Exercise prevents β-aminopropionitrile-induced morphological changes to type I collagen in murine bone

Hammond, Max A.; Wallace, Joseph M.

doi:10.1038/bonekey.2015.12

Cited by 16 publications

(26 citation statements)

References 40 publications

(46 reference statements)

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“…This reduction in aldehyde products has been shown in other osteoblast studies to limit the formation of immature covalent and mature multivalent collagen crosslinks [31,32]. In addition, lysyl oxidase inhibition by a lower in vivo BAPN-fumarate concentration of 0.025mM was found to cause a significant shift in D-spacing in mouse bone from another study completed by our group [48]. After compensating for the added fumarate salt, this concentration corresponds to 0.0137mM BAPN, as compared with the 0.137mM BAPN concentration used in the current study.…”

Section: Discussionsupporting

confidence: 60%

“…The same trend was observed in non-mineralized collagen from mouse tail tendon in a study examining the effect of chemical fixation on mouse tail tendon [51]. In contrast, the D-spacing distribution was found to shift toward lower values in mineralized mouse bone collagen with BAPN treatment in vivo [48]. These differences in collagen morphology emphasize the complexity of a crosslink formation process in which in vivo / in vitro lysyl oxidase inhibition, bone/ de novo collagen synthesis, and presence/absence of mineral in the collagen matrix all play a role in allowing decompression of the collagen fibril.…”

Section: Discussionmentioning

confidence: 52%

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β-Aminopropionitrile-Induced Reduction in Enzymatic Crosslinking Causes In Vitro Changes in Collagen Morphology and Molecular Composition

Canelón

Wallace

2016

PLoS ONE

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Type I collagen morphology can be characterized using fibril D-spacing, a metric which describes the periodicity of repeating bands of gap and overlap regions of collagen molecules arranged into collagen fibrils. This fibrillar structure is stabilized by enzymatic crosslinks initiated by lysyl oxidase (LOX), a step which can be disrupted using β-aminopropionitrile (BAPN). Murine in vivo studies have confirmed effects of BAPN on collagen nanostructure and the objective of this study was to evaluate the mechanism of these effects in vitro by measuring D-spacing, evaluating the ratio of mature to immature crosslinks, and quantifying gene expression of type I collagen and LOX. Osteoblasts were cultured in complete media, and differentiated using ascorbic acid, in the presence or absence of 0.25mM BAPN-fumarate. The matrix produced was imaged using atomic force microscopy (AFM) and 2D Fast Fourier transforms were performed to extract D-spacing from individual fibrils. The experiment was repeated for quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Fourier Transform infrared spectroscopy (FTIR) analyses. The D-spacing distribution of collagen produced in the presence of BAPN was shifted toward higher D-spacing values, indicating BAPN affects the morphology of collagen produced in vitro, supporting aforementioned in vivo experiments. In contrast, no difference in gene expression was found for any target gene, suggesting LOX inhibition does not upregulate the LOX gene to compensate for the reduction in aldehyde formation, or regulate expression of genes encoding type I collagen. Finally, the mature to immature crosslink ratio decreased with BAPN treatment and was linked to a reduction in peak percent area of mature crosslink hydroxylysylpyridinoline (HP). In conclusion, in vitro treatment of osteoblasts with low levels of BAPN did not induce changes in genes encoding LOX or type I collagen, but led to an increase in collagen D-spacing as well as a decrease in mature crosslinks.

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Section: Discussionsupporting

confidence: 60%

Section: Discussionmentioning

confidence: 52%

β-Aminopropionitrile-Induced Reduction in Enzymatic Crosslinking Causes In Vitro Changes in Collagen Morphology and Molecular Composition

Canelón

Wallace

2016

PLoS ONE

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“…However, drying bone or removing the organic phase, both of which make cortical bone brittle, caused a reduction in IDI, not the expected increase if IDI is inversely related to toughness . Moreover, for rodent models in which bone brittleness is a dominant characteristic, IDI was found to be higher (type 1 diabetes, chronic kidney disease, and osteogenesis imperfecta) or not different (advanced aging and disruption in crosslinks by lathyrism) compared to respective controls with normal bone toughness. Also, IDI was higher in a mouse model of high ductility (i.e., low brittleness due to hypomineralization) .…”

