Biology subjects

Duer, M. J.

Publications and source records attributed to Duer, M. J..

5 recordsLinked to original sources

bioRxiv2025

Inorganic pyrophosphate disrupts amorphous hydrated bone mineral interfaces in hypophosphatasia

Bone mineral molecular architecture is tightly regulated by the kinetics of calcium phosphate phase transformations. In the rare skeletal disease hypophosphatasia (HPP), caused by inactivating mutations in the ALPL gene encoding tissue-nonspecific alkaline phosphatase (TNSALP), accumulation of inorganic pyrophosphate (PPi) alters these phase dynamics. Using solid-state nuclear magnetic resonance spectroscopy and high-resolution electron microscopy, in patient samples we show that bone mineral from compound heterozygous HPP patients exhibits a loss of hydrated amorphous interfacial phases and instead contains highly crystalline hydroxyapatite (HAP), correlating with abnormally high bone mineral density and brittle atypical femoral fractures. Synthetic and cellular models demonstrate that elevated PPi impedes normal phase transitions from amorphous calcium phosphate precursors, bypassing intermediate states and driving ordered HAP nucleation. These findings link disrupted mineral phase kinetics to pathological bone mineral molecular structure, emphasising the critical importance of the hydrated amorphous shell around bone mineral for its material properties and redefining HPP as a molecular mineralization disorder. Our findings also illustrate how biochemical cues regulate non-equilibrium crystallization pathways in biomineralization.

biophysics↗

bioRxiv2025

Lysyl oxidase-mediated intermolecular crosslinks fine-tune collagen I molecular dynamics and regulate cell-matrix interactions through focal adhesions

Lysyl oxidase (LOX)-mediated intermolecular crosslinking is essential for collagen I fibril stability, yet its influence on collagen molecular conformation and dynamics, and the downstream consequences for cell-matrix interactions remain poorly understood. Here, we genetically modulated LOX in collagen I-producing MC3T3-E1 cells to generate matrices with elevated (overexpression, OX) or absent (knockout, KO) crosslinking. Enhanced crosslinking yielded thick, continuous, aligned fibrils, whereas reduced crosslinking produced friable, dissociated fibrils. Solid-state nuclear magnetic resonance spectroscopy (SSNMR) revealed local triple-helix unfolding and altered nanosecond- and microsecond-scale molecular motions in both OX and KO matrices, changes largely reversible upon decellularization, implicating a synergistic role of crosslinking chemistry and cell-applied forces in regulating the dynamically-accessible conformations of collagen I. Changes in the molecular structure and dynamics of collagen had a functional impact on cell adhesion and mechanotransduction. These findings identify collagen crosslinking as a tunable element of the extracellular matrix "mechanical code," integrating biochemical modification with molecular-scale mechanics to regulate cell-matrix adhesion and mechanosignalling.

biophysics↗

bioRxiv2025

Preserving Integrity: Innovative In Vitro Methods for Extracellular Matrix Decellularization and Collagen Purification

BackgroundIn tissue engineering and cell therapy development, synthetic biomaterials are frequently supplemented with collagen or other extracellular matrix (ECM) components to enhance biocompatibility. To support these applications, novel methods for collagen purification and ECM decellularization were developed, with a focus on preserving the structural and biochemical integrity of the final products. ResultsThe effectiveness of these methods was validated using solid-state NMR and fluorescence spectroscopy, bright-field and confocal microscopy, amino acid analysis, and transmission electron microscopy. Intact cells were dislodged from ECM-producing cultures through the application of cytoskeleton-targeting drugs, while the native protein composition of the ECM was maintained. In parallel, collagen purified using chymotrypsin was shown to retain its native triple-helical structure and post-translational modifications. ConclusionsBoth techniques are broadly applicable to various cell types capable of producing collagen and/or ECM in vitro, thereby expanding the availability of species- and tissue-specific sources. These advances hold particular promise for human-relevant tissue engineering and drug discovery applications.

bioengineering↗

bioRxiv2025

A Novel FNDC1-NAMPT-NAD axis is Implicated in Small and Large-vessel Arterial Disease and Drives Vascular Calcification

Vascular calcification represents a convergent pathological feature of diverse cardiovascular diseases, yet the upstream molecular programs orchestrating this process remain poorly defined. Here, we uncover fibronectin type III domain-containing 1 (FNDC1) as a previously unrecognized regulator of vascular calcification across both microvascular and macrovascular beds. Integrative transcriptomic profiling of human calciphylaxis lesions and atherosclerotic coronaries identified FNDC1 as one of the most significantly upregulated genes. In primary human vascular smooth muscle cells, FNDC1 drove osteogenic phenotype switch and vascular calcification through activation of PI3K/AKT signaling and metabolic reprogramming. Mechanistically, FNDC1 directly binds to nicotinamide phosphoribosyltransferase (NAMPT) resulting in elevated intracellular NAD levels, thus coupling vascular signaling to control of NAD biosynthesis. In murine models, genetic deletion of Fndc1 or pharmacologic inhibition of NAMPT suppressed arterial calcification and prolonged survival. Clinically, circulating FNDC1 levels were elevated in patients with both calciphylaxis and coronary artery disease and independently predicted cardiovascular risk in 42,687 UK Biobank participants. Together, these findings establish FNDC1 as a central mediator of vascular pathology and highlight the FNDC1- NAMPT-NAD+ axis as a promising target for therapeutic intervention.

cell biology↗

bioRxiv2024

Poly(ADP-ribose) binding sites on collagen I fibrils for nucleating intrafibrillar bone mineral

Bone calcification is essential for vertebrate life. The mechanism by which mineral ions are transported into collagen fibrils to induce intrafibrillar mineral formation requires a calcium binding biopolymer that also has highly selective binding to the collagen fibril hole zones where intrafibrillar calcification begins, over other bone extracellular matrix components. Poly(ADP-ribose) has been shown to be a candidate biopolymer for this process and we show here that poly(ADP-ribose) has high affinity, highly conserved binding sites in the collagen type I C-terminal telopeptides. The discovery of these poly(ADP-ribose)-collagen binding sites gives new insights into the chemical mechanisms underlying bone calcification and possible mechanisms behind pathologies where there is dysfunctional bone calcification.

biophysics↗