P-GAP-43 is enriched in horizontal cell divisions throughout rat cortical development

Area of Science:

• Neuroscience
• Developmental Biology
• Cell Biology

Background:

• Asymmetric cell divisions are crucial for mammalian cortical neurogenesis.
• The molecular mechanisms governing spindle orientation and asymmetric cell division in the developing central nervous system remain unclear.
• Understanding these mechanisms is vital for comprehending brain development.

Purpose of the Study:

• To identify a molecular marker for horizontally dividing neural precursor cells in the developing mammalian telencephalon.
• To investigate the role of growth-associated protein 43 (GAP-43) phosphorylation in neural precursor cell division.
• To provide insights into the regulation of neurogenesis.

Main Methods:

• Utilized the 2G12 antibody, which targets phosphorylated serine of GAP-43.
• Performed immunostaining on developing rat telencephalon sections during neurogenesis (embryonic day 13-17) and at the onset of gliogenesis (E21).
• Analyzed the localization and frequency of 2G12 immunoreactivity in mitotic cells within the cerebral cortex, ganglionic eminence, and subventricular zone.

Main Results:

• The 2G12 antibody labeled postmitotic neurons and a subset of cells undergoing mitosis.
• High frequency of 2G12 immunoreactivity was observed in cells dividing parallel to the ventricular surface throughout neurogenesis.
• This pattern was consistent in both the cerebral cortex and ganglionic eminence, including the subventricular zone.
• 2G12 immunostaining diminished in mitotic cells at E21, coinciding with the onset of gliogenesis.

Conclusions:

• Phosphorylation of GAP-43 occurs during the neuronal commitment phase within M-phase.
• The 2G12 antibody represents the first identified molecular correlate for horizontally dividing precursors in mammalian neurogenesis.
• This finding offers a new tool to study the mechanisms of asymmetric cell division and neurogenesis.