AUTHOR=Weghorst Forrest , Mirzakhanyan Yeva , Samimi Kian , Dhillon Mehron , Barzik Melanie , Cunningham Lisa L. , Gershon Paul D. , Cramer Karina S. 

TITLE=Caspase-3 Cleaves Extracellular Vesicle Proteins During Auditory Brainstem Development

JOURNAL=Frontiers in Cellular Neuroscience

VOLUME=Volume 14 - 2020

YEAR=2020

URL=https://www.frontiersin.org/journals/cellular-neuroscience/articles/10.3389/fncel.2020.573345

DOI=10.3389/fncel.2020.573345

ISSN=1662-5102

ABSTRACT=Sound localization requires extremely precise development of auditory brainstem circuits, the molecular mechanisms of which are largely unknown. We previously demonstrated a novel requirement for non-apoptotic activity of the protease caspase-3 in chick auditory brainstem development. Here, we used mass spectrometry to identify proteolytic substrates of caspase-3 during chick auditory brainstem development. Functional annotation analysis revealed that our caspase-3 substrates were enriched more than two-fold for proteins associated with extracellular vesicles (EVs), membrane-bound nanoparticles that function in intercellular communication. The proteome of EVs isolated from the auditory brainstem contained caspase-3 and was highly enriched for the caspase-3 substrates identified here. Additionally, we identified two caspase-3 substrates with known functions in axon guidance, namely Neural Cell Adhesion Molecule (NCAM) and Neuronal-glial Cell Adhesion Molecule (Ng-CAM), that were found in auditory brainstem EVs and expressed in the auditory pathway alongside cleaved caspase-3. Taken together, these data suggest a novel developmental mechanism whereby caspase-3 influences auditory brainstem circuit formation through the proteolytic cleavage of EV proteins.