Strategies for Interdisciplinary Human Gene Editing Research: Insights from a Swiss Project.

CRISPR gene editing is a cutting-edge technology that has advanced tremendously in recent years. The first clinical CRISPR applications have been approved, and more gene editing therapies are to be expected in human medicine. Consequently, continuous basic research is needed to assess possibilities and prime future clinical applications.

Mammalian oocytes store proteins for the early embryo on cytoplasmic lattices.

Mammalian oocytes are filled with poorly understood structures called cytoplasmic lattices. First discovered in the 1960s and speculated to correspond to mammalian yolk, ribosomal arrays, or intermediate filaments, their function has remained enigmatic to date. Here, we show that cytoplasmic lattices are sites where oocytes store essential proteins for early embryonic development.

Volumetric morphometry reveals spindle width as the best predictor of mammalian spindle scaling.

The function of cellular structures at the mesoscale is dependent on their geometry and proportionality to cell size. The mitotic spindle is a good example why length and shape of intracellular organelles matter. Spindle length determines the distance over which chromosomes will segregate, and spindle shape ensures bipolarity.

Parental genome unification is highly error-prone in mammalian embryos.

Most human embryos are aneuploid. Aneuploidy frequently arises during the early mitotic divisions of the embryo, but its origin remains elusive. Human zygotes that cluster their nucleoli at the pronuclear interface are thought to be more likely to develop into healthy euploid embryos.

Two mechanisms drive pronuclear migration in mouse zygotes.

A new life begins with the unification of the maternal and paternal chromosomes upon fertilization. The parental chromosomes first become enclosed in two separate pronuclei near the surface of the fertilized egg. The mechanisms that then move the pronuclei inwards for their unification are only poorly understood in mammals.

Aneuploidy in human eggs: contributions of the meiotic spindle.

Human eggs frequently contain an incorrect number of chromosomes, a condition termed aneuploidy. Aneuploidy affects ∼10-25% of eggs in women in their early 30s, and more than 50% of eggs from women over 40. Most aneuploid eggs cannot develop to term upon fertilization, making aneuploidy in eggs a leading cause of miscarriages and infertility.

Proteomic Profiling of Microtubule Self-organization in M-phase.

Microtubules (MTs) and associated proteins can self-organize into complex structures such as the bipolar spindle, a process in which RanGTP plays a major role. Addition of RanGTP to M-phase egg extracts promotes the nucleation and self-organization of MTs into asters and bipolar-like structures in the absence of centrosomes or chromosomes. We show here that the complex proteome of these RanGTP-induced MT assemblies is similar to that of mitotic spindles.

The sequential activation of the mitotic microtubule assembly pathways favors bipolar spindle formation.

Centrosome maturation is the process by which the duplicated centrosomes recruit pericentriolar components and increase their microtubule nucleation activity before mitosis. The role of this process in cells entering mitosis has been mostly related to the separation of the duplicated centrosomes and thereby to the assembly of a bipolar spindle. However, spindles can form without centrosomes.

Allosteric inhibition of Aurora-A kinase by a synthetic vNAR domain.

The vast majority of clinically approved protein kinase inhibitors target the ATP-binding pocket directly. Consequently, many inhibitors have broad selectivity profiles and most have significant off-target effects. Allosteric inhibitors are generally more selective, but are difficult to identify because allosteric binding sites are often unknown or poorly characterized.

From meiosis to mitosis - the sperm centrosome defines the kinetics of spindle assembly after fertilization in Xenopus.

Bipolar spindle assembly in the vertebrate oocyte relies on a self-organization chromosome-dependent pathway. Upon fertilization, the male gamete provides a centrosome, and the first and subsequent embryonic divisions occur in the presence of duplicated centrosomes that act as dominant microtubule organizing centres (MTOCs). The transition from meiosis to embryonic mitosis involves a necessary adaptation to integrate the dominant chromosome-dependent pathway with the centrosomes to form the bipolar spindle.

The RanGTP Pathway: From Nucleo-Cytoplasmic Transport to Spindle Assembly and Beyond.

The small GTPase Ran regulates the interaction of transport receptors with a number of cellular cargo proteins. The high affinity binding of the GTP-bound form of Ran to import receptors promotes cargo release, whereas its binding to export receptors stabilizes their interaction with the cargo. This basic mechanism linked to the asymmetric distribution of the two nucleotide-bound forms of Ran between the nucleus and the cytoplasm generates a switch like mechanism controlling nucleo-cytoplasmic transport.

Aurora-A-Dependent Control of TACC3 Influences the Rate of Mitotic Spindle Assembly.

The essential mammalian gene TACC3 is frequently mutated and amplified in cancers and its fusion products exhibit oncogenic activity in glioblastomas. TACC3 functions in mitotic spindle assembly and chromosome segregation. In particular, phosphorylation on S558 by the mitotic kinase, Aurora-A, promotes spindle recruitment of TACC3 and triggers the formation of a complex with ch-TOG-clathrin that crosslinks and stabilises kinetochore microtubules.

XTACC3-XMAP215 association reveals an asymmetric interaction promoting microtubule elongation.

chTOG is a conserved microtubule polymerase that catalyses the addition of tubulin dimers to promote microtubule growth. chTOG interacts with TACC3, a member of the transforming acidic coiled-coil (TACC) family. Here we analyse their association using the Xenopus homologues, XTACC3 (TACC3) and XMAP215 (chTOG), dissecting the mechanism by which their interaction promotes microtubule elongation during spindle assembly.

High-resolution cryo-electron microscopy structures of murine norovirus 1 and rabbit hemorrhagic disease virus reveal marked flexibility in the receptor binding domains.

Our previous structural studies on intact, infectious murine norovirus 1 (MNV-1) virions demonstrated that the receptor binding protruding (P) domains are lifted off the inner shell of the virus. Here, the three-dimensional (3D) reconstructions of recombinant rabbit hemorrhagic disease virus (rRHDV) virus-like particles (VLPs) and intact MNV-1 were determined to approximately 8-A resolution. rRHDV also has a raised P domain, and therefore, this conformation is independent of infectivity and genus.