Collagen XII mediated cellular and extracellular mechanisms in development, regeneration, and disease

Expression, optimization and biological activity analysis of recombinant type XII collagen in Pichia pastoris

Collagen XII (COL12A1) is a type of FACIT collagen that plays an important role in the extracellular matrix structuring, participating in the regulation of collagen fiber size, and serves as a link between different components of the extracellular matrix. However, it is still unclear whether exogenous administration of collagen XII has a direct regulatory effect. In this study, we successfully produced recombinant human XII-type collagen (rh12C) through genetic engineering approach, which is composed of different functional domains. A Pichia pastoris host cell strain was constructed based on the intracellular translation regulatory mechanism of collagen, achieving a maximum yield of 4.89 g/L. After purification and structural characterization of the protein, its potential biological efficacy was evaluated through in vitro cell experiments.

Collagen XII deficiency promotes ligament-specific heterotopic ossification via fibrochondrocyte differentiation

Heterotopic ossification of tendons and ligaments causes pain and dysfunction, significantly reducing quality of life. However, its underlying mechanisms remain elusive. In addition to injury, tissue organization and stiffness have been implicated in heterotopic ossification. Collagen XII, a member of the fibril-associated collagens with interrupted triple helices (FACIT) family, plays a crucial role in maintaining the structural integrity and function of tendons and ligaments. Its deficiency alters tissue stiffness and predisposes ligaments to rupture. In this study, we investigated whether collagen XII contributes to the development of heterotopic ossification. Three-dimensional microcomputed tomography (3D-μCT) and X-ray analyses revealed heterotopic bone formation in the knee and ankle ligaments, but not in tendons, of Col12a1-deficient mice, with a 100 % incidence in mice older than 19 weeks. Histological analysis showed the presence of Alcian blue- and Toluidine blue-positive fibrochondrocyte-like cells in Col12a1-deficient ligaments, which were subsequently replaced by bone tissue, as indicated by Alizarin red staining. Real-time qPCR analysis of knee ligaments demonstrated a slight increase in chondrogenic markers and a significant upregulation of osteogenic markers in Col12a1-deficient mice compared with wild-type controls. In vitro chondrogenesis and osteogenesis assays using primary tenocytes from wild-type and Col12a1-deficient mice revealed that collagen XII deficiency enhanced osteogenic potential, whereas chondrogenic potential remained comparable. Our findings indicate that collagen XII deficiency specifically induces heterotopic bone formation in knee and ankle ligaments, occurring via fibrochondrocytes rather than through endochondral or intramembranous ossification.

Abnormal collagen deposition mediated by cartilage oligomeric matrix protein in the pathogenesis of oral submucous fibrosis

Abnormal accumulation of collagen fibrils is a hallmark feature of oral submucous fibrosis (OSF). However, the precise characteristics and underlying mechanisms remain unclear, impeding the advancement of potential therapeutic approaches. Here, we observed that collagen I, the main component of the extracellular matrix, first accumulated in the lamina propria and subsequently in the submucosa of OSF specimens as the disease progressed. Using RNA-seq and Immunofluorescence in OSF specimens, we screened the cartilage oligomeric matrix protein (COMP) responsible for the abnormal collagen accumulation. Genetic COMP deficiency reduced arecoline-stimulated collagen I deposition significantly in vivo. In comparison, both COMP and collagen I were upregulated under arecoline stimulation in wild-type mice. Human oral buccal mucosal fibroblasts (hBMFs) also exhibited increased secretion of COMP and collagen I after stimulation in vitro. COMP knockdown in hBMFs downregulates arecoline-stimulated collagen I secretion. We further demonstrated that hBMFs present heterogeneous responses to arecoline stimulation, of which COMP-positive fibroblasts secrete more collagen I. Since COMP is a molecular bridge with Fibril-associated collagens with Interrupted Triple helices (FACIT) in the collagen network, we further screened and identified collagen XIV, a FACIT member, co-localizing with both COMP and collagen I. Collagen XIV expression increased under arecoline stimulation in wild-type mice, whereas it was hardly expressed in the Comp-/- mice, even with under stimulation. In summary, we found that COMP may mediates abnormal collagen I deposition by functions with collagen XIV during the progression of OSF, suggesting its potential to be targeted in treating OSF.

