Project description:The members of the lysyl oxidase (LOX) family are amine oxidases, which initiate the covalent cross-linking of the extracellular matrix (ECM), regulate ECM stiffness, and contribute to cancer progression. The aim of this study was to build the first draft of the interactome of the five members of the LOX family in order to determine its molecular functions, the biological and signaling pathways mediating these functions, the biological processes it is involved in, and if and how it is rewired in cancer. In vitro binding assays, based on surface plasmon resonance and bio-layer interferometry, combined with queries of interaction databases and interaction datasets, were used to retrieve interaction data. The interactome was then analyzed using computational tools. We identified 31 new interactions and 14 new partners of LOXL2, including the α5β1 integrin, and built an interactome comprising 320 proteins, 5 glycosaminoglycans, and 399 interactions. This network participates in ECM organization, degradation and cross-linking, cell-ECM interactions mediated by non-integrin and integrin receptors, protein folding and chaperone activity, organ and blood vessel development, cellular response to stress, and signal transduction. We showed that this network is rewired in colorectal carcinoma, leading to a switch from ECM organization to protein folding and chaperone activity.
Project description:Mutations in lysyl oxidase (LOX) are associated with thoracic aortic aneurysm and dissection (TAAD). Mice that do not express Lox (Lox-/- ) die soon after birth and have 60% and 40% reductions in elastin- and collagen-specific cross-links, respectively. LOX inactivation could also change the expression of secreted factors, the structural matrix, and matrix-associated proteins that constitute the aortic matrisome. We hypothesized that absence of Lox will change the mechanical behavior of the aortic wall because of reduced elastin and collagen cross-linking and alter the expression levels of matrisome and smooth muscle cell (SMC) genes in a vascular location-specific manner. Using fluorescence microscopy, pressure myography, and gene set enrichment analysis, we visualized the microarchitecture, quantified the mechanical behavior, and examined matrisome and SMC gene expression from ascending aortas (AAs) and descending aortas (DAs) from newborn Lox+/+ and Lox-/- mice. Even though Lox-/- AAs and DAs have fragmented elastic laminae and disorganized SMCs, the unloaded outer diameter and wall thickness were similar to Lox+/+ AAs and DAs. Lox-/- AAs and DAs have altered opening angles, circumferential stresses, and circumferential stretch ratios; however, only Lox-/- AAs have increased pressurized diameters and tangent moduli. Gene set enrichment analysis showed upregulation of the extracellular matrix (ECM) regulator gene set in Lox-/- AAs and DAs as well as differential expression of secreted factors, collagens, ECM-affiliated proteins, ECM glycoproteins, and SMC cell cycle gene sets that depend on the Lox genotype and vascular location. These results provide insights into the local chemomechanical changes induced by Lox inactivation that may be important for TAAD pathogenesis.NEW & NOTEWORTHY Absence of lysyl oxidase (Lox) causes thoracic aortic aneurysms. The aortic mechanical behavior of Lox-/- mice is consistent with reduced elastin and collagen cross-linking but demonstrates vascular location-specific differences. Lox-/- aortas show upregulation of matrix remodeling genes and location-specific differential expression of other matrix and smooth muscle cell gene sets.
Project description:Lysyl oxidase of bovine aorta was resolved into four enzymically active species by elution from DEAE-cellulose with a salt gradient in 6m-urea, consistent with purification results obtained with enzyme of other tissues [Stassen (1976) Biochim. Biophys. Acta438, 49-60]. In the present study, each of the four peaks of activity was purified to apparent homogeneity by subsequent chromatography on gel-filtration media in 6m-urea. Each enzyme is eluted as a species with mol.wt. approx. 30000 under these conditions, although lysyl oxidase polymerizes to a series of multimers with molecular weights ranging up to 1000000 in the absence of urea. The apparent subunit molecular weight of each enzyme species determined by electrophoresis in sodium dodecyl sulphate and 8m-urea is approx. 32000-33000. The amino acid compositions of the purified forms of lysyl oxidase are similar to each other, although sufficient differences exist to conclude that each is a unique molecular species. Incorporation of alpha-toluenesulphonyl fluoride into the purification scheme does not alter the resolution of enzyme into four species, suggesting that proteolysis during isolation is not the basis of the heterogeneity. The similar sensitivities of each form of enzyme to chelating agents and to semicarbazide and isoniazid indicate that each requires the participation of a metal ion, presumably Cu(2+), and of a carbonyl compound for enzyme function. The present study describes a method for the purification of multiple species of lysyl oxidase and reveals that significant chemical differences exist between the different enzyme forms.
