The NKG2D Ligands RAE-1δ and RAE-1ε Differ with Respect to Their Receptor Affinity, Expression Profiles and Transcriptional Regulation

BACKGROUND: RAE-1 is a ligand of the activating receptor NKG2D expressed by NK cells, NKT, γδT and some CD8(+)T lymphocytes. RAE-1 is overexpressed in tumor cell lines and its expression is induced after viral infection and genotoxic stress. We have recently demonstrated that RAE-1 is expressed in the adult subventricular zone (SVZ) from C57BL/6 mice. RAE-1 is also expressed in vitro by neural stem/progenitor cells (NSPCs) and plays a non-immune role in cell proliferation. The C57BL/6 mouse genome contains two rae-1 genes, rae-1δ and rae-1ε encoding two different proteins. The goals of this study are first to characterize the in vivo and in vitro expression of each gene and secondly to elucidate the mechanisms underlying their respective expression, which are far from known. PRINCIPAL FINDINGS: We observed that Rae-1δ and Rae-1ε transcripts are differentially expressed according to tissues, pathological conditions and cell lines. Embryonic tissue and the adult SVZ mainly expressed Rae-1δ transcripts. The NSPCs derived from the SVZ also mainly expressed RAE-1δ. The interest of this result is especially related to the observation that RAE-1δ is a weak NKG2D ligand compared to RAE-1ε. On the contrary, cell lines expressed either similar levels of RAE-1δ and RAE-1ε proteins or only RAE-1ε. Since the protein expression correlated with the level of transcripts for each rae-1 gene, we postulated that transcriptional regulation is one of the main processes explaining the difference between RAE-1δ and RAE-1ε expression. We indeed identified two different promoter regions for each gene: one mainly involved in the control of rae-1δ gene expression and the other in the control of rae-1ε expression. CONCLUSIONS/SIGNIFICANCE: RAE-1δ and RAE-1ε differ with respect to their function and the control of their expression. Immune function would be mainly exerted by RAE-1ε and non-immune function by RAE-1δ

Amino acid sequence of the active site of human serum cholinesterase from usual, atypical, and atypical-silent genotypes

Active-site tryptic peptides were isolated from three genetic types of human serum cholinesterase. The active-site peptide was identified by labeling the active-site serine with [ 3 H] diisopropylfluorophosphate. Peptides were purified by high-performance liquid chromatography. Amino acid composition and sequence analysis showed that the peptide from the usual genotype contained 29 residues with the sequence Ser-Val-Thr-Leu-Phe-Gly-Glu-Ser-Ala-Gly-Ala-Ala-Ser-Val-Ser-Leu-His-Leu-Leu-Ser-Pro-Gly-Ser-His-Ser-Leu-Phe-Thr-Arg. The active-site serine was the eighth residue from the N- terminal. The peptide containing the active-site serine from the atypical genotype contained 22 residues with the sequence Ser-Val-Thr-Leu-Phe-Gly-Glu-Ser-Ala-Gly-Ala-Ala-Ser-Val-Ser-Leu-His-Leu-Leu-Ser-Pro-Gly. The peptide from the atypical-silent genotype contained eight residues with the sequence Gly-Glu-Ser-Ala-Gly-Ala-Ala-Ser. Thus, the sequences of the atypical and atypical-silent active-site peptides were identical to the corresponding portions of the usual peptide.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44153/1/10528_2004_Article_BF00499101.pd

Human Herpesvirus 8 (HHV8) Sequentially Shapes the NK Cell Repertoire during the Course of Asymptomatic Infection and Kaposi Sarcoma

The contribution of innate immunity to immunosurveillance of the oncogenic Human Herpes Virus 8 (HHV8) has not been studied in depth. We investigated NK cell phenotype and function in 70 HHV8-infected subjects, either asymptomatic carriers or having developed Kaposi's sarcoma (KS). Our results revealed substantial alterations of the NK cell receptor repertoire in healthy HHV8 carriers, with reduced expression of NKp30, NKp46 and CD161 receptors. In addition, down-modulation of the activating NKG2D receptor, associated with impaired NK-cell lytic capacity, was observed in patients with active KS. Resolution of KS after treatment was accompanied with restoration of NKG2D levels and NK cell activity. HHV8-latently infected endothelial cells overexpressed ligands of several NK cell receptors, including NKG2D ligands. The strong expression of NKG2D ligands by tumor cells was confirmed in situ by immunohistochemical staining of KS biopsies. However, no tumor-infiltrating NK cells were detected, suggesting a defect in NK cell homing or survival in the KS microenvironment. Among the known KS-derived immunoregulatory factors, we identified prostaglandin E2 (PGE2) as a critical element responsible for the down-modulation of NKG2D expression on resting NK cells. Moreover, PGE2 prevented up-regulation of the NKG2D and NKp30 receptors on IL-15-activated NK cells, and inhibited the IL-15-induced proliferation and survival of NK cells. Altogether, our observations are consistent with distinct immunoevasion mechanisms that allow HHV8 to escape NK cell responses stepwise, first at early stages of infection to facilitate the maintenance of viral latency, and later to promote tumor cell growth through suppression of NKG2D-mediated functions. Importantly, our results provide additional support to the use of PGE2 inhibitors as an attractive approach to treat aggressive KS, as they could restore activation and survival of tumoricidal NK cells

