Elp1 is required for development of visceral sensory peripheral and central circuitry

Abstract

Cardiovascular instability and a blunted respiratory drive in hypoxic conditions, are hallmark features of the genetic sensory and autonomic neuropathy, familial dysautonomia (FD). FD results from a mutation in the gene ELP1, whose encoded protein is a scaffolding subunit of the six subunit Elongator complex. In mice, we and others have shown that Elp1 is essential for the normal development of neural crest derived-dorsal root ganglia (DRG) sensory neurons. Whether Elp1 is also required for development of ectodermal placode-derived visceral sensory receptors which are required for normal baroreception and chemosensory responses, has not been investigated. Using mouse models for FD, our data indicate that in fact the entire circuitry underlying baroreception and chemoreception is impaired due to a requirement for Elp1 not only in the visceral sensory neuron ganglia, but also for normal peripheral target innervation, and in their CNS synaptic partners in the medulla. Thus Elp1 is required in both placode- and neural crest-derived sensory neurons and its reduction aborts the normal development of neuronal circuitry essential for autonomic homeostasis and interoception. Summary statementDue to faulty afferent sensory signaling, patients with Familial dysautonomia (FD) have a diminished sensory arm of the baroreflex which would normally modulate blood pressure, and they have a blunted response to hypoxia and hypercapnia (Norcliffe-Kaufmann et al. 2010). Using mouse models for FD, we reveal here the underlying pathology which may underlie these severely impaired homeostatic reflex pathways in FD.