Figure 8.

Potential roles for GDF7 in the regulation of interneuron fate in the dorsal spinal cord. The generation of late mATH1⁺ progenitors and D1A neurons depends on GDF7 activity. In contrast, other BMP signals from the epidermal ectoderm and/or roof plate appear to be sufficient for the induction of early mATH1⁺ progenitors and the differentiation of D1B neurons. GDF7 could function in the generation of D1A neurons in one of two ways: GDF7 may act on dorsal Pax3⁺, Pax7⁺ neural plate cells to induce the late population of mATH1⁺ progenitors that differentiate into D1A neurons (Model 1). Alternatively, GDF7 may be required to convert the early D1B-fated mATH1⁺ progenitors into the late class of mATH1⁺ progenitors that generates D1A neurons (Model 2).