The suprachiasmatic nucleus (SCN) is the mammalian central circadian pacemaker, coordinating 24 h rhythms in physiology and behaviour. How its cellular architecture and functional properties are established and the contribution of maternal and environmental signals during development remain poorly understood. We have generated a snRNA-seq dataset spanning the fetal and postnatal SCN development to characterise cellular trajectories and identify pathways associated with the emergence of circadian rhythms.

Our hypothesis challenges the traditional neurocentric view on the gain of functionality of the SCN circuit exploring the role of glial cells. We have started by characterising the progenitor populations underlying SCN gliogenesis and their progression towards mature glial populations displaying transcriptional profiles essential for SCN function.

Moreover, we used our dataset to ask whether in this GABAergic circuit, the polarity switch happens during development. In the SCN circuit maturation seems to follow specific developmental rules, happening in a cell type- and region-specific way. Preliminary data suggest that manipulating GABA polarity in vivo impacts mainly the pacemaker properties in absence of light, providing an initial insight into developmental trajectories underlying the functional maturation of the clock. Together, these approaches contribute to answer a long standing question in the field: when (and how) the circadian clock starts to tick.

More information:

• Laboratory of Circadian Physiology of Neurons and Glia