Inhibitory effect on endometrial cancer: Collagen type XII α1 chain

Objective

Endometrial cancer (EC) is one of the most common gynecological malignancies, and it poses a considerable threat to women's lives. Therefore, searching for EC inhibitors and exploring the potential mechanism of action is particularly important. This article aims to investigate the potential effect of collagen type XII α1 chain (COL12A1) on macrophage polarization and its subsequent influence on the biological behavior of EC cells to further elucidate the underlying mechanisms of EC development.

Material and Methods

Quantitative real-time polymerase chain reaction and Western blot were used to detect the expression levels of COL12A1 messenger RNA and protein in EC cells. A subcutaneous tumor formation assay was performed in nude mice to evaluate the effect of COL12A1 on EC cell growth in vivo. Flow cytometry was utilized to assess the expression levels of macrophage surface markers under different treatments. Cell counting kit-8, Transwell assay, and Western blot experiments were conducted to investigate the effects of COL12A1 knockdown and various macrophage treatments on the biological behavior of EC cells.

Results

The expression of COL12A1 was upregulated in EC cells. Knockdown of COL12A1 significantly inhibited the viability, invasion, migration, and extracellular matrix abilities of EC cells and tumor growth in vivo. Overexpression of COL12A1 significantly promoted M2-type macrophage polarization, which enhanced the invasion, migration, and epithelial-mesenchymal transition abilities of EC cells.

Conclusion

The expression of COL12A1 is upregulated in EC, and COL12A1 promotes EC cell invasion and migration by activating macrophage M2 polarization.

Structural extracellular matrix-mediated molecular signaling in wound repair and tissue regeneration

The extracellular matrix (ECM) is a complex, non-cellular network of molecules that offers structural support for cells and tissues. The ECM is composed of various structural components, including collagen, fibronectin, laminin, perlecan, nidogen, tenascin, and fibulin, which are capable of binding to each other and to cell-to-adhesion receptors, endowing the ECM with unique physical and biochemical properties that are essential for its function in maintaining health and managing disease. Over the past three decades, extensive research has shown that the core of the ECM can significantly impact cellular events at the molecular level. Structural modifications have also been strongly associated with tissue repair. Through interactions with cells, matrix proteins regulate critical processes such as cell proliferation and differentiation, migration, and apoptosis, essential for maintaining tissue homeostasis, formation, and regeneration. This review emphasizes the interlocking networks of ECM macromolecules and their primary roles in tissue regeneration and wound repair. Through studying ECM dynamics, researchers have discovered molecular signaling pathways that demonstrate how the ECM influences protein patterns and open up more possibilities for developing therapeutics that target the ECM to enhance wound repair and tissue regeneration.

The Association of Genetic Variants Within the Type XII Collagen and Tenascin C Genes with Knee Joint Laxity Measurements

BACKGROUND/OBJECTIVES

Types I, V, and XI collagen gene variants have been reported to associate with measurements of knee joint laxity and/or absolute knee ligament length changes. Type XII collagen and tenascin C are also ligament structural proteins whose expression is regulated by mechanical loading. This study investigated whether COL12A1 and TNC variants are associated with knee laxity and/or ligament length changes.

METHODS

Genu recurvatum, anterior-posterior tibial translation, external-internal tibial rotation, and ligament length changes were measured in 128 healthy participants. They were genotyped for COL12A1 (rs970547) and TNC (rs1061494, rs2104772, rs1138545).

