A novel dendritic cell (DC)-

. This suggests that the mechanism of SARS-CoV assembly differs from that of other studied coronaviruses, which only require M and E proteins for VLP formation. When coexpressed, the native envelope trimeric S glycoprotein is incorporated onto VLPs. Interestingly, when a fluorescent protein tag is added to the C-terminal end of N or S protein, but not M protein, the chimeric viral proteins can be assembled within VLPs and allow visualization of VLP production and trafficking in living cells by state-of-the-art imaging technologies. Fluorescent VLPs will be used further to investigate the role of cellular machineries during SARS-CoV egress.Coronaviruses are positive-sense RNA enveloped viruses that belong to the Coronaviridae family in the Nidovirales order. These viruses are found in a wide variety of animals and can cause respiratory and enteric disorders of diverse severity (11,18). In the past 5 years, several human and animal coronaviruses have been discovered, including the highly pathogenic virus responsible for the severe acute respiratory syndrome (SARS-CoV) (34,58, 60,64,68,69). Coronavirus particles consist of a helical nucleocapsid structure, formed by the association between nucleocapsid (N) phosphoproteins and the viral genomic RNA, which is surrounded by a lipid bilayer where three or four types of structural proteins are inserted: the spike (S), the membrane (M), and the envelope (E) proteins and, for some coronaviruses only, the hemagglutinin-esterase (HE) protein (for a review, see reference 14). Once sufficient amounts of new genomic RNA and structural proteins have been produced, assembly of particles occurs. Assembly and release of virions are the last stages of the virus life cycle.The triple-spanning membrane glycoprotein M drives the assembly of coronavirus, which bud into the lumen of the endoplasmic reticulum-Golgi intermediary compartment (ERGIC) (32,33,62,63). M is the most abundant envelope protein that sorts viral components to be incorporated into virions. M oligomerization, mainly driven by its transmembrane domain, is believed to allow the formation of a lattice of M proteins at ERGIC membranes (16, 41). S and E membrane proteins are integrated into the lattice through lateral interactions with M, whereas N and viral RNA interact with M C-terminal domain, which is exposed to the cytosol (4,8,15,19,30,36,48,54,55). The coronavirus S protein, responsible for receptor binding and membrane fusion, does not seem to have any major role in coronavirus assembly. Recent studies show that E is a viroporin that forms ion channels (46,66,67). Despite its minor incorporation into virion particles (7,22,40), the small E protein plays an important but not fully understood role in virus morphogenesis and budding (20,35,70). Studies performed on coronaviruses, including the SARS-CoV, demonstrate that depletion of the E gene from coronavirus genome strongly diminish virus growth and particle formation (9,12,35,37,57). The N protein self-associates and encapsidates the RNA genome for incorporation i...

Liver steatosis is associated with the development of insulin resistance and the pathogenesis of type 2 diabetes. We tested the hypothesis that protein signals originating from steatotic hepatocytes communicate with other cells to modulate metabolic phenotypes. We show that the secreted factors from steatotic hepatocytes induce pro-inflammatory signaling and insulin resistance in cultured cells. Next, we identified 168 hepatokines, of which 32 were differentially secreted in steatotic versus non-steatotic hepatocytes. Targeted analysis showed that fetuin B was increased in humans with liver steatosis and patients with type 2 diabetes. Fetuin B impaired insulin action in myotubes and hepatocytes and caused glucose intolerance in mice. Silencing of fetuin B in obese mice improved glucose tolerance. We conclude that the protein secretory profile of hepatocytes is altered with steatosis and is linked to inflammation and insulin resistance. Therefore, preventing steatosis may limit the development of dysregulated glucose metabolism in settings of overnutrition.

Future therapeutic applications of differentiated human embryonic stem cells (hESC) carry a risk of teratoma formation by contaminating undifferentiated hESC. We generated 10 monoclonal antibodies (mAbs) against surface antigens of undifferentiated hESC, showing strong reactivity against undifferentiated, but not differentiated hESC. The mAbs did not cross react with mouse fibroblasts and showed weak to no reactivity against human embryonal carcinoma cells. Notably, one antibody (mAb 84) is cytotoxic to undifferentiated hESC and NCCIT cells in a concentration-dependent, complementindependent manner. mAb 84 induced cell death of undifferentiated, but not differentiated hESC within 30 minutes of incubation, and immunoprecipitation of the mAb-antigen complex revealed that the antigen is podocalyxin-like protein-1. Importantly, we observed absence of tumor formation when hESC and NCCIT cells were treated with mAb 84 prior to transplantation into severe combined immunodeficiency mice. Our data indicate that mAb 84 may be useful in eliminating residual hESC from differentiated cells populations for clinical applications.