozoic. On the other hand, the high abundance of aromatic hydrocarbons in bitumen II suggests that bitumen II hydrocarbons have been physically isolated from removal by their encapsulation within carbonate minerals. The richness of aromatic hydrocarbons and the relative scarcity of aliphatic hydrocarbons may reflect the original compositions of organic materials biosynthesised in ancient organisms in the Archean era, or the high thermal maturity of the rock. Cyanobacterial biomarkers were observed in the surficial slices of the rock, which may indicate that endolithic cyanobacteria inhabited the surface outcrop. The distribution of aliphatic and aromatic hydrocarbons implies a high thermal maturity, which is consistent with the lack of any specific biomarkers, such as hopanes and steranes, and the prehnite-pumpellyite facies metamorphic grade.

Production and characterization of thirteen human type-I interferon-α subtypes

Thirteen human interferon-α (IFNα) subtypes were expressed in Escherichiacoli and purified using an N-terminal affinity tag from the prodomain of subtilisin. IFNα subtypes were expressed in soluble form and purified from cell lysates or refolded and purified from inclusion bodies. Proteins produced by either protocol exhibited biological activities equal to or greater than commercially prepared IFNα preparations. The IFNαs were used to produce an anti-IFNα16 antibody (MAb-1B12) that specifically neutralized the biological activity of IFNα16, but not the 12 other IFNαs. Using MAb-1B12, and a previously generated IFNAR1/IFNAR2-FChk heterodimer, an assay was developed to determine total type I IFN biological activity and IFNα16-derived biological activity in an unknown sample.

Very early onset inflammatory bowel disease associated with aberrant trafficking of IL-10R1 and cure by T cell replete haploidentical bone marrow transplantation

PURPOSE

Loss-of-function mutations in IL10 and IL10R cause very early onset inflammatory bowel disease (VEO-IBD). Here, we investigated the molecular pathomechanism of a novel intronic IL10RA mutation and describe a new therapeutic approach of T cell replete haploidentical hematopoietic stem cell transplantation (HSCT).

METHODS

Clinical data were collected by chart review. Genotypes of IL10 and IL10R genes were determined by Sanger sequencing. Expression and function of mutated IL-10R1 were assessed by quantitative PCR, Western blot analysis, enzyme-linked immunosorbent assays, confocal microscopy, and flow cytometry.

RESULTS

We identified a novel homozygous point mutation in intron 3 of the IL10RA (c.368-10C > G) in three related children with VEO-IBD. Bioinformatical analysis predicted an additional 3' splice site created by the mutation. Quantitative PCR analysis showed normal mRNA expression of mutated IL10RA. Sequencing of the patient's cDNA revealed an insertion of the last nine nucleotides of intron 3 as a result of aberrant splicing. Structure-based modeling suggested misfolding of mutated IL-10R1. Western blot analysis demonstrated a different N-linked glycosylation pattern of mutated protein. Immunofluorescence and FACS analysis revealed impaired expression of mutated IL-10R1 at the plasma membrane. In the absence of HLA-identical donors, T cell replete haploidentical HSCT was successfully performed in two patients.

CONCLUSIONS

Our findings expand the spectrum of IL10R mutations in VEO-IBD and emphasize the need for genetic diagnosis of mutations in conserved non-coding sequences of candidate genes. Transplantation of haploidentical stem cells represents a curative therapy in IL-10R-deficient patients, but may be complicated by non-engraftment.

The old but new IgM Fc receptor (FcμR)

IgM is the first Ig isotype to appear during phylogeny, ontogeny and the immune response. The importance of both pre-immune "natural" and antigen-induced "immune" IgM antibodies in immune responses to pathogens and self-antigens has been established by studies of mutant mice deficient in IgM secretion. Effector proteins interacting with the Fc portion of IgM, such as complement and complement receptors, have thus far been proposed, but fail to fully account for the IgM-mediated immune protection and regulation of immune responses. Particularly, the role of the Fc receptor for IgM (FcμR) in such effector functions has not been explored until recently. We have identified an authentic FcμR in humans using a functional cloning strategy and subsequently in mice by RT-PCR and describe here its salient features and the immunological consequences of FcμR deficiency in mice. Since the FcμR we cloned was identical to Toso or Fas inhibitory molecule 3 (FAIM3), there have been spirited debates regarding the real function of FcμR/Toso/FAIM3 and we will also comment on this topic.

