1. Early motor neuron pool identity and muscle nerve trajectory defined by postmitotic restrictions in Nkx6.1 activity.
- Author
-
De Marco Garcia NV and Jessell TM
- Subjects
- Age Factors, Animals, Chick Embryo, Embryo, Mammalian, Green Fluorescent Proteins metabolism, Hindlimb embryology, Hindlimb innervation, Homeodomain Proteins genetics, Horseradish Peroxidase metabolism, Mice, Mice, Transgenic, Models, Biological, Muscle Denervation methods, Muscle, Skeletal embryology, Mutation, Nerve Tissue Proteins metabolism, Spinal Cord embryology, Body Patterning physiology, Gene Expression Regulation, Developmental physiology, Homeodomain Proteins metabolism, Motor Neurons physiology, Muscle, Skeletal innervation, Spinal Cord cytology
- Abstract
The fidelity with which spinal motor neurons innervate their limb target muscles helps to coordinate motor behavior, but the mechanisms that determine precise patterns of nerve-muscle connectivity remain obscure. We show that Nkx6 proteins, a set of Hox-regulated homeodomain transcription factors, are expressed by motor pools soon after motor neurons leave the cell cycle, before the formation of muscle nerve side branches in the limb. Using mouse genetics, we show that the status of Nkx6.1 expression in certain motor neuron pools regulates muscle nerve formation, and the pattern of innervation of individual muscles. Our findings provide genetic evidence that neurons within motor pools possess an early transcriptional identity that controls target muscle specificity.
- Published
- 2008
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