Section: Discussionmentioning

confidence: 88%

Differences in sensitivity to microstructure between cyclic- and impact-based microindentation of human cortical bone

et al. 2016

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Unlike the known relationships between traditional mechanical properties and microstructural features of bone, the factors that influence the mechanical resistance of bone to cyclic reference point microindention (cRPI) and impact microindention (IMI) have yet to be identified. To determine whether cRPI and IMI properties depend on microstructure, we indented the tibia mid-shaft, the distal radius, and the proximal humerus from 10 elderly donors using the BioDent and OsteoProbe (neighboring sites). As the only output measure of IMI, bone material strength index (BMSi) was significantly different across all 3 anatomical sites being highest for the tibia mid-shaft and lowest for the proximal humerus. Total indentation distance (inverse of BMSi) was higher for the proximal humerus than for the tibia mid-shaft but was not different between other anatomical comparisons. As a possible explanation for the differences in BMSi, pore water, as determined by 1H nuclear magnetic resonance, was lowest for the tibia and highest for the humerus. Moreover, the local intra-cortical porosity, as determined by micro-computed tomography, was negatively correlated with BMSi for both arm bones. BMSi was however positively correlated with peak bending stress of cortical bone extracted from the tibia mid-shaft. Microstructural correlations with cRPI properties were not significant for any of the bones. The one exception was that average energy dissipated during cRPI was negatively correlated with local tissue mineral density in the tibia mid-shaft. With higher indentation force and larger tip diameter than cRPI, only IMI appears to be sensitive to the underlying porosity of cortical bone.

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“…While blocking lysyl oxidase (LOX) function with β-aminopropionitrile alters D-spacing distribution and fl/fl:Cre mice have reduced LOX expression, enzymatic crosslinks are not likely to contribute to the D-spacing shift noted here given the shift is not in the expected direction and crosslink maturity was not significantly affected despite reduced LOX expression. (14, 20) …”

Section: Discussionmentioning

confidence: 99%

“…From each error image, 2D Fast Fourier Transforms (2D FFTs) were performed on 10–15 fibrils (50–60 fibrils per bone) to obtain an individual fibril’s D-spacing from the first harmonic peak of the power spectrum as previously described. (17, 19, 20) …”

Section: Methodsmentioning

confidence: 99%

Removing or truncating connexin 43 in murine osteocytes alters cortical geometry, nanoscale morphology, and tissue mechanics in the tibia

Hammond

Berman

Pacheco‐Costa

et al. 2016

Bone

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Gap junctions are formed from ubiquitously expressed proteins called connexins that allow the transfer of small signaling molecules between adjacent cells. Gap junctions are especially important for signaling between osteocytes and other bone cell types. The most abundant type of connexin in bone is connexin 43 (Cx43). The C-terminal domain of Cx43 is thought to be an important modulator of gap junction function but the role that this domain plays in regulating tissue-level mechanics is largely unknown. We hypothesized that the lack of the C-terminal domain of Cx43 would cause morphological and compositional changes as well as differences in how bone responds to reference point indentation (RPI) and fracture toughness testing. The effects of the C-terminal domain of Cx43 in osteocytes and other cell types were assessed in a murine model (C57BL/6 background). Mice with endogenous Cx43 in their osteocytes removed via a Cre-loxP system were crossed with knock-in mice which expressed Cx43 that lacked the C-terminal domain in all cell types due to the insertion of a truncated allele to produce the four groups used in the study. The main effect of removing the C-terminal domain from osteocytic Cx43 increased cortical mineral crystallinity (p=0.036) and decreased fracture toughness (p=0.017). The main effect of the presence of the C-terminal domain in other cell types increased trabecular thickness (p<0.001), cortical thickness (p=0.008), and average RPI unloading slope (p=0.004). Collagen morphology was altered when either osteocytes lacked Cx43 (p=0.008) or some truncated Cx43 was expressed in all cell types (p<0.001) compared to controls but not when only the truncated form of Cx43 was expressed in osteocytes (p=0.641). In conclusion, the presence of the C-terminal domain of Cx43 in osteocytes and other cell types is important to maintain normal structure and mechanical integrity of bone.

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Exercise prevents β-aminopropionitrile-induced morphological changes to type I collagen in murine bone

Cited by 16 publications

References 40 publications

β-Aminopropionitrile-Induced Reduction in Enzymatic Crosslinking Causes In Vitro Changes in Collagen Morphology and Molecular Composition

β-Aminopropionitrile-Induced Reduction in Enzymatic Crosslinking Causes In Vitro Changes in Collagen Morphology and Molecular Composition

Differences in sensitivity to microstructure between cyclic- and impact-based microindentation of human cortical bone

Removing or truncating connexin 43 in murine osteocytes alters cortical geometry, nanoscale morphology, and tissue mechanics in the tibia

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