The clinical manifestations of AIDS (acquired immune deficiency syndrome) often include neuropsychiatric and neurological deficits, including early memory loss and progressive dementia. HIV (human immunodeficiency virus), the aetiological agent of AIDS, is probably carried by infected macrophages in the central nervous system. The virus enters cells by binding its envelope glycoprotein gp120 to the CD4 antigen present on brain and immune cells. From the data reported in this paper, we now suggest that the neuronal deficits associated with HIV may not be entirely a result of infectivity, but that gp120 shed from HIV could directly produce the neuropathology as a result of its interference with endogenous neurotrophic substances. It is known that an analogue of a sequence contained in vasoactive intestinal peptide (VIP) occurs in all known sequenced gp120 isolates and that VIP is important for neuronal survival in cell culture. Here we show that purified gp120 from two diverse HIV isolates and a recombinant gp120 from a third isolate were all potent in specifically producing significant neuronal cell death in dissociated hippocampal cultures derived from fetal mice, and that this could be reduced by monoclonal antibodies against the murine CD4 antigen and completely antagonized by VIP.

Interferons (IFNs) induce transcription of major histocompatibility complex (MHC) class I genes through the conserved IFN consensus sequence (ICS) that contains an IFN response motif shared by many IFN-regulated genes. By screening mouse AZAP expression libraries with the ICS as a probe, we isolated a cDNA clone encoding a protein that binds the ICS, designated ICSBP. Protein blot analysis with labeled oligonucleotide probes showed that ICSBP binds not only the MHC class I ICS but also IFN response motifs of many IFN-regulated genes, as well as a virus-inducible element of the IFN-,f gene. The ICSBP cDNA encodes 424 amino acids and a long 3' untranslated sequence. The N-terminal 115 amino acids correspond to a putative DNA-binding domain and show significant sequence similarity with other cloned IFN response factors (IRF-1 and IRF-2). Because of the structural similarity and shared binding specificity, we conclude that ICSBP is a third member of the IRF gene family, presumably playing a role in IFN-and virus-mediated regulation of many genes. Although IRF-1 and IRF-2 share some similarity in their C-terminal regions, ICSBP shows no similarity to IRF-1 or IRF-2 in this region, suggesting that it is more distantly related. We show that ICSBP mRNA is expressed predominantly in lymphoid tissues and is inducible preferentially by IFN-y. The induction by IFN-y appears to be predominant in lymphocytes and macrophages, implying that ICSBP plays a regulatory role in cells of the immune system. The presence of multiple factors that bind common IfN response motifs may partly account for the complexity and diversity of IFN action as well as IFNregulated gene expression.Interferons (IFNs) are potent biomodulators (1, 2). They regulate many cellular genes involved in defense against viral and bacterial infection, enhance immune responses, and control cell growth. We have been interested in IFNmediated induction of major histocompatibility complex (MHC) class I genes. We and others have observed that a highly conserved upstream cis element, the interferon consensus sequence (ICS), is responsible for IFN-mediated induction of MHC class I genes (3-6). Several nuclear factors that bind to the ICS are either constitutively expressed or induced by IFN treatment (3, 7). A number of groups (8)(9)(10)(11)(12)(13)(14)(15)(16)(17) have shown that other IFN-regulated genes have IFN response motifs that are very similar to part of the ICS and to each other. These elements are essential for virus-or IFNinduced transcription of the corresponding genes and bind to the same or very similar factors. These reports put forward the notion that IFN genes and IFN-regulated genes are controlled by shared cis motifs that bind shared transcription factors. We

