Human papillomavirus type 16 P670 promoter is negatively regulated by CCAAT displacement protein

Genetic Diversity and Possible Origins of the Hepatitis B Virus in Siberian Natives

A total of 381 hepatitis B virus (HBV) DNA sequences collected from nine groups of Siberian native populations were phylogenetically analyzed along with 179 HBV strains sampled in different urban populations of former western USSR republics and 50 strains from Central Asian republics and Mongolia. Different HBV subgenotypes predominated in various native Siberian populations. Subgenotype D1 was dominant in Altaian Kazakhs (100%), Tuvans (100%), and Teleuts (100%) of southern Siberia as well as in Dolgans and Nganasans (69%), who inhabit the polar Taimyr Peninsula. D2 was the most prevalent subgenotype in the combined group of Nenets, Komi, and Khants of the northern Yamalo-Nenets Autonomous Region (71%) and in Yakuts (36%) from northeastern Siberia. D3 was the main subgenotype in South Altaians (76%) and Buryats (40%) of southeastern Siberia, and in Chukchi (51%) of the Russian Far East. Subgenotype C2 was found in Taimyr (19%) and Chukchi (27%), while subgenotype A2 was common in Yakuts (33%). In contrast, D2 was dominant (56%) in urban populations of the former western USSR, and D1 (62%) in Central Asian republics and Mongolia. Statistical analysis demonstrated that the studied groups are epidemiologically isolated from each other and might have contracted HBV from different sources during the settlement of Siberia.

Regulation of the human papillomavirus type 16 late promoter by transcriptional elongation

Transcripts from the late promoter of human papillomavirus type 16 (HPV16) are upregulated upon host cell differentiation. Differentiation-dependent transcript regulation is thought to sequester viral antigens in the uppermost epithelial layers, facilitating immune evasion. The mechanisms regulating late promoter upregulation during differentiation are poorly characterized. We show that the late promoter is upregulated at the transcriptional level and that the viral enhancer stimulates promoter activity. Using kinase inhibition and chromatin immunoprecipitation analysis, we show evidence for differentiation-dependent enhancement of transcript elongation. Three factors that promote transcript elongation, cyclin dependent kinase 9 (CDK9), CDK8 (a subunit of the Mediator complex), and bromodomain containing protein 4 (Brd4) are recruited to viral genomes upon differentiation, and each plays a role in promoter activity. These results shed light on the transcriptional processes utilized by HPV16 for proper regulation of gene expression during the viral life cycle.

Molecular characterization of the region 7q22.1 in splenic marginal zone lymphomas

Splenic marginal zone lymphomas (SMZL) are an uncommon type of B-cell non-Hodgkin's lymphoma (NHL-B) in which no specific chromosomal translocations have been described. In contrast, the most frequent cytogenetic abnormality is the loss of the long arm of chromosome 7 (7q). Previous reports have located this loss in the 7q32 region. In order to better characterize the genomic imbalances in SMZL, molecular studies were carried out in 73 patients with SMZL. To gain insight into the mapping at 7q a tiling array was also used. The results confirmed the loss of 7q as the most frequent change. In addition, several abnormalities, including 4q22.1, 1q21.3–q22, 6q25.3, 20q13.33, 3q28, 2q23.3–q24.1 and 17p13, were also present. A loss of 7q22.1 at 99925039–101348479 bp was observed in half of the cases. The region of 7q22.1 has not previously been characterised in SMZL. Our results confirmed the presence of a new region of loss on chromosome 7 in these NHL.

