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Synchronous symmetry breaking in neurons with different neurite counts.

Wissner-Gross ZD, Scott MA, Steinmeyer JD, Yanik MF - PLoS ONE (2013)

Bottom Line: However, the effects of neurite count in neuronal symmetry breaking have never been studied.We also show that despite the significant differences among the previously proposed models, they all agree with our experimental findings when the expression levels of the proteins responsible for symmetry breaking increase with neurite count.Consistent with these results, we observe that the expression levels of two of these proteins, HRas and shootin1, significantly correlate with neurite count.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Harvard University, Cambridge, Massachusetts, USA.

ABSTRACT
As neurons develop, several immature processes (i.e., neurites) grow out of the cell body. Over time, each neuron breaks symmetry when only one of its neurites grows much longer than the rest, becoming an axon. This symmetry breaking is an important step in neurodevelopment, and aberrant symmetry breaking is associated with several neuropsychiatric diseases, including schizophrenia and autism. However, the effects of neurite count in neuronal symmetry breaking have never been studied. Existing models for neuronal polarization disagree: some predict that neurons with more neurites polarize up to several days later than neurons with fewer neurites, while others predict that neurons with different neurite counts polarize synchronously. We experimentally find that neurons with different neurite counts polarize synchronously. We also show that despite the significant differences among the previously proposed models, they all agree with our experimental findings when the expression levels of the proteins responsible for symmetry breaking increase with neurite count. Consistent with these results, we observe that the expression levels of two of these proteins, HRas and shootin1, significantly correlate with neurite count. This coordinated symmetry breaking we observed among neurons with different neurite counts may be important for synchronized polarization of neurons in developing organisms.

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Dynamics of neuron polarization as defined by Eq. (1).A, Polarity versus time. The solid line is a linear fit to the data. B, Polarity versus total neurite length. Total neurite length was binned at intervals of 20 µm. The solid line is a Gaussian fit to the data, with an inflection point at 114 µm suggesting a phase transition between unpolarized and polarized states. The nonlinearity of this data agrees with previous work on the polarization of neurons with exactly two neurites [19].
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pone-0054905-g002: Dynamics of neuron polarization as defined by Eq. (1).A, Polarity versus time. The solid line is a linear fit to the data. B, Polarity versus total neurite length. Total neurite length was binned at intervals of 20 µm. The solid line is a Gaussian fit to the data, with an inflection point at 114 µm suggesting a phase transition between unpolarized and polarized states. The nonlinearity of this data agrees with previous work on the polarization of neurons with exactly two neurites [19].

Mentions: Using Eq. (1), we observed an increasing polarity as a function of time (p < 10−10 by Pearson correlation, Fig. 2A), as well as the expected phase transition in polarity as total neurite length exceeded approximately 100 µm (Fig. 2B), consistent with our previously reported results in neurons with exactly two neurites [19]. The specific number of neurons at each time point can be found in Table S1.


Synchronous symmetry breaking in neurons with different neurite counts.

Wissner-Gross ZD, Scott MA, Steinmeyer JD, Yanik MF - PLoS ONE (2013)

Dynamics of neuron polarization as defined by Eq. (1).A, Polarity versus time. The solid line is a linear fit to the data. B, Polarity versus total neurite length. Total neurite length was binned at intervals of 20 µm. The solid line is a Gaussian fit to the data, with an inflection point at 114 µm suggesting a phase transition between unpolarized and polarized states. The nonlinearity of this data agrees with previous work on the polarization of neurons with exactly two neurites [19].
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3569465&req=5

pone-0054905-g002: Dynamics of neuron polarization as defined by Eq. (1).A, Polarity versus time. The solid line is a linear fit to the data. B, Polarity versus total neurite length. Total neurite length was binned at intervals of 20 µm. The solid line is a Gaussian fit to the data, with an inflection point at 114 µm suggesting a phase transition between unpolarized and polarized states. The nonlinearity of this data agrees with previous work on the polarization of neurons with exactly two neurites [19].
Mentions: Using Eq. (1), we observed an increasing polarity as a function of time (p < 10−10 by Pearson correlation, Fig. 2A), as well as the expected phase transition in polarity as total neurite length exceeded approximately 100 µm (Fig. 2B), consistent with our previously reported results in neurons with exactly two neurites [19]. The specific number of neurons at each time point can be found in Table S1.

Bottom Line: However, the effects of neurite count in neuronal symmetry breaking have never been studied.We also show that despite the significant differences among the previously proposed models, they all agree with our experimental findings when the expression levels of the proteins responsible for symmetry breaking increase with neurite count.Consistent with these results, we observe that the expression levels of two of these proteins, HRas and shootin1, significantly correlate with neurite count.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Harvard University, Cambridge, Massachusetts, USA.

ABSTRACT
As neurons develop, several immature processes (i.e., neurites) grow out of the cell body. Over time, each neuron breaks symmetry when only one of its neurites grows much longer than the rest, becoming an axon. This symmetry breaking is an important step in neurodevelopment, and aberrant symmetry breaking is associated with several neuropsychiatric diseases, including schizophrenia and autism. However, the effects of neurite count in neuronal symmetry breaking have never been studied. Existing models for neuronal polarization disagree: some predict that neurons with more neurites polarize up to several days later than neurons with fewer neurites, while others predict that neurons with different neurite counts polarize synchronously. We experimentally find that neurons with different neurite counts polarize synchronously. We also show that despite the significant differences among the previously proposed models, they all agree with our experimental findings when the expression levels of the proteins responsible for symmetry breaking increase with neurite count. Consistent with these results, we observe that the expression levels of two of these proteins, HRas and shootin1, significantly correlate with neurite count. This coordinated symmetry breaking we observed among neurons with different neurite counts may be important for synchronized polarization of neurons in developing organisms.

Show MeSH
Related in: MedlinePlus