Collagen formation, function and role in kidney disease.

Highly abundant in mammals, collagens define the organization of tissues and participate in cell signalling. Most of the 28 vertebrate collagens, with the exception of collagens VI, VII, XXVI and XXVIII, can be categorized into five subgroups: fibrillar collagens, network-forming collagens, fibril-associated collagens with interrupted triple helices, membrane-associated collagens with interrupted triple helices and multiple triple-helix domains with interruptions. Collagen peptides are synthesized from the ribosome and enter the rough endoplasmic reticulum, where they undergo numerous post-translational modifications. The collagen chains form triple helices that can be secreted to form a diverse array of supramolecular structures in the extracellular matrix. Collagens are ubiquitously expressed and have been linked to a broad spectrum of disorders, including genetic disorders with kidney phenotypes. They also have an important role in kidney fibrosis and mass spectrometry-based proteomic studies have improved understanding of the composition of fibrosis in kidney disease. A wide range of therapeutics are in development for collagen and kidney disorders, including genetic approaches, chaperone therapies, protein degradation strategies and anti-fibrotic therapies. Improved understanding of collagens and their role in disease is needed to facilitate the development of more specific treatments for collagen and kidney disorders.