Single-Molecule Real-Time Visualization of DNA Unwinding by CMG Helicase.

Faithful genome duplication is essential for preserving the genetic stability of dividing cells. DNA replication is carried out during the S phase by a dynamic complex of proteins termed the replisome. At the heart of the replisome is the CDC45-MCM2-7-GINS (CMG) helicase, which separates the two strands of the DNA double helix such that DNA polymerases can copy each strand.

Sister chromatid cohesion establishment during DNA replication termination.

Newly copied sister chromatids are tethered together by the cohesin complex, but how sister chromatid cohesion coordinates with DNA replication is poorly understood. Prevailing models suggest that cohesin complexes, bound to DNA before replication, remain behind the advancing replication fork to keep sister chromatids together. By visualizing single replication forks colliding with preloaded cohesin complexes, we find that the replisome instead pushes cohesin to where a converging replisome is met.

Duplex DNA engagement and RPA oppositely regulate the DNA-unwinding rate of CMG helicase.

A ring-shaped helicase unwinds DNA during chromosome replication in all organisms. Replicative helicases generally unwind duplex DNA an order of magnitude slower compared to their in vivo replication fork rates. However, the origin of slow DNA unwinding rates by replicative helicases and the mechanism by which other replication components increase helicase speed are unclear.

Smooth muscle-endothelial cell communication activates Reelin signaling and regulates lymphatic vessel formation.

Active lymph transport relies on smooth muscle cell (SMC) contractions around collecting lymphatic vessels, yet regulation of lymphatic vessel wall assembly and lymphatic pumping are poorly understood. Here, we identify Reelin, an extracellular matrix glycoprotein previously implicated in central nervous system development, as an important regulator of lymphatic vascular development. Reelin-deficient mice showed abnormal collecting lymphatic vessels, characterized by a reduced number of SMCs, abnormal expression of lymphatic capillary marker lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1), and impaired function.

Integrin-alpha9 is required for fibronectin matrix assembly during lymphatic valve morphogenesis.

Dysfunction of lymphatic valves underlies human lymphedema, yet the process of valve morphogenesis is poorly understood. Here, we show that during embryogenesis, lymphatic valve leaflet formation is initiated by upregulation of integrin-alpha9 expression and deposition of its ligand fibronectin-EIIIA (FN-EIIIA) in the extracellular matrix. Endothelial cell-specific deletion of Itga9 (encoding integrin-alpha9) in mouse embryos results in the development of rudimentary valve leaflets characterized by disorganized FN matrix, short cusps, and retrograde lymphatic flow.

Fluticasone, but not salmeterol, reduces cigarette smoke-induced production of interleukin-8 in human airway smooth muscle.

Cigarette smoke is the leading risk factor for the development of chronic obstructive pulmonary disease. We have recently shown that cigarette smoke extract synergises with tumour necrosis factor alpha (TNFalpha) in the induction of interleukin-8 (IL-8) from human airway smooth muscle cells. We have investigated the effect of fluticasone propionate, a corticosteroid, and salmeterol, a beta 2-adrenergic receptor agonist, on cigarette smoke extract-induced IL-8 production by human airway smooth muscle cells.

p38 MAP kinase inhibitor reverses stress-induced cardiac myocyte dysfunction.

Stress is gaining increasing acceptance as an independent risk factor contributing to adverse cardiovascular outcomes. Potential mechanisms responsible for the deleterious effects of stress on the development and progression of cardiovascular disease remain to be elucidated. An established animal model of stress in humans is the prenatally stressed (PS) rat.