Project description:Surgery remains the most successful curative treatment for cancer. However, some patients with early-stage disease who undergo surgery eventually succumb to distant metastasis. Here, we show that in response to surgery, the lungs become more vulnerable to metastasis due to extracellular matrix remodeling. Mice that undergo surgery or that are preconditioned with plasma from donor mice that underwent surgery succumb to lung metastases earlier than controls. Increased lysyl oxidase (LOX) activity and expression, fibrillary collagen crosslinking, and focal adhesion signaling contribute to this effect, with the hypoxic surgical site serving as the source of LOX. Furthermore, the lungs of recipient mice injected with plasma from post-surgical colorectal cancer patients are more prone to metastatic seeding than mice injected with baseline plasma. Downregulation of LOX activity or levels reduces lung metastasis after surgery and increases survival, highlighting the potential of LOX inhibition in reducing the risk of metastasis following surgery.
Project description:LKB1 loss-of-function mutations, observed in ∼30% of human lung adenocarcinomas, contribute significantly to lung cancer malignancy progression. We show that lysyl oxidase (LOX), negatively regulated by LKB1 through mTOR-HIF-1α signaling axis, mediates lung cancer progression. Inhibition of LOX activity dramatically alleviates lung cancer malignancy progression. Up-regulated LOX expression triggers excess collagen deposition in Lkb1-deficient lung tumors, and thereafter results in enhanced cancer cell proliferation and invasiveness through activation of β1 integrin signaling. High LOX level and activity correlate with poor prognosis and metastasis. Our findings provide evidence of how LKB1 loss of function promotes lung cancer malignancy through remodeling of extracellular matrix microenvironment, and identify LOX as a potential target for disease treatment in lung cancer patients.
Project description:Lysyl oxidase like-2 (LOXL2) belongs to the lysyl oxidase (LOX) family, which comprises Cu(2+)- and lysine tyrosylquinone (LTQ)-dependent amine oxidases. LOXL2 is proposed to function similarly to LOX in the extracellular matrix (ECM) by promoting crosslinking of collagen and elastin. LOXL2 has also been proposed to regulate extracellular and intracellular cell signaling pathways. Dysregulation of LOXL2 has been linked to many diseases, including cancer, pro-oncogenic angiogenesis, fibrosis and heart diseases. In this review, we will give an overview of the current understandings and hypotheses regarding the molecular functions of LOXL2.
Project description:BackgroundEhlers-Danlos syndrome Type IV (aka Vascular Ehlers Danlos, or vEDS) is a dominantly inherited mutation in the Collagen 3A1 gene (COL3A1). The disease is characterized by tissue friability and age-related susceptibility to arterial aneurysm, dissection and rupture as well as uterine and bowl tears. These clinical manifestations result in major surgical intervention and decreased life expectancy. Understanding how mutations in COL3A1 impact the structure and function of the extracellular matrix (ECM) is important to managing the disease and finding treatments.ResultsSkin fibroblasts from vEDS subjects heterozygous for the p.G588S pathogenic variant in the COL3A1 gene and a normal individual were cultured and studied. Proteomics analysis identified dozens of upregulated proteins related to extracellular matrix dysregulation that is characteristic of fibrosis. Gene expression libraries from cultured primary fibroblasts were screened for messenger RNA (mRNA) markers of ECM degradation. The proteomics and targeted gene expression array results were largely consistent with dysregulation of the extracellular matrix in vEDS. The data show upregulation of multiple Collagen proteins and genes, other ECM components, and enzymes related to ECM processing and turn-over. vEDS fibroblasts expressed significantly more cross linked C-Telopeptide of Collagen III (CTXIII) than normal fibroblasts, indicative of Collagen III degradation and turn-over. Further, the expression and activity of Lysyl Oxidase (LOX), an enzyme that initiates covalent cross-linking of soluble collagen and elastin into protease resistant fibers, is elevated in vEDS fibroblasts compared to normal fibroblasts.ConclusionTogether, these findings suggest dysregulated ECM deposition and processing, reminiscent of a state of fibrosis. Therapeutics that target the dysregulated ECM proteins or help replace damaged tissue may improve clinical outcomes.
Project description:Tumor cell metastasis is facilitated by "premetastatic niches" formed in destination organs by invading bone marrow-derived cells (BMDCs). Lysyl oxidase (LOX) is critical for premetastatic niche formation. LOX secreted by hypoxic breast tumor cells accumulates at premetastatic sites, crosslinks collagen IV in the basement membrane, and is essential for CD11b+ myeloid cell recruitment. CD11b+ cells adhere to crosslinked collagen IV and produce matrix metalloproteinase-2, which cleaves collagen, enhancing the invasion and recruitment of BMDCs and metastasizing tumor cells. LOX inhibition prevents CD11b+ cell recruitment and metastatic growth. CD11b+ cells and LOX also colocalize in biopsies of human metastases. Our findings demonstrate a critical role for LOX in premetastatic niche formation and support targeting LOX for the treatment and prevention of metastatic disease.