Biology subjects

Lories, R.

Publications and source records attributed to Lories, R..

7 recordsLinked to original sources

bioRxiv2026

FERMT2 expression in human articular chondrocytes is regulated by hypoxia-associated transcriptional programs

Objective: Kindlin-2, encoded by FERMT2, is a focal adhesion protein essential for cartilage homeostasis and mechanotransduction. While loss of Kindlin-2 in mice induces osteoarthritis (OA)-like pathology, the upstream mechanisms regulating its expression in human cartilage remain unknown. Methods: A bioinformatics pipeline was applied to the FERMT2 promoter to predict transcriptional regulators, followed by network and enrichment analyses. Predicted candidates were validated by siRNA knockdown in the human C28/I2 chondrocyte cell line and in primary OA chondrocytes. Pathway enrichment highlighted hypoxia-related regulators, which were further tested by hypoxia mimetic treatment (IOX2) and culture under low oxygen (1% O2). Gene expression changes were quantified by qPCR, and effects on extracellular matrix (ECM) markers were assessed. Results: In silico analysis identified 21 candidate transcription factors, of which GATA1, MEF2A, and RBPJ were validated as regulators of FERMT2. Silencing of GATA1 and MEF2A reduced FERMT2 expression, whereas RBPJ knockdown increased FERMT2 in both C28/I2 cells and primary OA chondrocytes. However, RBPJ silencing also reduced ACAN and increased COL1A1, suggesting detrimental effects on ECM homeostasis. Enrichment analysis revealed a strong association between FERMT2 regulation and hypoxia pathways, supported by conserved hypoxia response elements in the promoter. Experimentally, both IOX2 and 1% O2 significantly upregulated FERMT2 expression in primary chondrocytes. Hypoxia also increased anabolic ECM genes and reduced catabolic enzymes, but these effects occurred independently of Kindlin-2. Conclusions: This study identifies hypoxia as a novel regulator of kindlin-2 expression in human cartilage, providing new insight into the upstream control of this molecule in osteoarthritis. While additional transcription factors such as GATA1, MEF2A, and RBPJ contribute to FERMT2 regulation, only hypoxia consistently enhanced FERMT2 expression without adverse ECM effects.

molecular biology↗

bioRxiv2026

Interplay between canonical Wnt signaling and α5β1 integrins modulates mechanoresponse in human articular cartilage

ObjectivesMechanical cues are essential for maintaining cartilage function, yet how they integrate with molecular pathways dysregulated in osteoarthritis (OA) remains poorly defined in human tissue. Canonical Wnt signalling influences cartilage biology and cell-matrix interactions, but its role in integrin-dependent mechanoregulation in human cartilage is not fully understood. This study aimed to determine how Wnt activation affects chondrocyte responses to physiological mechanical loading, with a focus on 5{beta}1integrin and cytoskeletal organisation. MethodsHuman cartilage explants from non-OA and OA donors were subjected to short-term physiological cyclic compression. Canonical Wnt signalling was activated with CHIR99021, and integrin-mediated adhesion was modulated using the 5{beta}1 blocking peptide ATN-161 during loading. Chondrocyte responses were assessed by analysing mechanoresponsive and matrix-related gene expression, 5{beta}1 complex formation via proximity ligation assay and actin cytoskeletal organisation by confocal microscopy. ResultsOA chondrocytes exhibited a distinct integrin profile, characterised by increased ITGA5 and ITGB1 but reduced ITGA10 expression. In non-OA cartilage, canonical Wnt activation increased ITGB1 expression and 5{beta}1 integrin complex formation, while mechanical loading further enhanced ITGA5 and ITGB1 transcription under Wnt-activated conditions. Under control conditions, loading induced mechanoresponsive and anabolic gene expression in non-OA cartilage; these responses were attenuated following Wnt-activation and partially restored by 5{beta}1 blockade. Mechanical loading induced F-actin reorganization toward a more cortical distribution across cartilage zones, irrespective of disease status or treatment. Wnt activation did not result in distinct cytoskeletal phenotypes under load, and load-induced actin remodelling was comparable between groups. ConclusionThese findings identify 5{beta}1integrin as a key mediator linking canonical Wnt signalling to altered chondrocyte mechanoresponsiveness in human cartilage. While mechanical loading consistently induced cortical F-actin reorganization, Wnt-associated changes in load responsiveness arose primarily from integrin-dependent mechanisms rather than major alterations in actin organization. This study highlights the complexity of cartilage mechanoregulation and identifies integrin-mediated signaling as important contributors to canonical Wnt-driven alterations in load responsiveness relevant to OA.

