Lrig1 and Lrig3 cooperate to control Ret-mediated axonal growth sensory neurons and nonpeptidergic epidermis innervation

DE VINCENTI, ANA PAULA; ALSINA FC; FERRERO RESTELLI, FACUNDO; HEDMAN H; LEDDA F; PARATCHA G

DEVELOPMENT

COMPANY OF BIOLOGISTS LTD

Lugar: Cambridge; Año: 2021

0950-1991

Negative feedback-loop represents a regulatory mechanism that guarantees signaling thresholds compatible with a physiological response. Previously, we established that Lrig1, acts through this mechanism to inhibit Ret activity. However, it is unclear whether other Lrig-family members play similar roles. Here, we show that Lrig1 and Lrig3 are co-expressed in Ret-positive dorsal root ganglion (DRG) neurons. Lrig3, like Lrig1, interacts with Ret and inhibits GDNF/Ret signaling. Treatment of DRG neurons with GDNF ligands induces a significant increase in the expression of Lrig1 and Lrig3. Our findings show that whereas single deletion of either Lrig1 or Lrig3 fails to promote Ret-mediated axonal growth, haploinsufficiency of Lrig1 in Lrig3 mutants significantly potentiates Ret signaling and axonal growth of DRG neurons in response to GDNF ligands. We observe that Lrig1 and Lrig3 act redundantly to ensure proper cutaneous innervation of nonpeptidergic axons and behavioral sensitivity to cold, which correlate with a significant increase in the expression of the cold-responsive channel, TrpA1. Together our findings provide novel insights into the in vivo functions through which Lrig genes control morphology, connectivity and function in sensory neurons.