Post-Translational Modification-Dependent Activity of Matrix Metalloproteinases

The anti-angiogenic and anti-vasculogenic mimicry effects of GN25 in endothelial and glioma cells

BACKGROUND AND PURPOSE

Scientists have been exploring anti-angiogenic strategies to inhibit angiogenesis and prevent tumor growth. Vasculogenic mimicry (VM) in glioblastoma multiforme (GBM) poses a challenge, complicating anti-angiogenesis therapy. A novel drug, GN25 (3-[{1,4-dihydro-5,8-dimethoxy-1,4-dioxo-2-naphthalenyl}thio]-propanoic acid), can inhibit tumor formation. This study aims to investigate the microenvironmental effects and molecular mechanisms of GN25 in anti-angiogenesis and anti-VM.

EXPERIMENTAL APPROACH

MTT (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide) assay was used to evaluate the cell viability of different concentrations of GN25 in human umbilical vein endothelial cells (HUVEC) and Uppsala 87 malignant glioma (U87MG) cells. Functional assays were used to investigate the effects of GN25 on angiogenesis-related processes, whereas gelatin zymography, enzyme-linked immunosorbent assays, and Western blotting were utilized to assess the influence on matrix metalloproteinase (MMP)-2 and vascular endothelial growth factor (VEGF) secretion and related signaling pathways.

KEY RESULTS

GN25 suppressed migration, wound healing, and tube formation in HUVECs and disrupted angiogenesis in a rat aorta ring and zebrafish embryo model. GN25 dose-dependently reduced phosphatidylinositol 3-kinase/AKT and inhibited MMP-2/VEGF secretion in HUVECs. In U87MG cells, GN25 inhibited migration, wound healing, and VM, accompanied by a decrease in MMP-2 and VEGF secretion. The results indicate that GN25 effectively inhibits angiogenesis and VM formation in HUVECs and U87MG cells without affecting preexisting vascular structures.

CONCLUSION AND IMPLICATIONS

This study elaborated GN25's potential as an anti-angiogenic agent by elucidating its inhibitory effects on classical angiogenesis. VM provides valuable insights for developing novel therapeutic strategies against tumor progression and angiogenesis-related diseases. These results indicate the potential of GN25 as a promising candidate for angiogenesis-related diseases.

Functional Analysis of RE1 Silencing Transcription Factor as a Putative Tumor Suppressor in Human Endometrial Cancer

Uterine cancer is the most common gynecologic malignancy in the United States, with endometrioid endometrial adenocarcinoma (EC) being the most common histologic sub-type. Considering the molecular classifications of EC, efforts have been made to identify additional biomarkers that can assist in diagnosis, prognosis, and individualized therapy. We sought to explore the relationship of Repressor Element 1 (RE1) silencing transcription factor (REST), which downregulates neuronal genes in non-neuronal tissue, along with matrix metalloproteinase-24 (MMP24) and EC. We analyzed the expression of REST and MMP24 in 31 cases of endometrial cancer and 16 controls. We then explored the baseline expression of REST and MMP24 in two EC cell lines (Ishikawa and HEC-1-A) compared to a benign cell line (t-HESC) and subsequently evaluated proliferation, migration, and invasion in the setting of loss of REST gene expression. REST and MMP24 expression were significantly lower in human EC samples compared to control samples. REST was highly expressed in EC cell lines, but decreasing REST gene expression increased proliferation (FC: 1.13X, p < 0.0001), migration (1.72X, p < 0.0001), and invasion (FC: 7.77X, p < 0.05) in Ishikawa cells, which are hallmarks of cancer progression and metastasis. These findings elicit a potential role for REST as a putative tumor suppressor in EC.

Selective delivery of imaging probes and therapeutics to the endoplasmic reticulum or Golgi apparatus: Current strategies and beyond

To maximize therapeutic effects and minimize unwanted effects, the interest in drug targeting to the endoplasmic reticulum (ER) or Golgi apparatus (GA) has been recently growing because two organelles are distributing hubs of cellular building/signaling components (e.g., proteins, lipids, Ca2+) to other organelles and the plasma membrane. Their structural or functional damages induce organelle stress (i.e., ER or GA stress), and their aggravation is strongly related to diseases (e.g., cancers, liver diseases, brain diseases). Many efforts have been developed to image (patho)physiological functions (e.g., oxidative stress, protein/lipid-related processing) and characteristics (e.g., pH, temperature, biothiols, reactive oxygen species) in the target organelles and to deliver drugs for organelle disruption using organelle-targeting moieties. Therefore, this review will overview the structure, (patho)physiological functions/characteristics, and related diseases of the organelles of interest. Future direction on ER or GA targeting will be discussed by understanding current strategies and investigations on targeting, imaging/sensing, and therapeutic systems.

Matrix metalloproteinases targeting in prostate cancer

Prostate cancer (PCa) is one of the most common tumors affecting men all over the world. PCa has brought a huge health burden to men around the world, especially for elderly men, but its pathogenesis is unclear. In prostate cancer, epigenetic inheritance plays an important role in the development, progression, and metastasis of the disease. An important role in cancer invasion and metastasis is played by matrix metalloproteinases (MMPs), zinc-dependent proteases that break down extracellular matrix. We review two important forms of epigenetic modification and the role of matrix metalloproteinases in tumor regulation, both of which may be of significant value as novel biomarkers for early diagnosis and prognosis monitoring. The author considers that both mechanisms have promising therapeutic applications for therapeutic agent research in prostate cancer, but that efforts should be made to mitigate or eliminate the side effects of drug therapy in order to maximize quality of life of patients. The understanding of epigenetic modification, MMPs, and their inhibitors in the functional regulation of prostate cancer is gradually advancing, it will provide a new technical means for the prevention of prostate cancer, early diagnosis, androgen-independent prostate cancer treatment, and drug research.

Expression of matrix metalloproteinases and their inhibitors in corneal stromal fibroblasts and keratocytes from healthy and keratoconus corneas

PURPOSE

To examine the in-vitro expression of matrix metalloproteinases (MMP) and tissue inhibitors of metalloproteinases (TIMP) in corneal stromal cells by distinguishing between fibroblasts and keratocytes of healthy and keratoconus (KC) corneas.

METHODS

Stromal cells were isolated from healthy and KC corneas (n = 8). A normal-glucose, serum-containing cell culture medium (NGSC-medium) was used for cultivation of healthy human corneal fibroblasts (HCFs) and KC human corneal fibroblasts (KC-HCFs). In order to obtain a keratocyte phenotype, the initial cultivation with NGSC-medium was changed to a low-glucose, serum-free cell culture medium for healthy (Keratocytes) and KC cells (KC-Keratocytes). Gene and protein expression of MMP-1, -2, -3, -7, -9 and TIMP-1, -2, -3 were measured by quantitative PCR and Enzyme-Linked Immunosorbent Assay (ELISA) from the cell culture supernatant.

RESULTS

KC-HCFs demonstrated a lower mRNA gene expression for MMP-2 compared to HCFs. In contrast to their respective fibroblast groups (either HCFs or KC-HCFs), Keratocytes showed a higher mRNA gene expression of TIMP-3, whereas TIMP-1 mRNA gene expression was lower in Keratocytes and KC-Keratocytes. Protein analysis of the cell culture supernatant revealed lower concentrations of MMP-1 in KC-HCFs compared to HCFs. Compared to Keratocytes, TIMP-1 concentrations was lower in the cell culture supernatant of KC-Keratocytes. In HCFs and KC-HCFs, protein levels of MMP-1 and TIMP-1 were higher and MMP-2 was lower compared to Keratocytes and KC-Keratocytes, respectively.

CONCLUSION

This study indicates an imbalance in MMP and TIMP expression between healthy and diseased cells. Furthermore, differences in the expression of MMPs and TIMPs exist between corneal fibroblasts and keratocytes, which could influence the specific proteolytic metabolism in-vivo and contribute to the progression of KC.

