NCAM expression induces neurogenesis in vivo

Area of Science:

• Neuroscience
• Cell Biology
• Developmental Biology

Background:

• Neural cell adhesion molecule (NCAM) is crucial for neural development and adult brain function.
• Most NCAM functions are attributed to its polysialic acid (PSA) modification.
• Previous studies indicated NCAM expression interferes with forebrain neuronal stem cell maintenance.

Purpose of the Study:

• Investigate the fate of cells derived from NCAM-overexpressing stem cells in the postnatal mouse brain.
• Identify the specific functional domains of NCAM responsible for its effects on neurogenesis.
• Determine if the neurogenic effect is dependent on PSA modification.

Main Methods:

• Utilized transgenic mouse models with ectopic expression of NCAM140 isoform in radial glia and type C cells.
• Analyzed cell proliferation and neuronal differentiation in the rostral migratory stream.
• Generated and tested mutant NCAM proteins lacking specific domains.

Main Results:

• Ectopic NCAM140 expression increased cell proliferation and the generation of neuronal type A cells in the rostral migratory stream.
• A mutant NCAM protein containing only fibronectin type III repeats and immunoglobulin-like domain 5 was sufficient to induce this effect.
• The observed neurogenic effect was independent of PSA, as transgenic NCAM lacked PSA modification in the studied cells.

Conclusions:

• NCAM can promote neurogenesis in the postnatal brain by influencing stem cell proliferation.
• Specific domains of NCAM, independent of PSA, mediate this neurogenic effect.
• Heterophilic interactions of NCAM with other cell membrane components are likely involved in mediating its function.