Short- and long-range roles of UNC-6/Netrin in dorsal-ventral axon guidance in vivo in Caenorhabditis elegans.

Recent studies in vertebrates and Caenorhabditis elegans have reshaped models of how the axon guidance cue UNC-6/Netrin functions in dorsal-ventral axon guidance, which was traditionally thought to form a ventral-to-dorsal concentration gradient that was actively sensed by growing axons. In the vertebrate spinal cord, floorplate Netrin1 was shown to be largely dispensable for ventral commissural growth. Rather, short range interactions with Netrin1 on the ventricular zone radial glial stem cells was shown to guide ventral commissural axon growth.

The DPY-14 cuticle collagen regulates left-right asymmetric neuronal migration in .

Nervous systems of bilaterally-symmetric animals display left-right asymmetries in development. In , the Q neuroblasts display left-right asymmetry of migration, with QR on the right migrating anteriorly and QL on the left migrating posteriorly. Previous worked showed that a group of transmembrane receptor molecules including UNC-40 /DCC and PTP-3 /LAR control direction of initial Q migration.

SRC-1 controls growth cone polarity and protrusion with the UNC-6/Netrin receptor UNC-5 in Caenorhabditis elegans.

The Polarity/Protusion model of UNC-6/Netrin function in axon repulsion does not rely on a gradient of UNC-6/Netrin. Instead, the UNC-5 receptor polarizes the VD growth cone such that filopodial protrusions are biased to the dorsal leading edge. UNC-5 then inhibits growth cone protrusion ventrally based upon this polarity, resulting in dorsally-biased protrusion and dorsal migration away from UNC-6/Netrin.

Short- and long-range roles of UNC-6/Netrin in dorsal-ventral axon guidance in .

Recent studies in vertebrates and have reshaped models of how the axon guidance cue UNC-6/Netrin functions in dorsal-ventral axon guidance, which was traditionally thought to form a ventral-to-dorsal concentration gradient that was actively sensed by growing axons. In the vertebrate spinal cord, floorplate Netrin1 was shown to be largely dispensable for ventral commissural growth. Rather, short range interactions with Netrin1 on the ventricular zone radial glial stem cells was shown to guide ventral commissural axon growth.

MAB-5/Hox regulates the Q neuroblast transcriptome, including cwn-1/Wnt, to mediate posterior migration in Caenorhabditis elegans.

Neurogenesis involves the precisely coordinated action of genetic programs controlling large-scale neuronal fate specification down to terminal events of neuronal differentiation. The Q neuroblasts in Caenorhabditis elegans, QL on the left and QR on the right, divide, differentiate, and migrate in a similar pattern to produce three neurons each. However, QL on the left migrates posteriorly, and QR on the right migrates anteriorly.