Collagens—structure, function, and biosynthesis

Abstract

The extracellular matrix represents a complex alloy of variable members of diverse protein families defining structural integrity and various physiological functions. The most abundant family is the collagens with more than 20 different collagen types identified so far. Collagens are centrally involved in the formation of fibrillar and microfibrillar networks of the extracellular matrix, basement membranes as well as other structures of the extracellular matrix. This review focuses on the distribution and function of various collagen types in different tissues. It introduces their basic structural subunits and points out major steps in the biosynthesis and supramolecular processing of fibrillar collagens as prototypical members of this protein family. A final outlook indicates the importance of different collagen types not only for the understanding of collagen-related diseases, but also as a basis for the therapeutical use of members of this protein family discussed in other chapters of this issue. D

Limb regeneration in a direct‐developing terrestrial salamander, Bolitoglossa ramosi (Caudata: Plethodontidae)

“…4) and could be a reflection of the need for a stiff matrix that could give support and protection to the blastema cells during locomotion in a terrestrial environment. In general, collagen fibers are one of the most abundant proteins of the extracellular matrix, which confers cell protection against mechanical forces (Gelse, Pöschl, & Aigner, 2003). We suggest that the presence of this mature collagen fiber underlying the wound epidermis in B. ramosi could be a protection mechanism for blastema cells during locomotion.…”

Scleraxis is Required for Differentiation of the Stapedius and Tensor Tympani Tendons of the Middle Ear

“…We have shown, rather, that Scx is required for middle ear tendon differentiation, though the underlying molecular mechanism remains elusive. In forelimb tendons of Scxnull embryos, collagen XIV (Gelse et al 2003) and tenomodulin (Brandau et al 2001) expression are lost, and collagen I levels are decreased . Moreover, direct regulation of collagen I enhancers has been demonstrated (Lejard et al 2007;Espira et al 2009).…”

Ultrastructural changes in atherosclerotic plaques following the instillation of airborne particulate matter into the lungs of rabbits

“…The reticulum of dense ECM elements observed within the plaques is structurally similar to that reported by Nakamura et al (46) in aging rats and differs from the normal basal lamina found in nondiseased arteries. Type IV collagen is typically located within the endothelial basal lamina in healthy blood vessel walls (47). The presence of type IV collagen in the dense ECM subtending the endothelium suggests that the observed thickened reticulum subtending the plaque endothelial cells is a modified form of the endothelial basal lamina.…”