Given the unprecedented scale of the recent Ebola and Zika viral epidemics, it is crucial to understand the biology of host factors with broad antiviral action in order to develop novel therapeutic approaches. Here, we look into one such factor: zinc finger antiviral protein (ZAP) inhibits a variety of RNA and DNA viruses. Alternative splicing results in two isoforms that differ at their C termini: ZAPL (long) encodes a poly(ADP-ribose) polymerase (PARP)-like domain that is missing in ZAPS (short). Previously, it has been shown that ZAPL is more antiviral than ZAPS, while the latter is more induced by interferon (IFN). In this study, we discovered and confirmed the expression of two additional splice variants of human ZAP: ZAPXL (extralong) and ZAPM (medium). We also found two haplotypes of human ZAP. Since ZAPL and ZAPS have differential activities, we hypothesize that all four ZAP isoforms have evolved to mediate distinct antiviral and/or cellular functions. By taking a geneknockout-and-reconstitution approach, we have characterized the antiviral, translational inhibition, and IFN activation activities of individual ZAP isoforms. Our work demonstrates that ZAPL and ZAPXL are more active against alphaviruses and hepatitis B virus (HBV) than ZAPS and ZAPM and elucidates the effects of splice variants on the action of a broad-spectrum antiviral factor. IMPORTANCE ZAP is an IFN-induced host factor that can inhibit a wide range of viruses, and there is great interest in fully characterizing its antiviral mechanism. This is the first study that defines the antiviral capacities of individual ZAP isoforms in the absence of endogenous ZAP expression and, hence, cross talk with other isoforms. Our data demonstrate that ZAP is expressed as four different forms: ZAPS, ZAPM, ZAPL, and ZAPXL. The longer ZAP isoforms better inhibit alphaviruses and HBV, while all isoforms equally inhibit Ebola virus transcription and replication. In addition, there is no difference in the abilities of ZAP isoforms to enhance the induction of type I IFN expression. Our results show that the full spectrum of ZAP activities can change depending on the virus target and the relative levels of basal expression and induction by IFN or infection.

The discovery of sodium taurocholate cotransporting polypeptide (NTCP) as the hepatitis B virus (HBV) receptor enabled researchers to create hepatoma cell lines susceptible to HBV infection. Infection in current systems, however, is inefficient and virus fails to spread. Infection efficiency is enhanced by treating cells with polyethylene glycol 8000 (PEG) during infection. However, this alone does not promote virus spread. Here we show that maintaining PEG in culture medium increases the rate of infection by at least one order of magnitude, and, most importantly, promotes virus spread. To demonstrate the utility of this system, we show that two interferon-stimulated genes (ISGs), ISG20 and tetherin, restrict HBV spread in NTCP-expressing hepatoma cells. Thus, this protocol can be easily applied to existing cell culture systems to study the complete HBV life cycle, including virus spread.

It has been well documented that a significant proportion of chronic anovulatory patients have elevated levels of dehydroepiandrosterone sulfate (DHEAS) and luteinizing hormone (LH) and normal levels of adrenocortiocotropic hormone (ACTH). We tested the hypothesis that the zones of human adrenal cortex that secrete DHEAS may contain LH/human chorionic gonadotropin (hCG) receptors. In situ hybridization showed the presence of hybridization signals representing LH/hCG receptor mRNA transcripts in the zona reticularis. Immunocytochemistry demonstrated that the zona reticularis also contained LH/hCG receptor protein. The receptor transcripts and receptor protein are also present in the deeper layer of the zona fasciculata which can also secrete DHEAS. Double immunostaining revealed that LH/hCG receptors are present in the same cells that contain cytochrome P450 side chain cleavage enzyme, suggesting that the receptor containing cells are steroidogenic. These findings may potentially explain higher DHEAS levels in chronic anovulatory women who have normal ACTH and elevated LH levels.

Mast cells play critical roles in allergic responses, and calcium signaling controls the function of these cells, and a role for actin in regulating calcium influx into cells has been suggested. We have previously identified the actin reorganizing protein Drebrin as a target of the immunosuppressant BTP, which inhibits calcium influx into cells. We show here that Drebrin−/− mice exhibit reduced IgE-mediated histamine release and passive systemic anaphylaxis and Drebrin−/− mast cells also exhibit defects in FcεRI-mediated degranulation. Drebrin−/− mast cells exhibit defects in actin cytoskeleton organization and calcium responses downstream of the FcεRI, and agents that relieve actin reorganization rescue mast cell FcεRI induced degranulation. Our results indicate that Drebrin regulates the actin cytoskeleton and calcium responses in mast cells, thus regulating mast cell function in vivo.

Normal human skin contains a major 4.5 kb and several minor mRNA transcripts and a 66 kDa protein of luteinizing hormone (LH)/chorionic gonadotropin (hCG) receptors which are capable of binding exogenous 125I-hCG. The distribution of receptor transcripts and receptor protein are the highest in epidermis followed by hair follicles, sebaceous and sweat glands. LH/hCG receptors are co-localized with androgen receptors in all the skin appendages. These data are the first demonstration of skin containing LH/hCG receptors and would suggest that LH and hCG may regulate skin functions.