Satellite DNA shapes dictate pericentromere packaging in female meiosis.

The abundance and sequence of satellite DNA at and around centromeres is evolving rapidly despite the highly conserved and essential process through which the centromere directs chromosome inheritance. The impact of such rapid evolution is unclear. Here we find that sequence-dependent DNA shape dictates packaging of pericentromeric satellites in female meiosis through a conserved DNA-shape-recognizing chromatin architectural protein, high mobility group AT-hook 1 (HMGA1).

Centromere innovations within a mouse species.

Mammalian centromeres direct faithful genetic inheritance and are typically characterized by regions of highly repetitive and rapidly evolving DNA. We focused on a mouse species, that we found has evolved to house centromere-specifying centromere protein-A (CENP-A) nucleosomes at the nexus of a satellite repeat that we identified and termed π-satellite (π-sat), a small number of recruitment sites for CENP-B, and short stretches of perfect telomere repeats. One chromosome, however, houses a radically divergent centromere harboring ~6 mega-base pairs of a homogenized π-sat-related repeat, π-sat, that contains >20,000 functional CENP-B boxes.

Mapping PTBP2 binding in human brain identifies SYNGAP1 as a target for therapeutic splice switching.

Alternative splicing of neuronal genes is controlled partly by the coordinated action of polypyrimidine tract binding proteins (PTBPs). While PTBP1 is ubiquitously expressed, PTBP2 is predominantly neuronal. Here, we define the PTBP2 footprint in the human transcriptome using brain tissue and human induced pluripotent stem cell-derived neurons (iPSC-neurons).

Epigenetic, genetic and maternal effects enable stable centromere inheritance.

Centromeres are defined epigenetically by the histone H3 variant CENP-A. The propagation cycle by which pre-existing CENP-A nucleosomes serve as templates for nascent assembly predicts the epigenetic memory of weakened centromeres. Using a mouse model with reduced levels of CENP-A nucleosomes, we find that an embryonic plastic phase precedes epigenetic memory through development.

Gene replacement strategies validate the use of functional tags on centromeric chromatin and invalidate an essential role for CENP-A.

Functional tags are ubiquitous in cell biology, and for studies of one chromosomal locus, the centromere, tags have been remarkably useful. The centromere directs chromosome inheritance at cell division. The location of the centromere is defined by a histone H3 variant, CENP-A.

The unique kind of human artificial chromosome: Bypassing the requirement for repetitive centromere DNA.

Centromeres are essential components of all eukaryotic chromosomes, including artificial/synthetic ones built in the laboratory. In humans, centromeres are typically located on repetitive α-satellite DNA, and these sequences are the "major ingredient" in first-generation human artificial chromosomes (HACs). Repetitive centromeric sequences present a major challenge for the design of synthetic mammalian chromosomes because they are difficult to synthesize, assemble, and characterize.

Structure of the Human Core Centromeric Nucleosome Complex.

Centromeric nucleosomes are at the interface of the chromosome and the kinetochore that connects to spindle microtubules in mitosis. The core centromeric nucleosome complex (CCNC) harbors the histone H3 variant, CENP-A, and its binding proteins, CENP-C (through its central domain; CD) and CENP-N (through its N-terminal domain; NT). CENP-C can engage nucleosomes through two domains: the CD and the CENP-C motif (CM).

Chromosomes: Keeping Centromeric Chromatin Tidy through S Phase.

The centromere, the chromosomal locus where the kinetochore is assembled in mitosis, is defined epigenetically, and its location must be remembered with each cell cycle. Recent studies elucidate how centromere identity is faithfully maintained despite challenges imposed by DNA replication.

Expanded Satellite Repeats Amplify a Discrete CENP-A Nucleosome Assembly Site on Chromosomes that Drive in Female Meiosis.

Female meiosis provides an opportunity for selfish genetic elements to violate Mendel's law of segregation by increasing the chance of segregating to the egg [1]. Centromeres and other repetitive sequences can drive in meiosis by cheating the segregation process [2], but the underlying mechanisms are unknown. Here, we show that centromeres with more satellite repeats house more nucleosomes that confer centromere identity, containing the histone H3 variant CENP-A, and bias their segregation to the egg relative to centromeres with fewer repeats.

Centromeres are maintained by fastening CENP-A to DNA and directing an arginine anchor-dependent nucleosome transition.

Maintaining centromere identity relies upon the persistence of the epigenetic mark provided by the histone H3 variant, centromere protein A (CENP-A), but the molecular mechanisms that underlie its remarkable stability remain unclear. Here, we define the contributions of each of the three candidate CENP-A nucleosome-binding domains (two on CENP-C and one on CENP-N) to CENP-A stability using gene replacement and rapid protein degradation. Surprisingly, the most conserved domain, the CENP-C motif, is dispensable.

PARP-1 Activation Requires Local Unfolding of an Autoinhibitory Domain.

Poly(ADP-ribose) polymerase-1 (PARP-1) creates the posttranslational modification PAR from substrate NAD(+) to regulate multiple cellular processes. DNA breaks sharply elevate PARP-1 catalytic activity to mount a cell survival repair response, whereas persistent PARP-1 hyperactivation during severe genotoxic stress is associated with cell death. The mechanism for tight control of the robust catalytic potential of PARP-1 remains unclear.

Both tails and the centromere targeting domain of CENP-A are required for centromere establishment.

The centromere-defined by the presence of nucleosomes containing the histone H3 variant, CENP-A-is the chromosomal locus required for the accurate segregation of chromosomes during cell division. Although the sequence determinants of human CENP-A required to maintain a centromere were reported, those that are required for early steps in establishing a new centromere are unknown. In this paper, we used gain-of-function histone H3 chimeras containing various regions unique to CENP-A to investigate early events in centromere establishment.

Sites of glucose transporter-4 vesicle fusion with the plasma membrane correlate spatially with microtubules.

In adipocytes, vesicles containing glucose transporter-4 (GLUT4) redistribute from intracellular stores to the cell periphery in response to insulin stimulation. Vesicles then fuse with the plasma membrane, facilitating glucose transport into the cell. To gain insight into the details of microtubule involvement, we examined the spatial organization and dynamics of microtubules in relation to GLUT4 vesicle trafficking in living 3T3-L1 adipocytes using total internal reflection fluorescence (TIRF) microscopy.

Kinetics of the interaction of myo1c with phosphoinositides.

myo1c is a single-headed myosin that dynamically links membranes to the actin cytoskeleton. A putative pleckstrin homology domain has been identified in the myo1c tail that binds phosphoinositides and soluble inositol phosphates with high affinity. However, the kinetics of association and dissociation and the influence of phospholipid composition on the kinetics have not been determined.

Elimination of platelet factor 4 (PF4) from platelets reduces atherosclerosis in C57Bl/6 and apoE-/- mice.

Activated platelets, which release platelet factor 4 (PF4) are present in patients with atherosclerosis. To date, no direct in-vivo evidence exists for the involvement of PF4 in atherogenesis. In the current study, we tested the hypothesis that PF4 is atherogenic, and that genetic elimination of PF4 would protect mice from atherosclerosis.