Genetic disruption of bassoon in two mutant mouse lines causes divergent retinal phenotypes

Bassoon (BSN) is a presynaptic cytomatrix protein ubiquitously present at chemical synapses of the central nervous system, where it regulates synaptic vesicle replenishment and organizes voltage-gated Ca2+ channels. In sensory photoreceptor synapses, BSN additionally plays decisive role in anchoring ribbon, organelle functional extension active zone, to membrane. this study, we functionally structurally analyzed two mutant mouse lines with genetic disruption Bsn—Bsngt Bsnko—using electrophysiology high-resolution microscopy. both Bsn lines, full-length was abolished, function similarly impaired, yet synapse structure more severely affected Bsngt/gt than Bsnko/ko photoreceptors. The defects retina coincide remodeling outer retina—rod bipolar horizontal cell sprouting, formation ectopic ribbon sites—and death cone photoreceptors, processes that did not occur retina. An analysis Bsngt/ko hybrid mice revealed divergent retinal phenotypes can be attributed expression Bsngt allele, which triggers neurite sprouting These findings shed new light on existing models might help understand mechanisms drive death.