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Deterministic progenitor behavior and unitary production of neurons in the neocortex.

Gao P, Postiglione MP, Krieger TG, Hernandez L, Wang C, Han Z, Streicher C, Papusheva E, Insolera R, Chugh K, Kodish O, Huang K, Simons BD, Luo L, Hippenmeyer S, Shi SH - Cell (2014)

Bottom Line: We found that RGPs progress through a coherent program in which their proliferative potential diminishes in a predictable manner.Removal of OTX1, a transcription factor transiently expressed in RGPs, results in both deep- and superficial-layer neuron loss and a reduction in neuronal unit size.These results suggest that progenitor behavior and histogenesis in the mammalian neocortex conform to a remarkably orderly and deterministic program.

View Article: PubMed Central - PubMed

Affiliation: Developmental Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA; Graduate Program in Neuroscience, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10065, USA.

ABSTRACT
Radial glial progenitors (RGPs) are responsible for producing nearly all neocortical neurons. To gain insight into the patterns of RGP division and neuron production, we quantitatively analyzed excitatory neuron genesis in the mouse neocortex using Mosaic Analysis with Double Markers, which provides single-cell resolution of progenitor division patterns and potential in vivo. We found that RGPs progress through a coherent program in which their proliferative potential diminishes in a predictable manner. Upon entry into the neurogenic phase, individual RGPs produce ?8-9 neurons distributed in both deep and superficial layers, indicating a unitary output in neuronal production. Removal of OTX1, a transcription factor transiently expressed in RGPs, results in both deep- and superficial-layer neuron loss and a reduction in neuronal unit size. Moreover, ?1/6 of neurogenic RGPs proceed to produce glia. These results suggest that progenitor behavior and histogenesis in the mammalian neocortex conform to a remarkably orderly and deterministic program.

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OTX1 Regulates the Production of Deep- and Superficial-Layer Neurons and Unitary Neuronal Output of RGPs(A) Outline of MADM-based mosaic knockout analysis of Otx1 in RGPs undergoing asymmetric neurogenic division. Note that tdTomato labels Otx1–/– cells and EGFP labels wild-type cells within the clone. RG, radial glia; N, neuron; IP, intermediate progenitor.(B) 3D reconstruction images of representative G2-X clones in mosaic Otx1-MADM neocortices. Schematics of the clone are shown at the top.(C) Quantification of the size of the majority population arising from renewing RGPs in mosaic asymmetric neurogenic Otx1-MADM clones (∗∗p < 0.01).(D) Quantification of the size of the minority population arising from IPs or Ns in mosaic asymmetric neurogenic Otx1-MADM clones (n.s., not significant).(E) Quantification of the number of superficial-layer neurons in the majority population (∗p < 0.05).(F) Quantification of the number of deep-layer neurons in the majority population (∗p < 0.05).(G) Quantification of the unitary size of asymmetric neurogenic clones (∗p < 0.05; n.s., not significant).Data are presented as mean ± SEM in (C)–(G). (WT, n = 22 from 5 brains; Otx1–/–, n = 28 from 5 brains). See also Figure S6.
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fig5: OTX1 Regulates the Production of Deep- and Superficial-Layer Neurons and Unitary Neuronal Output of RGPs(A) Outline of MADM-based mosaic knockout analysis of Otx1 in RGPs undergoing asymmetric neurogenic division. Note that tdTomato labels Otx1–/– cells and EGFP labels wild-type cells within the clone. RG, radial glia; N, neuron; IP, intermediate progenitor.(B) 3D reconstruction images of representative G2-X clones in mosaic Otx1-MADM neocortices. Schematics of the clone are shown at the top.(C) Quantification of the size of the majority population arising from renewing RGPs in mosaic asymmetric neurogenic Otx1-MADM clones (∗∗p < 0.01).(D) Quantification of the size of the minority population arising from IPs or Ns in mosaic asymmetric neurogenic Otx1-MADM clones (n.s., not significant).(E) Quantification of the number of superficial-layer neurons in the majority population (∗p < 0.05).(F) Quantification of the number of deep-layer neurons in the majority population (∗p < 0.05).(G) Quantification of the unitary size of asymmetric neurogenic clones (∗p < 0.05; n.s., not significant).Data are presented as mean ± SEM in (C)–(G). (WT, n = 22 from 5 brains; Otx1–/–, n = 28 from 5 brains). See also Figure S6.

Mentions: We introduced the knockout allele of Otx1 (Acampora et al., 1996) into the Emx1-CreERT2/MADM system by genetically linking it to the GT cassette through meiotic recombination; in parallel, the TG cassette was linked to the wild-type allele (Figure 5A). As a result, upon Cre-mediated interchromosomal recombination, the two daughter cells of a RGP undergoing asymmetric neurogenic division exhibited distinct genotypes: the green daughter cell inherited the wild-type allele, whereas the red daughter cell inherited the Otx1 knockout allele. Depending on whether the red daughter cell was a renewing RGP or a differentiating daughter cell (neuron or IP), there were two possible clonal outcomes (Figure 5A).


