A discrete Connexin26+ neural crest lineage emerges in mid-life and mediates enhanced central brainstem responses to elevated CO2 levels for deep breathing.

Researchers uncover a unique neural crest lineage of Cx26+ cells that emerges in middle age and plays a crucial role in regulating central brainstem responses to elevated CO2 levels for deep breathing. This discovery sheds light on the significant impact of a few cells on global metabolism and evolution.

Increased CO2 levels in blood and brain tissue stimulate lung ventilation, with CO2 directly binding to connexin26 (Cx26) hemichannels, causing them to open and release ATP. The new study reveals the existence of a discrete Cx26+ neural crest cell lineage that populates the ventral brainstem near the PreBoetz nucleus and CO2 chemosensory area during middle age. These approximately 20 cells die off in old age.

By specifically ablating Cx26 in this population of cells using two independent neural crest Cre-driver lines, researchers observed a 40% reduction in elevated tidal volume responses in middle age. This effect is directly linked to the arrival and wiring of this cell population in middle age, as well as its subsequent death in old age.

These findings represent the first known example of a middle-age change in cranial neural crest lineage composition and emphasize the substantial influence of a small number of cells on overall physiology.

The study also highlights the evolutionary significance of this lineage-dependent middle-age dynamic, particularly in the context of eusociality. In ancient amniote/synapsid ancestors, these middle-aged cells enabled small, naked pups to sense elevated CO2 levels in hypercapnic burrows, providing a crucial survival mechanism during extinction events such as the Permo-Triassic period.