molecular biology↗

bioRxiv2026

SHIP2 deletion in cartilage does not modulate osteoarthritis in a post-traumatic mouse model

ObjectivesThe inositol phosphatase SHIP2 plays a crucial role in skeletal development and chondrocyte differentiation, and mutations in INPPL1 (encoding SHIP2) cause opsismodysplasia, a chondrodysplasia with marked cartilage abnormalities. We investigated whether SHIP2 contributes to structural joint remodeling in osteoarthritis (OA). MethodsA cartilage-specific conditional knockout of SHIP2 was generated using Ship2fl/fl mice crossed with AggrecanCreERT2 mice. OA was induced at 9 weeks of age via destabilization of the medial meniscus (DMM). Sham surgery served as control. Mice were sacrificed 12 weeks post-surgery. Histological evaluation of articular cartilage, synovium, osteophytes, and subchondral bone was performed. Chondrocyte hypertrophy was assessed by type X collagen (COLX) staining, and SHIP1 was evaluated as a potential compensatory mechanism. ResultsDMM surgery induced OA-like changes in all genotypes, including cartilage damage, synovial inflammation, osteophyte formation, and subchondral bone thickening. However, Ship2cCART-KO mice showed no differences in OA-related parameters compared to control littermates. COLX expression increased following DMM surgery, independent of SHIP2 deletion. SHIP1 protein levels were not elevated in SHIP2-deficient mice. ConclusionThese findings indicate that SHIP2, while essential for cartilage development, does not act as a structural disease modifier in post-traumatic OA, suggesting that within this context, SHIP2 is not required for maintaining adult articular cartilage structure and is unlikely to represent a major therapeutic target for modifying structural disease progression.

molecular biology↗

bioRxiv2024

Joint and tissue mechanics in post-traumatic osteoarthritis: insights from the rat model

ObjectiveAltered mechanical loading is a known risk factor for osteoarthritis. Destabilization of the medial meniscus (DMM) is a preclinical gold standard model for post-traumatic osteoarthritis and is thought to induce instability and locally increased loading. However, the joint- and tissue-level mechanical environment underlying cartilage degeneration remains poorly documented. DesignUsing a custom multiscale modeling approach, we assessed joint and tissue biomechanics in rats undergoing sham surgery and DMM. High-fidelity experimental gait data were collected in a setup combining biplanar fluoroscopy and a ground reaction force plate. Knee poses and joint-level loading were estimated through musculoskeletal modeling, using bony landmarks, semi-automatically tracked via deep learning on fluoroscopic images, and ground reaction forces. A musculoskeletal model of the rat hindlimb was adapted to represent knee flexion-extension, valgus-varus, and internal-external rotation. The tissue-level cartilage mechanical environment was then spatially estimated, using the musculoskeletal modeling parameters as inputs into a dedicated finite element (FE) model of the rat knee, comprising cartilage and meniscal tissues. Experimental gait data and modeling workflows, including musculoskeletal models and FE meshes, are openly shared through a data repository. ResultsIn rats with DMM, the frontal plane knee pose was altered, yet there was no indication of joint-level overloading. Tissue-level mechanical cues typically linked with cartilage degeneration were not increased in the medial tibial cartilage, despite evidence of tissue structural changes. ConclusionDMM did not increase joint and tissue mechanical responses in the knee medial compartment, suggesting that mechanical loading alone does not explain the observed osteoarthritis-like structural changes.

bioengineering↗

bioRxiv2021

Hypoxia induces transcription of DOT1L in articular cartilage to protect against osteoarthritis