Substrate O-glycosylation actively regulates extracellular proteolysis

Extracellular proteolysis critically regulates cellular and tissue responses and is often dysregulated in human diseases. The crosstalk between proteolytic processing and other major post-translational modifications (PTMs) is emerging as an important regulatory mechanism to modulate protease activity and maintain cellular and tissue homeostasis. Here, we focus on matrix metalloproteinase (MMP)-mediated cleavages and N-acetylgalactosamine (GalNAc)-type of O-glycosylation, two major PTMs of proteins in the extracellular space. We investigated the influence of truncated O-glycan trees, also referred to as Tn antigen, following the inactivation of C1GALT1-specific chaperone 1 (COSMC) on the general and MMP9-specific proteolytic processing in MDA-MB-231 breast cancer cells. Quantitative assessment of the proteome and N-terminome using terminal amine isotopic labelling of substrates (TAILS) technology revealed enhanced proteolysis by MMP9 within the extracellular proteomes of MDA-MB-231 cells expressing Tn antigen. In addition, we detected substantial modifications in the proteome and discovered novel ectodomain shedding events regulated by the truncation of O-glycans. These results highlight the critical role of mature O-glycosylation in fine-tuning proteolytic processing and proteome homeostasis by modulating protein susceptibility to proteolytic degradation. These data suggest a complex interplay between proteolysis and O-GalNAc glycosylation, possibly affecting cancer phenotypes.

Ovarian fibrosis: molecular mechanisms and potential therapeutic targets

Ovarian fibrosis, characterized by the excessive proliferation of ovarian fibroblasts and the accumulation of extracellular matrix (ECM), serves as one of the primary causes of ovarian dysfunction. Despite the critical role of ovarian fibrosis in maintaining the normal physiological function of the mammalian ovaries, research on this condition has been greatly underestimated, which leads to a lack of clinical treatment options for ovarian dysfunction caused by fibrosis. This review synthesizes recent research on the molecular mechanisms of ovarian fibrosis, encompassing TGF-β, extracellular matrix, inflammation, and other profibrotic factors contributing to abnormal ovarian fibrosis. Additionally, we summarize current treatment approaches for ovarian dysfunction targeting ovarian fibrosis, including antifibrotic drugs, stem cell transplantation, and exosomal therapies. The purpose of this review is to summarize the research progress on ovarian fibrosis and to propose potential therapeutic strategies targeting ovarian fibrosis for the treatment of ovarian dysfunction.

Interrogating the Impact of Protease Activity on Tumor Progression Using 3D Spheroid Models

Cancers have a complex relationship with the surrounding environment that regulates everything from progression to response to treatment. Cell-cell and cell-matrix interactions are heavily influenced by protease biology. Studies on the tumor microenvironment have revealed a new complexity for proteases, describing novel substrates for classic proteases, and protease-independent roles for these enzymes. The rapid expansion of 3D in vitro model systems provides excellent tools to study the intricate influence of proteases on the tumor microenvironment. Here we describe a spheroid invasion assay, providing a platform to interrogate key protease-matrix interactions in the context of early-stage breast cancer. Incorporation of pharmacological inhibition and RNAi techniques enables the elucidation of key protease-dependent pathways and can be complemented with immunofluorescence analysis to visualize matrix cleavage events and visualize cell behavior during collective cell invasion.

Mechanistic prospective and pharmacological attributes of quercetin in attenuation of different types of arthritis

Arthritis is a frequent autoimmune disease with undefined etiology and pathogenesis. Scientific community constantly fascinating quercetin (QUR), as it is the best-known flavonoid among others for curative and preventive properties against a wide range of diseases. Due to its multifaceted activities, the implementation of QUR against various types of arthritis namely, rheumatoid arthritis (RA), osteoarthritis (OA), gouty arthritis (GA) and psoriotic arthritis (PsA) has greatly increased in recent years. Many research evidenced that QUR regulates a wide range of pathways for instance NF-κB, MAK, Wnt/β-catenine, Notch, etc., that are majorly associated with the inflammatory mechanisms. Besides, the bioavailability of QUR is a major constrain to its therapeutic potential, and drug delivery techniques have experienced significant development to overcome the problem of its limited application. Hence, this review compiled the cutting-edge experiments on versatile effects of QUR on inflammatory diseases like RA, OA, GA and PsA, sources and bioavailability, therapeutic challenges, pharmacokinetics, clinical studies as well as toxicological impacts. The use of QUR in a health context would offer a tearing and potential therapeutic method, supporting the advancement of public health, particularly, of arthritic patients worldwide.

The role of matrix metalloproteinases in infectious corneal ulcers

During infectious keratitis, the production of collagenolytic and inflammatory substances, along with increased corneal matrix metalloproteinase (MMP) activity, induces the degradation of corneal collagen and may cause postkeratitis complications, such as opacity, thinning, and corneal perforation. MMPs, especially MMP-2 and MMP-9, are overexpressed in infectious keratitis and sustained over time by inflammatory and nonmicrobial mechanisms. The high MMP levels are correlated with excessive corneal destruction in bacterial, herpetic, fungal, and acanthamoeba infections. Nonspecific treatments, such as tetracyclines, particularly doxycycline, or corticosteroids, are used as adjuvants to antimicrobials to alleviate the disproportionate degradation and inflammation of the corneal layers caused by corneal MMPs and decrease the recruitment and infiltration of inflammatory cells. Treatments showing inhibition of specific MMPs (Galardin, ZHAWOC7726), interfering with pro-MMP activation (EDTA, ascorbic acid), or showing anticytokine effect (epigallocatechin-2-gallate, TRAM-34) have been reported. Other treatments show a direct action over corneal collagen structure such as corneal cross-linking or have been associated with reduction of MMP levels such as amniotic membrane grafting. Although the use of these drugs has been shown in studies to be effective in controlling inflammation, especially in experimental ones, robust studies are still needed based on randomized and randomized clinical trials to demonstrate their potential effect as adjuvants in the management of infectious keratitis.

ADAMTS3 restricts cancer invasion in models of early breast cancer progression through enhanced fibronectin degradation

Proteases have long been associated with cancer progression, due to their ability to facilitate invasion upon matrix remodelling. However, proteases are not simply degraders of the matrix, but also play fundamental roles in modulating cellular behaviour through the proteolytic processing of specific substrates. Indeed, proteases can elicit both pro- and anti- tumorigenic effects depending on context. Using a heterocellular spheroid model of breast cancer progression, we demonstrate the repressive function of myoepithelial ADAMTS3, with its loss directing myoepithelial-led invasion of luminal cells through a physiologically relevant matrix. Degradomic analysis, using terminal amine isotopic labelling of substrates (TAILS), combined with functional assays, implicate ADAMTS3 as a mediator of fibronectin degradation. We show further that loss of ADAMTS3 enhances levels of fibronectin in the microenvironment, promoting invasion through canonical integrin α5β1 activation. Our data highlight a tumour suppressive role for ADAMTS3 in early stage breast cancer, and contribute to the growing evidence that proteases can restrain cancer progression.

Degradomic Identification of Membrane Type 1-Matrix Metalloproteinase as an ADAMTS9 and ADAMTS20 Substrate

The secreted metalloproteases ADAMTS9 and ADAMTS20 are implicated in extracellular matrix proteolysis and primary cilium biogenesis. Here, we show that clonal gene-edited RPE-1 cells in which ADAMTS9 was inactivated, and which constitutively lack ADAMTS20 expression, have morphologic characteristics distinct from parental RPE-1 cells. To investigate underlying proteolytic mechanisms, a quantitative terminomics method, terminal amine isotopic labeling of substrates was used to compare the parental and gene-edited RPE-1 cells and their medium to identify ADAMTS9 substrates. Among differentially abundant neo-amino (N) terminal peptides arising from secreted and transmembrane proteins, a peptide with lower abundance in the medium of gene-edited cells suggested cleavage at the Tyr314-Gly315 bond in the ectodomain of the transmembrane metalloprotease membrane type 1-matrix metalloproteinase (MT1-MMP), whose mRNA was also reduced in gene-edited cells. This cleavage, occurring in the MT1-MMP hinge, that is, between the catalytic and hemopexin domains, was orthogonally validated both by lack of an MT1-MMP catalytic domain fragment in the medium of gene-edited cells and restoration of its release from the cell surface by reexpression of ADAMTS9 and ADAMTS20 and was dependent on hinge O-glycosylation. A C-terminally semitryptic MT1-MMP peptide with greater abundance in WT RPE-1 medium identified a second ADAMTS9 cleavage site in the MT1-MMP hemopexin domain. Consistent with greater retention of MT1-MMP on the surface of gene-edited cells, pro-MMP2 activation, which requires cell surface MT1-MMP, was increased. MT1-MMP knockdown in gene-edited ADAMTS9/20-deficient cells restored focal adhesions but not ciliogenesis. The findings expand the web of interacting proteases at the cell surface, suggest a role for ADAMTS9 and ADAMTS20 in regulating cell surface activity of MT1-MMP, and indicate that MT1-MMP shedding does not underlie their observed requirement in ciliogenesis.

