Posttranslational Modifications of Bone Collagen Type I are Related to the Function of Rat Femoral Regions

Abstract

This study analyzes the relationship between the function of femoral regions in the rat and the extent of collagen type I posttranslational modifications, to assess whether the different functional roles, i.e., mechanical or metabolic, of the bone tissues are related to the molecular structure of the matrix. For this purpose, 18 female, 100-day-old Sprague-Dawley rats were sacrificed, under anesthesia, and their femurs were removed and dissected free of adhering tissue. The spongy bone of the proximal metaphysis and the diaphysis were then selected as regions exerting prevalently a mechanical function, and the spongy bone of the distal metaphysis was selected as mainly related to metabolic function. Bone prepared from these regions was used to extract and purify the major component of the matrix, type I collagen. The content of hydroxyproline, hydroxylysine, glycosylated hydroxylysine, and pyridinium crosslinks was evaluated and the amount of each compound was expressed as a molar ratio to hydroxyproline. The amount of glycosylated hydroxylysine and pyridinium crosslinks in the distal metaphysis are significantly different from the amounts measured both in the diaphysis and the proximal metaphysis. On the contrary, the amounts of the same compounds in the diaphysis and the proximal metaphysis are statistically the same. The amount of free hydroxylysine, however, appears to be different in the proximal metaphysis and in the diaphysis. The conclusion is that matrix composition differs among different skeletal regions according to the main function they exert.

Vertebrae length and ultra-structure measurements of collagen fibrils and mineral content in the vertebrae of lordotic gilthead seabreams (Sparus aurata)

“…In bone, collagen represents more than 90% of the organic bone matrix. It confers resistance to the structure and establishes the biomechanical properties of the tissue (Moro et al, 2000). Bone quality depends on a number of parameters, such as micro and macro-architecture, bone remodelling rate, microdamage, and properties of the bone matrix, such as size of crystals, mineralization, collagen structure, and crosslinking (Tzaphlidou, 2008).…”

“…It confers resistance to the structure and establishes the biomechanical properties of the tissue (Moro et al, 2000). Fish bones consist of calcium-phosphor hydroxyapatite salts (inorganic part, approximately 65% of the bone's dry mass) embedded in a matrix of type I collagen fibres (organic part) (Weiss and Watabe, 1979;Mahamid et al, 2008).…”

Molecular Characterization of Collagen Hydroxylysine O-Glycosylation by Mass Spectrometry: Current Status

“…[15,16] However, even within the same type of collagen, the amount, type, and distribution of glycosylation appear to depend on the tissue, cell type and pathophysiologic condition. For example, type I collagen is differentially glycosylated depending on functional regions within tissue, [17] maturation stage, [18] and disease state. [19–27] …”

Lysyl Hydroxylase 3-mediated Glucosylation in Type I Collagen

“…The pattern of collagen glycosylation varies depending on collagen types (1,2), functional regions within the same tissue/ same collagen type (13,14), maturation (15)(16)(17), and pathological conditions (18 -25). In bone, type I collagen is relatively less glycosylated (15,26,27); however, in bone/skeletal disorders, such as osteogenesis imperfecta (20, 28 -30), postmenopausal osteoporosis (19,23,31,32), osteosarcoma, osteofibrous dysplasia (21), and Kashin-Beck disease (33), altered collagen glycosylation occurs, and this has been implicated in mineralization defects.…”