Osteoarthritis is the most prevalent joint disease worldwide and a leading source of pain and disability. To date, this disease lacks curative treatment as underlying molecular mechanisms remain largely unknown. The histone methyltransferase DOT1L protects against osteoarthritis, and DOT1L-mediated H3K79 methylation is reduced in human and mouse osteoarthritic joints. Thus, restoring DOT1L function seems to be critical to preserve joint health. However, DOT1L-regulating molecules and networks remain elusive, in the joint and beyond. Here, we identify transcription factors and networks that regulate DOT1L gene expression using a novel bioinformatics pipeline. Thereby, we unravel an undiscovered link between the hypoxia pathway and DOT1L. We provide unprecedented evidence that hypoxia enhances DOT1L expression and H3K79 methylation via hypoxia-inducible factor-1 alpha (HIF-1). Importantly, we demonstrate that DOT1L contributes to the protective effects of hypoxia in articular cartilage and osteoarthritis. Intra-articular treatment with a selective hypoxia mimetic in mice after surgical induction of osteoarthritis restores DOT1L function and stalls disease progression. Collectively, our data unravel a novel molecular mechanism that protects against osteoarthritis with hypoxia inducing DOT1L transcription in cartilage. Local treatment with a selective hypoxia mimetic in the joint restores DOT1L function and could be an attractive therapeutic strategy for osteoarthritis.

cell biology↗

bioRxiv2021

ANP32A represses Wnt signaling across tissues tissues thereby protecting against joint and heart disease

Wnt signaling is key to diverse homeostatic and pathological processes. This cascade is hyper-activated in osteoarthritis, the most common joint disease. Yet, fundamental aspects of Wnt signaling remain undiscovered. Here, we report that ANP32A negatively regulates Wnt signaling across tissues. In cartilage, loss of Anp32a triggered Wnt hyper-activation. Mechanistically, ANP32A directly interacted with Wnt pathway components and inhibited Wnt target genes via histone acetylation masking. Wnt antagonist treatment reduced severity of osteoarthritis in Anp32a-deficient mice preventing osteophyte formation, contrasting with cartilage-protective effects of ANP32A on oxidative stress. Hence, dual therapy targeting Wnt signaling and oxidative stress in Anp32a-deficient mice ameliorated more osteoarthritis features than individual treatments. Anp32a loss also resulted in Wnt hyper-activation in the heart with cardiac hypertrophy, and in the hippocampus, shedding light on mechanisms for reported links between ANP32A and Alzheimers disease. Collectively, this work reveals that ANP32A is a translationally relevant repressor of Wnt signaling, impacting homeostasis and disease across tissues.

cell biology↗

bioRxiv2019

Radiosafe micro-computed tomography for longitudinal evaluation of murine disease models

Implementation of in vivo high-resolution micro-computed tomography (CT), a powerful tool for longitudinal analysis of murine lung disease models, is hampered by the lack of data on cumulative low-dose radiation effects on the investigated disease models. We aimed to measure radiation doses and effects of repeated CT scans, to establish cumulative radiation levels and scan protocols without relevant toxicity. Lung metastasis, inflammation and fibrosis models and healthy mice were weekly scanned over one-month with CT using high-resolution respiratory-gated 4D and expiration-weighted 3D protocols, comparing 5-times weekly scanned animals with controls. Radiation dose was measured by ionization chamber, optical fiberradioluminescence probe and thermoluminescent detectors in a mouse phantom. Dose effects were evaluated by in vivo CT and bioluminescence imaging read-outs, gold standard endpoint evaluation and blood cell counts. Weekly exposure to 4D CT, dose of 540-699 mGy/scan, did not alter lung metastatic load nor affected healthy mice. We found a disease-independent decrease in circulating blood platelets and lymphocytes after repeated 4D CT. This effect was eliminated by optimizing a 3D protocol, reducing dose to 180-233 mGy/scan while maintaining equally high-quality images. We established CT safety limits and protocols for weekly repeated whole-body acquisitions with proven safety for the overall health status, lung, disease process and host responses under investigation, including the radiosensitive blood cell compartment.

physiology↗