Limits...
Differential expression of lumican and fibromodulin regulate collagen fibrillogenesis in developing mouse tendons.

Ezura Y, Chakravarti S, Oldberg A, Chervoneva I, Birk DE - J. Cell Biol. (2000)

Bottom Line: With development, the amount of lumican decreases to barely detectable levels while fibromodulin increases significantly, and these changing patterns may regulate this process.The observed increased ratio of fibromodulin to lumican and a competition for the same binding site could mediate these transitions.These studies indicate that lumican and fibromodulin have different developmental stage and leucine-rich repeat protein specific functions in the regulation of fibrillogenesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.

ABSTRACT
Collagen fibrillogenesis is finely regulated during development of tissue-specific extracellular matrices. The role(s) of a leucine-rich repeat protein subfamily in the regulation of fibrillogenesis during tendon development were defined. Lumican-, fibromodulin-, and double-deficient mice demonstrated disruptions in fibrillogenesis. With development, the amount of lumican decreases to barely detectable levels while fibromodulin increases significantly, and these changing patterns may regulate this process. Electron microscopic analysis demonstrated structural abnormalities in the fibrils and alterations in the progression through different assembly steps. In lumican-deficient tendons, alterations were observed early and the mature tendon was nearly normal. Fibromodulin-deficient tendons were comparable with the lumican- in early developmental periods and acquired a severe phenotype by maturation. The double-deficient mice had a phenotype that was additive early and comparable with the fibromodulin-deficient mice at maturation. Therefore, lumican and fibromodulin both influence initial assembly of intermediates and the entry into fibril growth, while fibromodulin facilitates the progression through growth steps leading to mature fibrils. The observed increased ratio of fibromodulin to lumican and a competition for the same binding site could mediate these transitions. These studies indicate that lumican and fibromodulin have different developmental stage and leucine-rich repeat protein specific functions in the regulation of fibrillogenesis.

Show MeSH

Related in: MedlinePlus

Collagen fibril structure during development in wild-type mouse tendons. Transmission electron micrographs of transverse sections from mouse flexor tendons from normal mice (a–d). Fibril structure was analyzed at different developmental stages, 4 d (a), 10 d (b), 1 mo (c), and 3 mo (d) postnatal. Bar, 300 nm.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2169450&req=5

Figure 1: Collagen fibril structure during development in wild-type mouse tendons. Transmission electron micrographs of transverse sections from mouse flexor tendons from normal mice (a–d). Fibril structure was analyzed at different developmental stages, 4 d (a), 10 d (b), 1 mo (c), and 3 mo (d) postnatal. Bar, 300 nm.

Mentions: Fibrils were analyzed in cross sections of tendons from 2 d to 7.5 mo in wild-type mice. Relative to specific stages in chicken tendon development, electron microscopic analysis of mouse tendons identified 4 d, 10 d, 1 mo, and 3 mo as representative of different steps in fibrillogenesis (Fig. 1). In the early postnatal period, characterized by the 4-d tendon, the collagen fibrils all had relatively small diameters (64 ± 12 nm, mean ± SD). By 10-d postnatal, the fibril diameters were heterogeneous, with larger diameter fibrils present, in addition to smaller diameter fibrils characteristic of 4 d. By 1 mo, there was a broad distribution of fibril diameters with large diameter fibrils being characteristic of this stage. From 1 to 3 mo, the fibril diameters changed only modestly with the largest diameter fibrils being more prominent in the oldest tendons. The specific stages described were defined as representative of the initial assembly of immature fibril intermediates (4 d), the transition from fibril assembly to growth (10 d), and fibril growth to maturation (1–3 mo). The 3-mo tendon is characteristic of a mature tendon that has completed growth.


Differential expression of lumican and fibromodulin regulate collagen fibrillogenesis in developing mouse tendons.

Ezura Y, Chakravarti S, Oldberg A, Chervoneva I, Birk DE - J. Cell Biol. (2000)

Collagen fibril structure during development in wild-type mouse tendons. Transmission electron micrographs of transverse sections from mouse flexor tendons from normal mice (a–d). Fibril structure was analyzed at different developmental stages, 4 d (a), 10 d (b), 1 mo (c), and 3 mo (d) postnatal. Bar, 300 nm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2169450&req=5

Figure 1: Collagen fibril structure during development in wild-type mouse tendons. Transmission electron micrographs of transverse sections from mouse flexor tendons from normal mice (a–d). Fibril structure was analyzed at different developmental stages, 4 d (a), 10 d (b), 1 mo (c), and 3 mo (d) postnatal. Bar, 300 nm.
Mentions: Fibrils were analyzed in cross sections of tendons from 2 d to 7.5 mo in wild-type mice. Relative to specific stages in chicken tendon development, electron microscopic analysis of mouse tendons identified 4 d, 10 d, 1 mo, and 3 mo as representative of different steps in fibrillogenesis (Fig. 1). In the early postnatal period, characterized by the 4-d tendon, the collagen fibrils all had relatively small diameters (64 ± 12 nm, mean ± SD). By 10-d postnatal, the fibril diameters were heterogeneous, with larger diameter fibrils present, in addition to smaller diameter fibrils characteristic of 4 d. By 1 mo, there was a broad distribution of fibril diameters with large diameter fibrils being characteristic of this stage. From 1 to 3 mo, the fibril diameters changed only modestly with the largest diameter fibrils being more prominent in the oldest tendons. The specific stages described were defined as representative of the initial assembly of immature fibril intermediates (4 d), the transition from fibril assembly to growth (10 d), and fibril growth to maturation (1–3 mo). The 3-mo tendon is characteristic of a mature tendon that has completed growth.

Bottom Line: With development, the amount of lumican decreases to barely detectable levels while fibromodulin increases significantly, and these changing patterns may regulate this process.The observed increased ratio of fibromodulin to lumican and a competition for the same binding site could mediate these transitions.These studies indicate that lumican and fibromodulin have different developmental stage and leucine-rich repeat protein specific functions in the regulation of fibrillogenesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.

ABSTRACT
Collagen fibrillogenesis is finely regulated during development of tissue-specific extracellular matrices. The role(s) of a leucine-rich repeat protein subfamily in the regulation of fibrillogenesis during tendon development were defined. Lumican-, fibromodulin-, and double-deficient mice demonstrated disruptions in fibrillogenesis. With development, the amount of lumican decreases to barely detectable levels while fibromodulin increases significantly, and these changing patterns may regulate this process. Electron microscopic analysis demonstrated structural abnormalities in the fibrils and alterations in the progression through different assembly steps. In lumican-deficient tendons, alterations were observed early and the mature tendon was nearly normal. Fibromodulin-deficient tendons were comparable with the lumican- in early developmental periods and acquired a severe phenotype by maturation. The double-deficient mice had a phenotype that was additive early and comparable with the fibromodulin-deficient mice at maturation. Therefore, lumican and fibromodulin both influence initial assembly of intermediates and the entry into fibril growth, while fibromodulin facilitates the progression through growth steps leading to mature fibrils. The observed increased ratio of fibromodulin to lumican and a competition for the same binding site could mediate these transitions. These studies indicate that lumican and fibromodulin have different developmental stage and leucine-rich repeat protein specific functions in the regulation of fibrillogenesis.

Show MeSH
Related in: MedlinePlus