Bag3-Induced Autophagy Is Associated with Degradation of JCV Oncoprotein, T-Ag

JC virus, JCV, is a human neurotropic polyomavirus whose replication in glial cells causes the fatal demyelinating disease progressive multifocal leukoencephalopathy (PML). In addition, JCV possesses oncogenic activity and expression of its transforming protein, large T-antigen (T-Ag), in several experimental animals induces tumors of neural origin. Further, the presence of JCV DNA and T-Ag have been repeatedly observed in several human malignant tissues including primitive neuroectodermal tumors and glioblastomas. Earlier studies have demonstrated that Bag3, a member of the Bcl-2-associated athanogene (Bag) family of proteins, which is implicated in autophagy and apoptosis, is downregulated upon JCV infection of glial cells and that JCV T-Ag is responsible for suppressing the activity of the BAG3 promoter. Here, we investigated the possible impact of Bag3 on T-Ag expression in JCV-infected human primary glial cells as well as in cells derived from T-Ag-induced medulloblastoma in transgenic animals. Results from these studies revealed that overexpression of Bag3 drastically decreases the level of T-Ag expression by inducing the autophagic degradation of the viral protein. Interestingly, this event leads to the inhibition of JCV infection of glial cells, suggesting that the reduced levels of T-antigen seen upon the overexpression of Bag3 has a biological impact on the viral lytic cycle. Results from protein-protein interaction studies showed that T-Ag and Bag3 physically interact with each other through the zinc-finger of T-Ag and the proline rich domains of Bag3, and this interaction is important for the autophagic degradation of T-Ag. Our observations open a new avenue of research for better understanding of virus-host interaction by investigating the interplay between T-Ag and Bag3, and their impact on the development of JCV-associated diseases.     

A Rapid Deprotection Procedure for Phosphotriester DNA Synthesis

Abstract

An equimolar solution of aldoxime and tetramethylguanidine at 70°C cleaves all base labile protecting groups from oligonucleotides.     

Synthesis of Some Nucleoside Cyclic Ethylene Phosphothionates

Abstract

This communication describes the synthesis of 5′-deoxy-5′-chloro-3′-(2-thio-1,3,2-dioxaphosphorinanyl)thymidine, N⁴,2′,3′-triacetyl-5′-(2-thio-1,3,2-dioxaphosphorinanyl)-1-β-D-arabinosyl-cytosine and N⁴-acetyl-5′-(2-thio-1,3,2-dioxaphosphorinanyl)-1-β-D-arabinosylcytosine.     

Age-Related Modulation of the Effects of Obesity on Gene Expression Profiles of Mouse Bone Marrow and Epididymal Adipocytes

This study aimed to characterize and compare the effects of obesity on gene expression profiles in two distinct adipose depots, epididymal and bone marrow, at two different ages in mice. Alterations in gene expression were analyzed in adipocytes isolated from diet-induced obese (DIO) C57BL/6J male mice at 6 and 14 months of age and from leptin deficient mice (ob/ob) at 6 months of age using microarrays. DIO affected gene expression in both depots at 6 and 14 months, but more genes were altered in epididymal than bone marrow adipocytes at each age and younger mice displayed more changes than older animals. In epididymal adipocytes a total of 2789 (9.6%) genes were differentially expressed at 6-months with DIO, whereas 952 (3.3%) were affected at 14-months. In bone marrow adipocytes, 347 (1.2%) genes were differentially expressed at 6-months with DIO, whereas only 189 (0.66%) were changed at 14-months. 133 genes were altered by DIO in both fat depots at 6-months, and 37 genes at 14-months. Only four genes were altered in both depots at both ages with DIO. Bone marrow adipocytes are less responsive to DIO than epididymal adipocytes and the response of both depots to DIO declines with age. This loss of responsiveness with age is likely due to age-associated changes in expression of genes related to adipogenesis, inflammation and mitochondrial function that are similar to and obscure the changes commonly associated with DIO. Patterns of gene expression were generally similar in epididymal adipocytes from ob/ob and DIO mice; however, several genes were differentially expressed in bone marrow adipocytes from ob/ob and DIO mice, perhaps reflecting the importance of leptin signaling for bone metabolism. In conclusion, obesity affects age-associated alterations in gene expression in both epididymal and bone marrow adipocytes regardless of diet or genetic background.     

Optimal conditions and specificity of interaction of a distinct class of nonhistone chromosomal proteins with DNA.

A subclass of nonhistone chromatin proteins with high DNA affinity has been isolated from rat liver. The interaction of the isolated proteins with DNA in vitro was characterized utilizing a nitrocellulose filter binding technique. The temperature, time, concentration, ionic strength, and pH dependence were characterized. Optimal interaction was observed at 0.19 M naCl, pH 7.5 with a protein to DNA ratio of 13 (w/w). Equilibrium and kinetic competition experiments indicated that these proteins interact optimally with A-T rich and single-stranded DNA. The data also suggest that these proteins might affect the helixcoil transiton of DNA.     

Chronic caffeine consumption increases the number of brain adenosine receptors

Caffeine, a potent central stimulant, is known to competitively inhibit the specific binding of both adenosine and benzodiazepine receptor ligands to brain membranes in vitro. In mice receiving a diet containing non-toxic doses of caffeine (200 or 400 mg/kg diet) for periods up to 40 days, a dose-related increase in the number of binding sites for [3H]-CHA and [3H] DPX was observed in whole brain membranes without modifications of the receptors' affinity. Furthermore, a transitory increase in the number of [3H]-DZP binding sites was observed. These preliminary data seem to confirm the involvement of the adenosine receptors in the mode of action of caffeine and may be relevant to the development of both tolerance and dependence to some of the central effects of this compound.