Proximity-dependent proteomics reveals extensive interactions of Protocadherin-19 with regulators of Rho GTPases and the microtubule cytoskeleton

Abstract

Protocadherin-19 belongs to the cadherin family of cell surface receptors and has been shown to play essential roles in the development of the vertebrate nervous system. Mutations in human Protocadherin-19 (PCDH19) lead to PCDH19 Female-limited epilepsy (PCDH19 FLE) in humans, characterized by the early onset of epileptic seizures in children and a range of cognitive and behavioral problems in adults. Despite being considered the second most prevalent gene in epilepsy, very little is known about the intercellular pathways in which it participates. In order to characterize the protein complexes within which Pcdh19 functions, we generated Pcdh19-BioID fusion proteins and utilized proximity-dependent biotinylation to identify neighboring proteins. Proteomic identification and analysis revealed that the Pcdh19 interactome is enriched in proteins that regulate Rho family GTPases, microtubule binding proteins and proteins that regulate cell divisions. We cloned the centrosomal protein Nedd1 and the RacGEF Dock7 and verified their interactions with Pcdh19 in vitro. Our findings provide the first comprehensive insights into the interactome of Pcdh19, and provide a platform for future investigations into the cellular and molecular biology of this protein critical to the proper development of the nervous system.

Modifying PCDH19 levels affects cortical interneuron migration

“…It remains to be investigated whether PCDH19 fulfills the criteria of a dependence receptor; whether it can be cleaved by caspases and initiate apoptosis, or whether it acts indirectly by stabilizing a known dependence receptor at the membrane. Interesting is the finding that PCDH19 interacts with Protein Tyrosine Phosphatase Non-Receptor Type 13 (PTPN13), a protein that prevents apoptosis when bound to NGFR, a known dependence receptor (Emond et al, 2020 ). Stabilization of a dependence receptor also fits with the observation that a truncated PCDH19-ECD, which is unlikely to exert any cytoplasmic interactions, can trigger apoptosis upon overexpression as well.…”