Altered patterns of neuron production in the p27Kip1 knockout mouse

The number and distribution of neurons in the murine neocortex are altered by loss of function of p27(Kip1), a cyclin-dependent kinase inhibitor that regulates cell cycle progression at the G(1) phase. We show that a temporary decline in the production of non-GABAergic projection neurons occurs in the dorsomedial neopallium of the p27Kip1 knockout mouse during the mid-term of neuronogenesis. It is followed by an augmentation of neuron production later in neuronogenesis leading to an increased production of projection neurons for the upper layers of the neocortex ( layers II - IV). p27(Kip1) is likely to play a critical role in cell internal regulatory mechanisms of proliferation/differentiation behavior of neural progenitor cells and may be directly involved in the control of neuron number during the period when non-GABAergic projection neurons for layers II - IV are being produced. Copyright (C) 2004 S. Karger AG, Basel.