Regulation of immune cell function and differentiation by the NKG2D receptor

NKG2D is one of the most intensively studied immune receptors of the past decade. Its unique binding and signaling properties, expression pattern, and functions have been attracting much interest within the field due to its potent antiviral and anti-tumor properties. As an activating receptor, NKG2D is expressed on cells of the innate and adaptive immune system. It recognizes stress-induced MHC class I-like ligands and acts as a molecular sensor for cells jeopardized by viral infections or DNA damage. Although the activating functions of NKG2D have been well documented, recent analysis of NKG2D-deficient mice suggests that this receptor may have a regulatory role during NK cell development. In this review, we will revisit known aspects of NKG2D functions and present new insights in the proposed influence of this molecule on hematopoietic differentiation

Atopy Is Inversely Related to Schistosome Infection Intensity: A Comparative Study in Zimbabwean Villages with Distinct Levels of <i>Schistosoma haematobium</i> Infection

This is the peer-reviewed but unedited manuscript version of the following article:Rujeni, N., et al. (2012). "Atopy Is Inversely Related to Schistosome Infection Intensity: A Comparative Study in Zimbabwean Villages with Distinct Levels of Schistosoma haematobium Infection." International Archives of Allergy and Immunology 158(3): 288-298.. The final, published version is available at http://www.karger.com/DOI: 10.1159/000332949e World Health Organization (Grant No. RPC264), The Welcome Trust (Grant No. WT082028MA), the University of Edinburgh and the government of Rwanda

NK cells and cancer: you can teach innate cells new tricks

Natural killer (NK) cells are the prototype innate lymphoid cells endowed with potent cytolytic function that provide host defence against microbial infection and tumours. Here, we review evidence for the role of NK cells in immune surveillance against cancer and highlight new therapeutic approaches for targeting NK cells in the treatment of cancer

An N-terminally truncated form of cyclic GMP–dependent protein kinase Iα (PKG Iα) is monomeric and autoinhibited and provides a model for activation

The type I cGMP-dependent protein kinases (PKG I) serve essential physiological functions, including smooth muscle relaxation, cardiac remodeling, and platelet aggregation. These enzymes form homodimers through their N-terminal dimerization domains, a feature implicated in regulating their cooperative activation. Previous investigations into the activation mechanisms of PKG I isoforms have been largely influenced by structures of the cAMP-dependent protein kinase (PKA). Here, we examined PKG I activation by cGMP and cAMP by engineering a monomeric form that lacks N-terminal residues 1-53 (53). We found that the construct exists as a monomer as assessed by whole-protein MS, size-exclusion chromatography, and small-angle X-ray scattering (SAXS). Reconstruction of the SAXS 3D envelope indicates that 53 has a similar shape to the heterodimeric RI-C complex of PKA. Moreover, we found that the 53 construct is autoinhibited in its cGMP-free state and can bind to and be activated by cGMP in a manner similar to full-length PKG I as assessed by surface plasmon resonance (SPR) spectroscopy. However, we found that the 53 variant does not exhibit cooperative activation, and its cyclic nucleotide selectivity is diminished. These findings support a model in which, despite structural similarities, PKG I activation is distinct from that of PKA, and its cooperativity is driven by in trans interactions between protomers.United States Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences [DE-AC02-76SF00515]; DOE Office of Biological and Environmental Research; National Institute of General Medical Sciences at the National Institutes of Health (NIH) [P41GM103393]; Centers of Biomedical Research Excellence (COBRE) from the NIGMS, National Institutes of Health [P30-GM118228]12 month embargo; published online: 30 March 2018This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]