RT Journal Article
SR Electronic
T1 Combinatorial effects of Alpha- and Gamma-Protocadherins on neuronal survival and dendritic self-avoidance.
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 3035-17
DO 10.1523/JNEUROSCI.3035-17.2018
A1 Samantha Ing-Esteves
A1 Dimitar Kostadinov
A1 Julie Marocha
A1 Anson D. Sing
A1 Kezia S. Joseph
A1 Mallory Laboulaye
A1 Joshua R. Sanes^
A1 Julie L. Lefebvre^
YR 2018
UL http://www.jneurosci.org/content/early/2018/02/08/JNEUROSCI.3035-17.2018.abstract
AB The clustered Protocadherins (Pcdhs) comprise 58 cadherin-related proteins encoded by three tandemly-arrayed gene clusters, Pcdh-alpha, -beta, and --gamma (Pcdha, Pcdhb, Pcdhg). Pcdh isoforms from different clusters are combinatorially expressed in neurons. They form multimers that interact homophilically, and mediate a variety of developmental processes, including neuronal survival, synaptic maintenance, axonal tiling and dendritic self-avoidance. Most studies have analyzed clusters individually. Here, we assess functional interactions between Pcdha and Pcdhg clusters. To circumvent neonatal lethality associated with deletion of Pcdhgs, we used Crispr-Cas9 genome editing in mice to combine a constitutive Pcdha mutant allele with a conditional Pcdhg allele. We analyzed roles of Pcdhas and Pcdhgs in the retina and cerebellum from mice (both sexes) lacking one or both clusters. In retina, Pcdhgs are essential for survival of inner retinal neurons and dendrite self-avoidance of starburst amacrine cells, while Pcdhas are dispensable for both processes. Deletion of both Pcdha and Pcdhg clusters led to far more dramatic defects in survival and self-avoidance than Pcdhg deletion alone. Comparisons of an allelic series of mutants support the conclusion that Pcdhas and Pcdhgs function together in a dose-dependent and cell-type specific manner to provide a critical threshold of Pcdh activity. In the cerebellum, Pcdhas and Pcdhgs also act synergistically to mediate self-avoidance of Purkinje cell dendrites, with modest but significant defects in either single mutant and dramatic defects in the double mutant. Together, our results demonstrate complex patterns of redundancy between Pcdh clusters and the importance of Pcdh cluster diversity in postnatal CNS development.SIGNIFICANCE STATEMENTThe formation of neural circuits requires diversification and combinatorial actions of cell surface proteins. Prominent among them are the clustered Protocadherins (Pcdhs), a family of ∼60 neuronal recognition molecules. Pcdhs are encoded by three closely-linked gene clusters called Pcdh-alpha, -beta and -gamma. The Pcdhs mediate a variety of developmental processes including neuronal survival, synaptic maintenance, and spatial patterning of axons and dendrites. Most studies to date have been limited to single clusters. Here we use genome editing to assess interactions between Pcdh-alpha and -gamma gene clusters. We examine two regions of the central nervous system, the retina and cerebellum, and show that the 14 alpha- and 22 gamma-Pcdhs act synergistically to mediate neuronal survival and dendrite patterning.