Articles in 2007

The Ringberg Colloquia were launched last month with a meeting entitled “Self-organization and Morphogenesis in Biological Systems”. The series promises to provide a discussion-oriented forum for interdisciplinary research.

The microtubule associated protein tau is involved in the neuropathology of Alzheimer's disease, however, the mechanistic basis for the involvement of tau is unclear. New evidence indicates that tau may mediate neurotoxicity by altering the organization and dynamics of the actin cytoskeleton.

The transcription factor GATA-3 is necessary for the formation of a mammary gland and the maintenance of mammary-cell differentiation. The loss of GATA-3 function in a fully formed mammary gland generates oestrogen receptor-negative, proliferating cells that lack expression of myoepithelial markers. Cells with similar characteristics in breast cancer are associated with poor prognosis.

In proliferating cells, the SCF^Skp2ubiquitin ligase targets the CDK inhibitor p27 for proteolysis. A study now shows that the tumour suppressor pRb promotes the APC/C^Cdh1–mediated degradation of Skp2, resulting in the accumulation of p27.

The Ringberg Colloquium on Self-Organization and Morphogenesis in Biological Systems took place between December 3–6, 2006 in a castle near Munich, Germany. Researchers from different areas of cell and developmental biology exchanged ideas about how biological systems are organized and dynamic at the same time. A dominant theme was that local interactions between molecules or cells can generate global order.

New studies reveal the dynamic accumulation of phosphatidylinositol (3,4,5) trisphosphate (PtdIns(3,4,5)P₃) at the leading edge of primary neutrophils during chemotaxis. They also demonstrate that SHIP1, rather than phosphatase and tensin homologue (PTEN), is responsible for the degradation and localization of this lipid in neutrophils and shed light on the role of PtdIns(3,4,5)P₃ in directional sensing.

Bone morphogenetic proteins (BMPs) shape vertebrate limbs and define digits by inducing programmed cell death in interdigital tissues. Recent findings show that Drosophila legs are also sculpted by programmed cell death. In this case, rather than the absolute activity of BMP, it is the sharp discontinuity of BMP signalling that is required for forming the leg joint.

In eukaryotes, condensing chromosomal DNA into heterochromatin is important for gene silencing and proper chromosome segregation. A recent study suggests a function for heterochromatin in protecting highly repeated genes and satellite DNA against excision caused by recombination or by joining of free DNA ends following DNA damage.

In a recent trial Nature explored ways to improve the peer review system.

Each round of DNA replication results in the erosion of telomeres, the ends of linear chromosomes. Telomerase counteracts telomere shortening by synthesizing new DNA sequences in a time period restricted to late S a d G2 cell-cycle phases, even though the enzyme is active throughout the cell cycle. A recent study directly implicates cyclin dependent kinase (Cdk1) in the regulation of telomere elongation during the cell cycle.

The nucleosome surface is decorated with an array of enzyme-catalysed modifications on histone tails. These modifications have well-defined roles in a variety of ongoing chromatin functions, often by acting as receptors for non-histone proteins, but their longer-term effects are less clear. Here, an attempt is made to define how histone modifications operate as part of a predictive and heritable epigenetic code that specifies patterns of gene expression through differentiation and development.