RESULTS

Both the COL12A1 AA and TNC rs1061494 TT genotypes were associated with decreased external (p = 0.007, p = 0.010) and internal (p = 0.025, p = 0.002) rotation, as well as slack (p = 0.033, p = 0.014), in the dominant leg. Both genotypes, together with sex, weight, and/or COL1A1 genotypes, explained 26% and 32% of the variance in external and internal rotation, respectively. The TNC genotype, sex, and BMI explained 23% of the variance in slack. The COL12A1 AA and the TNC rs1061494 TT genotypes were associated with smaller changes in the MCL (aMCL: COL12A1 p = 0.009, TNC p = 0.045; iMCL: COL12A1 p = 0.004, TNC p = 0.043; pMCL: COL12A1 p = 0.003, TNC p = 0.067; aDMCL: COL12A1 p = 0.007, TNC p = 0.020; pDMCL: COL12A1 p = 0.007, TNC p = 0.023) and/or LCL (COL12A1 p = 0.652, TNC p = 0.049) lengths within the dominant knee. The TNC rs1061494 CC genotype was associated with larger changes in the non-dominant anterior (p = 0.021) and posterior (p < 0.001) ACL bundle lengths.

CONCLUSIONS

These findings suggest that COL12A1 and TNC variants are associated with internal-external tibial rotation and knee ligament length changes in healthy individuals.

Impact of High Glucose on Bone Collagenous Matrix Composition, Structure, and Organization: An Integrative Analysis Using an Ex Vivo Model

Diabetes mellitus is a widespread metabolic disorder linked to numerous systemic complications, including adverse effects on skeletal health, such as increased bone fragility and fracture risk. Emerging evidence suggests that high glucose may disrupt the extracellular matrix (ECM) of bone, potentially altering its composition and organization. Collagen, the primary organic component of the ECM, is critical for maintaining structural integrity and biomechanical properties. However, definitive evidence and a comprehensive understanding of the molecular mechanisms through which high glucose impacts the ECM and collagen remain elusive. This study employed an ex vivo embryonic chicken femur model to investigate the effects of high glucose on the collagenous matrix. A comprehensive approach integrating histological evaluation, histomorphometry, ATR-FTIR spectroscopy, and proteomics was adopted to unravel structural, biochemical, and molecular changes in the ECM. Histomorphometric analysis revealed disrupted collagen fibril architecture, characterized by altered fibril diameter, alignment, and spatial organization. ATR-FTIR spectroscopy highlighted biochemical modifications, including non-enzymatic glycation that impaired collagen crosslinking and reduced matrix integrity. Proteomic profiling unveiled significant alterations in ECM composition and function, including downregulation of key collagen crosslinking enzymes and upregulation of inflammatory and coagulation pathways. High glucose profoundly disrupts the collagenous matrix of bone, weakening its structural integrity and organization. These findings emphasize the critical impact of high glucose environments on extracellular matrix composition and bone quality, offering insights into the mechanisms behind diabetic bone fragility and guiding future research toward targeted therapeutic strategies.

Microbial collagenases: an updated review on their characterization, degradation mechanisms, and current applications

Collagen, recognized as a fundamental protein present in biological tissues and structures, plays a crucial role in maintaining organ structure and tissue integrity. Microbial collagenases are specific for the degradation of collagen. The specific three-stranded helix region of natural collagen can be identified and hydrolyzed by microbial collagenases under physiological conditions, producing collagen peptides with high physiological activity. This article describes microbial collagenases, providing an introduction to the structure, physiological characteristics, factors affecting enzyme activity, and hydrolysis mechanisms of various classes of these enzymes. Microbial collagenase is the most widely used class of collagenase and plays an important role in all aspects of human life, and various applications of microbial collagenases in food industry, healthcare and environmental protection will be addressed in this review. In addition to its beneficial functions, microbial collagenase can exist as a virulence factor for pathogenic bacteria, and enhanced research on its structure and mechanism of action will help us to investigate more effective inhibitors as well as therapeutic agents and tools for the treatment of the corresponding diseases. Finally, this review critically analyses existing challenges and outlines prospects for future advancements in the field.

