Recombinant transmembrane CD59 (CD59-TM) confers complement resistance to GPI-anchored protein defective melanoma cells

Modulation of host CD59 expression by varicella-zoster virus in human xenografts in vivo

Varicella-zoster virus (VZV) is the causative agent of both chickenpox (varicella) and shingles (zoster). VZV survives host defenses, even with an intact immune system, and disseminates in the host before causing disease. To date, several diverse immunomodulatory strategies used by VZV to undermine host immunity have been identified; however, few studies have addressed the complement evasion strategies used by this virus. Here, we show that expression of CD59, which is a key member of host regulators of complement activation (RCA), is significantly upregulated in response to VZV infection in human T cells and dorsal root ganglia (DRG) but not in human skin xenografts in SCID-hu mice in vivo. This is the first report demonstrating that VZV infection upregulates host CD59 expression in a tissue-specific manner in vivo, which may aid VZV in complement evasion and pathogenesis.

GPI-anchored receptor clusters transiently recruit Lyn and G alpha for temporary cluster immobilization and Lyn activation: single-molecule tracking study 1

The signaling mechanisms for glycosylphosphatidylinositol-anchored receptors (GPI-ARs) have been investigated by tracking single molecules in living cells. Upon the engagement or colloidal gold–induced cross-linking of CD59 (and other GPI-ARs) at physiological levels, CD59 clusters containing three to nine CD59 molecules were formed, and single molecules of Gαi2 or Lyn (GFP conjugates) exhibited the frequent but transient (133 and 200 ms, respectively) recruitment to CD59 clusters, via both protein–protein and lipid–lipid (raft) interactions. Each CD59 cluster undergoes alternating periods of actin-dependent temporary immobilization (0.57-s lifetime; stimulation-induced temporary arrest of lateral diffusion [STALL], inducing IP₃ production) and slow diffusion (1.2 s). STALL of a CD59 cluster was induced right after the recruitment of Gαi2. Because both Gαi2 and Lyn are required for the STALL, and because Lyn is constitutively recruited to CD59 clusters, the STALL of CD59 clusters is likely induced by the Gαi2 binding to, and its subsequent activation of, Lyn within the same CD59 cluster.

Dynamic recruitment of phospholipase C gamma at transiently immobilized GPI-anchored receptor clusters induces IP3-Ca2+ signaling: single-molecule tracking study 2

Clusters of CD59, a glycosylphosphatidylinositol-anchored receptor (GPI-AR), with physiological sizes of approximately six CD59 molecules, recruit Gαi2 and Lyn via protein–protein and raft interactions. Lyn is activated probably by the Gαi2 binding in the same CD59 cluster, inducing the CD59 cluster's binding to F-actin, resulting in its immobilization, termed stimulation-induced temporary arrest of lateral diffusion (STALL; with a 0.57-s lifetime, occurring approximately every 2 s). Simultaneous single-molecule tracking of GFP-PLCγ2 and CD59 clusters revealed that PLCγ2 molecules are transiently (median = 0.25 s) recruited from the cytoplasm exclusively at the CD59 clusters undergoing STALL, producing the IP₃–Ca²⁺ signal. Therefore, we propose that the CD59 cluster in STALL may be a key, albeit transient, platform for transducing the extracellular GPI-AR signal to the intracellular IP₃–Ca²⁺ signal, via PLCγ2 recruitment. The prolonged, analogue, bulk IP₃–Ca²⁺ signal, which lasts for more than several minutes, is likely generated by the sum of the short-lived, digital-like IP₃ bursts, each created by the transient recruitment of PLCγ2 molecules to STALLed CD59.

Determination of CD59 protein in normal human serum by enzyme immunoassay, using octyl-glucoside detergent to release glycosyl-phosphatidylinositol-CD59 from lipid complex

In this study we have optimised the enzyme immunoassay (ELISA) to quantify CD59 antigen in human serum or plasma. The glycosyl-phosphatidylinositol (GPI)-linked form of CD59 is known to complex with serum high-density lipoprotein. For ELISA optimisation, therefore, we investigated the effect of detergents, added to the sample diluent, on the determined values of CD59. Values obtained in the presence of octyl-glucoside (OG) for 20 adults aged 18-35 years and 17 children 1-5 years old were, respectively, 33-119 ng/ml (mean +/- S.D.: 66+/-22 ng/ml) and 37-143 ng/ml (76+/-33 ng/ml). These results were higher than those measured without OG and were in contrast with published results showing absence, or eight to nine times lower levels, of the protein in serum. A known range for serum concentrations of CD59 in healthy individuals will establish an important reference point for clinical work and for the investigation of diseases involving the complement membrane attack complex (MAC) and its regulation.