Insights into the effect of protein glycosylation on carbohydrate substrate binding

The role of glycosylation in the binding of glycoproteins to carbohydrate substrates has not been well understood. The present study addresses this knowledge gap by elucidating the links between the glycosylation patterns of a model glycoprotein, a Family 1 carbohydrate-binding module (TrCBM1), and the thermodynamic and structural properties of its binding to different carbohydrate substrates using isothermal titration calorimetry and computational simulation. The variations in glycosylation patterns cause a gradual transition of the binding to soluble cellohexaose from an entropy-driven process to an enthalpy-driven one, a trend closely correlated with the glycan-induced shift of the predominant binding force from hydrophobic interactions to hydrogen bonding. However, when binding to a large surface of solid cellulose, glycans on TrCBM1 have a more dispersed distribution and thus have less adverse impact on the hydrophobic interaction forces, leading to overall improved binding. Unexpectedly, our simulation results also suggest an evolutionary role of O-mannosylation in transforming the substrate binding features of TrCBM1 from those of type A CBMs to those of type B CBMs. Taken together, these findings provide new fundamental insights into the molecular basis of the role of glycosylation in protein-carbohydrate interactions and are expected to better facilitate further studies in this area.

Matrix Metalloproteinases in Chronic Obstructive Pulmonary Disease

Matrix metalloproteinases (MMPs) are proteolytic enzymes that degrade proteins of the extracellular matrix and the basement membrane. Thus, these enzymes regulate airway remodeling, which is a major pathological feature of chronic obstructive pulmonary disease (COPD). Furthermore, proteolytic destruction in the lungs may lead to loss of elastin and the development of emphysema, which is associated with poor lung function in COPD patients. In this literature review, we describe and appraise evidence from the recent literature regarding the role of different MMPs in COPD, as well as how their activity is regulated by specific tissue inhibitors. Considering the importance of MMPs in COPD pathogenesis, we also discuss MMPs as potential targets for therapeutic intervention in COPD and present evidence from recent clinical trials in this regard.

13‑cis‑retinoic acid inhibits the self‑renewal, migration, invasion and adhesion of cholangiocarcinoma cells

13‑cis‑retinoic acid (13CRA), a Food and Drug Administration‑approved drug for severe acne, is currently being investigated for its potential use in skin cancer prevention. 13CRA has been reported to exhibit antitumor effects against various types of cancer cells, both in vitro and in vivo. However, to the best of our knowledge, no information is yet available regarding the effects of 13CRA on cholangiocarcinoma (CCA), a malignancy of the bile duct epithelia. Currently, there are no reliably effective therapeutic options for metastatic CCA. The present study thus aimed to evaluate the effects of 13CRA on the self‑renewal, migration, invasion and adhesion of CCA cells, and also investigated the underlying mechanisms. The results revealed that 13CRA suppressed cell proliferation via the inhibition of the self‑renewal ability of CCA cells. 13CRA induced cell cycle arrest at the G₂/M phase in KKU‑100 and KKU‑213B CCA cells through the regulation of cell cycle‑regulatory genes and proteins. 13CRA reduced the cell migratory ability of both cell lines via the modulation of the genes and proteins associated with epithelial‑mesenchymal transition. 13CRA also inhibited the invasive and adhesive abilities of CCA cells via the suppression of genes and proteins associated with the invasion and adhesion of CCA cells. On the whole, these results suggested that 13CRA exerts suppressive effects on CCA cell proliferation, migration, adhesion and invasion.

The immunomodulatory role of matrix metalloproteinases in colitis-associated cancer

Matrix metalloproteinases (MMPs) are an important class of enzymes in the body that function through the extracellular matrix (ECM). They are involved in diverse pathophysiological processes, such as tumor invasion and metastasis, cardiovascular diseases, arthritis, periodontal disease, osteogenesis imperfecta, and diseases of the central nervous system. MMPs participate in the occurrence and development of numerous cancers and are closely related to immunity. In the present study, we review the immunomodulatory role of MMPs in colitis-associated cancer (CAC) and discuss relevant clinical applications. We analyze more than 300 pharmacological studies retrieved from PubMed and the Web of Science, related to MMPs, cancer, colitis, CAC, and immunomodulation. Key MMPs that interfere with pathological processes in CAC such as MMP-2, MMP-3, MMP-7, MMP-9, MMP-10, MMP-12, and MMP-13, as well as their corresponding mechanisms are elaborated. MMPs are involved in cell proliferation, cell differentiation, angiogenesis, ECM remodeling, and the inflammatory response in CAC. They also affect the immune system by modulating differentiation and immune activity of immune cells, recruitment of macrophages, and recruitment of neutrophils. Herein we describe the immunomodulatory role of MMPs in CAC to facilitate treatment of this special type of colon cancer, which is preceded by detectable inflammatory bowel disease in clinical populations.

Degradomics technologies in matrisome exploration

Consisting of a defined set of extracellular proteins secreted from resident cells and with minor contributions from serum proteins, the extracellular matrix (ECM) is an essential component of all tissues. Maintaining tissue homeostasis, structural support and cellular control through cell-ECM communication, the ECM has come to be viewed as not just a passive structural entity but rather as a dynamic signaling conduit between cells and the extracellular compartment. Proteins and their cleavage products mediate this communication, and aberrant signaling, either directly or indirectly distorting the ECM, results in pathological conditions including cancer, inflammation, fibrosis, and neurodegenerative diseases. Characterization of ECM components, the matrisome, the extracellular environment and their changes in disease is therefore of importance to understand and mitigate by developing novel therapeutics. Liquid chromatography-mass spectrometry (LC-MS) proteomics has been integral to protein and proteome research for decades and long superseded the obsolescent gel-based approaches. A continuous effort has ensured progress with increased sensitivity and throughput as more advanced equipment has been developed hand in hand with specialized enrichment, detection, and identification methods. Part of this effort lies in the field of degradomics, a branch of proteomics focused on discovering novel protease substrates by identification of protease-generated neo-N termini, the N-terminome, and characterizing the responsible protease networks. Various methods to do so have been developed, some specialized for specific tissue types, others for particular proteases, throughput, or ease of use. This review aims to provide an overview of the state-of-the-art proteomics techniques that have successfully been recently utilized to characterize proteolytic cleavages in the ECM and thereby guided new research and understanding of the ECM and matrisome biology.

N-Linked Glycosylation in Chinese Hamster Ovary Cells Is Critical for Insulin-like Growth Factor 1 Signaling

Cell surface proteins carrying N-glycans play important roles in inter- and intracellular processes including cell adhesion, development, and cellular recognition. Dysregulation of the glycosylation machinery has been implicated in various diseases, and investigation of global differential cell surface proteome effects due to the loss of N-glycosylation will provide comprehensive insights into their pathogenesis. Cell surface proteins isolated from Parent Pro^-5 CHO cells (W5 cells), two CHO mutants with loss of N-glycosylation function derived from Pro^-5 CHO (Lec1 and Lec4 cells), were subjected to proteome analysis via high-resolution LCMS. We identified 44 and 43 differentially expressed membrane proteins in Lec1 and Lec4 cells, respectively, as compared to W5 cells. The defective N-glycosylation mutants showed increased abundance of integrin subunits in Lec1 and Lec4 cells at the cell surface. We also found significantly reduced levels of IGF-1R (Insulin like growth factor-1 receptor); a receptor tyrosine kinase; and the GTPase activating protein IQGAP1 (IQ motif-containing GTPase activating protein), a highly conserved cytoplasmic scaffold protein) in Lec1 and Lec4 cells. In silico docking studies showed that the IQ domain of IQGAP1 interacts with the kinase domain of IGF-1R. The integrin signaling and insulin growth factor receptor signaling were also enriched according to GSEA analysis and pathway analysis of differentially expressed proteins. Significant reductions of phosphorylation of ERK1 and ERK2 in Lec1 and Lec4 cells were observed upon IGF-1R ligand (IGF-1 LR3) stimulation. IGF-1 LR3, known as Long arginine3-IGF-1, is a synthetic protein and lengthened analog of insulin-like growth factor 1. The work suggests a novel mechanism for the activation of IGF-1 dependent ERK signaling in CHO cells, wherein IQGAP1 plausibly functions as an IGF-1R-associated scaffold protein. Appropriate glycosylation by the enzymes MGAT1 and MGAT5 is thus essential for processing of cell surface receptor IGF-1R, a potential binding partner in IQGAP1 and ERK signaling, the integral components of the IGF pathway.

