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An in situ activity assay for lysyl oxidases.

ABSTRACT: The lysyl oxidase family of enzymes (LOXs) catalyze oxidative deamination of lysine side chains on collagen and elastin to initialize cross-linking that is essential for the formation of the extracellular matrix (ECM). Elevated expression of LOXs is highly associated with diverse disease processes. To date, the inability to detect total LOX catalytic function in situ has limited the ability to fully elucidate the role of LOXs in pathobiological mechanisms. Using LOXL2 as a representative member of the LOX family, we developed an in situ activity assay by utilizing the strong reaction between hydrazide and aldehyde to label the LOX-catalyzed allysine (-CHO) residues with biotin-hydrazide. The biotinylated ECM proteins are then labeled via biotin-streptavidin interaction and detected by fluorescence microscopy. This assay detects the total LOX activity in situ for both overexpressed and endogenous LOXs in cells and tissue samples and can be used for studies of LOXs as therapeutic targets.

SUBMITTER: Wang H

PROVIDER: S-EPMC8257687 | biostudies-literature | 2021 Jul

REPOSITORIES: biostudies-literature

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An in situ activity assay for lysyl oxidases.

Wang Huilei H Poe Alan A Pak Lydia L Nandakumar Kavitha K Jandu Sandeep S Steppan Jochen J Löser Reik R Santhanam Lakshmi L

Communications biology 20210705 1

The lysyl oxidase family of enzymes (LOXs) catalyze oxidative deamination of lysine side chains on collagen and elastin to initialize cross-linking that is essential for the formation of the extracellular matrix (ECM). Elevated expression of LOXs is highly associated with diverse disease processes. To date, the inability to detect total LOX catalytic function in situ has limited the ability to fully elucidate the role of LOXs in pathobiological mechanisms. Using LOXL2 as a representative member ...[more]

PMID: 34226627

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Origin and evolution of lysyl oxidases.

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Fibrosis in Mesothelioma: Potential Role of Lysyl Oxidases.

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VE-statin/egfl7 regulates vascular elastogenesis by interacting with lysyl oxidases.

Project description:We previously characterized VE-statin/egfl7, a protein that is exclusively secreted by endothelial cells and modulates smooth muscle cell migration. Here, we show that VE-statin/egfl7 is the first known natural negative regulator of vascular elastogenesis. Transgenic mice, expressing VE-statin/egfl7 under the control of keratin-14 promoter, showed an accumulation of VE-statin/egfl7 in arterial walls where its presence correlated with an impaired organization of elastic fibres. In vitro, fibroblasts cultured in the presence of VE-statin/egfl7 were unable to deposit elastic fibres due to a deficient conversion of soluble tropoelastin into insoluble mature elastin. VE-statin/egfl7 interacts with the catalytic domain of lysyl oxidase (LOX) enzymes and, in endothelial cells, endogenous VE-statin/egfl7 colocalizes with LoxL2 and inhibits elastic fibre deposition. In contrast, mature elastic fibres are abundantly deposited by endothelial cells that are prevented from producing endogenous VE-statin/egfl7. We propose a model where VE-statin/egfl7 produced by endothelial cells binds to the catalytic domains of enzymes of the LOX family in the vascular wall, thereby preventing the crosslink of tropoelastin molecules into mature elastin polymers and regulating vascular elastogenesis.

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The Expression Patterns and Roles of Lysyl Oxidases in Aortic Dissection.

Project description:Background: Lysyl oxidases (LOXs), including LOX, LOXL1, LOXL2, LOXL3, and LOXL4, catalyze the formation of a cross-link between elastin (ELN) and collagen. Multiple LOX mutations have been shown to be associated with the occurrence of aortic dissection (AD) in humans, and LOX-knockout mice died during the perinatal period due to aortic aneurysm and rupture. However, the expression levels and roles of other LOX members in AD remain unknown. Methods: A total of 33 aorta samples of AD and 15 normal aorta were collected for LOXs mRNA and protein levels detection. We also analyzed the datasets of AD in GEO database through bioinformatics methods. LOXL2 and LOXL3 were knocked down in primary cultured human aortic smooth muscle cells (HASMCs) via lentivirus. Results: Here, we show that the protein levels of LOXL2 and LOXL3 are upregulated, while LOXL4 is downregulated in AD subjects compared with non-AD subjects, but comparable protein levels of LOX and LOXL1 are detected. Knockdown of LOXL2 suppressed MMP2 expression, the phosphorylation of AKT (p-AKT) and S6 (p-S6), but increased the mono-, di-, tri-methylation of H3K4 (H3K4me1/2/3), H3K9me3, and p-P38 levels in HASMCs. These results indicate that LOXL2 is involved in regulation of the extracellular matrix (ECM) in HASMCs. In contrast, LOXL3 knockdown inhibited PCNA and cyclin D1, suppressing HASMC proliferation. Our results suggest that in addition to LOX, LOXL2 and LOXL3 are involved in the pathological process of AD by regulating ECM and the proliferation of HASMCs, respectively. Furthermore, we found that LOXL2 and LOXL4 was inhibited by metformin and losartan in HASMCs, which indicated that LOXL2 and LOXL4 are the potential targets that involved in the therapeutic effects of metformin and losartan on aortic or aneurysm expansion. Conclusions: Thus, differential regulation of LOXs might be a novel strategy to prevent or treat AD.

