Molyneaux BJ, Arlotta P, Fame RM, MacDonald JL, MacQuarrie KL, Macklis JD. 2009. Novel subtype-specific genes identify distinct subpopulations of callosal projection neurons. The Journal of neuroscience : the official journal of the Society for Neuroscience. 29(39):12343-54. Pubmed: 19793993 DOI:10.1523/JNEUROSCI.6108-08.2009


Little is known about the molecular development and heterogeneity of callosal projection neurons (CPN), cortical commissural neurons that connect homotopic regions of the two cerebral hemispheres via the corpus callosum and that are critical for bilateral integration of cortical information. Here we report on the identification of a series of genes that individually and in combination define CPN and novel CPN subpopulations during embryonic and postnatal development. We used in situ hybridization analysis, immunocytochemistry, and retrograde labeling to define the layer-specific and neuron-type-specific distribution of these newly identified CPN genes across different stages of maturation. We demonstrate that a subset of these genes (e.g., Hspb3 and Lpl) appear specific to all CPN (in layers II/III and V-VI), whereas others (e.g., Nectin-3, Plexin-D1, and Dkk3) discriminate between CPN of the deep layers and those of the upper layers. Furthermore, the data show that several genes finely subdivide CPN within individual layers and appear to label CPN subpopulations that have not been described previously using anatomical or morphological criteria. The genes identified here likely reflect the existence of distinct programs of gene expression governing the development, maturation, and function of the newly identified subpopulations of CPN. Together, these data define the first set of genes that identify and molecularly subcategorize distinct populations of callosal projection neurons, often located in distinct subdivisions of the canonical cortical laminae.

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Photo of Paola Arlotta

Dr. Arlotta is interested in understanding the molecular laws that govern the birth, differentiation and assembly of the cerebral cortex, the part of the brain that controls how we sense, move and think. She integrates developmental and evolutionary knowledge to investigate therapies for brain repair and for modeling neuropsychiatric disease.

Photo of Jeffrey D. Macklis

Jeffrey Macklis investigates molecular controls and mechanisms over neuron subtype specification, development, diversity, axon guidance-circuit formation, and pathology in the cerebral cortex. His lab seeks to apply developmental controls toward brain and spinal cord regeneration and directed differentiation for in vitro mechanistic modeling using human assembloids.

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