Role of Matrix Metalloproteinases in Musculoskeletal Diseases

Musculoskeletal disorders include rheumatoid arthritis, osteoarthritis, sarcopenia, injury, stiffness, and bone loss. The prevalence of these conditions is frequent among elderly populations with significant mobility and mortality rates. This may lead to extreme discomfort and detrimental effect on the patient’s health and socioeconomic situation. Muscles, ligaments, tendons, and soft tissue are vital for body function and movement. Matrix metalloproteinases (MMPs) are regulatory proteases involved in synthesizing, degrading, and remodeling extracellular matrix (ECM) components. By modulating ECM reconstruction, cellular migration, and differentiation, MMPs preserve myofiber integrity and homeostasis. In this review, the role of MMPs in skeletal muscle function, muscle injury and repair, skeletal muscle inflammation, and muscular dystrophy and future approaches for MMP-based therapies in musculoskeletal disorders are discussed at the cellular and molecule level.

Novel Roles of MT1-MMP and MMP-2: Beyond the Extracellular Milieu

Matrix metalloproteinases (MMPs) are critical enzymes involved in a variety of cellular processes. MMPs are well known for their ability to degrade the extracellular matrix (ECM) and their extracellular role in cell migration. Recently, more research has been conducted on investigating novel subcellular localizations of MMPs and their intracellular roles at their respective locations. In this review article, we focus on the subcellular localization and novel intracellular roles of two closely related MMPs: membrane-type-1 matrix metalloproteinase (MT1-MMP) and matrix metalloproteinase-2 (MMP-2). Although MT1-MMP is commonly known to localize on the cell surface, the protease also localizes to the cytoplasm, caveolae, Golgi, cytoskeleton, centrosome, and nucleus. At these subcellular locations, MT1-MMP functions in cell migration, macrophage metabolism, invadopodia development, spindle formation and gene expression, respectively. Similar to MT1-MMP, MMP-2 localizes to the caveolae, mitochondria, cytoskeleton, nucleus and nucleolus and functions in calcium regulation, contractile dysfunction, gene expression and ribosomal RNA transcription. Our particular interest lies in the roles MMP-2 and MT1-MMP serve within the nucleus, as they may provide critical insights into cancer epigenetics and tumor migration and invasion. We suggest that targeting nuclear MT1-MMP or MMP-2 to reduce or halt cell proliferation and migration may lead to the development of new therapies for cancer and other diseases.

Alpha synuclein processing by MMP-3 - implications for synucleinopathies

α-Synuclein (aSyn) is a protein implicated in physiological functions such as neurotransmitter release at the synapse and the regulation of gene expression in the nucleus. In addition, pathological aSyn assemblies are characteristic for a class of protein aggregation disorders referred to as synucleinopathies, where aSyn aggregates appear as Lewy bodies and Lewy neurites. We recently discovered a novel post-translational pyroglutamate (pGlu) modification at Gln79 of N-truncated aSyn that promotes oligomer formation and neurotoxicity in human synucleinopathies. A priori, the appearance of pGlu79-aSyn in vivo involves a two-step process of free N-terminal Gln79 residue generation and subsequent cyclization of Gln79 into pGlu79. Prime candidate enzymes for these processes are matrix metalloproteinase-3 (MMP-3) and glutaminyl cyclase (QC). Here, we analyzed the expression of aSyn, MMP-3, QC and pGlu79-aSyn in brains of two transgenic mouse models for synucleinopathies (BAC-SNCA and ASO) by triple immunofluorescent labellings and confocal laser scanning microscopy. We report a co-localization of these proteins in brain structures typically affected by aSyn pathology, namely hippocampus in BAC-SNCA mice and substantia nigra in ASO mice. In addition, Western blot analyses revealed a high abundance of QC, MMP-3 and transgenic human aSyn in brain stem and thalamus but lower levels in cortex/hippocampus, whereas endogenous mouse aSyn was found to be most abundant in cortex/hippocampus, followed by thalamus and brain stem. During aging of ASO mice, we observed no differences between controls and transgenic mice in MMP-3 levels but higher QC content in thalamus of 6-month-old transgenic mice. Transgenic human aSyn abundance transiently increased and then showed decrease in oldest ASO mice analyzed. Immunohistochemistry revealed a successive increase in intraneuronal and extracellular formation of pGlu79-aSyn in substantia nigra during aging of ASO mice. Together, our data are supportive for a role of MMP-3 and QC in the generation of pGlu79-aSyn in brains affected by aSyn pathology.

Immunohistochemical Demonstration of the pGlu79 α-Synuclein Fragment in Alzheimer’s Disease and Its Tg2576 Mouse Model

The deposition of β-amyloid peptides and of α-synuclein proteins is a neuropathological hallmark in the brains of Alzheimer’s disease (AD) and Parkinson’s disease (PD) subjects, respectively. However, there is accumulative evidence that both proteins are not exclusive for their clinical entity but instead co-exist and interact with each other. Here, we investigated the presence of a newly identified, pyroglutamate79-modified α-synuclein variant (pGlu79-aSyn)—along with the enzyme matrix metalloproteinase-3 (MMP-3) and glutaminyl cyclase (QC) implicated in its formation—in AD and in the transgenic Tg2576 AD mouse model. In the human brain, pGlu79-aSyn was detected in cortical pyramidal neurons, with more distinct labeling in AD compared to control brain tissue. Using immunohistochemical double and triple labelings and confocal laser scanning microscopy, we demonstrate an association of pGlu79-aSyn, MMP-3 and QC with β-amyloid plaques. In addition, pGlu79-aSyn and QC were present in amyloid plaque-associated reactive astrocytes that were also immunoreactive for the chaperone heat shock protein 27 (HSP27). Our data are consistent for the transgenic mouse model and the human clinical condition. We conclude that pGlu79-aSyn can be generated extracellularly or within reactive astrocytes, accumulates in proximity to β-amyloid plaques and induces an astrocytic protein unfolding mechanism involving HSP27.

Matrix Metalloproteinases: From Molecular Mechanisms to Physiology, Pathophysiology, and Pharmacology

The first matrix metalloproteinase (MMP) was discovered in 1962 from the tail of a tadpole by its ability to degrade collagen. As their name suggests, matrix metalloproteinases are proteases capable of remodeling the extracellular matrix. More recently, MMPs have been demonstrated to play numerous additional biologic roles in cell signaling, immune regulation, and transcriptional control, all of which are unrelated to the degradation of the extracellular matrix. In this review, we will present milestones and major discoveries of MMP research, including various clinical trials for the use of MMP inhibitors. We will discuss the reasons behind the failures of most MMP inhibitors for the treatment of cancer and inflammatory diseases. There are still misconceptions about the pathophysiological roles of MMPs and the best strategies to inhibit their detrimental functions. This review aims to discuss MMPs in preclinical models and human pathologies. We will discuss new biochemical tools to track their proteolytic activity in vivo and ex vivo, in addition to future pharmacological alternatives to inhibit their detrimental functions in diseases. SIGNIFICANCE STATEMENT: Matrix metalloproteinases (MMPs) have been implicated in most inflammatory, autoimmune, cancers, and pathogen-mediated diseases. Initially overlooked, MMP contributions can be both beneficial and detrimental in disease progression and resolution. Thousands of MMP substrates have been suggested, and a few hundred have been validated. After more than 60 years of MMP research, there remain intriguing enigmas to solve regarding their biological functions in diseases.

