Identification of a Novel Subset of Embryonic V2 Neurons in the Developing Mouse Spinal Cord

YANINA L. PETRACCA, MICAELA SARTORETTI Y GUILLERMO LANUZA.

Santa Cruz, Chile

Congreso; V International Meeting of the LASDB; 2010

Latin American Society for Developmental Biology and the Society for Developmental Biology

IDENTIFICATION OF A NOVEL SUBSET OF EMBRYONIC V2 NEURONS INTHE DEVELOPING MOUSE SPINAL CORDYanina L. Petracca, Micaela Sartoretti and Guillermo Lanuza.Developmental Neurobiology Laboratory. Fundación Instituto Leloir. Buenos Aires, Argentina.ypetracca@leloir.org.arIn spite of the progress made in understanding early events in cell specification, the mechanismsleading to the diversity of neuronal types in the central nervous system remain to be elucidated.In order to analyze how embryonic populations contribute to distinct cell types of the ventral spinal cord, we performed cell lineage tracing in Gata3Cre and Gata2GFP mice. We identified a novel population of Gata2/3+ cells that settles surrounding the central canal of the spinal cord, and that appear to be distinct to the previously characterized V2a/V2b interneurons. These cells, termed cerebrospinal fluid-contacting neurons (CCNs), have a unique morphology, with a dendritic-like process through the ependyma into the central canal and an axonal-like process extending towards ventral regions. CCNs expressing the ionic channel PKD2L1 are postmitotic cells that can be identified beginning at stage E14.5. Positional analysis of CCN generation with respect to dorso- ventral patterning genes (e.g. Nkx6.1, Pax6, Nkx2.2, Olig2) indicates that they are derived from p2 ventral progenitors. An additional confirmation that CCN are a subset of V2 neurons comes from the analysis of several mutant mouse lines in which CCNs develop normally in spite of that lack V0, V1 or V3 interneurons. In order to test whether CCNs are a novel population of “late-born” V2 cells, BrdU labeling experiments were performed. Our results indicate that CCNs progenitors actively divide until ~E14, contrasting to the earlier progenitor cell cycle exit that generates V2a (Chx10+) and V2b (Gata2/3+) interneurons. In addition our results indicate that different genetic mechanisms are involved in the genesis of distinct subsets of V2 cells. While the transcription factor Foxn4 is required in the control of early-born V2 neurons, our results showed that differentiation of CCNs is normal in Foxn4 mutant mice. These results suggest that restricted populations of precursors in the developing tube can sequentially differentiate into separate neuronal subtypes, contributing to the diversification of neuronal fates.Grant sponsors: MINCyT-ANPCyT Argentina (PICT07-1064), NIH-FIRCA (R03 TW008026) andIBRO Return Home Grant.