Expression of α-dystrobrevin in blood-tissue barriers: sub-cellular localisation and molecular characterisation in normal and dystrophic mice

The α- and β-dystrobrevins (DBs) belong to a family of dystrophin-related and dystrophin-associated proteins that are members of the dystrophin-associated protein complex (DAPC). This complex provides a link between the cytoskeleton and the extracellular matrix or other cells. However, specific functions of the two dystrobrevins remain largely unknown, with α-DB being believed to have a role mainly in skeletal muscle. Here, we describe previously unknown expression patterns and the localisation and molecular characteristics of α-DB isoforms in non-muscle mouse tissues. We demonstrate a highly specific sub-cellular distribution of α-DB in organs forming blood-tissue barriers. We show α-DB expression and localisation in testicular Sertoli cells, stomach and respiratory epithelia and provide electron-microscopic evidence for its immunolocalisation in these cells and in the central nervous system. Moreover, we present the molecular characterisation of α-DB transcript in these tissues and provide evidence for a distinct heterogeneity of associations between α-DB and dystrophins and utrophin in normal and dystrophic non-muscle tissues. Together, our results indicate that α-DB, in addition to its role in skeletal muscle, may also be required for the proper function of specific non-muscle tissues and that disruption of DAPC might lead to tissue-blood barrier abnormalities.