The long terminal repeat of Moloney murine leukemia virus (MuLV) contains the upstream conserved region (UCR). The UCR core sequence, CGCCATTTT, binds a ubiquitous nuclear factor and mediates negative regulation of MuLV promoter activity. We have isolated murine cDNA clones encoding a protein, referred to as UCRBP, that binds specifically to the UCR core sequence. Gel mobility shift assays demonstrate that the UCRBP fusion protein expressed in bacteria binds the UCR core with specificity identical to that of the UCR-binding factor in the nucleus of murine and human cells. Analysis of full-length UCRBP cDNA reveals that it has a putative zinc finger domain composed of four C2H2 zinc fingers of the GLI subgroup and an N-terminal region containing alternating charges, including a stretch of 12 histidine residues. The 2.4-kb UCRBP message is expressed in all cell lines examined (teratocarcinoma, B-and T-cell, macrophage, fibroblast, and myocyte), consistent with the ubiquitous expression of the UCR-binding factor. Expression of type C retroviruses, including the murine leukemia viruses (MuLV), is regulated by various sequence motifs in the long terminal repeat (LTR), which are conserved in both the replication-defective endogenous and the exogenous/infectious viruses (14, 46, 47, 53). The 3' end of the LTR contains the promoter elements, the CCAAT and the TATA motifs. The middle part of the LTR contains at least six known cis motifs, and these function as a strong enhancer (27,46). This middle region may also be involved in negative regulation of viral transcription in undifferentiated embryonal carcinoma (EC) cells (17). The 5' part of the LTR of both the infectious and the MuLV-related endogenous defective retroviruses contains the upstream conserved region (UCR), whose core motif is CGCCATTTT (the location of which is shown in Fig. 1). The UCR and the other downstream motifs are conserved in over 90% of more than 35 mammalian type C retrovirus isolates (13,15,24).We have previously shown that the UCR binds a ubiquitous nuclear factor(s) and that in murine L cells, the UCR and its binding factor(s) are involved in negative regulation of MuLV promoter activity (13). In addition to our work, the UCR-binding activity also has been reported in a study of developmental regulation of MuLV in undifferentiated F9 EC cells (51). These authors found that the UCR-binding activity occurs irrespective of retinoic acid-induced differentiation of F9 cells and that developmental control of MuLV is mediated by an element independent of the UCR.With the aim of further studying the structure and function of the UCR-binding factor, we have cloned a gene encoding a UCR-binding protein (UCRBP) by screening several * Corresponding author. expression libraries with multimerized UCR. Here we report the isolation and initial characterization of a full-length UCRBP cDNA that encodes a C2H2 zinc finger protein and is capable of specifically binding to the UCR core motif. We show that transient transfection of an expressible UCRBP cDNA leads ...

Purpose:The purpose of this study was to examine the tumor specificity, cytotoxicity, and granulocyte macrophage colony-stimulating factor expression of CG0070, a conditionally replicating oncolytic adenovirus, in human bladder transitional cell carcinoma (TCC) cell lines and determine its antitumor efficacy in bladderTCC tumor models. Experimental Design: Virus yield and cytotoxicity assays were used to determine tumor specificity and virus replication-mediated cytotoxicity of CG0070 in a panel of human bladderTCC cell lines and primary cells in vitro. Two s.c. and one orthotopic bladderTCC xenograft tumor models were used to assess antitumor activity of CG0070. Results: In a matched isogenic pair of cell lines with differing retinoblastoma (Rb) pathway status, CG0070 showed selective E1a and granulocyte macrophage colony-stimulating factor (GM-CSF) expression in Rb pathway^defective cells. CG0070 replicated in Rb-defective bladderTCC cell lines as efficiently as wild-type adenovirus but produced 100-fold less virus in normal human cells. CG0070 was up to 1,000-fold more cytotoxic in Rb pathway^defective bladder TCC cells in comparison with normal human cells. Antitumor activity of CG0070 was shown in two bladder TCC s.c. xenograft tumor models following intratumoral injections and intravesical treatment in an orthotopic xenograft tumor model when compared with PBS treatment. Conclusions: In vitro and in vivo studies showed the selective replication, cytotoxicity, GM-CSF production, and antitumor efficacy of CG0070 in several bladder TCC models, suggesting a potential utility of this oncolytic agent for the treatment of bladder cancer. Further studies are warranted to show the role of human GM-CSF in the antitumor efficacy of CG0070.