Kinetic analysis of cytokine-mediated receptor assembly using engineered FC heterodimers

A method for analyzing ligand-receptor binding kinetics is described, which is based on an engineered FC domain (FChk) that forms a covalent heterodimer. To validate the system, the type I IFN receptors (IFNAR1 and IFNAR2) were expressed as IFNAR1-FChk, IFNAR2-FCkh, and IFNAR1/IFNAR2-FChk fusion proteins. Surface plasmon resonance (SPR) analysis of binary IFNα2a/IFNAR interactions confirmed prior affinity measurements, while the affinity of the IFNα2a/IFNAR1/IFNAR2-FChk interaction reproduced the affinity of IFNα2a binding to living cells. In cellular assays, IFNAR1/IFNAR2-FChk potently neutralized IFNα2a bioactivity with an inhibitory concentration equivalent to the KD measured by SPR. These studies suggest that FChk provides a simple reagent to evaluate the binding kinetics of multiple ligand-receptor signaling systems that control cell growth, development, and immunity.

Epstein-Barr virus IL-10 engages IL-10R1 by a two-step mechanism leading to altered signaling properties

Human interleukin-10 (hIL-10) is a pleiotropic cytokine that is able to suppress or activate cellular immune responses to protect the host from invading pathogens. Epstein-Barr virus (EBV) encodes a viral IL-10 (ebvIL-10) in its genome that has retained the immunosuppressive activities of hIL-10 but lost the ability to induce immunostimulatory activities on some cells. These functional differences are at least partially due to the ∼1000-fold difference in hIL-10 and ebvIL-10 binding affinity for the IL-10R1·IL-10R2 cell surface receptors. Despite weaker binding to IL-10R1, ebvIL-10 is more active than hIL-10 in inducing B-cell proliferation. To explore this counterintuitive observation further, a series of monomeric and dimeric ebvIL-10·hIL-10 chimeric proteins were produced and characterized for receptor binding and cellular proliferation on TF-1/hIL-10R1 cells that express high levels of the IL-10R1 chain. On this cell line, monomeric chimeras elicited cell proliferation in accordance with how tightly they bound to the IL-10R1 chain. In contrast, dimeric chimeras exhibiting the highest affinity for IL-10R1 exhibited reduced proliferative activity. These distinct activity profiles are correlated with kinetic analyses that reveal that the ebvIL-10 dimer is impaired in its ability to form a 1:2 ebvIL-10·IL-10R1 complex. As a result, the ebvIL-10 dimer functions like a monomer at low IL-10R1 levels, which prevents efficient signaling. At high IL-10R1 levels, the ebvIL-10 dimer is able to induce signaling responses greater than hIL-10. Thus, the ebvIL-10 dimer scaffold is essential to prevent activation of cells with low IL-10R1 levels but to maintain or enhance activity on cells with high IL-10R1 levels.

Purification, crystallization and preliminary X-ray diffraction analysis of the IL-20-IL-20R1-IL-20R2 complex

Interleukin-20 (IL-20) is an IL-10-family cytokine that regulates innate and adaptive immunity in skin and other tissues. In addition to protecting the host from various external pathogens, dysregulated IL-20 signaling has been shown to contribute to the pathogenesis of human psoriasis. IL-20 signals through two cell-surface receptor heterodimers, IL-20R1-IL-20R2 and IL-22R1-IL-20R2. In this report, crystals of the IL-20-IL-20R1-IL-20R2 ternary complex have been grown from polyethylene glycol solutions. The crystals belonged to space group P4(1)2(1)2 or P4(3)2(1)2, with unit-cell parameters a = 111, c = 135 Å, and diffracted X-rays to 3 Å resolution. The crystallographic asymmetric unit contains one IL-20-IL-20R1-IL-20R2 complex, corresponding to a solvent content of approximately 54%.

