AUTHOR=Hasegawa Sonoko , Hirabayashi Takahiro , Kondo Takahiko , Inoue Ken , Esumi Shigeyuki , Okayama Atsushi , Hamada Shun , Yagi Takeshi TITLE=Constitutively expressed Protocadherin-α regulates the coalescence and elimination of homotypic olfactory axons through its cytoplasmic region JOURNAL=Frontiers in Molecular Neuroscience VOLUME=Volume 5 - 2012 YEAR=2012 URL=https://www.frontiersin.org/journals/molecular-neuroscience/articles/10.3389/fnmol.2012.00097 DOI=10.3389/fnmol.2012.00097 ISSN=1662-5099 ABSTRACT=

Olfactory sensory neuron (OSN) axons coalesce into specific glomeruli in the olfactory bulb (OB) according to their odorant receptor (OR) expression. Several guidance molecules enhance the coalescence of homotypic OSN projections, in an OR-specific- and neural-activity-dependent manner. However, the mechanism by which homotypic OSN axons are organized into glomeruli is unsolved. We previously reported that the clustered protocadherin-α (Pcdh-α) family of diverse cadherin-related molecules plays roles in the coalescence and elimination of homotypic OSN axons throughout development. Here we showed that the elimination of small ectopic homotypic glomeruli required the constitutive expression of a Pcdh-α isoform and Pcdh-α's cytoplasmic region, but not OR specificity or neural activity. These results suggest that Pcdh-α proteins provide a cytoplasmic signal to regulate repulsive activity for homotypic OSN axons independently of OR expression and neural activity. The counterbalancing effect of Pcdh-α proteins for the axonal coalescence mechanisms mediated by other olfactory guidance molecules indicate a possible mechanism for the organization of homotypic OSN axons into glomeruli during development.