Spontaneous Polarization of a Developing Neuron
08/09/09, 13:30 at Room 3631 (6th floor of building 3 of the Faculty of Sciences)
Cell polarity is spontaneously established even in a symmetrical condition. This process is regulated not only by intracellular chemical reactions but also by active transportations of proteins, and involved in changes in cellular morphologies. In this study, I have theoretically sought a general framework of such cellular polarization. To this end, I constructed a simple biophysical model of a developing neuron, in which a cell initially has several neurites with similar lengths, but only one of them abruptly elongate so as to be an axon. The model assumed stochastic transportations of a key molecule from soma to a growth cone and a bistable switch for axon specification at a growth cone, which is activated by the transported molecule. My mathematical analysis revealed logic of neuronal polarization. Interestingly, in my model, if multiple neurites are simultaneously selected, this polarization will be cancelled out. Also, I analytically derived a condition of such robust polarization. My model is consistent with many experimental observations. |
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