HIV-1 Reverse Transcriptase Promotes Tumor Growth and Metastasis Formation via ROS-Dependent Upregulation of Twist.

HIV-induced immune suppression results in the high prevalence of HIV/AIDS-associated malignancies including Kaposi sarcoma, non-Hodgkin lymphoma, and cervical cancer. HIV-infected people are also at an increased risk of "non-AIDS-defining" malignancies not directly linked to immune suppression but associated with viral infections. Their incidence is increasing despite successful antiretroviral therapy. The mechanism behind this phenomenon remains unclear. Here, we obtained daughter clones of murine mammary gland adenocarcinoma 4T1luc2 cells expressing consensus reverse transcriptase of HIV-1 subtype A FSU_A strain (RT_A) with and without primary mutations of drug resistance. In in vitro tests, mutations of resistance to nucleoside inhibitors K65R/M184V reduced the polymerase, and to nonnucleoside inhibitors K103N/G190S, the RNase H activities of RT_A. Expression of these RT_A variants in 4T1luc2 cells led to increased production of the reactive oxygen species (ROS), lipid peroxidation, enhanced cell motility in the wound healing assay, and upregulation of expression of Vimentin and Twist. These properties, particularly, the expression of Twist, correlated with the levels of expression RT_A and/or the production of ROS. When implanted into syngeneic BALB/C mice, 4T1luc2 cells expressing nonmutated RT_A demonstrated enhanced rate of tumor growth and increased metastatic activity, dependent on the level of expression of RT_A and Twist. No enhancement was observed for the clones expressing mutated RT_A variants. Plausible mechanisms are discussed involving differential interactions of mutated and nonmutated RTs with its cellular partners involved in the regulation of ROS. This study establishes links between the expression of HIV-1 RT, production of ROS, induction of EMT, and enhanced propagation of RT-expressing tumor cells. Such scenario can be proposed as one of the mechanisms of HIV-induced/enhanced carcinogenesis not associated with immune suppression.

DisProt 7.0: a major update of the database of disordered proteins.

The Database of Protein Disorder (DisProt, URL: www.disprot.org) has been significantly updated and upgraded since its last major renewal in 2007. The current release holds information on more than 800 entries of IDPs/IDRs, i.e. intrinsically disordered proteins or regions that exist and function without a well-defined three-dimensional structure. We have re-curated previous entries to purge DisProt from conflicting cases, and also upgraded the functional classification scheme to reflect continuous advance in the field in the past 10 years or so. We define IDPs as proteins that are disordered along their entire sequence, i.e. entirely lack structural elements, and IDRs as regions that are at least five consecutive residues without well-defined structure. We base our assessment of disorder strictly on experimental evidence, such as X-ray crystallography and nuclear magnetic resonance (primary techniques) and a broad range of other experimental approaches (secondary techniques). Confident and ambiguous annotations are highlighted separately. DisProt 7.0 presents classified knowledge regarding the experimental characterization and functional annotations of IDPs/IDRs, and is intended to provide an invaluable resource for the research community for a better understanding structural disorder and for developing better computational tools for studying disordered proteins.

Identification of a Non-Pentapeptide Region Associated with Rapid Mycobacterial Evolution.

A large portion of the coding capacity of Mycobacterium tuberculosis is devoted to the production of proteins containing several copies of the pentapeptide-2 repeat, namely the PE/PPE_MPTR proteins. Protein domain repeats have a variety of binding properties and are involved in protein-protein interactions as well as binding to other ligands such as DNA and RNA. They are not as common in prokaryotes, compared to eukaryotes, but the enrichment of pentapeptide-2 repeats in Mycobacteria constitutes an exception to that rule. The genes encoding the PE/PPE_MPTR proteins have undergone many rearrangements and here we have identified the expansion patterns across the Mycobacteria. We have performed a reclassification of the PE/PPE_MPTR proteins using cohesive regions rather than sparse domain architectures. It is clear that these proteins have undergone large insertions of several pentapeptide-2 domains appearing adjacent to one another in a repetitive pattern. Further, we have identified a non-pentapeptide motif associated with rapid mycobacterial evolution. The sequence composition of this region suggests a different structure compared to pentapeptide-2 repeats. By studying the evolution of the PE/PPE_MPTR proteins, we have distinguished features pertaining to tuberculosis-inducing species. Further studies of the non-pentapeptide region associated with repeat expansions promises to shed light on the pathogenicity of Mycobacterium tuberculosis.

Shotgun proteomics to unravel marine mussel (Mytilus edulis) response to long-term exposure to low salinity and propranolol in a Baltic Sea microcosm.

Pharmaceuticals, among them the ß-adrenoceptor blocker propranolol, are an important group of environmental contaminants reported in European waters. Laboratory exposure to pharmaceuticals on marine species has been performed without considering the input of the ecosystem flow. To unravel the ecosystem response to long-term exposure to propranolol we have performed long-term exposure to propranolol and low salinity in microcosms. We applied shotgun proteomic analysis to gills of Mytilus edulis from those Baltic Sea microcosms and identified 2071 proteins with a proteogenomic strategy. The proteome profiling patterns from the 587 highly reproductive proteins among groups define salinity as a key factor in the mussel's response to propranolol. Exposure at low salinity drives molecular mechanisms of adaptation based on a decrease in the abundance of several cytoskeletal proteins, signalling and intracellular membrane trafficking pathway combined with a response towards the maintenance of transcription and translation. The exposure to propranolol combined with low salinity modulates the expression of structural proteins including cilia functions and decreases the expression of membrane protein transporters. This study reinforces the environment concerns of the impact of low salinity in combination with anthropogenic pollutants and anticipates critical physiological conditions for the survival of the blue mussel in the northern areas. BIOLOGICAL SIGNIFICANCE: Applying shotgun proteomic analysis to M. edulis gills samples from a long-term microcosm exposure to propranolol and following a proteogenomic identification strategy, we have identified 2071 proteins. The proteomic analysis unrevealed which molecular mechanisms drive the adaptation to low salinity stress and how salinity modulates the effects of exposure to propranolol. These results reinforce the idea of the impact of low salinity in combination with anthropogenic pollutants and anticipate critical physiological condition.