BSCB-BSDB Spring meeting
April 27 – 30, 2011
Since I very much enjoyed last year’s joint conference of the British Societies for Developmental Biology (BSDB) and Cell Biology (BSCB) in Warwick, I was optimistic about attending the 2011 meeting in Canterbury. The organisers unknowingly scheduled it for the days around the royal wedding – apparently a royal wedding can be organised faster than a scientific conference; nevertheless it was rather well attended. This year’s programme differed drastically from 2010, with a number of more descriptive approaches, frequently involving live imaging and mathematical modelling. I will focus my meeting report on the part organised by the BSDB and will highlight talks which I found particularly interesting. I’ve grouped them in a way that seems logical to me, which does not necessarily correspond to their distribution into the meeting’s sessions. In this first part I’ll just summarise Mark Krasnow’s fascinating plenary lecture.
Mark Krasnow (Stanford University, USA) opened the conference by explaining the branching process of the mouse bronchial tree during lung development. His team found that despite the tree’s ultimate complexity, branching is highly stereotyped between individuals. With this knowledge, they reconstructed the sequence of branching events from hundreds of carefully staged fixed specimens, and thereby built an enormous lineage diagram of the ~5,000 branches of the bronchial tree. It turns out to be the result of merely three distinct geometrical modes of branching, which are deployed in three different sequences at characteristic times and positions in the developing lung.
Krasnow then went on to demonstrate the power of clonal analysis for identifying the origins of some of the dozens of different cell types developing simultaneously in the lung. They pinned down the progenitor niche for airway smooth muscle, which surprisingly is located at the budding – and therefore moving – tip of the airway branch. Moreover, they identified the plexus, a blood-containing net of tubular endothelial cells surrounding the airways as the progenitor cells for the lung’s pulmonary veins and arteries. Finally, they found that of the two types of alveolar cells (AT1 and AT2), AT2 cells can de-differentiate and serve as progenitors for AT1 cells. Even more intriguingly, this result has given them insight into the early events in adenocarcinoma, which is the major lethal form of lung cancer: Expression of oncogenic (activated) K-Ras in mouse AT2 cells leads to lung cancer, whereas this is very rarely the case upon random expression of activated K-Ras in the lung. This strongly suggests that AT2 alveolar cells might be the cell type of origin of lung cancers, contrary to common belief that bronchiolar cells are to be blamed.
The talk left me fascinated by the beauty of the developing lung and also astonished by how much there still is to be discovered in developmental biology – be it by simply tracking cells as organs develop, or by tracing the origins of cell types using methods that have been around for a long time, such as clonal analysis. The rest of the conference presented more examples of this kind, do come back here for more!
Metzger RJ, Klein OD, Martin GR, & Krasnow MA (2008). The branching programme of mouse lung development. Nature, 453 (7196), 745-50 PMID: 18463632