As a stem cell colony develops from a single progenitor, it forms a branching lineage tree in which each bifurcation corresponds to a cell division. Not all cells, however, continue to proliferate indefinitely: while some branches keep growing, others eventually stop as cells exit the cell cycle. Until now, it was unclear whether this occurred randomly or not. In a new work published in PRX Life, the authors introduce a novel Shannon-type measure, the inheritance entropy, able to quantify the flow of information underlying the tree. At some point in the lineage, an epigenetic mutation arises that increases the propensity of all descendant cells to stop dividing. The delay between this mutation and its phenotypic manifestation as cell-cycle exit reduces the entropy of the lineage tree, revealing an ordered hereditary structure that is fundamentally different from a purely random process.

andrea.cavagna@roma1.infn.it
irene.giardina@uniroma1.it
francescosaverio.rotondi@uniroma1.it