PubMed · 14927103
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M ROTHMAN, A D MAYNARD, R CARTER. 1952. Traumatic hemothorax.. https://pubmed.ncbi.nlm.nih.gov/14927103/
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The human polyomavirus JC virus (JCV) is responsible for the CNS demyelination observed in cases of progressive multifocal leukoencephalopathy. The JCV regulatory region (promoter) is a hypervariable, noncoding, nucleotide sequence positioned between the early and late protein-coding regions in the viral genome. Selective binding of cellular transcription factors to this promoter region participates in the control of viral tropism. Hence, further study of these proteins might provide new insights into JCV tropism and associated pathogenesis. This review gives an overview of viral proteomics - the study of all proteins expressed from the viral gene transcripts, and all the cellular proteins that play a role in JCV tropism. It also describes a new biochemical approach for studying relevant JCV promoter-binding proteins, which is an anchored-JCV transcriptional promoter (ATP) assay. An ATP assay utilizes the product of PCR-amplified JCV promoter sequences coupled with Sepharose beads in order to capture and isolate cellular nuclear proteins with specific promoter-binding affinity for analysis. Proteins that bind to JCV-ATPs can be eluted and subjected to proteomic analysis. Insights from this approach may improve the understanding of viral and cellular parameters that control JCV tropism.
Antisense phosphodiester oligonucleotides (ONs), complexed to carriers such as cationic liposomes, inhibit the production of proteins. The biochemical and biophysical phenomena that govern the extent of this inhibition are still not fully understood. Major biological barriers limiting a pronounced antisense effect are the cellular entry and endosomal escape of the ONs containing liposomes, the release of the ONs from the liposomes and the extra- and intracellular degradation of the ONs. In this paper we focus on the latter barrier and evaluate, by fluorescence correlation spectroscopy (FCS), to what extent phosphodiester ONs complexed to DOTAP/DOPE liposomes, are protected against degradation by nucleases. Liposomes studied were either with or without a polyethyleneglycol (PEG) moiety at the surface. Using non-pegylated liposomes the phosphodiester ONs were initially adequately protected when exposed to DNase I. Indeed, in the mechanism for lipoplex formation as suggested by others, the ONs become trapped between lipid bilayers and are therefore shielded from the environment. However, after a few hours the phosphodiester ONs no longer stayed intact. This was explained by a gradual fusion of the lipoplexes in time thereby spontaneously releasing phosphodiester ONs. Using pegylated liposomes, a substantial fraction of the phosphodiester ONs degraded immediately after exposing the complexes to DNase I. Based on experimental evidence we suggest that the presence of the PEG-chains influences lipoplex formation so that the ONs are not trapped between lipid bilayers and therefore remain accessible by the DNase I enzyme.