Protease production and molecular characterization of a protease dipeptidyl-aminopeptidase gene from different strains of Sordaria fimicola

The current research was designed to reach extracellular protease production potential in different strains of Sordaria fimicola which were previously obtained from Dr. Lamb (Imperial College, London) from North Facing Slope and South Facing Slope of Evolution Canyon. After initial and secondary screening, two hyper-producers strains S2 and N6 were selected for submerged fermentation and cultural conditions including temperature, pH, incubation period, inoculum size, substrate concentration, and different carbon and nitrogen sources were optimized for enzyme production. S2 strain showed maximum protease production of 3.291 U/mL after 14 days of incubation at 30 °C with 7 pH, 1% substrate concentration and 1 mL inoculum, While N6 strain showed maximum protease production of 1.929 U/mL under fermentation optimized conditions. Another aim of the present research was to underpin the biodiversity of genetics and post-translational modifications (PTMs) of protease DPAP (peptidyl-aminopeptidase) in Sordaria fimicola. Five polymorphic sites were observed in amino acid sequence of S. fimicola strains with reference to Neurospora crassa. PTMs prediction from bioinformatics tools predicted 38 phosphorylation sites on serine residues for protease peptidyl-aminopeptidase in S1 strain of S. fimicola while 45 phosphorylation sites on serine in N7 strain and 47 serine phosphorylation modifications were predicted in N. crassa. Current research gave an insight that change in genetic makeup effected PTMs which ultimately affected the production of protease enzyme in different strains of same organism (S. fimicola). The production and molecular data of the research revealed that environmental stress has strong effects on the specific genes through mutations which may cause genetic diversity. S. fimicola is non- pathogenic fungus and has a short life cycle. This fungus can be chosen to produce protease enzyme on a commercial scale.

Altered gene expression of selected matrix metalloproteinase system proteins in the broiler chicken gastrointestinal tract during post-hatch development and coccidia infection*

Matrix metalloproteinases (MMPs) are a family of proteases, that can process extracellular matrix (ECM) components and non-ECM molecules. MMPs can also function intracellularly in proteolytic and nonproteolytic functions. The participation of MMPs in the remodeling of the chicken gastrointestinal tract is largely unknown. The aim of the present study was to examine 1) the early neonatal developmental changes and effect of delayed access to feed immediately post-hatch (PH) and 2) the effect of Eimeria infection on mRNA expression of selected MMPs, their tissue inhibitors (TIMPs), and a disintegrin and metalloproteinase (ADAM) metallopeptidase with thrombospondin type 1 motif 8 (ADAMTS8) in the gastrointestinal tract of chicken. Protein localization of MMPs and TIMPs was also carried out in the normal ileal wall at −48, 24, and 336 h relative to hatch using immunofluorescence. In experiment 1, newly hatched Ross 708 chicks received feed and water immediately PH or were subjected to 48 h delayed access to feed. Chickens were sampled at −48, 0, 4, 24, 48, 72, 96, 144, 192, 240, 288, and 336 h PH. Ileum was collected for investigation of gene expression or fixed in paraformaldehyde for immunofluorescence. In experiments 2 and 3, Ross 708 male broilers were infected, at 21 d of age with Eimeria maxima or E. acervulina or sham-infected with water. Intestinal tissues were collected at 7 and 10 d postinfection for gene expression analysis. In general, mRNA expression patterns of all examined genes showed downregulation during the first 2 wk PH and were not affected by delay in feed access. These development-dependent changes in expression and tissue-dependent localization in the ileum of selected MMPs and TIMPs indicate that these molecules participate in the remodeling of chicken intestinal tissues during PH development. Increased expression of MMP-7 and MMP-9 transcripts in the intestine of Eimeria infected birds suggests an important role for these enzymes in the process of tissue remodeling and destruction in pathological conditions. The findings of this study are important for understanding the relationship between the expression of the MMP system and intestinal development, as well its role in gastrointestinal infection and subsequent recovery.

Genetic Variants of Matrix Metalloproteinase and Sepsis: The Need Speed Study

Many causal mechanisms in sepsis susceptibility are largely unknown and the functional genetic polymorphisms (GP) of matrix metalloproteinases (MMPs) and their natural tissue inhibitor of MMPs (TIMP1) could play a role in its development. GPs of MMPs and TIMP (namely MMP-1 rs1799750, MMP-3 rs3025058, MMP-8 rs11225395, MMP-9 rs2234681, and TIMP-1 rs4898) have been compared in 1058 patients with suspected sepsis to assess the association with susceptibility and etiology of sepsis. Prevalence of MMP8 rs11225395 G/G genotype was higher in sepsis patients than in those with non-infective Systemic Inflammatory Reaction Syndrome (35.6 vs. 26%, hazard ratio, HR 1.56, 95% C.I. 1.04–2.42, p = 0.032). G/G patients developed less hyperthermia (p = 0.041), even after stratification for disease severity (p = 0.003). Patients carrying the 6A allele in MMP3 rs3025058 had a higher probability of microbiologically-proven sepsis (HR 1.4. 95%C.I. 1.01–1.94, p = 0.044), particularly when due to virus (H.R. 2.14, 95% C.I. 1.06–4.31, p = 0.046), while MMP-1 G/G genotype patients carried a higher risk for intracellular bacteria (Chlamydia, Mycoplasma, and Legionella, H.R. 6.46, 95% C.I. 1.58–26.41, p = 0.003). Neither severity of sepsis at presentation, nor 30-day mortality were influenced by the investigated variants or their haplotype. MMP8 rs11225395 G/G carriers have lower temperature at presentation and a more than 50% increased susceptibility to sepsis. Among patients with sepsis, carriers of MMP1 rs1799750 G/G have an increased susceptibility for intracellular pathogen infections, while virus serology is more often positive in those with the MMP3 rs3025058 A/A genotype.

Matrix Metalloproteinases in Helicobacter pylori-Associated Gastritis and Gastric Cancer

Gastric cancer is one of the leading causes of the cancer-related mortality worldwide. The etiology of this disease is complex and involves genetic predisposition and environmental factors, including Helicobacter pylori. Infection of the stomach with H. pylori leads to gastritis and gastric atrophy, which can progress stepwise to gastric cancer. Matrix metalloproteinases (MMPs) actively participate in the pathology development. The further progression of gastric cancer seems to be less dependent on bacteria but of intra-tumor cell dynamics. Bioinformatics data confirmed an important role of the extracellular matrix constituents and specific MMPs in stomach carcinoma invasion and metastasis, and revised their potential as predictors of the disease outcome. In this review, we describe, in detail, the impact of MMPs in H. pylori-associated gastritis and gastric cancer.

Polybrominated diphenyl ethers BDE-47 and BDE-99 modulate murine melanoma cell phenotype in vitro

Cancer is one of the leading causes of mortality worldwide. Even with the advances of pharmaceutical industry and treatments, the mortality rate for various types of cancer remains high. In particular, phenotypic alterations of tumor cells concerning drug efflux, migratory and invasive capabilities may represent a hurdle for cancer treatment and contribute to poor prognosis. In the present study, we investigated the effects of polybrominated diphenyl ethers (PBDEs) used as flame retardants on phenotypic features of melanoma cells that are important for cancer. Murine melanoma B16-F1 (less metastatic) and B16-F10 (more metastatic) cells were exposed to 0.01-1.0 nM of BDE-47 (2,2',4,4'-tetrabromodiphenyl ether), BDE-99 (2,2',4,4',5-pentabromodiphenyl ether), and the mixture of both (at 0.01 nM) for 24 h (acute exposure) and 15 days (chronic exposure). The polybrominated diphenyl ethers (PBDEs) did not affect cell viability but led to increased drug efflux transporter activity, cell migration, and colony formation, as well as overexpression of Abcc2 (ATP-binding cassette subfamily C member 2), Mmp-2 (matrix metalloproteinase-2), Mmp-9 (matrix metalloproteinase-9), and Tp53 (tumor protein p53) genes and downregulation of Timp-3 (tissue inhibitor of metalloproteinase 3) gene in B16-F10 cells. These effects are consistent with increased aggressiveness and malignancy of tumors due to exposure to the flame retardants and raise some concerns on the effects such chemicals may have on melanoma treatment and cancer prognosis.

