Characterization of Foxp2-expressing cells in the developing spinal cord

Area of Science:

• Neuroscience
• Developmental Biology
• Genetics

Background:

• Winged-helix/forkhead transcription factors, Foxp1 and Foxp2, are crucial in the central nervous system (CNS).
• Foxp1 is known to be expressed in V1 interneurons and motor neurons during mouse embryogenesis.
• The expression pattern and relationship of Foxp2 with Foxp1 in the developing spinal cord are not fully understood.

Purpose of the Study:

• To characterize the expression pattern of Foxp2 during mouse embryogenesis.
• To elucidate the relationship between Foxp1 and Foxp2 expression in the developing spinal cord.
• To investigate the potential roles of Foxp1 and Foxp2 in spinal cord development.

Main Methods:

• Characterization of Foxp2-expressing cells during mouse embryogenesis using immunohistochemistry.
• Double-immunofluorescence staining for Foxp2 with transcription factors (Pax2, En1, Evx1, Chx10, Gata3, Lhx3) and cell markers (beta-tubulin, calbindin).
• Analysis of co-localization of Foxp1 and Foxp2 in ventral spinal cord interneurons.

Main Results:

• Foxp2-expressing cells were identified as postmitotic neurons in the ventral spinal cord starting at embryonic day 11.0.
• Between E13.5 and E15.5, Foxp2 was highly expressed in medial and lateral ventral spinal cord.
• Foxp2-expressing neurons were characterized as V1 interneurons (Pax2+, En1+, Evx1-, Chx10-, Gata3-, Lhx3-) and did not colocalize with Foxp1, suggesting distinct expression subsets within V1 interneurons. Neither Foxp1 nor Foxp2 were found in calbindin+ Renshaw cells.

Conclusions:

• Foxp1 and Foxp2 are expressed in distinct subsets of V1 interneurons, specifically non-Renshaw cells, in the developing ventral spinal cord.
• These transcription factors likely play roles in determining cell type identities, including neurotransmitter classes and functional subtypes (e.g., Ia and Ib inhibitory interneurons) during late embryogenesis.