Identification of nucleolin as a protein that binds to human papillomavirus type 16 DNA

Transcription, replication, and segregation of human papillomaviruses (HPVs) are regulated by various host factors, but our understanding of host proteins that bind to the HPV genome is limited. Here we report the results of a search of cellular proteins that can associate with specific genomic regions of HPV type 16 (HPV16). We found that human nucleolin, an abundant nucleolar protein, was preferentially captured in vitro by an HPV16 genomic fragment from nucleotide positions (nt) 531-780. Electrophoretic mobility shift assays with a bacterially expressed nucleolin revealed that nucleolin bound to an HPV16 genomic region between nt 604 and 614 in a sequence-dependent manner. Chromatin immunoprecipitation analysis showed that both exogenous and endogenous nucleolin bound to a plasmid containing the HPV16 genomic region in HeLa cells. Furthermore, nucleolin associated with the HPV16 genome stably maintained in HPV16-infected W12 cells, suggesting that the nucleolin binding may be involved in the dynamics of the HPV genome in cells.

[Life cycle of HPV governed by the differentiation program of epithelial cell]

Papillomavirus is a pathogenic virus that induces benign tumor at the infected lesion, and its association with malignant tumor was first identified by R. Shope using animal model. A variety of cancers have been reported to be associated with the infection of human papillomavirus since the report by H. zur Hausen that describes a connection between the HPV infection and cervical cancer. The HPV infection is broadly distributed as a sexually transmitted disease (STD) and recently the initial age diagnosed as the cervical cancer is getting lowered. Because of its clinical importance, the study on HPV has been focused on the oncogenic properties, and the results of which had great impacts on the researches of the tumor suppressors, such as p53 and pRb, and "ubiquiitn-proteasome" pathway. On the other hand, the biological properties of HPV remain mostly disclosed. The lifecycle of HPV is tightly linked to the differentiation program of the target epithelial cell, and this unique property has hampered the study on the HPV replication mechanism. Here we summarized the findings on the HPV lifecycle, including the virus gene functions, the regulation of viral gene expression and replication.

Repression of human cytomegalovirus major immediate early gene expression by the cellular transcription factor CCAAT displacement protein

Initiation of human cytomegalovirus (HCMV) productive infection is dependent on the major immediate early (MIE) genes ie1 and ie2. Several putative binding sites for CCAAT displacement protein (CDP or CUX1) were identified within the MIE promoter/regulatory region. Binding assays demonstrated binding of CUX1 to MIE-region oligonucleotides containing the CUX1 core binding sequence ATCGAT and mutagenesis of this sequence abrogated CUX1 binding. Furthermore, CUX1 repressed expression of a luciferase reporter construct controlled by the MIE promoter, and mutation of CUX1 binding sites within the promoter diminished this repressive function of CUX1. In the context of virus infection of HEK293 cells transfected with the CUX1 expression vector, CUX1 showed evidence of association with the HCMV MIE regulatory region and inhibited the capacity of the virus to express ie1 and ie2 transcripts, suggesting that this cellular factor regulates MIE gene expression following virus entry. These data identify a role for CUX1 in repressing HCMV gene expression essential for initiation of the replicative cycle.

Transcription factor human Skn-1a enhances replication of human papillomavirus DNA through the direct binding to two sites near the viral replication origin

Human papillomavirus type 16 (HPV16) DNA replication, which requires two viral proteins E1 and E2, occurs only in the differentiating epithelium. Besides the general factors necessary for cellular DNA synthesis, other unidentified cellular factors are assumed to be involved in the regulation of HPV DNA replication. In the present study, we found that the POU-domain transcription factor human Skn-1a, which induces the terminal differentiation of keratinocytes and activates the HPV16 late promoter, enhanced the transient replication of a plasmid containing the HPV16 replication origin in HEK293 cells when co-transfected with a plasmid expressing E1 and E2. An electrophoretic mobility shift assay with a bacterially expressed human Skn-1a or an extract of HeLa cells over-expressing human Skn-1a revealed the presence of two human Skn-1a binding sites that are distinct from the known three sites, near the replication origin. A chromatin immunoprecipitation analysis showed that human Skn-1a bound to these sites in cells. Nucleotide substitutions in the sites abolished the binding of human Skn-1a and the human Skn-1a-mediated replication enhancement. The data strongly suggest that, through the binding to the two sites, human Skn-1a enhances HPV DNA replication.