Human cytomegalovirus UL141 promotes efficient downregulation of the natural killer cell activating ligand CD112

Human cytomegalovirus (HCMV) UL141 induces protection against natural killer cell-mediated cytolysis by downregulating cell surface expression of CD155 (nectin-like molecule 5; poliovirus receptor), a ligand for the activating receptor DNAM-1 (CD226). However, DNAM-1 is also recognized to bind a second ligand, CD112 (nectin-2). We now show that HCMV targets CD112 for proteasome-mediated degradation by 48 h post-infection, thus removing both activating ligands for DNAM-1 from the cell surface during productive infection. Significantly, cell surface expression of both CD112 and CD155 was restored when UL141 was deleted from the HCMV genome. While gpUL141 alone is sufficient to mediate retention of CD155 in the endoplasmic reticulum, UL141 requires assistance from additional HCMV-encoded functions to suppress expression of CD112

Identification of genetic variants associated with Huntington's disease progression: a genome-wide association study

Background Huntington's disease is caused by a CAG repeat expansion in the huntingtin gene, HTT. Age at onset has been used as a quantitative phenotype in genetic analysis looking for Huntington's disease modifiers, but is hard to define and not always available. Therefore, we aimed to generate a novel measure of disease progression and to identify genetic markers associated with this progression measure. Methods We generated a progression score on the basis of principal component analysis of prospectively acquired longitudinal changes in motor, cognitive, and imaging measures in the 218 indivduals in the TRACK-HD cohort of Huntington's disease gene mutation carriers (data collected 2008–11). We generated a parallel progression score using data from 1773 previously genotyped participants from the European Huntington's Disease Network REGISTRY study of Huntington's disease mutation carriers (data collected 2003–13). We did a genome-wide association analyses in terms of progression for 216 TRACK-HD participants and 1773 REGISTRY participants, then a meta-analysis of these results was undertaken. Findings Longitudinal motor, cognitive, and imaging scores were correlated with each other in TRACK-HD participants, justifying use of a single, cross-domain measure of disease progression in both studies. The TRACK-HD and REGISTRY progression measures were correlated with each other (r=0·674), and with age at onset (TRACK-HD, r=0·315; REGISTRY, r=0·234). The meta-analysis of progression in TRACK-HD and REGISTRY gave a genome-wide significant signal (p=1·12 × 10−10) on chromosome 5 spanning three genes: MSH3, DHFR, and MTRNR2L2. The genes in this locus were associated with progression in TRACK-HD (MSH3 p=2·94 × 10−8 DHFR p=8·37 × 10−7 MTRNR2L2 p=2·15 × 10−9) and to a lesser extent in REGISTRY (MSH3 p=9·36 × 10−4 DHFR p=8·45 × 10−4 MTRNR2L2 p=1·20 × 10−3). The lead single nucleotide polymorphism (SNP) in TRACK-HD (rs557874766) was genome-wide significant in the meta-analysis (p=1·58 × 10−8), and encodes an aminoacid change (Pro67Ala) in MSH3. In TRACK-HD, each copy of the minor allele at this SNP was associated with a 0·4 units per year (95% CI 0·16–0·66) reduction in the rate of change of the Unified Huntington's Disease Rating Scale (UHDRS) Total Motor Score, and a reduction of 0·12 units per year (95% CI 0·06–0·18) in the rate of change of UHDRS Total Functional Capacity score. These associations remained significant after adjusting for age of onset. Interpretation The multidomain progression measure in TRACK-HD was associated with a functional variant that was genome-wide significant in our meta-analysis. The association in only 216 participants implies that the progression measure is a sensitive reflection of disease burden, that the effect size at this locus is large, or both. Knockout of Msh3 reduces somatic expansion in Huntington's disease mouse models, suggesting this mechanism as an area for future therapeutic investigation

Affinity-labelling of the thyrotropin receptor. Characterization of the photoactive ligand

Thyrotropin (TSH) has been coupled to the photoactive heterobifunctional reagent N-hydroxysuccinimidyl 4-azidobenzoate (HSAB) and the properties of the product (HSAB-TSH) investigated. Preparations of HSAB-TSH containing two molecules of HSAB per molecule of TSH were used in most experiments and these preparations retained about 40% of the original receptor-binding activity of the TSH. HSAB-TSH could be labelled with 125I and cross-linked to porcine and human TSH receptors. Analysis of the cross-linked complexes indicated that the receptors consisted of two subunits (designated A and B) linked by a disulphide bridge. In the case of the human TSH receptor, the A- and B-subunits had approximate Mr values of 50 000 and 30 000 respectively, whereas the Mr values for porcine TSH-receptor A- and B-subunits were approx. 45 000 and 25 000 respectively. Only the A subunit was cross-linked to TSH. Comparison of the effects of trypsin and mercaptoethanol on the TSH-TSH-receptor complexes suggested that the trypsin cleavage point on the A-subunit was at a point close to the disulphide bridge

A structure for the porcine TSH receptor

Affinity purified, detergent-solubilised porcine TSH receptors have been crosslinked to a 125I-labelled photoactive derivative of TSH and analysed by gel electrophoresis, gel filtration and sucrose density gradient centrifugation. Our studies suggest that the porcine TSH receptor is made up of a hydrophilic A subunit with an Mr about 45000 linked to an amphiphilic B subunit (Mrapprox. 25 000) by a disulphide bridge(s). The A subunit forms the binding site for TSH on the outside of the cell membrane. The B subunit appears to penetrate the membrane and form the site for interaction with adenylate cyclase either in the lipid bilayer or close to the cytoplasmic surface of the membrane