GATA Proteins Identify a Novel Ventral Interneuron Subclass in the Developing Chick Spinal Cord

Abstract

Members of the GATA transcription factor gene family have been implicated in a variety of developmental processes, including that of the vertebrate central nervous system. However, the role of GATA proteins in spinal cord development remains unresolved. In this study, we investigated the expression and function of two GATA proteins, GATA2 and GATA3, in the developing chick spinal cord. We show that both proteins are expressed by a distinct subpopulation of ventral interneurons that share the same dorsoventral position as CHX10-positive V2 interneurons. However, no coexpression is observed between the two GATA proteins and CHX10. By in vivo notochord grafting and cyclopamine treatment, we demonstrate that the spatially restricted pattern of GATA3 expression is regulated, at least in part, by the signaling molecule Sonic hedgehog. In addition, we further show that Sonic hedgehog induces GATA3 expression in a dose-dependent manner. Using in ovo electroporations, we also demonstrate that GATA2 is upstream of GATA3 in the same epigenetic cascade and that GATA3 is capable of inducing GATA2 expression in vivo. Furthermore, the ectopically expressed GATA proteins can repress differentiation of other ventral cell fates, but not the development of progenitor populations identified by PAX protein expression. Taken together, our findings strongly suggest an important role for GATA2 and GATA3 proteins in the establishment of a distinct ventral interneuron subpopulation in the developing chick spinal cord.

Pax6andEngrailed 1Regulate Two Distinct Aspects of Renshaw Cell Development

“…It is unclear, however, at what developmental time these functionally distinct cell types emerge. Whereas V2 INs can be subdivided into two subtypes soon after they are born (Kuranaratne et al, 2002), postmitotic V1 INs appear to be genetically and morphologically homogeneous (Saueressig et al, 1999;M. Goulding, unpublished results), suggesting that V1 IN diversification may be a late event.…”

alx, a Zebrafish Homolog ofChx10, Marks Ipsilateral Descending Excitatory Interneurons That Participate in the Regulation of Spinal Locomotor Circuits

“…Chx10 in amniotes marks a subset of V2 neurons, called V2a neurons (Karunaratne et al, 2002). We have revealed that alx marks ipsilateral descending neurons that provide excitation to motoneurons during locomotion.…”

Regulatory pathways linking progenitor patterning, cell fates and neurogenesis in the ventral neural tube

“…In addition, mechanisms that increase the initial diversity of neuronal subtypes are also likely to operate. For example, the expression of additional transcription factors divides the V2 neuron population into two spatially intermixed groups of neurons that appear to be generated in the same region of the spinal cord (Karunaratne et al 2002;Smith et al 2002). Nevertheless, examining the generation of MNs and V0-V3 neurons serves as a powerful experimental paradigm for exploring the mechanisms that control the spatial allocation of neuronal subtype identity.…”