Heterozygous variant as a novel genetic cause of telomere biology disorders.

Premature telomere shortening or telomere instability is associated with a group of rare and heterogeneous diseases collectively known as telomere biology disorders (TBDs). Here we identified two unrelated individuals with clinical manifestations of TBDs and short telomeres associated with the identical monoallelic variant c.767A>G; Y256C in Although the replication protein A2 (RPA2) mutant did not affect ssDNA binding and G-quadruplex-unfolding properties of RPA, the mutation reduced the affinity of RPA2 with the ubiquitin ligase RFWD3 and reduced RPA ubiquitination.

mTert induction in p21-positive cells counteracts capillary rarefaction and pulmonary emphysema.

Lung diseases develop when telomeres shorten beyond a critical point. We constructed a mouse model in which the catalytic subunit of telomerase (mTert), or its catalytically inactive form (mTert), is expressed from the p21 locus. Expression of either TERT or TERT reduces global p21 levels in the lungs of aged mice, highlighting TERT non-canonical function.

Rad52 SUMOylation functions as a molecular switch that determines a balance between the Rad51- and Rad59-dependent survivors.

Functional telomeres in yeast lacking telomerase can be restored by rare Rad51- or Rad59-dependent recombination events that lead to type I and type II survivors, respectively. We previously proposed that polySUMOylation of proteins and the SUMO-targeted ubiquitin ligase Slx5-Slx8 are key factors in type II recombination. Here, we show that SUMOylation of Rad52 favors the formation of type I survivors.

High levels of histones promote whole-genome-duplications and trigger a Swe1-dependent phosphorylation of Cdc28.

Whole-genome duplications (WGDs) have played a central role in the evolution of genomes and constitute an important source of genome instability in cancer. Here, we show in that abnormal accumulations of histones are sufficient to induce WGDs. Our results link these WGDs to a reduced incorporation of the histone variant H2A.

Binding to RNA regulates Set1 function.

The Set1 family of histone H3 lysine 4 (H3K4) methyltransferases is highly conserved from yeast to human. Here we show that the Set1 complex (Set1C) directly binds RNA through the regions that comprise the double RNA recognition motifs (dRRM) and N-SET domain within Set1 and its subunit Spp1. To investigate the functional relevance of RNA binding, we performed UV RNA crosslinking (CRAC) for Set1 and RNA polymerase II in parallel with ChIP-seq experiments.

Histone Purification from Saccharomyces cerevisiae.

The nucleosome structure consists of a histone octamer made by a tetramer of H3-H4 histones and two dimers of H2A-H2B. Nucleosomes undergo extensive posttranslational modifications that regulate nucleosome interactions, position, and stability.We describe a protocol allowing the robust purification of histones from the yeast Saccharomyces cerevisiae.

Posttranslational marks control architectural and functional plasticity of the nuclear pore complex basket.

The nuclear pore complex (NPC) serves as both the unique gate between the nucleus and the cytoplasm and a major platform that coordinates nucleocytoplasmic exchanges, gene expression, and genome integrity. To understand how the NPC integrates these functional constraints, we dissected here the posttranslational modifications of the nuclear basket protein Nup60 and analyzed how they intervene to control the plasticity of the NPC. Combined approaches highlight the role of monoubiquitylation in regulating the association dynamics of Nup60 and its partner, Nup2, with the NPC through an interaction with Nup84, a component of the Y complex.

Genome-wide RNA polymerase II: not genes only!

RNA polymerase (Pol) II transcriptional regulation is an essential process for guiding eukaryotic gene expression. Early in vitro studies deciphered the essential steps for transcription, including recruitment, initiation, elongation and termination. Based on these findings, the idea emerged that Pol II should essentially be located on promoters or genic regions of transcribed genes.

Dynamics of thymus-colonizing cells during human development.

Here, we identify fetal bone marrow (BM)-derived CD34hiCD45RAhiCD7+ hematopoietic progenitors as thymus-colonizing cells. This population, virtually absent from the fetal liver (FL), emerges in the BM by development weeks 8-9, where it accumulates throughout the second trimester, to finally decline around birth. Based on phenotypic, molecular, and functional criteria, we demonstrate that CD34hiCD45RAhiCD7+ cells represent the direct precursors of the most immature CD34hiCD1a- fetal thymocytes that follow a similar dynamics pattern during fetal and early postnatal development.

CD40 ligation and phagocytosis differently affect the differentiation of monocytes into dendritic cells.

That monocytes can differentiate into macrophages or dendritic cells (DCs) makes them an essential link between innate and adaptive immunity. However, little is known about how interactions with pathogens or T cells influence monocyte engagement toward DCs. We approached this point in cultures where granulocyte macrophage-colony stimulating factor (GM-CSF) and interleukin (IL)-4 induced monocytes to differentiate into immature DCs.