Development of a top-down MS assay for specific identification of human periostin isoforms

Periostin is a matricellular protein encoded by the POSTN gene that is alternatively spliced to produce ten different isoforms of periostin with a molecular weight ranging from 78 to 91 kDa. Periostin is known to promote fibrillogenesis, organize the extracellular matrix, and bind integrin-receptors to induce cell signaling. Periostin is a key component of the wound healing process but is also known to participate in the pathogenesis of different diseases including atopic dermatitis, asthma, and cancer. In both health and disease, the functions of the different periostin isoforms are largely unknown. The ability to precisely determine the isoform profile of a given human sample is fundamental for characterizing their functional significance. Identification of periostin isoforms is most often carried out at the transcriptional level using RT-PCR based approaches. Though, it must be recognized that periostin exerts it functions at the translational level and is an extracellular protein making it impossible to derive transcriptional information for e.g. plasma periostin that is spatially disconnected from the cell it was expressed by. Consequently, monitoring periostin isoforms at the protein level is highly advantageous. In the publication connected to this dataset we present a fully developed top down mass spectrometry assay for identification and quantification of periostin splice isoforms from any human sample at the protein level.