Integrins Have Cell-Type-Specific Roles in the Development of Motor Neuron Connectivity

Abstract

Formation of the nervous system requires a complex series of events including proper extension and guidance of neuronal axons and dendrites. Here we investigate the requirement for integrins, a class of transmembrane cell adhesion receptors, in regulating these processes across classes of <i>C. elegans</i> motor neurons. We show α integrin/<i>ina-1</i> is expressed by both GABAergic and cholinergic motor neurons. Despite this, our analysis of hypomorphic <i>ina-1(gm144)</i> mutants indicates preferential involvement of α integrin/<i>ina-1</i> in GABAergic commissural development, without obvious involvement in cholinergic commissural development. The defects in GABAergic commissures of <i>ina-1(gm144)</i> mutants included both premature termination and guidance errors and were reversed by expression of wild type <i>ina-1</i> under control of the native <i>ina-1</i> promoter. Our results also show that α integrin/<i>ina-1</i> is important for proper outgrowth and guidance of commissures from both embryonic and post-embryonic born GABAergic motor neurons, indicating an ongoing requirement for integrin through two phases of GABAergic neuron development. Our findings provide insights into neuron-specific roles for integrin that would not be predicted based solely upon expression analysis.