Periostin induces pancreatic regeneration.

We found that the secreted protein periostin (Postn) is highly induced after partial pancreatectomy in regenerating areas containing mesenchymal stroma and tubular complexes. Importantly, after partial pancreatectomy, Postn-deficient mice exhibit impaired mesenchymal formation and reduced regeneration specifically within the pancreatic ß-cell compartment. Furthermore, Postn-deficient mice demonstrate an increased sensitivity to streptozotocin. Notably, injection of Postn directly into the pancreas stimulated proliferation of vimentin-expressing cells within 24 hours, and by 3 days, a mesenchymal stroma was present containing proliferating duct-like cells expressing the progenitor markers Ngn3 and Pdx1. Intraperitoneal injection of Postn resulted in increased numbers of islets and long-term glucoregulatory benefits with no adverse effects found in other tissues. Delivery of Postn throughout the pancreas via the common bile duct resulted in increased numbers of small insulin-expressing clusters and a significant improvement in glucose tolerance. Therefore, Postn is novel molecule capable of potentiating pancreatic ß-cell regeneration.

Muscle function and dysfunction in health and disease.

Skeletal muscles of the trunk and limbs developmentally originate from the cells of the dermomyotomal compartment of the somite. A wealth of knowledge has been accumulated with regard to understanding the molecular regulation of embryonic skeletal myogenesis. Myogenic induction is controlled through a complex series of spatiotemporal dependent signaling cascades. Secreted signaling molecules from surrounding structures not only initiate the myogenic program, but also influence proliferation and differentiation decisions. The proper coordination of these molecular events is thus critical for the formation of physiologically functional skeletal muscles. Hereditary congenital skeletal muscle defects arise due to genetics lesions in myogenic specific components. Understanding the mechanistic routes of congenital skeletal muscle disease therefore requires a comprehensive knowledge of the developmental system. Ultimately, the application of this knowledge will improve the diagnostic and therapeutic methodologies for such diseases. The aim of this review is to overview our current understanding of skeletal muscle development and associated human congenital diseases.