Collagen as the extracellular matrix biomaterials in the arena of medical sciences

Collagen is a multipurpose material that has several applications in the health care, dental care, and pharmaceutical industries. Crosslinked compacted solids or lattice-like gels can be made from collagen. Biocompatibility, biodegradability, and wound-healing properties make collagen a popular scaffold material for cardiovascular, dentistry, and bone tissue engineering. Due to its essential role in the control of several of these processes, collagen has been employed as a wound-healing adjunct. It forms a major component of the extracellular matrix and regulates wound healing in its fibrillar or soluble forms. Collagen supports cardiovascular and other soft tissues. Oral wounds have been dressed with resorbable forms of collagen for closure of graft and extraction sites, and to aid healing. This present review is concentrated on the use of collagen in bone regeneration, wound healing, cardiovascular tissue engineering, and dentistry.

The shared molecular mechanism of spinal cord injury and sarcopenia: a comprehensive genomics analysis

Introduction

The occurrence of Spinal cord injury (SCI) brings economic burden and social burden to individuals, families and society, and the complications after SCI greatly affect the rehabilitation and treatment of patients in the later stage.This study focused on the potential biomarkers that co-exist in SCI and sarcopenia, with the expectation to diagnose and prognose patients in the acute phase and rehabilitation phase using comprehensive data analysis.

Methods

The datasets used in this study were downloaded from Gene Expression Omnibus (GEO) database. Firstly, the datasets were analyzed with the "DEseq2" and "Limma" R package to identify differentially expressed genes (DEGs), which were then visualized using volcano plots. The SCI and sarcopenia DEGs that overlapped were used to construct a protein-protein interaction (PPI) network. Three algorithms were used to obtain a list of the top 10 hub genes. Next, validation of the hub genes was performed using three datasets. According to the results, the top hub genes were DCN, FSTL1, and COL12A1, which subsequently underwent were Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses. We also assessed immune cell infiltration with the CIBERSORT algorithm to explore the immune cell landscape. The correlations between the hub genes and age and body mass index were investigated. To illustrate the biological mechanisms of the hub genes more clearly, a single-cell RNA-seq dataset was assessed to determine gene expression when muscle injury occurred. According to our analysis and the role in muscle, we chose the fibro/adipogenic progenitors (FAPs) cluster in the next step of the analysis. In the sub cluster analysis, we use the "Monocle" package to perform the trajectory analysis in different injury time points and different cell states.

Results

A total of 144 overlapped genes were obtained from two datasets. Following PPI network analysis and validation, we finally identified three hub-genes (DCN, FSTL1, and COL12A1), which were significantly altered in sarcopenic SCI patients both before and after rehabilitation training. The three hub genes were also significantly expressed in the FAPs clusters. Furthermore, following injury, the expression of the hub genes changed with the time points, changing in FAPs cluster.

Discussion

Our study provides comprehensive insights into how muscle changes after SCI are associated with sarcopenia by moving from RNA-seq to RNA-SEQ, including Immune infiltration landscape, pesudotime change and so on. The three hub genes identified in this study could be used to distinguish the sarcopenia state at the genomic level. Additionally, they may also play a prognostic role in evaluating the efficiency of rehabilitation training.

Protein glycosylation in cardiovascular health and disease

Protein glycosylation, which involves the attachment of carbohydrates to proteins, is one of the most abundant protein co-translational and post-translational modifications. Advances in technology have substantially increased our knowledge of the biosynthetic pathways involved in protein glycosylation, as well as how changes in glycosylation can affect cell function. In addition, our understanding of the role of protein glycosylation in disease processes is growing, particularly in the context of immune system function, infectious diseases, neurodegeneration and cancer. Several decades ago, cell surface glycoproteins were found to have an important role in regulating ion transport across the cardiac sarcolemma. However, with very few exceptions, our understanding of how changes in protein glycosylation influence cardiovascular (patho)physiology remains remarkably limited. Therefore, in this Review, we aim to provide an overview of N-linked and O-linked protein glycosylation, including intracellular O-linked N-acetylglucosamine protein modification. We discuss our current understanding of how all forms of protein glycosylation contribute to normal cardiovascular function and their roles in cardiovascular disease. Finally, we highlight potential gaps in our knowledge about the effects of protein glycosylation on the heart and vascular system, highlighting areas for future research.

