Transforming growth factor-β1 plays a key role in the pathogenesis of pulmonary fibrosis, mediating extracellular matrix (ECM) gene expression through a series of intracellular signaling molecules, including Smad2 and Smad3. We show that Smad3 null mice (knockout (KO)) develop progressive age-related increases in the size of alveolar spaces, associated with high spontaneous presence of matrix metalloproteinases (MMP-9 and MMP-12) in the lung. Moreover, transient overexpression of active TGF-β1 in lungs, using adenoviral vector-mediated gene transfer, resulted in progressive pulmonary fibrosis in wild-type mice, whereas no fibrosis was seen in the lungs of Smad3 KO mice up to 28 days. Significantly higher levels of matrix components (procollagen 3A1, connective tissue growth factor) and antiproteinases (plasminogen activator inhibitor-1, tissue inhibitor of metalloproteinase-1) were detected in wild-type lungs 4 days after TGF-β1 administration, while no such changes were seen in KO lungs. These data suggest a pivotal role of the Smad3 pathway in ECM metabolism. Basal activity of the pathway is required to maintain alveolar integrity and ECM homeostasis, but excessive signaling through the pathway results in fibrosis characterized by inhibited degradation and enhanced ECM deposition. The Smad3 pathway is involved in pathogenic mechanisms mediating tissue destruction (lack of repair) and fibrogenesis (excessive repair).

During infection with herpes simplex virus type 1 (HSV-1), VP16 serves multiple functions, including transcriptional activation of viral immediate early genes and downregulation of the virion host shutoff protein vhs. Furthermore, VP16 has been shown to be involved in some aspect of virus assembly and/or maturation. Experiments with a VP16 null virus, 8MA, suggested that VP16 plays a direct role in virion assembly, since removal of VP16 from the HSV-1 genome results in reduced levels of encapsidated DNA and a failure to produce extracellular enveloped particles. However, VP16 null mutants display a severe translational arrest due to unrestrained vhs activity, thus complicating interpretation of these data. We examine here the role of VP16 in virion assembly and egress in the context of a vhs null background, using the virus 8MA/⌬Sma (VP16 ؊ vhs ؊ ). Comparison of 8MA and 8MA/⌬Sma with respect to viral DNA accumulation and encapsidation and accumulation of the major capsid protein, VP5, revealed that the 8MA lethal phenotype is only partially due to uncontrolled vhs activity, indicating that VP16 is required in HSV-1 virion formation. Electron microscopy confirmed these results and further showed that VP16 is required for HSV-1 egress beyond the perinuclear space. In addition, we describe the isolation and characterization of an 8MA derivative capable of propagation on Vero cells, due to second site mutations in the vhs and UL53 (gK) genes. Taken together, these results show that VP16 is required for viral egress downstream of the initial envelopment step and further underscore the importance of VP16 in controlling vhs activity within an infected cell.Herpes simplex virus type 1 (HSV-1) is a large DNA virus consisting of an icosahedral capsid surrounded by an amorphous protein layer termed the tegument and bounded by an envelope derived from host membranes (50). The tegument contains important regulatory proteins that are released into the newly infected cell following fusion of the virion envelope with the host cell plasma membrane. While the functions of many of the tegument proteins have yet to be precisely defined, several have been shown to aid in the initiation of the viral replicative cycle (50). Among these are VP16 (also known as Vmw65, ICP25, UL48, or ␣-TIF) (5,11,44,46) and the virion host shutoff protein (vhs or UL41 gene product) (21,34,48,52).VP16 is an abundant 65-kDa virion phosphoprotein that is synthesized late in infection and subsequently packaged into virions (37-39). VP16 delivered by the infecting virion acts during the earliest stages of infection to stimulate transcription of the viral immediate-early (IE) genes, thereby facilitating the onset of the lytic program of viral gene expression (reviewed in references 41 and 50). Intensive studies have shown that the C-terminal portion of VP16 is a potent transcriptional activation domain and that VP16 is targeted to the TAATGA-RATTC consensus sequence found in IE promoters through interactions with the host factors Oct-1 and HCF. Mutations tha...

Herpes simplex virus (HSV) virions contain two regulatory proteins that facilitate the onset of the lytic cycle: VP16 activates transcription of the viral immediate‐early genes, and vhs triggers shutoff of host protein synthesis and accelerated turnover of cellular and viral mRNAs. VP16 and vhs form a complex in infected cells, raising the possibility of a regulatory link between them. Here we show that viral protein synthesis and mRNA levels undergo a severe decline at intermediate times after infection with a VP16 null mutant, culminating in virtually complete translational arrest. This phenotype was rescued by a transcriptionally incompetent derivative of VP16 that retains vhs binding activity, and was eliminated by inactivating the vhs gene. These results indicate that VP16 dampens vhs activity, allowing HSV mRNAs to persist in infected cells. Further evidence supporting this hypothesis came from the demonstration that a stably transfected cell line expressing VP16 was resistant to host shutoff induced by superinfecting HSV virions. Thus, in addition to its well known function as a transcriptional activator, VP16 stimulates viral gene expression at a post‐transcriptional level, by sparing viral mRNAs from degradation by one of the virus‐induced host shutoff mechanisms.

In a study of 197 cases of histologically confirmed invasive cervical cancer, 61% of biopsies were positive for human papillomavirus (HPV) DNA by Southern or dot-blot hybridization. An association between detection of HPV DNA and oral contraceptive use was observed when HPV-positive and -negative cases were compared. Women reporting recent or long-term (greater than 4 yrs) oral contraceptive use were at 2.3 and 2.9-fold increased risks of HPV positivity, respectively. An increased risk of HPV positivity was also associated with formal education and with urban residence, while long-term smoking was negatively associated with HPV detection. A non-significant trend of increasing risk of HPV positivity with increasing number of sexual partners of the women and of the male partners of monogamous women was observed. Detection of HPV DNA was not associated with other cervical cancer risk factors examined, including age at first coitus, number of pregnancies, and Pap smear screening history. Our findings suggest either an interaction between HPV infection and oral contraceptive use in the genesis of cervical cancer or an increased expression of HPV genome in neoplasms of oral contraceptive users. These observations also support a multifactorial model of cervical cancer causation.

Acquisition of the immortal phenotype by tumor cells represents an essential and potentially rate-limiting step in tumorigenesis. To identify changes in gene expression that are associated with the early stages of cell immortalization, we compared genetically matched pairs of pre-immortal and immortal human cell clones by mRNA di erential display. Two transcripts, denoted CIR1 and CIR2, were identi®ed which were up-regulated in immortal cells. Sequence analysis revealed CIR1 to be identical to the recently cloned CROC1/UEV-1 gene, whereas CIR2 corresponds to an as yet uncharacterized 1.2 kb mRNA. A 5 ± 6-fold elevation in CIR1/CROC1 expression and a 2 ± 3-fold elevation in CIR2 expression were observed in SV40-transformed human enbryonic kidney cells immediately following proliferative crisis, suggesting a potential role for these genes in immortalization. Expression of CIR1/CROC1 was found to be elevated also in a variety of immortal human tumorderived cell lines, as compared to their normal tissue counterparts. These results are compatible with induction of CIR1/CROC1 being an early event in the acquisition of immortality and with a role for this gene in the immortal phenotype of tumor cells.