Mutation Rates of TGFBR2 and ACVR2 Coding Microsatellites in Human Cells with Defective DNA Mismatch Repair

Microsatellite instability promotes colonic tumorigenesis through generating frameshift mutations at coding microsatellites of tumor suppressor genes, such as TGFBR2 and ACVR2. As a consequence, signaling through these TGFβ family receptors is abrogated in DNA Mismatch repair (MMR)-deficient tumors. How these mutations occur in real time and mutational rates of these human coding sequences have not previously been studied. We utilized cell lines with different MMR deficiencies (hMLH1−/−, hMSH6−/−, hMSH3−/−, and MMR-proficient) to determine mutation rates. Plasmids were constructed in which exon 3 of TGFBR2 and exon 10 of ACVR2 were cloned +1 bp out of frame, immediately after the translation initiation codon of an enhanced GFP (EGFP) gene, allowing a −1 bp frameshift mutation to drive EGFP expression. Mutation-resistant plasmids were constructed by interrupting the coding microsatellite sequences, preventing frameshift mutation. Stable cell lines were established containing portions of TGFBR2 and ACVR2, and nonfluorescent cells were sorted, cultured for 7–35 days, and harvested for flow cytometric mutation detection and DNA sequencing at specific time points. DNA sequencing revealed a −1 bp frameshift mutation (A9 in TGFBR2 and A7 in ACVR2) in the fluorescent cells. Two distinct fluorescent populations, M1 (dim, representing heteroduplexes) and M2 (bright, representing full mutants) were identified, with the M2 fraction accumulating over time. hMLH1 deficiency revealed 11 (5.91×10−4) and 15 (2.18×10−4) times higher mutation rates for the TGFBR2 and ACVR2 microsatellites compared to hMSH6 deficiency, respectively. The mutation rate of the TGFBR2 microsatellite was ∼3 times higher in both hMLH1 and hMSH6 deficiencies than the ACVR2 microsatellite. The −1 bp frameshift mutation rates of TGFBR2 and ACVR2 microsatellite sequences are dependent upon the human MMR background

The utility of human security: Sovereignty and humanitarian intervention

'Human security' is a promising but still underdeveloped paradigmatic approach to understanding contemporary security politics. We argue that tension between those embracing the politics of development and those supporting the human security paradigm has intensified because the transnational dimensions embodied within the latter approach have been under-assessed. The idea of 'threat' also needs to be identified with more precision for the human security concept to accrue analytical credibility. We focus on how transnational behaviour addresses the central human security problems of vulnerability and immediacy. Human security's utility for confronting crisis is also evaluated via the application of two case studies of humanitarian intervention: the 1994 multinational operation in Haiti and the 1999 intervention in East Timor. We conclude that, while general security politics includes both domestic and international issues, human security allows us to transcend sovereign prerogatives and to address emerging transregional threats more effectively

O enquadramento das Missões de Paz (PKO) nas teorias da guerra e de polícia

A clareza original do que sejam as operações de manutenção, ou Missões de Paz - PKO - já não existe, se é que algum dia ela de fato existiu. No decorrer desse artigo Busca-se enquadrar as PKO nas teorias de guerra e de polícia, com base no entendimento sobre força e violência, uso da força, guerra e paz. Ao final, há algumas observações sobre a utilidade desses enquadramentos.<br>The original meaning of what are the Peacekeeping Operations - PKO - no longer exists, that is, if some day it really existed. This article tries to fit the PKO in the theories of war and police, based on the comprehension of strength and violence, the use of strength, war, and peace. In conclusion, there are some observations about the utility of those allocations