Molecular assessment of UVC radiation-induced DNA damage repair in the stromatolitic halophilic archaeon, Halococcus hamelinensis

The halophilic archaeon Halococcus hamelinensis was isolated from living stromatolites in Shark Bay, Western Australia, that are known to be exposed to extreme conditions of salinity, desiccation, and UV radiation. Modern stromatolites are considered analogues of very early life on Earth and thus inhabitants of modern stromatolites, and Hcc. hamelinensis in particular, are excellent candidates to examine responses to high UV radiation. This organism was exposed to high dosages (up to 500 J/m(2)) of standard germicidal UVC (254 nm) radiation and overall responses such as survival, thymine-thymine cyclobutane pyrimidine dimer formation, and DNA repair have been assessed. Results show that Hcc. hamelinensis is able to survive high UVC radiation dosages and that intact cells give an increased level of DNA protection over purified DNA. The organism was screened for the bacterial-like nucleotide excision repair (NER) genes uvrA, uvrB, uvrC, as well as for the photolyase phr2 gene. All four genes were discovered and changes in the expression levels of those genes during repair in either light or dark were investigated by means of quantitative Real-Time (qRT) PCR. The data obtained and presented in this study show that the uvrA, uvrB, and uvrC genes were up-regulated during both repair conditions. The photolyase phr2 was not induced during dark repair, yet showed a 20-fold increase during repair in light conditions. The data presented is the first molecular study of different repair mechanisms in the genus Halococcus following exposure to high UVC radiation levels.

Interleukin-26: an IL-10-related cytokine produced by Th17 cells

IL-26 is classified as a member of the IL-10 cytokine family because it has limited sequence homology to IL-10 and the IL-10-related cytokines. The human IL-26 gene, IL26, is located on chromosome 12q15 between the genes for two other important class-2 cytokines, IFNG (IFN-γ) and IL22 (IL-22). IL-26 is often co-expressed with IL-22 by activated T cells, especially Th17 cells. It signals through a heterodimeric receptor complex composed of the IL-20R1 and IL-10R2 chains. IL-26 receptors are primarily expressed on non-hematopoietic cell types, particularly epithelial cells. Signaling through IL-26 receptor complexes results in the activation of STAT1 and STAT3 with subsequent induction of IL-26-responsive genes. The biological functions of IL-26 have only begun to be defined.

Substitution of adenovirus serotype 3 hexon onto a serotype 5 oncolytic adenovirus reduces factor X binding, decreases liver tropism, and improves antitumor efficacy

Following intravascular delivery, an important route of administration for many clinical applications, the liver is the predominant site of adenovirus serotype 5 (Ad5) sequestration, thereby posing a risk of toxicity. In this regard, it has recently been shown that the Ad5 capsid binds to the blood coagulation factor X (FX) via the Ad5 hexon protein. This interaction mediates the majority of Ad5 liver transduction. Patient FX levels can be diminished by the administration of warfarin, a vitamin K inhibitor in the liver that decreases FX production; however, warfarin is a potent anticoagulant and can have a number of undesired side effects. Therefore, genetic modification of the virus to ablate FX binding is the preferred approach. Modifications of the hexon protein, specifically within the hypervariable 5 (HVR5) and 7 (HVR7) regions, have produced Ad5 vectors that show minimal liver sequestration. Our laboratory has pioneered adenovirus hexon modifications, including insertion of peptide ligands into the hypervariable regions and substitution of the adenovirus hexon with hexon proteins from alternate serotypes. Substitution of the adenovirus serotype 3 (Ad3) hexon protein onto the Ad5 capsid has been further characterized with regard to its interaction with FX and incorporated into an infectivity-enhanced conditionally replicative adenovirus (CRAd). In vitro evaluation of these hexon-modified vectors showed decreased binding to FX and decreased cell transduction via FX-mediated pathways. Furthermore, in vivo biodistribution studies in mice exhibited a decrease in liver sequestration. With the use of xenograft tumor models, the antitumor efficacy of the hexon-modified CRAds was enhanced over nonmodified controls.

Cytokine-receptor interactions as drug targets

Cytokines are essential proteins that exert potent control over entire cell populations to fight infections and other pathologies, but can by themselves cause disease. Therefore, cytokine-related drugs act either by stimulating or blocking their activities. Our knowledge of the structures of cytokine-receptor complexes, the biophysical basis of their binding, and their mode of biological activation has substantially increased in recent years. This knowledge has been translated into new drugs and drug candidates. This review summarizes our current understanding of the receptor-mediated activity of cytokines, their relation to health and disease, and the agents in use to activate and block their actions.