Assessment of the proteome profile of decellularized human amniotic membrane and its biocompatibility with umbilical cord-derived mesenchymal stem cells

Extracellular matrix-based bio-scaffolds are useful for tissue engineering as they retain the unique structural, mechanical, and physiological microenvironment of the tissue thus facilitating cellular attachment and matrix activities. However, considering its potential, a comprehensive understanding of the protein profile remains elusive. Herein, we evaluate the impact of decellularization on the human amniotic membrane (hAM) based on its proteome profile, physicochemical features, as well as the attachment, viability, and proliferation of umbilical cord-derived mesenchymal stem cells (hUC-MSC). Proteome profiles of decellularized hAM (D-hAM) were compared with hAM, and gene ontology (GO) enrichment analysis was performed. Proteomic data revealed that D-hAM retained a total of 249 proteins, predominantly comprised of extracellular matrix proteins including collagens (collagen I, collagen IV, collagen VI, collagen VII, and collagen XII), proteoglycans (biglycan, decorin, lumican, mimecan, and versican), glycoproteins (dermatopontin, fibrinogen, fibrillin, laminin, and vitronectin), and growth factors including transforming growth factor beta (TGF-β) and fibroblast growth factor (FGF) while eliminated most of the intracellular proteins. Scanning electron microscopy was used to analyze the epithelial and basal surfaces of D-hAM. The D-hAM displayed variability in fibril morphology and porosity as compared with hAM, showing loosely packed collagen fibers and prominent large pore areas on the basal side of D-hAM. Both sides of D-hAM supported the growth and proliferation of hUC-MSC. Comparative investigations, however, demonstrated that the basal side of D-hAM displayed higher hUC-MSC proliferation than the epithelial side. These findings highlight the importance of understanding the micro-environmental differences between the two sides of D-hAM while optimizing cell-based therapeutic applications.

The coordinated activities of collagen VI and XII in maintenance of tissue structure, function and repair: evidence for a physical interaction

Collagen VI and collagen XII are structurally complex collagens of the extracellular matrix (ECM). Like all collagens, type VI and XII both possess triple-helical components that facilitate participation in the ECM network, but collagen VI and XII are distinct from the more abundant fibrillar collagens in that they also possess arrays of structurally globular modules with the capacity to propagate signaling to attached cells. Cell attachment to collagen VI and XII is known to regulate protective, proliferative or developmental processes through a variety of mechanisms, but a growing body of genetic and biochemical evidence suggests that at least some of these phenomena may be potentiated through mechanisms that require coordinated interaction between the two collagens. For example, genetic studies in humans have identified forms of myopathic Ehlers-Danlos syndrome with overlapping phenotypes that result from mutations in either collagen VI or XII, and biochemical and cell-based studies have identified accessory molecules that could form bridging interactions between the two collagens. However, the demonstration of a direct or ternary structural interaction between collagen VI or XII has not yet been reported. This Hypothesis and Theory review article examines the evidence that supports the existence of a functional complex between type VI and XII collagen in the ECM and discusses potential biological implications.

