The Na,K-
ATPase is composed of multiple
isoforms and the
isoform distribution varies with the tissue and during development. The alpha1
isoform for example, is the major
isoform in the kidney and many other tissues, while the alpha2
isoform is the predominate one in skeletal muscle. All three
isoforms are found in the brain although in adult rodent brain, the alpha 3
isoform is located essentially in neurons while the alpha2
isoform is found in astrocytes and some limited neuronal populations. Interestingly the alpha 4
isoform is found exclusively in the mid region of the sperm tail. The distribution of the
isoforms of the Na,K-
ATPase has been extensively studied in many tissues and during development. The examples cited above provide some indication to the diversity of Na,K-
ATPase isoform expression. In order to understand the significance of this distribution, we have developed animals which lack the alpha1, alpha2, and alpha 3
isoforms. It is anticipated that these studies will provide insight into the role that these
isoforms play in driving various biological processes in specific tissues. Here we describe some of our studies which deal with the behavioral aspects of the alpha1, alpha2, and alpha 3 deficient mice, particularly those that are haploinsufficient in one
isoform i.e. lacking one functional gene for the alpha1, alpha2, or alpha 3
isoforms. Such studies are important as two human diseases are associated with deficiency in the alpha2 and alpha 3
isoforms. These are
Familial Hemiplegic Migraine type 2 and
Rapid-Onset Dystonia Parkinsonism, these diseases result from alpha2 and alpha 3
isoform haploinsufficiency, respectively. We find that the haploinsufficiency of both alpha2 and alpha 3
isoforms result in behavioral defects.