Siliceous algal and bacterial stromatolites in hot spring and geyser effluents of yellowstone national park

Growing algal and bacterial stromatolites composed of nearly amorphous silica occur around hot springs and geysers in Yellowstone National Park, Wyoming. Some Precambrian stromatolites may be bacterial rather than algal, which has important implications in atmospheric evolution, since bacterial photo-synthesis does not release oxygen. Conophyton stromatolites were thought to have become extinct at the end of the Precambrian, but are still growing in hot spring effluents.

Structure and mechanism of receptor sharing by the IL-10R2 common chain

IL-10R2 is a shared cell surface receptor required for the activation of five class 2 cytokines (IL-10, IL-22, IL-26, IL-28, and IL-29) that play critical roles in host defense. To define the molecular mechanisms that regulate its promiscuous binding, we have determined the crystal structure of the IL-10R2 ectodomain at 2.14 A resolution. IL-10R2 residues required for binding were identified by alanine scanning and used to derive computational models of IL-10/IL-10R1/IL-10R2 and IL-22/IL-22R1/IL-10R2 ternary complexes. The models reveal a conserved binding epitope that is surrounded by two clefts that accommodate the structural and chemical diversity of the cytokines. These results provide a structural framework for interpreting IL-10R2 single nucleotide polymorphisms associated with human disease.

A docking model based on mass spectrometric and biochemical data describes phage packaging motor incorporation

The molecular mechanism of scaffolding protein-mediated incorporation of one and only one DNA packaging motor/connector dodecamer at a unique vertex during lambdoid phage assembly has remained elusive because of the lack of structural information on how the connector and scaffolding proteins interact. We assembled and characterized a phi29 connector-scaffolding complex, which can be incorporated into procapsids during in vitro assembly. Native mass spectrometry revealed that the connector binds at most 12 scaffolding molecules, likely organized as six dimers. A data-driven docking model, using input from chemical cross-linking and mutagenesis data, suggested an interaction between the scaffolding protein and the exterior of the wide domain of the connector dodecamer. The connector binding region of the scaffolding protein lies upstream of the capsid binding region located at the C terminus. This arrangement allows the C terminus of scaffolding protein within the complex to both recruit capsid subunits and mediate the incorporation of the single connector vertex.

Structure of IL-22 bound to its high-affinity IL-22R1 chain

IL-22 is an IL-10 family cytokine that initiates innate immune responses against bacterial pathogens and contributes to immune disease. IL-22 biological activity is initiated by binding to a cell-surface complex composed of IL-22R1 and IL-10R2 receptor chains and further regulated by interactions with a soluble binding protein, IL-22BP, which shares sequence similarity with an extracellular region of IL-22R1 (sIL-22R1). IL-22R1 also pairs with the IL-20R2 chain to induce IL-20 and IL-24 signaling. To define the molecular basis of these diverse interactions, we have determined the structure of the IL-22/sIL-22R1 complex. The structure, combined with homology modeling and surface plasmon resonance studies, defines the molecular basis for the distinct affinities and specificities of IL-22 and IL-10 receptor chains that regulate cellular targeting and signal transduction to elicit effective immune responses.

Crystallization and preliminary X-ray diffraction analysis of human IL-22 bound to the extracellular IL-22R1 chain

Interleukin-22 (IL-22) is a potent mediator of cellular inflammatory responses. Crystals of IL-22 bound to the extracellular high-affinity cell-surface receptor sIL-22R1 have been grown from polyethylene glycol solutions. Crystals suitable for X-ray diffraction analysis were only obtained with mutants of IL-22 and sIL-22R1 that removed the N-linked glycosylation sites found in the wild-type amino-acid sequences. The crystals belonged to space group P2(1), with unit-cell parameters a = 50.43, b = 76.33, c = 114.92 A, beta = 92.45 degrees , and diffracted X-rays to 3.2 A resolution. The crystallographic asymmetric unit contained two IL-22-sIL-22R1 complexes, corresponding to a solvent content of approximately 52%.

