“Compensatory” transcriptional mechanisms: Comparison of transcriptomes of Cx43 null and knockdown astrocytes

ABSTRACT: Our previous studies on brains and hearts of Cx null mice have revealed that expression level, control and coordination of a very large number of genes are regulated compared to wildtype littermates. This result suggests the possibility that the phenotype of the Cx null animals may include genes not only linked to the intracellular communication that gap junction channels provide but also to genes with very different functions. The question often arises, however, of the degree to which “compensation” occurs in knockouts such that gene regulation depends on pathways altered to make up for the missing gene rather than reflecting normal gene interlinkage. In order to explore this question in the Cx43 null setting, we have compared gene expression patterns in Cx43 null astrocytes with that in wildtype astrocytes acutely treated (36 hrs) with Cx43 siRNA. In these studies, Cx43 levels determined by Western blot analysis were reduced by at least 70% following siRNA treatment, comparable with the 3.24x downregulation for mRNA. For each group of astrocytes, four independent cultures were compared, using oligonucleotide microarrays printed with the mouse Qiagen library. 8060 well annotated unigenes were identifiable in all 8 arrays; of these, 8.2% were upregulated and 6.0% downregulated in Cx43 null astrocytes and 6.2% upreguated and 7.0 downregulated in siRNA treated astrocytes. Interestingly, regulation of 92.3% unigenes significantly regulated in both Cx43 deficient astrocytes had the same orientation, representing a highly significant overlap of gene expression alteration. These experiments thus indicate that the gene regulation in Cx43 null astrocytes is largely due to direct interlinkage rather than to developmental compensation for the missing gene. Keywords: genetic modification

ORGANISM(S): Mus musculus

PROVIDER: GSE8168 | GEO | 2007/06/20

SECONDARY ACCESSION(S): PRJNA101065

REPOSITORIES: GEO