Journal of Neuroscience, Vol 14, 511-522, Copyright © 1994 by Society for Neuroscience
Kv3.3b: a novel Shaw type potassium channel expressed in terminally differentiated cerebellar Purkinje cells and deep cerebellar nuclei
DS Goldman-Wohl, E Chan, D Baird and N Heintz
Howard Hughes Medical Institute, Rockefeller University, New York, New York 10021.
A two-step hybridization/subtraction procedure was employed to isolate
markers for the later stages of Purkinje cell differentiation. From this
screen, a novel Shaw potassium channel cDNA (Kv3.3b) was identified that is
developmentally regulated. Expression of this channel is highly enriched in
the brain, particularly in the cerebellum, where its expression is confined
to Purkinje cells and deep cerebellar nuclei. Sequence analysis revealed
that it is an alternatively spliced form of the mouse Kv3.3 gene, and that
the previously reported Kv3.3 mRNA (Ghanshani et al., 1992) is not
expressed in cerebellum. Expression of the Kv3.3b mRNA begins in cerebellar
Purkinje cells between postnatal day 8 (P8) and P10 and continues through
adulthood, coinciding with elaboration of the mature Purkinje cell
dendritic arbor. The timing of expression of Kv3.3b mRNA is maintained in
mixed, dissociated primary cerebellar cell culture. These results suggest
that the Kv3.3b K+ channel function is restricted to terminally
differentiated Purkinje cells, and that analysis of the mechanisms
governing its expression in vivo and in vitro can reveal molecular
mechanisms governing Purkinje cell differentiation.