CTCF and cohesin help neurons raise their self-awareness

摘要

In the brain neurons form extensively intermingled projections and synap-tic interactions between them. To achieve proper neural connectivity, interactions between sections belonging to the same neuron are avoided. However, how can a cell tell, when it encounters another neuronal projection, whether it is part of the same cell? In other words, how do neurons become self-aware? Work of the last several years has revealed a complex system of self-recognition that involves expression of variable and cell-specific sets of cell-surface proteins (1). These sets constitute unique "barcodes" for each neuron and serve as molecular readouts of cell identity so that cells can distinguish between "self and "non-self." In PNAS, Monahan et al. (2) present data that provide insights into the molecular process by which otherwise identical cells can express unique "barcodes" of membrane proteins. Their results point to a role of large-scale chromatin architecture in setting and maintaining stochastic and cell-specific expression patterns of cell-surface proteins.