Lysis efficiency of standard DNA extraction methods for Halococcus spp. in an organic rich environment

The extraction of nucleic acids from a given environment marks a crucial and essential starting point in any molecular investigation. Members of Halococcus spp. are known for their rigid cell walls, and are thus difficult to lyse and could potentially be overlooked in an environment. Furthermore, the lack of a suitable lysis method hinders subsequent molecular analysis. The effects of six different DNA extraction methods were tested on Halococcus hamelinensis, Halococcus saccharolyticus and Halobacterium salinarum NRC-1 as well as on an organic rich, highly carbonated sediment from stromatolites spiked with Halococcus hamelinensis. The methods tested were based on physical disruption (boiling and freeze/thawing), chemical lysis (Triton X-100, potassium ethyl xanthogenate (XS) buffer and CTAB) and on enzymatic lysis (lysozyme). Results showed that boiling and freeze/thawing had little effect on the lysis of both Halococcus strains. Methods based on chemical lysis (Triton X-100, XS-buffer, and CTAB) showed the best results, however, Triton X-100 treatment failed to produce visible DNA fragments. Using a combination of bead beating, chemical lysis with lysozyme, and thermal shock, lysis of cells was achieved however DNA was badly sheared. Lysis of cells and DNA extraction of samples from spiked sediment proved to be difficult, with the XS-buffer method indicating the best results. This study provides an evaluation of six commonly used methods of cell lysis and DNA extraction of Halococcus spp., and the suitability of the resulting DNA for molecular analysis.

BiP/GRP78 is an intracellular target for MDA-7/IL-24 induction of cancer-specific apoptosis

Melanoma differentiation-associated gene-7/interleukin-24 (mda-7/IL-24) is a unique member of the IL-10 gene family that induces cancer-selective growth suppression and apoptosis in a wide spectrum of human cancers in cell culture and animal models. Additionally, recent clinical trials confirm safety and document significant clinical activity of mda-7/IL-24 in patients with diverse solid cancers and melanomas. Despite intensive study the molecular basis of tumor-cell selectivity of mda-7/IL-24 is not well characterized. Using deletion analysis, a specific mutant of MDA-7/IL-24, M4, consisting of amino acids 104 to 206, is described that retains the cancer-specific growth-suppressive and apoptosis-inducing properties of the full-length protein. Employing rationally designed mutational analysis, we show that MDA-7/IL-24 and M4 physically interact with BiP/GRP78 through their C and F helices, localize in the endoplasmic reticulum, and activate p38 MAPK and GADD gene expression, culminating in cancer-selective apoptosis. These studies provide novel mechanistic insights into the discriminating antitumor activity of MDA-7/IL-24 by elucidating BiP/GRP78 as a defined intracellular target of action and present an unparalleled opportunity to develop improved therapeutic versions of this cancer-specific apoptosis-inducing cytokine.

Isolation of flagellated bacteria implicated in Crohn's disease

BACKGROUND

Serologic expression cloning has identified flagellins of the intestinal microbiota as immunodominant antigens in experimental colitis in mice and in individuals with Crohn's disease (CD). The present study was done to identify the microbial source of such flagellins.

METHODS

Using a variety of isolation and culture approaches, a number of previously unknown flagellated bacteria were isolated. Based on 16S ribosomal DNA sequences, these bacteria fall into the family Lachnospiraceae of the phylum Firmicutes.

RESULTS

Serum IgG from patients with CD and from mice with colitis reacted to the flagellins of these bacteria, and only their flagellins, whereas serum IgG from controls did not. The sequence of these flagellins demonstrate conserved amino- and carboxy-terminal domains that cluster phylogenetically and have a predicted 3D structure similar to Salmonella fliC, including an intact TLR5 binding site. The flagellin of 1 of these bacteria was likely O-glycosylated.

CONCLUSIONS

The conserved immune response in both mouse and human to these previously unknown flagellins of the microbiota indicate that they play an important role in host-microbe interactions in the intestine.

Protein crystallization

X-ray crystallography is a powerful method for obtaining the three-dimensional structures of biological macromolecules and macromolecular complexes. Improvements in protein production, crystallization, data collection, as well as structure solution and refinement methods have brought the field to the verge of rapid high-throughput genomic scale structure determination. The major bottle neck to this process remains protein production and crystallization. This chapter describes essential information on standard protein production and crystallization methods and ongoing efforts to perform this work using high-throughput robotics.