Implantation and Gastrulation Abnormalities Characterize Early Embryonic Lethal Mouse Lines [preprint]

The period of development between the zygote and embryonic day 9.5 in mice includes multiple developmental milestones essential for embryogenesis. The preeminence of this period of development has been illustrated in loss of function studies conducted by the International Mouse Phenotyping Consortium (IMPC) which have shown that close to one third of all mouse genes are essential for survival to weaning age and a significant number of mutations cause embryo lethality before E9.5. Here we report a systematic analysis of 21 pre-E9.5 lethal lines generated by the IMPC. Analysis of pre- and post-implantation embryos revealed that the majority of the lines exhibit mutant phenotypes that fall within a window of development between implantation and gastrulation with few pre-implantation and no post-gastrulation phenotypes. Our study provides multiple genetic inroads into the molecular mechanisms that control early mammalian development and the etiology of human disease, in particular, the genetic bases of infertility and pregnancy loss. We propose a strategy for an efficient assessment of early embryonic lethal mutations that can be used to assign phenotypes to developmental milestones and outline the time of lethality

The Zn-finger domain of MdmX suppresses cancer progression by promoting genome stability in p53-mutant cells

The MDMX (MDM4) oncogene is amplified or overexpressed in a significant percentage of human tumors. MDMX is thought to function as an oncoprotein by binding p53 tumor suppressor protein to inhibit p53-mediated transcription, and by complexing with MDM2 oncoprotein to promote MDM2-mediated degradation of p53. However, down-regulation or loss of functional MDMX has also been observed in a variety of human tumors that are mutated for p53, often correlating with more aggressive cancers and a worse patient prognosis. We have previously reported that endogenous levels of MdmX can suppress proliferation and promote pseudo-bipolar mitosis in primary and tumor cells derived from p53-deficient mice, and that MdmX-p53 double deficient mice succumb to spontaneously formed tumors more rapidly than p53-deficient mice. These results suggest that the MdmX oncoprotein may act as a tumor-suppressor in cancers with compromised p53 function. By using orthotopic transplantation and lung colonization assays in mice we now establish a p53-independent anti-oncogenic role for MdmX in tumor progression. We also demonstrate that the roles of MdmX in genome stability and in proliferation are two distinct functions encoded by the separate MdmX protein domains. The central Zn-finger domain suppresses multipolar mitosis and chromosome loss, whereas the carboxy-terminal RING domain suppresses proliferation of p53-deficient cells. Furthermore, we determine that it is the maintenance of genome stability that underlies MdmX role in suppression of tumorigenesis in hyperploid p53 mutant tumors. Our results offer a rationale for the increased metastatic potential of p53 mutant human cancers with aberrant MdmX function and provide a caveat for the application of anti-MdmX treatment of tumors with compromised p53 activity

LMDA Review, volume 12, issue 1

Contents include: Re-Viewing Denver, University & Student Caucus, Keynote Ashara Ekundayo, Denver Theatre Artists on Local Theatre Ecology, Workshop Sessions Round 1: Dramaturgy & Architecture, Dramaturgical Voices Inside the Theatre, Dramaturgy/Making a Life, Workshop Sessions Round 2: New Play Festivals, Dramaturgical Voices Outside the Theatre, Educational Theatre, TheatreFest Playwrights, Advocacy, Elliott Hayes Award Winner Judith Rudakoff, and Regional VP Update.https://soundideas.pugetsound.edu/lmdareview/1024/thumbnail.jp

Review: The Newsletter of Literary Managers and Dramaturgs of the Americas, volume 11, issue 3

Contents include: Section I: Re-Viewing Denver; The Conference in Detail; Dramaturgical Voices Outside the Theatre; Section II: Articles & Announcements. Issue editor: Gretchen Haleyhttps://soundideas.pugetsound.edu/lmdareview/1048/thumbnail.jp

Design of Functionalized Lipids and Evidence for Their Binding to Photosystem II Core Complex by Oxygen Evolution Measurements, Atomic Force Microscopy, and Scanning Near-Field Optical Microscopy

AbstractPhotosystem II core complex (PSII CC) absorbs light energy and triggers a series of electron transfer reactions by oxidizing water while producing molecular oxygen. Synthetic lipids with different alkyl chains and spacer lengths bearing functionalized headgroups were specifically designed to bind the QB site and to anchor this large photosynthetic complex (240 kDa) in order to attempt two-dimensional crystallization. Among the series of different compounds that have been tested, oxygen evolution measurements have shown that dichlorophenyl urea (DCPU) binds very efficiently to the QB site of PSII CC, and therefore, that moiety has been linked covalently to the headgroup of synthetic lipids. The analysis of the monolayer behavior of these DCPU-lipids has allowed us to select ones bearing long spacers for the anchoring of PSII CC. Oxygen evolution measurements demonstrated that these long-spacer DCPU-lipids specifically bind to PSII CC and inhibit electron transfer. With the use of atomic force microscopy (AFM) and scanning near-field optical microscopy (SNOM), it was possible to visualize domains of PSII CC bound to DCPU-lipid monolayers. SNOM imaging has enabled us to confirm that domains observed by AFM were composed of PSII CC. Indeed, the SNOM topography images presented similar domains as those observed by AFM, but in addition, it allowed us to determine that these domains are fluorescent. Electron microscopy of these domains, however, has shown that the bound PSII CC was not crystalline

Rlim-Dependent and -Independent Pathways for X Chromosome Inactivation in Female ESCs

During female mouse embryogenesis, two forms of X chromosome inactivation (XCI) ensure dosage compensation from sex chromosomes. Beginning at the four-cell stage, imprinted XCI (iXCI) exclusively silences the paternal X (Xp), and this pattern is maintained in extraembryonic cell types. Epiblast cells, which give rise to the embryo proper, reactivate the Xp (XCR) and undergo a random form of XCI (rXCI) around implantation. Both iXCI and rXCI depend on the long non-coding RNA Xist. The ubiquitin ligase RLIM is required for iXCI in vivo and occupies a central role in current models of rXCI. Here, we demonstrate the existence of Rlim-dependent and Rlim-independent pathways for rXCI in differentiating female ESCs. Upon uncoupling these pathways, we find more efficient Rlim-independent XCI in ESCs cultured under physiological oxygen conditions. Our results revise current models of rXCI and suggest that caution must be taken when comparing XCI studies in ESCs and mice