Adaptation of the Golgi Apparatus in Cancer Cell Invasion and Metastasis

The Golgi apparatus plays a central role in normal cell physiology by promoting cell survival, facilitating proliferation, and enabling cell-cell communication and migration. These roles are partially mediated by well-known Golgi functions, including post-translational modifications, lipid biosynthesis, intracellular trafficking, and protein secretion. In addition, accumulating evidence indicates that the Golgi plays a critical role in sensing and integrating external and internal cues to promote cellular homeostasis. Indeed, the unique structure of the mammalian Golgi can be fine-tuned to adapt different Golgi functions to specific cellular needs. This is particularly relevant in the context of cancer, where unrestrained proliferation and aberrant survival and migration increase the demands in Golgi functions, as well as the need for Golgi-dependent sensing and adaptation to intrinsic and extrinsic stressors. Here, we review and discuss current understanding of how the structure and function of the Golgi apparatus is influenced by oncogenic transformation, and how this adaptation may facilitate cancer cell invasion and metastasis.

Unveiling a Hidden Biomarker of Inflammation and Tumor Progression: The 65 kDa Isoform of MMP-9 New Horizons for Therapy

Cancer metastasis is a stage of the disease where therapy is mostly ineffective; hence, the need to find reliable markers of its onset. The metalloproteinase-9 (MMP-9, gelatinase B) in its 82 kDa active form, is a good candidate, but here we show that the correspondent little known 65 kDa active MMP-9 isoform, often misrepresented with the other gelatinase MMP-2, is a more suitable marker. Sera from patients with lung and breast cancer were analyzed by bidimensional zymography to detect the activity of MMP-9 and MMP-2. Enzyme identity was confirmed by comparison with MMP-9 standards and by western blotting. The 65 kDa isoform of MMP-9 is a suitable biomarker to monitor tumor progression from tissue neoplasms to metastatic stage, as its activity begins to appear when disease severity increases and becomes very high in metastasis. Moreover, the 65 kDa MMP-9, which derives from the 82 kDa MMP-9, no longer responds to natural MMP-9 inhibitors. As its activity cannot be controlled, its appearance may warn that the pathological process is becoming irreversible. Identification and inhibition of the enzymes converting the inhibitor-sensitive 82 kDa MMP-9 into the corresponding “wild” 65 kDa MMP-9 may allow to develop therapies capable of blocking metastases.

Pro-angiogenic activity and vasculogenic mimicry in the tumor microenvironment by leptin in cancer

The acquired ability to induce the formation of a functional vasculature is a hallmark of cancer. Blood vessels in tumors are formed through various mechanisms, among the most important in cancer biology, angiogenesis, and vasculogenic mimicry have been described. Leptin is one of the main adipokines secreted by adipocytes in normal breast tissue and the tumor microenvironment. Here, we provide information on the relationship between leptin and the development of angiogenesis and vasculogenic mimicry in different types of cancer. Here, we report that leptin activates different pathways such as JAK-STAT3, MAPK/ERK, PKC, JNK, p38, and PI3K-Akt to induce the expression of various angiogenic factors and vasculogenic mimicry. In vivo models, leptin induces blood vessel formation through the PI3K-Akt-mTOR pathway. Interestingly, the relationship between leptin and vasculogenic mimicry was more significant in breast cancer. The information obtained suggests that leptin could be playing an essential role in tumor survival and metastasis through the induction of vascular mechanisms such as angiogenesis and vasculogenic mimicry; thus, leptin-induced pathways could be suggested as a promising therapeutic target.

Nicotinamide N-Methyltransferase: An Emerging Protagonist in Cancer Macro(r)evolution

Nicotinamide N-methyltransferase (NNMT) has progressed from being considered merely a Phase II metabolic enzyme to one with a central role in cell function and energy metabolism. Over the last three decades, a significant body of evidence has accumulated which clearly demonstrates a central role for NNMT in cancer survival, metastasis, and drug resistance. In this review, we discuss the evidence supporting a role for NNMT in the progression of the cancer phenotype and how it achieves this by driving the activity of pro-oncogenic NAD+-consuming enzymes. We also describe how increased NNMT activity supports the Warburg effect and how it promotes oncogenic changes in gene expression. We discuss the regulation of NNMT activity in cancer cells by both post-translational modification of the enzyme and transcription factor binding to the NNMT gene, and describe for the first time three long non-coding RNAs which may play a role in the regulation of NNMT transcription. We complete the review by discussing the development of novel anti-cancer therapeutics which target NNMT and provide insight into how NNMT-based therapies may be best employed clinically.

Matrix Metalloproteinases (MMPs) and Inhibitors of MMPs in the Avian Reproductive System: An Overview

Many matrix metalloproteinases (MMPs) are produced in the mammalian reproductive system and participate in the regulation of its functions. In birds, the limited information available thus far indicates that MMPs are significant regulators of avian ovarian and oviductal functions, too. Some MMPs and inhibitors of MMPs are present in the hen reproductive tissues and their abundances and/or activities change according to the physiological state. The intraovarian role of MMPs likely includes the remodeling of the extracellular matrix (ECM) during folliculogenesis, follicle atresia, and postovulatory regression. In the oviduct, MMPs are also involved in ECM turnover during oviduct development and regression. This study provides a review of the current knowledge on the presence, activity, and regulation of MMPs in the female reproductive system of birds.

Collagenase and Tyrosinase Inhibitory Effect of Isolated Constituents from the Moss Polytrichum formosum

Mosses from the genus Polytrichum have been shown to contain rare benzonaphthoxanthenones compounds, and many of these have been reported to have important biological activities. In this study, extracts from Polytrichum formosum were analyzed in vitro for their inhibitory properties on collagenase and tyrosinase activity, two important cosmetic target enzymes involved respectively in skin aging and pigmentation. The 70% ethanol extract showed a dose-dependent inhibitory effect against collagenase (IC₅₀ = 4.65 mg/mL). The methanol extract showed a mild inhibitory effect of 44% against tyrosinase at 5.33 mg/mL. Both extracts were investigated to find the constituents having a specific affinity to the enzyme targets collagenase and tyrosinase. The known compounds ohioensin A (1), ohioensin C (3), and communin B (4), together with nor-ohioensin D (2), a new benzonaphthoxanthenone, were isolated from P. formosum. Their structures were determined by mass spectrometry and NMR spectroscopy. Compounds 1 (IC₅₀ = 71.99 µM) and 2 (IC₅₀ = 167.33 µM) showed inhibitory activity against collagenase. Compound 1 also exhibited inhibition of 30% against tyrosinase activity at 200 µM. The binding mode of the active compounds was theoretically generated by an in-silico approach against the 3D structures of collagenase and tyrosinase. These current results present the potential application from the moss P. formosum as a new natural source of collagenase and tyrosinase inhibitors.

Current Perspectives on the Role of Matrix Metalloproteinases in the Pathogenesis of Basal Cell Carcinoma

Basal cell carcinoma (BCC) is the most common skin malignancy, which rarely metastasizes but has a great ability to infiltrate and invade the surrounding tissues. One of the molecular players involved in the metastatic process are matrix metalloproteinases (MMPs). MMPs are enzymes that can degrade various components of the extracellular matrix. In the skin, the expression of MMPs is increased in response to various stimuli, including ultraviolet (UV) radiation, one of the main factors involved in the development of BCC. By modulating various processes that are linked to tumor growth, such as invasion and angiogenesis, MMPs have been associated with UV-related carcinogenesis. The sources of MMPs are multiple, as they can be released by both neoplastic and tumor microenvironment cells. Inhibiting the action of MMPs could be a useful therapeutic option in BCC management. In this review that reunites the latest advances in this domain, we discuss the role of MMPs in the pathogenesis and evolution of BCC, as molecules involved in tumor aggressiveness and risk of recurrence, in order to offer a fresh and updated perspective on this field.

