SHARP1 suppresses breast cancer metastasis by promoting degradation of hypoxia-inducible factors

The molecular determinants of malignant cell behaviours in breast cancer remain only partially understood. Here we show that SHARP1 (also known as BHLHE41 or DEC2) is a crucial regulator of the invasive and metastatic phenotype in triple-negative breast cancer (TNBC), one of the most aggressive types of breast cancer. SHARP1 is regulated by the p63 metastasis suppressor and inhibits TNBC aggressiveness through inhibition of hypoxia-inducible factor 1α (HIF-1α) and HIF-2α (HIFs). SHARP1 opposes HIF-dependent TNBC cell migration in vitro, and invasive or metastatic behaviours in vivo. SHARP1 is required, and sufficient, to limit expression of HIF-target genes. In primary TNBC, endogenous SHARP1 levels are inversely correlated with those of HIF targets. Mechanistically, SHARP1 binds to HIFs and promotes HIF proteasomal degradation by serving as the HIF-presenting factor to the proteasome. This process is independent of pVHL (von Hippel-Lindau tumour suppressor), hypoxia and the ubiquitination machinery. SHARP1 therefore determines the intrinsic instability of HIF proteins to act in parallel to, and cooperate with, oxygen levels. This work sheds light on the mechanisms and pathways by which TNBC acquires invasiveness and metastatic propensity.     

STED microscopy reveals that synaptotagmin remains clustered after synaptic vesicle exocytosis

Synaptic transmission is mediated by neurotransmitters that are stored in synaptic vesicles and released by exocytosis upon activation. The vesicle membrane is then retrieved by endocytosis, and synaptic vesicles are regenerated and re-filled with neurotransmitter. Although many aspects of vesicle recycling are understood, the fate of the vesicles after fusion is still unclear. Do their components diffuse on the plasma membrane, or do they remain together? This question has been difficult to answer because synaptic vesicles are too small (approximately 40 nm in diameter) and too densely packed to be resolved by available fluorescence microscopes. Here we use stimulated emission depletion (STED) to reduce the focal spot area by about an order of magnitude below the diffraction limit, thereby resolving individual vesicles in the synapse. We show that synaptotagmin I, a protein resident in the vesicle membrane, remains clustered in isolated patches on the presynaptic membrane regardless of whether the nerve terminals are mildly active or intensely stimulated. This suggests that at least some vesicle constituents remain together during recycling. Our study also demonstrates that questions involving cellular structures with dimensions of a few tens of nanometres can be resolved with conventional far-field optics and visible light.     

Therapeutic silencing of an endogenous gene by systemic administration of modified siRNAs

RNA interference (RNAi) holds considerable promise as a therapeutic approach to silence disease-causing genes, particularly those that encode so-called 'non-druggable' targets that are not amenable to conventional therapeutics such as small molecules, proteins, or monoclonal antibodies. The main obstacle to achieving in vivo gene silencing by RNAi technologies is delivery. Here we show that chemically modified short interfering RNAs (siRNAs) can silence an endogenous gene encoding apolipoprotein B (apoB) after intravenous injection in mice. Administration of chemically modified siRNAs resulted in silencing of the apoB messenger RNA in liver and jejunum, decreased plasma levels of apoB protein, and reduced total cholesterol. We also show that these siRNAs can silence human apoB in a transgenic mouse model. In our in vivo study, the mechanism of action for the siRNAs was proven to occur through RNAi-mediated mRNA degradation, and we determined that cleavage of the apoB mRNA occurred specifically at the predicted site. These findings demonstrate the therapeutic potential of siRNAs for the treatment of disease.     

Two new species of Neosophia Guimarães, 1982 and first description of female of Neoeuantha sabroskyi Guimarães, 1982 (Diptera: Tachinidae)

Neosophia Guimarães is a monotypic genus with Neotropical distribution that belongs to the tribe Sophiini. Neosophia guimaraesi sp. nov. from Amazonas, Brazil, and Neosophia bispinosa sp. nov. from Costa Rica are new species described for this genus. The female of Neoeuantha sabroskyi Guimarães, 1982 is described for the first time. First-instar larvae and illustrations of the female terminalia are described and illustrated for both new species.     

Soft System Dynamics Methodology in Action: A study of the Problem of Citizen Insecurity in an Argentinean Province

This paper illustrates an application of soft system dynamics methodology (SSDM). SSDM arose as a fusion of two well-known methodologies in the systems movement: system dynamics (SD) and soft systems methodology (SSM). SSDM includes 10 steps to orchestrate and implant change in social systems, based on a multimethodological and multiparadigmatic approach as an outcome of the combination of the mentioned methodologies. After a brief introduction, the paper starts by briefly explaining SSM and SD, their stages and their problematical issues as systemic methodologies, then goes on to explain SSDM, its philosophical roots and stages, ending with a comparison among the three. It then introduces the citizen insecurity problem in Argentina, specifically in Mendoza Province, where SSDM was applied to analyze this issue. The paper concludes with an explanation of the learning points that arose from the use of SSDM in this study and suggestions for further research on citizen security and SSDM.