Expression Analysis Using Oligonucleotide Microarrays in Mice Lacking Bradykinin Type 2 Receptors

We ecently conducted detailed cardiovascular and blood pressure-related phenotypic studies of mice lacking the bradykinin-B2 receptor and were unable to identify a phenotype despite insensitivity to infused bradykinin. We therefore used oligonucleotide microarray analysis of some 12 000 genes and expressed sequence tags to identify molecular mechanisms that might be involved in compensating for the lack of a functional B2 receptor in the kidneys of the mice. We identified 2 gene families that may have an impact on cardiovascular regulation and the bradykinin pathway. A water transport channel in the kidney, AQP4, was downregulated in the mice, whereas other members of the gene family did not show differences in expression levels. In addition, a number of serine proteases were upregulated in B2 receptor-deficient mice. These genes are all located within a gene cluster on mouse chromosome 7. The findings were verified by an independent method. We suggest that microarray analysis has usefulness in elucidating otherwise unappreciated compensatory signaling pathways.