3D Spheroids Versus 3D Tumor-Like Microcapsules: Confinement and Mechanical Stress May Lead to the Expression of Malignant Responses in Cancer Cells

As 2D surfaces fail to resemble the tumoral milieu, current discussions are focused on which 3D cell culture strategy may better lead the cells to express in vitro most of the malignant hints described in vivo. In this study, this question is assessed by analyzing the full genetic profile of MCF7 cells cultured either as 3D spheroids-considered as "gold standard" for in vitro cancer research- or immobilized in 3D tumor-like microcapsules, by RNA-Seq and transcriptomic methods, allowing to discriminate at big-data scale, which in vitro strategy can better resemble most of the malignant features described in neoplastic diseases. The results clearly show that mechanical stress, rather than 3D morphology only, stimulates most of the biological processes involved in cancer pathogenicity, such as cytoskeletal organization, migration, and stemness. Furthermore, cells entrapped in hydrogel-based scaffolds are likely expressing other physiological hints described in malignancy, such as the upregulated expression of metalloproteinases or the resistance to anticancer drugs, among others. According to the knowledge, this study represents the first attempt to answer which 3D experimental system can better mimic the neoplastic architecture in vitro, emphasizing the relevance of confinement in cancer pathogenicity, which can be easily achieved by using hydrogel-based matrices.

Rac1-GTPase regulates compression-induced actin protrusions (CAPs) of mesenchymal stem cells in 3D collagen micro-tissues

Cells can sense mechanical signals through cytoskeleton reorganization. We previously discovered the formation of omni-directional actin protrusions upon compression loading, namely compression-induced actin protrusions (CAPs), in human mesenchymal stem cells (MSCs) in 3D micro-tissues. Here, the regulatory roles of three RhoGTPases (CDC42, Rac1 and RhoA) in the formation of CAPs were investigated. Upon compression loading, extensive formation of CAPs was found, significantly associated with an upregulated mRNA expression of Rac1 only, but not CDC42, nor RhoA. Upon chemical inhibition of these RhoGTPase activity during compression, only Rac1 activity was significantly suppressed, associating with the reduced CAP formation. Silencing the upstream regulators of these RhoGTPase pathways including Rac1 by specific siRNA dramatically disrupted actin cytoskeleton, distorted cell morphology and aborted CAP formation. Silencing cortactin (CTTN), a downstream effector of the Rac1 pathway, induced a compensatory upregulation of Rac1, enabling the MSCs to respond to the compression loading stimulus in terms of CAP formation, although at a reduced number. The importance of Rac1 signalling in CAP formation and the corresponding upregulation of lamellipodial markers also suggest that these CAPs are lamellipodia in nature. This study delineates the mechanism of compression-induced cytoskeleton reorganization, contributing to rationalizing mechanical loading regimes for functional tissue engineering.

Sialic acid removal by trans-sialidase modulates MMP-2 activity during Trypanosoma cruzi infection

Matrix metalloproteinases (MMPs) not only play a relevant role in homeostatic processes but are also involved in several pathological mechanisms associated with infectious diseases. As their clinical relevance in Chagas disease has recently been highlighted, we studied the modulation of circulating MMPs by Trypanosoma cruzi infection. We found that virulent parasites from Discrete Typing Units (DTU) VI induced higher proMMP-2 and MMP-2 activity in blood, whereas both low (DTU I) and high virulence parasites induced a significant decrease in proMMP-9 plasma activity. Moreover, trans-sialidase, a relevant T. cruzi virulence factor, is involved in MMP-2 activity modulation both in vivo and in vitro. It removes α2,3-linked sialyl residues from cell surface glycoconjugates, which then triggers the PKC/MEK/ERK signaling pathway. Additionally, bacterial sialidases specific for this sialyl residue linkage displayed similar MMP modulation profiles and triggered the same signaling pathways. This novel pathogenic mechanism, dependent on sialic acid removal by the neuraminidase activity of trans-sialidase, can be exploited by different pathogens expressing sialidases with similar specificity. Thus, here we present a new pathogen strategy through the regulation of the MMP network.

Sirtuin 1 and Skin: Implications in Intrinsic and Extrinsic Aging-A Systematic Review

Skin, as the outermost organ of the body, is constantly exposed to both intrinsic and extrinsic causative factors of aging. Intrinsic aging is related to compromised cellular proliferative capacity, and may be accelerated by harmful environmental influences with the greatest significance of ultraviolet radiation exposure, contributing not only to premature aging, but also to skin carcinogenesis. The overall skin cancer burden and steadily increasing global antiaging market provide an incentive for searching novel targets to improve skin resistance against external injury. Sirtuin 1, initially linked to extension of yeast and rodent lifespan, plays a key role in epigenetic modification of proteins, histones, and chromatin by which regulates the expression of genes implicated in the oxidative stress response and apoptosis. The spectrum of cellular pathways regulated by sirtuin 1 suggests its beneficial impact on skin aging. However, the data on its role in carcinogenesis remains controversial. The aim of this review was to discuss the relevance of sirtuin 1 in skin aging, in the context of intrinsic factors, related to genetic premature aging syndromes, as well as extrinsic modifiable ones, with the assessment of its future application. PubMed were searched from inception to 4 January 2021 for relevant papers with further search carried out on ClinicalTrials.gov. The systematic review included 46 eligible original articles. The evidence from numerous studies proves sirtuin 1 significance in both chronological and premature aging as well as its dual role in cancer development. Several botanical compounds hold the potential to improve skin aging symptoms.

Key Matrix Remodeling Enzymes: Functions and Targeting in Cancer

Tissue functionality and integrity demand continuous changes in distribution of major components in the extracellular matrices (ECMs) under normal conditions aiming tissue homeostasis. Major matrix degrading proteolytic enzymes are matrix metalloproteinases (MMPs), plasminogen activators, atypical proteases such as intracellular cathepsins and glycolytic enzymes including heparanase and hyaluronidases. Matrix proteases evoke epithelial-to-mesenchymal transition (EMT) and regulate ECM turnover under normal procedures as well as cancer cell phenotype, motility, invasion, autophagy, angiogenesis and exosome formation through vital signaling cascades. ECM remodeling is also achieved by glycolytic enzymes that are essential for cancer cell survival, proliferation and tumor progression. In this article, the types of major matrix remodeling enzymes, their effects in cancer initiation, propagation and progression as well as their pharmacological targeting and ongoing clinical trials are presented and critically discussed.

The Burden of Post-Translational Modification (PTM)-Disrupting Mutations in the Tumor Matrisome

BACKGROUND

To evaluate the occurrence of mutations affecting post-translational modification (PTM) sites in matrisome genes across different tumor types, in light of their genomic and functional contexts and in comparison with the rest of the genome.

METHODS

This study spans 9075 tumor samples and 32 tumor types from The Cancer Genome Atlas (TCGA) Pan-Cancer cohort and identifies 151,088 non-silent mutations in the coding regions of the matrisome, of which 1811 affecting known sites of hydroxylation, phosphorylation, N- and O-glycosylation, acetylation, ubiquitylation, sumoylation and methylation PTM.

RESULTS

PTM-disruptive mutations (PTMmut) in the matrisome are less frequent than in the rest of the genome, seem independent of cell-of-origin patterns but show dependence on the nature of the matrisome protein affected and the background PTM types it generally harbors. Also, matrisome PTMmut are often found among structural and functional protein regions and in proteins involved in homo- and heterotypic interactions, suggesting potential disruption of matrisome functions.

CONCLUSIONS

Though quantitatively minoritarian in the spectrum of matrisome mutations, PTMmut show distinctive features and damaging potential which might concur to deregulated structural, functional, and signaling networks in the tumor microenvironment.

A guide to the composition and functions of the extracellular matrix

Extracellular matrix (ECM) is a dynamic 3-dimensional network of macromolecules that provides structural support for the cells and tissues. Accumulated knowledge clearly demonstrated over the last decade that ECM plays key regulatory roles since it orchestrates cell signaling, functions, properties and morphology. Extracellularly secreted as well as cell-bound factors are among the major members of the ECM family. Proteins/glycoproteins, such as collagens, elastin, laminins and tenascins, proteoglycans and glycosaminoglycans, hyaluronan, and their cell receptors such as CD44 and integrins, responsible for cell adhesion, comprise a well-organized functional network with significant roles in health and disease. On the other hand, enzymes such as matrix metalloproteinases and specific glycosidases including heparanase and hyaluronidases contribute to matrix remodeling and affect human health. Several cell processes and functions, among them cell proliferation and survival, migration, differentiation, autophagy, angiogenesis, and immunity regulation are affected by certain matrix components. Structural alterations have been also well associated with disease progression. This guide on the composition and functions of the ECM gives a broad overview of the matrisome, the major ECM macromolecules, and their interaction networks within the ECM and with the cell surface, summarizes their main structural features and their roles in tissue organization and cell functions, and emphasizes the importance of specific ECM constituents in disease development and progression as well as the advances in molecular targeting of ECM to design new therapeutic strategies.

