Abstract
VLGR1/ADGRV1 (very large G protein-coupled receptor-1) is the largest
known adhesion G protein-coupled receptor. Mutations in VLGR1/ADGRV1
cause Usher syndrome (USH), the most common form of hereditary
deaf-blindness, and have been additionally linked to epilepsy. Although
VLGR1/ADGRV1 is almost ubiquitously expressed, little is known about the
subcellular function and signalling of the VLGR1 protein and thus about
mechanisms underlying the development of diseases. Using affinity
proteomics, we have identified key components of autophagosomes as
putative interacting proteins of VLGR1. In addition, whole transcriptome
sequencing of the retinae of the Vlgr1/del7TM mouse model revealed
altered expression profiles of gene-related autophagy. Monitoring
autophagy by immunoblotting and immunocytochemistry of the LC3 and p62
as autophagy marker proteins revealed evoked autophagy in
VLGR1-deficient hTERT-RPE1 cells and USH2C patient-derived fibroblasts.
Our data demonstrate the molecular and functional interaction of VLGR1
with key components of the autophagy process and point to an essential
role of VLGR1 in the regulation of autophagy at internal membranes. The
close association of VLGR1 with autophagy helps to explain the
pathomechanisms underlying human USH and epilepsy-related to VLGR1
defects.