The human papillomavirus (HPV)‐16 oncogenes, E6 and E7, are transcribed preferentially in keratinocytes and cervical carcinoma cells due to a 5′ enhancer. An abundant peptide binding to a 37 nt enhancer element was purified from human keratinocytes by sequence‐specific DNA chromatography. This protein was identified as transcriptional enhancer factor (TEF)‐1 by complex mobility, binding to wild‐type and mutant SV40 and HPV‐16 enhansons and antigenic reactivity with two anti‐TEF‐1 antibodies. TEF‐1 is cell‐specific, but its transactivation also depends on a limiting, cell‐specific TEF‐1 ‘co‐activator’. We show that both TEF‐1 and the TEF‐1 co‐activator are active in human keratinocytes and essential for HPV‐16 transcription. TEF‐1 binding in vivo was necessary for HPV‐16 P97 promoter activity. Excess TEF‐1 and chimeric GAL4‐TEF‐1 specifically inhibited the P97 promoter by ‘squelching’, indicating that HPV‐16 transcription also requires a limiting TEF‐1 co‐activator. TEF‐1 and the TEF‐1 co‐activator functions mirrored HPV‐16 transcription by their presence in keratinocytes and cervical carcinoma cells and their absence from lymphoid B‐cells, but also functioned in liver cells where the HPV‐16 promoter is inactive. TEF‐1 and its associated co‐activator are thus part of a complex mechanism which determines the restricted cell range of the HPV‐16 E6 and E7 oncogene promoter.

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A total of 532 women with established cervical HPV infection have been prospectively followed (without treatment) since 1981 for a mean of 45 (SD 21) months. The patients were examined by colposcopy, PAP smears and/or punch biopsy every 6 months. The life-table method was applied to analyze the clinical course (i.e. regression and progression) of the HPV lesions, stratified by their colposcopic pattern, PAP smear findings and grade of CIN. During the follow-up, 107 (41.8%) of 256 patients with HPV-NCIN lesion in the first punch biopsy, experienced spontaneous regression. The corresponding proportions for HPV-CIN I, HPV-CIN II and HPV-CIN III lesions were 31.1%, 34.2%, and 20.7%, respectively. In the overall comparison between these four groups, the heterogeneity in the probability of regression was statistically significant (p = 0.0005). Clinical progression was also associated significantly with the histological grade of the lesions in the first biopsy. Progression rate was only 5.8% for HPV-NCIN lesions, as compared to 12.3% for HPV-CIN I, 20% for HPV-CIN II, and 55.2% for HPV-CIN III. The probability of progression varied significantly between the four groups (p less than 0.00001). Cumulative proportion of regression was 46% for patients with PAP smear class I, 84% with class II, and 82% for those with class III, cells, i.e. PAP smear was not of value in predicting the regression. However, PAP smears predicted clinical progression (p = 0.006 overall).(ABSTRACT TRUNCATED AT 250 WORDS)

DNA polymerase (pol) ⑀ is thought to be the leading strand replicase in eukaryotes, whereas pols and ␤ are believed to be mainly involved in re-synthesis steps of DNA repair. DNA elongation by the human pol ⑀ is halted by an abasic site (apurinic/ apyrimidinic (AP) site). In this study, we present in vitro evidence that human pols , ␤, and can perform translesion synthesis (TLS) of an AP site in the presence of pol ⑀, likely by initiating the 3OHs created at the lesion by the arrested pol ⑀. However, in the case of pols and ␤, this TLS requires the presence of a DNA gap downstream from the product synthesized by the pol ⑀, and the optimal gap for efficient TLS is different for the two polymerases. The presence of gaps did not affect the TLS capacity of human pol . Characterization of the reaction products showed that pol ␤ inserted dAMP opposite the AP site, whereas gap filling synthesis by pol resulted in single or double deletions opposite the lesion. The synthesis up to the AP site by pol ⑀ and the subsequent TLS by pols and ␤ are not influenced by human processivity factor proliferating cell nuclear antigen and human single-stranded DNA-binding protein replication protein A. The bypass capacity of pol at the AP site is greatly reduced when a truncated form of the enzyme, which has lost the BRCA1 C-terminal and proline-rich domains, is used. Collectively, our in vitro results support the existence of a mechanism of gap-directed TLS at an AP site involving a switch between the replicative pol ⑀ and the repair pols and ␤.Chromosomal DNA replication in eukaryotic cells requires three DNA polymerases (pols) 3 : pol ␣, pol ␦, and pol ⑀. pol ␣ is the only polymerase that has an associated activity for synthesis of RNA primers and is able to extend from such primers by synthesizing short stretches of DNA (1, 2). Subsequently, processive DNA synthesis is resumed by pol ␦ and/or pol ⑀. Recent work in yeast supports a model wherein, during normal DNA replication, pol ⑀ is primarily responsible for copying the leading strand, and pol ␦ is primarily responsible for copying the lagging strand (3).Abasic sites (AP sites) arise frequently by spontaneous hydrolysis of purines in DNA, represent a common intermediate of numerous DNA repair systems, and are among the most common endogenous DNA lesions generated during normal cell growth (4, 5).An AP site poses a serious problem to the advancement of a pol because the modified base has lost its coding capacity. Accordingly, its replication requires the intervention of one or more Y family polymerases in a process called translesion synthesis or TLS (for reviews see Refs. 6, 7). Recent publications have shown that among these polymerases human pol was able to insert nucleotides opposite the AP site and extend primers further past the lesion in vitro (8). Moreover, pol showed higher abasic lesion bypass capacity in vivo than pols , , and Rev1 (9). Furthermore, it has also been reported that an AP site could be bypassed in vitro by polymerases of other families such as pol ␣ (10), ...