PCP and Septins govern the polarized organization of the actin cytoskeleton during convergent extension.

Convergent extension (CE) requires the coordinated action of the planar cell polarity (PCP) proteins and the actin cytoskeleton, but this relationship remains incompletely understood. For example, PCP signaling orients actomyosin contractions, yet actomyosin is also required for the polarized localization of PCP proteins. Moreover, the actin-regulating Septins play key roles in actin organization and are implicated in PCP and CE in frogs, mice, and fish but execute only a subset of PCP-dependent cell behaviors.

New tools reveal PCP-dependent polarized mechanics in the cortex and cytoplasm of single cells during convergent extension.

Unlabelled: Understanding biomechanics of biological systems is crucial for unraveling complex processes like tissue morphogenesis. However, current methods for studying cellular mechanics are limited by the need for specialized equipment and often provide limited spatiotemporal resolution. Here we introduce two new techniques, Tension by Transverse Fluctuation (TFlux) and microrheology, that overcome these limitations.

Twinfilin1 controls lamellipodial protrusive activity and actin turnover during vertebrate gastrulation.

The dynamic control of the actin cytoskeleton is a key aspect of essentially all animal cell movements. Experiments in single migrating cells and in vitro systems have provided an exceptionally deep understanding of actin dynamics. However, we still know relatively little of how these systems are tuned in cell-type-specific ways, for example in the context of collective cell movements that sculpt the early embryo.

Functional partitioning of a liquid-like organelle during assembly of axonemal dyneins.

Ciliary motility is driven by axonemal dyneins that are assembled in the cytoplasm before deployment to cilia. Motile ciliopathy can result from defects in the dyneins themselves or from defects in factors required for their cytoplasmic pre-assembly. Recent work demonstrates that axonemal dyneins, their specific assembly factors, and broadly-acting chaperones are concentrated in liquid-like organelles in the cytoplasm called DynAPs (Dynein Axonemal Particles).

A systematic, label-free method for identifying RNA-associated proteins in vivo provides insights into vertebrate ciliary beating machinery.

Cell-type specific RNA-associated proteins are essential for development and homeostasis in animals. Despite a massive recent effort to systematically identify RNA-associated proteins, we currently have few comprehensive rosters of cell-type specific RNA-associated proteins in vertebrate tissues. Here, we demonstrate the feasibility of determining the RNA-associated proteome of a defined vertebrate embryonic tissue using DIF-FRAC, a systematic and universal (i.

Testis-specific Arf promoter expression in a transposase-aided BAC transgenic mouse model.

CDKN2A is an evolutionarily conserved gene encoding proteins implicated in tumor suppression, ocular development, aging, and metabolic diseases. Like the human form, mouse Cdkn2a encodes two distinct proteins-p16, which blocks cyclin-dependent kinase activity, and p19, which is best known as a positive regulator of the p53 tumor suppressor-and their functions have been well-studied in genetically engineered mouse models. Relatively little is known about how expression of the two transcripts is controlled in normal development and in certain disease states.

p19(Arf) limits primary vitreous cell proliferation driven by PDGF-B.

Arf encodes an important tumor suppressor, p19(Arf), which also plays a critical role to control hyperplasia in the primary vitreous during mouse eye development. In the absence of Arf, mice are born blind and display a phenotype closely mimicking severe forms of the human eye disease, persistent hyperplastic primary vitreous (PHPV). In this report, we characterize p19(Arf) expression in perivascular cells that normally populate the primary vitreous and express the Arf promoter.

Isolation and characterization of mammalian cells expressing the Arf promoter during eye development.

Although many researchers have successfully uncovered novel functions of the tumor suppressor p19(Arf) utilizing various types of cultured cancer cells and immortalized fibroblasts, these systems do not accurately reflect the endogenous environment in which Arf is developmentally expressed. We addressed this by isolating perivascular cells (PVCs) from the primary vitreous of the mouse eye. This rare cell type normally expresses the p19(Arf) tumor suppressor in a non-pathological, developmental context.