The CCN family acting throughout the body: recent research developments

The animal body is composed of a variety of cells and extracellular matrices that are organized and orchestrated in a harmonized manner to support life. Therefore, the critical importance of a comprehensive understanding of the molecular network surrounding and integrating the cells is now emphasized. The CCN family is a novel group of matricellular proteins that interact with and orchestrate a number of extracellular signaling and matrix molecules to construct and maintain living tissues. This family comprises six distinct members in mammals, which are characterized by a unique and conserved modular structure. These proteins are not targeted to limited and specific receptors to execute specific missions, but manipulate a vast number of biomolecules in the network by serving as a molecular hub at the center. The unified nomenclature, CCN, originates from a simple acronym of the three classical members, which helps us to avoid having any preconception about their pleiotropic and anonymous functional nature. In this review, after a brief summary of the general molecular concepts regarding the CCN family, new aspects of each member uncovered by recent research are introduced, which represent, nevertheless, only the tip of the iceberg of the profound functionality of these molecules.