Polar relaxation by dynein-mediated removal of cortical myosin II

Nearly 6 decades ago, Lewis Wolpert proposed the relaxation of the polar cell cortex by the radial arrays of astral microtubules as a mechanism for cleavage furrow induction (White and Borisy, 1983; Wolpert, 1960). While this mechanism has remained controversial (Rappaport, 1996), recent work has provided evidence for polar relaxation by astral microtubules (Chen et al., 2008; Dechant and Glotzer, 2003; Foe and Dassow, 2008; Murthy and Wadsworth, 2008; Werner et al., 2007), although its molecular mechanisms remain elusive. Here, using C. elegans embryos, we show that polar relaxation is achieved through dynein-mediated removal of myosin II from the polar cortexes. Mutants that position centrosomes closer to the polar cortex accelerated furrow induction whereas suppression of dynein activity delayed furrowing. We provide evidence that dynein-mediated removal of myosin II from the polar cortexes triggers cortical flow towards the cell equator, which induces the assembly of the actomyosin contractile ring. These studies for the first time provide a molecular basis for the aster-dependent polar relaxation, which works in parallel with equatorial stimulation to promote robust cytokinesis

Pathophysiologic correlates of exercise intolerance in adults with pulmonary hypertension and congenital heart disease

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Aerospace Medicine and Biology: A continuing bibliography with indexes, supplement 182, July 1978

This bibliography lists 165 reports, articles, and other documents introduced into the NASA scientific and technical information system in June 1978

Multiple knockout mouse models reveal lincRNAs are required for life and brain development

Many studies are uncovering functional roles for long noncoding RNAs (lncRNAs), yet few have been tested for in vivo relevance through genetic ablation in animal models. To investigate the functional relevance of lncRNAs in various physiological conditions, we have developed a collection of 18 lncRNA knockout strains in which the locus is maintained transcriptionally active. Initial characterization revealed peri- and postnatal lethal phenotypes in three mutant strains (Fendrr, Peril, and Mdgt), the latter two exhibiting incomplete penetrance and growth defects in survivors. We also report growth defects for two additional mutant strains (linc–Brn1b and linc–Pint). Further analysis revealed defects in lung, gastrointestinal tract, and heart in Fendrr−/− neonates, whereas linc–Brn1b−/− mutants displayed distinct abnormalities in the generation of upper layer II–IV neurons in the neocortex. This study demonstrates that lncRNAs play critical roles in vivo and provides a framework and impetus for future larger-scale functional investigation into the roles of lncRNA molecules. DOI: http://dx.doi.org/10.7554/eLife.01749.00

Transformed epithelia trigger non-tissue-autonomous tumor suppressor response by adipocytes via activation of toll and Eiger/TNF signaling

High tumor burden is associated with increased levels of circulating inflammatory cytokines that influence the pathophysiology of the tumor and its environment. The cellular and molecular events mediating the organismal response to a growing tumor are poorly understood. Here, we report a bidirectional crosstalk between epithelial tumors and the fat body—a peripheral immune tissue—in Drosophila. Tumors trigger a systemic immune response through activation of Eiger/TNF signaling, which leads to Toll pathway upregulation in adipocytes. Reciprocally, Toll elicits a non-tissue-autonomous program in adipocytes, which drives tumor cell death. Hemocytes play a critical role in this system by producing the ligands Spätzle and Eiger, which are required for Toll activation in the fat body and tumor cell death. Altogether, our results provide a paradigm for a long-range tumor suppression function of adipocytes in Drosophila, which may represent an evolutionarily conserved mechanism in the organismal response to solid tumors