Modifications in host cell cytoskeleton structure and function mediated by intracellular HIV-1 Tat protein are greatly dependent on the second coding exon.

The human immunodeficiency virus type 1 (HIV-1) regulator Tat is essential for viral replication because it achieves complete elongation of viral transcripts. Tat can be released to the extracellular space and taken up by adjacent cells, exerting profound cytoskeleton rearrangements that lead to apoptosis. In contrast, intracellular Tat has been described as protector from apoptosis. Tat gene is composed by two coding exons that yield a protein of 101 amino acids (aa). First exon (1-72aa) is sufficient for viral transcript elongation and second exon (73-101 aa) appears to contribute to non-transcriptional functions. We observed that Jurkat cells stably expressing intracellular Tat101 showed gene expression deregulation 4-fold higher than cells expressing Tat72. Functional experiments were performed to evaluate the effect of this deregulation. First, NF-kappaB-, NF-AT- and Sp1-dependent transcriptional activities were greatly enhanced in Jurkat-Tat101, whereas Tat72 induced milder but efficient activation. Second, cytoskeleton-related functions as cell morphology, proliferation, chemotaxis, polarization and actin polymerization were deeply altered in Jurkat-Tat101, but not in Jurkat-Tat72. Finally, expression of several cell surface receptors was dramatically impaired by intracellular Tat101 but not by Tat72. Consequently, these modifications were greatly dependent on Tat second exon and they could be related to the anergy observed in HIV-1-infected T cells.

Highly sensitive molecular diagnosis of prostate cancer using surplus material washed off from biopsy needles.

INTRODUCTION: Currently, final diagnosis of prostate cancer (PCa) is based on histopathological analysis of needle biopsies, but this process often bears uncertainties due to small sample size, tumour focality and pathologist's subjective assessment. METHODS: Prostate cancer diagnostic signatures were generated by applying linear discriminant analysis to microarray and real-time RT-PCR (qRT-PCR) data from normal and tumoural prostate tissue samples. Additionally, after removal of biopsy tissues, material washed off from transrectal biopsy needles was used for molecular profiling and discriminant analysis. RESULTS: Linear discriminant analysis applied to microarray data for a set of 318 genes differentially expressed between non-tumoural and tumoural prostate samples produced 26 gene signatures, which classified the 84 samples used with 100% accuracy. To identify signatures potentially useful for the diagnosis of prostate biopsies, surplus material washed off from routine biopsy needles from 53 patients was used to generate qRT-PCR data for a subset of 11 genes. This analysis identified a six-gene signature that correctly assigned the biopsies as benign or tumoural in 92.6% of the cases, with 88.8% sensitivity and 96.1% specificity. CONCLUSION: Surplus material from prostate needle biopsies can be used for minimal-size gene signature analysis for sensitive and accurate discrimination between non-tumoural and tumoural prostates, without interference with current diagnostic procedures. This approach could be a useful adjunct to current procedures in PCa diagnosis.

Protein disorder in the centrosome correlates with complexity in cell types number.

Here we study the properties and the evolution of proteins that constitute the Centrosome, the complex molecular assembly that regulates the division and differentiation of animal cells. We found that centrosomal proteins are predicted to be significantly enriched in disordered and coiled-coil regions, more phosphorylated and longer than control proteins of the same organism. Interestingly, the ratio of these properties in centrosomal and control proteins tends to increase with the number of cell-types. We reconstructed indels evolution, finding that indels significantly increase disorder in both centrosomal and control proteins, at a rate that is typically larger along branches associated with a large growth in cell-types number, and larger for centrosomal than for control proteins. Substitutions show a similar trend for coiled-coil, but they contribute less to the evolution of disorder. Our results suggest that the increase in cell-types number in animal evolution is correlated with the gain of disordered and coiled-coil regions in centrosomal proteins, establishing a connection between organism and molecular complexity. We argue that the structural plasticity conferred to the Centrosome by disordered regions and phosphorylation plays an important role in its mechanical properties and its regulation in space and time.