Astrocytes express specific variants of CaM KII ? and ?, but not ? and ?, that determine their cellular localizations

Publisher Website
Google Scholar
Abstract
Multiple isoforms of type II Ca2+‐calmodulin‐dependent kinase (CaM KII) are composed of two major neuron‐specific subunits, designated α and β, and two less well‐characterized subunits that are also expressed in non‐neuronal tissues, designated δ and γ. Regulated expression of these 4 gene products, and several variants produced by alternative splicing, shows temporal and regional specificity and influences intracellular targeting. We used immunoblotting and RT‐PCR to analyze subunit and variant expression and distribution in cultured cerebellar astrocytes and neurons, and whole cerebellar cortex from rodent brain. The data indicate that: (i) astrocytes express a single splice variant of δ, namely δ2; (ii) like neurons, astrocytes express two forms of CaM KII γ; γB and γA; (iii) these CaM KII variants are enriched in the supernate fraction in astrocytes, and the particulate fraction in neurons; (iv) unlike neurons, astrocytes do not express detectable levels of α or β subunits or their respective splice variants. The results indicate that neurons and astrocytes express distinct CaM KII subunits and variants that localize to distinct subcellular compartments and, by inference, exert distinct cellular functions. GLIA 30:154–164, 2000.