Collagen VI Deficiency Impairs Tendon Fibroblasts Mechanoresponse in Ullrich Congenital Muscular Dystrophy

The pericellular matrix (PCM) is a specialized extracellular matrix that surrounds cells. Interactions with the PCM enable the cells to sense and respond to mechanical signals, triggering a proper adaptive response. Collagen VI is a component of muscle and tendon PCM. Mutations in collagen VI genes cause a distinctive group of inherited skeletal muscle diseases, and Ullrich congenital muscular dystrophy (UCMD) is the most severe form. In addition to muscle weakness, UCMD patients show structural and functional changes of the tendon PCM. In this study, we investigated whether PCM alterations due to collagen VI mutations affect the response of tendon fibroblasts to mechanical stimulation. By taking advantage of human tendon cultures obtained from unaffected donors and from UCMD patients, we analyzed the morphological and functional properties of cellular mechanosensors. We found that the length of the primary cilia of UCMD cells was longer than that of controls. Unlike controls, in UCMD cells, both cilia prevalence and length were not recovered after mechanical stimulation. Accordingly, under the same experimental conditions, the activation of the Hedgehog signaling pathway, which is related to cilia activity, was impaired in UCMD cells. Finally, UCMD tendon cells exposed to mechanical stimuli showed altered focal adhesions, as well as impaired activation of Akt, ERK1/2, p38MAPK, and mechanoresponsive genes downstream of YAP. By exploring the response to mechanical stimulation, for the first time, our findings uncover novel unreported mechanistic aspects of the physiopathology of UCMD-derived tendon fibroblasts and point at a role for collagen VI in the modulation of mechanotransduction in tendons.

Aged gastrocnemius muscle of mice positively responds to a late onset adapted physical training

Introduction: A regular physical training is known to contribute to preserve muscle mass and strength, maintaining structure and function of neural and vascular compartments and preventing muscle insulin resistance and inflammation. However, physical activity is progressively reduced during aging causing mobility limitations and poor quality of life. Although physical exercise for rehabilitation purposes (e.g., after fractures or cardiovascular events) or simply aiming to counteract the development of sarcopenia is frequently advised by physicians, nevertheless few data are available on the targets and the global effects on the muscle organ of adapted exercise especially if started at old age. Methods: To contribute answering this question for medical translational purposes, the proteomic profile of the gastrocnemius muscle was analyzed in 24-month-old mice undergoing adapted physical training on a treadmill for 12 weeks or kept under a sedentary lifestyle condition. Proteomic data were implemented by morphological and morphometrical ultrastructural evaluations. Results and Discussion: Data demonstrate that muscles can respond to adapted physical training started at old age, positively modulating their morphology and the proteomic profile fostering protective and saving mechanisms either involving the extracellular compartment as well as muscle cell components and pathways (i.e., mitochondrial processes, cytoplasmic translation pathways, chaperone-dependent protein refolding, regulation of skeletal muscle contraction). Therefore, this study provides important insights on the targets of adapted physical training, which can be regarded as suitable benchmarks for future in vivo studies further exploring the effects of this type of physical activity by functional/metabolic approaches.

Whole exome sequencing identifies a novel variant in the COL12A1 gene in a family with Ullrich congenital muscular dystrophy 2

BACKGROUND

Mutations within the COL12A1 gene have been linked with the onset of congenital Ullrich muscular dystrophy 2 (UCMD2) and Bethlem myopathy. The severity of the symptoms exhibited is dependent on the mutation's type and whether it is heterozygous or homozygous.

METHODS

We used whole-exome sequencing to identify disease-causing variants in a nine-year-old Iranian patient who had weakness, joint contractures, delayed motor development, and other symptoms. We confirmed the pathogenicity of the identified variant using in silico tools and verified its novelty using various databases. We also performed a co-segregation study and confirmed the presence of the variant in the patient's parents by Sanger sequencing.

RESULTS

Our analysis identified a novel homozygous missense variant in the affected patient in COL12A1 (c.8828 C > T; p.Pro2943Leu). This is the second reported family with UCMD2 caused by a mutation in COL12A1. Our findings confirm that this mutation results in significantly more severe symptoms than Bethlem myopathy.

CONCLUSION

Our investigation contributes to the expanding body of evidence that links mutations in COL12A1 with UCMD2. Our findings confirm that the homozygous mutation in COL12A1 caused this condition and suggest that genetic testing for this mutation may be useful for diagnosing patients with this disease.