Volume 10 Issue 2, February 2009

Genetic studies combined within vivoimaging analysis have identified signalling pathways and developmentally regulated transcription factors that govern cell lineage allocation and axis patterning in the early mammalian embryo. These mechanisms are also conserved in lower vertebrates.

The 26S proteasome is a large protein complex that consists of a catalytic 20S core and a 19S regulatory particle, each of which contains numerous subunits. Proteasome-dedicated chaperones guarantee the efficient and correct assembly of this degradation machine, which is essential for its function.

MicroRNAs (miRNAs) are non-coding RNAs that bind to the 3′ untranslated region of target mRNAs to repress their translation and stability. Recently, miRNAs have been shown to regulate stem cell fate and behaviour by fine-tuning the protein levels of factors that are required for their function.

Recent progress in high-throughput sequencing has uncovered an astounding landscape of small RNAs in eukaryotic cells. Various small RNAs can be classified into three classes based on their biogenesis mechanism and the type of Argonaute protein that they are associated with.

General principles that govern how microRNAs select their targets and determine their mode of action are being challenged by recent findings in plant and animal systems. A common shortcoming of studies to date has been to address these questions under truein vivoconditions.

Although most eukaryotic proteins are secreted through the conventional endoplasmic reticulum–Golgi secretory pathway, both cytoplasmic and nuclear proteins have been shown to reach the cell surface by non-conventional transport pathways. The mechanisms and molecular components of unconventional protein secretion are beginning to emerge.