A Novel Function for Lysyl Oxidase in Pluripotent Mesenchymal Cell Proliferation and Relevance to Inflammation-Associated Osteopenia

Abstract

Lysyl oxidase is a multifunctional enzyme required for collagen biosynthesis. Various growth factors regulate lysyl oxidase during osteoblast differentiation, subject to modulation by cytokines such as TNF-α in inflammatory osteopenic disorders including diabetic bone disease. Canonical Wnt signaling promotes osteoblast development. Here we investigated the effect of Wnt3a and TNF-α on lysyl oxidase expression in pluripotent C3H10T1/2 cells, bone marrow stromal cells, and committed osteoblasts. Lysyl oxidase was up-regulated by a transcriptional mechanism 3-fold in C3H10T1/2 cells, and 2.5-fold in bone marrow stromal cells. A putative functional TCF/LEF element was identified in the lysyl oxidase promoter. Interestingly, lysyl oxidase was not up-regulated in committed primary rat calvarial- or MC3T3-E1 osteoblasts. TNF-α down-regulated lysyl oxidase both in Wnt3a-treated and in non-treated C3H10T1/2 cells by a post-transcriptional mechanism mediated by miR203. Non-differentiated cells do not produce a collagen matrix; thus, a novel biological role for lysyl oxidase in pluripotent cells was investigated. Lysyl oxidase shRNAs effectively silenced lysyl oxidase expression, and suppressed the growth of C3H10T1/2 cells by 50%, and blocked osteoblast differentiation. We propose that interference with lysyl oxidase expression under excess inflammatory conditions such as those that occur in diabetes, osteoporosis, or rheumatoid arthritis can result in a diminished pool of pluripotent cells which ultimately contributes to osteopenia.

Stem Cells Antigen-1 Enriches for a Cancer Stem Cell-Like Subpopulation in Mouse Gastric Cancer

“…We compared mRNA expression array profiles between Sca‐1‐high S1 cells and Sca‐1‐negative S1 cells and identified 85 genes overexpressed by > 1.5‐fold in S1M cells ( Sca‐1 signature ) (Supporting Information Table S3). The Sca‐1 signature included a Wnt ligand, wnt7a, and Wnt positive regulators, such as Nestin , PRRX1 , and TNC , and putative Wnt target genes, such as LOX , Ifitm3 , and Lipocalin2 . Thus, the microarray data indicated the transcriptional activation of the Wnt signaling pathway in Sca‐1 high cells.…”

Nano-copper-bearing stainless steel promotes fracture healing by accelerating the callus evolution process

“…45 The crosslinking then facilitates callus osteogenesis and provides the necessary framework for bone mineralization. 46 In this work, we proved through the in vitro experiment that 317L-Cu SS has significant effect in enhancing the activity of LOX in hBMSCs. It is possibly because of this that more of the woven fibrous tissue was observed through Masson staining in the early stage of callus formation in the 317L-Cu SS group.…”

Enzymatic and non-enzymatic functions of the lysyl oxidase family in bone

“…Because C3H10T1/2 cells produce little or no extracellular matrix under these conditions, the question was raised regarding LOX function. LOX shRNA studies showed that LOX was required for normal proliferation of C3H10T1/2 cells, and that differentiation into osteoblasts was blocked in cells expressing diminished levels of LOX [74]. Similarly, LOX expression was found to be required for differentiation of C3H10T1/2 cells to adipocytes [75, 76].…”

“…Decreased OPG and increased CCN2 can each contribute to osteoclast development and fusion [94, 95] which was observed to be increased in the presence of rLOX-PP [92]. The relative contributions and mechanisms of abnormal high levels of active LOX enzyme on the one hand [60, 74, 93], and LOX-PP on the other, to decouple osteoblast and osteoclast interactions in the presence or absence of cancer cells [92] remain to be adequately understood, and are likely to influence bone metastasis. For example, direct injection of the osteolytic prostate cancer PC3 cell line over expressing rLOX-PP into the tibia of mice increased bone destruction compared to PC3 control cells determined by μCT analyses, while injection of DU145 osteogenic cancer cells overexpressing rLOX-PP created osteoblastic lesions that were similar compared to its DU145 control [92].…”