Botian Liu

Mesoderm Inducer in Xenopus Like1, a paired-type homeobox transcription factor induced by TGF-β family of ligands is required for early embryonic specification of mesoderm and endoderm. Retrovirally transduced Mixl1 is reported to induce acute myelogenous leukemia with a high penetrance. But the mechanistic underpinnings of MIXL1 mediated leukemogenesis are unknown. Here, we establish the protooncogene c-REL to be a transcriptional target of MIXL1 by genome wide chromatin immune precipitation. Accordingly, expression of c-REL and its downstream targets BCL2L1 and BCL2A2 are elevated in MIXL1 expressing cells. Notably, MIXL1 regulates c-REL through a zinc finger binding motif, potentially by a MIXL1-Zinc finger protein transcriptional complex. Furthermore, MIXL1 expression is detected in the cancer genome atlas AML samples in a pattern mutually exclusive from that of HOXA9, CDX2 and HLX suggesting the existence of a core, yet distinct HOX transcriptional program. Finally, we demonstrate MIXL1 to be induced by BMP4 and not TGF-β in primary human hematopoietic stem and progenitor cells. Consequently, MIXL1 expressing AML cells are preferentially sensitive to the BMPR1 kinase inhibitor LDN-193189. These findings support the existence of a novel MIXL1-c REL mediated survival axis in AML that can be targeted by BMPR1 inhibitors..

Kant and Butler have a sharp methodological conflict in justifying moral obligations. While Kant argues that moral obligations can only be grounded in a prior justifications rather than in anything empirical, Joseph Butler grounds moral obligations in the empirical knowledge of human beings. Despite the apparent radical difference, I argue that Kant agrees with Butler that moral obligations must be grounded in the understanding of human beings. They, however, fundamentally disagree about human nature, which generates their methodological conflict in studying morality. For Kant, the essential attribute for human beings is autonomy, which presupposes independence from any particular experience. In contrast, Butler understands human nature as a system that includes different particular experience. Although there is no conclusive answer of the correct understanding of human nature, I suggest that Butler’s account of moral obligations is a plausible one that can be considered as a counterexample to Kant’s account.

To better determine the history of modern birds, we performed a genome-scale phylogenetic analysis of 48 species representing all orders of Neoaves using phylogenomic methods created to handle genome-scale data.We recovered a highly resolved tree that confirms previously controversial sister or close relationships.We identified the first divergence in Neoaves, two groups we named Passerea and Columbea, representing independent lineages of diverse and convergently evolved land and water bird species. Among Passerea, we infer the common ancestor of core landbirds to have been an apex predator and confirm independent gains of vocal learning. Among Columbea, we identify pigeons and flamingoes as belonging to sister clades. Even with whole genomes, some of the earliest branches in Neoaves proved challenging to resolve, which was best explained by massive protein-coding sequence convergence and high levels of incomplete lineage sorting that occurred during a rapid radiation after the Cretaceous-Paleogene mass extinction event about 66 million years ago.

© 2015 Wiley Periodicals, Inc. Cell fragments devoid of the nucleus and major organelles are found in physiology and pathology, for example platelets derived from megakaryocytes, and cell fragments from white blood cells and glioma cells. Platelets exhibit active chemotaxis. Fragments from white blood cells display chemotaxis, phagocytosis, and bactericidal functions. Signaling mechanisms underlying migration of cell fragments are poorly understood. Here we used fish keratocyte fragments and demonstrated striking differences in signal transduction in migration of cell fragments and parental cells in a weak electric field. cAMP or cGMP agonists completely abolished directional migration of fragments, but had no effect on parental cells. The inhibition effects were prevented by pre-incubating with cAMP and cGMP antagonists. Blocking cAMP and cGMP downstream signaling by inhibition of PKA and PKG also recovered fragment galvanotaxis. Both perturbations confirmed that the inhibitory effect was mediated by cAMP or cGMP signaling. Inhibition of cathode signaling with PI3K inhibitor LY294002 also prevented the effects of cAMP or cGMP agonists. Our results suggest that cAMP and cGMP are essential for galvanotaxis of cell fragments, in contrast to the signaling mechanisms in parental cells.