Peroxidasin-like protein: expanding the horizons of matrix biology

Abstract

This editorial refers to ‘Peroxidasin-like protein: a novel peroxidase homolog in the human heart’ by Z. Peterfi et al ., doi:10.1093/cvr/cvt256. The extracellular matrix (ECM) is an intertwining network of proteins that provides support to the surrounding cells within a given organ. The ECM consists of collagens, elastins, glycoproteins, proteoglycans, and glycosaminoglycans, and performs a critical function not only during cardiac development and homoeostasis, but also during disease. On the one hand, this function can be structural, allowing for maintained strength and stability. Excessive matrix deposition induces cardiac stiffening, whereas abnormal collagen degradation causes cardiac dilatation.1 On the other hand, this vast entity also acts as a biochemical reservoir for intra- and extracellular communication between the different cardiac cells making the ECM extremely diverse in its function.2 Peterfi et al. 3 describe for the first time a novel peroxidase homologue, peroxidasin-like protein (PXDNL), whose expression is exclusive to the heart. This work follows their previous research describing the role of peroxidasin (PXDN) in matrix deposition following a fibrotic stimulus in the kidney.4 Intriguingly, both these proteins are derived from peroxidase-ancestors and have structural domains characteristic of ‘classical’ ECM proteins ( Figure 1 ). They include leucine-rich repeats similar to a subgroup of proteoglycans, such as decorin, mimecan, biglycan, and lumican, and which …