Reviews & Analysis

For nucleosome-encoded epigenetic information to be transmitted, an epigenetic mark requires a 'reader' for its physical recognition. CENP-N has now been identified as a reader of the centromere-specifying epigenetic mark that is generated by incorporation of the histone H3 variant CENP-A into centromeric nucleosomes.

Local regulation of protein translation is essential for synaptic plasticity. MicroRNA-mediated alteration in expression of an enzyme that regulates the palmitoylation of a specific synaptic protein determines dendritic spine size.

Eighty years of microscopy have established a conventional view of nuclear organization: dark-staining heterochromatin at the nuclear periphery and light-staining euchromatin in the interior. This nuclear architecture is inverted in rod cells of nocturnal mammals, demonstrating a unique functional nuclear genome reorganization specifically adapted for light transmission.

Stem cells achieve the remarkable task of generating both identical copies of themselves and lineage-restricted daughter cells that ultimately undergo terminal differentiation. The differential regulation of ribosomal protein biosynthesis helps to generate these two outcomes in Drosophila melanogaster.

Correct timing of developmental events is crucial for generating a normal organism. During oogenesis in Drosophila melanogaster, migration of border cells occurs in a defined temporal window and requires Jak/Stat and steroid hormone signalling. The initiation of border-cell migration is now shown to be timed by Jak/Stat-mediated downregulation of the BTB domain transcriptional regulator Abrupt, which acts as a negative regulator of steroid hormone signalling.

SCAI is a newly discovered protein that reduces cancer cell invasiveness. SCAI inhibits the MAL/SRF transcriptional activator complex that is downstream of Rho GTPase and actin, resulting in reduced expression of β₁-integrins and loss of invasive potential.

Focal adhesion turnover is essential for cell migration. New results show that the talin head liberated from talin by calpain II cleavage has a key role in these events, and that its levels are tightly regulated by Smurf1-mediated ubiquitylation counteracted by Cdk5-mediated phosphorylation.

The assembly of actin networks is dependent on nucleation-promoting factors. A new study identifies JMY as a protein containing two separate nucleation-promoting activities that shuttles between the nucleus and the cytoplasm and promotes cell migration. These observations indicate that JMY is an important factor controlling actin dynamics in motile cells.

To control cell proliferation, signal transduction needs to regulate the cell-cycle machinery. Recent findings show that Akt — a major kinase that coordinates diverse signalling pathways — phosphorylates Skp2, a subunit of the SCF-Skp2 ubiquitin ligase that targets key cell-cycle regulators. Akt1-dependent phosphorylation activates SCF-Skp2 through multiple mechanisms.

Depletion of Ca²⁺ from intracellular stores has long been known to signal to and activate plasma membrane 'store-operated' channels. We now learn that store depletion also controls the formation of cyclic AMP (cAMP) through the regulation of adenylyl cyclase (A-Cyclase). These findings substantially broaden the scope and biological significance of Ca²⁺ store-regulated signalling.

Ubiquitin E3 ligases of the RING and HECT families are distinct not only in their catalytic mechanisms but also in targeting substrates. Now it seems that one heterodimeric complex can target substrates to both types of E3 ligase.

Prions are abnormal isoforms of host proteins that are the infectious agents in certain mammalian neurodegenerative diseases. How prions travel from their peripheral entry sites to the brain where they cause disease is poorly understood. A new study finds that tunnelling nanotubes are important for the intercellular transfer of prions during neuroinvasion.

Frizzled receptors regulate cell fate decisions and planar cell polarity by means of distinct intracellular effectors. The choice between these two signalling outputs may involve a pH-dependent interaction between Dishevelled and negatively charged lipids at the plasma membrane.

Epigenetic mechanisms participate in the regulation of gene transcription in eukaryotes. Two studies in yeast have revealed an additional mechanism for controlling global gene transcription that is based on an inherited self-perpetuating change in the conformation of two different components of key transcriptional regulatory complexes.

Tumorigenesis is regulated by several mechanisms including signalling, transcription and DNA replication. Now a cytoplasmic protein quality-control pathway is implicated in the suppression of breast cancer cell growth, suggesting a new role for quality-control mechanisms in suppressing cells with malignant potential.