No abstract

Human papillomaviruses (HPVs) are small circular DNA viruses that cause warts. Significantly, infection with high-risk anogenital HPVs, such as HPV type 16 (HPV16), is associated with human cancers, specifically cervical cancer (50). The life cycle of HPVs is intimately tied to the differentiation status of the host epithelium and has two distinct stages: the nonproductive stage and the productive stage. The nonproductive stage of the viral life cycle occurs in the basal compartment of the host epithelium where the virus gains entry, presumably at a site of wounding. In this nonproductive stage, the virus maintains itself as a low-copy-number nuclear plasmid (10). As the host cells differentiate, the productive stage of the viral life cycle occurs in the suprabasal compartment of the epithelium. In the productive stage, viral DNA is amplified; the capsid genes, L1 and L2, are expressed; and progeny virions are produced.The 7,904-bp HPV16 genome contains eight viral genes encoding six nonstructural and two structural proteins. Three of the nonstructural proteins, E5, E6, and E7, are designated as oncoproteins because they are able to transform cells in vitro (22,28,29,33,37,45) and, in the case of E6 and E7, induce tumors in vivo (23,42). Two of the other three nonstructural proteins, E1 and E2, are involved in DNA replication and transcription of the viral genome. E4 is predicted to contribute indirectly to the replication of the viral DNA genome in the productive stage (J. Doorbar, unpublished data; T. Nakahara, personal communication). L1 and L2 are the major and minor capsid proteins, respectively.Unlike E6 and E7, the major viral oncoproteins, the E5 protein of HPV16 is not commonly found in cervical carcinoma cells (3, 4). However, it is considered an oncogene given its ability to transform mouse fibroblasts and keratinocytes, cause the mitogenic stimulation of human keratinocytes, and cooperate with E7 to stimulate proliferation of human keratinocytes (5,28,29,37,45). The E5 gene of HPV16 is an 83-amino-acid hydrophobic membrane protein (8, 21) found localized to the Golgi apparatus, endoplasmic reticulum, and nuclear membrane (11).What led researchers to study the HPV16 E5 protein was that, in contrast to the HPVs, the major transforming protein of bovine papillomavirus type 1 (BPV1) is the E5 protein, a 44-amino-acid highly hydrophobic protein that is localized predominantly to the Golgi and exists as homodimers (13,40,41). The BPV1 E5 protein is able to transform both murine fibroblasts and keratinocytes in transformation assays in vitro (9,

β‐ and γ‐cytoplasmic actin are nearly indistinguishable in their amino acid sequence, but are encoded by different genes that play non‐redundant biological roles. The key determinants that drive their functional distinction are unknown. Here, we tested the hypothesis that β- and γ-actin functions are defined by their nucleotide, rather than their amino acid sequence, using targeted editing of the mouse genome. Although previous studies have shown that disruption of β-actin gene critically impacts cell migration and mouse embryogenesis, we demonstrate here that generation of a mouse lacking β-actin protein by editing β-actin gene to encode γ-actin protein, and vice versa, does not affect cell migration and/or organism survival. Our data suggest that the essential in vivo function of β-actin is provided by the gene sequence independent of the encoded protein isoform. We propose that this regulation constitutes a global ‘silent code’ mechanism that controls the functional diversity of protein isoforms.

The temperature-dependent variability of a Pb2+-specific 8-17E DNAzyme catalytic beacon sensor has been addressed through the introduction of mismatches in the DNAzyme, and the resulting sensors resist temperature-dependent variations from 4 to 30 °C.

Alpha synuclein (α-syn) is a central player in neurodegeneration, but the mechanisms triggering its pathology are not fully understood. Here we found that α-syn is a highly efficient substrate for arginyltransferase ATE1 and is arginylated in vivo by a novel mid-chain mechanism that targets the acidic side chains of E46 and E83. Lack of arginylation leads to increased α-syn aggregation and causes the formation of larger pathological aggregates in neurons, accompanied by impairments in its ability to be cleared via normal degradation pathways. In the mouse brain, lack of arginylation leads to an increase in α-syn’s insoluble fraction, accompanied by behavioral changes characteristic for neurodegenerative pathology. Our data show that lack of arginylation in the brain leads to neurodegeneration, and suggests that α-syn arginylation can be a previously unknown factor that facilitates normal α-syn folding and function in vivo.