Journal of Neuroscience, Vol 14, 6384-6391, Copyright © 1994 by Society for Neuroscience
MN20, a D2 cyclin found in brain, is implicated in neural differentiation
ME Ross and M Risken
Department of Neurology, University of Minnesota, Minneapolis 55455.
Cyclins are regulatory proteins that promote the progression of dividing
cells through the cell cycle. D-type cyclins are important mediators of the
transition from G1 into S phase of the cell cycle and are thought to be
widely expressed in mitotically active tissues (Matsushime et al., 1991b;
Inaba et al., 1992; Xiong et al., 1992). We report the isolation of a cDNA
clone, MN20, which represents a D2 cyclin message form whose expression
pattern is highly restricted to brain. MN20 is not ubiquitous, but rather
it is expressed only in restricted neuronal precursor populations, for
example, in proliferating granule neuroblasts of the cerebellum but not
hippocampus. Strikingly, MN20 expression is also found in postmitotic
neuronal precursor cells of the embryonic cerebral cortex, but not in the
dividing cortical neuroblasts. These observations suggest that the D2
cyclin gene serves regionally specific functions in neuronal
differentiation, some of which may be distinct from the promotion of cell
cycle progression and which act at the interface between mitosis and the
assumption of mature neuronal morphology.
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