collagen fibril organization

Definition

Target type: biologicalprocess

Any process that determines the size and arrangement of collagen fibrils within an extracellular matrix. [GOC:mah, ISBN:0815316194]

Collagen fibril organization is a complex and highly regulated process that is essential for the structural integrity of tissues throughout the body. It involves a series of steps that begin with the synthesis of collagen molecules within cells and culminate in the formation of mature, cross-linked fibrils.

1. **Collagen Synthesis:** Collagen fibrils are assembled from individual collagen molecules, which are synthesized by fibroblasts and other cell types. The synthesis of collagen begins with the transcription of collagen genes, resulting in the production of mRNA molecules that encode the amino acid sequence of collagen proteins. The mRNA molecules are then translated into polypeptide chains called procollagen alpha chains.

2. **Hydroxylation and Glycosylation:** Once synthesized, procollagen alpha chains undergo post-translational modifications, including hydroxylation and glycosylation. Hydroxylation involves the addition of hydroxyl groups to specific proline and lysine residues in the procollagen alpha chains. This modification is essential for the formation of stable collagen triple helices and is catalyzed by enzymes called prolyl hydroxylases and lysyl hydroxylases. Glycosylation involves the addition of sugar molecules to specific hydroxylysine residues in the procollagen alpha chains.

3. **Triple Helix Formation:** Three procollagen alpha chains assemble into a triple helical structure, forming a procollagen molecule. The triple helix is stabilized by hydrogen bonds between the amino acid residues of the three alpha chains. The formation of the triple helix is a critical step in collagen fibril organization as it imparts the characteristic strength and flexibility of collagen fibers.

4. **Secretion and Cleavage:** Procollagen molecules are then secreted from the cell into the extracellular matrix. Once in the extracellular matrix, procollagen molecules undergo further processing by peptidases called procollagen peptidases. Procollagen peptidases cleave the terminal non-helical regions of the procollagen molecule, resulting in the formation of mature collagen molecules.

5. **Fibril Assembly:** Mature collagen molecules self-assemble into fibrils, which are long, cylindrical structures that provide strength and support to tissues. The assembly of collagen fibrils is a highly organized process that is influenced by a variety of factors, including the concentration of collagen molecules, the pH of the environment, and the presence of other extracellular matrix proteins.

6. **Cross-linking:** Collagen fibrils are further stabilized by cross-linking, which is a process that involves the formation of covalent bonds between collagen molecules. Cross-linking is catalyzed by enzymes called lysyl oxidases and results in the formation of a strong, insoluble network of collagen fibers. The degree of cross-linking increases with age, which contributes to the decreased elasticity and increased stiffness of tissues in older individuals.

The process of collagen fibril organization is a dynamic process that is influenced by a variety of factors. Disruptions in this process can lead to a variety of diseases, including osteogenesis imperfecta, Ehlers-Danlos syndrome, and scurvy. Research into the mechanisms of collagen fibril organization is ongoing and has the potential to lead to new therapies for these and other diseases.'
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Proteins (10)

Compounds (363)