Cathepsins in neuronal plasticity

Proteases comprise a variety of enzymes defined by their ability to catalytically hydrolyze the peptide bonds of other proteins, resulting in protein lysis. Cathepsins, specifically, encompass a class of at least twenty proteases with potent endopeptidase activity. They are located subcellularly in lysosomes, organelles responsible for the cell’s degradative and autophagic processes, and are vital for normal lysosomal function. Although cathepsins are involved in a multitude of cell signaling activities, this chapter will focus on the role of cathepsins (with a special emphasis on Cathepsin B) in neuronal plasticity. We will broadly define what is known about regulation of cathepsins in the central nervous system and compare this with their dysregulation after injury or disease. Importantly, we will delineate what is currently known about the role of cathepsins in axon regeneration and plasticity after spinal cord injury. It is well established that normal cathepsin activity is integral to the function of lysosomes. Without normal lysosomal function, autophagy and other homeostatic cellular processes become dysregulated resulting in axon dystrophy. Furthermore, controlled activation of cathepsins at specialized neuronal structures such as axonal growth cones and dendritic spines have been positively implicated in their plasticity. This chapter will end with a perspective on the consequences of cathepsin dysregulation versus controlled, localized regulation to clarify how cathepsins can contribute to both neuronal plasticity and neurodegeneration.

Pharmacological Inhibition of MMP3 as a Potential Therapeutic Option for COVID-19 Associated Acute Respiratory Distress Syndrome

The high mortality of coronavirus disease 2019 (COVID-19) patients is due to their progression to cytokine-associated organ injuries, primarily the acute respiratory distress syndrome (ARDS). The uncertainties in the molecular mechanisms leading to the switch from the early virus infection to the advanced stage ARDS is a major gridlock in therapeutic development to reduce mortality. Previous studies in our laboratory have identified matrix metalloprotease-3 (MMP3) as an important mediator of bacterial lipopolysaccharide (LPS)-induced ARDS, particularly in the exudative phase. Our studies have also reported elevated plasma MMP3 activity levels in the ARDS patients and that inhibition of MMP3 can reduce the severity of LPS-induced ARDS in mice. Given these observations, targeting MMP3 could be a potential option to treat COVID-19 patients with ARDS, and measurement of MMP3 activity in the plasma may serve as a biomarker for the early detection of ARDS in COVID-19 patients.

Unravelling the Network of Nuclear Matrix Metalloproteinases for Targeted Drug Design

Matrix metalloproteinases (MMPs) are zinc-dependent endopeptidases that are responsible for the degradation of a wide range of extracellular matrix proteins, which are involved in many cellular processes to ensure the normal development of tissues and organs. Overexpression of MMPs has been observed to facilitate cellular growth, migration, and metastasis of tumor cells during cancer progression. A growing number of these proteins are being found to exist in the nuclei of both healthy and tumor cells, thus highlighting their localization as having a genuine purpose in cellular homeostasis. The mechanism underlying nuclear transport and the effects of MMP nuclear translocation have not yet been fully elucidated. To date, nuclear MMPs appear to have a unique impact on cellular apoptosis and gene regulation, which can have effects on immune response and tumor progression, and thus present themselves as potential therapeutic targets in certain types of cancer or disease. Herein, we highlight and evaluate what progress has been made in this area of research, which clearly has some value as a specific and unique way of targeting the activity of nuclear matrix metalloproteinases within various cell types.

Citrullination as a novel posttranslational modification of matrix metalloproteinases

Matrix metalloproteinases (MMPs) are enzymes with critical roles in biology and pathology. Glycosylation, nitrosylation and proteolysis are known posttranslational modifications (PTMs) regulating intrinsically the activities of MMPs. We discovered MMP citrullination by peptidyl arginine deiminases (PADs) as a new PTM. Upon hypercitrullination, MMP-9 acquired a higher affinity for gelatin than control MMP-9. Furthermore, hypercitrullinated proMMP-9 was more efficiently activated by MMP-3 compared to control MMP-9. JNJ0966, a specific therapeutic inhibitor of MMP-9 activation, inhibited the activation of hypercitrullinated proMMP-9 by MMP-3 significantly less in comparison with control proMMP-9. The presence of citrullinated/homocitrullinated MMP-9 was detected in vivo in neutrophil-rich sputum samples of cystic fibrosis patients. In addition to citrullination of MMP-9, we report efficient citrullination of MMP-1 and lower citrullination levels of MMP-3 and MMP-13 by PAD2 in vitro. In conclusion, citrullination of MMPs is a new PTM worthy of additional biochemical and biological studies.

Focusing Heart Failure Research on Myocardial Fibrosis to Prioritize Translation

Heart failure (HF) has traditionally been defined by symptoms of fluid accumulation and poor perfusion, but it is now recognized that specific HF classifications hold prognostic and therapeutic relevance. Specifically, HF with reduced ejection fraction is characterized by reduced left ventricular systolic pump function and dilation and HF with preserved ejection fraction is characterized primarily by abnormal left ventricular filling (diastolic failure) with relatively preserved left ventricular systolic function. These forms of HF are distributed equally among patients with HF and likely require distinctly different strategies to mitigate the morbidity, mortality, and medical resource utilization of this disease. In particular, HF is a significant medical issue within the US Department of Veterans Affairs (VA) hospital system and constitutes a major translational research priority for the VA. Because a common underpinning of both HF with reduced ejection fraction and HF with preserved ejection fraction seems to be changes in the structure and function of the myocardial extracellular matrix, a conference was convened sponsored by the VA, entitled, "Targeting Myocardial Fibrosis in Heart Failure" to explore the extracellular matrix as a potential therapeutic target and to propose specific research directions. The conference was conceptually framed around the hypothesis that although HF with reduced ejection fraction and HF with preserved ejection fraction clearly have distinct mechanisms, they may share modifiable pathways and biological mediators in common. Inflammation and extracellular matrix were identified as major converging themes. A summary of our discussion on unmet challenges and possible solutions to move the field forward, as well as recommendations for future research opportunities, are provided.

Structural and functional diversity of neutrophil glycosylation in innate immunity and related disorders

The granulated neutrophils are abundant innate immune cells that utilize bioactive glycoproteins packed in cytosolic granules to fight pathogenic infections, but the neutrophil glycobiology remains poorly understood. Facilitated by technological advances in glycoimmunology, systems glycobiology and glycoanalytics, a considerable body of literature reporting on novel aspects of neutrophil glycosylation has accumulated. Herein, we summarize the building knowledge of the structural and functional diversity displayed by N- and O-linked glycoproteins spatiotemporally expressed and sequentially brought-into-action across the diverse neutrophil life stages during bone marrow maturation, movements to, from and within the blood circulation and microbicidal processes at the inflammatory sites in peripheral tissues. It transpires that neutrophils abundantly decorate their granule glycoproteins including neutrophil elastase, myeloperoxidase and cathepsin G with peculiar glyco-signatures not commonly reported in other areas of human glycobiology such as hyper-truncated chitobiose core- and paucimannosidic-type N-glycans and monoantennary complex-type N-glycans. Sialyl Lewis^x, Lewis^x, poly-N-acetyllactosamine extensions and core 1-/2-type O-glycans are also common neutrophil glyco-signatures. Granule-specific glycosylation is another fascinating yet not fully understood feature of neutrophils. Recent literature suggests that unconventional biosynthetic pathways and functions underpin these prominent neutrophil-associated glyco-phenotypes. The impact of glycosylation on key neutrophil effector functions including extravasation, degranulation, phagocytosis and formation of neutrophil extracellular traps during normal physiological conditions and in innate immune-related diseases is discussed. We also highlight new technologies that are expected to further advance neutrophil glycobiology and briefly discuss the untapped diagnostic and therapeutic potential of neutrophil glycosylation that could open avenues to combat the increasingly prevalent innate immune disorders.