Deterministic progenitor behavior and unitary production of neurons in the neocortex.

Gao P, Postiglione MP, Krieger TG, Hernandez L, Wang C, Han Z, Streicher C, Papusheva E, Insolera R, Chugh K, Kodish O, Huang K, Simons BD, Luo L, Hippenmeyer S, Shi SH - Cell (2014)

OTX1 Regulates the Production of Deep- and Superficial-Layer Neurons and Unitary Neuronal Output of RGPs(A) Outline of MADM-based mosaic knockout analysis of Otx1 in RGPs undergoing asymmetric neurogenic division. Note that tdTomato labels Otx1–/– cells and EGFP labels wild-type cells within the clone. RG, radial glia; N, neuron; IP, intermediate progenitor.(B) 3D reconstruction images of representative G2-X clones in mosaic Otx1-MADM neocortices. Schematics of the clone are shown at the top.(C) Quantification of the size of the majority population arising from renewing RGPs in mosaic asymmetric neurogenic Otx1-MADM clones (∗∗p < 0.01).(D) Quantification of the size of the minority population arising from IPs or Ns in mosaic asymmetric neurogenic Otx1-MADM clones (n.s., not significant).(E) Quantification of the number of superficial-layer neurons in the majority population (∗p < 0.05).(F) Quantification of the number of deep-layer neurons in the majority population (∗p < 0.05).(G) Quantification of the unitary size of asymmetric neurogenic clones (∗p < 0.05; n.s., not significant).Data are presented as mean ± SEM in (C)–(G). (WT, n = 22 from 5 brains; Otx1–/–, n = 28 from 5 brains). See also Figure S6.
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fig5: OTX1 Regulates the Production of Deep- and Superficial-Layer Neurons and Unitary Neuronal Output of RGPs(A) Outline of MADM-based mosaic knockout analysis of Otx1 in RGPs undergoing asymmetric neurogenic division. Note that tdTomato labels Otx1–/– cells and EGFP labels wild-type cells within the clone. RG, radial glia; N, neuron; IP, intermediate progenitor.(B) 3D reconstruction images of representative G2-X clones in mosaic Otx1-MADM neocortices. Schematics of the clone are shown at the top.(C) Quantification of the size of the majority population arising from renewing RGPs in mosaic asymmetric neurogenic Otx1-MADM clones (∗∗p < 0.01).(D) Quantification of the size of the minority population arising from IPs or Ns in mosaic asymmetric neurogenic Otx1-MADM clones (n.s., not significant).(E) Quantification of the number of superficial-layer neurons in the majority population (∗p < 0.05).(F) Quantification of the number of deep-layer neurons in the majority population (∗p < 0.05).(G) Quantification of the unitary size of asymmetric neurogenic clones (∗p < 0.05; n.s., not significant).Data are presented as mean ± SEM in (C)–(G). (WT, n = 22 from 5 brains; Otx1–/–, n = 28 from 5 brains). See also Figure S6.
Mentions: We introduced the knockout allele of Otx1 (Acampora et al., 1996) into the Emx1-CreERT2/MADM system by genetically linking it to the GT cassette through meiotic recombination; in parallel, the TG cassette was linked to the wild-type allele (Figure 5A). As a result, upon Cre-mediated interchromosomal recombination, the two daughter cells of a RGP undergoing asymmetric neurogenic division exhibited distinct genotypes: the green daughter cell inherited the wild-type allele, whereas the red daughter cell inherited the Otx1 knockout allele. Depending on whether the red daughter cell was a renewing RGP or a differentiating daughter cell (neuron or IP), there were two possible clonal outcomes (Figure 5A).

Bottom Line: We found that RGPs progress through a coherent program in which their proliferative potential diminishes in a predictable manner.Removal of OTX1, a transcription factor transiently expressed in RGPs, results in both deep- and superficial-layer neuron loss and a reduction in neuronal unit size.These results suggest that progenitor behavior and histogenesis in the mammalian neocortex conform to a remarkably orderly and deterministic program.

View Article: PubMed Central - PubMed

Affiliation: Developmental Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA; Graduate Program in Neuroscience, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10065, USA.

ABSTRACT
Radial glial progenitors (RGPs) are responsible for producing nearly all neocortical neurons. To gain insight into the patterns of RGP division and neuron production, we quantitatively analyzed excitatory neuron genesis in the mouse neocortex using Mosaic Analysis with Double Markers, which provides single-cell resolution of progenitor division patterns and potential in vivo. We found that RGPs progress through a coherent program in which their proliferative potential diminishes in a predictable manner. Upon entry into the neurogenic phase, individual RGPs produce ?8-9 neurons distributed in both deep and superficial layers, indicating a unitary output in neuronal production. Removal of OTX1, a transcription factor transiently expressed in RGPs, results in both deep- and superficial-layer neuron loss and a reduction in neuronal unit size. Moreover, ?1/6 of neurogenic RGPs proceed to produce glia. These results suggest that progenitor behavior and histogenesis in the mammalian neocortex conform to a remarkably orderly and deterministic program.

Show MeSH
Related in: MedlinePlus