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A scalable lysyl hydroxylase 2 expression system and luciferase-based enzymatic activity assay.

Project description:Hydroxylysine aldehyde-derived collagen cross-links (HLCCs) accumulate in fibrotic tissues and certain types of cancer and are thought to drive the progression of these diseases. HLCC formation is initiated by lysyl hydroxylase 2 (LH2), an Fe(II) and α-ketoglutarate (αKG)-dependent oxygenase that hydroxylates telopeptidyl lysine residues on collagen. Development of LH2 antagonists for the treatment of these diseases will require a reliable source of recombinant LH2 protein and a non-radioactive LH2 enzymatic activity assay that is amenable to high throughput screens of small molecule libraries. However, LH2 protein generated using E coli- or insect-based expression systems is either insoluble or enzymatically unstable, and the LH2 enzymatic activity assays that are currently available measure radioactive CO2 released from 14C-labeled αKG during its conversion to succinate. To address these deficiencies, we have developed a scalable process to purify human LH2 protein from Chinese hamster ovary cell-derived conditioned media samples and a luciferase-based assay that quantifies LH2-dependent conversion of αKG to succinate. These methodologies may be applicable to other Fe(II) and αKG-dependent oxygenase systems.

| S-EPMC5619865 | biostudies-literature

Inhibition of Lysyl Oxidases Impairs Migration and Angiogenic Properties of Tumor-Associated Pericytes.

Project description:Pericytes are important cellular components of the tumor microenviroment with established roles in angiogenesis and metastasis. These two cancer hallmarks are modulated by enzymes of the LOX family, but thus far, information about LOX relevance in tumor-associated pericytes is lacking. Here, we performed a comparative characterization of normal and tumoral pericytes and report for the first time the modulatory effects of LOX enzymes on activated pericyte properties. Tumoral pericytes isolated from childhood ependymoma and neuroblastoma specimens displayed angiogenic properties in vitro and expressed typical markers, including CD146, NG2, and PDGFRβ. Expression of all LOX family members could be detected in both normal and tumor-associated pericytes. In most pericyte samples, LOXL3 was the family member displaying the highest transcript levels. Inhibition of LOX/LOXL activity with the inhibitor β-aminopropionitrile (βAPN) significantly reduced migration of pericytes, while proliferation rates were kept unaltered. Formation of tube-like structures in vitro by pericytes was also significantly impaired upon inhibition of LOX/LOXL activity with βAPN, which induced more prominent effects in tumor-associated pericytes. These findings reveal a novel involvement of the LOX family of enzymes in migration and angiogenic properties of pericytes, with implications in tumor development and in therapeutic targeting tumor microenvironment constituents.

| S-EPMC5434472 | biostudies-literature

Topical application of an irreversible small molecule inhibitor of Lysyl Oxidases ameliorates skin scarring and fibrosis

Project description:Next-generation sequencing (NGS) has been performed to investigate the effect of Lysyl oxidase inhibition by PXS-4787A on transcriptome of normal skin derived fibroblasts and keratinocytes. Fibroblasts and keratinocytes of low passage (p2-5) were cultured onto T25 flasks until ~70% confluence was reached. Fibroblasts were treated with or without 10 µM PXS-4787A in complete fibroblast growth media for 48 hours at 37°C. Keratinocytes were treated with 10 µM PXS-4787A with basal keratinocyte medium supplemented with 1.2 mM calcium chloride for 48 hours at 37°C. Cells were then collected using 0.05% trypsin and washed in Phosphate Buffered Saline (PBS). RNA was extracted using the RNeasy Mini kit protocol. Samples were then sent to the Australian Genome Research Facility (AGRF) where 1μg of RNA was submitted for next-generation sequencing. Once raw data returned, bioinformatics analyses were conducted. This study found that the exposure of PXS-4787A only had minor impact on gene expression in both fibroblasts and keratinocytes. In fibroblasts, 3 genes were significantly upregulated and only one gene was significantly downregulated. Besides, There were only two upregulated genes in the whole genome analysis after LOX inhibition in keratinocytes. In conclusion, this study highlights the safety of LOX-inhibition through PXS-4787A on primary human epidermal cells. The results of the transcriptome analysis intimate that PXS-4787A treatment has no adverse effects on the healthy keratinocytes. Taken together, this study suggests that LOX-inhibition has no potential effects on the epidermal differentiation in human skin.

2020-12-17 | GSE163309 | GEO

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